Resilient and Permanent Deformation Response of Cement-Stabilized Pond Ash

Abstract

Cement-stabilized pond ash is often used as an alternative to conventional materials in compacted subgrade and subbases in pavements. The addition of cement to pond ash increases cohesion and improves strength. The effects of cement content, compaction energy, and moisture content on parameters such as deviator stress at failure, resilient modulus, and permanent deformations are studied by using cement dosages of 2% and 3%, two compaction conditions (standard and modified Proctor compaction), and three water contents [optimum moisture content (OMC), OMC−2%, and OMC+2%]. The stress-strain response of cement-stabilized pond ash is similar to cement-treated soils, which show peak stress followed by softening. The cement content is the dominating factor influencing these parameters. The influence of confining pressure and compaction energy is less significant in cemented pond ash. The peak deviator stresses and resilient modulus are the highest at OMC compared to dry and wet of optimum. The resilient modulus of cemented pond ash varies from 70 to 210 MPa, making it a suitable material for pavement applications. The Uzan and National Cooperative Highway Research Program models are used to predict the resilient modulus values of untreated and cemented pond ash. There are no distinct shakedown criteria available for multistage testing of materials. A criterion is proposed for establishing shakedown ranges for untreated and cemented pond ash based on permanent strain variation with the number of cycles. A grading criterion is also defined based on these parameters in which untreated pond ash belongs to the lowest grade and cannot be used in pavements. However, the addition of cement, as low as 2%, improves the properties of pond ash considerably and makes it a suitable material for compacted subgrades in pavements.