Pressed lightweight concrete containing calcined diatomite aggregate

Diatomite in its natural form possesses low reactivity and is a weak material. Calcination rids of the burnable elements and enhances the properties of diatomite. This research studies the properties of pressed lightweight concrete containing calcined diatomite aggregate. The diatomite was crushed and classified as fine, medium and coarse aggregates and then calcined at 400-1000 °C for 4 h. The pressed lightweight concretes with 28-day compressive strength of 7.8-12.9 MPa, density of 1000-1200 kg/m3, porosity of 58-61%, water absorption of 61-72% and thermal conductivity of 0.15-0.19 W/mK were obtained. The light weight and high strength blocks were obtained with the use coarse diatomite aggregate obtained from high calcined temperature of 1000 °C and the use of fine diatomite aggregate obtained from calcination temperature of 600 °C. At the high temperature of 1000 °C, the coarse aggregate was stable and strong and this contributed to the strength of the pressed lightweight concrete. At the calcination temperature of 600 °C, the fine diatiomite aggregate was reactive. Calcined diatomite is a suitable lightweight aggregate for making pressed lightweight concrete blocks.