01628197

Component

Fine-grained soils are widely used as a subgrade material and have high moisture susceptibility. The soil-water characteristic curve (SWCC) shows the relationship between the moisture content and suction, which is a critical characteristic for evaluating the moisture susceptibility of soil. Therefore, it is very significant to determine the moisture content to explore their engineering properties related with the moisture content, such as shear strength, resilient modulus. In this study, the methylene blue values (MBV) for 15 fine-grained soils were measured by using a new methylene blue test. Subsequently, the relationship between MBV and plasticity index (PI), the percent passing No. 200 sieve (P200) was established. The SWCCs for the selected 15 fine-grained soils were gained by the pressure plate test and the four fitting parameters of the Fredlund and Xing’s model were determined. After that, the correlations between the four fitting coefficients and MBV values were established and validated; the suctions with the degree of saturation under different MBV values were predicted. The results show that PI, P200 has a positive correlation with MBV. At the same time, the slope parameter, bf, in the SWCC equations was found to be associated with the moisture susceptibility of fine-grained soils. A higher bf value indicates that the material is more moisture susceptible. In addition, the lower the MBV/PI/P200 shows the lower suction value at the same degree of saturation; on the other hand, the higher the MBV/PI/P200 shows the higher suction. Therefore, the moisture holding capacity of fine-grained soils increases with the increasing MBV, PI and P200. Finally, the estimation method to predict SWCC based on the Fredlund and Xing’s model using MBV is rational, which is capable of generating the SWCC more efficiently than previous laboratory method, and it can even be used in field investigations because the methylene blue test requires limited portable test equipment.

This paper was sponsored by TRB committee AFP60 Standing Committee on Engineering Behavior of Unsaturated Geomaterials.

01618707

17-06564

English

13p

2017

Transportation Research Board 96th Annual Meeting

Digital/other

Figures; Photos; References; Tables

Fine grained soils; Moisture content; Plasticity index; Saturated soils; Soil suction; Soil water; Test procedures

Methylene blue test

Geotechnology; Highways

Transportation Research Board Annual Meeting 2017 Paper #17-06564

TRIS, TRB, ATRI

Dec 8 2016 12:41PM