Utilizing Chemical Treatment in Improving Bearing Capacity of Highly Expansive Clays

The foundations placed on near ground surfaces exert maximum contact pressures within the immediate vicinity of the soil-foundation contact line. The subsurface soil at this level and down to half the width of the foundation or beyond is considered within the strain influence zone responsible for most of the settlement of foundations. Stabilization using cement and lime is thought as a measure to improve the bearing capacity of Al-Qatif expansive soil in Saudi Arabia. The geotechnical engineers frequently recommend foundations to exert downward loads greater than the swelling pressure. This requires the supporting ground not to fail under bearing pressures and excessive settlement. Untreated Al Qatif soils were tested for unconfined compressive strength. Their respective bearing values were estimated using the Terzaghi approach and the Hoek-Brown failure criteria. Different dosages of lime and cement were added at different moisture conditions and curing periods. Improvement as calculated using Terzaghi and Hoek-Brown criterion were demonstrated for different types of treatment. This approach can be utilized to adopt higher bearing capacity values often needed in typical expansive soils.