State of the art. I: Resilient response of unbound aggregates

The findings of an extensive literature survey on the structural response of unbound aggregates are discussed in two companion papers. In this paper, a state of the art is presented on resilient stress-strain characteristics of such materials, as well as different modeling techniques. The resilient response of aggregates is affected by several factors with varying degrees of importance. These are presented, and different views on the impact of each individual factor are discussed. Research efforts in the past have resulted in different mathematical models for predicting the resilient response of aggregates under repeated traffic-type lending. The models found in the literature are listed, and their advantages and shortcomings are reviewed. The permanent strain characteristics of unbound aggregates are considered in a separate companion paper.