Tensile strength of compacted and saturated soils using newly developed tensile strength measuring apparatus

This paper describes a newly developed tensile test apparatus which could be used for measuring the tensile strength of compacted and saturated soft soils with simple and quick testing procedure. Statically compacted soils; Kanto loam, NSF clay-sand mixture and silt (CFP-100)-sand mixture, and one dimensionally consolidated saturated NSF clay are taken as test samples. Unconfined compression test and initial suction test are also performed for Kanto loam to get their relationship with tensile strength. Maximum strength for compacted Kanto loam is obtained at around 50 similar to 60% of water content for all the samples prepared at three different dry densities (rho(d) = 0.66, 0.68 and 0.70 g/cm(3)) and the average ratio of unconfined compression strength to tensile strength is found to be 12.5. But it varies differently with water content at dry and wet sides. The effect of amount of finer particles and their size on tensile strength are also observed by changing the proportions of mixtures mentioned above. With the increase in NSF clay and silt proportions, the tensile strength is increased. Increment of tensile strength in the NSF clay-sand mixture is higher than that for the silt-sand mixture. This implies that with the decrease in the size of fine particles there is an increase in tensile strength. Relationship between the tensile strength and consolidation stress for saturated NSF clay is also shown.