Effect of Initial Water Content on the Collapsibility of Natural and Cement-Treated Gypseous Soils

Abstract Soils that exhibit high volume change when its water content is changed are considered collapsible soils. Gypseous soils are one of the main types of collapsible soils which can be found in arid and semiarid areas. In this study, the effect of initial water content on the collapsibility properties of natural and treated gypseous soils with 5% of cement is experimentally investigated. The soils tested at different initial moisture content i.e. 5 %, 10 %, 15 %, 20 %. Two types of soil were used with different gypsum content 28.43 % and 43.62 % named soil 1 and soil 2 respectively. The soils were taken from Tikrit city in Saladin governorate – Iraq. The results show that the initial water content has significant effect on the collapse potential. The reduction in collapse for natural soils reaches up to 70 % when the initial water content was 20 %. Furthermore, the reduction in collapse for natural soils was greater than that for treated soils with different initial water content. It can be concluded that increasing initial water content can reduce the sudden collapse which is a major problem.