Effect of fineness and components of CFBC ash on performance of basic magnesium sulfate cement

The effect of fineness and components of circulating fluidized bed combustion ash (CFBC ash) on compressive strength, setting time and fluidity of basic magnesium sulfate cement was studied. The results showed that with the increment of the fineness of CFBC ash, the fluidity of cement paste increased, the setting time shortened and the compressive strength was slightly enhanced. The effects of the dosage of active SiO2, f-CaO and SO3 in CFBC ash on setting time, compressive strength and softening coefficient were also investigated. The experimental results indicated that with the increment of the active SiO2 dosage in CFBC ash, the setting time would prolong and softening coefficient would reduce. When the f-CaO dosage increased, the setting time would shorten. When the SO3 dosage increased, the setting time would prolong firstly and then shorten. Softening coefficient increased firstly and then reduced with the increment of the f-CaO dosage, but the softening coefficient firstly reduced and then slightly increased when the SO3 dosage increased. With the increment of the active SiO2, f-CaO and SO3 dosage in CFBC ash, compressive strength increased at first and then decreased. CFBC ash still has the filler effect, the morphology effect and the chemical effect. Comprehensive comparison, the superior fineness of CFBC ash is origin ash, and the optimum composition of CFBC ash is active SiO2 < 5%, f-CaO < 3% and SO3 < 1.75%. The results showed that CFBC ash could serve as favorable source materials for preparing basic magnesium sulfate cement, which may promote comprehensive application of basic magnesium sulfate cement and resource utilization of CFBC ash.