Mechanical, environmental and economic performance of structural concrete containing silica fume and marble industry waste powder

Abstract

Marble waste powder (MWP) is an inert material that is obtained as an industrial by-product during sawing, shaping, and polishing of marble and causes serious environmental problems. This paper describes the procedures and results of a laboratory investigation of mechanical properties carried out on 16 concrete mixes containing MWP and silica fume (SF) as partial replacement of ordinary Portland cement (OPC). OPC was partially replaced at different ratios of SF (0%, 2.5%, 5%, 10%) and MWP (0%, 5%, 10%, 20%). In all concrete mixes, constant water/binder ratio of 0.45 and target initial slump of S2 class (50–90 mm) were used. Workability and bulk density tests were carried out on fresh concrete, while compressive strength, splitting tensile strength and modulus of elasticity tests were performed to evaluate some relevant properties of concrete in the hardened state. Eventually, all of the concrete mixes were evaluated in terms of economic, environmental and mechanical approaches.It was found that the mechanical properties of concrete containing MWP tend to decline for replacement ratios over 10% but satisfactory results were obtained below that level. Regarding the use of SF, it was observed that it improves the mechanical performance of concrete with MWP by offsetting the decline of its properties relative to conventional concrete. The comparison of the concrete mixes in terms of different approaches has shown that the optimized mix occurs when MWP and SF are used simultaneously. The proper use of MWP as a replacement for cement would have environmental benefits and boost the viability of the marble stone industry.