Deltaic Lateritic Soil in 1:5:11 Mix Design for Producing Controlled Low-Strength Material (CLSM) for Pavement Backfill

Deltaic lateritic soil obtained from Emohua in Rivers State, Nigeria was studied to ascertain its suitability as a substitute to sand in concrete for producing controlled low-strength material (CLSM). Cement, coarse aggregate, as well as lateritic soil which replaced sand was combined in ratio 1:5:11 to produce lateritic concrete using varying water-cement (w/c) ratios at varying curing durations. Variation in the w/c ratios ranging from 0.2 to 0.5 at 0.1 intervals and the curing periods which varied between 7, 14 and 28 days were examined. As with the case with conventional concrete, strength development, as well as cement hydration took place after casting over the curing periods. Recent applications using CLSM recommends that a compressive strength of 8.3 N/mm2 or less is required for materials used as conventional compacted backfill soil or structural fillings. In a situation where future excavation is envisioned, it is recommended that the maximum long-term compressive strength of CLSM should generally have an upper limit of 2.1 N/mm2 for compacted backfill material hence, the lateritic concrete produced in this study using the 1:5:11 mix design at 0.2 w/c ratio, cured for 28 days which gave strength of 5.3 N/mm2 can be used as CLSM which primarily, can be utilized as a substitute for compacted backfill to sub-base and/or subgrade of flexible pavements. Where necessary, super plasticizer can be introduced to increase flowability of the lateritic concrete.