An approach was developed to study the swell-shrinkage behavior of expansive soil samples in the laboratory under the action of the actual load to which the soil will be subjected in the field. The fatigue phenomenon due to cyclic drying and wetting has been under investigation, and this paper describes in detail the modified oedometer used in this investigation and the testing procedure adopted. Some typical test results are used to illustrate the fatigue behavior of undisturbed expansive soil specimens during cyclic drying and wetting.

Maximum dry densities of a variety of granular soils, ranging from silty sand to sandy gravel (Dmax = 9.5 mm), were determined by ASTM Test Methods for Maximum Index Density of Soils Using a Vibrating Table (D 4253-83) and by pluviation. The effects of various test conditions during pluviation were also investigated. The pluviation method offers several advantages compared to that of the ASTM method: higher dry density, no particle crushing, less effect of segregation, and better repeatability. In addition, the pluviation method can be performed with greater facility in less time.

A rolling device was developed in order to obtain plastic limits in a more expeditious and uniform fashion. The device enables the operator to perform the test on four to five specimens simultaneously. It also dictates that the very strict specification for rolling the soil threads into diameters of 3.2 ± 0.5 mm (0.125 ± 0.020 in.) is met. It removes all subjectivity from the plastic limit determination by governing the diameter of the threads as well as removing any error that may be introduced due to the uniqueness of the human hand. The design and operation of the device are detailed in this paper.

This paper describes the design, use, and results of a multiple leach-cell operation to test the changes in permeability and calcium removal of a lime-treated expansive clay under continuous water leaching. Seventy laboratory-prepared lime-treated clay specimens were subjected to continuous accelerated leaching for periods of 45 and 90 days with varying lime contents and compactive moisture contents. Permeability, leachate pH, and leachate cation changes were continuously recorded during the leach process. Results indicate that lime dramatically increased the soil's permeability, with maximum permeability occurring at the lime modification optimum (LMO). Leachate pH increased as the lime content of the soil increased but decreased linearly during the leach cycle. Calcium concentration in the leachate was lowest in specimens prepared at their LMO but increased as the lime content increased. There is strong evidence to suggest that calcium removal and permeability are in direct correlation to the complex ion interaction within the soil-lime mixture, and therefore the LMO is central in determining leaching effects on lime-treated soils.

This paper describes the measurement of the influence of capillary effects on the dynamic shear modulus of partially saturated sands. A Hall-type resonant column apparatus was used to perform the experiments. The materials tested included natural angular and subrounded sands, angular and subrounded sands with specified artificial gradations, and uniform angular and subrounded sands with various minus No. 400 sieve size fractions. Capillary stresses can significantly increase the shear modulus of unsaturated sands. Void ratio, confining pressure, degree of saturation, grain shape, and grain-size distribution are the primary factors affecting the shear modulus of partially saturated sands.