Experimental Research On High Strength Foamed Concrete And Application In Light-Weight Steel Structure

Under the trend to green, energy-efficient buildings in the construction industry, foamed concrete and light-gauge steel strucutre have been widely researched and applied at home and abroad. Self-insulation high-strength foamed concrete shearwall of straw board and light-guage steel combines high-strength foamed concrete and light-gauge steel strucutre. It pours high-strength foamed concrete into the cavity of prefabricated light-gauge steel strucutre to achieve higher load-bearing capacity, better thermal insulation and sound insulation property. Light-gauge steel columms replace longitudinal reinforcement in ordinary shear wall, and external transverse fibers of straw board replace transverse reinforcement. The new type of shear wall can be constructed in the facotry. In additon, straw board of low thermal conductivity replaces traditional wallboards to further improve the insulation performance.For self-insulation high-strength foamed concrete shearwall of straw board and light-guage steel, the following work is completed:A05 grade foamed concrete is studied. The best mix proportion to achieve mechanical property is determined by orthogonal test. Nominal water-cement ratio is 0.25, the fiber content is 0.3%, and fly ash content is 20%. The compressive strengh of foamed concrete block reaches 4MPa. By uniaxial compression test, low elastic modulus is found in A05 grade foamed concrete. Stress-strain relationship of foamed concrete is also found. And the simplified formula is proposed. Thermal conductivity ofA05 grade foamed concrte is 0.14 W/(mK).Seven full-scale specimens are tested under axial loading. The influencing factors include straw board, pouring foamed concrete or not, foamed concrete strength and thickness of the specimen. Bearing capacity of light-weight steel composite wall covered with straw board is close to those coverd with traditional board. Load-bearing capacity of specimen poured A05 grade foamed concrete is improved by 1 to 1.5 times. Bearing capacity of specimen poured A07 grade foamed concrete is improved by 2 times. When height of stud increases from the 89mm to 140mm, load-bearing capacity is improved by 39%-69%. Straw board has some effect on the bearing capacity. Low elastic modulus of foamed concrete henders the new composite wall to play a greater bearing capacity. Based on technical code of cold-formed thin-wall steel structures and Hooke’s law, capacity calculation method of new composite wall is put forward.Heat transfer resistance of a scaled specimen is test by calibrated hot box method, which results in 1.92(m2·K/W), meeting energy efficiency 65% of residential buildings in hot summer and cold winter zone. Thermal performance of three composite walls is simulated. It’s found that stud can reduce heat transfer resistance, and straw board has better thermal insulation property than traditional wallborads. Based on existing calculation method, the impact of stud is considered by heat transfer resistance coefficient. Heat transfer resistance coefficient has relationship with height of stud and the thermal conductivity of foamed concrete. A calculation formula of the coefficient is fitted. Stud can have more remarkable influence on the heat transfer resistance with higher altitude of stud and smaller thermal conductivity of foamed concrete.