Durability of recycled lime-fly ash treated aggregates as pavement base materials: Chinese experience

This study investigated the durability of recycled lime-fly ash treated aggregates (RTA) as pavement base and sub-base layers. First, the both the physical and chemical properties of the waste lime-fly ash treated aggregate (WTA) materials were tested. Then, RTA were designed according to the specifications and further examined for its long-term durability properties including shrinkage, freeze-thaw, fatigue and permeability. The RTA investigated were actually cement-stabilized RTA, a stabilized blend of 70% WTA and 30% virgin aggregates for base layer, and a stabilized 100% WTA for sub-base layer, respectively. Test results were as follows: 1) WTA particle surfaces were becoming rougher as the size of the particles decreased, which was closely related to the degree of shrinkages of the RTA. 2) Both the value of moisture shrinkage and the weight of water loss of RTA increased as the curing time of RTA increased, indicating the contribution of the weight loss to the shrinkage of the RTA. 3) The total thermal shrinkage increased as temperature decreased although its rate of increase decreased for every temperature increment. 4) Overall, the fatigue life of RTA was short, indicting its structure was closer to that of suspension dense type.