Development of a New Soil Tensile Strength Test Apparatus

This paper describes a newly developed apparatus for measuring the tensile strength of compacted and pre-consolidated saturatedsoft to medium clayey soils. This apparatus is simple to use to perform a soil tensile strength. Two types of tensile molds are described and results obtained from them are compared. Repeatability of test results is also verified. Effects of water content, dry density, proportions of particle size and amount of fines present in the soil are also examined. Tensile strength and unconfined compression test results are compared. It was found that the ratio of unconfined compression strength (q_u) to tensile strength (q_t) for statically compacted Kanto loam soil is around 12.5. In case of compacted Kanto loam, maximum value of q_t and q_u is obtained around 50∼60% of water content for all the samples prepared at three different dry densities (ρ_d = 0.66, 0.68 and 0.7 g/cm³). Both types of strength decrease on wet and dry sides of this maximum value. In case of mixtures of NSF clay, silt and sand in different proportions, it is observed that with the increase in the amount of finer particles, both q_t and q_u increase. But with the increase in the size of finer particles, reduction in the strengths is observed. In case of pre-consolidated saturated NSF clay, tensile and unconfined compression tests are performed. Saturated NSF clay samples are prepared under the pre-consolidation stresses of 100, 200 and 300 kPa. The ratio of strength (q_u/q_t) obtained for this saturated NSF clay is around 6.