Concrete roads are durable and long-lasting, requiring only targeted rehabilitation and diamond grinding every 25 years or so. With repairs on concrete roads being performed infrequently, however, cities may face a learning curve when it comes to understanding the available repair tools.
In 2015, Baytown, Texas faced ride quality issues on its N. Main Street and the Public Works and Engineering Department searched for a cost-effective repair strategy that would perform well considering the unique properties of the street’s pavement:
• Concrete road that was installed in the 1980s—
• Major right-of-way in the Houston-area City of Baytown
• Two lanes in each direction as well as a turn lane
• Truck route that serves nearby industrial areas
• Aggregate used in the original construction was river rock, an exceptionally hard material
• Measurements from hardness tests on the N. Main Street aggregates were an 8 on the Mohs scale of mineral hardness (diamonds measure a 10)
• Some of the ride quality issues that had developed on the roadway were due to the wearing away of the cement paste layer and consequent exposure of the rock.
The department worked with educational institutions and industry experts to identify challenges. They came up with a solution that resulted in a project that was dramatically lower in cost—by 80%—than initial estimates. Pavement condition index (PCI) measurements: 0 = worst conditions and 100=best. The sections of pavement averaged 43, with 4 sections in low 20s to mid-30s.
Reconstruction was considered, but the city didn’t have adequate funding for a project of that scope. Someone during researching mentioned to the Public Works and Engineering Department that concrete pavement preservation (CPP) was an option.
What is Concrete Pavement Preservation?
CPP is a series of engineered techniques developed over the past 50 years to manage the rate of pavement deterioration in concrete streets, highways and airports. CPP is:
• A non-overlay option used to repair areas of distress in concrete pavement without changing its grade
• Unlike overlays, CPP fixes underlying sources of pavement distress
• Consists of targeted treatments such as full- or partial-depth panel replacement, dowel bar retrofit, cross-stitching, crack repairs, and more
• By addressing problems at their source, CPP prevents ongoing deterioration
• Reduces the need for more costly repairs in the future
• After CPP, pavement condition is close to or better than that of the original!
Meeting With Experts
Because the City of Baytown had no experience with a CPP program, one of the first steps was to meet with experts to learn more. The Public Works and Engineering Department consulted with:
• The states Minnesota and Kansas who had experience with CPP
• Took online training classes through the University of Iowa‘s National Concrete Pavement Technology Center (CP Tech Center) who offer courses via webinar, video and other channels
• International Grooving & Grinding Association (IGGA)—a trade association that serves as a technical resource for pavement preservation and restoration “YOUR PAVEMENT PRESERVATION RESOURCE SINCE 1972”
CP Tech CPP Courses: https://cptechcenter.org/webinars-and-videos/
The relationships the department formed were maintained throughout the N. Main Street project and guided the CPP process from its earliest phases through to project completion. During project planning, IGGA experts and Baytown officials conducted an in-person inspection of the roadway, confirming that the pavement showed adequate structural integrity and was a good candidate for CPP. They then worked together to develop specifications, gleaning insights from the states with detailed specifications already in place, and collaborated during the contractor search and bidding processes. When Interstate Improvement (a highway contractor based in Faribault, Minnesota who performs work nationwide) was selected to perform the CPP, that company also became involved at an early stage, with project manager Nathan Sirek visiting the city and consulting with department officials prior to the start of work. Together with Interstate Improvement and IGGA, the city identified the proper repair procedures for individual distressed areas.
The Work Done
- Construction began in 2020 and was completed in Spring 2021. The City of Baytown replaced approximately 20% of the road surface on the N. Main Street section, with work including:
- Full-depth panel replacement
- Approximately 47,000 sq. yds. of diamond grinding, at 1/8 to 1/4 in.
- Dowel-bar retrofit (using 300 dowel bars) for transverse cracks
- Cross-stitching (using 2,500 deformed rebars) for longitudinal cracks and joints
- Replacement and resetting of manholes
Crack Repair & Sealing
The project was a success by all measures! Cost savings were enormous, with CPP treatments being completed for $2.2 million—less than 20% of the cost of reconstruction—saving the city approximately $10 million.
PCI measurements improved to an average of 75-80.
The department officials AND residents were pleased with the rideability of the finished road surface!
The City of Baytown expects to continue its successes with CPP in the upcoming 2022 construction season!
Work will be performed on several residential streets and the city will optimize its return-on-investment by ensuring that involved personnel receives the proper training and by selecting future projects using lessons learned on the N. Main Street project. For example:
• Hard aggregates used on many of the city’s concrete streets mean that project sizes will be limited due to grinding having to be done much more slowly on hard surfaces
• Projects will be timed to occur when PCI scores are in the 50s-70s, thereby controlling the scope of repairs needed and keeping the project in line with pavement preservation (as opposed to full reconstruction)
• Streets targeted for CPP will ideally require 10% or less in panel replacements and any panel settlement will be corrected with panel lifting prior to the start of grinding
• Determining the number of panels needing replacement, crews will perform surveys by walking the project, since exposed aggregates can make cracks difficult to see
• N. Main Street project conducted some half-lane repairs to save time and money, so future wider repairs will be performed because they impart greater consistency to the finished surface
• Project scheduling is critical to success—for example:
– Dowel bar retrofit should begin at least a week before grinding is scheduled
– Equally important to have grinding work completed in a timely manner, to maintain good ride quality for the driving public
CPP provides a cost-effective repair option for concrete streets while returning the pavement surface to a like-new condition and improving ride quality for the driving public. It keeps existing roads in good structural condition and ensures continued durability for decades to come. For cities looking to stretch their budgets, achieve sustainability benchmarks, and have high-quality roads, CPP is a wise approach.
For the pavement condition index (PCI) measurements; dowel specs; dollar figures; and the complete Concrete Contractor article titles “Case Study: How Concrete Pavement Preservation Saved $10M in Road Repair”, please go to: www.forconstructionpros.com/concrete/article/21977626/case-study-how-concrete-pavement-preservation-saved-baytown-texas-80-of-road-repair-costs
IGGA: www.igga.net
CP Tech Center: https://cptechcenter.org
CP Tech CPP Courses: https://cptechcenter.org/webinars-and-videos/
Interstate Improvement: www.interstateimprovement.com
Photos: (1). Diamond grinding operation. (2).Full-depth repairs of the concrete road. (3). Manhole reset followed by diamond grinding. Photos: Courtesy Kevin Harvill, City of Baytown, TX
For the ISCP CPP VIDEO pertaining to this article and adjacent to this article on the ISCP homepage, please go to: www.concretepavements.org/2022/01/22/video-cpp-helps-concrete-pavements-achieve-maximum-longevity/