Summary of Michigan Recycled Concrete Aggregate Review
August 19-23, 2003
The Michigan Department of Transportation's (MDOT) strategy for the recycling and reuse of concrete aggregate is to use it if it enhances or equals the performance of virgin material in the final product. Statewide use of recycled concrete aggregate (RCA) is permitted in the Standard Specifications of Construction, 2003, Aggregate section 902.03 part B, 902.04, and 902.06. It allows the use of RCA as coarse aggregate for Portland cement concrete for curb and gutter, valley gutter, sidewalk, concrete barriers, driveways, temporary pavement, interchange ramps, and shoulders. RCA is also allowed as coarse aggregate in hot mix asphalt and as dense-graded aggregate for base course, surface course, shoulders, approaches and patching. RCA was widely in the pavement structure during the 1980's. However, in 1991, a moratorium was implemented on the use of RCA in the PCC pavement slabs.
Since 1983 MDOT has incorporated RCA in projects such as M-10, I-75, I-94, I-95, and I-96. Michigan has constructed 26 projects with 650 lane miles of PCC pavements using recycled concrete aggregate. US-41 in the Upper Peninsula is currently being reconstructed using RCA as the base material with a mobile crushing operation. In addition, the Detroit Metro region is currently using RCA as a base material on 2 projects.
MDOT and aggregate producers identified the following benefits for RCA:
- RCA used in the base and sub-base material can have performance comparable to virgin aggregate where recycled material is allowed.
- Damage to the highway infrastructure can be reduced due to proximity of aggregate crushing plants.
- D-Cracking performance problems in RCA pavements can be reduced when the old pavement is crushed to a smaller aggregate size.
- Substitution of virgin aggregate by RCA can provide a reduction in the final cost of the project.
- Using RCA in the Detroit metropolitan region is more advantageous than in rural areas of the state, since sources of old concrete are readily available and virgin aggregate sources are not as plentiful.
- The proximity to metro areas of the RCA production plants makes this aggregate economically attractive for commercial uses in base and parking lots.
- A recent value-engineering proposal for RCA in the pavement structure on US-41 resulted in savings of $114,000 on a 3 million dollar project. This savings was shared in equal parts by the contractor and the state.
- Reduction of landfill disposal material.
- Currently, the demand for disposal space for concrete debris is high in the Detroit Metro area. The recycling plants are reaching their stock capacity, and the disposal costs are increasing. This demand is considerably diminished when RCA has an engineered use in projects around this area.
- Reduction of fuel consumption by decreasing or even eliminating haul distances.
- Preservation of natural aggregate resource.
MDOT and local aggregate suppliers have been using RCA for over 19 years and have overcome some barriers. A summary of MDOT and aggregate industry's experiences are provided below.
- Recommendations given by MDOT and Detroit Metro region for using RCA in state highways for durability, bonding, and strength are:
- Quality assurance and quality control of materials is needed to assure meeting specifications.
- Normally commercial sources of concrete are not allowed for recycling in the crushing plants. Most recycled material comes from the MDOT's reconstruction projects. This assures a consistent source of original aggregate.
- Certification of recycling aggregate producers and the approval of stockpiles, when the primary source is the concrete from highways.
- Changes in the design on the permeable base allow RCA to be used when the density of material is increased and the design of the drainage system is modified.
- Recommendations given by a MDOT Research Record of Oct 1995, indicate ways for reducing cracking when using RCA in highways that will enhance its performance by minimizing reliance on aggregate interlock:
- Increasing of foundation stiffness
- Reduction of slab tension
- Additional steel reinforcement
- Use of a deformed wire mesh
- Use of hinge joints
- Establishment of Environmental Policy:
- Using Recycled material when it cost up to 10% more than natural material
In 1988 MDOT announced a construction moratorium on using RCA in PCC pavement because of the premature transverse cracking, faulting, and spalling problems presented in the earlier recycled projects on I-94 and I-75. Until 1990 the constructors could use a blend of RCA and natural aggregate in PCC pavements, but in 1991 MDOT reinstated the moratorium on RCA in any mainline pavement because results from Michigan State University showed that the aggregate blend did not improve the behavior of pavements. "Uses of Recycled Concrete in Michigan", a report made by The University of Michigan, suggested that the use of RCA was not the only factor that affected the pavements performance. Other factors of influence named in this report were the design of the base, the uniformity of the foundation layers, the stiffness of the sub-grade material, the thickness of the pavement slab, and the weather (temperature) when the concrete was placed.
