Concrete parking lots have many advantages over asphalt parking lots and are easy to build if they are designed properly. The ACI 330 Guide for the Design and Construction of Concrete Parking Lots was developed specifically for parking lots as opposed to the 1993 AASHTO Guide for Pavement Design, which was developed for highway pavements. The ACI 330 accounts for specific traffic loads, soil characteristics, and the strength of concrete to determine the required concrete thickness. For more information regarding the benefits of concrete parking lots, as well as tips on how to build them, please see our videos on those topics.
Standard duty concrete parking lots can be designed to be paved directly on compacted subgrade and do not require an aggregate base for drainage or structural support. For unstable, expansive, or other problem soils, the most effective treatment is to stabilize the soil by mixing in cement to a minimum of 6″ deep and compacting to specified density.
An aggregate base should be used in heavy-duty areas where there is potential for either faulting or pumping of the subgrade to occur. Pumping occurs when heavy loads traveling at high speeds cross a joint causing a large deflection that ejects or “pumps” subgrade material from beneath the slab. Since light loads do not cause large enough deflections to cause pumping, aggregate base is unnecessary for standard duty pavements.
After the subgrade soils are classified by characterization and support value, the pavement is ready to be designed. When designing the pavement for a parking lot construction, the concrete strength should be between 3,000 and 4,000 psi, typically corresponding to a flexural strength of 550-600 psi.
The parking lot is also classified by anticipated traffic load type. The ACI 330 procedure groups the design traffic into 4 categories: Categories A, B, C, D which are based on specific axle loads distributions. For example, Category A is appropriate for light duty parking lots or passenger vehicles, while Category D is for distribution centers and trucks stops.
Having completed the previous steps, the ACI 330 manual provides an easy to use table listing the adequate pavement thickness for these design criteria.
Prior to beginning construction, a joint layout plan should be developed by the Project Engineer. This plan details the location and types of joints to be constructed. Most of the joints in an unreinforced concrete parking lot will be contraction joints made by saw-cuts.
Concrete can be constructed at the same cost of asphalt, with lower ownership costs when designed properly through the use of the ACI 300.
To learn more about how to apply the ACI 330 design procedure to your project, please contact your CEMEX representative, or you can reach us at:
1-855-CX-BUILD (1-855-292-8453)
cemex.solutions@cemex.com
Please visit us at: https://www.cemexusa.com.
Post time: Jun-19-2017