Material Selection and Design for Moisture Damage of HMA Pavement

Abstract

Moisture damage is a primary mode of distress occurring in hot mix asphalt (HMA) pavements. Usually, the acid aggregate like gneiss must use some anti-stripping additive to resist water damage. Hydrated lime is best known as an anti-stripping additive since 1910. The purpose of this paper is to look at some aspects of the effects of aggregate chemical properties and hydrated lime on the dynamic mechanics and stripping behavior of hot mix asphalt. Two types of aggregates evaluated in this study were limestone and gneiss. The effects of the aggregates type were evaluated on four different aggregate gradations which were composed with the two aggregates in different proportion. And the hydrated lime has been used for HMA pavements to mitigate moisture-related damage in gneiss asphalt mixture. Laboratory tests for different asphalt mixture include Marshall Test, Frozen-thaw Cycle Test, Dynamic Modulus Test (DMT) and Indirect Tensile Fatigue Test (ITFT). Testing data and analyses demonstrated that different aggregate gradations have different mechanical properties. Hydrate lime has greatly contributed to moisture damage resistance in acid aggregate gneiss and enhanced the dynamic modulus. The modified with hydrated lime mixture composed with coarse gneiss aggregate and fine limestone aggregate also has better performance of the mixture against rutting, fatigue and thermal cracking. It can be concluded from ITFT tests that the fatigue life (load cycle times) of additive hydrated lime asphalt concrete is more than neat ones. At last, we can conclude that the selection and design that modified with hydrated lime and fine limestone aggregate replace acid aggregate could create multiple benefits in asphalt mixtures.