Proceedings of the Canadian Society for Civil Engineering Annual Conference 2023, Volume 7

Road transportation is a significant source of greenhouse gas emissions in Canada, and the use of electric vehicles (EVs) is an effective approach to reducing these emissions. With an inductive power transfer (IPT) system integrated into road structures, EVs can recharge their batteries while driving, allowing for longer distances without frequent stops for recharging. While the energy efficiency of induction charging has been demonstrated, few studies have examined the effects of adding inductive charging coils on the mechanical behavior and durability of pavement structures. Therefore, an experimental study will be conducted using a heavy vehicle simulator (HVS) on a laboratory test pit to analyze the behavior of two pavement structures containing induction charging loops under critical climatic circumstances for cold regions. Said structures were built in the accelerated testing facility at Laval University. The test pit was divided into three sections, two of them containing an inductive charging coil (Sections 1 and 2), placed between the base and surface course layers, and the third being a standard Quebec pavement structure without inductive equipment. The surface course thickness of Section 1 is 7 cm, while the other two sections have a surface course thickness of 5 cm. All sections have a consistent base course thickness of 12 cm and were built with the same asphalt mixtures. All three sections were instrumented with multiple sensors: strain gauges, load cells, and temperature and humidity probes. The sensors were placed at various positions and depths during pavement construction to monitor the behavior of each component of the structures, from the surface course to the soil. The focus of this paper is to present the details of the construction and instrumentation of the test pit, which will be crucial for future accelerated loading tests and form the foundation for the development of design guidelines for inductive road structures in Nordic climates.

In an asphalt structure, mastic is the primary element that deforms. Many studies have been conducted to develop a rheological parameter that can assess the deformation and creep characteristics of asphalt mastic with varying proportions of fillers. However, only a few studies show the influence of Hydrated Lime (HL), Limestone (LS), and their combined effect (HL + LS) on the creep recovery performance of asphalt mastic with the combination of modifiers and anti-stripping agents. This paper employs the multiple stress creep recovery (MSCR) test as per AASHTO T 350 to understand the creep recovery properties of asphalt mastic. This study modified a neat PG 58-28 binder with Styrene–Butadiene–Styrene (SBS) or Gilsonite and Zycotherm as a liquid anti-stripping agent. Different filler-binder (F/B) ratios of HL, LS, and different proportions of HL + LS combined with SBS and Gilsonite modified binder containing Zycotherm were utilized to fabricate the asphalt mastic. Then, the Rolling Thin-Film Oven (RTFO) protocol was applied to simulate asphalt production time aging. The performance of these mastics was compared using non-recoverable creep compliance, stress sensitivity analysis, and MSCR percent recovery analysis. AASHTO M 332 specifications have been used to classify all the mastics based on the Jnr value at 3.2 kPa and stress sensitivity. In addition, polymer modification curves specified by the asphalt institute (AI) were employed to interpret the test results. According to the analysis of experimental data, the combined effect of 10% HL and 70% LS modified with SBS was observed to be predominant and satisfy all the creep recovery performance requirements.

Engineered cementitious composites (ECCs) are advanced materials with enhanced mechanical properties that have the potential to replace conventional concrete in the construction industry. The use of ECCs in RC buildings has numerous benefits, including enhanced ductility and toughness, which can lead to improved building performance in the face of natural disasters such as earthquakes and hurricanes. In this study, a nonlinear time history analysis was conducted using the Endurance Time method (ETM) to evaluate the collapse performance of an RC building with ECC beam-column joints. The ETM is an incremental dynamic analysis and is used due to its efficiency and reliable results in nonlinear analysis of the building. The collapse cost of the building was calculated using the FEMA P-58 method, taking into account both direct and indirect costs. In this study, this method has been applied using the intensity-based procedure, which considers seismic damages in different intensity levels to calculate the total loss of the structure. In the nonlinear modeling of the buildings, concentrated plastic hinges were used to model the nonlinear behavior of the elements, such as beams and columns. The use of concentrated plastic hinges allows for a more accurate representation of the actual behavior of the structure during an earthquake and can provide insight into the mechanisms of its collapse. The results showed that, while the maximum drift of the building increased due to high ductility, the collapse capacity was improved compared to conventional concrete. The use of ECCs in the beam-column joints significantly reduced the collapse cost and decreased the risk of injury to building occupants. The study highlights the potential of ECCs in enhancing the collapse performance of RC buildings and the importance of considering advanced materials in the design and construction process.

