WETTING AND DRYING CYCLES EFFECT ON DURABILITY OF GYPSUM SOILS TREATED WITH CALCIUM CHLORIDE OR CEMENT ADDITIVES
Abstract
The study consists of two stages: the first one is to improve the gypsum soil withcement or calcium chloride and the second stage is to expose these soilspecimens to series of wetting and drying cycles .Three soil specimens weretaken and marked as (A,B and C) with gypsum content (47, 32 and 23)%respectively .The results show that cement additive increases the cohesion of soilspecimens to 50% and collapse potential decreases with 65% and soil specimensimproved with calcium chloride increase the cohesion up to more than 70% andcollapse potential decreased about 70%. In the first cycle for wetting and dryingcycles for soil specimens improved with cement the cohesion decreases about25% and stays with the same ratio of the decreasing along the other cycle up totwelfth cycle. Collapse potential remains with the same value and is not affectedby cycling of wetting and drying. In the first cycle for soil specimens treated withcalcium chloride there is no effect in the first cycle whereas in the fourth cyclethe cohesion increased by 60% and in the eighth cycle the cohesion decreased8% and remains stable until the twelfth cycle. Collapse potential increases fromone cycle to another by (30-50) % for all soil specimens.
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