Experimental Investigation of Utilizing Industrial Waste and Byproduct Materials in Controlled Low Strength Materials (CLSM)

Laboratory experiments were conducted in this study to investigate the suitability and applicability of incorporating fly ash, bottom ash and paper sludge with various contents into CLSM mixtures. Fly ash was used as a substitute for Portland cement, bottom ash was added by partially replacing fine aggregate, while paper sludge was treated as a fibrous admixture. Physical and mechanically properties of the CLSM mixtures were examined through flowability, compressive strength, and splitting tensile strength tests. The test results indicated that both fly ash and bottom ash can be potentially used as basic materials for CLSM mixtures with desirable performances, and by limiting the amount of cement used in the mixture, the ultimate strength of CLSM could be easily controlled available for excavation. The strength of the CLSM mixtures were reduced to some extent by incorporating high content of fly ash, while the strength were significantly increased with high content of natural sand replaced by bottom ash. Due to the high water absorption of the paper sludge, the mixture with paper sludge added exhibited relatively low flowability, and it showed no benefits on enhancing compressive and splitting tensile strengths as common fibrous materials.