Research On The Application Of Fluorgypsum On The Masonry And Plastering

Fluorgypsum is the by-product of hydrofluoric acid production process which is the reaction of fluorite and concentrated sulfuric acid in the fluoride salt factory.At present,the total annual emissions of fluorgypsum exceeds 300 million tons in china, most of fluorgypsum are disposed by stacking yard,paving or landfill that is not only a waste of resources and space but also a big pollution to the environment.As an industrial waste,due to slow condensation,low strength and serious expansion, fluorgypsum can not be directly used as a building material.If it can be modified and transformed into gypsum building materials,turning waste into wealth,it is bound to play an active role in promoting on Chinese building materials industry.In this article,based on adding chemistry additives like CaO,stimulate agents and so on to make fluorgypsum fluoride retention and deacidification,the experiment focuses on the influences on the product performances of all kinds of hydraulic materials which were not determined to use in building materials containing fluorgypsum. And then focuses on the utilizations of fluorgypsum in masonry mortar and gypsum plaster which not only have been successfully developed but also have good social and economic benefits.The main contents and results of research are as follows:First,it is investigated that the performances of chemical composition and microstructure,mineral composition,proportion and specific surface area;adding a little cheap CaO to neutralize residual acid and soluble fluorine in fluorgypsum and make it transform to CaF2 which is insoluble;adding certain usage of salt stimulate agent to fully stimulate the activity of fluorgypsum that can shorten the setting time and raise the strength; And by means of researching the impact of hydraulic materials on the mechanical property of fluorgypsum binder.Second,using fluorgypsum and slag as the main materials,with a small amount of other activating agent and binder so on,fluorgypsum mortar is prepared,mainly for the autoclaved aerated concrete,and its water of normal consistency,the setting time,compressive strength,bond strength,resistance to shrinkage and frost and other main indicators can meet the standards of JC890-2001.Such mortal can replace traditional cement mortar,applied to the masonry wall project.Third,investigating the application of fluorgypsum in gypsum plastering.The results show that:the early strength of gypsum plastering can be improved with a certain amount of cement;gypsum plastering may be cracked when the stabilizer contents are fewer (≤0.15%);adding coagulant can significantly shorten the setting time;the sand content has greater impact on the performance of fluorgypsum plastering.When sand ratio is 1:2 and sand modulus is about 2,all the performance indicators of gypsum plastering can meet the standards of JC/T517-2004"gypsum plastering",and it has good frost resistance,resistance to shrinkage and cracking,and suits for interior wall plastering.