Modern Roads

Fig. 1 CRCP Road Construction in Texas.[1]

What is CRCP?

A CRCP Resurgence – Technical Overview and Best Practices

by Michael N. Plei, PE


Continuously Reinforced Concrete Pavement (CRCP) is enjoying a comeback of sorts in many parts of the world including the United States. Why the renewed interest? When best-practice design and construction are employed, CRCP roads can offer a long-term, low-maintenance service-life, even under heavy traffic loads and challenging environmental conditions. The idea of “build it and leave it” is an appealing proposition to many transportation organizations facing budget cut-backs.

This article provides an overview of CRCP and some recommended best practices. Much of this information is adapted from a more detailed TechBrief that I wrote for the Federal Highway Administration along with my co-author Shiraz Tayabji, Ph.D., P.E.[2]

CRCP Design

CRCP is a rigid pavement built with concrete and steel reinforcing bars. CRCP contains longitudinal steel reinforcing bars made continuous throughout the pavement length. These longitudinal bars eliminate the need for transverse control joints – except at the ends. This feature allows CRCP to run joint free for many miles.

A key design feature of CRCP is its ability to manage cracks that develop in the pavement without the use of transversal joints. Most transverse cracks form at an early stage even before the pavement is open to traffic. This cracking may continue for several years after concrete placement. Failure to manage cracks can lead to significant pavement damage (e.g., punchouts, steel rupture, and crack spalling).

CRCP does not try to prevent the concrete from cracking. Nor does it enable the cracks to happen in a designated area (i.e. transversal joints as in JPCP). CRCP allows cracking to happen in a controlled pattern and holds cracks tightly together to limit their growth and opening. By limiting the growth and widening of the cracks, CRCP reduces the chance of significant pavement damage and distressed over its lifetime.

Designing CRCP involves determining the proper combination of slab thickness, concrete mixture constituents and properties, and steel reinforcement content and location; providing for sufficient slab edge support; strengthening or treating the existing soils; providing non-erodible bases that also provide friction that leads to desirable transverse cracking patterns. While most of these features are common to all good pavement designs, reinforcement and edge support are particularly critical to a CRCP.

Several highway agencies have implemented the new mechanistic-empirical pavement design procedure and the associated Pavement ME Design software design of CRCP. However, several other highway agencies continue to use AASHTO’s 1993 Pavement Design Guide for design of CRCP.


The continuous longitudinal reinforcement (typically grade 60 bars) used in CRCP keeps cracks in the concrete tight which prevents their growth and widening. Modern CRCP is built with longitudinal reinforcing steel with percentages between 0.65% to 0.80% (lower in milder climates and higher in harsher climates).

Equally important as the percentage of steel content is the bond area between concrete and bars. The Federal Highway Administration recommends at a minimum of 0.030 square inch per cubic inch of concrete.[3]


Vertical bar placement affects performance. Bars placed too high may corrode due to inadequate coverage. Bars placed too low will not keep the cracks tight at the surface. It is common practice to position the reinforcement bars between one-third and one-half the slab thickness measured from the pavement surface.[4]

In modern CRCP, transverse bars are always used to support the longitudinal reinforcement bars. In addition to support, the transverse bars also keep tight any longitudinal cracking that may develop. The transverse bars are placed on bar supports which must be kept stable and should not sink into the base prior to paving.

Edge Support / Shoulders

Proper support of the shoulder/edge adjacent to mainline CRCP reduces wheel-load stresses and deflections. The benefit of this practice is fewer pavement punchouts and longitudinal joint and shoulder maintenance issues. Use of asphalt shoulders was a practice in the past. However, current best practice to improve edge support is to use a tied-concrete shoulder or a widened outside lane.

Common US practice is to construct shoulders out of the same material as the mainline pavement. This practice makes construction easier, improves performance, and reduces maintenance costs.

Another option gaining popularity is to provide a widened outside lane. Research indicates that the slab needs to be a minimum 13’ wide (to minimize longitudinal cracking) and be striped to 12’ to significantly reduce the stresses and deflections caused by heavy truck traffic near the pavement edge.

End Treatments

When meeting structures, two types of end treatments are used for CRCP, namely wide flange beam joints and anchor lugs.

