Thermal behaviour of PPC and OPC-53 when exposed to extreme temperatures

Abstract

Portland pozzolana cement (PPC) and ordinary Portland cement (OPC) OPC-53 grades of cement are commonly used in India. The thermal responses of these types of Portland cement (PC) differed upon analysing the compressive strengths of their hydrated cement block specimens at elevated temperatures. At 800°C, PPC was able to maintain the integrity of the cube, while OPC-53 failed to do so at 500°C. Thermal analyses were performed to interpret the performance of these two types of PC, and four critical regions of interest, – namely, 100°C, 400°C, 500°C and 800°C – were selected. X-ray diffraction and carbon hydrogen nitrogen sulfur-oxygen elemental analysis were conducted on both cements, and variations in the elemental and phase percentages were observed. The number of pores in OPC-53 was 4·51 times greater than that in PPC at 800°C. Additionally, relatively small pore radii ranging from 2·54 μm to 34·80 μm were observed for OPC-53 at 400°C; however, PPC contained pores with radii ranging from 2·54 μm to 67·23 μm. Ultimately, the development of micropores constitutes one of the primary reasons for structural collapse.