Use of marble dust containing filler mixture in composite slab production: Relationship between roasting conditions and physical properties of the slab

Abstract

Marble dust generated during slab cutting as reject causes significant environmental problems due to increased reactive surface area. It has closer size distribution with micronized quartz filler used in composite slab. Owing to its high hardness, micronized quartz production is an energy intensive process. This study was conducted to investigate the applicability of marble dust in composite slab production together with micronized quartz as filler. The filler mixture was roasted to mitigate drawback arising from low hardness of marble dust. XRD characterization revealed that phases in roasted filler were wollastonite, larnite, calcio olivine, quicklime and free quartz depending on the roasting temperature and time. Physical tests were applied to clarify the effect of sinter phases on slab properties. Physical properties were determined to retrogress as the roasting temperature increased to 1100°C possibly due to rate of free lime in roasted filler, and then improved again reaching peak point at 1200°C. They ameliorated by increasing roasting time at 1200°C. Larnite and quartz were determined to be effective on improved physical properties than wollastonite and calcio olivine.