Impact of fines on the accumulated strain of unsaturated road base aggregate under cyclic loadings

Abstract

The property of a road base depends on its fine content (FC) and water content/suction. In this study, a cyclic loading test was carried out on road base aggregate with different FCs under controlled suction. The different effects of fines on the accumulated strain of road base aggregate at different FCs and suctions were identified. Under the saturated condition, the accumulated strain increased with FC due to the reduction of soil interparticle friction caused by the inclusion of fines. Under unsaturated conditions, the effect of fines on the accumulated strain depended on the inner structure of the soil. For the “coarse-grain-controlled soil” (FC in the range of 0%–4%), the accumulated strain increased with the increase of FC due to the reduction of interparticle friction, while for the “transition soil” (FC in the range of 4%–8%), the accumulated strain decreased with the increase of FC as the major impact of the fines shifted to the enhancement of suction, and the inclusion of fines is beneficial for this case; for the “fine-grain-controlled soil” (FC in the range of 8%–16%), the accumulated strain increased rapidly with FC as the effect of interparticle friction reduction dominated again.