End treatments using a wide flange beam joint serve as expansion joints allowing the ends to move freely as the concrete expands and contracts with changing temperature.

End treatments using anchor lugs consist of several lugs below the slab that are tied into the slab end. These attempt to restrain any movement from taking place at the ends. The use of anchor lugs is not common in current practice due to the difficulty in construction and varied performance.

For short sections of CRCP, conventional doweled expansion joints may be used as part of the approach slabs at a structure.

CRCP Construction

During construction, it is important to focus intently on bar placement, concrete consolidation, and concrete curing. Along with actual concrete strength, these components have the largest impact on transverse crack formation and therefore, long-term performance of CRCP.

Reinforcement Placement

Currently, all bars are placed using the “manual method,” where steel placers install bars by hand prior to paving. The placers ensure bars are placed in the proper vertical position, lap splices are of sufficient length, supports do not impede placing and consolidation of the concrete, and the completed mat does not move during slip-form paving.

The vertical position of the bars is set by the supports and diameters of the transverse and the longitudinal bars with a typical tolerance of plus or minus 0.5”. Horizontal spacing tolerances are less stringent, but it is important that longitudinal bar placement does not impede placement or consolidation of concrete.

Steel bars normally come in standard lengths of 60’ and must be lap-spliced to form a continuous longitudinal mat. The lap-splicing patterns used today are either staggered or skewed. In the past, failures occurred due to improper concrete compaction caused when all laps were located adjacent to each other.

Continuous bar supports, commonly known as transverse bar assemblies (TBAs) can speed up the placement of the steel mat. TBAs are transverse bars with welded steel supports, which serve as chairs, and U-shaped clips. The spacing of the clips along the bar matches that required of the longitudinal bars. The clips hold the longitudinal bars in position vertically and keep them from moving transversely, while allowing a bit of longitudinal movement. This system is more expensive than using individual bar supports, but it decreases installation time significantly.

Concrete Placement

Key to well-performing CRCP is a steady supply of a uniform concrete mixture. A consistent mixture enables a uniform cracking pattern leading to better performance of the CRCP.

A prevalent configuration facilitating a steady, well-mixed supply is shown in Fig. 2. A truck or mixer deposits the concrete into a hopper, which lifts the concrete to a conveyor. The conveyor moves the concrete to the paving machine where the concrete is then spread, vibrated, and slipped.

Fig. 2 Side placement of concrete

Concrete Curing

CRCP can be paved during the day or night. If daytime temperature are very hot, paving at night will allow better temperature control of the concrete and lead to better performing CRCP. Paving at night avoids curing heat and high ambient temperatures occurring at the same time. Specifications limit the concrete temperature to a range of 50 °F to 90 °F.

Other measures to reduce heat include changing the concrete mixture constituents and proportions, wetting the base and steel bars in front of the paver, and whitewashing the asphalt base prior to placement of the reinforcement. (As long as it does not reduce bonding and friction with the CRCP, as this will greatly affect crack spacing and width.)

CRCP Use and Performance

Well-performing CRCP can be identified by a reasonably regular transverse cracking pattern with desirable crack spacing (2’ to 8’) that are kept tight without any signs of pavement distress or failures.

Fig. 3 Above, Cracking in a 25-year-old CRCP pavement, closely spaced and tight, as diagrammed below the photograph.

State Use

Highway agencies in Illinois, Oklahoma, Virginia, North and South Dakota, Texas, and Oregon have used CRCP since the 1960s and 1970s. These agencies have studied CRCP technology in great detail – many times in partnership with the FHWA — learning the best way to build CRCP given the materials, climate and experiences unique to each state. Other highway agencies with significant experience with CRCP include California, Georgia, and Louisiana.

International CRCP Use

Road agencies around the world have been using CRCP almost as long as agencies in the US. CRCP has been built on every continent except Antarctica. Belgium, the Netherlands, South Africa, the United Kingdom, and Australia are the largest users. More recently, Germany and China have also begun experimenting with CRCP.

Perhaps the most important recent development in technology concerning CRCP can be found on the M7 Motorway (Westlink), which was opened in 2005 in the western suburbs of Sydney, NSW, Australia. Technological innovation comes by connecting the CRCP longitudinal reinforcement directly into the bridge deck reinforcement, with additional pavement reinforcement provided in the transition zones, eliminating anchorages and joints to create a "seamless pavement".

