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Über dieses Buch

This book highlights current research and development in the area of sustainable built environments, currently one of the most important disciplines in civil engineering. It covers a range of topics, including sustainable construction and infrastructures, waste and wastewater management, enhanced sustainability, renewable and clean energy, sustainable materials and industrial ecology, building automation and virtual reality, and impact of climate change. As such it provides vital insights into responsible urbanization practices, and new tools and technologies in civil engineering that can mitigate the negative effects of the built environment.



Climate Change and Sustainable Transportation


Important Aspects of Evacuation Planning for the Coastal Communities in Sri Lanka

Sri Lanka is a tropical island in the Indian Ocean which has suffered from various disasters in the recent past. Flood events which occurred in the last three consecutive years clearly shows that the country is affected from climate change. During a disaster event, evacuation of vulnerable and affected communities is necessary to reduce the number of deaths. In the Sri Lankan perspective, most of the recent disasters severely damaged the coastal belt of the country. This study was carried out to evaluate the different aspects of evacuation planning with respect to the coastal districts in Sri Lanka. Some of the aspects considered are early warning dissemination, evacuation routes, shelters, drills and training and the effects of having a family vehicle, disabled people, neighbours and domestic animals. During this study, an online questionnaire survey was distributed after carrying out an in-depth literature survey to gather data. The lack of trust in authorities who disseminate early warnings and limited knowledge on evacuation routes and shelters in the residential areas are some of the key issues which were identified during this study. Furthermore, it was identified that social media plays a pivotal role in disseminating the early warnings in the urban areas. Increasing the number of awareness campaigns related to evacuation and using social media wisely are some of the recommendations made, which will build the coastal community resilience via proactive measures.

G. P. Jayasiri, O. P. C. Randil, G. M. C. A. Perera, C. S. A. Siriwardana, P. B. R. Dissanayake, C. S. Bandara

Application of GPS/GIS Based Travel Mode Detection Method for Energy Efficient Transportation Sector

The planning of efficient transportation systems is a central topic of concern as it saves energy and contributes to economic development both at national and household level. The development and optimization of highway and transportation engineering models such as transportation networks, parking facilities and as well as reduction of traffic congestion etc., require information on travel modes. To overcome the burdens for the respondent and the other drawbacks of the conventional methods related to travel mode detection, combination of Global Positioning System (GPS) and Geographical Information System (GIS) were tested in this research. After validating the accuracy of the smartphone based ‘My Tracks’ GPS mobile application, GPS travel route with a manually entered travel mode diary was used to collect data from randomly selected days and students in two faculties in the University of Peradeniya. Out of 125 datasets, 99 accurate datasets were selected for the analysis using ‘ArcGIS’ software coupling with ‘STATA’ statistical software. Rule-Based algorithms and heuristic based methods are two main approaches that were used to detect four travel modes (Walk, Bus, Motor Vehicles and Motor Bicycles). Differentiation of Bus mode from the motor vehicles (except motor bicycles) was the most challenging part of the research and a country specific novel method was introduced in this research. Travel mode detection results were compared with relevant correctly completed travel mode diaries to validate the methodology. The overall travel mode detection accuracy of the new method is 96% for the accurate data sets compared to conventional travel mode diary method. The success rate of collecting an accurate data set is 79%. The GPS/GIS based travel mode detection could be applied in energy efficient development in the transportation sector. In future research, the bus mode detection method invented in this research could be used to detect driver behaviour.

G. W. H. A. Chandrasiri, K. A. G. G. K. Kumarasinghe, H. K. Nandalal

Selection of Optimum Junction Operation Strategy for Gatambe Intersection Using VISSIM Simulation

At present, traffic congestion is a major issue in the Kandy city area. It is observed that most of the congestion occurs at junctions and intersections. One of the most congested locations in the Kandy road network is the Gatambe junction. Under this research, the aim is to simulate the Peradeniya – Gatambe corridor using VISSIM simulation software and identify the optimum junction improvement strategy for the Gatambe intersection. Gatambe intersection is a four-way intersection that connects the Colombo – Kandy road (A1), William Gopallawa Mw (AB42) and Gannoruwa road (B365) directly. At present, the Gatambe intersection operates as a roundabout and at peak hours it is controlled manually by traffic police. Because of the heavy upstream traffic congestion near the Gatambe intersection, queues propagate upstream of the junction. Although many solutions including those needing heavy capital investment have been proposed to reduce congestion at Getambe junction, it is important that all possible solutions are tested on a simulation model before any physical implementation. In this study VISSIM is used as the simulation model. VISSIM is a microscopic simulation model that can predict network performance at the operational level, optimize control systems, and predict their behaviour before implementation. For simulation the necessary geometric and traffic data were collected as the first step. Then, the existing situation was simulated using VISSIM and the results validated with the observed survey queue length results. After that, the model was used to simulate three improvement strategies; signalization without geometric improvement, signalization with geometric improvement and grade separation. According to the delay results, the benefit of each alternative was estimated and a cost benefit analysis was conducted to identify optimum junction improvement strategy.

K. L. D. Maduranga, R. G. N. Yasamali, I. M. S. Sathyaprasad, H. U. Weerakoon

Gap Assessment of Warning and Dissemination Process of Early Warning System in Coastal Areas of Sri Lanka

Multi Hazard Early Warning Systems (MHEWS) issue warnings to help communities safely evacuate from hazardous areas. Studies showed that the response of coastal communities to warnings issued by the existing MHEW system in Asian countries including Sri Lanka is insufficient. In this study, the current context and gaps of MHEW system related to the “warning and dissemination” process in the coastal regions of Sri Lanka were identified using a proper research methodology. Survey was carried out through oral questionnaires in selected coastal areas of Sri Lanka. By interpreting the output of the interviews, along with a deep literature review, the current context and gaps of the MHEW systems related to warning and dissemination in coastal areas of Sri Lanka were listed out. From the identified problems, key areas which need special attention of the Disaster Management Centre, were highlighted. Among them, introducing a better Nation-wide Emergency Communication system using more advanced technologies to directly disseminate warnings to vulnerable communities instantly, automating possible components of the warning dissemination process, increasing the number of early warning towers, increasing the human resource in the disaster management centre and establishing a specialized media department at the DMC to coordinate with the media were prominent. In addition, the necessity of improving response capability was highlighted.

H. M. S. S. Hippola, E. M. S. D. Jayasooriya, G. P. Jayasiri, Chameera Randil, Chamal Perera, K. K. K. Sylva, A. K. Kulathunga, C. S. Bandara, C. S. A. Siriwardena, P. B. R. Dissanayake

Gaps in the Evacuation of People with Special Needs During Coastal Disasters in Sri Lanka

Coastal hazards taken place all over the world have ended up with major devastations such as loss of life, property damage and environmental degradation more often. Sri Lanka, being an island in the Indian ocean is much vulnerable to coastal hazards; the unprecedented human disaster that caused by the Asian Tsunami was one of the worst examples. Present studies show that there are lot of programs carried out by the government and non-government organizations to drag down the adversity towards the coastal communities in the country who are much vulnerable to coastal disasters, focusing all the segments of basically social, economic and environmental aspects. Evacuation of coastal communities safely in disastrous situations is one of the main requirements within the disaster recovery framework. Having effective multi-hazard early warning (MHEW) systems and procedures in place in the coastal regions of the country helps to reduce the disaster risk. Although there are policies and practices for the evacuation of coastal communities including MHEW systems, the present study shows that the attention and preparedness towards the evacuation of people with special needs in the coastal communities is more or less omitted by the responsible parties. Moreover, when disasters strike, people with special needs meet various discriminations in terms of evacuation to a shelter or relief points and more often are overlooked from the emergency preparedness, response and recovery stages. Therefore, the present research focuses on determining the gaps in the evacuation of people with special needs in the context of MHEW systems during coastal hazards in Sri Lanka. Open interviews and telephone interviews were conducted in few major coastal cities and understood the likelihood of the obstacles, issues and the perception towards the evacuation of people with special needs. A questionnaire was developed according to the open interviews and fine-tuned in three sandpit events employing various local and foreign professionals in academics. The questionnaires were distributed online and the responses were analyzed. Eventually, a substantial number of gaps were identified in supporting the prevailing systems in Sri Lanka and was arrived at conclusions to impact the government through the findings in order to make the evacuation of people with special needs during coastal disasters more efficient.

E. M. S. D. Jayasooriya, H. M. S. S. Hippola, C. S. Bandara, A. K. Kulathunga, K. K. K. Sylva, P. B. R. Dissanayake, G. P. Jayasiri, Chameera Randil, Chamal Perera, C. S. A. Siriwardana

Community Environment and the Ecosystem


Multifunctional Landscapes for Urban Flood Management – A Study with Reference to the Kotte Wetland

Climate change, combined with the lack of drainage caused by urbanization contributes greatly to flooding in urban areas. With the intensification of urban floods in recent years posing a challenge to the development of cities, research is being carried out to focus on providing solutions for this global issue. Early research has concluded that the loss of wetlands which are natural flood detention areas has a notable effect on aggravating floods. Hence, it is evident that emphasis needs to be given to shifting to a landscape architectural approach of blue and green infrastructure, focusing on a multifunctional solution of integrating the landscape elements of land, wetland and water with environmental, social and economic benefits. Due to the socio-economical significance of the Colombo city, flooding is considered a significant hinderance for the city’s development. Several projects carried out around the Kotte marsh focusing on the Diyawanna Oya in Sri Jayawardenepura Kotte have attempted to address this issue through multifunctional landscape developments. This research investigates the effectiveness of these multifunctional spaces for flood management. The literature review identifies multifunctional landscape as the most significant solution with several principles and concepts under research. Through this, a theoretical framework is formed to measure the effectiveness of selected multifunctional landscapes. According to this study, multifunctional landscapes emphasize on sustainable water management in parallel to social responsiveness with the aim of making cities resilient to floods. The research was carried out through field studies, photographic surveys and mapping. It was identified that the landscape developments around the Kotte wetland included landscape elements which used materials and technology to create effective multifunctional spaces. However, it was concluded that the continuous decrease in natural flood detention would affect the large-scale flood resilience of the landscape in the long run.

