Influence of Tensile Strain at Failure on Flexural Properties of a Cementitiously Stabilized Subgrade Soil: Fid-Bau Portal

Influence of Tensile Strain at Failure on Flexural Properties of a Cementitiously Stabilized Subgrade Soil

Ghabchi, Rouzbeh

AbstractFlexural properties of subgrade soils play an important role in the overall performance of pavements. In this study, a series of laboratory tests and finite-element analysis were conducted to evaluate the effect of the stress-strain behavior of cementitiously stabilized soil (CSS) on its flexural fatigue life. Three different amounts of cement kiln dust (CKD), namely 5, 10, and 15% (by weight), were mixed with soil, and beam specimens were prepared using these three mixes. Modulus of rupture (MoR) tests were conducted on the prepared specimens to measure flexural strength and tensile strain at failure. Four-point bending beam fatigue tests were conducted on CSS specimens to evaluate their flexural modulus and fatigue life of each mix. Also, finite-element models of the MoR tests were developed using a concrete damage plasticity model for the CSS material. The MoR test results showed that the flexural strength increases with an increase in the amount of CKD. However, the failure strain was not found to follow any specific trend. The lowest and the highest strain values at failure occurred with the use of 10 and 5% CKD, respectively. The results of the four-point bending beam fatigue tests indicated that the flexural modulus of stabilized soil increased with an increase in the amount of CKD. Also, it was found that mixes with the highest tensile strain at failure in MoR testing (CSS specimens with 5% CKD) showed the highest fatigue life, whereas the specimens with the lowest tensile strain in MoR testing (CSS specimens with 10% CKD) showed the lowest fatigue life. The results from the finite-element models developed for MoR tests were found to be in agreement with the test data. Also, it was concluded that the Euler-Bernoulli theory can be used for calculation of tensile strain at the bottom of the cementitiously stabilized subgrade soil, with an acceptable level of accuracy. The flexural properties of CSS specimens are expected to be useful in estimating fatigue performance of pavements with cementitiously stabilized subgrade soil.