INFLUENCE OF DIFFERENT COOLING MODE AND HIGH TEMPERATUＲE ON CONCRETE SPLITTING TENSILE STRENGTH

Under high temperature，mechanical properties of the concrete structure，especially the tensile strength， would be seriously deteriorated in fire fighting． In order to study the effect of different temperature and cooling mode on splitting tensile strength of concrete materials，the common commercial concrete C35 specimens were heated at high temperature，300，600，800 ℃ respectively． Then，the rule and the cause of the physical and chemical change of these specimens were observed and analyzed with water cooling and natural cooling respectively． Finally keeping the specimens for more than 3 weeks，and the Brazilian disc splitting test was carried out． The result showed that the water cooling and high temperature greatly affected the physical and chemical feature of the concrete specimen also and their splitting tensile strength，and as the temperature increased，the effect of water cooling was more obvious than natural cooling． Mainly in the temperature of over 300 ℃，the decline degree of the tensile strength of specimens caused by water cooling was obviously larger than natural cooling． Based on the test result，the temperature and cooling damage equation was constituted，and the corresponding feature parameter was determined．