This study evaluates the feasibility and performance of concrete blended with industrial and agricultural wastes, using fly ash and coconut shell, reinforced with hybrid fibers. Researchers are increasingly turning to sustainable alternatives to traditional construction materials, drawn by the necessity to address depletion issues and effective waste management.
Concrete is fundamental to modern construction, but its primary ingredient, Portland cement, is energy-intensive to produce and contributes significantly to greenhouse gas emissions. Concurrently, industrial and agricultural waste such as fly ash (FA) and coconut shells present potential alternatives. FA is obtained from the combustion of coal, particularly from thermal power plants, and can serve as a supplementary cementitious material (SCM). Coconut shells, often considered waste and discarded, offer unique properties as aggregates, which support innovation and sustainability.
The present study, led by researchers from India, is structured around four distinct phases. An initial reference mix was created using conventional materials. Subsequently, up to 30% of the cement was replaced with FA, which research indicates enhances the strength and durability of concrete. Notably, replacing natural coarse aggregates (NCA) with coconut shell aggregates (CSA) was explored, contributing to significant cost savings and resource efficiency.
The culmination of this study centered on hybrid fiber reinforcement, combining steel and polypropylene fibers. Results indicated substantial increases in mechanical properties: substituting 1% steel fiber (SF) resulted in increases of 11.9%, 33.0%, and 30.7% respectively for compressive, split tensile, and flexural strengths. Including 0.2% polypropylene fibers (PPF) yielded additional enhancements, amplifying these strengths and improving ductility.
Using advanced statistical methods such as artificial neural networks and response surface modeling, the research established predictive capabilities for the compressive strength of hybrid fiber reinforced coconut shell aggregate concrete (HFRCSAC). According to the authors, "The ANN models are used to predict the compressive strength with good accuracy."
Through rigorous testing, the findings showed 20% FA replacement improved compressive strength, split tensile strength, and flexural strength by 8.1%, 5.9%, and 7.8%, respectively. Conversely, adding greater amounts of CSA indicated diminishing returns on mechanical performance. Yet, the experimentation concluded, "The addition of 1% SF to CSAC improved the hardened properties..."
By leveraging local industrial and agricultural wastes, the study not only contributes to sustainability within the construction sector but also enhances the mechanical performance of concrete through innovative practices. These findings indicate the potential application of HFRCSAC, promoting both economic and environmental sustainability, and urge the industry to re-evaluate standard practices toward a more eco-friendly construction paradigm. Future studies should focus on optimizing hybrid fiber dosages, enhancing the sustainability of concrete, and determining the long-term durability of these alternative materials.