Lime Requirement for Stabilization

Abstract

Lime is used in construction as a rapid and economic method of improving the strength and stiffness characteristics of clay soils. For economical design, an engineer must know how much lime is required to initiate the required improvements. If lime stabilization is to be compared with alternative solutions in the early stages of a project, it must be possible to make this assessment rapidly and with the minimum expenditure on additional specialist testing. The ASTM Standard Test Method for Determining Stabilization Ability of Lime (MDSAL) aims to determine the quantity of lime required for stabilization using simple methodology to generate results quickly. Additional, much lengthier testing is recommended to verify the lime requirement if lime is considered feasible following MDSAL testing. Problems have been found in the execution of the test and interpretation of results, concluding in inconsistency in the lime quantities calculated. This inconsistency could lead to substantial differences in the estimated cost of the overall scheme and possibly to the unwarranted rejection of lime stabilization as a potential solution. The methodology of the MDSAL test through practical experimentation is reviewed and recommendations for its future use are made. The sensitivity of the test to changes in lime quality, volume of water added, and temperature of the soil-water-lime mixture is examined. It is shown that, although extremely sensitive to changes in these parameters, a revised interpretation of test data means that a reliable and consistent result can be achieved. The scientific basis for this revised interpretation is also demonstrated.