Recycling of marble dust as paste replacement for improving strength, microstructure and eco-friendliness of mortar

Abstract

Marble waste is generated in a fairly large quantity in the world and has been causing serious environmental problems. Usually, the marble waste is reutilized as cement replacement or aggregate replacement in concrete production. But these two methods of utilization have some drawbacks. In this study, an alternative method, called the paste replacement method, in which marble dust (MD) is added to replace an equal volume of paste without changing the mix proportions of the paste, was proposed, and a number of mortar mixes with different amounts of MD added as either paste replacement or cement replacement were produced for testing of workability, compressive strength and microstructure. It was found that the addition of MD as paste replacement would improve the strength and microstructure of the concrete produced. More importantly, the paste replacement method is better than the cement replacement method in cement content reduction and waste utilization, leading to greater reductions in the carbon footprint (which is mainly from the cement content) and the amount of waste to be disposed.