An experimental approach to a cementitious lightweight composite mortar using synthetic wollastonite

Abstract

Synthetic wollastonite (SW) has been produced with a special green route being made up of three steps by using industrial marble and quartz wastes. Due to the acicular and fibrous shape, SW has been tried to improve engineering characteristics of cementitious lightweight composite mortar (CLCM). In this experimental study, ecofriendly CLCM was developed with SW as a cement replacement material. Physical and chemical properties of SW were specified with XRF, XRD and SEM analysis. The cement replacement levels were evaluated as 0, 0.5, 1, 2, 5, 10 and 20 %. Setting time, normal consistency, and mineralogical investigation with XRD analysis were investigated on cementitious pastes. Flowability, unit weight, water absorption, flexural and compressive strength, ultrasonic pulse velocity (UPV), and thermal conductivity analysis were carried out on CLCMs. Morphological observations reveal that SW grains were quite finer than cement particles, fibrous and acicular in shape, have a high aspect ratio, and have rough surfaces. Depending on the physical properties of SW, the water requirement of the cementitious paste increased and the setting times were delayed. Similarly, the workability of CLCMs decreased slightly, but a significant improvement was observed in the mechanical properties of the mortars at 2 % and 5 % replacement levels. Also, thermal conductivity of the mortars decreased as the SW replacement level increased. This research verifies the technical feasibility of SW application as a cement replacement in CLCM and may further promote the utilization of waste materials in production of SW.