D. N. Denipitiya, S. Udalamaththa

Single and Binary Adsorption of Heavy Metal Ions from Aqueous Solutions Using Coirpith as the Adsorbent

The adsorption of nickel and zinc ions onto coir pith was studied using batch experiments at 30 ℃ and 40 ℃. Adsorption kinetics and equilibrium isotherms were obtained for both single component adsorption and binary adsorption. The kinetics of single system and binary system adsorption of nickel and zinc was studied using Lagergren pseudo first order model, pseudo second order model and the intraparticle diffusion model. The experimental data showed all of the systems could be described using pseudo second order model. In the single system the coir pith had a higher capacity for zinc than nickel. In both the nickel and zinc single systems the adsorption decreased when temperature increased from 30 ℃ to 40 ℃. In the binary system at 30 ℃ the coir pith had a larger capacity for zinc adsorption then nickel but at 40 ℃ coir pith had a larger capacity for nickel than zinc. Equilibrium data were satisfactorily fitted to Langmuir and Freundlich isotherms. When comparing the adsorption capacity, qmax, the experimental data showed the binary system had a lesser capacity (qmax 13.6 mg g−1) than the single systems nickel (qmax 27 mg g−1) and zinc (qmax 22.7 mg g−1) under similar conditions. This suggests the competitive nature of the systems decreases the overall adsorption.

E. N. Ranasinghe, B. M. W. P. K. Amarasinghe

Sustainable Autarky of Food-Energy-Water (Safe-Water)

Urban wastewaters (UWW) are now being recognized as a resource, rich in nutrients and energy, rather than a waste stream that has to be treated and disposed of at the input of considerable energy and associated environmental emissions. This paper presents an algal-based approach for treating UWWs to the mandated discharge levels in a single step and at the same time, recover net energy, nutrients, and water from UWWs for use in the food-energy-water sectors. The proposed approach entails cultivation of energy-rich algal biomass in primary-settled UWW, followed by hydrothermal liquefaction of the resulting algal biomass to recover its energy- and nutrient-contents. Results from a pilot scale field demonstration project are presented to demonstrate the feasibility of this approach. The pilot scale study conducted at a local wastewater treatment plant confirmed that the discharge standards for biochemical oxygen demand (BOD), nitrogen, and phosphorous could be met with a batch process time of 3 days. Recovery experiments showed that more than 20% of the ammoniacal nitrogen (N-NH3) and more than 90% of the phosphorous (P) in the primary-settled wastewater could be recovered as struvite by the proposed process.

N. Khandan, D. Tchinda, S. M. Henkanatte-Gedera, I. S. A. Abeysiriwardana-Arachchige, H. M. K. Delanka-Pedige, S. P. Munasinghe-Arachchige, Y. Zhang

Study of Evidences on Chronic Kidney Disease Due to Unknown Etiology Based on Environmental, Social, Economic and Health Patterns of Selected Population

A Case Study Done at Wilgamuwa Area

Chronic Kidney Disease (CKD) is becoming a major rising public health problem in Sri Lanka. In addition, CKD has a very complicated interrelationship with other diseases. Accordingly, a community-based study was conducted to identify the evidences of the prevalence of CKD and correlate the relationship between drinking water and causes for CKD. Further, a study was conducted to identify the impact on lifestyle due to CKD issue. The study particularly focused on the Wilgamuwa Divisional Secretariat area where the burden of CKD is pronounced and the underlying cause is still unknown. The sample of the study was selected representing high and low prevalence of CKD which included both patients and non-patients. A questionnaire survey was conducted to gather data, mainly focused on areas like drinking water sources, social, environmental, health, economic, genetic and cultivation practices. Drinking water sources from the dug wells and deep tube wells used by both patients and non-patients was analysed for physical and chemical parameters including heavy metals. Water quality parameters like pH, conductivity, turbidity, oxidation- reduction potential and dissolved Oxygen were analysed onsite. Heavy metals were analysed from Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) and anions was analysed from Ion Chromatography (IC). Locations of water sources and patients and non-patients were traced by GPS and a groundwater quality and patient’s distribution map was prepared using GIS and a study of the patient distribution and causative factors interrelating the water quality was conducted. Based on all the water quality parameters and questionnaire survey results in the study, some of the dug wells in the area were identified as doubtful whereas some were suitable for drinking water. It can be concluded that there is no relationship with Hardiness and Fluoride with CKDU and most of the water quality parameters did not exceed the SLS drinking water standards SLS 614:2013.

S. M. Rajapakshe, S. K. Weragoda, T. Kawakami, W. B. M. L. I. Weerasekara

Algal Wastewater Treatment: Study of Polyculture in Fed-Batch Mode in a Winter Climate

Since the 1950s, reactors using algal-bacterial polycultures have been engineered by researchers to treat wastewater. The symbiotic relationship between algae and bacteria accommodates energy-efficient wastewater treatment by eliminating artificial aeration. Here, we investigated the applicability of a novel algal-based system using two polycultures to treat primary-settled municipal wastewater under field conditions in a winter climate (average daily temperature: 4–16.5 °C). The two polycultures were cultured in two closed 700L bioreactors deployed at a local wastewater treatment plant in Las Cruces, NM, United States. The Ammoniacal nitrogen and phosphate concentrations and OD750 of the two reactors were analyzed daily. The BOD5 in the reactors were analyzed once in two days. The samples from the two reactors were analyzed over 44 days from January to March in 2018. The culture in reactor 1 attained average ammoniacal nitrogen, phosphate, and BOD5 removals of 99.3%, 70.1%, and 70.0% respectively in a single step within five days. The corresponding efficiencies for reactor 2 were 44.3%, 47.5%, and 50.7%. The average batch processing times for reactor 1 and reactor 2 were 1.02 and 4.02 days respectively. This paper confirms the ability of both the polycultures to treat primary-settled wastewater in a single step.

I. S. A. Abeysiriwardana-Arachchige, W. Chapman, N. Nirmalakhandan

Comparative Study of Spatial and Temporal Variation of Drought Using Remotely Sensed Data - A Case Study for Kirindi Oya Basin

Droughts have turned out to be a standout amongst the most discussed natural hazards in the recent past due to its adverse impacts on humankind. The effects of drought differ from region to region and time to time. Unlike, the other cataclysmic events, a drought is a mind-boggling phenomenon due to its longer propagation time and the effects being long-lasting. This study focuses on analysing the spatial and temporal variations of the drought in the Kirindi Oya basin which lies in the intermediate, dry and arid climatological zones. Daily remotely sensed precipitation data for a span of 37 years from 1979–2017 has been used with a spatial resolution of 0.1°. Several drought indices, namely Standardized Precipitation Index (SPI), Deciles, Percent of Normal, Rainfall Anomaly Index and Z index have been considered. A comparative analysis of the applicability of each drought index along with the validation by ground reality is presented.The results of the study imply the importance of conducting a study at the sub-basin scale for the river basins lying in several vastly different climatological regions. The Kirindi Oya basin that is considered, lies in three different climatological regions, where the upper Kirindi Oya subbasin is in the intermediate zone, the lower Kirindi Oya in the arid zone and the rest in the dry zone. The results indicate that the effects of drought can vary even within a river basin and a sub basin scale analysis of drought gives a comparatively accurate interpretation of the variation of drought within the basin. Furthermore, the recent findings confirms that the drought prediction at a sub basin scale is more effective for river basins which lie in several climate zones.

S. U. Hendawitharana, M. K. D. D. Priyasad, R. L. H. L. Rajapakse

Potential for Formation of Trihalomethane in Diverted and Non-diverted Areas of Mahaweli River in Sri Lanka

Under the Mahaweli Development project the Mahaweli River was diverted to Rajarata area at polgolla barrage in 1976. Along the river concentration of the dissolved organic (DO), inorganic and suspended solids are gradually increased. In drinking Water Treatment Plants (WTPs) can be removed mainly suspended solid and some part of the dissolved component. As a result of remaining DO in filtered water disinfection by products (DBPs) formed such as Trihalomethane (THM) which is carcinogenic. This study was conducted to investigate THM formation potential in Mahaweli Diverted Areas (DA) and Non-Diverted Areas (NDA). Water samples were collected from following WTPs; Ukuwela, Matale, Dambulla, Bakamuna, Minneriya, Medirigiriya and 2- Ela as a DA and Meewathura, Greater Kandy, Pathadumbara, Mahiyanganaya, Dehiattakandiya, Gallella, Kantale and Mutur as a NDA. The raw water source of Ukuwela and Matale is Sudu Ganga and others are Ibbankatuwa Lake, Yoda Ela, Minneriya Lake, Kaudulla Lake and Parakrama Samudra respectively. Four THM species, Trichloromethane, Bromodichloromethane, Dibromochloromethane and Tribromomethane were measured using Gas Chromatography (GC) system and finally Total THM (TTHM) were calculated. The highest TTHM concentration was reported in 2- Ela (84.67 ± 35.17) µg/L and Mutur (83.85) µg/L which is exceeded the United State Environmental Protection Agency (USEPA) maximum contaminant level of 80 µg/L. Lowest concentration was reported from Matale 8.16 µg/L. According to the Kruskal-Wallis Test the median TTHM concentration of DA (22.73 µg/L) was not significantly different (p > 0.05) from the NDA (25.36 µg/L). The mean Conductivity (μS/cm), pH, turbidity (NTU) and alkalinity (mg/l) of the DA were 224.25 ± 65.95, 7.48 ± 0.36, 3.69 ± 1.91 and 87.5 ± 28.72 respectively and in NDA; 139.52 ± 62.39, 7.31 ± 0.37, 12.71 ± 12.13 and 56.25 ± 28.99 respectively. According to the statistical analysis there was no significant difference (p > 0.05) between the measured water quality parameters of DA and NDA.

