Experimental and numerical investigation of thermal enhancement methods on rammed-earth materials

Abstract

The renewed attention paid to rammed earth materials in recent decades is related to their sustainability, high thermo-buffering capacity and relatively low cost. The energy performance of rammed earth materials can be enhanced with stabilization. However, some of thermal enhancement methods have destructive side-effects. In the current study, the effect of three different methods was investigated on thirteen different alternatives of rammed earth materials to improve energy efficiency of buildings. These methods include using phase change materials, cementitious admixtures and external insulators. Thermo-dynamic parameters such as time lag, thermal conductivity and heat flux were measured experimentally using the box method. Numerical simulations were then implemented to validate the results of the experiments. A reasonable correlation with a minor deviation of 7% appeared between experimental and simulated data. Ultimately, to implement a comprehensive thermal study on rammed earth materials, considering both thermally-enhancive impacts besides environmentally-destructive side-effects, a multi-criteria optimization was conducted and the optimum alternative (stabilized rammed earth with 10% cement and compacted on optimum moisture content) was selected based on CO2 emissions and cost in addition to thermal parameters.