ICSBE 2020

Table of Contents

1. Sustainable Material and Manufacturing

   1. Frontmatter

   2. Application of Blended Cement Mix Pet Fiber High Strength Concrete for Structural Elements

      A. L. M. De Silva, T. M. Shakeer, J. T. Jayawardhana, P. P. C. Saumyasiri, M. S. T. Priyadarshana

      Abstract

      High strength concrete (HSC) is being produced due to growing demand for taller and larger structures and due to limitation of land space. Demand for HSC in Sri Lankan construction industry is now increasing due to Sri Lanka is a developing country. However, HSC has many versatile properties, there are some drawbacks. It is noticed that HSC is relatively brittle material possessing lower tensile strength and lower flexural strength. This study focuses on the experimental investigation to improve these drawbacks of HSC by addition of PET (Polyethylene Terephthalate) fibers. PET is a polyester polymer obtained from recyclable water bottles. With the development of technology in the modern world, the production of PET bottles keeps on increasing and they are being thrown after a single use, will eventually make environmental hazards. Further the recycling capacity in Sri Lanka is very low when compared to its production. PET fiber addition was done for water cement ratio of 0.25 and PET was added in 0%, 0.5%, 1.0%, and 1.5% of total weight of the cement. Then the compressive strength, split tensile strength and flexural strength were compared with the control specimens to know the effective usage of PET fibers. The results revealed that the presence of PET fibers will increase the HSC performance. PET fibers can improve the compressive strength, tensile strength and flexural strength and also to control the cracks. It was observed that 1.0% of PET fiber content exhibit better performance among all the mixes. The results showed that 21.75% of increase in compressive strength, 25.24% of increase in split tensile strength and 42.70% of increase in flexural strength for the addition of 1.0% PET fibers to the HSC after 28 days. These recycled PET fibers introduced HSC showed better performance compared to the conventional HSC.

   3. Use of EPS Based Light-Weight Concrete Panels as a Roof Insulation Material for NERD Slab System

      D. P. P. Meddage, M. T. R. Jayasinghe

      Abstract

      Natural energy sources are being ceased, due to the drastic development of various industries, along with the utilization of technology. Energy, related to the building sector has accounted for almost 23–50% of the world’s energy demand. Besides, reinforced concrete roof slabs have potential to contribute to this operational energy demand, acting as a heated body in the daytime. Therefore, our primary objective was to develop an energy-efficient slab system for low and middle-income families by adopting cost effective roof insulation. Accordingly, this study was directed in small scale physical models to investigate insulation characteristics of the EPS (Expanded Polystyrene) based concrete panels combined with NERD (National Engineering and Research Development) slab system. A parametric study was carried out using energy models, calibrated using the field results. Moreover, the thermal characteristics of this composite slab have displayed better results compared to prevalent roofing systems. The structural performance was assessed, in comparison to the conventional NERD slab system. This novel slab system performs well in tropical climatic conditions when it is installed with passive features. The overall decrement factor and the optimum insulation thickness were obtained as 0.6 and 75 mm respectively. Furthermore, the production of these insulation panels is an efficient way to dispose of non-biodegradable polystyrene waste.

   4. Effects of Carbon Black and Graphene Oxide Additions on Properties of Ordinary Portland Cement Composite

      A. M. B. Chandima, S. P. Guluwita

      Abstract

      Due to blooming of nanotechnology in the construction industry, various types of nanomaterials introduced to obtain ‘smart cement’. For the sustainable built environment, it is required to achieve durability and increasing the compressive and tensile strength of the construction structure. This research paper aims to provide a detailed investigation of the effect of Graphene Oxide and Carbon Black nanomaterials on hardening Ordinary Portland Cement (OPC) mortar, which uses in Ultra-High Performance Concrete (UHPC). The cost of UHPC is high due to micro reinforcements and with maintenance costs. The use of Graphene oxide is the aim of making smart cement, which can avoid cracking and corrosions, and it provides better monitoring of a concrete structure. Carbon black was incorporated in the optimizing stage of to reduce the cost factor. Mechanical and morphological properties were investigated by incorporating the cement mortar with 0.01–0.1 wt.% Graphene Oxide (GO) dispersion and with 0.1–1.0 wt.% carbon black (CB) dispersion of the cement weight. The test results revealed that the addition of 0.4% of CB and 0.03% of GO by weight is the optimal quantity of the composite, showing a 43.27% increase in compressive strength for specimens evaluated at the age of 2 days and 60.61% enhancement in the flexural strength for the specimens evaluated at the age of 28 days. Interestingly, it was observed that further addition of Graphene Oxide and Carbon Black reduces the workability and efficiency of the mechanical properties due to the restacking of excess Nano particles. Morphological analysis of the Graphene Oxide Cement Composite revealed that Graphene Oxide affected the formation of cement hydration products. Carbon Black nanoparticles in the Carbon Black Cement Composite act as the reinforcing and a filling ingredient of the cement matrix.

