Experimental Study of Mechanical Stabilization impact on Improving Compressive, Tensile and Flexural Strength of Adobe

Iran is one of the oldest countries in the world benefiting from adobe-based architecture; a method which has long been forgotten in the contemporary architecture of country. Considering the important role of Earth Blocks such as adobe in the world’s contemporary architecture and the wealth of Iranian adobe-based monuments, it is necessary to continue contemplating on ways to optimize adobe to be used in the contemporary architecture as well as in the conservation of historical buildings. In the recent years, various techniques have been proposed for higher degrees of soil stabilization and adobe to strengthen the adobe structures. Mechanical stabilization as one of these techniques has been carried out to improve the quality of materials and subsequently increasing the durability of buildings. Compaction of earthen materials increases soil density and therefore improves earthen block behavior against damaging factors such as moisture and erosion. The present study is a quantitative research based on experimental observations and analysis. The method consists of field studies and empirical-laboratory methods. This study attempts to find out potential relationships between mechanical stabilization and mechanical and structural behavior of the adobe. In this respect the effect of soil density on compressive strength, flexural strength and tensile strength of the adobe is studies. Thus, adobe samples as control and experimental (compacted) groups were made from six soil types of six mines in a desert region of Iran, Ardakan city, Yazd province and their corresponding physical properties were measured. The construction method of all samples was alike except for the fact that experimental samples have undergone mechanical stabilization. The two groups were then examined and compared for compressive strength, tensile strength, and flexural strength tests and final results were studied and analyzed. The laboratory studies confirmed the positive relationship between dynamic compaction and mechanical strength. The results also showed that soil compaction in the experimental adobe results in an increase of Compressive strength by %79.43, Tensile strength by %42.42, and flexural strength by %75.00 compared to the control traditional adobe which lacks such compaction. Furthermore, by analyzing the results of grading of soil types and the percentage of clay in soils, it could be concluded that there is a meaningful relationship between the high percentage of clay in soils and mechanical behavior of the adobe bricks. Also, the study proved that the presented construction method in this study, i.e. integrating traditional adobe construction technique with mechanical stabilization, leads to better mechanical behavior of traditional adobe bricks. Hence, it could be stated that not only physical and chemical properties of soil but also construction method, has an integral role in improving mechanical properties of the adobe brick. Hence, it could be stated that not only physical and chemical properties of soil but also construction method, plays an important role in improving mechanical properties of the adobe brick.