THE INFLUENCE OF LONG MIXING TIME ON THE PROPERTIES OF CONCRETE

EINFLUSS LANGER RUEHRZEITEN AUF DIE BETONEIGENSCHAFTEN

IN DIN 1045 THE TIME FROM ADDING WATER TO THE COMPLETE EMPTYING OF THE TRANSPORTING DRUM IS LIMITED TO 90 MINUTES, ALTHOUGH VARIOUS INFLUENCES CAN AFFECT THE STIFFENING OF THE CONCRETE. FOLLOWING A SUMMARY OF THE BASIC MATERIAL USED FOR THE COMPREHENSIVE SERIES OF TESTS, THE TESTING PROGRAMME IS DISCUSSED. THE INFLUENCE OF MIXING TIME ON CONSISTENCY, AIR VOIDS CONTENT, SETTING SEQUENCE AND COMPRESSIVE STRENGTH ARE INVESTIGATED SEPARATELY IN ADDITION TO THE INFLUENCE OF WATER CONTENT ADDED FOR RE-ESTABLISHING THE INITIAL CONSISTENCY. IT WAS SHOWN THAT WITH INCREASED CONCRETE TEMPERATURES AND AMBIENT TEMPERATURES THE STIFFENING INCREASED WITH HIGH-GRADE CEMENT AND HIGH CEMENT CONTENTS. IT IS THEREFORE RECOMMENDED TO ADJUST THE CONCRETE STRENGTH DOWNWARDS OR TO ADD A RETARDER. WITH A CONCRETE THAT STIFFENS IN SPITE OF THIS, A LOW WATER ADDITION OF (LESS THAN 10% OF THE REQUIRED MIXING WATER) SHOULD BE TOLERATED, ALTHOUGH WITH THIS A REDUCTION IN COMPRESSION STRENGTH CAN OCCUR. WHERE THERE ARE PROBLEMS WITH PLACING, THE CONCRETE SHOULD NOT BE STORED UNDER DAMP CLOTHS AFTER DEPOSITION FROM THE TRUCK MIXER BUT SHOULD BE MIXED FURTHER.

  • Corporate Authors:

    BetonVerlag GmbH

    Duesseldorfer Strasse 8, Postfach 450
    4 Duesseldorf,   Germany 
  • Authors:
    • Hallauer, O
  • Publication Date: 1978-4

Language

  • German

Media Info

  • Pagination: 131-5
  • Serial:
    • Beton
    • Volume: 28
    • Issue Number: 4
    • Publisher: BetonVerlag GmbH

Subject/Index Terms

Filing Info

  • Accession Number: 01289114
  • Record Type: Publication
  • Source Agency: Forschungsgesellschaft für Straßen- und Verkehrswesen (FGSV)
  • Files: ITRD
  • Created Date: Nov 21 2010 1:38AM