investigation of the reliability of filter paper method on clay mixtures

One of the important factors that changes the tension in unsaturateal-saturated soils is the change in suction pressure of the soils. The change in soil stresses significantly influences the bearing capacity, shear strength, volumetric deformation, lateral soil pressures and slope stability. Therefore, it became so important to investigate the suction behavior and to measure suction accurate and reliable in order to prevent such related damages. In this study, the suction values of the zeolite bentonite mixtures having different properties were investigated and the reliability of the filter paper method, which is a laboratory test used for determination of the suction pressure, on zeolite bentonite mixtures was also studied. Soil samples containing 10% and 20% bentonite were investigated in two main groups based on total weight of the mixture. These two main group mixtures are divided into 4 sub-groups according to their varying soil index properties. The relation between the suction pressure values and the index properties such as water content, density and degree of saturation values of the soil were determined. Also, the reliability of filter paper technique for 10% and 20% zeolite bentonite mixtures was statistically explored and compared with the literature findings. The minimum number of experiments for ±10% accuracy band in 95% confidence level were determined.