The high performance specified density concrete (HPSDC) is a type of concrete in which a certain proportion of coarse aggregate is replaced with lightweight coarse aggregate. This type of concrete is typically used in offshore structural applications where the wear resistance of concrete is an issue. The main objective of the current study is to provide a quantitative comparison between the properties of the HPSDC compared to the high performance normal weight concrete (HPNWC) and the high performance lightweight aggregate concrete (HPLWAC). The developed mixture incorporated using the optimum coarse to fine coarse aggregate ratio and the optimum maximum aggregate size for this concrete type. Hardened concrete properties were tested according to ASTM standard tests for mechanical properties and abrasion resistance. It was noted that the HPSDC had less but comparable mechanical properties to HPNWC. The HPSDC had less abrasion resistance by an average of 25% compared to the HPNWC. On the other hand, the HPSDC had higher mechanical properties compared to HPLWAC. It had also higher abrasion resistance by an average of 35%.

Traffic exhaust has had a negative environmental impact on society. This study aims to evaluate the use of nano-titanium dioxide in concrete pavement and its ability to purify the air from harmful gases such as NO_x. The nanoparticles are synthesized for experimental work including the STM test and Sonicator bath that were performed to the classification of the product. The method to produce TiO₂ nanoparticles yielded particles of size less than 15 nm. In order to utilize the photocatalytic properties of the produced particle, the air-purifying pavement blocks were poured into two layers. The top layer which contains the TiO₂ nanoparticles was designed to be pervious to allow the maximum reaction between the polluted air and surface area allowing the UV light to penetrate. The bottom layer consists of conventional concrete pavement components. Using a tailor-made experimental setup, a measuring device was used to quantify the air quality parameters in and out of the glass chamber. Three control samples were tested under the same circumstance and results were compared. The outcome of this study reveals that the use of nano-TiO₂ in concrete pavements reduces the percentage of NO_x in the air. Recommendations are made to enlarge the scale of the project to be implemented effectively. Ultimately, this study can be a step toward cleaner air and reducing the effect of climate change.

Fibres are generally incorporated into cementitious composites to improve its ductility and prevent shrinkage of the mixtures. However, most of the fibres used in cementitious composites are expensive and their production process emits a large amount of carbon into the environment. Recently, basalt fibres have been developed as a sustainable and economical alternative to fibres such as steel. However, most of the studies on basalt fibre reinforced concrete have focused only on the shrinkage and flexural properties of concrete, while other effects on properties on the air content and porosity are limited. In order to bridge this huge knowledge gap, this study was carried out to investigate the effect of basalt fibres on other critical properties such as air content, porosity and compressive strength of concrete. Observations from this study showed that the incorporation of basalt fibre into concrete increased its air content and porosity which consequentially affects the resulting compressive strength of the composite.

The new generation of multifunctional cementitious mixtures incorporating carbon fibers (CFs) with relatively low electrical resistivities is rapidly gaining importance in applications such as structural health monitoring and heated pavement deicing. In these mixtures, CFs are added to the paste, which occupies only a small volume fraction of concrete compared to that of the aggregates. Aggregates such as quartz and limestone that are commonly used for concrete production have high electrical resistivities. This can impede the electronic conduction in concrete mixtures and reduce the effect of the CFs. Increasing the paste volume of concrete has been previously proposed to overcome this issue. However, this method will increase the cost and greenhouse gas (GHG) emissions associated with producing concrete. In this regard, using conductive aggregates can provide a promising solution. This study aims to evaluate the effect of incorporating iron sand as the fine aggregate on the double percolation of mortars incorporating recycled CFs. The percolation of mortars incorporating up to 1 vol% CFs (pristine form or pre-dispersed) was investigated as the baseline. Iron sand was used to replace 25, 50, 75, and 100 vol% of standard quartz sand, separately and together with up to 0.6 vol% CFs. The synergistic effect of iron sand and CFs on the flow properties of mortars was studied through flow table test. The compressive strength (7-day and 28-day) and electrical resistivity (28-day) of the mortars were measured to evaluate the effect of CFs and iron sand as electrically conductive fillers in the mortar. The results showed that replacing standard quartz sand with iron sand reduced the electrical resistivity while maintaining the compressive strength and flow characteristics of mortars incorporating CFs.

