RECIPE FOR DURABILITY IN CONCRETE PILE MIXES

This article is concerned with the durability and permeability of cast-in-place concrete piles when produced by the addition of extra sand and water to the mix in order to achieve better flowing properties. This method has been popular because problems arise if standard structural concrete is used, and because it makes use of the contractors specialized knowledge. The extra sand increases cohesiveness and the extra water improves workability. The author briefly discusses the effect of the increase in water/cement ratio on permeability, quoting an 8 to 9-fold increase in permeability with an increase in water/cement ratio from 0.55 to 0.70, and refers to the problems that arise if the cement content is increased to overcome the problem. Attention is drawn to the need for placement under still groundwater conditions; which requires mixes and methods appropriate to placement under water. Problems associated with aggregate are next dealt with, the high sand content making the mix particularly susceptible to sand with a high silt content. Reference is also made to the harsh mixes and slow curing that result from the use of sulphate resisting cement. The visible results of highly permeable concrete and the problem of deciding whether the pile is satisfactory are discussed. It is recommended that groundwater samples be taken at the commencement of the piling contract when there might be a need to study its effect on porous concrete. It is concluded that there is a case for the use of waterproofing agents in piling mixes rather than the use of extra sand and cement which might not always produce the intended effect. /TRRL/

  • Availability:
  • Corporate Authors:

    IPC Building and Contract Journals Limited

    32 Southwark Bridge Road
    London SE1 9EX,   England 
  • Authors:
    • Curtis, R J
  • Publication Date: 1975-7-17

Media Info

  • Features: Photos;
  • Pagination: p. 24-25
  • Serial:
    • CONTRACT JOURNAL
    • Volume: 266
    • Issue Number: 5002
    • Publisher: Reed Business Information, Limited
    • ISSN: 0010-7859

Subject/Index Terms

Filing Info

  • Accession Number: 00129561
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Apr 7 1976 12:00AM