Soil-Suction Measurements Using the Filter Paper Method to Evaluate Swelling Potential

Soil suction is directly related to the free energy of the pore-water in a soil, thus it can be accurately used to qualitatively classify the relative swelling potential of expansive soils. The relationship between the affinity of soil to retain water and suction can be determined based on the filter paper technique of total suction measurement. The advantage of using filter paper to quantify soil suction is its potential to provide a wide range of reliable accurate information easily and cheaply. This paper evaluates total potential suction value by controlling the variables for measurement of the water content of filter paper that was in direct contact with soil disks in an easily installed sensing chamber for seven days. After the filter papers had reached suction equilibrium with the surrounding soil, the moisture content was carefully measured and soil suction values were related to a total-suction value through calibration curves obtained from an established correlation for equilibrium filter papers over salt solution of known total suction. The obtained values of total suction were thereafter used to estimate the expansiveness of soils. According to the experimental data of the suction test, the soil in consideration falls in high expansive potential.