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NRMCA Highlights Changes to ACI Parking Lot Guide

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The American Concrete Institute (ACI) recently published the ACI PCR-330-21 Commercial Concrete Parking Lots and Site Paving Design and Construction GuideThe publication of this document in conjunction with the ACI 330.2R-17 Guide for the Design and Construction of Concrete Site Paving for Industrial and Trucking Facilities replaces the ACI 330R-08 guide. By separating the old document into two documents based on the loadings, it allows each to focus on the aspects that are most relevant for that type of development. There are pieces of an industrial design that are not necessary for low- to medium-volume parking lots and vise versa. 

Some of the changes noted in the ACI 330-21 guide include:

  • Pavement thicknesses are calculated by;
  • Revised descriptions and traffic category classifications;
  • Reduced modulus of subgrade reaction (k), Modulus of Rupture (MOR) and truck frequency input values;
  • Elimination of dowels (refers users to ACI 330.2R-17); and
  • Additional sections on fiber reinforced concrete.

NRMCA incorporates these two ACI guides for parking lot designs when preparing recommendations for projects submitted through NRMCA’s Design Assistance Program (DAP). If you have a project and are looking for a concrete design, review of a design or specification, contact your Local Paving representative or submit project information to the website.

For more information, contact Amanda Hult at


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