Construction Practices Research Articles

Microstructural analysis and prediction of strength response of black expansive soil

Amelioration studies using waste residues are gaining popularity in the construction sector, as they offer dual effective management and utilization of waste residue. This practice is of interest to the growth of any nation due to environmental protection and the economic advantages it offers. For that reason, this present-day study seeks the sustainable utilization of calcium carbide residue (CCR) and palm oil fuel residue (POFR) in expansive soil amelioration. After an in-depth characterization of the parent soil, several number of California bearing ratio (CBR) tests was performed on the parent and additive-treated soil. For this purpose, a total of twenty mixes were prepared possessing various combinations of CCR, POFR, water, and soil. CBR testing for soaked and unsoaked conditions was carried out to assess the strength performance and effectiveness of the additives. Through this approach, optimal California bearing ratio (CBR) values of 41 and 61% were achieved at trial runs designated Y4 for soaked and unsoaked conditions, indicating a strong mechanical performance. These experimental outcomes were subsequently validated using statistical indicators such as ANOVA (F crit > F) and student t-test (t crit > t stat). A step further, microstructural testing such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) were performed on the natural soil and soil treated with the optimal level of additives obtained at trial runs designated Y4. The SEM micrographs evidence the transformation of the loosely packed structure of untreated soil into a dense soil composite. Similarly, diverging molecular functional groups were recorded in the FTIR examination with the incorporation of blended CCR-POFR. Finally, the findings suggest that carefully designed mixtures of CCR and POFR can offer a sustainable, efficient approach to soil amelioration, potentially revolutionizing construction practices.

Seismic Upgrading of the Heritage-Protected Reinforced Concrete Warehouse in Rijeka, Croatia

Despite Croatia experiencing two strong earthquakes in 2020, Rijeka was not directly affected, underscoring the importance of proactive seismic assessment and strengthening in all seismic regions. This paper presents a comprehensive case study on the seismic strengthening of a 20th-century concrete building located in Rijeka, Croatia, originally designed according to Austro-Hungarian construction norms and practices. As a heritage-protected structure, the building’s architectural features and construction practices were examined and contextualized within its historical background. The assessment and renovation phases of this project are discussed in detail, demonstrating the practical application of modern seismic strengthening techniques while preserving the building’s historical integrity. This case study aims to highlight the need for such measures to protect heritage structures and to show the implementation of rapid and new (ad hoc) norms for earthquake-damaged buildings in Croatia. This study serves as a reference for engineers, architects, and conservationists involved in the preservation of heritage buildings, demonstrating that it is possible to enhance their structural safety without compromising their architectural authenticity.

Hybrid simulation testing of two-storey low-aspect-ratio nuclear RC shear walls with normal- and high-strength reinforcement: Seismic performance evaluation and economic assessment

Low-aspect-ratio reinforced concrete (RC) shear walls have been commonly used in several nuclear facilities in containment and safety-related structures. Despite being a potential alternative to reduce rebar congestion and subsequently minimize complex construction activities typically associated with nuclear facilities, there has been limited experimental research on investigating the impact of using high-strength reinforcement (HSR) on the seismic performance of such walls, particularly in a multi-storey context. This lack of research is mainly due to considerable challenges imposed when testing such multi-storey nuclear RC shear walls in most laboratories. Therefore, the current study presents the experimental results of two two-storey low-aspect-ratio nuclear RC shear walls that were tested utilizing the seismic hybrid simulation testing technique. In this respect, walls W1-NSR and W2-HSR were designed using normal-strength reinforcement (NSR) and HSR, respectively, where the two test walls had comparable capacities to allow for direct comparisons. Both walls were subjected to various ground motion levels, spanning from operational to design and beyond-design earthquake scenarios. The experimental findings are then presented to include the force-displacement responses, the multi-storey effects, ductility capacities, lateral and rotational stiffnesses, rebar strains, and cracking patterns of the test walls. Subsequently, an economic assessment was carried out to quantify the total rebar weights and the corresponding construction costs of such walls. In addition, the expected seismic repair costs were determined based on a three-dimensional digital image correlation technique that provided information on the damage states of the test walls under different earthquake levels. The results show that although W1-NSR and W2-HSR attained similar force and moment capacities, W2-HSR achieved a relatively higher ductility capacity than W1-NSR. However, larger cracks were observed in W2-HSR compared to W1-NSR, which was attributed to the associated larger rebar spacing in the former relative to the latter. The economic assessment results demonstrate that using HSR minimized the rebar weights and construction costs, while both walls had similar seismic repair costs at their design and beyond-design earthquake levels. Both the seismic performance and economic assessment results presented in the current study are expected to aid future editions of relevant design standards in adopting HSR in nuclear construction practice.

