The Art of Placing Quality Pavements
Improving Paving Quality
What's New in Concrete Reinforcement Technology?
Safety Matters
Group Seeks Papers on Pavement Preservation
Products & Services Spotlight

Slipform paving revolutionized concrete paving by using machines that could extrude wet concrete and help both in the formation and control of a long ribbon of pavement, according to information supplied on ACPA's website.

The first half-mile of slipform paving was constructed in O’Brien County, Iowa, in 1949 (1). Since then, slipform paving has become one of the most basic yet critical steps in using concrete for highway, local road, and airport infrastructure.

Quality concrete paving today is not only about what happens directly with the slipform paver, it's also about what comes before and after the paver.

In this issue of CONCRETE PAVEMENT PROGRESS, we examine some of the associated processes, including quality assurance/quality control, safety, and pavement reinforcement technologies. These and many other factors contribute to durable, sustainable concrete pavements, which provide road-users, taxpayers, and agencies the best value possible.

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(1) Source: "Slipform Paving as Developed and Pioneered in Iowa," Iowa State Highway Commission, 1961, cited in TRIS Online database, Transportation Research Board of the National Academies.

Placing quality concrete pavements requires attention to detail at every step of the process. By understanding proper quality assurance/quality control (QA/QC) operations, contractors and owners can be assured of successful results.(1)

QA consists of all the activities conducted by the owner agency to confirm the delivered pavement meets specifications, according to the National Concrete Pavement Technology Center (CP Tech Center). QC involves all the activities contractors perform to ensure the product will meet or exceed specifications. These actions include batching, placing and finishing, according to the CP Tech Center.

QA and QC testing require different methods because not all performance specifications are directly measurable, and not all lab tests can be completed in the field, according to the CP Tech Center, which advises paying close attention to the following steps to make process control adjustments and achieve greater uniformity:

• Focus on repeatability and reproducibility when testing. QA and QC personnel should be adequately trained and certified. Testing facilities also should be certified by qualified organizations.

• Use proper documentation of testing data for accurate interpretation. Steps include: using clear and consistent labeling of samples; accurate recording of sample locations and times; legible handwriting; and an organized file system.

• Continuously monitor and calibrate the batch plant. This will help to maintain control of water-to-cementitious materials ratio, aggregate moisture and materials batching tolerances.

• During construction, continuously monitor and make adjustments as necessary. Specific elements to pay attention to include: concrete temperature, air-void system results, vibration amount, and joint placement time and locations.

For questions regarding QA/QC, contact Mike Ayers at 217-621-3438.

The National Concrete Pavement Technology Center (CP Tech Center) is located at 2711 South Loop Drive, Suite 4700, Ames, IA 50010. Phone: 515-294-5798

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(1) Quality Assurance and Quality Control: Technical Summary. National Concrete Pavement Technology Center. Excerpted from the Integrated Materials and Construction Practices for Concrete Pavement: A State-of-the-Practice Manual. August 2007.

What’s New in Concrete Reinforcement Technology?

Concrete reinforcement technology is evolving to meet the changing needs of agencies and contractors. ACPA CONCRETE PAVEMENT PROGRESS asked representatives of three manufacturers to comment on the current and future direction for this technology. *

Our roundtable was comprised of:
- Nigel Parkes, PNA Construction Technologies, Inc.
- Roger Stutzman, MMFX Technologies Corp.
- Shane Whitacre, P.E., American Highway Technology (AHT)

CPP: Describe briefly the basic technology your company offers in the area of pavement reinforcement products.

Parkes: PNA Construction Technologies, Inc. produces plate dowel systems for load transfer at free-movement joints.

Stutzman: MMFX Technologies Corp. produces a low-carbon, chromium alloy microcomposite steel. This is an economical, high-quality, fine-grained steel with a reduced amount of impurities, compared to standard carbon steels.

Whitacre: AHT offers load transfer devices, which can include automated machines for the construction of welded baskets and dowels.

CPP: What are some of the most pressing needs of your contractor customers, and how does your technology help them overcome them?

Parkes: Our customers, now more than ever, are looking for cost-effective solutions that help them maintain profit margins without sacrificing the quality of their concrete flatwork.

We’re seeing many contractors who are actively proposing design alternatives that include tapered plate dowel technology to create material savings and improve the long-term performance of concrete flatwork. Tapered plate dowels reduce the bearing stress on concrete and eliminate dowel erosion. Tapered-shaped load plates reduce restraint by allowing the concrete to shrink freely in all directions on a horizontal plane and provide more steel where it’s needed most—at the joints while reducing the total amount of steel required.

Stutzman: Our customers sometimes need information on how our steel is used in concrete paving applications as specified by various end users or their consultants.

