Development And Application Of Lightweight Aggregate And High Strength Lightweight Concrete

With the improvement of building energy efficiency requirements,the integration of lightweight,high strength and thermal insulation is the inevitable trend of the development of building materials.Lightweight foam concrete has the advantages of both foam concrete with lightweight and insulation and lightweight aggregate concrete with high specific strength,and has became the new development direction of high specific strength insulation material.The high specific strength and burning-free lightweight aggregate was prepared to study the relationship between the lightweight aggregate property and the material property,water consumption,nuclear-shell thickness as well as the curing method.The results indicate that the 700 class lightweight aggregate prepared by using the EPS particles with a diameter of 3mm as the core,a material ratio of C:FA:CH=5:4:1,and controlling the shell thickness of 2mm,a water content of balling of 15%and a curing condition under 75 ? has a cylinder compressive strength of 8.0MPa.Based on the foundation of core-shell and burning-free lightweight aggregate,the burning-free lightweight aggregate with PCM storage property is prepared by applying phase change material,and this kind of new material is using to prepare the lightweight aggregate concrete with a density of 1400kg/m~3,28 compressive strength of 12.5-18.2MPa and thermal conductivity of 0.26 W/(m·K)?0.30W/(m·K).The rheological properties of lightweight aggregate concrete is studied to analyze the relationship between rheological performance index(shear yield stress and plastic viscosity h)and the performance of fresh concrete as well as the pumping performance,the reasonable range of slurry viscosity is between 2.0Pa·s and 3.0Pa·s,and the reasonable range of yield shear stress is 75Pa-125Pa.The effect of porosity and pore size distribution on the properties of lightweight aggregate concrete is analyzed,and the effect of lightweight aggregate on the pore structure is analyzed by applying MIP method,the result is that the base bodies with lightweight aggregate proportion of 30%?40%?50%have an average pore size of 20.4nm?31.4nm?19.8?m and 28 compressive strength of 37.5MPa?21.3MPa?10.4MPa respectively.The pumping property of porous lightweight aggregate concrete is studied,and the results indicate that with a pressure bleeding rate BP of 35%-45%and V140 of 2?11mL,the pumping properties can be guaranteed.By referring to the composite material theory,the influences of slurry,lightweight aggregate,foam volume proportion on the lightweight aggregate foam concrete are studied by using mixed material designing method,and the regression equation of concrete properties is obtained by applying different fitting methods(the equation of 28 compressive strength is f28=52.06M-78.68G-62.36P+167.42M*G+38.90M*P+200.15G*P),and the lightweight aggregate foam concrete with high specific strength and low thermal conductivity is prepared by optimizing mixing proportion with different density.Compared with the ordinary lightweight concrete,the strength and insulation properties of optimized lightweight aggregate foam concrete show a significant improvement with 28 compressive strength of 30.3MPa,and thermal conductivity of 0.262W/(m·K).