Eco-Sustainable Cement: Natural Volcanic Tuffs’ Impact on Concrete Strength and Durability

This study underscores the potential of utilizing natural volcanic tuffs (NVTs) as supplementary cementitious materials (SCMs) in alignment with global sustainability efforts aimed at mitigating the cement industry’s negative impacts on both the economy and the environment. Experimental investigations were conducted on concrete mixtures containing 10%, 20%, 30%, 40%, and 50% NVT as partial cement replacements to assess their influence on concrete’s mechanical and microstructural properties. Based on the findings, concrete samples with 10% NVT replacements exhibited increased flexural and compressive strengths of 35.6% and 5.6%, respectively, compared with ordinary concrete after 28 days. The depth of water penetration in the concrete samples was significantly reduced by the inclusion of NVT, with a maximum reduction of 56.5%. Microstructural analysis using scanning electron microscopy (SEM) revealed enhanced densification of the concrete microstructures, attributed to the high pozzolanic activity of NVT use in cement-based composites. Analysis of variance (ANOVA) revealed statistically significant relationships between NVT content and both the compressive and flexural strengths of the concrete samples. In conclusion, substituting 10% cement with NVT not only enhances the mechanical properties of concrete but also decreases the energy demand for cement production and reduces carbon dioxide (CO2) emissions, thus contributing to more sustainable construction practices.

Hybrid XGB model for predicting unconfined compressive strength of solid waste-cement-stabilized cohesive soil

The utilization of cement has been found to have negative environmental impacts. In order to reduce the quantity of cement used and improve the mechanical properties of solid waste-cement-stabilized cohesive soil, the incorporation of solid waste as additives has been investigated. Unconfined compressive strength is a crucial parameter in geotechnical engineering. However, existing empirical formulas have limited accuracy and applicability when it comes to the unconfined compressive strength of solid waste-cement-stabilized cohesive soil. The machine learning model can be used to provide accurate and comprehensive predictions by considering the nonlinear relationships between independent and dependent variables. This study aims to propose a machine learning model tuned by optimization algorithms with high generalization performance in accurately predicting the unconfined compressive strength. Firstly, a database containing 474 specimens was developed. Secondly, eight machine learning models were established, composed five single models and three hybrid models, to train and test the database. Six performance indicators were employed to evaluate the generalization ability of these models. Finally, the optimal model was selected for analysis of the importance of the feature variables using shapley additive explanations, which were compared with those of the existing empirical model. The research findings indicated that, the extreme gradient boosting model tuned with tree-structured parzen estimators exhibited the highest predictive accuracy and generalization ability. The curing age, cement content, plastic limit, and water content were identified as the most critical factors influencing the unconfined compressive strength. Among the chemical components in solid waste, the aluminum oxide content and silicon dioxide content were found to significantly influence the unconfined compressive strength, while the impact of calcium oxide content was relatively minor. Furthermore, the optimal solid waste content was found to be around 10 %. This study made a significant contribution to the effective utilization of waste resources in the context of sustainable construction practices.

