Investigation of properties of lightweight concrete with calcined diatomite aggregate

This paper reports the investigation of the properties of Lightweight Concrete (LWC) made from Portland cement and diatomite aggregate. The chemical and physical properties of diatomite and the mechanical properties of LWC with regard to the effects of calcined temperature and gradation were studied. The uncalcined diatomite was crushed and calcined at 400, 600, and 800°C for 4 hours and used as lightweight aggregate. A constant Water to Cement ratio (W/C) of 2.0 and Aggregate to Cement ratio (A/C) of 1.6 were used for all mixes. The 28-day compressive strength of LWC of 6.4–11.9 MPa, porosity and water absorption of 34.0–49.4%, modulus of elasticity of 2.0–4.3 GPa, thermal conductivity of 0.166–0.192 W/mK, and unit weight of 1170–1300 kg/m3 were obtained. The results indicated that the strength of concrete increased when the calcined temperature of diatomite and the amount of small-size aggregate were increased. The increase in temperature ridded the burnable elements and improved the properties of diatomite. The small-size aggregate produced good matrix-aggregate bonding and enhanced the strength of concrete. The calcined diatomite could, therefore, be used as good aggregate in making lightweight concrete.