Investigation of the Evolving Relationship Between the Properties of Ordinary Concrete and High Performance Concrete at High Temperatures

Elevated temperature can cause alterations in concrete materials by destroying the hydrated constituents of the cement paste. this destruction involves weakening by degradation of the material’s mechanical properties such as stiffness and strength. as a result of this destruction, material weakening can occur. higher temperature also generates significant fluid pressure which may lead to damage and cause concrete collapse characterized by the deterioration of the hydrated material. the main objective of this experimental study is to focus on the evolution of the residual properties of five ordinary concretes (oc) and three high performance concretes (hpc) and the evolution of the deterioration of hydrated material. the specimens were specimens were (15*15*15) cm³ of ordinary concretes and (16*32) cm² of (hpc) and were subjected to temperatures of (200°c), (400°c), and (600°c) with a rate of (2°c/min) for three hours, followed by cooling at room temperature. the deterioration of various properties was evident compared with a room temperature of (20°c), with a maximum loss of compressive strength of (48%) for the ordinary concrete whereas (79%) for hpc. the loss of tensile strength was (65%) for oc (62%) for hpc. the loss in density and the dynamic modulus elastic were (5%) and (97%) respectively for (oc) and (6%) and (89%) respectively for (hpc). an explosive burst of one (hpc) between (400°c) and (600°c) was observed.