Advances in Science and Technology Vol. 180

Abstract: The increasing volume of solid waste and the environmental impacts of cement production have prompted the exploration of sustainable alternatives in construction materials. This study investigates the feasibility of incorporating paper and pulverized shell wastes as additives in cement-based, non-load-bearing brick production. Specifically, the research evaluates the effects of varying shell-to-cement replacement levels (5%, 10%, and 15%) while main-taining a constant 1:1:3 ratio of cement, sand, and paper pulp. A total of 27 brick specimens were fabricated, with three samples per mixture design tested at curing periods of 14, 21, and 28 days. Compressive strength testing was conducted in accordance with ASTM C90 standards. Statistical analysis, including two-way ANOVA and Tukey’s HSD post hoc test, was employed to determine significant differences among mixture proportions and curing du-rations. Results indicate that curing time and shell percentage significantly influenced compressive strength. The highest average compressive strength of 1,993 psi was achieved at 28 days with 10% pulverized shell replacement. This value approaches the minimum requirement for load-bearing masonry units, indicating borderline load-bearing performance. Furthermore, cost analysis revealed that bricks incorporating paper and shell wastes demonstrated notable cost savings compared to conventional cement bricks. Overall, the findings suggest that the integration of paper and shell wastes in brick production presents a viable and cost-effective approach to reducing cement consumption while promoting waste valorization and sustainable construction practices.

Abstract: The rapid growth of the e-commerce sector has led to a surge in Low-Density Polyethylene (LDPE) waste, specifically in the form of post-consumer Air Bubble Film (ABF). This research investigates the valorization of ABF as a reinforcing agent within a Polyvinyl Chloride (PVC) matrix to develop sustainable sheet piles for flood mitigation. Polymer blends were fabricated at PVC to ABF ratios of 90:10, 80:20, and 50:50, utilizing a 15% weight constant of Chlorinated Polyethylene (CPE) to enhance interfacial compatibility. Mechanical characterization, conducted via a minimum of five trials per ratio to ensure statistical reproducibility, revealed a critical trade-off: while increasing ABF content resulted in a marginal decline in tensile strength, it significantly enhanced flexural performance. The 50:50 ratio was identified as the optimal blend, achieving a mean Flexural Strength and a Modulus of Elasticity of 2,966.40 MPa, which meets and exceeds commercial PVC benchmarks. Structural feasibility was further validated through theoretical modeling of a U-type profile, which yielded a Section Modulus (Z) of 3.33×105 mm³. Albeit serviceability analysis identified a deflection gap against the L/180 limit, the composite is confirmed as a viable material for secondary containment barriers. Environmental analysis indicates that the 50:50 blend diverts approximately 6.35 kg of ABF per meter, offering a high-volume solution for plastic waste reduction in civil engineering applications.

Abstract: The use of Recycled Coarse Aggregate (RCA) in concrete has gained attention due to its sustainability benefits; however, its impact on carbonation depth (CD) and the potential for corrosion of steel reinforcement remains a concern. RCA’s increased porosity and water absorption can make concrete more susceptible to carbonation, which accelerates corrosion. This study aims to evaluate the effect of RCA on carbonation depth and compressive strength in concrete exposed to varying carbon dioxide (CO₂) concentrations (1%, 5.5%, and 10%) and carbonation periods (28, 56, and 84 days). Concrete mixes with 0%, 25%, and 50% RCA replacement were prepared with a 1:1.23:2.17 cement-to-sand-to-aggregate ratio and a 0.44 water-cement ratio. The results of the compressive strength tests showed that the control mix (0% RCA) had the highest strength at 25.231 MPa, while the 25% and 50% RCA mixes showed reduced compressive strengths of 22.721 MPa and 22.441 MPa, respectively. For carbonation depth, higher RCA content, CO₂ concentration, and longer exposure times resulted in deeper carbonation. The deepest carbonation depth of 13.54 mm was observed in the 50% RCA mix exposed to 10% CO₂ for 84 days. The Response Surface Methodology (RSM) model developed to predict carbonation depth showed a good fit, with an Adjusted R² of 79.98% and a Predicted R² of 74.83%, indicating reliable predictive capabilities. This study highlights the importance of managing RCA content and environmental conditions to optimize concrete durability.

Abstract: Corrosion is one of the factors that affects a material's workability, particularly when water is present. In this study, integral waterproofing admixtures were incorporated into reinforced concrete to reduce the rate of corrosion in steel bars. The study looks at the relationship between different percentages of waterproofing admixture, reinforced concrete workability, compressive strength, reinforcement corrosion level, water permeability, and crack width. These parameters aided in determining the effectiveness of the waterproofing admixture. The methodology for the study includes a variety of tests, including slump test, compressive strength test, impressed voltage test, and rapid chloride permeability test. All concrete samples with waterproofing passed slump tests, with compressive strengths ranging from 24-29 MPa, meeting or exceeding the target strength of 28 MPa. Chloride ion penetration exhibited a nonlinear trend, with reduced penetration observed at the highest and lowest admixture levels, most likely due to increased compaction. Corrosion resistance improved with increasing admixture levels, as samples with the highest percentages lost the least mass. The waterproofing addition also prevented cracking, which increased the concrete lifespan and reduced maintenance expenses. Linear regression indicated that increasing waterproofing content improves compressive strength, reduces water permeability, and enhances overall performance, making it sustainable and resilient.