Fresh and mechanical properties of controlled low-strength material produced from industrial by-products

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This research aims to develop controlled low-strength materials (CLSM) made from bottom ash (BA), calcium carbide residue (CR), and fly ash (FA). The binder used in this study was divided into three types. The first type was BA:CR at the ratios of 85:15, 70:30 and 55:45 by weight. The second type was BA:FA at the ratios of 85:15, 70:30 and 55:45 by weight. The third type was ternary binder made from BA:CR:FA at the ratios of 55:15:30, 55:30:15 and 70:15:15 by weight. A water to binder ratio of 0.7 was applied throughout all mixtures while the flow of fresh CLSM was kept between 200-250 mm. The results showed that a mixture of BA:CR had a hardening time (at a resistance of 3,500 kPa) of 38 hours, while the mixtures of BA:FA and BA:CR:FA gave the hardening times of 16 and 21 hours, respectively, which were less than 36 hours and met the requirement of CLSM as specified by ACI 229R. The results also showed that the highest unconfined compressive strength was obtained from a mixture of BA:CR:FA at 55:15:30 with a maximum unconfined compressive strength of 14,190 kPa at 28 days. The mixture of BA:CR at a ratio of 70:30 and BA:FA at a ratio of 55:45 by weight gave the highest unconfined compressive strengths of 6,120 and 5,880 kPa at 28 days, respectively, which are high enough for producing CLSM.