INFLUENCE OF HOT-DIP GALVANISING ON THE PROPERTIES OF PRESTRESSING STEELS

UNTERSUCHUNGEN UEBER DEN EINFLUSS DER FEUERVERZINKUNG AUF DIE EIGENSCHAFTEN VON SPANNSTAEHLEN

THE UNIFORMITY, THICKNESS, ADHESION AND CRACKING OF ZINC COATINGS ON COMMERCIALLY GALVANISED PRESTRESSING WIRES AND REINFORCING STEEL MATS WAS EXAMINED. BASIC MECHANICAL COEFFICIENTS WERE DETERMINED ON NON-GALVANISED AND GALVANISED STEELS TO CHECK WHETHER THE STEELS SATISFY THE CONDITIONS OF THE STANDARD. RESULTS SHOWED THAT GALVANISING PRODUCES GOOD QUALITY PRESTRESSING STEELS, BUT THAT THE GALVANISATION OF THE REINFORCING STEEL MATS IS LESS SATISFACTORY BECAUSE OF THE NON-UNIFORM THICKNESS OF THE COATING. DUE TO THE EFFECT OF THE HEAT DURING GALVANISATION, STRENGTH VALUES OF THE PRESTRESSING STEELS ARE SOMEWHAT DIMINISHED; FATIGUE BEHAVIOUR IS EQUALLY GOOD OR BETTER WITH GALVANISED MATERIAL AND RELAXATION BEHAVIOUR REMAINS THE SAME. SIMILAR RESULTS WERE OBTAINED WITH THE REINFORCING STEEL MATS; IN SOME CASES THERE WERE EVEN MORE FAVOURABLE COMBINATIONS OF STRENGTH AND DEFORMATION BEHAVIOUR. THE SHEAR BEHAVIOUR OF WELDED JOINTS IS UNAFFECTED BY GALVANISING, AND FATIGUE BEHAVIOUR IS CONSIDERABLY BETTER.