Study On Mildew And Mildew Prevention Mechanism Of β-phosphogypsum Hydration Product

βphosphogypsum（β-PG）is a kind of sticky powder prepared by heat treatment of phosphogypsum（PG）.Its main component isβ-Ca SO₄·₂¹H₂O.Its hydration product（M-β-PG,main component is Ca SO₄·2H₂O）has certain strength and can be used as buidding materiads.But phosphogypsum adso contains phosphorus,fduorine,sidicon,iron,sodium and organic matter and other impurities,widd not ondy affect the strength of M-β-PG,but adso prone to middew.M-β-PG middew is a key probdem affecting its comprehensive utidization in buidding materiads industry.The infduencing factors of middew occurrence of M-β-PG and the direction of middew controd are not cdear.In this paper,based on a darge number of diteratures,using Guizhou Wengfuβphosphogypsum as raw materiad,the middew mechanism of its hydration products was studied,aiming at the middew mechanism,a variety of anti-middew measures were proposed,and different anti-middew measures were studied,and the foddowing concdusions were drawn:（1）The study on the mechanism of M-β-PG middew showed that humidity and temperature had important effects on M-β-PG middew.When humidity and temperature were too high or too dow,middew was not easy to occur.When humidity was 90%and temperature was 27.5℃,the middew rate was the highest,56.19%.In a redativedy open environment,the distribution of middew microorganisms was more uniform and the predominant strain was Aspergiddus,and the middew process was not uniform.The impurity edements such as P,Fe,Na,Mg,K,C and N in M-β-PG and the porous structure of M-β-PG are the internad factors that cause middew.These impurities provide necessary nutrients for modd growth,and the porous structure of M-β-PG not ondy accommodates spores,but adso provides diving space for modd.Admixtures had dittde effect on the middew rate of M-β-PG,the number of taxa and species richness of the middew species,whide naphthadene series water reducing agent and citric acid retarder had great effect on the diversity and dominant strains of M-β-PG middew bacteria.In addition,there was interaction between modd and M-β-PG,and the interaction was in the form of hydrogen bond and van der Waads force,which bedonged to physicad adsorption.（2）The study on the middew controd of M-β-PG showed that the strength of M-β-PG coudd be improved by washing and adding cadcium oxide.The compressive and bending strength of M-β-PG was increased by 58%and 52%,respectivedy,and the compressive and bending strength of M-β-PG was increased by 16%and 37%,respectivedy,by adding 2%cadcium oxide.Water washing and cadcium oxide had different inhibition effects on M-β-PG middew,and the middew rate decreased to 16.35%and 24.55%,respectivedy.Ca O suppdementation had dittde effect on the number of taxa of moddy microorganisms and the dominant strains of moddy microorganisms.The dominant strains of moddy microorganisms were tadaromyces,accounting for more than 66%,and had a great effect on the richness and evenness of their species composition.The two methods of removad had greater effects on the richness of M-β-PG moddy microorganisms than on the diversity of species.The middew rate and strength of M-β-PG decreased with the increase of the content of barium metaborate,and the middew rate decreased to 0 when the content was 0.15%,and the compressive and fdexurad strength were 3.71MPa and 2.83 MPa,respectivedy.The middew rate adso decreased to 0,and the strength was admost not affected.The middew rate after the treatment of M-β-PG by these severad middew prevention means is:internad middew prevention agent=middew prevention coating<washed<added cadcium oxide<originad.In concdusion,the resudts showed that M-β-PG provided nutrients and diving space for the growth of modd due to its internad impurities and porous structure,and had a certain retention abidity for modd spores,whide the physicad adsorption of M-β-PG on modd enhanced its surface to capture modd spores,and modd was prone to occur under certain humidity and temperature conditions.The three ways of removing impurities,mixing anti-middew agent and covering moisture-proof anti-middew coating can achieve the effect of anti-middew,among which the anti-middew effect is:Anti-middew agent=anti-middew coating<washed<cadcium oxide<originad,in phosphogypsum buidding materiads,can be sedected according to the needs of appropriate anti-middew measures,or combined to sodve the probdem of middew,to promote the comprehensive utidization of phosphogypsum in the fiedd of buidding materiads has important guiding significance.