H. R. L. C. Bandara, W. B. M. L. I. Weerasekara, S. K. Weragoda

Studying About the Manganese Phase Diagram When Manganese Is Reacting with Calcium Hypochlorite

Oxidation Reduction behaviour is highly contributes to the condition of the water. Oxidation reduction potential [ORP] gives an idea about the Redox behaviour of water while the pH value give an indication about the behaviour of the Hydrogen ion concentration. When Manganese is in water, it can exist either as particulate matter or as dissolved matter and this can be showed in Manganese phase diagrams. Due to the inconvenient consequences, Manganese should be removed from the water if only it has a higher concentration. For this, oxidation can be done by using Calcium hypochlorite and the obtained precipitate can be filtered. The behaviour of different Manganese species fluctuates with different pH values and Eh values. The objective of this study was to determine the effect of pH and Eh while changing the different concentration of Calcium hypochlorite to the blended Manganese solution which is prepared by using MnSO4. Final concentration of Manganese was reduced with lower concentration of Calcium hypochlorite and ORP values were reduced with the increasing pH. To conclude the result, Mn3O4, Hausmannite was obtain as the Manganese species according to the Manganese phase diagram.

S. A. Abeysinghe, S. K. Weragoda, W. B. M. L. I. Weerasekara

Watershed Characterization of Demodara Reservoir with Special Attention on Soluble Manganese Concentration

To ensure smooth operation and to manage water quality of the Demodara Water Treatment Plant (DWTP), better knowledge of its watershed is required. In line with this evolving response to water quality management; the National Water Supply & Drainage Board is currently piloting the development of a Water Safety Plan for the Demodara water supply scheme. For the purpose, watershed assessment as a baseline study in a border context for the study area is addressed in this paper. The DWTP is fed by the Demodara reservoir. Water quality tests were conducted representing its catchment and none of its water quality parameters except manganese (Mn) shows critical levels in the catchment. The catchment was analysed to capture the Mn source. Results show that the geological formation of the catchment consists of MnO2; especially in the Charnockitic gneisses layers. With rainfall, Mn+4 converts to dissolved Mn+2. It then comes to the Demodara reservoir from surface runoff and, it remains as Mn+2 at the bottom levels of the reservoir due to anaerobic, reducing conditions. Raw water is pumped to the DWTP from low levels of the reservoir, and therefore Mn enters in to DWTP system. Manganese chemistry is very complex and consists of multiple oxidative states. At the DWTP, Mn is converted to insoluble manganese by oxidation using KMnO4 followed by the removal of oxidized, insoluble manganese through filtration. However, manganese treatment does not completely remove all manganese from the treated water. It will allow some manganese to enter the distribution system, particularly in high rate water treatment plants. Literature reports emphasize that Mn has no negative health impacts at the levels commonly found in drinking water. However, aesthetic problems caused by Mn are a continuing source of concern for customers and DWTP operators. Therefore, treating Mn in raw water requires continuous monitoring by plant operators. For the smooth functioning of the DWTP, a number of recommendations are discussed in this paper.

W. G. Chathura Sanjeewa, R. A. C. B. Ranaweera, Ruwan Liyanage, W. B. M. M. W. Wijekoon, G. P. R. Ireshika

Application of Safety Plans for Rainwater Harvesting Systems in Sri Lanka

Water is often considered the most basic need for sustaining life. As the world population increases, the demand for quality drinking water increases. Dug wells and tube wells are considered as the main water source among the rural community in the dry zone. Rainwater harvesting is receiving increased attention in the dry zone as an alternative source of drinking water. While rooftop rainwater harvesting is being promoted, little attention has been paid to the quality of collected rainwater until recently. It becomes nationally important to look for low cost options which could be managed and afforded by the communities themselves. Rain water systems are categorized as individual systems and there are no proper regulations for maintaining the rain water harvesting systems. Therefore, it is vital to develop a proper guideline for rain water harvesting systems. Kebethigollewa was selected as the sample location due to the high number of rain water harvesting systems available. A questionnaire survey and focus group discussions with the beneficiaries were conducted to collect data on different rain water harvesting systems, rain water usage pattern and health concerns due to consumption of rain water. Based on the outcome of the data from observations, questionnaire survey and sample analysis, cost effective and community manageable rain water harvesting safety plan were introduced. Rain water was mainly used for the drinking and cooking purposes and dug well water was used for other activities like bathing and washing. Over hanging vegetation was identified above the roof catchment which may attract animals. Fallen foliage which blocked the gutters were identified in most of the guttering channels. According to the analysis, samples shows slight acidity. Turbidity ranged from 0.22 to 2.80 and TDS varied from 5 to 120 mg/l. All the water samples have TDS, Nitrate, Sulphate and hardness concentration below the prescribed limit.

K. A. I. L. Rathnayake, S. A. C. Upeka, K. A. M. Kularathne, P. G. K. B. Ranathunga, T. D. Jayasinghe, W. B. M. L. I. Weerasekara, S. K. Weragoda

Hardness and Fluoride Removal Efficiency of Groundwater: Use of Physiochemical Methods in Water Purification at Anuradhapura District Dry Zone in Sri Lanka

The limitation of drinking water critically affects the day-to-day life of most of the community in Sri Lanka as well as in the world. The community in the dry zone of Sri Lanka has especially been facing this difficulty for a long period. It is identified that high concentration of Calcium, Magnesium and Fluoride in groundwater is the main reason for this situation. Even though there are various methods used for water purification, the problem remains the same for rural communities and some urban communities. This study is focused on installing the most suitable and effective water treatment pilot plant and the collection of data to design an industrial water treatment plant. Anuradhapura and Mihinthale were selected as the study area based on the data collected during field visits. A pilot plant with a Reverse Osmosis (RO) membrane was installed and operated for two months of a time period, at the army camp Padulagama while comparing it with an industrial treatment plant at Rajarata University. According to the physical and chemical parameter results it was revealed that 32.43% of the raw water was successfully purified. Hardness and Fluoride concentration could be reduced up to 42.07 mg/l and 0.06 mg/l respectively. The common parameters which were reduced due to the use of RO membrane were also analyzed and found acceptable. Operation lapses and difficulties in treatment plants were identified and rectifications were carried out successfully. Designing of a RO water treatment plant with a pre-treatment unit and maintenance, regeneration and replacements were conducted. Recommendations were made for appropriate discharging methods of the rejected water from the RO membrane.

K. M. S. Kumara, K. A. M. Kularathne, P. G. K. B. Ranathunga, S. A. C. Upeka, D. C. Herath, S. K. Weragoda

Land-Use Planning Model: A Case Study on Transit-Oriented Development (TOD)

Many communities are shifting their land-use approaches by moving towards cities for better access to transportation and other facilities resulting in densification, particularly around main streets and urban centres. These trends are driving the increased emphasis on better models of city planning for urban centres, urbanization of suburbs of cities and crowding of either side of minor and major highways of Sri Lanka. Transit Oriented Development (TOD), is found to be a concept that has succeeded in reaching better sustainability for both society and the environment closer to the main transit access. The concept has been a success in the reduction of individual vehicle usage and the practice in the usage of the main transit systems which is in lieu of the concept of sustainability. In this milieu, this study was aimed at creating a TOD model for a developing city as a case study to verify the pros and cons of the concept of TOD in a context in Sri Lanka. A qualitative study was done with in-depth interviews to verify the complementary factors of a selected village in Sri Lanka to be converted to a TOD model as a case study. This paper presents the conceptual model on TOD for Meewatura, Sri Lanka.

G. A. M. A. S. B. Udapitiya, R. M. T. Rathnayake, K. K. K. Sylva

Effective Sizing of Natural Systems for Grey Water Treatment Using Locally Derived Parameters

When properly managed, grey water can be a valuable resource, which agricultural and horticultural practitioners as well as home gardeners can benefit from using to provide an excellent nutrient sources for vegetation. Natural treatment systems such as constructed wetlands emphasizing on sustainability and wastewater reuse typically for agricultural irrigation/home gardening can be considered as an ideal alternative to close the loop in terms of nutrient capture and water conservation. This paper presents a part of an analysis done to estimate the locally derived treatment wetland parameters based on BOD5 removal mechanisms of a pilot scale subsurface horizontal flow constructed wetland (SSHF CW) treating greywater. A pilot scale SSHF CW with a surface area of 8.64 m2 and a substrate depth (with 20 mm aggregates) of 0.7 m was monitored. This is a part of a long term study carried out to test the viability of SSHFCW for treating grey water for agricultural reuse. The wastewater flow measurements were taken from the inlet and the outlet of the constructed wetland while monitoring the hydraulic (HRT) and organic loading rates. Water samples from four sampling points were collected on a long term basis. Equations based on a kinetic model of a first-order piston flow reactor was used to calculate the relationship among the design parameters appropriate for local conditions. The HRT varied from 3.3 to 4.7 d for maximum and minimum inflow loading rates observed. Using the data from the current study, a resizing exercise for a subsurface horizontal flow constructed wetland was carried out. Accordingly, a household with four people, discharging 720 L/d greywater with an average influent BOD5 of 300 mg/L could be treated up a BOD5 concentration of 25 mg/L using an area of 3.60 m2 of SSHF CW, implying only 0.975 m2 of per capita land usage.

