Mechanical properties, nanoscale characteristics, and environmental analysis of high-volume waste coral powder mortar (HVCM)

Abstract

With the development of marine resources, coral-based cement compositions have broad application prospects in coastal infrastructure construction such as island reef construction, flood control embankment, airport, and road, etc. Waste coral powder (CP) was used to prepare high-volume CP mortar (HVCM), and its multiscale characteristics and environmental benefits were assessed, such as strength, microstructure, and nanoscale characteristics. The results showed that with the increase of CP substitution level, the mechanical properties of HVCM decreased, and the autogenous shrinkage of the mixture was significantly improved. The use of CP to replace the high-volume cement degraded the microstructure of the samples. From the perspective of nanoscale characteristics, the incorporation of CP reduced the content of hydration phase in the matrix and increased the pore phase. Meanwhile, the widening of the interfacial transition zone of the HVCM samples was also the main reason for their performance degradation. Although the incorporation of CP decreased the average elastic modulus of C-S-H and increased its total porosity, the pore structure of the gel was slightly refined. In addition, HVCM had lower carbon emissions and consumption of non-renewable energy compared to plain mortar.