Research On Key Preparation Technology Of Lightweight High Strength Gypsum Blocks

With the continuous development of China’s construction industry,the problem of building energy consumption has become increasingly prominent,It is urgent to develop energy-saving and environmental protection buildings.Gypsum block is one of the new wall materials which are widely used in building energy saving and building technology innovation in China.Gypsum block has the advantages of safety,environmental protection,fire resistance and adjusting indoor humidity.It is a new wall material with light weight,high strength,heat preservation,energy saving and waste-profiting.The development of lightweight and high-strength gypsum blocks has important practical significance for reducing building energy consumption,comprehensive utilization of solid waste and improving the living environment.In this paper,desulfurized gypsum was used as raw material to prepare gypsum whiskers,gypsum whiskers as lightweight materials to prepare gypsum blocks,and the proportion of gypsum blocks was optimized by"mixing design"in Minitab.The water resistance of gypsum blocks was also studied.The main study contents of this thesis are listed as follows:Firstly,gypsum whiskers were prepared by hydrothermal method from desulfurization gypsum of industrial solid waste.The effects of reaction temperature,reaction time,stirring speed,water-to-material ratio and raw material particle size on the aspect ratio and morphology of gypsum whiskers were studied by single factor experiment.The optimum gypsum whisker preparation process parameters were determined.The optimum process parameters were:reaction temperature is 140 C,reaction time is 2 h,stirring speed is 200 r/min,water-to-material ratio is 13:1,raw material particle size is 11.67μm.The prepared gypsum whiskers have the largest average length,the smallest average diameter and the largest aspect ratio,which is78.66.Secondly,using gypsum whisker and expanded perlite as lightweight materials,the effects of gypsum whiskers and expanded perlite with different contents on the apparent density,compressive strength,flexural strength,thermal conductivity,water absorption and softening coefficient of gypsum blocks are studied.By comparing the influence of gypsum whisker and expanded perlite on the performance of gypsum block.The experimental results show,it is concluded that under the same dosage and apparent density,gypsum whiskers can effectively reduce the strength loss of gypsum blocks,reduce the water absorption of gypsum blocks,and improve the softening coefficient of gypsum blocks.However,the thermal insulation properties are inferior to the expanded perlite.The gypsum whisker can replace the expanded perlite as a lightweight material to prepare the gypsum block.Thirdly,building gypsum is the main raw material,gypsum whisker is lightweight material,and appropriate amount of Portland cement is added to prepare gypsum-based composite cementitious material.Based on the“mixing design”in Minitab,the mixing ratio of gypsum-based composite cementitious materials is optimized,and the optimal mixing ratio is 52.2%for building gypsum,27.4%for Portland cement and 20.4%for gypsum whiskers.Based on the optimum mix ratio of gypsum-based composite cementitious materials,the apparent density of the prepared600mm?500mm?100mm solid gypsum blocks can be reduced to 965 kg/m~3,fracture load is 3260 N,which meets the requirements of JC/T698-2010"Gypsum Block"standard for apparent density and fracture load of blocks.Finally,the effects of Paraffin emulsion,polyvinyl alcohol emulsion and organosilicon hydrophobic agent on the water resistance of gypsum block were studied.The hydrophobic effect of organosilicon hydrophobic agent was obvious,and the organosilicon hydrophobic agent had little effect on the strength of gypsum block.The amount of organosilicon hydrophobic agent was 4%,the water absorption of the gypsum block at 2h and 24h were 20.5%and 22.3%,respectively,and the compressive and flexural softening coefficients were 0.62 and 0.63,respectively.Compared with gypsum block without organosilicon hydrophobic agent,the water absorption of the gypsum block with 4%organosilicon hydrophobic agent was reduced by 41%and 40%at 2 h and 24 h,respectively,and the compressive and flexural softening coefficients were increased by 51%and 47%,respectively.Meet the requirements of JC/T698-2010"gypsum block"standard for the softening coefficient of blocks.