EFFECTS OF SODIUM CHLORIDE ON THE ENGINEERING PROPERTIES OF EXPANSIVE SOILS

Abstract

This paper investigated the effect of sodium chloride on some geotechnical properties of expansive soil for highway pavement (subgrade) works. In this study, engineering properties including; Natural water content, Atterberg limits, specific gravity, compaction, free swell index, unconfined compressive strength, soaked and unsoaked California bearing ratio were determined in the laboratory and their behavior on stabilizing with various percentages of sodium chloride (0, 0.5, 1.0, 1.5. 2.0 and 2.5) investigated. From the study, plastic limit, liquid limit, plasticity index, linear shrinkage, specific gravity, free swell index and optimum water content values of the stabilized soil reduced, while the maximum dry density, California bearing ratio and unconfined compressive strength values increased. The highest reduction percentages of 60.42 % (131 to 51.85 %), 42.86 % (50.00 to 28.57 %), 71.26 % (81.00 to 23.28 %), 66.64 % (15.11 to 5.04 %), 83.43 % (115.00 to 19.05 %), and 28.57 % (28.00 to 20.00 %) in liquid limit, plastic limit, plasticity index, linear shrinkage, free swell index and optimum water content respectively; and maximum percentage increase of 11.38 % (1.67 to 1.86 g/m3 ,on maximum dry density), 31.78 % (29.20 to 38.48 %, on unsoaked CBR), 257.67 % (4.3 to 15.38 %, on soaked CBR), and 26.98 % ( 67.86 to 86.17 kN/m2 on unconfined compressive strength) were obtained on treatment of the soil with 1.5 % sodium chloride by weight. Treatment of the soil with sodium chloride has thus reduced its swelling potential and increased the strength