RSM-based modelling for predicting and optimizing the rheological and mechanical properties of fibre-reinforced laterized self-compacting concrete.

A sustainable method to reduce the use of natural resources and the negative effects of the concrete industry on the environment is to use waste lateritic aggregate in self-compacting concrete and evaluate its fresh, mechanical and durability characteristics. Using RSM's central composite design (CCD), Thirteen different SCC mixtures have been designed with varying input factor combinations (LA: 0-100%, PPF: 0-2%) and tested for eight responses (rheological properties, like slump flow, V-funnel time, and T500; mechanical properties, like compressive, split-tensile, and flexural strengths, and durability properties like drying shrinkage and rapid chloride penetration test). The analysis of variance (ANOVA) test was performed to determine the accuracy of the mathematical models developed following the experimental results. ANOVA was used to verify eight response models (seven quadratic and one linear). The inclusion of laterite aggregate has been found to linearly reduce the workability of fresh concrete. Self-compacting concrete will have a lower V-funnel value if any combination of components falls below these two limit values (31% LA and 1.12% PPF). The area bounded by the 760-mm contour line and the graph axes recorded the highest slump flow at (28% LA and 1.26% PPF). Similarly, SCC with a lower T500 value will be produced by any combination of components below these two limit values (25% LA and 1.11% PPF). By replacing 28.5% of the granite aggregate with laterite aggregate and adding 1.24% polypropylene fiber, the compressive strength of M30 grade self-compacting concrete increased by 12.33% after 28 days. A similar strength gain of 7.89% was seen in the splitting tensile by replacing 28% of the granite aggregate with laterite aggregate and adding 1.46% polypropylene fiber over the control mix, and a flexural strength gain of 14.46% was seen by replacing 31.4% of laterite aggregate and adding 1.2% polypropylene fiber, respectively. The low drying shrinkage values are related to a combination of LA concentration (34.4% replacement) and PPF (1.31%) and minimum chloride ingress is located in the region with a LA concentration (30.5% replacement) and a PPF content (1.26%), The projected optimal data were verified experimentally with an error rate of less than 5%. Thus, it is highly recommended that the created model be adequate and capable of optimizing both the experimental and analytical values. It is recommended that the utilization of 25% LA and 1% PPF in lateritic self-compacting concrete provides optimum outcomes for the construction industry in the field of civil engineering.