APPARATUS FOR STUDYING CRACKS IN CONCRETE

APPAREIL D'ETUDE DE LA FISSURATION DU BETON

IN ORDER TO OBTAIN A BETTER KNOWLEDGE OF CRACKING A DEVICE WAS DEVELOPED TO PRODUCE FAIRLY RAPIDLY CRACKS IN CONCRETE, THE EXISTING METHOD DEALING WITH PURE PASTE ONLY. THIS NEW FISSURATION TEST CONSISTS IN MAINTAINING A PRISMATIC CONCRETE SAMPLE AT A CONSTANT LENGTH FROM THE TIME THE SAMPLE IS MADE. IF THE SAMPLE SHRINKS, IT IS SUBJECTED TO TENSILE STRESSES, IF IT SWELLS TO COMPRESSION STRESSES. THE DEVICE CONSISTS MAINLY OF A SMALL PNEUMATIC TENSILE MACHINE TO WHICH A MOULDING DEVICE IS ATTACHED. THE ANCHORAGE HEADS ARE LOCATED AT THE EXTREMITIES OF THE DEVICE ONE BEING FIXED TO THE FRAME, THE OTHER BEING MOBILE AND CONNECTED TO THE JACK BY MEANS OF A STRAIN GAUGE DYNAMOMETER. A SYNTHETIC RESIN CONTAINING AN ADEQUATE AMOUNT OF LIMESTONE FIBRES GLUES THE FRESH CONCRETE DIRECTLY ON THE STEEL ANCHORAGE HEADS. AN ELECTRONIC SYSTEM PERMANENTLY MONITORS THE LENGTH OF THE SAMPLE AND REGULATES THE TENSILE DEVICE WHEN NECESSARY. THIS METHOD FACILITATES THE OBSERVATION OF THE BEHAVIOUR OF CONCRETE UNDER THE MAIN PARAMETERS GOVERNING ITS SHRINKAGE AND APTITUDE TO CRACKING. THE FIRST RESULTS OBTAINED SHOW THAT: (1) A SATISFACTORY CORRELATION EXISTS BETWEEN THE TIME OF FISSURATION OF PURE PASTE AND THE FISSURATION TIME OF CONCRETE TAKEN OUT OF ITS MOULD WHEN YOUNG (10 HOURS); (2) FISSURATION TIME OF CONCRETE INCREASES WITH THE AGE OF CONCRETE AT THE TIME IT IS TAKEN OUT OF THE MOULD, WITH TENSILE STRENGTH AND WITH MAXIMUM SWELLING STRESSES. FURTHER RESEARCH IS BEING CONDUCTED WITH THIS DEVICE AT THE LCPC.

  • Availability:
  • Authors:
    • PAILLERE, A M
    • SERRANO, J J
  • Publication Date: 1976-5

Language

  • French

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 01296771
  • Record Type: Publication
  • Source Agency: Institut Francais des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)
  • Files: ITRD
  • Created Date: Nov 21 2010 6:04AM