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:
  Admixtures Aggregates Concrete Mixing Drums (Containers) Durability Mechanical Properties Ready Mixed Concrete Specifications Workability
• 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.
  
  
• Format:
  PDF
• Funding:
  GCA 6766
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:e7e26fa3960c8f643f8cf75a32e88ffd1e66818eb2af7252ce63447b136f3e7cddc5a0620c4d54c5febc494e47f1ecac2df19cd195d956637777e2b6fa8cfd0f
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/28842/dot_28842_DS1.pdf
• File Type:
  [PDF - 3.09 MB ]