S. Karunaratne

Sustainability via ERP and BIM Integration

Sustainability is a paramount factor in the present construction industry which enhances the quality of life, thus allowing people to live in a healthy environment and improves social, economic and environmental conditions for present and future generations. Therefore, lots of construction companies have attempted to use different kinds of software for the development of sustainable structures. Two of those major software are Building Information Modelling system (BIM) and Enterprise Resource Planning system (ERP). This review seeks to identify how ERP and BIM addresses sustainability at the current level, a way of integrating BIM and ERP and how the integration of these two leads to sustainability of the projects according to the current literature. It is identified that there is a significant impact on sustainability by integrating ERP and BIM together than implementing them separately.

F. S. T. Hewavitharana, A. A. D. A. J. Perera

A Comparative Study of Speed and Flow Measurements Methods as Applied to Four Lane Dual Carriageway Roads

Flow-density-speed relationships play an important role in traffic flow modelling and provides basis to illustrate traffic flow behaviour under different traffic conditions. Analyses of this traffic condition critically depends on the collected traffic data. Traffic data collection under mixed traffic conditions is one of the major problems faced by researchers as well as the traffic regulatory authorities. Therefore a comparative study on traffic data measurement techniques has been carried out in this study. The traffic data can be collected using different kinds of techniques. In this study, traffic flow and speed measurements have been collected using a pneumatic tube detector method, video capturing method, moving observer method and manual classified vehicle counting method. By comparing these methods, suitable methods are suggested for application depending on the existing conditions. This study concentrated on traffic data collection along four lane dual carriageway roads and they are William Gopallawa Mawatha (AB42) and Gannoruwa road (B365). Along these roads, study areas have been selected such that traffic flow is uninterrupted. Tube detectors have been installed and data has been analysed using Metrocount software. For other methods data have been analysed manually. The flow measurements and speed measurements graphs have been obtained for each direction in both four lane roads. These graphs have been drawn such that they represent both forced flow conditions and free flow conditions. Comparison has been done suing graphs obtained.

W. U. A. Lowe, H. S. A. Mendis, I. M. S. Sathyaprasad

Green Technology and Energy


A Stochastic Differential Equation Based Wind Speed Forecasting Model

Stochastic differential equation (SDE) based approaches have demonstrated an improved capability in predicting temporal wind speed patterns that have statistical properties which are very similar to those observed in reality. However, no standard approach for deriving such models exist. One difficulty in arriving at a unified framework is the presence of a seemingly wide variation in the temporal statistical properties that one observes from location to location. In this work, we propose an SDE model for short term wind speed pattern predictions for Kokkilai, an area that is located in the North-Eastern coastal region of Sri Lanka. Here, we propose a systematic approach for modelling short term temporal wind speed variations, using a 1-dimensional stationary stochastic differential equation along with an approximated marginal distribution for the long term empirical wind speed distribution and the corresponding autocorrelation function. The model parameters were estimated to fit the empirical wind speed distribution of wind speed data that has been recorded at the wind measurement center of Kokkilai, from February 2015 to February 2016. The normal Gaussian distribution turned out to be the best fitted marginal distribution, in terms of maximum likelihood, for long term wind speed data. Then, an Ornstein-Uhlenbeck based SDE was obtained using the parameters of the fitted normal Gaussian distribution and the empirical autocorrelation function. Subsequently, considering special features such as cyclic behavior and certain trends of the empirical autocorrelation function, a set of new parameters were introduced to the drift and diffusion terms of the SDE. The obtained model was capable of generating a short-term wind speed forecasting trajectories that fall within an acceptable confidence level.

H. M. D. P. Bandarathilake, G. W. R. M. R. Palamakumbura

Experimental Investigation to Achieve Minimum Surface Roughness in Wire EDM Process

This paper presents the behaviors and evaluation of Wire Electrical Discharge Machining (Wire EDM) manufacturing process. Wire EDM is also known as Wire-cut EDM, which uses a dielectric fluid submerged thin metallic wire to cut the conductive work piece material. Taguchi orthogonal array was used for planning the experiments to optimize the control variables for better surface roughness while machining AISI 420 modified metallic material. Pulse-on/off Time, Wire Feed, Spark Voltage and Peak Current were selected as the control variables. AISI 420 metal, also called as Stavax®ESR has a higher metal strength and is used for all types of moulds and moulding tools in the industry. The experiments were carried out by changing the aforesaid control variable parameters and TR200 handheld roughness tester was used to measure the surface roughness of metal cuts. Three surface roughness measurements were taken for each machined section and averaged. Plotting method and Analysis of Variance (ANOVA) were used for the analysis and interpretation of the results. Error variances were estimated by using Pooling-up strategy. The influences of each control parameter on surface roughness were estimated. Then, the results were used to develop a mathematical model. The developed mathematical model can be used to minimize surface roughness. Control variable parameter settings for the optimized surface roughness can be obtained by using the mathematical model.

K. P. M. Priyankara, G. I. P. Perera

Eco-Friendly Porous Carbon Materials for Wastewater Treatment

Different porous carbon materials were applied to remove organic compounds and heavy metals from wastewater. Hierarchically, porous nitrogen rich monolithic carbon (HPC) was synthesized through the sol-gel synthesis method and carbonization process. Rice husk (RH), an agricultural waste material followed by carbonization at two different temperatures (RH400 and RH600) was used as the naturally generated porous carbon composite. Activated carbon (AC) was used as the control. According to the FT-IR spectra, different functional groups are present in all adsorbents. Scanning electron microscopic (SEM) images show an irregular shaped, random disordered macropore structure in RH and a robust sponge-like disordered macropore structure with ligaments in HPC. Transmission electron microscopic (TEM) images of these materials show a disordered mesopore network. Adsorption capacities of these porous carbon materials were determined for organic dyes and metal ions. Methylene blue and Methyl orange were used as the model organic compounds and Pb2+, Cu2+, Ni2+, and Cd2+ ions were selected as the metal ions. The experimental data demonstrate that the adsorption capacity of AC for Methyl orange (5.88 mg/g) is much higher than that of the alternatives (RH400–1.97 mg/g, RH600–0.69 mg/g, and HPC – 1.14 mg/g). Adsorption capacity of all the adsorbents for Methylene blue is quite similar. Adsorption capacity of RH400 for Pb2+ is much higher than that of RH600, AC and HPC. RH400 has a greater adsorption for Cu2+ and Ni2+ than the other adsorbents. All adsorbents show a low adsorption capacity for Cd2+. RH400 is a promising adsorbent for wastewater purification.

C. J. Thambiliyagodage, V. Y. Cooray, I. N. Perera, R. D. Wijesekera

Identification of Joint Efficiencies in 13 mm Finger Jointed Timber Species Used in Sri Lanka

When using timber in construction and the furniture manufacturing industry, waste timber materials and short length sections of timbers which are dumped by sawmills are considered to be matter of concern. ‘Finger joint’ is a recognized technique connecting two small pieces of waste timber together to ensure their sustainable utilization. Currently, the technique is used in Sri Lanka for non-structural purposes such as making timber boards and furniture. However, issues related with the strength of the joints have not fully investigated in Sri Lanka. This study was undertaken to determine the tensile strength performance of seven timber species in both unjointed (clear) and finger-jointed methods with 13 mm finger lengths and 4 mm finger pitch. An SWR adhesive (PVA) type was used as bonding material at normal exposure conditions. Well-seasoned Grandis, Jack, Kumbuk, Mahogany, Pine, Satin and Teak timber materials were used for the study.BS 373: 1957 and BS EN 15497:2014 were used as standards for tests. The tests for tensile properties were performed using the Universal Testing Machine (UTM 100 PC) with a loading plate moving speed of 01 mm/min. Maximum load was read on graph to calculate the ultimate tensile strength.The highest ultimate average tensile strength values were recorded in control specimens and different joint efficiencies were recorded in different finger jointed species. The highest mean finger joint efficiency percentage was obtained from Mahogany timber species and the least mean finger joint efficiency percentage was recorded in Kumbuk timber species.

C. K. Muthumala, Sudhira De Silva, K. K. I. U. Arunakumara, P. L. A. G. Alwis

Experimental Investigation of Top Hinged Flap Type Wave Energy Device with a Bottom Gap – Preliminary Experimentations

The “Pendulor” type wave energy converting system essentially consists of a caisson, a water chamber facing the offshore open, and a flap that is hung down in that. The flap is driven by the oscillatory motion of the standing waves generated inside the caisson. The flap then drives a generator through a hydraulic power transmission system. The main objective of the proposed study is to study the hydrodynamics of the device with a gap between the bottom of the flap and the caisson. As an initiative, this paper describes the test facility arrangements with wave tank modification, calibrations and preliminary model test results. Accordingly, the experimental facility, the wave tank at the Faculty of Engineering, University of Peradeniya was modified to comply with a scale models of (1/40) of the proposed device configuration for typical wave climatic conditions in which the wave length is 100 m, maximum wave height is 6 m and the power density is 20 kW/m.

