Study On Bonding Performance Test And Reinforcement Measures Of External Insulation Structure Of Glazed Hollow Beads

Compared with other external thermal insulation(ETI)processes,the glazed hollow beads(GHB)external thermal insulation system(ETIS)has the advantages of fire prevention,low thermal conductivity,etc.,and has been widely used in domestic and abroad.However,due to the ETIS cracking,shedding and other engineering diseases in recent years,the research and improvement of ETI technology has become increasingly urgent.This paper adopts the combination of laboratory test and finite element simulation to study the crack morphological characteristics,the deformation discipline and degradation mechanism under the temperature gradient cycling influence of the ETIS made of GHB.The main work and related conclusions are as follows.1.Suitable indoor test schemes were designed.Totally four types of specimens,the standard interface specimens for ETI of GHB and three types of reinforced specimens,were prepared.Besides,the loading device in the laboratory was modified.2.The shear bond performance of four types of GHB external insulation specimens subjected to a series of experimental studies,and the shear failure mechanism,failure plane crack development rule and variation rule of strength influencing factors of the specimens were obtained.The results show that the bond strength of the three types of reinforced specimens is greater than that of the standard interface specimens and the bond strength of the steel netting specimens is the greatest.In terms of influencing factors,the shear bond strength of specimens increases with the thickness of thermal insulation layer.The shear bond strength of standard interfacial specimens increases with the thickness of interface treating mortar,but when the thickness increases to a certain extent,the strength growth rate slows down.The shear bond strength of standard interface specimens increased with the curing days,but the subsequent growth rate tended to be flat.3.The temperature gradient cyclic test and shear bond strength test were carried on four types of specimens,the characteristics of strain fluctuation and strength variation rules of specimens under temperature gradient cyclic load were obtained.The results show that the amplitude of strain fluctuation at the bonding interface tends to decrease,with the increase of the number of cycles.When the types of specimens are the same,the specimens' amplitude of strain fluctuation at the bonding interface is larger,whose thickness of thermal insulation layer is thicker.At the same condition,the fluctuation range of glass fiber specimens in the temperature gradient cycling test is the minimum,while that of steel netting specimens is the maximum.In addition,the shear bond strength of specimens decreases with the increase of cycle times,and the loss rate of strength increases with the cycle times,but the growth rate of strength loss rate gradually slows down with the increase of cycle times.The strength loss rate of the three kinds of reinforced specimens is smaller than that of the standard interface specimens.Among the four types of specimens,the strength loss rate of glass fiber specimens is the smallest,while that of standard interface specimens is the largest.4.The finite element software ANSYS was used to conduct the numerical modeling of the temperature gradient cycling test,carried on standard interface specimens,and the results were compared with the test results.Some results were in good agreement with each other.However,due to objective environment and operational reasons,there were some differences between simulation results and experimental data.