   5. Tensile Characteristics of Waste Based Natural Fibre Composites from Rice Husk and Low Density Polythene Waste

      P. M. I. B. Abesinghe, S. N. B. M. W. Y. S. Narayana, H. M. C. C. Somarathna

      Abstract

      Manufacturing new products with waste material has exposed a tremendous contribute to sustainable waste management globally. Recently, natural fibres have gained attention among researchers, engineers and scientists as an alternative reinforcement for synthetic fibre-reinforced polymer composites due to low cost, fairly good mechanical properties, high specific strength, bio-degradability and eco-friendly characteristics. This project was carried out to investigate the tensile properties of waste based Natural Fibre Composite (NFCs) with the use of Rice Husk (RH) as the reinforcement material and the low-density polythene (LDPE) as the matrix. five types of waste based NFCs were developed by varying the weight fraction of fibre to LDPE weight, and weight fractions considered in this study are 10, 20, 30, 40 and 50%. Simple techniques were used to manufacture NFCs, such as shredder machine and hot press machine which do not need high expertise. Uniaxial tensile test was carried out according to the ASTM D3039, using universal tensile testing machine with displacement control loading method. Load, displacement and time histories were obtained and further analyses were undertaken by obtaining Young’s modulus, yield stress, yield strain, ultimate tensile stress, failure strain, resilience modulus and toughness modulus for each variation. All types of NFCs with varying RH content show behaviour of materials having typical nonlinear elastic–plastic region. Research findings indicated that addition of 20–40% RH content provide better overall performance under universal tensile behaviour, by mainly considering the behaviour under elastic region and ultimate tensile strength.

   6. Development of Pervious Concrete by Using Bottom Ash as Supplementary Cementious Material

      L. C. G. De Silva, W. A. N. Dilrukshi, A. S. J. M. U. D. Jayasekara, T. Priyadarshana, M. K. Samantha

      Abstract

      Urbanization has reduced ground water level and flooding of roads due to extensive use of non-permeable paving method. To continue urbanization while preserving ground water and to mitigate street flooding will require a pervious concrete (PC). Although the pervious concrete has lot of environmental and economic benefits, its uses are still limiting in Sri Lanka. This research provides a background for developing a mix design using BA as a supplementary material and also achieving optimum balance between porosity and strength is essential with use of locally available materials. This study investigated the potential of using coal BA, waste product of coal combustion, as a substitute for sand which is scarce, in an optimum PC mix design. Concrete cubes 150 mm × 150 mm × 150 mm were manufactured in both mix design 1 (MD1) and 2 (MD2). In MD1 coarse aggregate replaced in 5–10 mm and 5–12.5 mm aggregate sizes with BA. In MD2 aggregate sizes of 5–12.5 mm and 14-20 mm studied in two separate arms by serial replacement of cement 0%, 7%, 12%, 15%, 20% and 30%. Compressive strengths were measured in day 7, 14 and 28. Effective porosity, permeability, flexural strength and abrasion have been measured. Cost analysis performed with the selected mix design versus conventional methods. Both 5–12.5 mm and 14–20 mm coarse aggregate mix designs—28-day percentage increase in compressive strength show linear increase and effective porosity inversely proportionate with the percentage replacement of cement with BA. In series replacement with BA both arms showed compressive strength inversely proportionate to percentage increase in effective porosity. Although it decreases the effective porosity with the percentage of BA, the effect on porosity is relatively lesser compared to the increase compressive strength. Optimum mix design of this study was concluded for PC as a paving method is 5–12.5 mm aggregate size with 12% BA replacement. When compared with the conventional paving methods, proposed PC mix design was cost-effective.

