Thermo-physical and Mechanical Properties of Clay Bricks Produced for Energy Saving

Abstract

This study examined the production of porous and light clay bricks, which have low thermal conductivity and are made of a mixture of 10 wt%, 20 wt%, 30 wt%, 40 wt% pumice, 5 % expanded vermiculite, and clay. Pumice and vermiculite were added to the raw material of the soil brick as additives to create pores and provide thermal insulation in the buildings via the synergistic effect created by pumice and vermiculite. All of the raw materials were analyzed using XRF (X-ray Fluorescence), XRD (X-ray Diffraction), TG/DTA (Thermogravimetric/Differential Thermal Analysis), and SEM–EDS (Scanning Electron Microscopy-Energy Dispersive Spectrometry). Mixtures containing different concentrations of pumice and a constant concentration of vermiculite were prepared, dried, and fired at 950 °C for two hours. The properties of the samples were also examined: ignition loss, bulk density, apparent porosity, water absorption, compressive strength, thermal conductivity, and microstructure. The addition of pumice and expanded vermiculite dropped the samples’ bulk density from 1.93 g·cm⁻³ to 1.31 g·cm⁻³. As the addition of pumice and vermiculite increased, their porosity rates increased by 52 %, whilst their compressive strength decreased by 24 %. However, their compressive strength was higher than the value stated in the standards. The thermal conductivity of the samples containing 40 % pumice and 5 % vermiculite dropped from 1.041 W·m⁻¹·K⁻¹ to 0.439 W·m⁻¹·K⁻¹ exhibiting a decrease of 58 % compared to the reference sample. Consequently, the findings of this research reveal that pumice and vermiculite-added brick samples can be used as an insulation material in construction applications.