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Long Term Dry and Wet Effects on the Engineering Behavior of Subgrade Soil with High Amount of Soluble Salts using Low Cost Stabilizers Original Article, D74 Ibrahim S.F., Ibrahim M.S., Abd hak H. J. Civil Eng. Urban. 4(5): 492-500. 2014 ABSTRACT: The performance of pavements depends upon the quality of subgrades. A stable subgrade and properly draining pavement help to produce a long-lasting pavement. Subgrade soil provides support to the remainder of the pavement system. This study is performed to evaluate the effect of total soluble salts (T.S.S.) on the strength of subgrade soil brought from Al-Mahmodia city south of Baghdad. Chemical and physical test, carried out on the soil sample, indicate that, the soil is lean clay of (CL) group according to the Unified Soil Classification System (U.S.C.S.). The soil sample contains about (15.685%) by weight of (T.S.S.) content. Different stabilizers are added to the subgrade soil to study the influence of these stabilizers on (T.S.S.) and the strength of subgrade, the stabilizers are (5% lime, 2.5% calcium chloride, 6% kaolin, 6% Rice Husk Ash and 5% saw dust). California Bearing Ratio (CBR) test is determined for the natural soil and different stabilizers with different number of blow per layer (10, 25 and 56) for (4-days) soaking periods under (10 Ibs.) surcharge load. The number of blow per layer and (CBR) value, required to achieve (95%) relative modified proctor compaction are determined from the results of different number of blow (10, 25 and 56) and soaked for (4-days). The (CBR) value of the natural soil at 95% relative modified proctor increases by about (48%, 66.1%, 36.1% and 38%) for the (2.5% CaCl2, 5% lime, 6% RHA, 6% kaolin) respectively. While the CBR value of soil with the (5% saw dust) decreases to (29%). The (T.S.S) is reduced after the addition of the different stabilizers. Durability test (long term soaking) for the subgrade stabilized with (6% RHA) and compacted at 95% relative modified proctor is conducted, the results of soaking showed reduction in both (CBR) value and (T.S.S) with the time. Keywords: Strength, Rice husk ash, Total soluble salts, Durability, Calcium chloride منبع: [Hidden Content] دانلود: [Hidden Content].,%204%20(5)%20492-500,%202014.pdf J. Civil Eng. Urban., 4 (5) 492-500, 2014.pdf