A synopsis of an extensive report prepared for the National Lime Association and FHWA is presented. Field projects originally constructed in the mid-1980s incorporating various methods of adding lime were used as the basis for the research effort. A total of 13 test sections constructed in four states were evaluated. Cores from the test sections and raw materials from the original suppliers for each project were obtained. The pavement condition surveys reported as part of the companion research effort were used to compare laboratory results with pavement performance. Laboratory testing included variations of existing moisture conditioning procedures: (a) no saturation, (b) partial saturation, and (c) full saturation. Results indicate that moisture-sensitive mixtures without lime will be significantly damaged even when the initial saturation step is eliminated. When lime is included in the mixtures, some level of saturation is needed to reduce significantly mixture strength. The increase in the number of freeze-thaw cycles from one to six follows the same trend - that is, mixtures without lime are significantly damaged, whereas mixtures with lime show only a moderate decrease in mixture strength with increasing numbers of freeze-thaw cycles. There is little difference in the mixture properties obtained for a given aggregate source when lime is introduced to either dry or prewet aggregate when preparing laboratory specimens. Little difference is noticed between the introduction of lime to prewet aggregate or lime with the binder inside the drum for field mixtures. The non-initial-saturation option provides the best agreement in relative ranking between conditioned resilient moduli values and the moduli values obtained for the cores. As the level of saturation is increased, the distinction between projects is lost. (Author/publisher)
Samenvatting