India leads in global arecanut production. Arecanut husk remains as an unmanaged agricultural waste during the extraction of nut. The farmers are lagging behind in processing the husk and reusing it for various purposes. The research community is focusing on utilizing arecanut husk as reinforcement in composite materials to minimize the impact on the environment. The present study examines the physical and morphological properties of alkali-treated and untreated arecanut husk fiber. The physical properties of arecanut and its husk were investigated to evaluate the amount of fiber that can be extracted from arecanut. The fibers were extracted from arecanut husk by soaking in water for three days. The pH, acidity, and alkalinity of arecanut husk samples soaked in water were examined to know their utility in pest control. The extracted fibers were treated with 6% of potassium hydroxide solution to modify the arecanut husk fiber characteristics. The densities of treated and untreated arecanut husk fibers were determined. The effect of alkali treatment was studied using an optical microscope. It has been found that potassium hydroxide treatment improved the properties of the arecanut husk fiber.

The update of the volumetric guidelines used in the New Brunswick Department of Transportation and Infrastructure (NBDTI) is fundamental for the future of roads in the province. NBDTI divides their 22,000 km Highway Network into six districts, each with multiple contractors. This study is part of a project that aims to update New Brunswick Asphalt Concrete Specifications according to the present techniques and international standards, as some of NBDTI specifications date more than 20 years ago. A literature review was completed to gather the current specifications and experiences regarding asphalt mix design in several agencies in North America. These specifications were compared with the 2019 NBDTI Asphalt Concrete Specification (Section 261) and the American Association of State Highway and Transportation Officials (AASHTO) Superpave^TM Volumetric Mix Design Standards M-323 and R-35. It was found that currently NBDTI mix type WMA-B has the same nominal maximum aggregate size (NMAS) as AASHTO Superpave^TM 19; WMA-C mix has the same NMAS as AASHTO Superpave^TM 12.5 and, WMA-D mix has the same NMAS as AASHTO Superpave^TM 9.5. This analysis also showed that New Brunswick specifications have a much broader range in their control points than AASHTO. Mix designs between 2019 and 2021 revealed that even though most of the contractors met the requirements of the provincial specification, some did not comply with the AASHTO standard. Some mixes were selected along with NBDTI considering materials that had shown premature distresses in the past. The next steps in this study will include data gathering from the performance tests as a guide to an improved mix design, along with recommendations for conditioning specimens and testing parameters. The information of this project will contribute not only to the province of New Brunswick, but other agencies that are transitioning and updating their specifications for good-quality roads with higher resistance to common distresses such as rutting and cracking.

The purpose of this study is to evaluate the major influence of multiwall carbon nanotubes (MWCNTs) on the thermal conductivity of alkali-activated engineered geopolymer composites (AAEGCs). In order to serve the purpose, six ambient cured AAEGC mixes consisting of two types of powder-based activators, three (0, 3, and 6%) different contents of MWCNT, binary combinations (45% of ground granulated blast furnace slag and 55% of Class C fly ash) of industrial waste-based source materials, silica sand, and polyvinyl alcohol (PVA) fiber were developed using “one-part mix” technique. The impact of the combination of source materials, activators, and MWCNT dosages on the thermal properties of AAEGCS is evaluated and discussed based on temperature–time history, conductivity, and resistivity of concrete. The finding of the study showed that, during the thermal conductivity test, the AAEGC mixes’ temperature change increased when the MWCNT content of the mixes was increased from 0 to 0.6%. The thermal conductivity and diffusivity of AAEGC mixes increased with MWCNT dosages from 0% to 0.6%. Thermal conductivity of AAEGCs containing 0.3% and 0.6% MWCNT enhanced nearly 16% and 30% (for mixes with low calcium reagent type 1) and 18% and 46% (for mixes with high calcium reagent type 2), respectively.

