Engineering properties of controlled low-strength materials containing co-fired fly ash

Abstract

In this study, it investigated the effects of adding a mixture of circulating fluidized bed co-fired fly ash and bottom ash on controlled low-strength material (CLSM). Experiment variables were as follows: (1) mixing of co-fired fly ash, cement, and pulverized coal fly ash in various proportions to evaluate the effectiveness of using co-fired fly ash as cementitious material in CLSM; (2) mixing of bottom ash and natural fine aggregate in various proportions to evaluate the effectiveness of using bottom ash mixture as aggregates in CLSM. The water-cement ratio of CLSM was fixed at 0.85. Assessments were conducted using a lump flow test, flow consistency test, ball drop test, chloride ion measurement, compression strength test, and length change test. Test results indicate the following: (1) increasing the replacement ratio of co-fired fly ash and bottom ash decreases flowability; (2) the addition of co-fired ash (containing chlorine), with bottom ash increases the amount of chloride ions in CLSM; (3) the addition of co-fired fly ash reduces setting time; (4) the CaO, SiO2, and Al2O3 in co-fired fly ash and bottom ash increase the compressive strength of CLSM; (5) the CaO contained in the mixture of co-fired fly ash and bottom ash causes CLSM to expand.