L. U. Bakmeedeniya, S. D. G. S. P. Gunawardane

Increasing the Efficiency of a Dye-Sensitized Solid-State Solar Cell by Iodine Elimination Process in Hole Conductor Material

The use of silicon in photovoltaics are popular these days. Besides the use of silicon, the use of titanium dioxide as an n-type semiconductor material is trending in the emerging dye-sensitized solar cells due to its low cost, nontoxicity and ease in preparation when compared to silicon. The objective of this research is to find avenues to enhance the efficiency of a dye-sensitized solid state solar cell, fabricated using D-149 and N-719 dyes as sensitizers and excess iodine-eliminated cuprous iodide hole conductor. P-25 Degussa titanium dioxide in a titanium dioxide colloidal suspension was used to deposit titanium dioxide thin films with a thickness less than 20 µm on fluorine-doped tin oxide glasses. Titanium dioxide films were then immersed in the dye solution for 12 h to enable dye adsorption. Acetonitrile solution containing refined copper powder treated cuprous iodide was used to deposit excess iodine-eliminated cuprous iodide on to the working electrode. Optimum efficiency of 2.11% was obtained for the dye-sensitized solid-state solar cell fabricated using D-149 dye and 1.6% was obtained for N-719 dye. The highest solar parameters obtained were shown for the dye-sensitized solid-state solar cell fabricated for D-149 dye which were an open circuit photo-voltage of 475 mV and short circuit current density of 12.7 A cm−2.

A. W. M. V. Ekanayake, G. R. A. Kumara, R. M. G. Rajapaksa, A. Pallegedara

Monitoring Volatile Fatty Acids in an Anaerobic Process with Microbial Fuel Cell

Volatile fatty acids (VFAs) concentration is a good indicator to control and optimize the anaerobic digestion process. Though VFA concentration is a high sensitive parameter, most of the methods of measuring it are complex and require time. Therefore this study is to find out a reliable, quick method to monitor VFA concentration in the process. In this study, a microbial fuel cell (MFC) was developed using synthetic samples of VFA. As the first part of the study, the correlation between voltage and the acetic acid concentration in the anaerobic digestion process was developed using developed MFC. Microbes to digest the acetic acid were grown in the coir brush. That coir brush was used as a bio film in the MFC. The salt bridge, which is made using 1 M KCl and agar was used as a proton exchange membrane in the MFC. The relationship was observed between voltage and acetic acid concentration with acetic acid level from 0.09 M to 0.01 M.

H. M. K. S. B. Thennakoon, S. M. W. T. P. K. T. Ariyarathne, M. Danthurebandara

Embodied Carbon Reduction Strategies for Buildings

Global warming has become a major environmental issue faced by the international community. Greenhouse gases (GHG) have been suspected to be the source of global warming and carbon emission has identified as the main contributor for global warming. CO2 could be released due to activities carried out by human such as burning fossil fuels, electricity consumption and transportation. Hence, the carbon footprint is the total amount of greenhouse gases produced directly or indirectly as a result of an activity. Up to 40% of all energy have been consumed by the building sector and it has contributed up to 30% of global annual GHG emissions. Therefore operational and embodied carbon were identified as two main general groups of carbon emissions related to buildings. Numerous researchers have paid their attention on operational carbon reduction and there are limited study on embodied carbon reduction. Therefore the researcher aims to identify embodied carbon reduction strategies for buildings. After a comprehensive literature review, selection of low carbon materials at the design stage of the building, reuse and recycling of carbon intensive materials, material minimization, optimum building design, local sourcing of materials, transportation minimization, efficient construction processes, policies and regulations by government, adaptive reuse of buildings and carbon labelling schemes were identified as the global embodied carbon reduction strategies for buildings.

L. M. T. Kumari, U. Kulatunga, N. Madusanka, N. Jayasena

Sustainable Building and Infrastructure


Lessons to Learn and Challenges to Address in Resilient Historic Towns

The concept of resilient cities, including the environmental, social and economic dimensions of the urban sustainability against both slow and fast moving changes over long time horizons, is very distinctive when applied to historic towns. For built heritage, beyond the conventional goals, namely wellbeing and safety of citizens, functionality and reliability of services and infrastructures, effectiveness of management and development strategies, as well as availability of economic resources under disruptions or threads, a further aspect should be considered. It concerns the preservation and promotion of the original value and identity of the places by the capability to prevent, adjust and overcome the obsolescence at different levels – physical, technological, normative and functional. In this regard, two approaches are required: on the one hand, the critical understanding of the inherent qualities that made the historic towns resilient to past transformations – lessons to learn; on the other hand, the identification of strategies that could enhance such a resilient behaviour in the future against an exceptionally precipitous evolution of the outer alteration factors – challenges to address. In the light of the above-mentioned issues, the paper is going to develop some insights on the aspects that most influence the resilience of the historic towns, with specific attention toward the Mediterranean climate of South Italy. Firstly, some performance-based categories are identified, connected to the inherent resilience of the built heritage – e.g. relationships with the surroundings, employment of resources, natural regulation of microclimate, aggregation schemes and uses – as well as to the requirements of contemporary resilience – e.g. safety, accessibility, fruition, and efficiency. Thus, some qualitative and quantitative indicators are introduced and discussed, based on the validation by representative case studies, as a support toward the development of a resilience metrics for historic towns.

M. De Fino, E. Cantatore, A. Scioti, F. Fatiguso

Pedestrian Wind Comfort Study Using Computational Fluid Dynamic (CFD) Simulation

Many high-rise buildings are presently being designed and constructed in the central business district of Colombo. These buildings will change the wind patterns and directions which may create an uncomfortable environment at the pedestrian level. Urban authorities in many countries grant a building permit for a high-rise building, only if the wind comfort study proves that the wind environment for the pedestrian remains comfortable and safe. Pedestrian wind comfort and safety studies have been conducted in the past by wind tunnel tests. However, due to the high cost involved, pedestrian wind comfort studies are not generally carried out. With a significant improvement in computer resources in the recent past, Computational Fluid Dynamic (CFD) simulations can be used as an effective alternative method to simulate the pedestrian wind comfort around high rise buildings. This paper presents a validation of pedestrian wind comfort results obtained from a wind tunnel test, using CFD simulation.

Sarah Fernando, Shiromal Fernando, Priyan Mendis

Performance of Paving Materials in Outdoor Landscaping

Many developments today, have made the human lifestyle more comfortable but seem to be concerned only about the technical and economic viability rather than the environment or the user comfort. Hence, these developments are causing severe environmental issues such as global warming, heat island effect, losing the natural appearance etc. The selection of construction materials considering their properties is vital with respect to sustainable outdoor development. Materials such as clay bricks, asphalts, concrete etc.; are used and since recent times, concrete block pavements have become an attractive engineering and economical material in the construction of walkways, worldwide. However, there are many drawbacks with respect to user comfort via temperature effect in the use of these materials. Therefore, the study of temperature effects of materials, which are used for outdoor developments is important. Accordingly, this research was done to evaluate and compare the thermal performance of existing paving materials used for outdoor development in Sri Lanka. Separate sections were paved with different paving materials and same colour was applied on the surface to avoid the colour effect. The results obtained were evaluated and the thermal performances were compared. The results indicated that the material and its surface colour of surface influenced thermal performance.

G. H. Galabada, R. U. Halwatura

Determining Criticality of Performance Indicators for a Construction Company

Because of stiff competition in the construction business, it is necessary for construction companies to measure their performance on a regular interval for long-term survival. Therefore, it is imperative for construction companies to determine the parameters critical to the measurement of their performance. This study identifies the performance indicators, financial as well as non-financial, for construction companies to measure their performance. In a previous study, the authors identified a total of 20 performance attributes and applied principal component analysis which extracted six components called performance indicators. These performance indicators are profitability and asset management; key stakeholders’ satisfaction; time and cost predictability; environment, health, and safety; quality consciousness; and employee turnover. The present study utilized structural equation modelling (SEM) to determine the criticality of these performance indicators for which a questionnaire survey and structured interview approach were adopted. A total of 106 responses were collected from 90 different construction companies operating in various parts of India. The findings indicate that ‘quality consciousness’ is the most critical performance indicator whereas the ‘employee turnover’ is the least critical performance indicator in measuring the performance of a construction company. The performance indicators obtained from this study may help construction companies to measure and compare their performances with their competitors and setting out a strategy to remain competitive in the market.

