Modification of composite cementitious material produced by FGD gypsum-fly ash-GGBS

As the by-product of flue gas desulfurization process,FGD gypsum is not only cheap and has wide sources,but also has similar nature and advantages with natural gypsum.In this paper,the effects of different mineral admixture(fly ash,GGBS),different quantity of admixture and different mixture ratio on the performance of the FGD gypsum-based composite cementitious material were studied.The experiment results show that compared with empty sample,when choosing potassium sulfate as earlystrength agent,the initial breaking strength and compressive strength of the composite can be improved by 150% and 30.6% respectively.The strength can be improved by more than 100% with the alkali activation of quicklime and cement,while the use of fly ash and GGBS can ensure the strength and economic benefit.Through comprehensive consideration,the optimum mix of composite cementitious material is that:m(FGD gypsum)∶m(fly ash)∶m(GGBS)=40∶20∶40.