Synergizing Portland Cement, high-volume fly ash and calcined calcium carbonate in producing self-compacting concrete: A comprehensive investigation of rheological, mechanical, and microstructural properties

The manufacturing of Ordinary Portland Cement (OPC) is one of the primary contributors to atmospheric CO 2 . The use of high-volume OPC replacement materials in self-compacting concrete (SCC) has been the focus of several investigations owing to the increased demand for environmentally friendly building materials. This paper presents the experimental investigation of the properties of SCC, where 25-70% OPC was replaced with fly ash and calcined calcium carbonate (BCC). Different experimental tests, such as workability, mechanical properties, durability, and microstructural characteristics, have been carried out. The test results of workability showed that all the mixes were conforming to satisfactory conditions of EFNARC for the T500 flow timings within the range from 2.50 to 4.55 seconds and slump flow values within the range from 650 to 800 mm. This mix, here called 20F5C, had optimum behavior with its 91-day compressive strength of 73.8 MPa, a gain of 7.7% over the control. Replacement ratio, microstructure, and mechanical properties were correlated. Even high-replacement mixes like 50F20C provided a 91-day compressive strength of 58.9 MPa. This clearly shows the prospect of a considerable reduction in cement consumption while maintaining structural integrity. These results indicate the possibility of reduced OPC consumption in concrete production, which again identifies low carbon emission and utilization of waste according to international sustainability goals. The findings have revealed that SCC made with high-volume replacements of OPC could be an economically viable and environmentally friendly solution for the construction industry worldwide.