Influence of Alccofine on interfacial transition zone of recycled aggregates in concrete

There is a huge demand for aggregates in the concrete industry and consequently; their alternatives have to be identified to replace the conventional ones. This paper presents a comprehensive study of designed concrete mix with its microstructural analysis focusing on the materials’ impact on interfacial transition zone (ITZ). Recycled concrete aggregates were acquired to replace the natural aggregates. Mixture designs were developed with and without recycled aggregates for M20 and M30 grades of concrete. Mineral supplement, Alccofine has been added at 12% and 15% replacement with cement to enhance the strength and microstructure of concrete. Experimental analysis comprising of mechanical, and durability tests were performed, and compared. Microstructural analysis comprising of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) was performed to study the ITZ of the concrete samples. The inclusion of recycled aggregates did not adhere to much strength enhancement, but their combination with Alccofine has raised the compressive strengths. It is observed that the presence of Alccofine in the concrete design has made it less porous, denser in microstructure, and has achieved rapid strength. The microstructural analysis demonstrates a strong relationship between the thickness of ITZ and cement hydration within the samples of Alccofine.