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Expansive clay soil is known to cause damage to pavements due to its volume fluctuations with changes in moisture content, a phenomenon observed globally in many countries. Implementing suitable stabilisation treatments is crucial for improving the mechanical and hydraulic properties of the expansive clay subgrade. While cement and lime have traditionally been widely used as soil stabilisers, there is a growing emphasis on sustainable engineering due to increased awareness of global warming. Seeking alternative green and sustainable materials for soil stabilisation is demanded now, and one such alternative is using ethylene-vinyl acetate (EVA) copolymer emulsion. However, the use of EVA copolymer emulsion for stabilising expansive clay has been relatively underexplored in existing studies. This study evaluates the feasibility of utilising EVA copolymer emulsion for stabilising expansive clay subgrade through comprehensive laboratory tests to assess the mechanical (compaction, unconfined compressive strength, California bearing ratio, resilient modulus, and direct shear), hydraulic (soil-water retention curve and swell-shrinkage), and micro-chemical (thermogravimetric analyses and scanning electron microscopic) performance of the soil. The experimental results indicate that the inclusion of 1 % EVA copolymer emulsion into the expansive clay provided the highest mechanical properties, resulting in an increase in the unconfined compressive strength, soaked California bearing ratio, resilient modulus, and cohesion by 8.8 %, 177.8 %, 35.8 % and 19.4 %, respectively. Swell-shrinkage behaviour was also improved with the addition of EVA copolymer, with 1 % EVA copolymer presenting the lowest swell-shrinkage index of 3.19 %/pF (14 % decrease in shrink-swell potential compared to the untreated clay).

Building upon our pioneering laboratory research on coffee biochar in concrete, this study presents a world-first field trial, translating lab-based findings into real-world construction applications. Our previous experimental work demonstrated that biochar derived from pyrolysing spent coffee grounds (SCGs) at 350°C, when used as a partial replacement of fine aggregates, could enhance concrete strength by up to ∼30 %. This field study evaluates the performance of coffee biochar-enhanced concrete under actual construction and environmental conditions. However, a major limitation was encountered in the production of coffee biochar, as the pyrolysis equipment of the commercial-scale biochar producer could not operate at the optimal 350°C temperature due to operational constraints. In this real-world application, we collaborated with a local council to translate the lab-based research work into a mainstream construction solution. To evaluate the performance of this biochar blended concrete, we carried out independent testing of the concrete slump, compressive strength of concrete and cored slab, flexural strength and concrete shrinkage and compared its performance against the control mix. The successful translation of this lab-based research into field applications showcases the potential of coffee biochar as a sustainable construction material that can transform coffee waste into a valuable resource for concrete applications with improved performance. It also highlights the current supply chain limitations that must be addressed before making it a mainstream construction material.

Due to the environmental issues associated with the production of binders such as cement and lime, finding alternative materials or binders for geotechnical applications is crucial. Therefore, developing low-carbon-footprint cementitious materials by replacing cement and lime with recycled waste-based geopolymers can provide environmental and economic benefits. Incorporating recycled waste materials or green binders in soil stabilizations can not only reduce the construction cost and alleviate environmental issues, but also improve the mechanical properties of the soils. Although the idea of using recycled glass powder (RGP) as a reclaimed material for stabilizing clay soils is not new, the adoption of copper slag (CS) or combination of CS and RGP for the treatment of low-plasticity clay soil has rarely been studied. In this research, various molarities of sodium hydroxide as an alkaline activator and different combinations of CS-RGP were used to assess the mechanical and microstructural behavior of the stabilized low-plasticity clay soil. Moreover, the effects of two different curing conditions (i.e., oven-dried content (DC) and optimum water content (OC)) and curing time on the mechanical properties of the soil (i.e., unconfined compressive strength and California bearing ratio) were evaluated. The results clearly indicated that CS influenced Atterberg Limits and compaction parameters more than RGP. Also, it was observed that by applying 5% CS at a fixed alkaline activator, the UCS at 56 curing days and CBR at 7 curing days increased 3.11 and 1.68 times, respectively, while these values were 4.03 and 1.90 times, respectively, by applying 5% RGP.

Expansive soils swell when they absorb water and shrink by losing water. This process causes significant volume changes in highly expansive clay soils. Clay soil foundations have caused problems for various civil engineering projects, including pavements, railroads, embankments, and foundations worldwide. Besides, the accumulation of huge amounts of waste glass is responsible for several environmental issues. Although the idea of using waste glass for pavement application is not new, the adoption of waste glass for the treatment of highly expansive clay soil as the pavement subgrade has been rarely studied. Previous studies in this area mainly adopted powdered glass, glass fine, glass residue, and soda-lime glass powder, which are costly to produce. In this study, 5 mm minus crushed glass was added to the expansive clay subgrade at different percentages (0%, 5%, 10%, 15%, and 20% by dry weight of the clay). Comprehensive series of mechanical and microstructural analyses have been conducted in this research. The results show that the inclusion of crushed glass into expansive clay, as a pavement subgrade material, significantly improved the mechanical properties (i.e., unconfined compressive strength, California bearing ratio, and resilient modulus) and reduced the swelling and shrinkage potentials and improved the soil-water retention properties of the clay. Crushed glass also enhanced the flexibility/deformability of the subgrade expansive clay soil. The improvement of the properties of the clay subgrade with crushed glass was also supported by the X-ray micro-tomography and SEM analyses. According to the test results, the addition of 10–15% glass was found as the optimum content.

Single-use isolation gowns have become an important practice across medical centres, testing sites, and emergency rooms since the onset of the Coronavirus pandemic; within the later months of 2019. Although reusable isolation gowns have proved beneficial, 80% of frontline centres opt for disposable isolation gowns, increasing the demand for plastic-based personal protective equipment (PPE) and the environmental strain from excess waste in landfills. This research aims to explore the practicability of using plastic-based isolation gowns in structural concrete to scale back the quantity of pandemic-generated waste ending up in landfills. The shredded isolation gowns were added to aggregates at 0.01%, 0.02%, and 0.03% of the volume of concrete. The effects of various concentrations of shredded isolation gowns on the mechanical properties of the concrete were investigated through a series of experiments alongside an SEM-EDS analysis. Results demonstrate an enhanced bridging effect between the cement matrix and shredded isolation gowns, allowing for the steady trend of improved mechanical properties with increases of 15.5%, 20.6%, and 11.73% across compressive strength, flexural strength, and the modulus of elasticity, respectively.

Expanded polystyrene (EPS) is currently being utilized in sustainable materials owing to its ultra-low density and superior thermal performance. It can be incorporated in concrete mixtures to replace coarse aggregate to produce lightweight aggregate concrete (LWAC). Concerning the high shrinkage development in LWAC, the present study reviews the available published articles regarding the drying shrinkage of lightweight concretes containing expanded polystyrene. According to the previous studies, the drying shrinkage development in expanded polystyrene concrete (EPSC) has been reported to be greater than that in conventional concrete, which must be considered for its application in the construction industry. It is mainly attributed to the low elastic modulus and mechanical properties of the EPS. However, incorporating additives and fibers can improve its shrinkage resistance properties. A comprehensive comparison of drying shrinkage magnitude between various LWAC showed that the drying shrinkage strain of EPSC is not generally higher than other types of LWAC; however, the density of EPSC was measured lower than that in other types of lightweight aggregate concretes.