Study On Preparation Technology Of High Solid Waste Content Ultra-light Foamed Cement Insulation Board

The ultra-light foaming cement insulation board belongs to the inorganic porous green energy-saving building material,which has the characteristics of excellent heat preservation,fire prevention and low production cost.As the insulation layer of the building exterior wall,not only can it have better heat preservation effect,but also the fireproof grade reaches A.The market is relatively inexpensive and is popular in the market.Although ultra-light foaming cement has many advantages as building exterior wall insulation materials,there are still some shortcomings in performance,which need to be further optimized.In view of the current problems of high thermal conductivity,low strength,high water absorption and low solid waste,the ultra-light foamed cement insulation board has been studied in the following four parts:First of all,on the basis of the existing basic mix ratio and on the premise that the dry density is less than 160kg/m³,the effects of the speed of mixer,the mixing time and curing technology on the performance of ultra-light foaming cement are studied.The optimum preparation technology of polymer modified ultra-light foaming cement was determined as follows:mixer speed 1200 r/min,stirring time 210 s.After molding,the cement was placed in the standard curing room for 7 days,and then in the molding chamber?Spring and Summer temperature:20±5?,Relative humidity:30%-60%RH;Autumn and Winter temperature:15±5?,humidity 45%-65%RH?to the specified age.The main performance indexes of ultra-light foaming cement formed under the preparation process are:dry apparent density159.4kg/m³,28d compressive strength 0.43MPa,thermal conductivity 0.051W·m^-1K^-1,water absorption rate 22.4%.Secondly,improve the solid waste dosage of ultra-light foaming cement.In the basic mix ratio,the fly ash content accounts for 30%of the cementitious material,and the fly ash content is increased to 50%,and the bottom slag and waste are added.Foamed cement powder,using early foaming cement powder to prepare early strength agent,etc.,to increase the amount of solid waste,and increase the type of solid waste added.When the fly ash content is increased to 50%,the main performance indexes of ultra-light foaming cement are obtained:dry apparent density 156.5kg/m³,28d compressive strength 0.31MPa,thermal conductivity0.050W·m^-1K^-1,water absorption rate 22.6%.And by incorporating the self-made composite early strength agent,the strength of the ultra-light foaming cement can be significantly improved,and the main performance index of the foamed cement insulation board prepared when the optimum amount of the composite early strength agent is obtained:dry density of 157.9 kg/m³.The compressive strength is 0.39 MPa,the thermal conductivity is 0.050W·m^-1K^-1,and the water absorption rate is 22.7%.The hydration products,porosity and pore size distribution were analyzed by X-ray diffractometry?XRD?,scanning electron microscopy?SEM?and X-ray tomography?X-CT?,and the enhancement mechanism was analyzed.Next,the ultra-light foamed cement was prepared by replacing the Portland cement used in the test with the sulphoaluminate high-activity powder prepared by Shandong University,and its performance was optimized by changing the type of early strengthening agent.Foamed cement can be prepared by using thioalicylic acid system high active powder to prepare foamed cement.The dry density and compressive strength of foamed cement prepared by thioalicylic acid powder instead of Portland cement are low,which are 140.1 kg/m3,0.09MPa,respectively.However,due to the large pore size of the product,the thermal conductivity of the product is 0.057 W·m^-1K^-1.By adding the self-made compound early strength agent to improve the properties of sulphate aluminium foamed cement products,the pore structure of the foamed cement can be improved,the pores are fine,the distribution is uniform,and the thermal conductivity is significantly reduced.Increase of compressive strength to 0.15 MPa.The main performance indexes of foamed cement prepared by the sulphoaluminate high-activity powder are as follows:dry density 143.2 kg/m³,compressive strength 0.15 MPa,thermal conductivity 0.044 W·m^-1K^-1,water absorption 35.1%.Finally,on the basis of the experimental mix ratio of 50%fly ash?accounting for the quality of cementitious material?,the effect of waterproof coating on the water absorption of ultra-light foaming cement was studied by waterproof treatment on the surface of foamed cement.When the surface of foamed cement specimen is coated with a layer of LSD waterproof coating for 14 days,the water absorption can be reduced to 0.51%,but the curing time is longer.When a layer of HY polyurethane waterproof coating is coated on the surface of foamed cement specimen for 1 day,the water absorption can be reduced to 0.1%,which meets the requirement of less than 1%water absorption.Painting a layer of LSD waterproof coating or a layer of HY polyurethane waterproof coating can be used as a priority for industrialization.