   7. Effect of Nano-Mg(OH)2 on the Mechanical and Flame Retardant Properties of Nano-Mg(OH)2-Ribbed Smoked Sheet Rubber Composite

      K. M. G. C. Bandara, M. R. Abeywardena, D. G. G. P. Karunaratne

      Abstract

      Polymeric composites incorporated with inorganic nanofillers have become a greater attraction in the modern field of material chemistry due to their improved properties. Yet flammability is a major drawback as the polymer materials burn easily. Nonflammable polymers made incorporating halogenated fire retardants cause several negative impacts such as emission of corrosive, toxic, and, smoky halogenated compounds. Magnesium hydroxide can be considered as a halogen free fire retardant. In this work, nano-Mg(OH)₂ was synthesized using the in-situ deposition method. Ribbed Smoked Sheet (RSS) rubber composites were made incorporating nanofiller in 5–12.5 phr loadings by compounding in the two-roll mill. The composites were tested for tensile strength, hardness, rebound resilience, compression, swelling index and, flame retardancy. Incorporation of nanofiller showed improved mechanical and flame retardant properties.

   8. Utilization of Coal Fly Ash and Bottom Ash as Raw Materials in Synthesis of Zeolites

      H. M. R. S. Herath, C. S. Kalpage, A. Manipura

      Abstract

      Continuous production and accumulation of coal ash in coal boilers has become a major economic and environmental concern. Transport of ash offsite for cement and concrete production seems economically unattractive. On-site value addition can be done if coal ashes could be converted to zeolites that possess high environmental applications. The present study was done to evaluate the possibility of converting coal ashes to zeolites. Coal ashes were subjected to chemical treatments to study the effect on material characteristics. X-ray fluorescence spectrophotometry results evidenced extraction of Al with alkaline treatment and extraction of Si with acid treatment proving the possibility of synthesizing zeolite X with alkaline treatment. Alkaline treatment followed by hydrothermal crystallization yielded 62% and 54% of zeolite from fly ash and bottom ash respectively. X-ray diffraction and Fourier transformation-infrared spectroscopy patterns of synthesized zeolites showed characteristics of standard zeolite X, verifying the formation of Zeolite X.

   9. Modification of a Bottom Ash Based Insulation Material Using Saw Dust, EPS and Aggregate Chips

      K. A. D. Y. T. Kahandawa Arachchi, J. C. P. H. Gamage, G. I. P. de Silva

      Abstract

      Bottom ash shows moderate properties of thermal resistivity when incorporated with conventional cement-sand plasters. This paper investigates the possibility of incorporating other commonly used insulation materials to develop a superior blend as cementitious insulation. Recycled EPS, sawdust, and aggregate chips were blended with a developed bottom ash based mix proportion and mechanical properties of the mortar were analyzed. Compressive strength, workability, and thermal conductivity were tested. The results indicated a 26% increment in thermal performance when EPS was introduced and a 33% increment when sawdust was introduced. On the contrary, their strengths reduced drastically. The aggregate chips had an inverse effect where thermal conductivity increased along with the strength. However, the compressive strength increased up to 75%.