One project that has performed well is the M-10 project in the Detroit area, possible due to the low volume of heavy truck traffic.
MDOT and aggregate suppliers still are looking to gain additional experience or information in the following areas:
- Improving the design specifications for RCA's use in concrete.
- Effect on drainage system.
- Actual resilient modulus value for use in design equations.
- Documented experience in long terms performance in base.
- Uniformity of criterion for RCA throughout the state.
- Demonstration projects.
People in Attendance at Discussion Groups
Performance, Design, Materials, & Research. August 19, 2003.
|Kurt S. Bancroft
||Engineering Technician 12. MDOT.
||Engineering Technician. Construction & Technology. Materials. MDOT.
|Douglas E. Branch
||Materials Investigator. Materials Research & Testing Group. Construction
& Technology MDOT.
||Pavement Design Engineer. Pavement Management Unit. MDOT.
||Transportation Engineer. Pavement Rehabilitation Studies. Construction
||Supervising Engineer Pavement Structures Group. Pavement Preservation.
Construction & Technology. MDOT.
|John F. Staton
||Supervising Engineer, Materials Research Group. Construction & Technology.
Project Administration. August 20, 2003
|Michael L. Cornacchia
||Material Supervisor. MDOT. Metro Region
|Cedric W. Dargin
||Resident Engineer. Transportation Service Center. MDOT. Metro Region.
||Delivery Engineer. MDOT. Metro Region.
|Mark J. Grazioli
||Soils& Materials Managing Engineer. MDOT. Metro Region.
The following is a list of the materials that have been provided to the review team:
History of Use: Recycled Concrete Coarse Aggregate. Michigan Department of Transportation. (FHWA National Review 8/03).
Pavement Design and Selection Manual. Pavement Management Unit. Construction & Technology Division. Michigan Department of Transportation. October, 2002.
A Guide for Compliance with the Air Regulatory Requirements for Particulate Matter Generation. Managing Fugitive Dust. Michigan Department of Environmental Quality. Environmental Science and Service Division. Clear Air Assistance Program. March, 2003.
General Permit to Install for Nonmetallic Mineral Crushing Facilities. Michigan Department of Environmental Quality. Air Quality Division. Revised April 1, 2003. http://www.deq.state.mi.us/aps/downloads/permits/Crush%20Jan%2003.pdf
Permit to Install Exemptions; Miscellaneous. R336.1285. July 1,2003.
Solid Waste Management Act Administration Rules Promulgated Pursuant to Part 115 of the Natural Resource and Environmental Protection Act, 1994 PA 451. As Amended. Michigan Department of Environmental Quality, Waste Management Department Division. Effective April 12, 1999.
MERA Operational Memorandum #8, Revision 3-Type B Criteria. Rules 299.5709, 299.5711(2), 299.5711(5), and 299.5713. Alan J. Howard, Environmental Response Division, Inter-Office Communication, February 4, 1984Calcium Carbonate Precipitate From Crushed Concrete. R. W. Muethel. Research Laboratory Section. Materials & Technology Division. Michigan Department of Transportation. March, 1989.
Air Pollution Control Rules. http://www.michigan.gov/deq/0,1607,%207-135-3310_4108-10415--,00.html
Natural Resources and Environmental Protection Act. Fugitive dust sources or emissions. Act 451 of 1994.Part 55. http://www.michiganlegislature.org/mileg.asp?page=getObject&objName=mcl-324-5524&queryid=4415526&highlight=
The Management and Budget Act.18.1261a Recycled supplies, materials, and equipment; effect of noncompliance; exemption; cost considerations; report; "recycled materials" defined. Act 431 of 1989.
Michigan Department of Transportation. Special Provision For Aggregate Sub-base. Metro: RWO. C&TAPPR:DLS:J L:09-25-01.
Angelo's Crushed Concrete, Inc. "Concrete Solution". CD-video presentation.
The following is a list of sites visited:
- The Iafrate Crushing Plant was visited. It is located at 6873 Inkster Road, Taylor, MI, outside Detroit. It was observed recycled concrete stockpiles and their crushing process. The maximum size of the RCA produced was 3".