A research study was undertaken to investigate the impact of Vinyl Acetate Ethylene (VAE) copolymer as an asphalt binder modifier with and without combination with Styrene-Butadiene-Styrene (SBS) copolymer. SBS has been used for decades to enhance asphalt binder performance, but the use of VAE as an asphalt modifier is not that old. The overall goal of this project was to determine the level of improvement achieved in the engineering properties of asphalt binder and mixture at low temperatures (well below freezing temperatures) due to incorporation of VAE/SBS copolymers. Low-temperature rheological properties of the modified binders as well as low-temperature resistance of the corresponding asphalt concrete mixtures were evaluated. Three different types of VAE and one type of SBS were used and blended at different levels into the base neat binder along with the designated dosages of VAE. Polymer modification was carried out in the lab such that the total modifier content (SBS plus VAE) would be 4.5% of the mass of the binder blend. The neat base binder used in this study was a PG 64-22. There was no change in the binder nominal low-temperature grade due to the VAE modifications, but the binders modified with higher VAE content exhibited an improvement because of lower stress sensitivity. The results also suggested that an advantage of replacing a portion of SBS with VAE could be notably recognized at the low temperatures in terms of stress relaxation. Replacing part of SBS with VAE, at 25% or more of the total modifier, expedited stress relaxation (i.e., resulted in higher m-value from Bending Beam Rheometer). Indirect tensile strength (IDT) was conducted at − 20 and − 10 °C to evaluate the cracking potential of the VAE-SBS polymer-modified asphalt mixtures at low temperatures. The results indicated that while a significant difference did not exist in the indirect tensile strength of the polymer-modified mixes versus the control mix, there was an improvement with respect to fracture toughness of the VAE-modified asphalt mixtures. This finding is in line with the results from the binder characterization, indicating improved resistance to low-temperature cracking due to usage of VAE.

The Grand Paris Express (GPE) is a project that aims to extend the metro network of Paris by creating four new lines, plus extending two existing lines. A total of 200 km of new tracks and 68 new stations are to be added, serving a projected 2 million passengers a day. Since it started, more than 20 Mt of earth is extracted, to which will be added until the end of the project in 2030. It is anticipated that the project will produce 30–40 Mt of excavated materials, which will primarily be transported out of Paris to be stored or buried in suitable areas. A potentially useful resource gets submerged in this process, which comes at a significant financial, economic, and environmental cost. Storage of those enormous, excavated materials is not sustainable, especially in a highly dense area. This paper explores the feasibility of using the excavated materials from the line 15 East as a building material. The detailed characterizations corroborate such a valorization. Expected benefits from recycling excavated disposal of GPE project include reduction of excavation management costs, reducing ultimate storage need, recycling of used materials, reduction of raw material requirements, positive CO₂ impact, and a positive societal impact through support for local employment.

The huge negative impact of the use of Portland cement as a binder in cementitious composites has called for an imminent need to develop a new binder system that can be used for different cementitious composites. The need to develop a new binder system is a result of the huge amount of emissions resulting from the production of Portland cement. For every tonne of Portland cement produced, there is a corresponding amount of carbon dioxide emitted into the environment. A novel type of mortar incorporating slag and glass powder as a binder and activated with sodium carbonate was developed in this study. The porosity and compressive strength of the mortar were investigated and a correlation between these properties and ultrasonic pulse velocity was derived. Results from this study showed that a structural grade mortar can be achieved by using slag and glass powder activated with sodium carbonate as a binder. However, there is a corresponding decrease in the compressive strength with increasing glass powder content in the binder system. Observation of the ultrasonic pulse velocity of the mortar showed that a non-destructive test can be used successfully to assess the properties of the novel mortar.