K. K. Tripathi, K. N. Jha, A. K. Jain

Seepage in Iranamadu Dam and Its Influence on the Stability

Earth dams have played an important role in agriculture since ancient times. Failure of side slopes caused due to seepage or drawdown is one of the major considerations in the design of earth dams as the failure of a slope is catastrophic. The Iranamadu dam which was raised at different times showed a significant increase of seepage when the reservoir level increased beyond a certain elevation. In this research, the seepage problem of the Iranamadu dam was analysed using Geo-Studio (SEEP/W) software to estimate the seepage rate with the determination of the phreatic surface and to investigate the influence of the anisotropy of hydraulic conductivity of core material on seepage. For these analyses, volumetric water content function to be used in the unsaturated zone above the phreatic surface was selected from the van Genuchten model. Both steady and transient state seepage were carried out to compare the seepage rates with field measurements and the effect of anisotropy of hydraulic conductivity using the observed reservoir level history spanning over 170 days. Furthermore, the stability of the dam was assessed under seepage conditions using the SLOPE/W software. SEEP/W results show a good agreement in seepage rates with field measurements under both seepage condition when the reservoir level is above a certain elevation. Within a small range of reservoir level, some deviation of the predicted seepage rate is observed. Additionally, when the phreatic surface passes through the core section, a drop-in the seepage rate was observed due to the low permeability of the clay core. The seepage rate increased with ky/kx ratio and the Iranamadu dam seepage field measurements showed a good agreement when ky/kx ratio is 1. Therefore, the behaviour of the Iranamadu dam with respect to the seepage flow, shows a near isotropic hydraulic behaviour. The SLOPE/W results conclude that when the reservoir water level increases, the stability of the downstream slope reduced beyond the recommended value but the stability of the upstream slope was found to be satisfying the safety criteria under both steady and transient seepage conditions.

T. Venuja, L. C. Kurukulasuriya

Application of Principle of Network Connectivity in Creation of Sustainable Urban Form: Case of Negombo Water Fronts

City is a vital organism that entitled with the diverse planning attempts. Blue green infrastructure planning is the one of attempt which has been practised recently. Mainly the Blue Infrastructure Planning involves with the four major core principles of Green-Grey Integration, Network connectivity, multifunctionality and social inclusion. The principle of network connectivity has been considered in the research and it involves with the both structural and functional connections between blue green spaces in order to create added values from an interlinked system. Numerous quantative approaches have been developed to measure and map the connectivity. Measures of structural connectivity are based on the concepts of presence or absence or the size, form and shape of corridors. Initially, connectivity was calculated using the various indices of distance, frequency and density. The research finding has been adopted in Negombo Development Plan 2018–2030 which is formulated by Urban Development Authority. It adheres with the strategic planning approach with the use of diverse methods of multy criteria analysis techniques, field surveys, observation and key formal interviews to integrate the blue green spaces of the city with the purpose of enhancing the sectoral tourism, recreation and self-sufficient affluent city economy connecting the all blue spaces of urban waterfronts. The research attempts to find how the network connectivity influence to reinforce a sustainable urban form in the city and activate the networks of green and blue spaces with full spectrum of benefits to denizens and the journeyrs at all spatial scales that enable to open a positive platform to merge with the emerging urban challenges of the city and ultimately it influences to show the creation of sustainable urban form in Negombo with the integration of blue-green networks and considerable positive outcomes.

D. S. N. Jayakody

Development of a Post-tentioned Masonry Retaining Wall System

A Retaining Wall is a commonly used structural element in the field of construction. A retaining wall is a structure constructed to hold back any material (mainly soil) and prevent it from failure. A retaining wall is capable of resisting the material pressure of the material that it is holding back. Random Rubble Masonry (RRM), Reinforced Cement Concrete (RCC) and Gabion Wall (GW) are the most common types of construction materials used in the construction of retaining walls. RRM & GW are gravity type retaining walls and they require significant width from the land. RCC retaining walls require large amount of tor steel reinforcement, concrete and vertical form work, which are costly. Masonry walls such as brick walls and block walls cannot be used as retaining walls as they cannot withstand the tensile stresses developed due to lateral earth pressure. This paper discusses the development of a masonry block wall system which can be used as a retaining wall by post-tensioning eccentrically. The compressive stresses developed due to post-tensioning is used to neutralize the tensile stresses developed due to lateral earth pressure. This system eliminates concrete and vertical formwork and minimizes steel usage. It has advantages such as cost effectiveness, pleasing aesthetic appearance and simplicity.

W. W. P. K. Perera

Roads for Sustainable Cities – What Is Wrong with Us?

When ‘roads for sustainable cities’ are to be considered, firstly, the sustainability of roads should be brought into discussion. As an initiative, a road user behaviour study was conducted in a busy suburban area outside South-Eastern city limits of Colombo. The study area consisted of heterogeneous vehicle composition; typically combined with high proportion of motorcycles and three-wheelers which are poor in adhering to road rules that can commonly be seen in most South Asian developing countries. Although heavy investments are utilized in road improvement projects in these countries, the outcomes gained often seems to be unsatisfactory. The intent of this study was to find out the reasons for this unsatisfactory outcomes of the investments spent on road improvement projects and suggest measures to overcome these unsatisfactory outcomes for sustainability. The study was conducted in two parts; (i) road user behaviour study, and (ii) field consultation study. Through the road user behaviour study, the undesirable practices of all road users such as passenger vehicles, motorcycles, three-wheelers, buses, trucks, pedestrians and excessive noise were directly identified. It was seen from the consultation study results that the varied expectations of different categories of road stake holders were different from category to category and biased towards their advantage. Finally, through this study it was observed that the maximum benefits expected from investing on road improvement projects are not fully realized when poor road user practices are adopted by the stake holders’.

K. S. Weerasekera

A Sustainable Green Façade Retrofit for An Iconic Built Structure: A Case Study at SAINTGITS

The depleting fossil fuel reserves and the constantly surging levels of atmospheric pollution have made the architects and building owners join hands to foster sustainable initiatives. A modest experimentation in a sustainable domain had been inculcated at SAINTGITS, a much sought academic institution at Kottayam, in the state of Kerala, India. The campus houses multiple high rise buildings and a plenty of other small structures. The iconic structure, the Central Lecture Complex (CLC) exhibits its uniqueness with an arc shaped plinth which houses 3 stories to accommodate several conventional lecture rooms, faculty cabins, sophisticated seminar halls and other essential amenity spaces. It provides natural shade to the SAINTGITS Amphi theatre, structured and maintained at the eastern side. The proposed green façade retrofit on to the East and the West facing walls of CLC has improved the indoor operative temperature and hence, an approximate 15% reduction has been estimated in the building cooling load. An additional 2 m high temporary parapet wall has been recommended on to the existing CLC to provide extended shading hours to the SAINTGITS Amphi, right from 14:15 h onwards. The comprehensive acoustic modelling of the latter has given promising results for the Reverberation Time (RT60), which is on par with the international standards for performance spaces - ISO 3382-1 and ASTM E2235. The analyses inferred that the state-of-the art design of the existing CLC and the proposed green façade retrofits will reduce the entire energy demand by 20% and it certainly will provide guidelines to similar structures at tropical metropolises.

Jacob Thottathil Varghese, Sajan Thomas, Joselin Herbert

Embankment Construction on Power Blender Cement Mixed Soft Soil Treated Ground for CKE Bypass

Power Blender cement mix soft soil improvement method was adopted for the construction of embankment of the 4-lane bypass of Colombo-Katunayake Expressway for the New Bridge Construction over the Kelani River in Sri Lanka. This treatment method is a rapid construction method, first applied in Sri Lanka. The embankment height varies from 2 m to 5 m and peat/organic clay exists for a depth of about 10 m. Soil cement columns are spaced at 1 m × 2 m rectangular shape and the improvement depth is about 10 m. After completion of the ground treatment for the entire area and confirming the quality of the improvement, the embankment was constructed with 2 layers of geotextiles. During the embankment construction, settlement and lateral movement were measured. The expected settlements and lateral deformations were estimated and compared with field measurements. This paper describes the geological condition, embankment construction sequence, settlement estimate and stability analysis, measurement results and the comparison with the respective estimates.

N. Vasanthan, H. Ohashi, F. Obara, S. D. L. Tilak, M. C. W. Dissanayake, A. Karunawardena

Reinforced Concrete Bridge Deck Repair with Titanium NSM

The use of titanium bars as a near surface mounted (NSM) repair method for highway bridge deck slabs is investigated in this pilot study. Four full-scale slabs had half of their internal reinforcing steel cut resulting in an approximately 40% loss of slab capacity; these represented ‘damaged’ slabs. The objective of this study was to evaluate the performance of replacing these two cut bars in order to restore the original capacity of the slab. The four slabs were repaired using NSM titanium bars designed to restore either their capacity or stiffness of the cut bars. One slab from each group was repaired using a full-length straight bar while the other implemented a ‘staple’ type repair. Both approaches effectively restored the capacity of the slabs although each had significant impacts on the available ductility of the repaired slab. Repairs based on restoring lost bar strength resulted in preferable behavior. Restoring lost stiffness required four times as much titanium and resulted in over-reinforced sections showing little ductility.

S. L. Platt, K. A. Harries, M. J. McCabe

Physical Behavior of CFRP Retrofitted Reinforced Concrete Slab-Column Connections

Carbon Fiber Reinforced Polymer (CFRP) retrofitted application has become widespread in the last decade due to its unique advantages. This paper presents the punching shear strength enhancement of flat slabs which can be achieved with CFRP by embedding it through the slab section and attaching it externally on the tension surface. A common anchorage system that would optimise the use of CFRP has been introduced in CFRP shear reinforcement. The maximum capacity increment in punching shear was 22% and further improvements to achieve even higher load capacities have been discussed. Theoretical expressions have also been compared with the experimental results with recommendations.

