Chinese raw vermiculite: A potential additive for improving the thermal properties of calcium sulfoaluminate cement-blended mortars for applications in hot regions

Reducing the thermal conductivity (TC) of a cementitious building material can help to slow the rate at which it heats and cools. The present project aims to develop a new construction material with low TC for use in hot regions. The construction material is produced by blending Chinese raw vermiculite (CRV) with calcium sulfoaluminate (CSA) cement in mortar. CSA mortar specimens were cast and tested for a variety of properties, including dry density (σ), void content, ultrasonic pulse velocity (UPV), thermogravimetric variations, microstructure, TC, thermal diffusivity, and specific heat capacity. CSA mortars mixed with CRV had improved workability and σ. However, compared to plain CSA mortar, the compressive strength of the CSA mortars incorporating 60% and 100% CRV was reduced by 10% and 24%, respectively. This reduction in strength is still acceptable for non-structural applications, and the decrease in strength remains close to that of CSA mortars without CRV. The TC of CSA mortar with 0% fine aggregate replacement was 1.99 ± 0.17 W/mK, which is 95.07% higher than when 100% CRV was used as the fine aggregate replacement. The addition of CRV slows CSA mortar heating by 20%. The findings confirms CRV’s potential as an eco-friendly, energy-efficient construction material.