Abstract
The expansion of the swelling clays when subjected to moisture increase can be simulated to a hidden cancer. Growth of tiny molecules composed of silica tetrahedral and alumina octahedral can reach a stage that causes harm to light structures. The cost of annual maintenance is estimated into billions of dollars worldwide. Extensive research was conducted to stabilize this problematic soil using chemical methods. Stabilization of swelling clays using lime or cement is a well known efficient chemical approach. Research works on optimum lime or cement content is established for many types of clay. The use of lime is more popular than cement due to its lower cost. However, the cement is found to be better in reducing the expansion and improving the soil strength. In order to optimize the improvement with a yet tolerable cost it is intended to investigate treating the clay using a combination of cement and lime. The previous research works carried out by other researchers indicated that the optimum stabilization lime content is expected between 3.5 to 5% of the dry weight of the soil. A research study conducted on Al-Gaff clay shale focused on comparing the effect of adding a 4% lime content (The optimum content for lime only) with a lesser amount (2% by weight) consisting of cement and lime additives (1% lime and 1% cement). Stabilization of Al-Ghatt clay shale by using 4% lime reduced the swell percent by 3.3% in average. The use of 2% additive of cement and lime reduced the swell percent by 4.7% in average. The strength properties and bearing values were compared for the case of lime only and limecement additive. X-Ray Diffraction (XRD) tests were carried out for pure clay shale, clay shale with 4% lime additive and clay shale with 2% cement-lime additive. The effect on mineralogy is observed through the position and intensity of the peaks of common clay minerals. It is concluded that cement can be introduced with lime to achieve a better improvement with a reduced cost.