Experimental Research On The Durability Of Assembled Foamed Concrete Filled Wall

With the rapid development of China's economy,the demand and consumption of energy are increasing day by day.However,there are prominent problems of low utilization rate and serious waste of energy in China.The construction industry is a major energy consumption and waste in China.The poor thermal insulation performance of the enclosure structure is an important reason for this result.The wall is the most important enclosure structure.However,there are many shortcomings in the traditional thermal insulation forms of the wall.The traditional construction method of the wall using cast-in-place concrete or masonry blocks has low construction efficiency and serious pollution,which is not conducive to the building industrialization development guided by China's current policy.Foamed concrete has many advantages,such as good thermal insulation,strong fire resistance and many other advantages.It is an energy-saving wall material worthy of development and promotion.In this thesis,a high performance foamed concrete with compressive strength up to 5 MPa and thermal conductivity as low as 0.143 W/?m·K?is prepared,which is used to produce assembled foamed concrete filled wallboard.And the trial production of 150-mm-thick wallboard which meets the requirement of 65%energy saving rate in summer hot and winter cold areas was completed.The wallboard with many advantages combines heat preservation and enclosure structure together,overcoming the shortcomings of traditional wall insulation forms and their construction.In this thesis,the durability of the wallboard was tested and researched from four aspects:impermeability,freezing resistance,shrinkage and carbonization,which aims to provide reference for the application and improvement of the wallboard in practical engineering.The main contents and conclusions are as follows:?1?The impermeability of the wallboard was researched.The impermeability of the wallboard is characterized by the descending height of water surface and water absorption.The descending height of water surface of the wallboard is 3 mm.It can be used as a reference for the compilation of enterprise regulations.The water absorption rate of mass and volume is 17.2%and 12.6%respectively.The water absorption rate of volume was compared with the index of relevant codes and the results in literatures.The results show that the water absorption rate of the wallboard meets the requirements of most codes for lightweight filling wall material,but there is still room for further improvement.?2?The freezing resistance of the wallboard was researched.The effects of the erosion of NaCl and Na₂SO₄ solutions with mass fractions of 1%,3%and 5%on the freezing resistance of wallboard and the freezing resistance of the wallboard in clear water were researched.The results show that NaCl can increase the freezing damage of the wallboard,Na₂SO₄ can reduce the freezing damage,and the higher the salt concentration,the smaller the freezing damage of the wallboard.The maximum freeze-thaw cycles that the wallboard can bear with clear water medium is 25,which meets the current codes for lightweight walboard material.And according to block codes,the wallboard can be used in hot summer and cold winter areas besides hot summer and warm winter areas.?3?The drying shrinkage of the wallboard was researched.The equilibrium drying shrinkage rate of the wallboard is 1.18m m/m in the environment of relative humidity?55±5?%and temperature?20±1?°C.It can not meet the requirements of the current relevant lightweight wallboard codes.However,compared with the results in relevant literatures,the drying shrinkage of the wallboard is not bad.The drying shrinkage rate of foamed concrete is generally large and the suggested way to prevent wallboard from drying shrinkage cracking is surface treatment of the wallboard.?4?The carbonization of the wallboard was researched.The carbonization coefficient of the wallboard is 1.19,which is much better than 0.85 or 0.8 given in the codes for lightweight filling materials.It means that carbonization is beneficial to the compressive strength of the wallboard,and the adverse effect of carbonization on the wallboard can only be considered in terms of carbonization shrinkage and alkalinity reduction.