Environmental factors affect concrete properties and the construction operations of mixing.
The American Concrete Institute (ACI, www.concrete.org) relies on the work of over 3,000 volunteers who serve on committees to develop the latest codes and reports related to concrete, including a committee on hot weather concrete practices. The mission of ACI Committee 305 – Hot Weather Concreting is to develop and report information on hot weather concreting. Active documents of ACI Committee 305 – Hot Weather Concreting include 305R-10: Guide to Hot Weather Concreting and 305.1-14: Specification for Hot Weather Concreting.
305R-10: Guide to Hot Weather Concreting describes how “…environmental factors, such as high ambient temperature, low humidity, high wind, or both low humidity and high wind, affect concrete properties and the construction operations of mixing, transporting, and placing of the concrete materials.” Further, 305R-10 provides measures that can be taken to minimize the undesirable effects of these environmental factors and reduce the potential for serious problems.
First, 305R-10 defines hot weather and discuss potential problems associated with the construction operations of mixing, transporting, and placing of concrete materials. Then, 305R-10 presents numerous, best practices and industry standards to help minimize the effects and mitigate the risks of hot weather on construction operations of concrete materials, including but not limited to selecting materials and proportions, precooling ingredients, and batching, for example.
Other topics in 305R-10: Guide to Hot Weather Concreting include “…length of haul, consideration of concrete temperature as placed, facilities for handling concrete at the site, and, during the early curing period, placing and curing techniques, and appropriate testing and inspection procedures in hot weather conditions.” The American Concrete Institute (ACI, www.concrete.org) recommends that the materials, processes, quality control measures, and inspections be tested, monitored, or performed as applicable only by individuals holding the appropriate ACI certifications or equivalent.
Keywords: air entrainment; bleeding; cooling; curing; evaporation; finishing; high temperature; hot weather construction; mixture proportioning; plastic shrinkage; plastic shrinkage cracking; production methods; protection period; retempering; slump tests; trial batch; water content.
(Source: American Concrete Institute, www.concrete.org)
More in the next blog about hot weather concreting…