RATIONAL DESIGN OF AIR ENTRAINED CONCRETE

The use of concretes of very high workability in conjunction with vibration is usually unsatisfactory because of the associated problems of segregation, bleeding and internal water gain. However, air entrainment can greatly increase the cohesion of concrete, enabling the economic advantages of using very short vibration times to be exploited. Air entrained concrete can now also be pumped economically, with the advent of the modern type of pump. Further, the increasing use of thick structural sections with high cement contents (e.g. massive foundation bases) has resulted in frequent problems from exessive cracking due to heat of hydration effects. Although the reinforcement can and should be designed to control such cracking, these problems can be significantly reduced by using air entrainment. The paper therefore investigates the workability of air entrained concrete and indicates how these concretes may be designed for any vibration time using the local materials which are available. The standard VEBE test is not sufficiently sensitive for very short vibration times and a suitable modified VEBE test has been used. /Author/

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 841-853

Subject/Index Terms

Filing Info

  • Accession Number: 00095495
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Jul 2 1975 12:00AM