Variability in Fresh Concrete Properties as Observed in NHI Highway Materials Engineering Course

An integral component of the PCC module of the annual NHI Highway Materials Short Course is a series of independent and parallel evaluations of fresh and hardened properties for a single load of concrete. Six testing teams independently sample concrete from the truck and test the fresh concrete for temperature, slump, unit weight, and air content by pressure and by volume meter. Air temperature, wind speed, and humidity are also recorded for subsequent estimation of evaporation rate. The experiment has been repeated annually since its inception in 1990, with the objectives of demonstrating test procedures and the effect of various procedural factors on test results, showing by example the inherent variability in test results when the concrete itself is all from a single load; and in the case of fresh concrete, showing how results vary systematically with time after batching. This paper addresses only fresh concrete properties, showing the uncertainty and in particular the time-dependency in both slump and apparent air content. The relationship between slump and apparent air content, and the difference between air content as indicated by the AASHTO T152/ASTM C231 pressure air meter and the AASHTO T196/ASTM C173 volumetric air meter is also demonstrated.

Language

  • English

Media Info

  • Media Type: DVD
  • Features: Figures; References; Tables;
  • Pagination: 25p
  • Monograph Title: TRB 89th Annual Meeting Compendium of Papers DVD

Subject/Index Terms

Filing Info

  • Accession Number: 01155548
  • Record Type: Publication
  • Report/Paper Numbers: 10-3835
  • Files: TRIS, TRB
  • Created Date: Jan 25 2010 11:57AM