Climate change is a catastrophic phenomenon that negatively impacts the planet. Temperature variation is a major cause of climate change which results in melting glaciers and expanding waterbodies leading to increasing sea water levels. The Mediterranean coastline is at risk of flooding, shoreline erosion, and intrusion of seawater into the groundwater table due to the increase of seawater levels placing our coastal structures in danger. To alleviate the negative impacts of climate change, several preventive and remedial measures will be proposed and assessed using a simulation to compare them with the already existing conditions of a case study in Alexandria, Egypt. The objective of this study is to investigate the possibility of protecting coastal structures against the increasing effects of climate change by using an environmentally friendly, low-permeability concrete mix design to endure the chloride attacks in the sea water. Furthermore, soil injections using polyurethane will be analyzed to validate their effectiveness in decreasing the soil porosity protecting the structure’s foundations against the seepage of sea water into the groundwater as it rises. Several concrete mixes incorporating metakaolin, a pozzolanic material to reduce permeability, with 5 and 10% replacement of the ordinary Portland cement will be studied. Moreover, the potential use of geopolymer concrete consisting of fly ash, sodium hydroxide, and sodium silicate as a binder will also be assessed through three different mixes with varying molarities and alkaline-activator solution-to-fly ash ratios and compared to the metakaolin mixes. To evaluate the performance of the aforementioned mixes, several fresh tests as well as hardened tests were conducted. Results reveal that the mixes achieve superior mechanical properties when compared to ordinary Portland concrete, namely, higher compressive and tensile strength in addition to increasing durability. As for the early concrete properties, both the geopolymer and metakaolin concrete mixes exhibit a considerable amount of full strength during the first 7 days. Regarding the soil impregnation, polyurethane was successful in reducing the soil permeability by a thousand times. In line with the previous results, it was concluded that such actions are indispensable to alleviate the negative impacts of climate change.

In Canada, asphalt concrete is used in the construction of about 90% of pavements. A common practice used to improve the sustainability of flexible pavements through reducing their environmental impacts and cost over their lifetime is incorporating Reclaimed Asphalt Pavement (RAP) in the production of new asphalt mixes. Degree of Blending (DOB) between RAP and virgin binder plays a critical role in the performance of resulting mixes. Therefore, it is essential to quantify and understand factors affecting DOB to optimize the performance of RAP mixtures. The purpose of this study was to evaluate the effect of storage time at elevated temperatures, on enhancing the DOB in these types of mixes, using Attenuated Total Reflection—Fourier Transform Infrared (ATR-FTIR) spectroscopy and Dynamic Shear Rheometer (DSR). Different asphalt mixes were produced with 50% RAP, virgin HL3 aggregates, PG 58-28 virgin binder, and two bio-based rejuvenators. A gap gradation method was used to allow for easy separation of RAP and virgin aggregates after mixing, based on size differences. Control mixes (without rejuvenator) underwent four types of conditioning, 4 and 8 h at 135 and 110 °C. Based on the findings of the control mix, the rejuvenated mixes were exposed to two conditioning states, 4 h at 135° and 110 °C. Thereafter, the mixes were separated into RAP and virgin aggregates, and binder recovered from each separately. The recovered binder was evaluated using ATR-FTIR and high PG DSR testing. The results were used to estimate DOB and study the correlation between chemical and rheological properties. On comparing the test results the optimal storage time and temperature for maximizing DOB was found to be 4 h at 135 °C. It was also concluded that carbonyl indices showed a good linear correlation with high PG measurements.

Approximately 22 kg of used material (SPL) is generated per ton of aluminum produced. Untreated SPL is classified as hazardous industrial waste due to its hydroreactive nature and the presence of leachable cyanides and fluorides. After treatment with the Low Caustic Leaching and Liming (LCL&L) industrial process, the refractory portion of the SPL is transformed into an inert material called LCLL Ash. This project analyzed the potential use of LCLL Ash as a cement binder. The reactivity of LCLL Ash was evaluated by compressive strength activity index, Frattini and Rilem R³ tests, and X-ray diffraction (XRD) analysis. Inert materials (limestone filler, quartz powder) and conventional cement additives (fly ash, slag) were used as references. According to XRD results, LCLL Ash is composed of stable crystalline phases such as corundum, albite, nepheline, and contains graphite. In cement, LCLL Ash has inert properties, similar to quartz powder, with a retarding effect at early ages due to the presence of alkalis. Calcinating and addition of synthetic fluorite to LCLL Ash were explored as means to improve its reactivity. These methods significantly improved the reactivity by generating larger amounts of reactive amorphous phases with high silica and alumina content. The reactivity of calcined LCLL Ash was then similar to fly ash, without retarding effect, and showed compressive strength similar to cement at 28 and 112 days. A greater reactivity in cement pastes containing calcined LCLL Ash was also confirmed in XRD analysis by showing lower portlandite content and the formation of a new phase, rich in carboaluminate. These results demonstrate the potential for LCLL Ash valorization in cement, either as a filler or as a reactive cement additive after calcination.

