Assessment of the Suitability of Earth as a Construction Material from Experimental and Numerical Perspectives: A Critical Review

Earth materials have been used for thousands of years and are considered as one of the oldest construction materials. Recently, due to energy crises and the need to adopt energy-conservative solutions in construction sectors, earth buildings have drawn attention worldwide and reemerged since the 1950s. The materials, which are mixtures of natural soils and possible stabilizing materials, are considered as one of the foremost solutions to develop structures that are environmentally friendly due to several properties like low CO2 emission and thermal comfort. Also, the availability of such materials makes them the perfect solution for load-bearing residential house construction and no major processes are required prior to construction. However, understanding the behavior of such materials is challenging due to the large variation in their properties which is attributed to several factors like the sensitivity to water, density, curing conditions, etc. Therefore, in this paper, earth materials (both stabilized and unstabilized) are discussed in different terms including soil suitability, strength, and assessment methods or criterions. The effect of different parameters on the soil performance is analyzed based on previous studies and recommendations are presented, and a number of correlations are prepared based on the data of previous studies. Moreover, the criteria presented by many studies and standards to assess the earth performance are discussed thoroughly. Finally, numerical modeling of such materials is discussed. Such a study is expected to help both engineers and researchers to understand the role of different features on the earth materials and how to utilize them to come up with the optimum performance. Also, the study reveals the lack of development of a classification system that helps in selecting proper materials for earth construction in future.