Experimental Study On The Durability Of New Inorganic Cementitious Materials And Their Composite Bamboo

As the non-renewable natural mining resources are increasingly exhausted,the state vigorously advocates the development of bamboo and wood green buildings.Bamboo and wood building is the main structural form of traditional buildings in China,which has the advantages of renewable,high strength-weight ratio,light earthquake resistance and integration of structural decoration.The development of bamboo and wood structure will become an important direction of sustainable development of civil engineering.China's timber resources are relatively scarce,but bamboo resources are quite abundant.Bamboo has the advantages of short growth cycle,good mechanical properties and energy conservation and environmental protection.In recent years,with the maturity of bamboo processing technology,various kinds of composite materials with bamboo as raw materials develop rapidly.The material used in this paper is based on the new inorganic composite bamboo developed by the research group,and the durability of the new inorganic cementing material and its composite bamboo are studied respectively.The water resistance of the new inorganic cementite material and inorganic composite bamboo was studied.The strength residual value of the specimens after soaking for different days was measured,and the mechanism was analyzed by means of apparent properties,XRD and electron microscopy.It was found that soaking had a greater effect on the inorganic cementite material than bamboo bundle.The morphology of the matrix changes from dense needle-rod crystal to loose,and porosity increases,leading to softening of the material.The results show that the water resistance of inorganic composite bamboo is in the following order:tensile softening coefficient > bending softening coefficient > compression softening coefficient.The minimum compression softening coefficient is 0.68.The study on the drying and wetting cycles of new inorganic cementitious materials and inorganic composite bamboo,combined with the analysis of the strength test data by means of apparent properties,XRD and electron microscopy,found that the drying and wetting cycles of inorganic cementitious materials produce shrinkage cracks and reduce the integrity of inorganic composite bamboo.Due to the existence of bamboo bundle,the dry-wet cycling performance of inorganic composite bamboo is better than that of inorganic cementitious material.For inorganic composite bamboo,the tensile specimen has the best performance,and the corrosion resistance coefficient is 0.66 after 30 cycles of wetting and drying.The compressive strength has the greatest influence,and the corrosion resistance coefficient is 0.54 after 30 cycles of wetting and drying.By analyzing the quality of the new type of inorganic composite bamboo after freezing and thawing cycle loss rate and relative dynamic elastic modulus,combined with the apparent damage,obtained due to the surface pore and as you progress through the freeze-thaw cycle and continuous development lead to freezing and thawing cycle damage concentrated in the later period,after a 100-cycle quality loss 3.07%,maximum relative dynamic elastic modulus at28.88%.The test results show that because the material itself has good water resistance and the damage to the varnish is more serious in the later period of dry-wet cycle,the improvement of water resistance and dry-wet cycle performance of the inorganic composite bamboo specimen coated with varnish is limited.In the freezing-thawing cycle test,the apparent phenomenon and the experimental data show that the mass loss rate and dynamic elastic modulus loss rate of inorganic composite bamboo specimens without lacquer and varnish are quite different.Varnish protection improves the freezing-thawing cycle performance of inorganic composite bamboo significantly.