INFLUENCE OF TEMPERATURE ON THE EFFECTIVENESS OF AIR- ENTRAINING AGENTS

EINFLUSS DER TEMPERATUR AUF DIE WIRKSAMKEIT VON LUFTPORENBILDERN

THE OBJECT OF THE RESEARCH IS TO EXAMINE THE INFLUENCE OF THE ENVIRONMENTAL OR THE CONCRETE TEMPERATURE ON THE EFFECTIVENESS OF AIR-ENTRAINING AGENTS. THE RESULTS OF THE STUDY SHOULD ENABLE THE CONCRETE ENGINEER TO ESTABLISH, FOR VARIOUS CLASSES OF AIR-ENTRAINING AGENTS, THE QUANTITY OF ADMIXTURES REQUIRED TO OBTAIN A DEFINED AIR-ENTRAINED SYSTEM IN RELATION TO THE TEMPERATURE OF THE ENVIRONMENT AND THE CONCRETE. THIS WOULD SIMPLIFY THE MANUFACTURE OF FROST- RESISTANT CONCRETE ON THE CONSTRUCTION SITE. THE STUDIES ARE TO BE CARRIED OUT ON CYLINDRICAL SAMPLES OF CONCRETE FOR ROADS IN ACCORDANCE WITH THE RECOMMENDATIONS TV BETON 72. IT IS PLANNED TO EXAMINE CONCRETE HAVING TWO CEMENTS OF VARYING FINENESS, 2 GRADING CURVES, AND 3 - 4 ADMIXTURES WITH DIFFERENT ORIGINS AND CHEMICAL STRUCTURE. THE TEMPERATURE OF THE FRESH CONCRETE SHOULD BE 5, 10, 20 OR 30 DEGREES C. AS WELL AS THE TOTAL AIR VOID CONTENT AND ALL THE OTHER NECESSARY CHARACTERISTIC VALUES OF THE FRESH CONCRETE, THE CHARACTERIZATION OF THE AIR VOID SYSTEM IN THE HARDENED CEMENT PASTE WILL BE PARTICULARLY OBSERVED. IN ADDITION THE MEASURING LINE METHOD, WHICH HAS BEEN PROVED IN MICROSCOPIC INVESTIGATIONS, WILL BE USED TO DETERMINE VOID SIZE DISTRIBUTION, DISTANCE FACTOR ETC. MOREOVER THE COMPRESSIVE STRENGTH OF THE CONCRETE AFTER 28 DAYS OF NORMAL STORAGE WILL BE DETERMINED AS A REFERENCE VALUE.