R. H. M. Dissanayaka, M. A. L. Silva, L. P. G. Magallagoda, J. C. P. H. Gamage

Review on Fire Performance of Cellular Lightweight Concrete

Structural fire damage can be identified as a common accidental disaster throughout the world which cause thousands of deaths, injuries and millions in property damage each year. Fire represents one of the most severe conditions to which structures may be subjected. Generally, structural elements will be exposed to very high temperature (1200 ℃) during a fire propagation. Fire safety of a structure is measured in terms of fire resistance, which is the duration that a structural member can exhibit resistance with respect to structural integrity, stability and heat transmission. Concrete generally provides better fire resisting characteristics compared to the other construction materials due to its low thermal conductivity, high heat capacity and slower strength degradation with temperature. Cellular lightweight concrete (CLC) is one of the novel type of concrete which can be identified as a better construction material than conventional concrete due to its numerous advantages. However, limited research work has been carried out to determine the fire performance of CLC. Fire response of structural members depends on the thermal, mechanical and deformation properties of the structural material at elevated temperatures. Even though properties at elevated temperatures for normal weight concrete is available in literature, properties of CLC at elevated temperatures (ambient to 1200 ℃) is not thoroughly investigated. Further, CLC fire rating under natural/parametric fire situations and under hydrocarbon fire situations needs to be studied. EN 1992.1.2 provides minimum thickness requirements under standard fire situations for non-loadbearing and load bearing normal weight concrete walls, but for CLC, these values are not available, hence required to be included. Also, parameters and material property limitations related to spalling effect of CLC during fire exposure has not being investigated. Moreover, residual characteristics of CLC walls after fire situations and ability to withstand a second fire situation needs to be assessed.

I. R. Upasiri, K. M. C. Konthesingha, K. Poologanathan, S. M. A. Nanayakkara, B. Nagaratnam

Numerical Modelling of Re-cracking Behaviour in Retrofitted Crack Stop Holes in Steel Structures

This paper focuses on the delaying of crack initiation process in a crack stop hole (CSH) in steel structures. The cyclic J-Integral (ΔJ) numerical model was adopted to develop this study. Also, the Power law was applied to estimate the required number of cycles for crack initiation at the crack stop hole with the effects of carbon fiber reinforced polymer (CFRP) strengthening CSH improvement techniques. CFRP strengthened CSH indicated a significant improvement in the CSH. This retrofitting technique reported an optimal performance; in the range between 17.7% and 163.6% delay in required cycles for the crack initiation when compared to an un-strengthened CSH.

S. Abeygunasekera, J. C. P. H. Gamage, S. Fawzia

Comparison of Properties of Masonry Walls Constructed with Commonly Used Bricks and Non-standard Large Bricks

Brick masonry is a very popular construction material especially among the house builders, because of its better heat insulation properties, compressive strength, high durability, availability and the low cost. In Sri Lanka, brick masonry construction using commonly available burnt clay bricks (normal bricks), in different bond patterns can be seen in practice. However, the English bond is still considered to be the ideal bond pattern with normal bricks. Recently it has been noticed that a burnt clay brick with larger dimensions (non-standard brick) is gaining popularity in the local construction industry due to some advantages such as fast construction and reduction in the required mortar volume due to the reduced number of mortar joints. These larger bricks are used with a header bond pattern to build typical one brick thick walls. Although there are several benefits in using these larger bricks, it is important to determine the strength properties as well, since the strength of brick masonry highly depends on the strengths of brick units, mortar and the bond pattern. If these walls are used as load bearing walls or in-fill walls, the determination of strength properties is essential. The effect on strength properties due to the difference in bond pattern was addressed in this study. Experimental investigation was carried out to compare the strength properties of normal and non-standard brick units and corresponding brickwork in terms of compressive, flexural and shear strengths. Locally available normal brick and non-standard brick samples have been selected and tested according to the relevant standards to assess the strengths of bricks and brickwork. It was observed that the brickwork constructed with non-standard bricks has slightly higher compressive strength compared to brickwork with normal bricks. However flexural strength of masonry constructed with non-standard bricks with a header bond pattern is lower than the flexural strength of normal brick masonry which is constructed with the English bond pattern. Therefore, brickwork constructed with non-standard bricks is not efficient compared to normal brickwork, especially when the walls are subjected to lateral loads. This may be due to the weak bond in the brickwork constructed with non-standard bricks as the header bond pattern was used in them.

V. L. W. Seneviratne, D. Nanayakkara

Sustainable Maintenance of Steel Truss Bridges: A Conceptual Framework

This paper proposes a conceptual framework for the essential maintenance of truss bridges based on an accurate remaining fatigue life estimation technique. The framework mainly consists of structural appraisal based critical members and connections identification, remaining fatigue lives estimation of critical connections and time dependent member replacement or strengthening scheme. In the stage of critical member identification, detailed structural appraisal has to be conducted giving priority to visual inspection for condition, FE analysis, and material testing, experimental static and dynamic load testing. Accurate fatigue life estimation techniques of both members and connections consist of measured stress histories and recently developed new fatigue models. A verification of the proposed framework is conducted by comparing the predicted replacement scheme with a sequence of experimental failure and fatigue life of selected test specimens. Finally, the proposed framework was applied to a case study railway bridge to obtain time dependent member replacement scheme and obtained results were compared with previous estimations. Hence, validity and merits of the proposed framework were confirmed.

Sudath C. Siriwardane

Sustainable Manufacturing


Properties of Portland Blast Furnace Slag Cements Affecting Their Autogenous Shrinkage Behaviors

In Japan, Portland blast furnace slag cements that contain 30–60% of blast furnace slag (BFS) are classified in the slag cement class B in JIS R 5211. Even if slag cements are classified in a category, different autogenous shrinkage behaviors are observed among them. In this study, class B slag cements are collected from eight different plants in Japan. Physical and chemical properties of slag cements are investigated to find the cause of different shrinkage behavior. Physical properties of slag cement are expressed in terms of surface area, mean particle size and particle size distribution. The experimental results showed that the collected slag cements can be differentiated into two different groups based on physical properties. However, different behaviors of autogenous shrinkage cannot be explained, because slag cements, which contain finer particles, have not displayed significant differences in the shrinkage of mortar specimen. Therefore, chemical properties of slag cement could be the main reasons behind the different shrinkage behavior among slag cements. To compare the chemical property of slag cements, the phases of mineral (C3S, C2S, etc.) and content of cement and slag mineral (%) in slag cements are analyzed by thermal gravimetric analysis (TGA) and X-ray diffraction (XRD) Rietveld analysis. The results showed that in each plant, different types of BFS are used for producing the slag blended cements, and different quantity levels of slag minerals are found in BFS used in each cement plant. In slag cements classified as Class B in JIS R 5211, different physical and chemical properties are observed. However, the chemical properties of BFS in slag cement mainly influences the shrinkage behavior of slag cement. If the user of BFS cement is concerned about the shrinkage behavior of the concrete, the chemical composition of BFS should be checked to ensure that the concrete has sufficient resistivity against shrinkage.

S. Suntharalingam, Y. Takahashi

Fire Performance of CFRP Strengthened Steel I Beams Cured at Elevated Temperature

Elevated temperature curing increases the glass transition temperature of the polymeric bond between CFRP and steel. Fire performance of an elevated temperature cured and ambient temperature cured CFRP strengthened steel I beam was evaluated using a numerical model. The effects of a range of thicknesses and conductivities of insulation layers were also analyzed. Model results are in good agreement with the theoretical results. Insulation is a compulsory requirement for CFRP strengthened steel I sections. On average, a 35% increase in fire performance was noted at elevated temperature cured CFRP strengthened I beams compared to the ambient cured I beam.

E. R. K. Chandrathilaka, J. C. P. H. Gamage

Treatment of Wastewater with High Nitrogen Loading by Moving Bed Biofilm Reactor

Wastewater of municipal toilets contains higher nitrogen to carbon ratio than other types of wastewater. The removal of nitrogen from municipal toilet wastewater has become a major concern due to problems caused by discharge of insufficiently treated wastewater, such as eutrophication and toxicity. Moving Bed Biofilm Reactor (MBBR) has been developed in order to facilitate nitrogen removal. Treatment of nitrogen is commonly achieved in separate aerobic and anoxic tanks in typical MBBR systems. However the treatment process using a single MBBR tank as an advantageous method because of the low cost and low complexity, has not been thoroughly studied. This research is focused on the performance of MBBR in nitrogen removal based on simultaneous nitrification and de-nitrification in single aerobic MBBR with continuous operation. A moving-bed biofilm reactor system with an anoxic–aerobic arrangement was set up and the wastewater extracted from the wastewater treatment plant at temple of Tooth Relic, Kandy, was kept in the prepared laboratory set up for the accumulation of microorganisms. The operation was carried out in 3 steps. In the first step, the DO concentration in the reactor was maintained at 5 mg/l and the synthetic wastewater was introduced initially to the reactor at low nitrogen concentration. Then, the nitrogen concentration was increased varying the BOD/N. In the second step BOD/N ratio was maintained at 4.2, which is the BOD/N value of public toilet wastewater and the DO concentration was varied. Volatile Suspended Solids (VSS) of the reactor was kept at around 2200 mg/l. In the third step the DO concentration was maintained at 1.5 mg/l since it was the optimum DO concentration for highest de-nitrification in the 2nd step. Then the VSS of the reactor was maintained at 2200 mg/l and the BOD/N ratio was varied. Under the operating conditions, 67% of BOD and COD removal and 60% of TN removal could be achieved from the prepared laboratory set up. Further it was observed that the removal of nitrogen increased when the BOD/N ratio was increased.

