STUDY OF THE CHARACTERISTICS OF CONCRETE SUBJECTED TO MODERATE TEMPERATURES

A STUDY WAS CONDUCTED OF THE MECHANICAL AND THERMAL CHARACTERISTICS OF CONCRETE SUBJECTED TO MODERATE TEMPERATURES (-10 DEG C AND 80 DEG C), CONDITIONS TO WHICH CONCRETE STRUCTURES CAN BE SUBJECTED IN TEMPERATE CLIMATE. THE VARIATION IN THE THREE MECHANICAL CHARACTERISTICS STUDIED (COMPRESSION, SPLITTING AND ELASTIC MODULUS) WAS SHOWN TO ALTER REGULARLY WITH THE TEMPERATURE WITHOUT ANY MARKED DIFFERENCES IN THE 7 MIX DESIGNS USED, IN RELATION TO THE PERFORMANCES OBTAINED AT 20 DEG C. THE MECHANICAL PROPERTIES INCREASE WHEN THE TEST IS CONDUCTED AT A TEMPERATURE LOWER THAN 20 DEG C BUT THEY DECREASE SLIGHTLY WHEN THE TEMPERATURE INCREASES UP TO 80 DEG C. THE MASS HEAT OF THE CONCRETE SEEMS TO BE INDEPENDENT OF THE TYPE OF CONCRETE AND IS OF THE ORDER OF 0,2 KCAL/KG PER DEGREE C. USING THE RESULTS OF TESTS ON 3 OF THE 7 TYPES OF MIX DESIGN WITH 2 TEST METHODS SELECTED, IT APPEARS THAT THE THERMAL CONDUCTIVITY OF CONCRETE TO THE SURROUNDING TEMPERATURE IS IN FACT HIGHER THAN THE HEAT NORMALLY USED IN PRACTICE.