Field evaluation of soft highway subgrade soil stabilized with calcium carbide residue

Calcium carbide residue (CCR) is a by-product of acetylene gas production. Stockpiles of CCR continue to accumulate worldwide, in both developed and developing countries. Sustainable reuse options for CCR in civil infrastructures, such as road embankments, have been recently evaluated in the laboratory. However, to date there are limited studies on the actual field performance of CCR in stabilizing clayey soils in highway subgrades. In this study, a field trial was conducted to ascertain the viability of using CCR stabilized clayey soil as a highway subgrade course material. Quicklime was selected as a control binder in the field trial for comparison purposes. The construction procedures of the CCR and quicklime stabilizations in two field sections are presented. A series of field tests, including California Bearing Ratio (CBR) test, plate loading test, Benkelman beam deflection test, and dynamic cone penetrometer (DCP) test were undertaken after the embankment construction. The results indicated that in the top zone of the filled soil layers with 94% degree of compaction, the CCR stabilized subgrade soil exhibited higher values of CBR and resilient modulus, and lower values of resilient deflection and DCP Index relative to the quicklime stabilized soil. The field trial results indicated that CCR had negligible environmental effects and furthermore resulted in low construction costs. Based on the field test results, CCR was found to be a viable alternative binder for stabilizing soft subgrade soils. The outcomes of this research are significant from engineering, economic and environmental perspectives.