Long-Term Pavement Performance Program Data

The best source for a national US overview of CRCP performance is the Long-Term Pavement Performance (LTPP) Program. When General Pavement Study-5 (GPS-5), which studied CRCP over various base layers, began, it included 85 CRCP experimental sections in 29 States and all four LTPP climatic regions.

LTPP GPS-5 data for CRCP test sections were analyzed in 1999 and 2000. These analyses showed the following:[5][6]

  • CRCP test section ages ranging from 5 to 34 years (as of 1999) were observed.
  • Very limited amounts of localized failures were observed (at only 16 sections as of 1995), with only little high-severity cracking observed at these 16 sections.
  • Nine sections were overlaid as of 1995, most due to resurfacing of adjacent sections.
  • Most CRCP sections were performing well with ≥ 15 years (some ≥ 20 years) of service life.
  • Very little distress was reported.
  • Little degradation in ride quality over time was observed, indicating that a CRCP remains smooth for many years.


CRC pavements have a long history of good performance in the United States and other countries when designed and constructed well. Many U.S. highway agencies consider CRC pavements their pavement of choice for implementing long-life pavement strategies that have lower life cycle costs and require fewer lane closures for routine maintenance, repair and rehabilitation.

CRC pavements have also been used on local roads, intersections, and roundabouts and at airports, freight terminals, warehouses, and racetracks.

As discussed in this article and in greater detail in this TechBrief [7], well-performing CRCP and CRC overlays require consideration of the following best practices:

  • Adequate amount of longitudinal reinforcement.
  • Control over depth of steel placement.
  • Well-drained and stable support. For heavy truck traffic projects, use of an asphalt base or a cement-treated base with an asphalt concrete interlayer is recommended.
  • Most CRCP sections were performing well with ≥ 15 years (some ≥ 20 years) of service life.
  • Use of a 13-ft-wide outside lane.
  • Use of slab thickness appropriate for the long-term design traffic.


  1. ^ Continuously Reinforced Concrete Pavement (CRCP) in Texas – Won, Moon, Texas Tech University, Presentation at National Concrete Consortium Meeting March 31 - April 2, 2009 San Antonio, Texas
  2. ^ FHWA-HIF-12-039, Federal Highway Administration (FHWA). 2012, September | FHWA-HIF-12-039. TechBrief, Continuously Reinforced Concrete Pavement Performance and Best Practices. FHWA, Washington, DC., developed by Michael Plei, P.E., Consultant, and Shiraz Tayabji, Ph.D., P.E., Fugro Consultants, Inc.
  3. ^ Continuously Reinforced Concrete Pavement Federal Highway Administration (FHWA). 1990, June 5. Technical Advisory T 5080.14, Continuously Reinforced Concrete Pavement. FHWA, Washington, DC.
  4. ^ Manual of Standard Practice– Concrete Reinforcing Steel Institute (CRSI). 2009. Manual of Standard Practice 2009. 28th Edition. CRSI, Schaumburg, IL.
  5. ^ Preliminary Evaluation of LTPP Continuously Reinforced Concrete (CRC) Pavement Test Sections – Tayabji, S. D., O. Selezneva, and Y. J. Jiang. 1999. Preliminary Evaluation of LTPP Continuously Reinforced Concrete (CRC) Pavement Test Sections (FHWA-RD-99-086). FHWA, Washington, DC.
  6. ^ Texas Department of Transportation – Tayabji, S. D., C. L. Wu, and M. Plei. 2001. Performance of Continuously Reinforced Concrete Pavements in the LTPP Program. In Seventh International Conference on Concrete Pavements: The Use of Concrete in Developing Long-Lasting Pavement Solutions for the 21st Century, pp. 685–700. International Society for Concrete Pavements, College Station, TX. TRID Accession No. 00823449.
  7. ^ FHWA-HIF-12-039, Federal Highway Administration (FHWA). 2012, September | FHWA-HIF-12-039. TechBrief, Continuously Reinforced Concrete Pavement Performance and Best Practices. FHWA, Washington, DC., developed by Michael Plei, P.E., Consultant, and Shiraz Tayabji, Ph.D., P.E., Fugro Consultants, Inc.