Effects of elevated temperature and treatment duration on selected index and engineering properties of lateritic soils

Lateritic soils are important to various engineering applications, especially in tropical regions, where they serve as key components in road construction, embankments, and other geotechnical structures. This study investigated the combined effects of elevated temperature and heating duration on the index and engineering properties of lateritic soils derived from two distinct parent rocks (charnockite and quartzite) in Ado-Ekiti, Nigeria. Disturbed lateritic soil samples were heated in a furnace at various temperatures (100, 200, 300, and 400 °C) for two designated durations (2 and 3 h). Standard geotechnical tests were conducted to evaluate Atterberg limits, compaction parameters, and unconfined compressive strength. The results showed that elevated temperature led to a decrease in the plastic limit, liquid limit, plasticity index, optimum moisture content (OMC), and UCS for both soils, though the extent varied between the two parent rocks. For instance, at 400 °C for 3 h, the plasticity index decreased by 47.82% for charnockite-derived soil and 55.22% for quartzite-derived soil. At the same temperature for 2 h, it decreased by 38.79% for charnockite-derived soil and 48.92% for quartzite-derived soil. Similarly, UCS decreased by 29.83% for charnockite-derived soil and 25.97% for quartzite-derived soil at 400 °C for 3 h, while at 400 °C for 2 h, UCS decreased by 21.20% for charnockite-derived soil and 23.48% for quartzite-derived soil. Conversely, maximum dry density (MDD) increased with temperature, rising by up to 20.64% for charnockite-derived soil and 14.66% for quartzite-derived soil at 400 °C for 3 h, and by 18.29% for charnockite-derived soil and 12.62% for quartzite-derived soil at 400 °C for 2 h. Longer heating durations (3 h) generally caused more pronounced changes in soil properties compared to shorter durations (2 h). For instance, OMC decreased by 13.41% for charnockite and 14.18% for quartzite at 400 °C for 3 h compared to a 2-h duration. Statistical analyses indicated that temperature had a significant influence on most properties, while the effect of heating duration was less consistent. These findings highlight the need to consider both temperature and heating duration when evaluating the engineering behavior of lateritic soils exposed to elevated temperatures. Practical implications include potential adjustments in construction practices and design parameters for road construction and embankments in regions prone to high temperatures, such as those experiencing frequent forest fires.

Effect of plantain peel ash as an admixture on concrete properties

This study investigates the effect of plantain peel ash as an admixture on concrete properties, which is a sustainable alternative to conventional concrete production. The aim is to optimize the mix design of concrete required for improved performance, investigate the effect of the plantain peel ash on the compressive strength of the concrete, and examine the effects of plantain peel ash as a supplementary material on the durability and service life of concrete. The use of plantain peel ash as an admixture for cement in concrete has gained increasing popularity due to its ability to reduce the environmental impact of concrete production. This study contributes to the understanding of the durability and performance of plantain peel ash in concrete which is crucial for sustainable construction practices. The methodology involves mix design according to IS 10262:2009 for M15 grade of concrete with 5%, 10%, 15% and 20% plantain peel ash replacement, testing of compressive strength and durability of the concrete samples and also the optimal dosage required, in comparison with conventional concrete. The result of this study shows that the addition of 5% plantain peel ash increases the compressive strength of the concrete with obtained value of 27.30 N/mm2 and also has the standard workability for a normal concrete at 45 mm for the control and 60 mm for 5% PPA. The 10%, 15% and 20% shows a decrease in their compressive strength compared to the control mix (0%) with a value of 18.42 N/mm2 for 28 days curing. Overall, it can be said that 5% plantain peel ash has provided a strong basis for the use of plantain peel ash in concrete mixtures. The 5% is equivalent to 0.72 kg PPA.

Exploration and Practice of Course Ideology and Politics Construction in Engineering Course of Application-oriented Universities

This paper analyzes the problems in the construction of course ideology and politics, uses information technology to enable the change of thinking mode, and explores the innovation research on the new carrier and new model. The concept of tree in computer science and technology is applied to the construction of course ideology and politics, based on that a standardized ideological and political case base is built and a closed-loop model is proposed. Through the integration design of the core value system and the entire process of education and teaching, the integrated development of professional construction and ideological and political education is realized.

