Study On FGD Gypsum-based Aerated Concrete

The FGD gypsum-fly ash products has good performances such as energy-saving,using waste,environmental protection,insulation and so on.FGD gypsum-based binder has obtained extensive research.Aerated concrete has been concerned about increasingly because of its outstanding merits such as light weight, using waste,heat preservation and energy-saving.But the present aerated concrete was produced in the condition of autoclaved,the process is complex and it will use a lot of energy.In order to achieve the develop target of the wall material,it is necessary to research and manufacture FGD gypsum-based non-autoclaved aerated concrete.In this paper,the effects of mix ratio,w/c ratio,slurry temperature and curing conditions on compressive strength,bulk density and pouring stability of non-autoclaved aerated gypsum-based concrete were studied by experiments in the technology of non-autoclaved conditions.Eventually show that the rational content of FGD gypsum is 50～70%.The optimal content of fly ash is 25～30%;The maximum addition of cement clinker is 20%;The optimal content of lime is 8～12%; The best content of aluminum is 0.13%,and the amount of aluminum should be considered together with w/c ratio;The best w/c ratio is 0.47～0.50;Slurry temperature was controlled at 28～32℃.Heat conservation methods in 50～75℃is the best curing mode of FGD gypsum-based aerated concrete.Select reasonable ratio can get FGD gypsum-based aerated concrete that the compressive strength up to 2.8～3.3MPa and the bulk density can controlled under 750kg/m³.In this research,the production craft of products was studied.Through the experiments,it is obvious that some factors have effect on the property of gypsum-based aerated concrete in some degree,such as the sequence of commixing the slurry,the time control of mixing process.Through XRD and the SEM microscopic test methods,the microstructure and hydration mechanism of gypsum-based aerated concrete harden has studied.The result indicated that,the mainly hydration products are:CaSO₄·2H₂O,Aft and C-S-H.The crystalline state of hydrated product are better,a homogeneous and densified microstructure of aerated concrete was obtained.Used FGD gypsum and fly ash to prepare non-autoclaved aerated concrete in the lab is an innovative of FGD gypsum-based binder,which can save the equipments investment,reduce the consuming of energy.If it can be applied in the industrial production,it will not only benefit from the utilization of solid waste disposals and environmental protection,but also prominent economic benefits and social benefit,it is of far-reaching significance and great.