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Federal Highway Administration > Publications > Focus > September 1999 > Portland Cement Concrete Pavements Made to Order
September 1999Publication Number: FHWA-RD-99-107

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Portland Cement Concrete Pavements Made to Order

With the recent launch of the long-term pavement performance (LTPP) program's Rigid Pavement Design Software, States have an important new tool to use in designing and building portland cement concrete pavements. The software is in the form of a Microsoft Excel spreadsheet. It allows engineers to tailor the pavement design to site-specific materials and traffic conditions, resulting in a more cost-effective and reliable design.

The software, which is intended to be used in conjunction with the American Association of State Highway and Transportation Officials' (AASHTO) DARwin program, helps highway managers and engineers implement improved design procedures adopted by AASHTO and published in the 1998 Supplement to the AASHTO Guide for Design of Pavement Structures, Part II-Rigid Pavement Design & Rigid Pavement Joint Design. The improved procedures cover such things as consideration of curling and warping, joint spacing design, consideration of slab/base friction, and faulting and corner break prediction.

The spreadsheet includes separate tables for determining accumulated traffic loadings, seasonally adjusted k-values, and depth to rigid layer, as well as for performing corner break and faulting checks. These tables help pavement engineers answer such key questions as:

  • How do I adequately characterize the subgrade support?
  • What is the best base type for existing conditions?
  • What is the optimum joint spacing?
  • Will the pavement fault or have corner breaks?

After starting the program, a user has to enter the concrete properties, base properties, reliability and standard deviation, climatic properties, pavement type, design equivalent single-axle loads, joint spacing, and other information. The program's different tables can then be referenced and design computations made. The software also features a sensitivity analysis function that allows a user to analyze such design parameters as the elastic modulus of the slab or base, base thickness, and modulus of rupture.

The improved design procedures that the software helps implement were initially developed under National Cooperative Highway Research Program project 1-30, "Support Under Concrete Pavements." The procedures were then validated using the design, materials, climate, traffic, and performance data from the LTPP database for general pavement studies (GPS) experiment 3 (jointed plain concrete pavement), GPS-4 (jointed reinforced concrete pavement ) and GPS-5 (continuously reinforced concrete pavement).

The software can be used on any IBM PC that runs Microsoft Office 95 or 97 or Microsoft Excel 7.0. To download the file, go to the LTPP Web site (www.tfhrc.gov/pavement/ltpp/product.htm).

For more information, contact Charlie Churilla at FHWA, 202-493-3143 (fax: 202-493-3161; email: charles.churilla@fhwa.dot.gov).

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Updated: 04/07/2011

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