A Perception Survey of Lean Management Practices for Safer Off-Site Construction

Lean practice is recognised for having a great potential in promoting safety risk management in off-site construction (OSC). This paper presents results of a study conducted to assess the impact of lean practice on safety risk management in OSC in a developing country. A quantitative approach using a survey-based questionnaire was adopted. Lean management practices (LMPs) identified from a literature review were empirically tested using a sample survey of 103 OSC contractors. The survey responses were subjected to descriptive and inferential statistics. The top ranked LMPs for safety risk management in OSC included two mistake-proofing practices, i.e., use of personal protective equipment (PPE) and use of hazard warning equipment; two last planner system (LPS) practices, i.e., involvement of workers in safety planning and providing necessary working equipment; and one first run studies (FRS) practice, i.e., critical analysis of work methods. These LMPs are useful in controlling high-consequence safety risks in OSC. Based on evidence found in this study, the paper argues that lean practice can bring great value to safety risk management in OSC in countries where OSC is transitioning.

Spatial spillover effects and correlation network analysis of green construction development efficiency in China

Green construction has been implemented globally to address resource depletion and environmental degradation. The effectiveness of green construction development depends on the efficiency of resource utilization and the common progress of all regions. However, existing studies have paid limited attention to green construction development efficiency (GCDE) and its spatial correlation. This study uses the super-efficiency slacks-based measure (Super-SBM) model, spatial econometric models, and social network analysis (SNA) method to reveal the spatial distribution, spatial spillover effects, and spatial correlation of GCDE across 30 provinces in China. The results indicate significant disparities in GCDE among regions, with the eastern region exhibiting considerably higher GCDE than the western and northeastern regions. There is evidence of spatial spillover effects, and the spatial correlation of GCDE is strengthening. Provinces with high GCDE occupy central positions in the GCDE network and exert spillover effects on other provinces, while underdeveloped provinces have opportunities to benefit from regional cooperation. The findings provide policy insights for the implementation and enhancement of green construction development actions. Moreover, they provide Chinese experience for green construction practices in other areas of the world.

EXAMINING THE USE OF MARBLE WASTE AS A SUBSTITUTE OF CONVENTIONAL MATERIALS IN CONCRETE: A BRIEF REVIEW

For decades studies have investigated using marble waste as a partial replacement for conventional materials in concrete. This review examines the findings on substituting marble waste for coarse aggregate, fine aggregate, and cement. The studies accessed suggest that replacing up to 50% of coarse aggregate with marble waste can improve the concrete's mechanical properties and durability. Using marble waste for up to 20% of fine aggregate in concrete, mortars, and self-compacting concrete improves workability, compressive strength, and sustainability. Additionally, substituting up to 10% of cement with marble dust helps reduce cement consumption and the environmental impact of concrete production. The benefits of using marble waste include better mechanical properties, cost savings, and a smaller ecological footprint. Despite the numerous benefits, gaps in research persist, particularly in long-term performance studies, standardized testing methods, and comprehensive life cycle assessments. This review highlights the potential of marble waste as a valuable resource in the concrete industry and underscores the need for further research to optimize its use and fully realize its benefits in sustainable construction practices.

Delays Factors for Construction Projects in South of Iraq

This study seeks to identify and categorize the factors responsible for delays in construction projects in southern Iraq. Using a sequential research approach that includes a literature review, interviews, and surveys, data were collected from 115 industry professionals, including clients, consultants, project managers, contractors, and engineers. The analysis utilized both descriptive and conclusive statistical methods, with a specific emphasis on the Spearman rank correlation coefficient to verify the reliability of the delay factor rankings. The research identified 45 major delay factors, with the most critical being global and local economic crises, bureaucracy and corruption, public holidays, delays in securing municipal permits, and frequent change orders initiated by clients. These factors were further classified into eight categories: inaccuracies in the tendering process, technical performance management, government interference, rework in construction practices, among others. The results indicate strong consensus among the different respondent groups regarding the main causes of project delays, as demonstrated by high correlation coefficients and a Chi-squared test confirming the agreement's significance. The findings provide valuable insights for practical applications and academic research, supporting the selection of project leaders, anticipating potential delays, and improving project management practices in Iraq. The study suggests future research should focus on strategic economic planning, exploring alternative funding sources, combating corruption, and implementing regulatory reforms to address the identified delay factors.

