Experimental Study On Temperature Sensitivity Of Polymer Modified Concrete

Properties of freeze-thaw resistance,corrosion resistance,impermeability,bonding performance,and the cohesiveness of new and old interfaces of polymer modified concrete(PMC)outperformed the ordinary concrete due to its specific physical properties and microscope structure.Higher than ordinary concrete.In addition,some types of PMC have higher compressive strength than ordinary concrete.Therefore PMC is a very good structural fabrication and repair material.However,the basic mechanical properties of PMC have a very high sensitivity to ambient temperature.Therefore,this paper deeply studies the internal relationship between PMC and ambient temperature,and provides a theoretical basis for the construction and design of PMC in cold regions.In this paper,the temperature-sensitive properties of PMC in freeze-thaw cycle environments in the cold regions of northern China are studied.The main research work in this paper is as follows:(1)Through the temperature sensitivity test of polyacrylate modified concrete and styrene-butadiene emulsion modified concrete,it was found that polyacrylate modified concrete has obvious temperature sensitivity.Experiments show that polyacrylate modified concrete has obvious temperature sensitivity,while ordinary concrete and styrene-butadiene emulsion modified concrete have no temperature sensitivity in the basic mechanical properties at the ambient temperature set during the test.(2)The change of mechanical properties of polyacrylate modified concrete with ambient temperature was studied.It was found that under non-cyclic conditions,the compressive performance of polyacrylate modified concrete is inversely proportional to the ambient temperature,and the higher the poly-ash ratio,the lower The faster,the stronger the temperature sensitivity.The peak strain of polyacrylate modified concrete is proportional to the ambient temperature.(3)Through the laboratory rapid freeze-thaw test,it was found that the damage evolution law of PMC under dry-freeze cycle conditions.The aging damage evolution law of PMC under dry-freezing conditions is directly proportional to the number of cycles N,and the aging damage value does not exceed its own maximum aging damage value.Under water-freeze cycling conditions,it was found that the freeze-thaw resistance of polyacrylate-modified concrete and styrene-butadiene emulsion-modified concrete was generally higher than that of ordinary concrete.The freezing resistance of PMCs with 7 kinds of mixing ratios were compared,and the optimal mixing ratio of polymer emulsion was obtained.The specific data is: the poly-ash ratio of styrene-butadiene-styrene-modified concrete and polyacrylate-modified concrete is The freeze-thaw resistance is the strongest at 0.10.In this paper,PMC freeze-thaw cycle damage is divided into aging damage of polymer due to temperature change and damage of overall PMC specimen by pore water frost heaving force.The evolution of the two damages is quantitatively analyzed,and a high degree of fitting is derived.Model of PMC freeze-thaw damage evolution.(4)The microstructures of polyacrylate-modified concrete and styrene-butadiene emulsion-modified concrete were observed with the help of scanning electron microscope.The micro-mechanical analysis of the temperature-sensitive mechanism of PMC and the reason why the freeze-thaw resistance is higher than that of ordinary concrete.The main reason that PMC has temperature sensitivity is that the fiber network polymer in PMC has strong temperature sensitivity.There are two main reasons why PMC's freeze-thaw resistance is higher than that of ordinary concrete.First,the polymer used for cement modification forms a continuous fiber network membrane structure inside the concrete matrix.When the free water inside the pores of the matrix rises,the concrete matrix cracks At the same time,the continuous fiber mesh structure can prevent the development of micro cracks in the concrete.Second,the polymer used for cement modification forms fibrous polymer flocks on the inner wall of concrete pores.The structure of such flocks changes the hydrophilicity of the inner wall of concrete pores,repairs inherent defects of concrete,and improves the freeze-thaw resistance of concrete.On the other hand,these flocculent polymers can isolate the pore water from the concrete matrix,and can also consume the energy generated by the frost heaving force by its own deformation when the ambient temperature decreases and the frost heaving force is generated.