Dynamic Splitting Behavior Of Steel Fiber Ceramic Aggregate Concrete At High Temperature

As one of the main disasters that threaten social development,fire can cause great damage to concrete buildings.Based on the use of ceramic aggregate and aluminate cement to enhance resistance to high temperatures,this article proposes a new type of concrete suitable for hightemperature environments: steel fiber-ceramic aggregate concrete,which further increases tensile strength through the addition of steel fibers.This type of concrete can effectively improve the stability of concrete structures after a fire,reducing personal injury and property losses.In sites affected by fires,in addition to static loads,buildings may also be subjected to dynamic impact loads caused by gas explosions and heavy object falls.Under dynamic loads,concrete material produces both compressive and tensile stresses.However,as a brittle material with low tensile strength and small deformation,concrete itself is likely to be damaged because of tension.Therefore,the tensile strength of concrete after high temperatures can be used as one of the indicators for testing the performance of concrete under hightemperature conditions.Hence,studying the dynamic splitting performance of steel fiber ceramic aggregate concrete after high temperatures is of significant importance.In this paper,natural macadam concrete specimens were used as the control group to compare the tensile strength and failure modes of two kinds of concrete specimens(natural macadam concrete specimens and steel fiber ceramic aggregate concrete specimens)after hightemperature heating in static and dynamic splitting tests.The influence of force loading rate and temperature on the tensile strength of the two kinds of concrete was analyzed.The results show that in the static and dynamic splitting tests,the final failure modes of natural crushed stone concrete and steel fiber ceramic aggregate concrete specimens after high temperature are divided into two types: fracture failure and crack without opening.With the increase of the loading rate,the splitting tensile strength of natural crushed stone concrete specimen and steel fiber ceramic aggregate concrete specimen increases at high temperatures,and there is an obvious force loading rate effect.After experiencing high-temperature heating and natural cooling at 1000℃,the natural gravel soil specimen fails directly and loses its bearing capacity,while the steel fiber ceramic aggregate concrete retains 28% of its normal temperature tensile strength in static tensile tests and 20-30% of its normal temperature tensile strength in dynamic tensile tests.This shows the superior high-temperature resistance of steel fiber ceramic aggregate concrete.Based on the test data,the dynamic splitting failure criteria of two kinds of concrete specimens at different temperatures and loading rates are obtained.