Experimental Study On The Improvement Of Mechanical And Durability Properties Of Concrete By Pumice Sealer Surfacing

In this thesis,a new type of aggregate was prepared by using the open pores of pumice aggregate to adsorb water glass solution and fly ash.The age water absorption,apparent density and cylinder compressive strength of the aggregate were determined,and the light-aggregate concrete was configured based on the volumetric method.The concrete was subjected to cubic compressive test,clear water freeze-thaw cycle test,5%Na2SO4 salt corrosion-freeze-thaw cycle coupling test to study the macroscopic mechanical and durability performance of the concrete,and the microscopic changes inside the concrete were analyzed with the help of micro hardness tester,environmental scanning electron microscope and nuclear magnetic resonance instrument,and the Weibull theory was used to predict the Weibull theory was used to predict the durability performance of concrete.The main research contents and results are as follows.(1)Pumice aggregate sealing treatment can effectively fill the open pores on the surface of pumice,reduce the age-absorption rate of light aggregate,retain more internal cavities for light aggregate,and at the same time enhance the light aggregate to improve the compactness of light aggregate and increase the cylinder compression strength of light aggregate.(2)Through the concrete mechanical test and microscopic test research shows that:the pumice surface sealing material can enhance the strength of the bond between the aggregate and cement stone,enhance the microhardness of the interface zone,make the interface transition zone more dense,the concrete is uniformly stressed,thus improving the cubic compressive strength of concrete,while the "ring hoop effect" in the cubic compressive test "weakened.(3)Through the concrete mechanical test and microscopic test research shows that:the pumice surface sealing material can enhance the strength of the bond between the aggregate and cement stone,enhance the microhardness of the interface zone,make the interface transition zone more dense,the concrete is uniformly stressed,thus improving the cubic compressive strength of concrete,while the "hoop effect" in the cubic compressive test "weakened.(4)Through the light aggregate concrete 5% Na SO4 salt corrosion-freeze-thaw cycle test and microscopic test research shows that: closed pumice pores can improve the lightcaggregate concrete salt corrosion-freeze-thaw cycle durability,concrete salt corrosion-freeze-thaw cycle under the action of the degree of damage than the love letter freeze-thaw,with the relative dynamic Modulus of elasticity index to evaluate the concrete resistance to salt corrosion-freeze-thaw durability is more accurate.The concrete salt-etching-freeze-thaw durability is optimal when the water-glass content in the aggregate pre-wetting solution is 5%.(5)Weibull theory was used to predict the service life of each group of light aggregate concrete for clear water freeze-thaw cycles and salt erosion-freeze-thaw cycles.The results show that the weibull model fits well and can accurately predict the service life of light aggregate concrete in Northwest China.