The effects of stabilizers on the thermal and the mechanical properties of rammed earth at various humidities and their environmental impacts

Abstract

The overall behavior of rammed earth (RE) as a low embodied energy construction method can be enhanced by using stabilizers. Several studies have been performed on cement and lime stabilized RE. However, studies on other additives, especially the sustainable ones, are limited. In this research, the effect of stabilizers including cement, pozzolan, microsilica, fiberglass, guar gum and phase change material (PCM) was evaluated on the performance of RE mixtures. The mixtures were assessed by considering the durability, shrinkage, thermal conductivity, mechanical properties and their sensitivity to the humidity. Then, the correlations were determined between the mechanical properties and the non-destructive wave velocity. Scanning electron microscope (SEM) used to analyze the reaction and the bond between the stabilizers and aggregates. The improvement in ductility and energy absorption of RE is significant by limiting the guar gum content. Pozzolan, especially used in conjunction with microsilica, improved the mechanical behavior of the RE mixtures. Fiberglass significantly enhanced the ductility, the tensile strength, and the energy absorption. It was concluded that aggregate volume fracture and admixture type are the most effective parameters on the thermal conductivity. Furthermore, the wave velocity is a proper tool to evaluate the suitability of the RE. More durable, sustainable and eco-friendly mixtures can be achieved by using a sufficient amount of guar gum and pozzolan with microsilica to improve the mechanical behavior of RE materials and also reduce the carbon footprint of RE materials.