Effect of aging on fatigue performance of hydrated lime modified bituminous mixes

Abstract

Hydrated lime has traditionally been used as filler primarily for its ability to improve the moisture resistance of bituminous mixes. However, studies carried out in the past showed that the addition of hydrated lime is also useful in improving the resistance of bituminous mixes to rutting, fatigue and aging. The effect of lime in increasing the stiffness of the mix can be beneficial to thicker bituminous pavements, which will be in stress control mode of fatigue. The reduction in the rate of aging due to lime can also benefit the performance of mixes due to reduction in brittleness and improvement in the healing characteristics. The present work explores the effect of hydrated lime modification of bituminous mixes on their fatigue performance. The effect of two different methods of lime addition, wet and dry, was investigated. The influence of short-term and long-term aging of the mixes on the fatigue characteristics of bituminous mixes was examined. Ten different combinations of mixes with two virgin binders, four lime modified binders and four mixes with lime added as filler were considered in the investigation. The results of laboratory tests conducted for determination of the moduli of elasticity of mixes and the fatigue performance models obtained for different mixes, under two different aging conditions, combined with the mechanistic analysis of typical bituminous pavement sections established the beneficial effect of lime in improving the fatigue lives of bituminous layers, especially for thicker pavements.