Limit tests performed on a clay indicate a liquid limit of 67 percent and a plastic limit of 32 percent. From a hydrometer analysis to determine particle sizes, it is found that 40 percent of the sample consists of particles smaller than 0.002 mm. From this information, indicate the activity classification for this clay and the probable type of clay mineral.

Refer to the soil in Problem 4.5. Using the Casagrande plasticity chart, graphically estimate the shrinkage limit of the soil as shown in Figure 4.22. 4.5 The following data were obtained by conducting liquid limit and plastic limit tests on a soil collected from the site. Liquid limit tests: Plastic limit test: PL = 19.3% a. Draw the flow curve and determine the liquid limit. b. Using the Casagrande plasticity chart (Figure 4.21), determine the soil type.

The properties of seven different clayey soils are shown below (Skempton and Northey, 1952). Investigate the relationship between the strength and plasticity characteristics by performing the following tasks: a. Estimate the plasticity index for each soil using Skemptons definition of activity [Eq. (4.28)]. b. Estimate the probable mineral composition of the clay soils based on PI and A (use Table 4.3) c. Sensitivity (St) refers to the loss of strength when the soil is remolded or disturbed. It is defined as the ratio of the undisturbed strength (f-undisturbed) to the remolded strength (f-remolded)) at the same moisture content [Eq. (12.49)]. From the given data, estimate f-remolded for the clay soils. d. Plot the variations of undisturbed and remolded shear strengths with the activity, A, and explain the observed behavior.

The subsurface characteristics for a highway pavement rehabilitation project in the southeastern United States are shown in a boring log in Figure 5.13. The highway structure consists of the asphalt pavement underlain by four different soil strata up to a depth of 20 ft, after which the boring was terminated. Some data on the grain size and plasticity characteristics are also provided for each stratum. Perform the following tasks: 1. Determine the AASHTO soil classification and the group index (GI) for each layer. 2. Determine the most probable group symbols and group names for the various layers according to the Unified soil classification system. Use Table 5.3 and the soil characteristics given in the boring log.