DETERMINATION OF THE MAXIMUM PLACEMENT AND CURING TEMPERATURES IN MASS CONCRETE TO AVOID DURABILITY PROBLEMS AND DEF

This project investigates the effect of curing temperature on concrete strength, durability and other physical/chemical properties, and determines the maximum internal concrete temperature above which the concrete properties will be affected. A survey of current U.S. highway agencies showed that most of those who responded to the survey believed that mass concrete pours should be controlled by a maximum differential temperature, which most agencies currently specify, and a maximum curing temperature, which most agencies do not currently specify. The reason for supporting the specification of a maximum curing temperature was to avoid durability problems, later age strength reduction, delayed ettringite formation, and cracking due to expansion of concrete. Experiments revealed that when pure portland cement concrete samples were introduced to a controlled ascending temperature rise approximating conditions of mass concrete cured in the field, there was a moderate reduction in 28-day compressive strength and a significant increase in permeability compared to samples cured at room temperature. Results of compressive strength tests and rapid chloride permeability tests showed that the addition of blended cement improves strength and durability of concrete. Microstructural analysis of mortar samples sieved from the concrete mixes using the scanning electron microscope showed that addition of pozzolanic materials reduces the possibility of formation of delayed ettringite. It also identified the formation of delayed ettringite in samples 28 days and older where curing temperature was 160 deg F and 180 deg F. Based on these findings, it is recommended that use of fly ash or slag as a cement replacement should be required in mass concrete since these pozzolanic materials reduce the detrimental effect of high curing temperature on strength and durability of pure cement concrete. When pozzolanic materials are used as a cement replacement, based on ideal laboratory conditions and accurate batching proportions, an 8 to 15 percent reduction in compressive strength due to elevated curing temperature was found with no adverse effect on durability. More study is needed to examine the microstructural analysis of samples cured at temperatures more than 160 deg F, specifically for detection of delayed ettringite formation.

• Record URL:
  https://fdotwww.blob.core.windows.net/sitefinity/docs/default-source/research/reports/fdot-bc354-29-rpta.pdf
• 
• Corporate Authors:

  University of Florida, Gainesville

  School of Building Construction, P.O. Box 115703
  Gainesville, FL  United States  32611

  Florida Department of Transportation

  Haydon Burns Building, 605 Suwanee Street
  Tallahassee, FL  United States  32301

  Department of Transportation

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Chini, A R
  • Muszynski, L C
  • Acquaye, L
  • Tarkhan, S
• Publication Date: 2003-2-26

Language

• English

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: 165 p.

Subject/Index Terms

• TRT Terms: Admixtures; Aging (Materials); Chemical properties; Compressive strength; Concrete curing; Concrete placing; Cracking; Durability tests; Ettringite; Expansion; Experiments; Fly ash; Highway departments; Laboratory tests; Mass concrete; Microstructure; Permeability; Physical properties; Portland cement concrete; Slag; Specifications; Strength of materials; Surveys; Temperature
• Uncontrolled Terms: Delayed ettringite formation; Pozzolanic materials
• Subject Areas: Highways; Materials; I32: Concrete;

Filing Info

• Accession Number: 00941145
• Record Type: Publication
• Report/Paper Numbers: Final Report
• Contract Numbers: BC 354-29
• Files: TRIS, USDOT, STATEDOT
• Created Date: Apr 4 2003 12:00AM