Experimental and Statistical Analysis of Concrete Eco-Cobble Using Organic and Synthetic Fibers

The environmental impact of traditional construction materials necessitates the development of sustainable alternatives. This study evaluates eco-cobbles as novel building materials designed to reduce environmental footprint while maintaining performance standards. The objectives were to develop an eco-friendly cobble alternative and assess its effectiveness through laboratory tests. Eco-cobbles were synthesized using recycled and bio-based materials and tested for compressive strength, flexural strength, and water absorption at 14 and 28 days. The compressive strength ranged from 11.5 MPa to 26.8 MPa, with a maximum value observed at 28 days in a mixture containing 95% concrete and 5% polyethylene terephthalate (PET). Flexural strength varied from 9.1 MPa to 28.7 MPa, with the highest value achieved in a mixture of 95% concrete and 0% fibers. Water absorption rates ranged from 2.1% to 6.6%, demonstrating an effective balance between performance and durability. Environmental assessments indicated a 30% reduction in resource consumption and a 40% decrease in carbon footprint compared to traditional cobble production methods. The findings demonstrate that eco-cobbles not only meet performance standards but also offer significant environmental benefits with a 99% compliance from the results obtained by response surface methodology plots, confirming that eco-cobbles offer a viable, sustainable alternative to conventional materials, with the potential for broader application in eco-friendly construction practices.

New Zero-Carbon Wooden Building Concepts: A Review of Selected Criteria

A Carbon Footprint (CF) is defined as the total emissions of greenhouse gases, primarily carbon dioxide, methane, and nitrous oxide, and is a specific type of Environmental Footprint that measures human impact on the environment. Carbon dioxide emissions are a major contributor to anthropogenic greenhouse gases driving climate change. Wood, as a renewable and ecological material, has relatively low carbon emissions. The study aimed to review and analyze the criteria influencing the feasibility of constructing modern zero-carbon wooden buildings. The review was conducted in two phases: (i) a literature review and (ii) an assessment of existing buildings. The preliminary research led to (i) narrowing the focus to the years 2020–2024 and (ii) identifying key criteria for analysis: sustainable material sourcing, carbon sequestration, energy efficiency, life cycle assessment (LCA), and innovative construction practices. The study’s findings indicate that all these criteria play a vital role in the design and construction of new zero-carbon wooden buildings. They highlight the significant potential of wood as a renewable material in achieving zero-carbon buildings (ZCBs), positioning it as a compelling alternative to traditional construction materials. However, the research also underscores that despite wood’s numerous potential benefits, its implementation in ZCBs faces several challenges, including social, regulatory, and financial barriers.

Comparative study of natural fiber-Reinforced composites for sustainable thermal insulation in construction

Natural fiber-reinforced composites are increasingly recognized as sustainable alternatives in construction materials due to their environmentally friendly properties and ability to increase thermal insulation. This study conducts an in-depth comparative study between palm fiber (DPF) composites and other natural fiber-reinforced composites, including hemp and jute, with a focus on their application as insulation that provides insight into their thermal properties, performance, and mechanical properties to inform sustainable construction practices. The research methodology involves constructing and producing composite samples using date palm, hemp, and jute fibers, each combined into a common base material. Composites are mold-made, ensuring consistent and reproducible samples for testing. Through a systematic investigation, we explore these composites' thermal, and mechanical properties. Testing covers a specific range of fiber loadings, from 10 wt % – 30 wt %. Specific characterization techniques, including compression test, bending test, impact, FT-IR, and DSC, were used to evaluate the behavior of the composites under various conditions. Our results show that the thermal conductivity of the composites ranges from 0.0514 – 0.084 W/m. K for different fiber loading is affected by the fiber content.Furthermore, at maximum fiber concentration (30 by weight), the highest heat capacity of the hemp composite was 1674 J/Kg.K. The 30 wt % of jute and date palm composites achieved a maximum compressive strength of (70 MPa) and (64 MPa) respectively.In summary, this comprehensive study demonstrates the potential of natural fiber-reinforced composites as sustainable and fully bio-based alternatives for construction-related applications. Superior thermal properties and improved mechanical strength highlight their viability in thermal insulation applications.

