COURSE OF TEMPERATURE IN STRUCTURAL LIGHTWEIGHT CONCRETES DURING HARDENING

TEMPERATURENTWICKLUNG IN KONSTRUKTIONSLEICHTBETONEN WAEHREND DER ERHAERTUNG

HIGHER INCREASES IN TEMPERATURE ARE TO BE EXPECTED FROM THE HEAT OF HYDRATION IN LIGHTWEIGHT CONCRETE THAN FOR NORMAL CONCRETE DUE TO ITS LOWER GROSS DENSITY AND THEREFORE LOWER HEAT CAPACITY AND CONDUCTANCE. IN ORDER TO FIND OUT HOW FAR THE ENFORCED STRAINS AND CRACK FORMATION ARE UNFAVOURABLY AFFECTED THE TEMPERATURE CURVES AND THE ENFORCED STRAINS HAVE BEEN ESTABLISHED FOR TWO LIGHTWEIGHT CONCRETES (AGGREGATE: EXPANDED SLATE OR CLAY) SHORTENING OF THE COOLING PERIOD BEING PREVENTED. FOR COMPARISON, THE SAME TYPE OF TEST SPECIMENS OF NORMAL CONCRETE WERE EXAMINED UNDER THE SAME TEMPERATURE AND STORAGE CONDITIONS. EVALUATION OF THE TEST RESULTS SHOWED THAT WITH UNHINDERED DEFORMATION IN THE CASE OF LIGHTWEIGHT CONCRETE, DESPITE THE HIGHER TEMPERATURE INCREASES, THERE WAS NO INCREASED TENDENCY TO CRACK COMPARED WITH NORMAL CONCRETE. WITH COMPLETE PREVENTION OF DEFORMATION IN THE CASE OF LIGHTWEIGHT CONCRETES A GREATER DROP IN TEMPERATURE WAS REQUIRED FOR CRACK FORMATION THAN WITH NORMAL CONCRETE.