   10. Modification of Engineered Cementitious Composite Mortar to Use as an Adhesive for CFRP/Concrete Bond

       M. W. C. Himasha, J. C. P. H. Gamage, G. I. P. De Silva, V. Attanayaka

       Abstract

       This study focuses on the development of a thermally insulative cementitious adhesive for bonding Carbon Fiber Reinforced Polymer (CFRP) fabrics with concrete using Engineered Cementitious Composite (ECC) mortar. The poor thermal performance of epoxy adhesive encouraged the development of a new cementitious adhesive which could resist elevated temperature. The ECC adhesive was developed using locally available materials. The developed adhesive has a low thermal conductivity between 0.145 and 0.18 W/(mK) which shows its resistance to elevated temperature. The developed adhesive showed an average bond strength of 570.28 N/mm² for an effective bond length of 150 mm. When compared with epoxy adhesive, ECC adhesive showed a 15% reduction in bond strength. However, under elevated temperature, the bond strength reduction in ECC adhesive is very low compared to the bond strength reduction in epoxy. When the bondline temperature was incremented up to 100 ℃, the strength reduction evident in modified ECC adhesive was 5.21%, while it was 69% for epoxy adhesive. It shows that the developed ECC adhesive resist high temperature better than epoxy. The average 28 days tensile strength of the adhesive was 3.83 N/mm² and the average 28 days compressive strength was 52.77 N/mm². A finite element model was developed and validated for the pullout test to predict the bond performance of ECC adhesive. The parametric study conducted varying the adhesive thickness concluded that the bond strength enhanced with the increment of adhesive thickness up to 20 mm.

   11. Assessment of Wood Properties in Lesser-Known Shorea spp. in Sri Lanka

       C. K. Muthumala, W. V. T. D. Amarasinghe, T. S. Mudalige

       Abstract

       Timber species, Beraliya dun (Shorea disticha), Navada dun (Shorea stupularis), Dun (Shorea zeylanica), Yakahalu dun (Shorea trapezifolia), Yakal dun (Shorea astylosa) and Thiniya dun (Shorea congestiflora) are lesser-known timber species belongs to Dipterocarpaceae family in Sri Lanka. Therefore it is important to identify these species and classify according to their timber properties to popularize among people engaged in the timber industry and forest management. In this study wood density, modulus of rupture (MOR), modulus of elasticity (MOE), compression parallel to grain (CNP) and compression perpendicular to the grain (CPG) of six Shorea timber species grown in Rathnapura district in Sri Lanka were investigated. The tests for mechanical properties were performed through the Universal Testing Machine (UTM 100 PC). Determination of the wood anatomical features especially vessels, rays and parenchyma with related to wood physical properties and density also investigated. To study the anatomical features, slides were prepared with small wood section and observed through the microscope using SE premium software and vessel diameter and ray measurements were measured. Six Shorea spp. were identified by using a prepared dichotomous key. The wood density was grouped into four classes as very high, high, medium and low respectively. Out of the six Shorea species, Shorea disticha shows the highest values for MOR and MOE tests and the Shorea trapezifolia was reported as the second highest values for MOR and MOE. Shorea trapezifolia has reported the highest values for CNP, CPG and Tensile strength values. According to the density values, the highest value shown by the Shorea trapezifolia and lowest was from Shorea zeylanica.

   12. Assessment of Hydrophobicity/Oleophilicity and Hydrophilicity/Oleophobicity for Autoclave Aerated Concrete Grains Coated with Stearic and Oleic Acids

       M. J. Zafar, A. Matsuno, H. T. T. Dang, P. T. Huyen, T. T. V. Nga, K. Kawamoto

       Abstract

       Oily wastewater is produced by the rapid urbanization, industrialization and economic growth in developing countries. At present, many oily wastewater treatment practices such as flotation, chemical coagulation, adsorption, filtration and membrane separation are available. Among them, oil/water separation techniques using natural hydrophobic/oleophilic (vice versa) and artificially modified solid grains have been paid much attention due to their cost effectiveness, quick treatment and sustainability but the potential use of hydrophobized porous grains has not been fully studied. This study aims to assess porous grains of autoclave aerated concrete (AAC) grains coated by hydrophobic agents (HAs) and discuss the applicability to oil/water separation technique. The AAC grains (0.106–0.250 mm) was prepared from waste scrap in Vietnam and were coated with two types of HAs, Oleic acid (OA) and Stearic acid (SA), at different concentrations. The degree of hydrophobicity/oleophilicity was assessed by measuring contact angles of water in air (CA_a) and oil in water (CA_o) in the laboratory. Results showed that the measured CA_a for both OA–and SA–coated AAC grains rapidly increased with increasing HA concentrations and reached the maximum of 140°–145° at HA ≥ 100 g/kg while CA_o decreased with increasing HA concentrations and the maximum CA_o values were 137°–140° at HA ≤ 10 g/kg. The correlations between CA_a and/or CA_o with organic carbon content (OC) and A/B ratio (ratio of hydrophobic groups to hydrophilic groups determined from FT-IR spectra) indicated that the measured CA_a for both OA- and SA-coated AAC grains increased with the increase in OC and A/B ratio and became a plateau (almost constant), while the measured CA_o showed a monotonic decrease with increase in OC and A/B ratio. In next phase, column filtration experiments shall be conducted for examining the oil/water separation efficiency and capacity based on the tested results of this study.

