Effects of extended discharge time and revolution counts for ready-mixed concrete.

Details

• Creators:
  Trejo, David ; Chen, Jiaming
• Corporate Creators:
  Oregon State University
• Corporate Contributors:
  United States. Federal Highway Administration
• Subject/TRT Terms:
  • Ready mixed concrete
  • Drums (Containers)
  • Specifications
  • Concrete mixing
  • Workability
  • Durability
  • Admixtures
  • Aggregates
  • Mechanical properties
• Publication/ Report Number:
  WA-RD 831.1
• Resource Type:
  Tech Report
• Geographical Coverage:
  Washington
• Corporate Publisher:
  Washington (State). Department of Transportation. Research Office
• Abstract:
  Specifications for ready-mixed concrete limit drum revolution and mixing time to 250 drum revolutions and/or ; 1.5 hours before discharge. These specifications have been in place for many years with the objective of ensuring ; the quality and performance of the finished concrete product; however, these limitations could potentially increase ; construction costs without additional benefits, especially when longer transport distances are required. Because ; there have been significant changes in concrete constituent materials (e.g., chemical admixtures) and equipment ; since these limits were first implemented, research is needed to assess the effects of time to discharge and drum ; revolution counts on concrete performance. The objective of this research program is to evaluate and verify ; whether existing specifications for mixing and transporting concrete are applicable for today’s materials and ; equipment and if not, to identify key variables or tests that can ensure adequate placeability and good mechanical ; and durability characteristics. This study evaluated the influence of coarse and fine aggregate, supplementary ; cementitious materials quantity and type, chemical admixtures, temperature and mixing time and drum revolution ; on the mechanical and durability characteristics of concrete. Results indicate that existing specifications may be ; appropriate due to loss of workability. However, mixing time and drum revolution counts had no significant effects ; on the majority of mechanical properties and durability characteristics of ready-mixed concrete and results from ; this research indicate that existing specification limits are very conservative.
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• Format:
  PDF
• Funding:
  GCA 6766
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/28842/dot_28842_DS1.pdf
• File Type:
  [PDF - 3.09 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:e7e26fa3960c8f643f8cf75a32e88ffd1e66818eb2af7252ce63447b136f3e7cddc5a0620c4d54c5febc494e47f1ecac2df19cd195d956637777e2b6fa8cfd0f