Performance Factors and Quality Control/Quality Assurance for Porous Pavements

Open-graded hot mixes have been used as road surfaces in Oregon since 1978. Since 1989, they have been used on all Interstate and primary highways in western Oregon; they are used less extensively in eastern Oregon. The Oregon Department of Transportation (ODOT) has pay-adjustment factors for dense-graded mixes based on an evaluation of constituents, including asphalt content, gradation, compaction, and moisture content. As a part of a larger research effort, a survey was administered to various national and international agencies inquiring about their knowledge of and experience with porous pavements. Administration of this survey was sponsored by ODOT; the purpose of the larger research effort was to develop an improved specification for porous pavements that would contain pay incentives and disincentives. Findings from this survey are reported. Of the 28 individuals contacted, responses were received from 24, providing an 86 percent response rate. Because this study was conducted to determine appropriate pay factors for open-graded mixtures, the survey was designed to learn about how other agencies were dealing with specifications and adjustment factors for porous pavements. The findings from the survey are presented with respect to (a) the respondents’ experiences with construction of open-graded asphalt during the past 5 years, (b) the factors that contribute most to the performance of open-graded mixes, (c) the most common types of failures for these mixes, (d) the primary causes of failures of the various types, and (e) the use of specifications that contain provision for pay adjustment.