   13. Characterization of Water Retention and Unsaturated Hydraulic Conductivity for Recycled Road-Base Materials

       Ryohei Ito, Akira Kato, Akihiro Matsuno, Ken Kawamoto

       Abstract

       Not only characterization of saturated hydraulic property but also unsaturated hydraulic properties such as water retention and unsaturated hydraulic conductivity are necessary to evaluate an accurate water movement process and the design of water drainage in the road pavement system. Till now, only limited data is available for the unsaturated hydraulic properties for unbound roadbed materials due to the difficulty of measurement. This study carried out the measurements of water retention capacity (WRC) and unsaturated hydraulic conductivity for recycled concrete aggregates (RCA) that typically used for the road base and subbase materials. After grading particle size distribution of RCA adjusted to Japanese technical specification, the tested sample was compacted in a cylindrical mould following the modified Proctor method and then used to measure WRCs and unsaturated hydraulic conductivity. The WRC was measured under the main drying process by a combinational technique with a hanging water, pressure chamber, and a dew-point potentiometer and the unsaturated hydraulic conductivity was measured by an evaporation method. Besides, Toyoura sand was used as a reference material. Results showed the graded RCA gave a smaller water retention capacity compared to Toyoura sand at saturation, however, its water retention became higher than Toyoura sand at the suction range exceeding 10 kPa. As well as water retention property, the saturated hydraulic conductivity of graded RCA became smaller than Toyoura sand at saturation, however, the measured unsaturated hydraulic conductivities of graded RCA at the suction range of 10–100 kPa ranged in the orders of 10^–6–10^–8 cm/s and became higher than those of Toyoura sand.

   14. Proposing a Methodology to Identify the Optimum Mix Design of Autoclaved Aerated Concrete Blocks in the Context of Sri Lanka

       H. M. U. R. Herath, P. B. R. Dissanayake

       Abstract

       Introduction of Green Building Materials and Products (GBMP) results in a reduction of energy consumption over the lifetime of a building thus leading to a reduction in toxic, environmental pollution as well as ensuring the security of energy and raw resources as appropriate. The building construction industry has widely used fly ash based products as GBMP. Fly ash is a waste material generated from electricity power plants and is used in cement production with special properties such as workability and durability as well as in the production of concrete. However, in Sri Lanka, the industrial usage of fly ash is very low as compared to the high volume generated from the Coal Power Plant located in Norochcholai, Sri Lanka. This very wasteful, fly ash can be effectively used as a fundamental raw material in the manufacturing of Autoclaved Aerated Concrete (AAC) blocks—which are popular as light weight building materials. Using Autoclaved Aerated Concrete in Sri Lanka, facilitates two major aspects: Firstly, unused waste fly ash can be removed from the Norachcholai power plant premises in a sustainable way; Secondly, the Sri Lankan construction industry gains a sustainable building material. Nevertheless, there are certain issues in using fly ash based AAC in construction sites, such as its problem of drying shrinkage in the block which leads to cracks in constructed walls. The AAC manufacturing process is done in accordance with IS: 2185 (Part 3)—1984, but raw material sources are not providing the required qualities according to the code. Although the raw materials are not providing the required qualities for the production process it is a must to use available sources in Sri Lanka. This question can be addressed by optimizing the mixture design for the available materials in Sri Lanka, considering its drying shrinkage and compressive strength, stays within the limits given in BS EN 771-4:2011+A1:2015 Specification masonry units Part 4. Eleven different mixture designs were prepared by varying fly ash, cement and lime, subsequently tested and thereafter, an equation to calculate drying shrinkage and compressive strength was formulated as a function of fly ash cement and lime. Using the results of this research, optimization of the mixture design can be done in the AAC manufacturing plant.