Experimental Study On The Anti-destructive Performance Of High Performance Concrete At High Temperature

High performance concrete has comprehensive advantages such as high durability,high workability,and high volume stability.It has been widely used and studied in building materials,water conservancy and hydropower,and national defense projects.In the process of work,it is subject to abnormal environmental effects such as static load,impact dynamic load,and high temperature,and different strength grades of high performance concrete have different damage characteristics under the above-mentioned effects.Compared with ordinary concrete,high-performance concrete has unique advantages: high density,low permeability,etc.,but also has disadvantages: large brittleness,poor fire resistance,and once a fire or other extreme event occurs,its structure is easily destroyed and deformed.Cracking,even bursting,flaking and other adverse phenomena,bearing capacity and integrity of the great damage,so that the building collapsed,so that people's lives,property safety is a great threat.Therefore,the degradation,failure and mechanical properties of high performance concrete at high temperature have become the focus of attention in the related field.So far,due to the incompleteness of high-performance concrete production,high-temperature heating and related mechanics experimental techniques,and high-temperature SHPB technology,people's understanding of the destructiveness of high-performance concrete under high temperature has been restricted.Focusing on this topic,this paper has done the following researches on the dynamic and static characteristics of high-performance concrete at high temperature for three different strength grades: C30,C40,and C50.1.Using uniaxial compression and tensile tests at room temperature for ordinary concrete and high performance concrete,analyze the performance gaps between high-performance concrete and ordinary concrete,and the compressive strength,elastic modulus,and stress-strain curves for high-performance concrete.And the relationship between different strength levels;in the process of heating and high temperature of high performance concrete,the physical and chemical changes of high performance concrete and the compressive strength of high strength concrete with different strength levels after high temperature are studied with temperature gradient,heating rate and constant temperature time The law of change between.2.Based on the existing SHPB experimental device in the school,a high-performance concrete dynamic impact test at high temperature was conducted through a resistance furnace heating test piece to study different grades of highperformance concrete,temperature gradient and dynamic compressive strength,strain rate and elastic modulus.The relationship between the other,analysis of high-performance concrete strain rate with temperature changes.3.Propose the damage ratio of high performance concrete at high temperature,and reveal the degradation mechanism of static and dynamic mechanical properties of medium and low strength grades of high-performance concrete with temperature change,so as to deeply understand its anti-destructive performance at high temperature.