Experimental investigation of quarry rock dust incorporated fly ash and slag based fiber reinforced geopolymer concrete circular columns

Manufacturing ordinary Portland cement (OPC) poses significant challenges for sustainable construction practices. OPC manufacturing emits substantial greenhouse gases into the atmosphere and demands extensive raw materials. In pursuit of greener alternatives, researchers explore geopolymer concrete (GPC), a revolutionary material that entirely replaces OPC, comprising industrial wastes/by-products activated through an alkaline solution. The study aims to investigate the feasibility of incorporating quarry rock dust (QRD) into GPC production for environmentally sustainable structural applications. Circular columns (200 mm diameter, 1000 mm length) were formulated using GPC blends with fly ash, slag (SG), and QRD as a partial SG replacement. The structural performance of these columns, with and without steel fiber reinforcement, was evaluated under varied loading conditions. Results show that QRD is a valuable ingredient in GPC for structural concrete elements, offering performance comparable to traditional OPC concrete. Furthermore, the incorporation of steel fibers significantly enhances the peak axial loads, displacement response, and overall performance of GPC columns with or without QRD. Fiber-reinforced GPC columns demonstrated approximately 8–10% higher ultimate load capacity than equivalent OPC columns. Eccentricity was found to significantly reduce ductility, but fiber reinforcement offers substantial ductility improvements (25–55%).

Environmental Sustainability of Pile Construction Activities in Nigeria; Strategies and Best Practices

: Pile construction activities is a multifaceted activity among the construction activities that are performed by heavy machines, materials and energy sources generating environmental impacts associated with pilling activities such as carbon emissions, noise, heavy vibration, soil instability and groundwater pollution. Sustainable piling construction guarantees that the whole piling process meets environmental sustainability and ultimately human health and wellbeing. Data were gathered through a questionnaire survey administered to construction professionals including engineers, project managers, surveyors, and builders. Out of the 50 questionnaires distributed, 41 responses were analyzed. The study employed the Relative Importance Index (RII) to rank the effectiveness of various strategies in mitigating environmental impacts. The findings underscore the critical role of introducing low-emission machinery and optimizing operational hours in reducing carbon emissions. Noise management was most effectively achieved through alternative pile installation methods combined with regular equipment maintenance. Maintaining adequate setbacks from structures and employing controlled installation techniques were identified as essential strategies to mitigate vibration. Addressing soil instability was found to rely heavily on thorough site investigations and the implementation of effective ground stabilization techniques and preventing groundwater pollution requires the proper use of drilling fluids and diligent site management. These findings contributed to the development of environmentally sustainable practices in pile construction, emphasizing the importance of comprehensive strategies to mitigate the adverse environmental impacts of such activities in Nigeria.

Development sustainable concrete with high-volume wastes tile ceramic: Role of silica nanoparticles amalgamation

