Experimental Research On Mechanical Properties Of Thermal Insulation Concrete Under The Freeze-thaw Action And Carbonization

Glazed hollow beads thermal insulation concret is a new type concrete material that adapts to the development of China’s building energy conservation and structural self-insulation system.Its properties achieve the aim that it combines common concrete compressive strength with the low thermal conductivity coefficient of thermal insulation material.Experimental research and pilot project show that thermal insulation concrete is a good measure to realize the structural self-insulation.As the main aspects of the study on the durability,researches on the characteristics and changing mechanism of mechanical properties of thermal insulation concrete under the action of freeze-thaw and carbonization have not been involved in.The test researches and analysis on basic mechanical properties of concrete under the action of freeze-thaw and carbonization will be studied with the consideration of using conditions of thermal insulation concrete under the severe cold of the North and cold climate characteristics.The major works are as follows:1.Experimental study on basic mechanical properties of thermal insulation concret.This paper designs orthogonal experiment with consideration into multiple parameters,will carry out the experiments on mechanical properties of thermal insulation concrete under different mixture ratio,and makes sure four strength indicators including cube compressive strength,axial compressive strength,splitting tensile strength and flexural strength.It will reveal the influence law of various parameters on the basic mechanical properties of thermal insulation concrete through experiments,and sum up the quantitative relationship between various strength indexes and cube compressive strength of concrete by ueing regression method.2.The experimental study on mechanical properties of thermal insulation concrete under the freeze-thaw action.It carries out a total of 0,25,50,75 freeze-thaw cycling tests on thermal insulation concrete by using fast freezing method,and measures the mass loss and relative dynamic modulus of elasticity under different freeze-thaw times,and carries out comparative analysis with the ordinary concrete in order to assess their frost resistance.Under different freeze-thaw cycles,the mechanical properties tests on thermal insulation concrete will be researched,in order to determine the reduction about concrete specimens of each intensity value under different freeze-thaw cycles,and reveal the degradation rule of mechanical properties of concrete under freezing-thawing action.Test analysis shows that:comparing with ordinary concrete,the mass loss rate of thermal insulation concrete is basically the same in this setting freeze-thaw cycles,but the relative dynamic modulus of elasticity improves 8.1%～19.3%.It displays that the internal damage of thermal insulation concrete is slight than ordinary concrete under freezing-thawing action;Under the freeze-thaw action,four strength values down to 60%of original strength are respectively 116,81,59,81.Similar to the ordinary concrete,the strength degradation of thermal insulation concrete under freeze-thaw action is very serious.So the effect of strength degradation should be fully taken into account in durability design.3.The experimental study on mechanical properties of thermal insulation concrete under the carbonation action.This paper carries out the carbonation tests of thermal insulation concrete and ordinary concrete under three different carbonated ages of 7d,14d and 28d.It will determine the depth of carbonation in different ages,and get carbonation depth values of two kinds of concrete and carbonation age,then analyses the carbonation resistance of thermal insulation concrete through comparison.Tests show that:under the same carbonization time,carbonation depth of thermal insulation concrete is 3.7 mm～8.4 mm smaller than ordinary concrete,and displaies the effects of carbonation on thermal insulation concrete is less than ordinary concrete.It carries out strength tests of thermal insulation concrete under different carbonization age,and observes the failure mode of specimens,sums up and analyses curves and formulas on four strength values of thermal insulation concrete specimens growth range with carbonization time,then reveales the evolutionary laws of mechanical properties of concrete under the action of carbonization.4.The experimental study on mechanical properties of thermal insulation concrete under the coupling effect.This paper carryies out tests under different freeze-thaw cycles on thermal insulation concrete specimens after 28d carbonization,carries out tests of basic mechanical properties on thermal insulation concrete specimens after freeze-thawing effect,observes freezing-thawing damage mode of concrete after carbonation,analyses the carbonization effect on frost resistance,then reveals degradation law of concrete after carbonation strength values under the freeze-thaw action.Test results show that:compareing with specimens without carbonation,the cube compressive strength,axial compressive,splitting tensile strength,flexural strength loss rates of carbonation specimens decrease 1.1%～3.5%under the setting freezing-thawing cycles,and displays that carbonation reduces the frost resistance of thermal insulation concrete.The mechanical properties of thermal insulation concrete under the action of freeze-thaw and carbonization that obtained from tests will put forward a reliable theoretical reference for the promotion and application of glazed hollow beads thermal insulation concret.