Since it can negatively impact the intended service life, corrosion of embedded reinforcement in concrete is regarded as a severe durability risk for any reinforced concrete (RC) structures. Corrosion-induced early deterioration of RC structures eventually necessitates expensive repairs to get them back to serviceable conditions. Presence of chloride ion accelerates the corrosion process by removing the passivation layer of embedded steel making it a serious concern in the coastal regions. For rapid remedial action to be taken, early detection of an RC structure's propensity for corrosion is crucial. It is therefore important to monitor the extent to which chloride has permeated into the structure. Determination of chloride diffusion coefficient (D_rcm) by Rapid Migration Test (RMT) is a reliable method for evaluating the degree of chloride penetration susceptibility of an RC element which is a destructive and time-consuming method. The D_rcm values are widely used for evaluating the remaining service life of RC structures affected by chloride induced corrosion. Alternatively, half-cell potential (HCP) measurement is widely considered as a dependable non-destructive method to estimate the corrosion potential of RC structures and can be used to both assess corrosion resilience and identify corrosion likelihood. In this study, 36 unique mixes with varying proportions of supplementary cementitious material (0–40% replacement level of Ordinary Portland cement by fly ash or slag) and having different design strengths and slump values were submerged in 5% NaCl solution for 730 days (2 years). The corrosion potential and D_rcm of these mixes were observed and correlated. The outcome of the study provides scope for further research into developing a model for directly correlating the corrosion potential to D_rcm for predicting the service lives of RC structures under saline environment.

There is a high risk of chloride-induced corrosion of reinforced concrete (RC) in chloride-prone environment. Such corrosion of embedded rebars within concrete can drastically reduce the service life of the affected structure. Hence, evaluation of corrosion vulnerability of a RC element under vulnerable environment is necessary to ensure desired durability. The intrusion of chlorine ions in concrete occurs through the interconnected pores within concrete matrix. A high chloride diffusion coefficient of a concrete mix usually indicates a high intrusion susceptibility of chloride in the resultant RC element. One of the effective ways to reduce diffusion coefficient of concrete is through pore refinement that can be achieved by secondary hydration. The pore refinement breaks the connectivity of the pore network and eventually, hinders the intrusion of chloride ions. The secondary hydration is ensured by using supplementary cementitious materials (SCM) with active silica content. The Rapid Migration Test (RMT) is used to measure chloride diffusion coefficient of a concrete mix that requires specific test setup and preparation of test samples. The RMT is also a destructive test and time-consuming. As a result, conducting RMT experiments and finding chloride diffusion coefficients of a concrete mix is not always feasible. In this study, an attempt has been made to develop a correlation between relevant mix design parameters and chloride diffusion coefficients of the resultant concrete using Gene Expression Programming (GEP). GEP is an adaptive evolutionary artificial intelligence algorithm that uses evolutionary approaches on provided data and fits the data to generate an equation. Iterating the GEP program over a small set of data many times gives a good approximation. A total of 60 experimental RMT data has been utilized with mixes having wide ranges of SCM contents (fly ash and slag up to 40% level of replacement) and water to binder ratios. The developed correlation appeared to be quick and good estimation of diffusion coefficients that could be used as the basis for initial mix design process. Such assessment of diffusion coefficients would also assist in optimizing binder types and content for ensuring longer service life of RC structure in aggressive environment.

Ultra-high-performance concrete (UHPC) displays superior mechanical and durability performance. Additionally, it is more environmentally friendly than regular concrete and promises to be a workable option to increase infrastructure sustainability. The thermal performance of this type of concrete has reportedly become a subject that needs urgent consideration due to the rise in the utilization of UHPC in various infrastructure designs. This study aims to review the thermal properties of UHPC, including thermal conductivity, mass loss, specific heat, and thermal expansion. It also considers the factors that affect these properties, including exposure temperature, fiber addition, and coarse aggregate.

