Effects Of Water-cement Ratio On Deep Mixing Treated Expansive Clay Characteristics
Pathivada, Siva Prasad
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The structures built on the unstabilized expansive soils are subjected to distress due to swell shrink behavior due to seasonal fluctuations. Medium stiff expansive clays with moderate and high PI were collected from two sites located at IH 820 N bound in Fort Worth, Texas. Deep soil mixing technique was proposed as a potential solution to counter the shrink swell movements of the expansive soil. These soils were stabilized using lime and cement as a whole and in combinations at different proportions in laboratory conditions simulating field deep soil mixing. Similar studies performed on soft soils revealed several factors mainly including binder dosage, binder proportion, curing periods and w/c ratio. The present study focuses on the effects of these factors on swell, shrink and stress strain behaviors of treated medium stiff expansive soils. The binder dosage and proportion (Lime: Cement) has varied from 100 to 200 kg/m3 and 100:0 to 0:100 respectively. The proportions of 100:0 and 0:100 represent 100% lime and cement respectively. The affects of above binder dosage rates and proportions on strength enhancements were studied at w/c ratios 0.8 and 1.3. All the treated samples were subjected to curing in 100% humidity room and were tested for UCS, bender elements, swell, shrink and suction after 7 and 14 days. Results show that the unconfined compressive strength values decreased with increase in w/c ratio. Maximum strength enhancements were noted at increasing binder dosages and cement proportions in the lime: cement ratio. No significant swell-shrink movements were observed for treated specimens at both the w/c ratios. Shrinkage strain magnitudes increased with increase in w/c ratio. Shear moduli of soils treated at 0.8 w/c ratio were greater than the same at 1.3.