Study On FGD Gypsum-Fly Ash Binder And New Type Block

FGD (flue gas desulphuration) gypsum-fly ash binder making up of FGD gypsum and fly ash mainly is one of the gypsum-based materials. As a green material,the gypsum-fly ash products not only fully use more than 90% of industrial by-products and waste material as raw materials,but also possess a lot of good properties. Multifunction & high-accuracy gypsum block is one of new types of wall materials made of hemihydrate gypsum and fly ash,and it has unique structure and outstanding performance.This dissertation has done a systematic study and test of the material's properties,production and application of hemihydrate gypsum-fly ash binder,according to the demands of multifunction & high-accuracy gypsum block's industrial production and application. The reasonable technical parameter and mix proportion of block's production have been fixed by testing the slurry's workability,hardened paste's strength,volume change and long-term properties. Moreover,the research on the core equipment for multifunction & high-accuracy block production has been completed through the equipment's improvement and the product's Pilot-plant testing,properties testing and field testing.The main findings and results of this dissertation are as follows:1 In hemihydrate gypsum-fly ash binder,the optimal content of fly ash is 25-30% with maximum addition 3% by mass of Ca (OH) 2 and 4% by mass of cement clinker.2 The additives containing alkalis oxide are not fit for hemihydrate gypsum-fly ash binder.3 Hot curing in 70 C dry-air is the optimal industrial curing mode and the best curing mode is hot wet-dry cycle curing of hardened hemihydrate gypsum-fly ash paste.4 Hardened hemihydrate gypsum-fly ash paste has a particular volume-change property:the paste's volume expands slightly instead of contracting in the early stage when drying after being saturated with water.5 Multifunction & high-accuracy block possesses good properties of sound insulation and heat insulation.The main innovations of this study are as follows:1 The material's properties research is conducted together with the research on theequipment and product line.2 The principle and means of designing and controlling hemihydrate gypsum-fly ash binder's hydration have been found and approved by the author.