STRENGTH DETERIORATION OF HIGH STRENGTH CONCRETE EXPOSED TO HIGH TEMPERATURE AND ITS PREVENTION AND REHABILITATION

High strength concrete (HSC) has been used in situations where it may be exposed to elevated temperatures. Properties of high strength concrete are deteriorated after concrete is exposed to high temperature. In this study, Strength deterioration of high strength concrete exposed to high temperature and its prevention and rehabilitation are investigated experimentally. Test results show that the compressive strength of both HSC and normal strength concrete (NSC) decreases when the exposed temperature is higher than 200 degrees C. After fly ash are replaced by Red Mud (RM) or Metakaolin (K), deterioration of compressive strength can be reduced, moreover, mixing polypropylene(PP) fiber is also an effective prevention method due to its spalling resistance action. Re-curing in water, sodium silicate/magnesium fluosilicate composition solution (NSF) or aluminum sulfate solution (AS) can rehabilitate compressive strength of HSC exposed to high temperature. In addition, SEM analysis, X-ray diffraction analysis and Mercury injection test are also carried out to analysis microstructure of HSC exposed to high temperature.