Insulating and fire-resistance performance of calcium aluminate cement based lightweight mortars

The study investigated the effect of two different cement types and expanded vermiculite powder (EVP) utilized as fine aggregate on the insulating and fire-resistance performance of lightweight mortars. To lower the density and heat conductivity of mortars, EVP was utilized as a 'full' replacement for river sand. Cements used were calcium aluminate cement (CAC) and Portland cement (PC). Four different EVP/cement (PC or CAC) ratios were determined: 3, 4, 5 and 6. The mortar specimens produced were exposed to temperatures of 20 degrees C, 300, 600, 900 and 1100 degrees C. The mechanical properties, dry unit weight, ultrasonic pulse velocity and thermal conductivity tests after 28 days of standard curing were performed to examine the impact of high temperatures on the mortar specimens. Microstructural deteriorations caused by high temperatures were investigated by scanning electron microscope. Mixture with an EVP/CAC ratio of 4 generally showed the best performance against high temper-ature in terms of compressive strength. Mortar with an EVP/CAC ratio of 6 showed the lowest thermal con-ductivity at both 20 degrees C and 1100 degrees C. According to the experimental findings, expanded vermiculite and CAC can be used to make fire-resistant cement-based lightweight composite coating materials and expanded vermiculite can also be employed as a lightweight aggregate in building insulation plaster applications