Evaluation of Moisture Susceptibility of Asphalt Mixtures Containing Bottom Ash

Abstract

Bottom ash, as a by-product of coal-fired electric power plants, has recently been used in constructing transportation facilities. However, the use of bottom ash in asphalt mixtures is still in an early stage. The moisture resistance of asphalt mixtures containing bottom ash, which has not been adequately researched, is investigated in this study. Eight asphalt mixtures produced with one type of asphalt cement, two types of aggregate, three sources of bottom ash, and lime additive were evaluated using the principles in AASHTO T283. Analysis of test data indicated that granite mixtures had higher tensile strength values than did limestone mixtures in dry conditions. Addition of lime or bottom ash did not substantially change these values. All mixtures tested met the Superpave volumetric mix design requirement of tensile strength ratio ( TSR) after one freeze–thaw cycle. The addition of lime significantly improved the moisture resistance of the asphalt mixtures as measured by the TSR. With lime addition, aggregate type, bottom ash addition, and bottom ash source were all insignificant with respect to TSR. On the basis of TSR rate ( TSRR), the addition of lime significantly improved the moisture resistance of the asphalt mixtures subjected to multiple freeze–thaw cycles. Without lime addition, bottom ash played a role similar to that of lime in improving the TSRR for the materials tested.