H. K. D. T. Karunarathne, L. K. U. De Silva, K. B. S. N. Jinadasa

Experimental and Analytical Study of Residual Yield and Tensile Strengths in Partially Corroded Structural Steel

Corrosion has been one of the main structural degradation processes and has been the root cause of many engineering structural failures around the world. Therefore, proper understanding of corrosion process and especially residual strength measurement is an important consideration in the engineering discipline. This study was performed to find the residual strengths of partially corroded steel using a cost effective reliable method which can be adopted easily. For that, Average Weight Ratio (AWR) was introduced instead of the Minimum Thickness Ratio (MTR), proposed by previous researchers. In this context, partially corroded steel specimens were subjected to accelerated corrosion tests in a corrosion incubator. There, correlations were built between hardness verses AWR, ultimate tensile strength verses AWR and ultimate tensile strength ratio verses AWR of partially corroded steel.

P. A. K. Karunananda, K. A. D. D. T. Kariyapperuma, R. P. Weeraratne, H. D. M. Sanjeewani

Mathematical Modeling of the Hydrolysis Phase in Anaerobic Digestion of Solid Waste

Anaerobic digestion has been in use for many decades, and its range of uses keep on expanding although it has a reputation of being unreliable and unpredictable. Anaerobic digestion could provide a sustainable solution to waste disposal as well as power generation, if the process could be controlled as desired. This study was done in order to observe the behavior and to optimize the hydrolysis phase in anaerobic digestion of biodegradable solids, by developing a mathematical model for the process. Considering all aspects, a surface related model was used to describe the process since hydrolysis of complex solid substrates is dominated by surface phenomena. In order to narrow down the scope of the research, initial experimentation was focused on pure carbohydrates only. Boiled rice was selected as the substrate since it is readily available and because it is a pure form of carbohydrate. Through experimental data and the aid of the software Matlab2013, the model parameters were determined to be KS = −1 and rmax = 1.004 mmol/ under operating conditions of 1 atm pressure and temperature of 28 ℃. Further developments and improvements to this model are essential to be able to predict hydrolysis of complex substrates at any given operating condition. The improved model may someday result in a capable and efficient waste management system which is sustainable, ergonomic and efficient.

D. I. U. Edirisinghe, S. M. W. T. P. K. Ariyarathna, C. S. Kalpage

Design of a Robotic Firefighting Machine

The destruction of property and the environment by fires has necessitated the need for the design of an autonomous firefighting robot. Extreme cases of uncontrolled fires result in injury or even death. This paper presents a design for a firefighting robot with two degrees of freedom. The robotic arm will be able to direct a jet of water within a radius of 15 m. The ability of the machine to manoeuvre on its own, through the use of proximity sensors and flame finders reduce the risk of exposure to fire and smoke of the operator. The device is powered by two DC 40 Ah Lithium Ion batteries. At USD$3,455 initial value, the machine is estimated to depreciate to a value of USD$2,277.13 after five years, at a depreciation rate of 8%. The cost benefit analysis shows that the implementation of such a project is justifiable since having such a machine reduces the risk of losing properties and other valuables to fire. Despite the undisputed importance of fire, it can also be dangerous and costly if not handled well. Unwanted fires can result in heavy losses including properties and important documents. They can also cause injuries or even death. The use of an automatic machine (robot) to fight fire ensures less risk to firefighters at the same time increasing efficiency in putting out the fire. The use of robotics and control enhances accuracy and ease of operation of the machine. Careful design of each component guarantees fulfilment of the aim, which is putting out fire, with high efficiency and effectiveness. The cost of the machine is easily overshadowed by the privileges assumed due to its manufacture. The production of this machine thus ensures reduced financial losses and increased human safety.

R. Munzara, S. M. Ganyani, T. Mushiri

Design of a Portable and Sustainable Bicycle Frame

This paper is about designing a bicycle frame which is portable as well as sustainable for the nation of Zimbabwe. It is aimed at taking advantage of the properties offered by bamboo in the context of a bicycle frame e.g. ability to absorb vibrations when riding the bicycle on a rough terrain. Aspects of stiffness and ride quality are discussed in a detailed manner. There is also information on the three circumstances that affect a structure to work well. In this paper, frame materials like steel and carbon fiber are studied in view of how they have survived in the market and how those aspects can be incorporated in to the material bamboo to survive the market. Advantages and disadvantages of steel, titanium, aluminium and carbon fiber are viewed in a way to understand the impact of introducing bamboo as a material of choice for the nation of Zimbabwe. What makes up bamboo and its mechanical properties are also studied. The bicycle frame parts are also given attention to in order to view how they absorb force during the bicycle’s transit i.e. chain-stays, down tube, bottom bracket, seat-stays, top tube and seat tubes. How the tubes are to be joined is narrated in the methodology section. This is to answer the issue that in steel and other materials there is welding to join the tubes to form the bicycle frame; what about in bamboo bicycles?

T. Mushiri, R. Gumbo, C. Mbohwa

Design for Manufacture and Assembly of an Automated Dish Washing Machine

This paper was a research done at a local university in Zimbabwe. Dishwashing by hand involves scrubbing, rinsing and drying of dishes which is time consuming and laborious when done on a large scale. Each dining hall at the university uses about one thousand plates per meal and the university is understaffed thus the dishes are not thoroughly cleaned. A dishwashing machine is thus a necessity for the university. Researching of literature was done and information on the current designs of dishwashers, their operations, merits and demerits was gathered. A case study on the university was carried out using interviews and questionnaire. The dishwasher for the university was designed and it uses pressurised water jets to clean the plates. The pressurised water jets are produced by a pump installed in the dishwasher. The plates are put into the dishwashing using a rake conveyer system which is automatically controlled. The von Mises stresses of the system were analysed using Solidworks and they were in the desired range. Deflections were also done using Solidworks. Specifications and drawings of the dishwashing machine were developed. Materials of the design were selected concentrating on reduction of cost through minimising the number of parts retaining its function.

Tawanda Mushiri, Rutendo F. Solomon, Charles Mbohwa

Integration of BIM and Construction Supply Chain Through Supply Chain Management; An Information Flow Model

Building Information Modelling (BIM) is a revolutionary stride of technology in the orthodox construction and procedures in conventional Architecture Engineering and Construction (AEC) industry which is stressed upon for its delay on embracing new technologies. The strength of BIM has been disvalued in the eyes of many professionals, to think of BIM as just another ‘software’ which is in reality, a ‘process’ of attaining an outstanding collaboration among each and every stakeholder throughout a project’s life cycle. Hence, the philosophy of Supply Chain Management (SCM) in a construction project can be achieved effectively with the BIM’s promise of flexible and transparent interaction among Construction Supply Chain (CSC) contributors. However, the complexities in CSC of a conservative setup has been more composite with the intervention of BIM. Consequently, the BIM project stakeholders have encountered complications on the effective application of BIM on CSC while reaching the envisioned goals of BIM. Thus, the intention of this study is to develop a foreseeable information flow model related to construction supply chain in a BIM aided project. In order to attain the aim, an extensive literature synthesis was piloted to develop a conceptual informational flow model among CSC stakeholders of a BIM project. This contemporary research outlines that the CSC of a BIM project is much interactive and flexible with its collaborative effort of stakeholders when compared to the clashes among professionals in traditional setups. In a practical context, the roles and duties of BIM project stakeholders identified in BIM standards, have slightly differed due to real-world complications in construction industry. Besides that, BIM standards have laid down charismatic arrangements on information flows among BIM project stakeholders, which is in reality, a complex and random setup. Hence, the research outcome has successfully answered the complications by laying down guidelines for any outsider to the BIM field to recognise what would be the contribution of each stakeholder throughout the BIM project’s life cycle.

A. P. Rathnasinghe, M. K. C. S. Wijewickrama, U. Kulatunga, H. S. Jayasena

Removal of Heavy Metals from Industrial Wastewater Through Minerals

Heavy metals are toxic to the health and environment and causes harmful consequences to human beings. It is essential to take effective measures to remove metals from contaminated water. In this research, naturally available brick materials with different compositions collected from Kandy (type A), Gampaha (type B), and Embilipitiya (type C) areas were used to remove Cu, Cr and Pb ions. These brick materials are cost effective and are a readily available alternative to conventional heavy metal removal. The characterization of brick material is performed using X-Ray Fluorescence (XRF) and Nitrogen Adsorption – Desorption analyser. Calculated surface area and total pore volume and pore width of type A, B, and C are lie respectively, in the range of 128–154 m2/g, 0.24–0.45 cm3/g, and 5.6–16.7 nm. The main objective of this research is to investigate how the characteristics of adsorbents influences the adsorption process and to identify the best model to describe the kinetic and equilibrium adsorption to purify metal contaminated water. Results indicate that Pseudo – first – order kinetics model properly described the adsorption of Cu2+ to the brick type C, which has maximum adsorption capacity of 497 mg g−1. The adsorption process of Pb2+ to the brick type A and Cu2+ and Pb2+ to brick type B and C were well-fitted with Pseudo – second – order kinetics model. In equilibrium studies, the Langmuir isotherm showed a better fitness in adsorption of Cu2+ into brick type A and C, Pb2+ into brick type B, whereas the Freundlich isotherm well represented the adsorption characteristics of Cu2+ into brick type A, Pb2+ into brick type B and Cr6+ into all brick types. The comparison of results indicated that the use of brick types A, B, C can be used as a potential nan sorbent to remove heavy metals from industrial waste water.

U. A. S. L. Muthukalum, C. A. Gunathilake, C. S. Kalpage


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