Utilization of Regular or Carbonized RCA for KDOT Paving

Concrete pavements in Kansas experience on average thirty-three freeze- thaw cycles during a year in-service. Both the aggregate and the cementitious paste are susceptible to freeze-thaw deterioration. KDOT has implemented minimum air content requirements for concrete mixtures and prequalification of aggregate using KTMR 22 (a 9-month testing procedure) to minimize premature freeze-thaw deterioration of pavements. The implementation of strict prequalification requirements has enhanced durability but restricted availability and increased costs of coarse aggregate (predominantly limestone in Kansas) for paving. Recycled concrete aggregate (RCA), produced by crushing out-of-service concrete structures and pavements, can be a viable alternative to virgin aggregates for producing concrete for paving applications. Studies conducted by various state DOTs (Indiana, Tennessee, Iowa) show that replacement of virgin aggregate with RCA resulted in some (0 – 25%) reduction in freeze-thaw durability of the resulting concrete. The reported variability in the freeze- thaw performance can be attributed to (a) the source of RCA and/or (b) non-uniformity in mixture designs studied across different state DOTs. In particular, for concrete mixtures containing fly ash, the freeze-thaw performance of concrete containing RCA was similar to that of concrete prepared using virgin aggregates. Furthermore, all studies concluded that concrete containing RCA showed lower mechanical properties than concrete prepared using naturally mined aggregates. The high porosity of RCA was deemed responsible for the observed reduction in mechanical properties, especially flexural strength. During the carbonation of RCA CO2 reacts with Ca(OH)2 to form calcium carbonate, which is harder and has larger solid phase volume than Ca(OH)2. Therefore, carbonated RCA (cRCA) has lower porosity than RCA and consequently the concrete prepared using cRCA shows better mechanical properties compared to concrete prepared using RCA. Furthermore, concrete containing cRCA has also showed lower gas and water permeability, chloride permeability, and carbonation depth compared to concrete prepared using RCA. However, no investigation has been conducted to evaluate the freeze-thaw resistance of concrete prepared using cRCA. Therefore, the research outlined in this proposal seeks to determine the performance characteristics of RCA and cRCA for KDOT paving.

Language

• English

Project

• Status: Active
• Funding: $40189
• Contract Numbers:

  K-TRAN: KSU-24-5

  RE-0878-01

  C2227

• Sponsor Organizations:

  Kansas Department of Transportation

  Eisenhower State Office Building
  700 SW Harrison Street
  Topeka, KS  United States  66603-3754
• Performing Organizations:

  Kansas State University Transportation Center

  Kansas State University
  Department of Civil Engineering
  Manhattan, KS  United States  66506
• Principal Investigators:

  Panchmatia, Parth

• Start Date: 20230715
• Expected Completion Date: 20250115
• Actual Completion Date: 0

Subject/Index Terms

• TRT Terms: Concrete aggregates; Concrete pavements; Freeze thaw durability; Pavement performance; Recycled materials; State departments of transportation
• Geographic Terms: Kansas
• Subject Areas: Highways; Materials; Pavements;

Filing Info

• Accession Number: 01894620
• Record Type: Research project
• Source Agency: Kansas Department of Transportation
• Contract Numbers: K-TRAN: KSU-24-5, RE-0878-01, C2227
• Files: RIP, STATEDOT
• Created Date: Sep 26 2023 3:50PM