Advances in Cost-Effective Cement Reduction

This paper will discuss how reducing cement usage can cut emissions of greenhouse gasses. However, practical methods of reducing cement in concrete are limited by problems with entrained air. Air entrainment itself reduces concrete strength, and this requires higher cement to compensate. Adding water-reducing admixtures (WRAs) can decrease water, allowing some reduction in cement without reducing strength, and adding fly ash can allow replacement of some cement without reducing strength. However, both WRAs and fly ash can affect air volume in unpredictable ways. Therefore their use may have to be limited if concrete is to stay within specifications. Lastly, general variations in entrained air cause fluctuations in strength. These require the producer to increase average cement dosage to keep strengths safely above requirements. A polymer-based air entrainment system (PBAES) promises to allow more cement reduction by reducing the impact of air entrainment on strength, and by experiencing less variability. The authors tested these effects with data from a ready-mix producer that recently changed its air entrainment to a PBAES. Comparisons of batch data before and after the change confirm that concrete using the PBAES had significantly higher compressive strength and had much lower variability in air volume and concrete strength despite normal variations in raw materials. The differences were great enough that they might safely allow significant reduction in the amounts of cement used.

• Corporate Authors:

  National Ready Mixed Concrete Association

  900 Spring Street
  Silver Spring, MD  United States  20910
• Authors:
  • Zubrod, Rodney W
  • Welker, Charles D
  • VanderWerf, Pieter A
• Conference:
  • Concrete Technology Forum. Focus on Sustainable Development
  • Location: Denver CO, United States
  • Date: 2008-52-0 to 2008-52-2
• Publication Date: 2008

Language

• English

Media Info

• Media Type: CD-ROM
• Features: Appendices; Figures; References; Tables;
• Pagination: 17p
• Monograph Title: Concrete Technology Forum. Focus on Sustainable Development

Subject/Index Terms

• TRT Terms: Air content; Air entraining cement; Cost effectiveness; Fly ash; Greenhouse gases; Pollutants; Water cement ratio; Water reducing agents
• Uncontrolled Terms: Emissions reduction; Reduction (Decrease)
• Subject Areas: Environment; Highways; Materials; I32: Concrete;

Filing Info

• Accession Number: 01159175
• Record Type: Publication
• Files: TRIS
• Created Date: Jun 14 2010 2:55PM