LABORATORY INVESTIGATION OF SLIPFORM CONSTRUCTION FOR USE IN MASS CONCRETE STRUCTURES

A laboratory investigation was conducted to study applications of the slipforming technique in mass concrete construction. Opposite sides of large blocks were slipformed in a specially fabricated test frame using mass concrete mixtures. Variables included casting temperature, type and maximum size of aggregate, use of a lubricating admixture, slipping rate, type of form anchors, and type of slipform surface. Based on the results of this study the following conclusions appear warranted: The slipforming technique appears feasible for use in mass concrete construction. Esthetically, the appearance of slipformed concrete should be similar to that of conventionally placed concrete. No discernible effects of type of aggregate, whether natural or crushed stone, or of maximum size of aggregate, whether 3 or 6 in. were noted. The maximum feasible slipping rate determined for the variables in this study (mass concrete, concrete temperature of 60 F (15.5 C), and 4-ft (1.2-m) height of slip form) was found to be 18 in./hr (457.2 mm/hr). A minimum of 6 in./hr (152.4 mm/hr) is recommended. However, rates less than 6 in./hr may be satisfactory if consideration is given for avoidance of cold joints. Steel-lined slip forms appear to be superior to tongue and groove lumber and impregnated plywood slip forms for use in mass concrete slipforming. Form lifting pressures are likely to be approximately twice those for structural concrete (250 versus 125 lb per linear foot (3648.5 versus 1824.2 N per linear metre) of form). The use of a lubricating admixture reduced drag pressures by about 50 lb per linear foot (729.7 N per linear metre) of form width. A shear-plate type of form anchor offers good strength for use in design of a form-support apparatus. A definitive method of determining the degree of hardening as related to slip rate was not determined. The method normally used for structural slipforming, i.e., forcefully jamming a rod down to the hardened concrete, does not appear practical for use with mass concrete. Temperature measurements in the laboratory blocks indicated that peak slipform temperatures did not exceed those that were calculated for conventionally placed 5-ft (1.5-m) layers in the same block. However, other calculations, for larger structures, indicate that slipforming should result in higher peak temperatures than would be attained using conventional 5-ft layers. /Author/

  • Corporate Authors:

    U.S. Army Waterways Experiment Station

    3909 Halls Ferry Road
    Vicksburg, MS  USA  39180-6199
  • Authors:
    • Saucier, K L
  • Publication Date: 1974-7

Media Info

  • Features: Appendices; Figures; References; Tables;
  • Pagination: 79 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00165498
  • Record Type: Publication
  • Report/Paper Numbers: Tech. Rpt. C-74-3
  • Files: TRIS
  • Created Date: Jan 13 1978 12:00AM