INVESTIGATION INTO THE EFFECTIVE PARAMETERS OF COMPRESSIVE AND FLEXURAL STRENGTH OF SOIL CEMENT MATERIALS USING NUMERICAL MODELLING (CASE STUDY: COFFER DAM OF BAKHTIARI DAM)

Soil cement is a mixture of Portland cement, soil and water, the constituents of which, due to the hydration of cement and compaction, bond together and make a dense and durable composition with low permeability and abrasion resistance. According to the de nition of ACI 116R, soil cement is a mixture of soil and a certain amount of cement and water which has been compacted to a high density. A more comprehensive de nition has been provided in ACI 230 IR, which de nes soil cement as a hard material with speci c engineering properties that is produced by the mixing, compaction and curing of soil, aggregate, Portland cement, additives and wa- ter. They are similar to roller compacted concrete; the main di erence between them being, however, the type and size of aggregate particles. Soil cement is principally made of round natural nes, while roller compacted con- crete is made of particles with a size of up to 19 mm. The soil cement mixture is usually used as protection for earth embankment slopes, while roller compacted con- crete is mostly used in massive elements such as gravity dams. All types of soil can be used in soil cement con- struction, except organic and plastic soil and reactive sand. The most ecient soils are those containing 5 to 35% of nes, passing sieve 200. However, soil containing more than 2% organic material is strictly unacceptable. Soil cement application in dam and pavement construc- tion has grown. Previous studies have investigated the e ects of cement content, water to cement ratio, and compaction level, on the strength of soil cement mix- tures. Some other factors a ecting the strength of soil cement are pozzolans and chemical additives which are not usually economical for use in large civil projects. In this research, the e ects of plasticity index and sand equivalent of soils on uncon ned compressive and ex- ural strength have been investigated. The results show that the compressive and exural strength of soil cement mixtures is dependent on the plasticity index and sand equivalent. Also, a numerical model developed for the co er dam of the Bakhtiari dam, and results, show that its structure is stable with soil cement material.