OPTIMIZING A RETARDER FOR RSZ 400 (PERLMOOSER RAPID HARDENING CEMENT): WORKING OUT OF MIX DESIGN DIAGRAMS AND VERIFICATION OF THESE DIAGRAMS IN PRACTICE

OPTIMIERUNG EINES VERZOEGERERS FUER PSZ 400 (PERLMOOSER SCHNELLZEMENT): AUSARBEITUNG VON DOSIERUNGSDIAGRAMMEN SOWIE VERIFIZIERUNG DIESER DIAGRAMME IN DER PRAXIS

PERLMOOSER RAPID HARDENING CEMENT (PSZ 400) HAS AN EXTREMELY SHORT SETTING TIME AND HIGH EARLY STRENGTH BECAUSE OF ITS SPECIAL CHEMICAL COMPOSITION. THE EARLY STRENGTH MAKES THE CEMENT INTERESTING FOR CONCRETE ROAD CONSTRUCTION, PARTICULARLY FOR REPAIRS, BECAUSE THE ROAD CAN BE OPENED TO TRAFFIC IN A VERY SHORT TIME. HOWEVER, THE CONCRETE CANNOT BE USED IN THIS WAY BECAUSE OF THE VERY SHORT PROCESSING TIME - OFTEN LESS THAN 10 MINUTES. CONVENTIONAL RETARDERS ARE NOT SUCCESSFUL BECAUSE OF THE NEW CHEMISTRY OF THE PSZ 400. ALTHOUGH THERE ARE RETARDERS AVAILABLE FOR THIS CEMENT EXPERIENCE WITH THEM HAS BEEN VERY LIMITED, AND THERE ARE NO MIX DESIGN SPECIFICATIONS. THE OBJECT OF THE RESEARCH IS TO OPTIMIZE THE RETARDER ITSELF, BY MEASURING THE SETTING TIME OF THE CONCRETE WITH VARIOUS WATER CEMENT RATIOS, AND TO ESTABLISH THE RETARDATION IN RELATION TO PROPORTIONING.