Re-use of waste marble dust in the production of cement and concrete

The main objective of this research is to investigate the possibility of utilizing waste marble dust (MD) in cement and concrete production. The research work was divided into two sections. The first section deals with the properties of cement modified with marble dust (marble dust blended cement), whereas the second section discusses the properties of concrete contained marble dust as a cement replacement and as a sand replacement (cement addition). The replacement ratios which have been studied were 0.0%, 5.0%, 7.5%, 10.0% and 15% by weight. Water to powder ratio (w/p) or water to cement ratio (w/c) were 0.50 and 0.40 in case of cement replacement and in case of sand replacement respectively. Physical, mechanical and chemical properties of cement and concrete modified with marble dust were investigated. In addition, TGA, XRD and SEM analysis were performed. Test results of cement paste and cement mortar indicate that the marble dust blended cement remains within the acceptable ranges of the Egyptian standards. Also, generally, the use of marble dust in concrete production as cement replacement or as sand replacement (cement addition) gradually enhances both of the mechanical and physical properties of concrete especially with lower w/c ratio. Marble dust showed a filler effect in concrete and had no noticeable role in the hydration process. Yet, concrete made with marble dust as sand replacement achieved better performance compared to concrete made with marble dust as cement replacement.