Experimental Study On Bond Performance Between Steel And Polymer Cement Mortar After High Temperature

Polymer cement mortar(PCM)is widely used in the reinforcement of reinforced concrete structures due to its excellent mechanical properties,durability and good adhesion to concrete.At present,there have been many studies on the bonding properties of PCM and concrete under different conditions,but there are few studies on the bonding properties of PCM and reinforcing steel,especially after the fire and high temperature.This paper studies the mechanical properties of PCM after high temperature and the bond properties of reinforced PCM through high temperature PCM mechanical properties test and reinforced PCM center pull test,The main work contents are as follows:(1)Mechanical performance test of PCM after high temperature.Through the experimental research on the flexural strength and compressive strength of 78 flexural specimens and 117 compressive specimens after high temperature under different cooling methods,the flexural performance and resistance of PCM to different temperatures and different cooling methods were analyzed.The impact of compressive properties was compared with the flexural and compressive properties of PCM and concrete under two conditions,and the PCM compressive and compressive strength degradation model was established after two high-temperature cooling methods.The research results show that:after high temperature,the flexural and compressive properties of PCM generally decrease with the increase of temperature;the flexural and compressive strength of PCM specimens cooled by water after about 300℃ is higher than that of natural cooling Compared with concrete specimens,the flexural strength and compressive strength of PCM specimens are higher than those of concrete specimens.(2)Bonding performance test of reinforced bar PCM after high temperature.Through the central pull test on 72 bonded specimens,the effects of different temperatures,different steel bar diameters,and different cooling methods on the bonding performance of reinforced PCM were studied.The degradation model of steel bar PCM bond strength after two cooling methods at high temperature is presented.The research results show that: after the same diameter and the same cooling method,the ultimate bond strength of the steel bar PCM generally decreases with increasing temperature,while the ultimate bond slip of the specimen decreases first with increasing temperature.After the same temperature and the same cooling method,the ultimate bond strength of the test piecedecreases with the increase of the diameter,and the ultimate bond slip corresponding to the ultimate bond strength is inversely proportional to the diameter;the same temperature and At the same diameter,the ultimate bond strength of the specimen after natural cooling is higher than that of the water-cooled specimen,and the ultimate slip of the specimen after the water-cooling is higher than that of the specimen after natural cooling;compared with ordinary reinforced concrete,The ultimate bond strength of reinforced PCM is lower than ordinary reinforced concrete,but the ultimate bond slip is higher than ordinary reinforced concrete.(3)PCM bond-slip relationship curve of steel bar after high temperature.Through the actual test data,the PCM bond slip curves of steel bars with different temperatures,different cooling methods,and different steel bar diameters are fitted,and the corresponding bond slip calculation formula is given.