The effect of high temperature on lightweight concretes produced with colemanite coated pumice aggregates

• Pumice aggregates were coated by cement and colemanite mixture.
• Usage of colemanite coated aggregates prevents concrete from strength loss.
• Unit weight of concrete with colemanite coated aggregates increases.
• Weight loss of concrete with coated aggregates increases under high temperature.

Concrete is a non-combustible material. But it is known to have serious changes in its physical, chemical and mechanical properties when exposed to high temperatures. In this study, the surface of large pumice aggregate was coated with cement + colemanite (CLM) dual mixtures (0%, 7.5%, 12.5% and 17.5%). Lightweight concretes were produced by using coated aggregates. Then by exposing to temperatures at 20 °C (Control), 200 °C, 400 °C and 600 °C, the unit weight, compressive strength, ultrasonic pulse velocity and weight loss of concrete samples were determined. Also, in order to identify the internal structural properties of the samples, DTA-TGA and SEM-EDS analysis were performed. As a result of the study, the optimum value was obtained from 12.5-CLM samples. It is determined that the lightweight concretes that would be produced with pumice aggregates coated with cement + colemanite dual mixture would have a high performance against high temperature.