RES2020-06: Use of recycled concrete aggregate in new concrete mixes

Natural virgin aggregates (NVAs) have become gradually exhausted across the state of Tennessee. There is a growing need for the Tennessee Department of Transportation (TDOT) to replace NVAs with more sustainable recycled concrete aggregates (RCAs). It is the intention of the project to quantitatively assess various RCAs available in Tennessee and to explore their suitability for TDOT new paving concrete mixes. This report documents the main findings of the project. A total of eight RCAs were collected representing different concrete origins of pavement, returned concrete, and mixed sources including buildings. Their basic properties were evaluated, including size and gradation, specific gravity, absorption, LA abrasion loss, chloride content, and pH value. These properties were observed to vary widely with RCA sources. This report also covers how RCAs affected the performance of concrete. It becomes evident that RCAs from good quality concrete origins such as pavements can be used in new paving concrete when adequately designed and proportioned. They demonstrated similar performance as NVAs. However, RCAs from unknow or mixed sources should be used with cautions as they may have inconsistent quality. Poor quality RCAs reflected by high absorption, high LA abrasion loss, and low specific gravity due to unsound adhered paste are not recommended for paving concrete because they will substantially reduce the strength and durability of concrete. RCAs with nondurable aggregate origins are also unsuitable for paving concrete applications.

• Record URL:
  https://www.tn.gov/content/dam/tn/tdot/long-range-planning/research/final-reports/2020-final-reports-and-summaries/RES2020-06_Final_Report_Approved.pdf

Language

• English

Project

• Status: Completed
• Funding: $219281
• Contract Numbers:

  RES2020-06

  40100-07219

• Sponsor Organizations:

  Tennessee Department of Transportation

  James K. Polk Building
  Fifth and Deaderick Street
  Nashville, TN  United States  37243-0349
• Managing Organizations:

  Tennessee Department of Transportation

  James K. Polk Building
  Fifth and Deaderick Street
  Nashville, TN  United States  37243-0349
• Project Managers:

  Porter, Jeffry

• Performing Organizations:

  Middle Tennessee State University, Murfreesboro

  1301 East Main Street
  Murfreesboro, TN  United States  37132-0001
• Principal Investigators:

  Yang, Zhifu

  Brown, Heather

• Start Date: 20190701
• Expected Completion Date: 20220131
• Actual Completion Date: 0
• USDOT Program: Transportation, Planning, Research, and Development

Subject/Index Terms

• TRT Terms: Concrete aggregates; Landfills; Paving materials; Quality control; Recycled materials; Sustainable development
• Geographic Terms: Tennessee
• Subject Areas: Highways; Materials; Pavements;

Filing Info

• Accession Number: 01744169
• Record Type: Research project
• Source Agency: Tennessee Department of Transportation
• Contract Numbers: RES2020-06, 40100-07219
• Files: RIP, STATEDOT
• Created Date: Jun 26 2020 11:16AM