Development and mechanical evaluation of interlocking block incorporating eggshell powder and recycled concrete aggregate

In response to the growing environmental concerns surrounding the depletion of natural resources and the accumulation of construction waste. The increasing demand for sustainable construction materials has driven research into alternative binders and aggregates, such as Eggshell Powder (ESP) and Recycled Concrete Aggregates (RCA), to minimize environmental impact and reduce reliance on natural resources. There is insufficient research on the combined effect of ESP and RCA in interlocking blocks. Although eggshell powder and recycled concrete aggregates show potential impact individually, their combined effect on the reliability of interlocking blocks remains underexplored. This research addresses the challenge of designing eco-friendly masonry units by pursuing three main objectives. First, it aims to determine the salient mix design incorporating ESP and RCA that balances strength and durability requirements. Second, it involves the design and fabrication of interlocking blocks using the selected mixtures, ensuring structural performance and practical applicability. Third, the research evaluates the predictive capability of an Artificial Neural Network (ANN) model trained on experimental data from the first two objectives, enabling accurate estimation of mechanical properties and generalization beyond the tested samples. The research incorporated Ordinary Portland Cement (OPC) and Natural Aggregate (NA) as the main constituents, while ESP and RCA served as sustainable substitutes, together with Silica Fume (SF) and a superplasticiser in a 1:4 mortar mix (w/r = 0.65). Cube and prism specimens were prepared to identify the best mix proportions before applying them to interlocking blocks cured for 3, 7, 28, and 56 days. Three block configurations SIB, SICIB, and DTIIB were designed and assessed. Experimental procedures covered particle size distribution, flowability, water absorption, compression, and flexural performance, with the final blocks measuring 280 mm x 125 mm x 100 mm and cured for 7, 14, and 28 days. Based JKR Standards, compressive strength (28 days) is 34.69 MPa (Control), and flexural strength (28 days) of SIB is 4.623 N/mm2 (5EPRCA0), and 5.162 N/mm2 (5EPRCA30) were exceed minimum required strength as reliable baseline. Results of compression strength of cubes, flexural strength of prisms, and flexural strength of interlocking blocks were used to evaluate the experimental results by using ANN. ANN in MATLAB are used to evaluate experimental data of flexural strength, providing a cost-effective alternative to physical testing that potentially achieved the third objective of evaluating the experiment results. This approach accelerates the evaluation process and supports largescale implementation. The 5EPERCA30 mix yielded the best mechanical performance in sustainable interlocking blocks, validated by ANN (R = 0.99701). The SICIB design proved structurally viable, confirming the potential of eggshell powder and recycled aggregates in eco-friendly construction. It promotes green building practices, contributing to sustainable construction and responsible resource management, paving the way for more environmentally friendly infrastructure development.