Whitacre: Lead times are a pressing need for our contractor customers. With the quickly-rising cost of steel products, contractors want to be able to order products and have them produced and shipped as quickly as possible to avoid cost escalators. Contractors also would like to see more standardization of wire and dowel sizes used across the country.

CPP: What are some of the current expectations from agencies, in terms of product quality, product durability, and specifications/standards?

Parkes: Agencies are trying to conduct repairs to extend the life of existing roads and install more durable infrastructure, while also shortening construction and being cost-effective.

Thus, agencies must be able to rely on suppliers to consistently deliver quality products proven to perform for the life of the pavement. And, more importantly, they need to work with suppliers that deliver product on time, every time, so there are no extended construction delays.

Stutzman: We’ve found that by distributing a comprehensive report on our product, state agencies understand microcomposite steel dowel bars’ enhanced corrosion resistance and pavement life expectancy. However, we still must work with them to obtain their approval on the products. To make this easier, we’ve provided draft standard construction specifications and special provisions.

Whitacre: The majority of agencies involved with load transfer like to see consistency in quality and construction, materials found on the qualified products lists, and materials from approved steel mills, as well as certified coatings. We're challenged with encouraging agencies to study the use of alternate materials for load transfer, instead of relying solely on steel.

CPP: How do you work with contractors and agencies to overcome these challenges?

Parkes: We work with ACPA and contractors to help educate people on the engineered performance and construction benefits tapered plate dowels offer.  We are working with agencies on testing additional elements of pavement performance, such as the expected lifespan of thinner sections of pavements using different types of load transfer devices.

Stutzman: MMFX is working with the American Association of State Highway Transportation Officials to establish a new national standard specification for uncoated, corrosion-resistant steel for concrete reinforcement and dowels. We also work with state DOT's on product test programs, product approvals, and standard construction specifications.

Whitacre: AHT stays in contact with the state DOT's, Federal Highway Administration, and Federal Aviation Administration to keep them updated on emerging technology, industry practices, and ongoing testing of materials. AHT also works through the ACPA committees and other organizations to have a voice as the industry moves forward.

Protecting the safety of agency and contractor employees plays a major role in a successful concrete pavement job, but it doesn't stop on the grade.

At the project site, awareness is key to maintaining the safety of all employees, according to
Fred Hite, General Manager, Power Pavers, Inc.

Hite also says taking the proper precautions during the paving process can ensure employees return home in the same condition they arrived.

He adds:

• First and foremost, maintain awareness of the situation at all times. With a fully automated machine such as a slipform paver, it is easy for an operator to lose attention or get distracted during long periods of operation.

• Other employees on the grade should stay clear of anything that moves on the machine, as functions and attachments may actuate automatically while the machine is in operation.

• Stay clear of the concrete trucks, as they may move forward or backward without notice—the drivers are often focused on discharging concrete, not the workers walking around the truck, Hite said.

• During paving, make sure all guards and safety shields are in place, and that all emergency stop switches are functional.

• After paving, turn off augers before pressure washing or cleaning because hoses and loose clothing may become entangled, leading to severe injury or death.

And finally, Hite says, never leave the machine unattended while the engine is running.

ACPA's new literature series of technical briefs offers quick and ready information for contractors, consultants, agencies, and others.

Each publication in the new Technical Series (TS) is a two-page summary of specific concepts derived from more comprehensive ACPA technical publications.

The first documents cover a number of topics from EB204P: Subbases and Subgrades for Concrete Pavements, as well as thin concrete overlays from EB240P: Concrete Pavement Overlays, which is set for release in 2010. Click here to download free copies of the documents.

supplement the technical instruction provided.

The 118-page manual also contains a series of checklists aimed at guiding and assisting paving crews with proper procedures on the grade. Click here to download the checklists for free online.

EB237P—Concrete Pavement Field Reference: Pre-Paving is the second in a three-part series of manuals aimed at assisting agencies, contractors, engineers, and consultants. The first manual, EB239P—Concrete Pavement Field Reference: Preservation and Repair, is available for purchase by clicking here. The final reference will focus on construction and is expected to be released by early next year.

Click here to order a copy online. Alternatively, call ACPA/PCA Customer Service 1-800-868-6733.

An Alternative to Traditional Round Dowel Bars covers plate dowel innovations driven by trends in industrial concrete paving.

The four-page technical brief is aimed at agencies, contractors, engineers, and anyone requiring updated information on dowel innovations for concrete pavement.

The publication includes:
• The evolution of dowel geometry in industrial paving.
• Explanations of failure modes and how plate dowel geometry addresses them.
• Typical dowel arrangements.
• Detailed illustrations and images.

Click here to download a free copy of this and other ACPA R&T Updates.