Soft Clay Treatment Using Geo-Foam Beads and Bypass Cement Dust

Abstract

Soft clays are usually classified according to their undrained shear strength, Cu. Values of Cu less than 12.5kPa are associated with very soft clays, whereas, soft clays possess undrained shear strength ranging between 12.5kPa and 25kPa. In addition to the low shear strength of soft clays, they experience high compressibility upon loading. This is why soft clays are considered as problematic for foundation purposes. Also, Geo-foam is an industrial material, characterized by a very low unit weight (average of 20kg/m3) compared to that of the soil. Having a density ranging from 1.0% to 2.5% of that of soil EPS possesses a compressive strength ranging between 70kPa and 140kPa and an elastic modulus ranging between 5MPa and 12MPa, According to Horvath (1997). EPS Geo-foam blocks are used in a wide range of geotechnical applications as a light weight fill. So, the main objective of this study is to investigate the geotechnical properties of soft clay with Geo-foam beads and bypass cement dust. Also, investigate the possibility of preparing low strength excavatable fill mixtures. For studying the effect of (Geo-foam beads + CBPD) / soft clay on fluid-state and hardened properties of new fill, experimental work was carried out on two groups of mixture (A&B). Different ratios of (Geo-foam beads + CBPD) were added to the mixture to study its effect on flow consistency, dry unit weight, unconfined compressive strength, and shear strength. The results of test conducted on the materials illustrated that, cement bypass dust and excess foundry sand can be successfully used to procedure self-compaction, self-leveling excavatable flowable fill material. The unconfined compressive strength of the studied mixtures without Geo-foam ranged between 271.8kPa and 1405.14kPa at CBPD between 3.88% and 18.63%. The Cohesion values for group with Geo-foam with ranged between 50kPa and 20kPa at Geo-foam between 0.32% and 1.35%. The friction angle of group with Geo-foam with ranged between 10 and 22kPa at CBPD between 0.32% and 1.35%.