As the global concrete industry shifts towards sustainable practices, there is an increasing focus on mitigating the environmental impacts of ordinary Portland cement (OPC)-based concrete, which is notorious for its significant greenhouse gas emissions, high energy consumption, and substantial demand for natural resources. This urgency is compounded by the growing production of waste tile ceramic materials due to rapid urban development, leading to enhanced research into their recyclability within concrete for improved durability and sustainability. This study explores the development of high-strength concrete utilizing waste tile ceramic aggregates (WTCAs) and waste tile ceramic powder (WTCP) as replacements for natural aggregate and OPC, respectively. To further enhance the concrete's mechanical properties and microstructure, silica nanoparticles derived from waste bottle glass (WBGNPs) were integrated in varying proportions ranging from 2 % to 10 % of the binder content. Optimal results were achieved with a full replacement of natural aggregate by WTCAs, 60 % substitution of OPC by WTCP, and the inclusion of 4 % WBGNPs, which collectively exhibited superior compressive, splitting tensile, and flexural strengths. Microstructural analyses revealed that the addition of WBGNPs improved the hydration process, increased gel density, and reduced porosity. From the obtained numerical results, the coefficient of determination value of 0.92 further confirms the model's predictive strength, demonstrating that the Random Forest algorithm can reliably estimate the compressive strength. The findings indicate that the concrete formulated with WTCP and WBGNPs not only meets diverse construction demands but also significantly contributes to environmental sustainability by reducing impacts on global warming and minimizing landfill usage. This study advocates for the strategic incorporation of WTCP and WBGNPs in concrete applications to promote environmentally sustainable construction practices. It is highly recommended that WTCP be utilized in sustainable binders as a replacement for OPC and natural aggregates to enhance it strength and durable properties, reduce the environmental issues, costs, and the depletion of natural resources.

Feasibility of utilizing recycled coarse aggregates in commercial concrete production

This study addresses a critical gap in circular construction practices by assessing the use of high-quality Recycled Coarse Aggregates (RCA) from end-of-life concrete on an industrial scale. Unlike previous studies, which predominantly relied on theoretical mix designs or laboratory-level experiments, this research focuses on real-world applicability, employing commercially produced RCA and conventional production methods in industrial settings to identify upscaling challenges. Advanced Dry Recovery technology is utilized to produce high-quality RCA for both ready-mix and prefab concrete production. To ensure practical relevance, the research examines three water-to-cement ratios for ready-mix concrete and three strength classes for prefab concrete, all prepared and cast in a commercial setting using standard industrial practices. The results show that by selecting the appropriate application for RCA, there is potential for concrete companies to produce mixes using 100% RCA that meet standard requirements in terms of fresh, mechanical, and durability properties without the need for extra treatments or specific mixing methods, particularly when the water absorption of RCA is less than 4%. Achieving optimal performance requires adjustments in the mix design, specifically by considering the effective water-to-cement ratio. Additionally, the study underscores the impact of the parent concrete's properties on the RCA quality. This research not only demonstrates the feasibility of employing RCA in industrial-scale concrete production along with its associated challenges but also highlights the potential for enhancing circularity in the construction industry through large-scale adoption of RCA, thereby contributing to sustainable and circular construction practices.

Performance enhancement of asphalt mixture through the addition of recycled polymer materials

Enhancing the performance of asphalt binders is essential for ensuring the long-term durability and serviceability of asphalt mixtures, as it can help reduce the frequency of maintenance and repair work, ultimately leading to the development of more sustainable transportation infrastructure. To achieve this goal, this study investigates the effects of incorporating recycled polymer materials, including reclaimed polyvinyl chloride (PVC) and polystyrene (PS) derived from household waste, into hot mix asphalt. The experimental work involved subjecting the polymer-modified asphalt binders to a range of physical tests, such as softening point, penetration, ductility, indirect tensile strength, Marshall stability, and moisture susceptibility, and the results showed that the addition of recycled polymers, with an optimal content of 4%, led to lower penetration values and higher softening point temperatures, indicating improved resistance to temperature changes. Further analysis of the asphalt mixture performance revealed several beneficial outcomes, including a decrease in flow, a boost in the asphalt mixture's resistance to moisture-induced damage, and an improvement in Marshall stability and indirect tensile strength, with the inclusion of 4% recycled polymers yielding increases in Marshall stability of 43.7% and 37.4% for PVC and PS-modified mixes, respectively, and increments in indirect tensile strength of 32.2% and 29.7% for the same mixes. The study concludes that the use of recycled polymers can effectively enhance the performance and durability of asphalt mixtures, contributing to the development of more sustainable asphalt pavement construction practices by utilizing locally available or reused materials, which could lead to the increased knowledge and application of stronger and more weather-resistant asphalt mixes, ultimately promoting the advancement of sustainable transportation infrastructure.