Asphalt cement is one of the most used road pavement materials due to its high road user satisfaction in terms of safety and comfortability. However, it possesses certain limitations such as its high carbon footprint and extensive maintenance costs over its lifetime, and hence, it negatively contributes to the environment and increases operational expenses. The aim of this work is to study the effect of incorporating waste-based geopolymers in asphalt binders on rheological properties based on multiple parameters including geopolymer composition, geopolymer percentage, and curing time. Two geopolymer mixes were prepared and comprised of combining raw materials fly ash (FA), metakaolin (MK), and silica fume (SF) with an alkali activator. The asphalt binder was modified with the geopolymer mixes by replacing the binder with 4, 8, and 12% geopolymer by weight of the binder. The modified binder was tested at different time intervals to investigate if the curing time of geopolymers inside the binder will improve the performance of the binder. Testing of the modified binder was conducted according to the Superpave testing procedures. The geopolymer-modified binder was examined under the dynamic shear rheometer, rotational viscometer, and bending beam rheometer machines. It is observed that the modification of the binder with geopolymers showed an increased performance with time. The FA as well as the MK-SF geopolymer-modified binders showed enhanced performance with respect to the virgin binder. Results showed that the binder sample modified with 12% FA geopolymer had a 31% improvement in high-temperature performance compared with the virgin binder and an 8.5% increase compared to the MK-SF geopolymer-modified binder. Both FA and MK-SF geopolymers had significant improvements in the low-performance grade with a 27% enhancement in performance compared to the virgin binder. Viscosity levels increased when modified with the geopolymer. This work provides an alternative to reduce asphalt binder in pavements which may consequently reduce carbon emissions and minimize landfill waste while enhancing the performance of the binder.

The impact of concrete on the environment has been a concern in recent years due to the significant CO₂ footprint associated with cement production. Thus, reducing such an impact is of paramount importance to reach the ever-challenging sustainability targets. Multiple studies have been performed to develop innovative mix design approaches that aim to replace cement with supplementary cementitious materials (SCMs) and mitigate the CO₂ emission. Yet, the industry is experiencing a limited supply of some of these SCMs such as fly ash. To overcome this issue, the present study aims to develop low carbon concrete solutions, ECOPACT, that incorporate alternative local Ontario materials, yield appropriate fresh and hardened properties, and have no impact on construction schedule. An experimental research program was designed to assess the possibility of reaching a minimum of 30% CO₂ savings in a wide range of concrete mixes. Results showed that the low carbon concrete samples tested in this study had similar fresh properties as the benchmark. In addition, the compressive strength of the low carbon concrete samples was comparable to that of the benchmark at later ages. Study results showed that developing low carbon concrete mixes with 30% to 40% of CO₂ savings is achievable, while satisfying performance, maintaining constructability and project aspects.

Engineered cementitious composites (ECC) are capable of exhibiting higher strain capacity which is several times that of conventional concrete. The micromechanics design on which ECC is based requires that coarse aggregates to be eliminated and a special type of fine aggregate which is called ultrafine silica sand to be used. The use of this micro-silica sand (MSS) in ECC mixtures is one of the major challenges facing the large-scale application of this composite due to its high cost. Also, as MSS is not locally available everywhere, its processing and transportation to construction sites result in carbon emissions into the environment. This ultimately leads to an increase in the overall embodied carbon of the composite. Therefore, the use of alternative local and/or recycled materials as aggregates in ECC will help to eliminate or reduce this detrimental effect of the production of ECC on the environment. This study was conducted to explore the potential of using recycled glass beads as aggregates in engineered cementitious composites (ECC), with the aim of enhancing their sustainability. Glass beads were tested as a partial or complete substitute for micro-silica sand (MSS) in ECC mixtures, and the composite’s performance was evaluated. The results revealed that incorporating glass beads into ECC improved its long-term performance. Additionally, under high alkali and temperature conditions, ECC containing glass beads did not exhibit any instance of the alkali-silica reaction.

