UC Pavement Research Center
Li, Hui, David Jones, Rongzong Wu, John T. Harvey (2014) Development and HVS Validation of Design Tables for Permeable Interlocking Concrete Pavement: Final Report. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-14-34
This report details the research undertaken to develop revised design tables for permeable interlocking concrete pavement using a mechanistic-empirical design approach. The study included a literature review, field testing of existing projects and test sections, estimation of the effective stiffness of each layer in permeable interlocking concrete pavement structures, mechanistic analysis and structural design of a test track incorporating three different subbase thicknesses (low, medium, and higher risk), tests on the track with a Heavy Vehicle Simulator to collect performance data to validate the design approach using accelerated loading, refinement and calibration of the design procedure using the test track data, development of a spreadsheet based design tool, and development of revised design tables using the design tool. Key findings from the mechanistic analysis include:
- Higher shear stress/strength ratios at the top of the subgrade, which equate to a higher risk of rutting in the subgrade, require thicker subbase layers, as expected.
- An increase in the stiffness of the surface layer reduces the required subbase layer thickness to achieve the shear stress/strength ratio. However, the effect of the surface layer stiffness on overall pavement performance is not significant due to the relatively low thickness of the pavers (80 mm) and the reduced interlock between them compared to pavers with sand joints.
- For the same shear stress/strength ratio at the top of the subbase, an increase in the stiffness of the subbase layer reduces the required thickness of that subbase layer, especially when the subgrade has a low stiffness.
- For the same shear stress/strength ratio at the top of the subgrade, wet conditions require thicker subbase layers compared to the dry condition, confirming that wet conditions are the most critical condition for design.
The study also developed new example design tables that are based on either a specific number of target days with standing water in the subbase or on a range of days. The tables use a similar format to that currently used in the ICPI Permeable Interlocking Concrete Pavements guideline. The minimum design thicknesses required to prevent subgrade rutting that are proposed in the new tables do not differ significantly from those in the current ICPI guide, and are mostly less conservative. Designs for a specific set of project circumstances can be undertaken using the same Excel® spreadsheet-based design tool used to develop the tables in conjunction with the hydrological design procedures provided in the ICPI guide.*Note: Version 1.2 includes the corrected term “drained test” in the first paragraph of Section 7.2, and new sets of proposed example design tables in Chapter 9. The first set of tables has additional columns for days with water in the subbase. The second set has a range of days, instead of a single day value.
Keywords: permeable interlocking concrete pavement, permeable pavement, mechanistic-empirical design, accelerated pavement testing
UC Pavement Research Center Research Report UCPRC-RR-2014-04.2