82pervious concrete have been lower than necessary for required applications, and the freeze-thaw durability of pervious concrete has been suspect.The strength and freeze-thaw durability of pervious concrete mix designs has been addressed in a recently completed study by Kevern et al. (5) and Schaefer et al. (4) who showed that a strong, durable pervious concrete mix design that will withstand hard, wet-freeze environments is possible. Strength and durability are achieved through the use of a small amount of fine aggregate (i.e., concrete sand) or latex admixture, or both, to enhance the particle-to-particle bond in the mix.The National Concrete Pavement Technology Center at Iowa State University is conducting a study entitled "An Integrated Study of Portland Cement Pervious Concrete for Wearing Course Applications." The objective of the study is to conduct a comprehensive research program focused on development of pervious concrete mix designs having adequate strength and durability for wearing course pavements. Mixtures are being designed to possess surface characteristics that reduce noise and enhance skid resistance, while providing adequate removal of water from the pavement surface and structure. It is anticipated that ultimately a range of mix designs will be necessary to meet requirements for wearing course applications. Additionally, constructability issues for wearing course sections are being addressed to ensure that competitive and economical placement of the pervious concrete can be done in the field. Hence, both laboratory and field testing of materials and construction are being conducted, focused on development of a durable wearing course that can be used in highway applications for critical noise, splash and spray, skid resistance, and environmental concerns.To maximize the potential benefits of pervious concrete as an overlay material for noise reduction and skid resistance, the mixture must possess the following properties:• Adequate strength for long-term durability, • Highly durable aggregate for resistance to polishing and freezethaw issues,• Sufficient porosity (around 20% to 25%) to maximize noise reduction and minimize maintenance,• High workability for ease of placement and uniform porosity across the pavement thickness, and• Ability to maintain voids when compaction is applied by the paver for uniform surface porosity.A number of tasks were developed to meet these objectives. This paper describes the construction and performance of a pervious concrete Portland cement pervious concrete (PCPC) has shown great potential to reduce roadway noise, improve splash and spray, and improve friction as a surface wearing course. A study is under way at Iowa State University and the National Concrete Pavement Technology Center to develop mix designs and procedures for PCPC overlays for highway applications. A report is produced on the construction and performance of a PCPC overlay constructed at the Minnesota Road Research Project low-volume roadway test facility to determine the effectiveness of ...

This paper summarizes the construction and early performance assessment of an exposed aggregate surface on a composite pavement test cell (cell 72) at MnROAD. Although exposed aggregate surfaces and composite pavement systems have become extremely popular in Europe, they are a relatively new concept in the United States. The performance of the exposed aggregate surface is compared to that in the two other composite pavement cells at MnROAD: cell 70, hot mix asphalt (HMA) over a recycled aggregate concrete, and cell 71, diamond grind concrete over recycled aggregate concrete. The strength, tire pavement noise (on board sound intensity), sound absorption, friction, texture, and international roughness index were tested. The results suggest that the exposed aggregate concrete surface does not provide significant noise reduction. Innovative diamond grinding of composite pavements might be beneficial for noise reduction. Exposed aggregate surfacing can provide more than adequate friction for driver safety, but it does not show any improvement relative to typical HMA or diamond ground surfaces. Exposed aggregate surfaces have a texture (or mean profile depth) similar to that of traditional diamond ground surfaces but might be detrimental to the ride quality. Continued monitoring of these test cells will aid the development of a wide understanding of exposed aggregate surfaces and composite pavements needed for more effective design and accurate service life models.

This paper compares pavement texture measurements from a three-dimensional (3-D) line-laser scanner and from a two-dimensional (2-D) spot-laser circular track (CT) meter to determine whether correlations exist between their texture parameters. Measurements with the two devices were taken simultaneously on pavements at the Minnesota Department of Transportation MnROAD test facilities. The 3-D texture heights were decomposed by using a discrete wavelet transform to separate microtexture from macrotexture. Macrotexture parameters from the two devices were analyzed. A linear relationship, with an R2 value of .94, was found between the 2-D mean profile depth and the 3-D digitally simulated mean texture depth. Similarly, the R2 value was .98 between the 2-D root mean square roughness and the 3-D root mean square deviation. These correlations are essential and can be used by road agencies to predict texture indexes between 2-D and 3-D measurements for data comparison or quality assurance when equipment is of different dimensions.

Development of a quiet diamond grinding configuration commenced in an initial laboratory effort at Purdue University, followed by research iterations from 2007 to 2010 at the pavement test track research facility (MnROAD) of the Minnesota Department of Transportation (DOT). This paper catalogues the stages in the development and deployment of the Next Generation Concrete Surface (NGCS) from the configuration development at MnROAD, coupled with the simultaneous development of a tire–pavement noise predictive model deployed on Interstate 94 near Saint Cloud, Interstate 35 in Duluth, and Interstate 394 in Minneapolis, Minnesota. NGCS in these projects caused noise reduction of 3 to 6 dB, representing 50% to 75% sound intensity reduction. Diamond grinding was performed on the preexisting textures: burlap drag on Interstate Highway 94 near Saint Cloud, transverse tining on Interstate Highway 35 in Duluth, and Ultra-Thin Bonded Wearing Course (UTBWC) on Interstate 394, Minnesota DOT exceeded the goal of not increasing the pregrind tire–pavement noise level by these rehabilitations. The predictive tire–pavement interaction noise model was validated in these deployments, including on Interstate 394, where the full acoustic benefit of NGCS had been attenuated by the anomalous effect of undulations reminiscent of the previous concrete–UTBWC interface, which had inadvertently conferred a background configuration to the new diamond-ground surface.

Minnesota Department of Transportation (MnDOT) has studied pavement performance associated with various interventions in the road network. In this study, unbonded overlay, a major concrete pavement intervention known for its long service life, was examined. Curve fitting was performed, including a comparison of the current decay curves with previous patterns toward a default performance curve, stepwise regression to identify performance variables associated with and predictive of remaining service life (RSL), and reliability (Weibull) analysis to examine the reliability and other performance characteristics of unbonded overlay in the Minnesota network. Reliability analysis resulted in a RSL (scale parameter) of 36 years, which was reasonably consistent with the 35.5 year RSL derived from the MnDOT Highway Pavement Management Analysis (HPMA). It also provided evidence that the unbonded overlay displays an end-of-life failure pattern as well as a 7-year threshold time to failure (location parameter). MnDOT’s sigmoidal decay model predicted the same expected service life (35.5 years) as did the Weibull analysis process (35.8 years). Stepwise linear regression showed a positive correlation between the time from the most recent rehabilitation (TTR_MR) and RSL. The other explanatory variables including RQI_Spike and time from original construction to intervention (TTR) were found to be non-significant in the prediction of RSL.