Stabilization of Clayey Soil by Using Metakaolin and Sugarcane Ash

Soft clay is a natural soil that spreads in the south of Iraq and many countries in the world. It is a problematic soil causing trouble for the structures built on it because of, high water content, low shear strength, and high compressibility. This work investigated the geotechnical behavior of soft clay by using mix of Metakaolin (M) and Sugarcane Straw Ash in air (SCSAA).The experimental work contains the following tests: chemical tests, physical tests, Compaction tests and shear test. These tests were carried out on soil samples prepared from soft soil; the replacement materials by weight of dry unit weight for different percentages of M (4%, 6%, 8%, 10%) mix with different percentages of SCSAA (4%, 6%, 8%, 10%). The tests results showed that the best percentage for the plasticity test was M1B4. Also,the percentage which gave the best value for undrained shear strength test was M4B4 (135).Finally, the treatment soil is good sub grade materials and also can be used in highway sub-base material.