Magnitude Assessment of Free and Hydrated Limes Present in RPCC Aggregates

The tendency of tufa to block pavement drains in northeastern Ohio can be associated with the total calcium content of the aggregate material. In the present project, Recycled Portland Cement Concrete (RPCC) aggregates are examined when leached with acidic water formed by carbon dioxide dissolved in water. The RPCC aggregates were supplied by the Ohio Department of Transportation (ODOT) from various sections of the interstate highways in the state of Ohio. The locations of sample and a summary of the components in terms of coarse aggregate, fine aggregate, and cement are quoted in the study of D-cracking report. All the RPCC aggregates were around 30 years old. X-ray power diffraction (XRD) data and thermal analysis (thermogravimetry, TG and differential thermal analysis, DTA) data established the portlandite, dolomite, and calcium carbonate content of the RPCC aggregates. The presence of quartz is established from the DTA plots and its relative abundance established from the XRD data. The ethylene glycol test indicated that the free calcium oxide content has been reduced in most samples to around 0.5% due to carbonation over 30 years. All the samples were subjected to leaching tests in the presence of acidic water (CO2 in water) and the concentration of Ca2+ and Mg2+ ions established using Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES). A ratio of Mg/Ca ions >0.60 indicates that the aggregates have higher concentration of Ca2+ ions and may result in the precipitation of calcium carbonate or tufa. In laboratory studies, the ambient temperature of pouring of concrete (below 500 deg F) has shown a higher incidence of tufa precipitation. It may be due to incomplete hydration. The study recommends establishing Mg/Ca ratio before using RPCC aggregates as base/subbase course. Also it is recommended to limit the use of RPCC aggregates to coarse size only.

• Record URL:
  http://digitalarchive.oclc.org/request?id%3Doclcnum%3A50245025
• Record URL:
  https://ntlrepository.blob.core.windows.net/lib/19000/19600/19600/PB2002108304.pdf
• 
• Corporate Authors:

  University of Toledo

  Department of Civil Engineering, 2801 West Bancroft Street
  Toledo, OH  United States  43606-3390

  Ohio Department of Transportation

  1980 West Broad Street
  Columbus, OH  United States  43223

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Gupta, Jiwan D
  • Dollimore, David
• Publication Date: 2002-2

Language

• English

Media Info

• Media Type: Web
• Edition: Final Report
• Features: Appendices; Figures; Photos; References; Tables;
• Pagination: 211p

Subject/Index Terms

• TRT Terms: Aggregates; Base course (Pavements); Calcium; Calcium carbonate; Calcium oxide; Cement; Coarse aggregates; D cracking; Dolomite; Drains; Ethylene glycol; Fine aggregates; Hydration; Laboratory studies; Leaching; Portland cement concrete; Quartz; Subbase (Pavements); Thermal analysis
• Identifier Terms: Inductively Coupled Plasma-Atomic Emission Spectroscopy
• Uncontrolled Terms: Portlandite; Recycled concrete aggregate; Tufa; X-ray diffraction
• Geographic Terms: Ohio
• Subject Areas: Geotechnology; Highways; I36: Aggregates;

Filing Info

• Accession Number: 01024456
• Record Type: Publication
• Report/Paper Numbers: FHWA/OH-2002/014
• Contract Numbers: State Job No. 14676(0)
• Files: NTL, TRIS, ATRI, USDOT, STATEDOT
• Created Date: May 22 2006 11:34AM