Portland cement (PC) is a traditional binding material used in cement-based composites. However, the increasing detrimental effect of PC on the environment due to its production process has called for a need to use other times of binders in cementitious composites. The usage of alkali-activated binders has gained attention recently due to the total elimination of the PC as a binder. Alkali-activated binders are obtained by activating aluminosilicate precursors with alkalis. However, the high embodied energy coupled with the corrosive energy associated with the conventional activators used has limited the large-scale application of these types of binders. Therefore, this study was carried out to investigate the effect of green and user-friendly activators on the compressive strength of alkali activator mortar. The activators used are sodium carbonate, lime, and silica fume, and these activators are used solely and as binary activators. Results showed that structural grade strength can be achieved at 28 days with the use of these green and user-friendly activators. However, mortars activated with these activators exhibit lower early strength.

Polymers are widely used in various applications, such as coatings, adhesives, marine, and aerospace. In construction, synthetic resins are the most known polymers, commonly used as a matrix to reinforce carbon, glass, or other types of fibers. The high-growth use of synthetic resins has led to exploring the potential of an eco-friendly substitution. The biological, biobased, and bio-sourced resin is a product of renewable vegetable secretion in a solid or semi-fluid state. Biobased resins are translucent and meltable at low temperatures, insoluble in water, and challenging to crystallize. This study examines the differences in tensile properties between biobased resin, epoxy, and vinyl ester resins. These tensile properties are evaluated in two forms: (1) resin only and (2) carbon fiber reinforced polymers, with the three types of resins. The tensile strength, ultimate strain, and Young’s modulus are studied on: (a) 165 × 19 × 3.3 mm and (b) 300 mm × 25.4 mm specimens according to ASTM D638 and ASTM D3039 standard test methods. Test results showed that the biobased resin has a tensile strength of 47 ± 0.5 MPa compared to 54 ± 3 MPa for epoxy and 37 ± 0.7 MPa for vinyl ester. The results of Young’s modulus are almost identical: 2.6 ± 0.3 GPa for biobased resin, compared to 2.8 ± 0.5 GPA for epoxy and 2.3 ± 0.4 GPa for the vinyl ester. The tensile properties of carbon fiber biobased resin are tensile strength of 652 ± 33 MPa, a modulus of elasticity of 64 ± 6 GPa, and 1.3% ± 0.1 for the ultimate strain, compared to 1013 ± 103.31 MPa, 78.9 ± 6 GPa, and 1.92% ± 0.5 for carbon fiber reinforced epoxy resin, and 437.75 ± 90 MPa, 45.6 ± 8 GPa, and 1.01% ± 0.1 for carbon fiber vinyl ester resin.

Nanomaterials are well known to improve concrete microstructure and enhance fresh-state and hardened properties. This paper presents the influence of multiwall carbon nanotubes (MWCNTs) and reagent types on fresh-state properties of alkali-activated mortars (AAMs) and corresponding fiber reinforced alkali-activated engineered composites (AAECs). Ambient-cured AAMs/AAECs mixes are developed using the “one-part mix” technique incorporating two types of powder-based activators/reagents, varying contents MWCNT (0–0.6%), binary combinations of industrial waste-based source materials (such as: ground granulated blast furnace slag “GGBFS” and Class C fly ash), silica sand and polyvinyl alcohol (PVA) fiber. Fresh-state properties of AAMs are investigated based on mini-slump flow evolution with time and setting times while based on fresh density, slump flow, T₅₀ and slump velocity for AAECs. The influences of activator types and MWCNT dosages on fresh-state properties are analyzed and discussed. The study showed that increasing MWNCTs resulted in lower mini-slump flow and setting times. The reagent types also influenced the flow characteristics. Developed MWCNT-incorporated AAECs satisfied the criteria for possessing good flowability.

Physical tests allow for a thorough and detailed assessment of the overall performance of reinforced concrete structural systems. The complexity of certain experimental programmes, coupled with spatial and financial constraints, limits the ability to execute certain full-scale structural samples. To accommodate these constraints, scaled-down models are usually fabricated to provide a physical representation of the behaviour of the full-scale prototype. To yield results representative of the full-scale structural behaviour, a scaled-down model must follow similitude theory requirements, including the scaling down of material properties. In this study, a fine-grained concrete performance-based mix design is developed based on the material requirements for similitude theory. A parametric experimental study is conducted to examine the effect of the constituent materials on the overall mix and the one-day, three-day, and seven-day strength of the resulting concrete mix. The applicability of the proposed mix is assessed by analysing its individual material strength properties.