Expansive soil remediation using cement kiln dust as stabilizer

Expansive soil is typically described as a hidden disaster. The presence of expansive soil in construction sites is associated with the deterioration of structures resulting from volume change and loss in shear strength accompanied by increased moisture. Given the high cost of damage inflicted by expansive soils on structures, the examination of possible methods for the remediation of such deposits of soil is extremely important. Recently, several improvement approaches, such as the use of stabilizers, have been employed for expansive soils. However, most stabilizers are perhaps harmful to the environment. In this regard, waste by-products, such as cement kiln dust (CKD), have been used as stabilizers. The utilization of such products has the added advantage of reducing carbon footprint and construction cost. It also diminishes environmental hazards and waste disposal costs. The main aim of this study is to evaluate the efficiency of CKD as a stabilizer for Al-Qatif expansive soils based on modifying the moisture-density (MD) relationship, swell-collapse potential (SCP), and unconfined compressive strength (UCS). To achieve the foregoing aim, three testing groups were executed, MD, SCP, and UCS. For each group, five series based on the amount of CKD added (i.e., 0 %, 2 %, 4 %, 6 %, and 8 %) were considered. The SCP and UCS series comprised several tests according to the curing period. The experimental results showed that CKD is beneficial for amending the Al-Qatif expansive soil. By adding CKD, the maximum dry density decreased, optimum moisture content increased, SCP fully diminished, and UCS substantially increased. The MD and SCP parameters were observed to be associated with the short-term CKD treatment, whereas the UCS was related to the long-term treatment.