HEAT DEVELOPMENT DURING CEMENT HYDRATION

WAERMEENTWICKLUNG BEI DER ZEMENTHYDRATATION

IN THE HARDENING OF CEMENTS, HEAT OF HYDRATION IS PRODUCED WHICH, ACCORDING TO CHARACTERISTICS AND COMPOSITION OF THE CEMENT VARIES IN AMOUNT AND WHICH MAY LEAD TO TEMPERATURE INCREASES IN MASSIVE CONCRETE STRUCTURAL COMPONENTS. THE HEAT OF HYDRATION OF A CEMENT, AMONG OTHER THINGS, IS DETERMINED FROM THE DIFFERENCE OF THE HEATS OF SOLUTION OF THE NON-HYDRATED CEMENT AND THE 20 DEGREES C ISOTHERM FOR HYDRATED CEMENT. TESTS SHOWED THAT THE ACCURACY OF THE DETERMINATION OF THE HEAT OF SOLUTION DEPENDS TO A GREAT EXTENT ON THE WATER CONTENT AND THE WATER BONDING OF THE HYDRATED CEMENT. THE HEAT OF SOLUTION OF THE CEMENT PASTE INCREASES WITH DECREASE IN WATER CONTENT. THE TESTS ALSO PERMIT OF CONCLUSIONS REGARDING THE TYPE OF WATER BONDING IN THE CEMENT PASTE. APART FROM WHETHER THE WATER IN IT IS CHEMICALLY MORE OR LESS TIGHTLY BONDED OR IS ONLY ABSORBED ON THE SURFACE OF THE HYDRATED PHASE, A VARYING INCREASE IN HEAT OF SOLUTION OCCURS WHICH IS HOWEVER CONSTANT FOR THE DIFFERENT DRYING STATES.