Effect of Liquid Polyvinyl Acetate and Micronized Calcium Carbonate on Strength Parameters of Silty Sand Soil

Abstract

Improvements in the strength characteristics of soil are noteworthy in geotechnical engineering. Many engineering problems emerge in silty sand soil because the silty fraction generally has low strength properties. High dispersion in such soil at a construction site illustrates the necessity of studying and surveying new methods of improvement of its strength properties. One of the methods used to improve soil strength is chemical additives. In the present research, the effects of the addition of polyvinyl acetate (PVA) and micronized calcium carbonate (MCC) on the strength of silty sand soil have been investigated. PVA and MCC were mixed with soil in different proportions (1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 5% and 6% (wt.)) for unconfined compression testing and (1%, 2%, 3% and 4% (wt.)) for direct shear strength test under different curing time (1, 7, 14 and 28 days). SEM images were acquired before and after mixing to determine changes in the properties of each sample. It was found that the addition of MCC and PVA to silty sand soil increased the unconfined compression strength (UCS) by 2.5% and 4%, respectively, comparing to untreated soil. An increase in the MCC and PVA contents decreased the UCS of the soil. It was also demonstrated that the addition of PVA more effectively improved the soil strength properties than did MCC. The addition of both of materials increased the shear strength of the soil, but this increase was greater for cohesion than for the internal friction angle. It was also demonstrated that increasing the curing time in stabilized samples of both additives increased the UCS more than 80% in the first 14 days.