Calcretic and ferricretic duricrusts of the Thar Desert, India: their geotechnical appraisal as a road paving aggregate

This paper presents the results of laboratory tests conducted to evaluate the suitability of calcrete and ferricrete as road paving aggregates. Most of these residual aggregates are gravel dominated (A-1 class) with low percentage of non-plastic fines. The maximum dry density (MDD) and optimum moisture content of these aggregates are controlled primarily by the size gradation and compaction energy. Specimens compacted using higher energy result in increase of MDD than those specimens compacted under low energy. Similarly, the California bearing ratio (CBR) also increases manifold (as much as 97.08%) when compacted under higher compaction energy. Aggregate impact values, a measure of toughness of these aggregates vary from 12.8 to 47.5%. Both calcrete and ferricrete exhibit special properties such as self-stabilization and increase in CBR after soaking. Obtained laboratory results on size gradation, CBR and aggregate impact values fulfils the Indian Road Congress (1978) specifications for the base and sub-base courses of water bound macadam (WBM) roads.