The effect of zeolite and cement stabilization on the mechanical behavior of expansive soils

Abstract

Expansive clays are one of the problematic soils which impose significant economic damage to the construction projects due to their volume change during wet-dry conditions. Although cement is one of the most conventional materials of treating expansive soils, the increasing trend of cement production due to the growth in urbanization has resulted in substantial environmental issues like greenhouse gas emission and considerable raw material usage. To address such constraints, the present investigation aims at evaluating the effect of partial cement replacement with zeolite on the mechanical behavior of the cement-stabilized expansive soil. Four different cement contents (6, 8, 10, and 12%) and various percentages of cement replacement with zeolite (0, 10, 30, 50, 70, and 90%) were designated, then standard proctor compaction and unconfined compression tests were conducted. The results indicated that the addition of cement led to an increase in the maximum dry density (MDD) and optimum moisture content (OMC) of the soil-cement mixture, whereas increasing the zeolite content resulted in opposite trends. After 28 days of the curing period, cement replacement with 30% zeolite also resulted in achieving the maximum unconfined compressive strength (UCS). The maximum UCS improvement rate was obtained from 12% cement replaced with 30% zeolite in the specimen. Frequently, samples with higher cement contents well proved the efficiency of the optimum zeolite content. Besides, brittleness decreased by zeolite addition into the mixture observing failure modes of the stabilized specimens. Similar to previous test results, the highest stiffness (E50) was measured at 30% zeolite content. Finally, the active composition (AC) parameter was introduced, demonstrating that the highest strength improvement rate could be achieved by cement replacement with 30% zeolite in various cement contents and n/AC, having a power relation with mechanical behavior, could be used as a key parameter for prediction of the strength, as well.