Testing Techniques for Evaluating the Shear Strength of Lime/Fly Ash Slurry Stabilized Soil
Lime slurry pressure injections have been successfully used to stabilize and control swelling and expansive soils and low-strength clay soils to depths of up to 40 ft (12 m). When the activity of soils is somewhat lower, or when soils have large void ratios, lime/fly ash (L/FA) slurry mixtures have been injected to fill voids. It has been postulated that this action creates stronger seams, helps to mend possible failure surfaces, and at the same time increases the overall stability of a slope by decreasing water infiltration. The investigation reported herein was undertaken to develop laboratory testing techniques suitable for evaluating the strength improvement realized by introducing L/FA into a soil mass in the form of seams. To accomplish this goal, six specimen configurations were conceived, and a total of 45 direct shear specimens, including 35 containing vertical and/or horizontal seams of L/FA, were tested. In addition to demonstrating the viability of testing techniques developed, the testing program resulted in a small data base on one soil stabilized with an L/FA slurry having a lime-to-fly ash weight ratio of 1:3.75 and a solids-to-water ratio of 7.6 lb to 1 gal (0.9 kg to 1 L).