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Evaluation of Full Depth Asphalt Pavements - Interim Report

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Date Created
1977
Description
This research investigation, conducted by the Physical Research Unit of the Minnesota Department of Transportation, began in 1971 to learn more about the behavior of Full-Depth Asphalt pavements. The investigation has 26 test sections, each 1200 feet (365.8m) long, of a variety of thicknesses, on a variety of soils. The thicknesses range from approximately five inches (12.7 cm) to 17.5 inches (44.5 cm) and soil types include AASHO soil classification A-2-4's. A-3's. A-4's. A-6's and A-7-6's. These soils include a stabilometer R value range of 5 to 75. The major portions of the research work on this investigation consisted of Benkelman Beam measurements on the zest sections at 50 foot (15.2 m) intervals, taken weekly throughout rh2 spring, bi-weekly throughout the summer and monthly into the fall. The temperature of the upper 1.5 inches (3.8 cm) of the mat was measured each time the Benkelman Beam deflections were taken. These data were then used to determine the effect the temperature and the season had on the deflections and also created a set of correction factors to apply to the measured deflections to adjust the deflections to an 80‘F (26.70C) peak season deflection. The peak season 80‘F (26.7C) mat temperature deflection was then taken to be the standard deflection for each of he test sections. These standard deflections were then compared to the deflections of aggregate base pavements and a relationship was developed between the Full-Depth thickness and the granular equivalency of an equivalent deflection aggregate base pavement. That relationship was then used to develop a Full-Depth bituminous pavement design chart which is the deflection equivalent of the flexible pavement design chart currently in use by Mn/DOT. The serviceability of the Full-Depth has also been monitored in terms of pavement roughness, rut depth and surface condition. The serviceability of the rest sections have nor changed enough to adequately estimate the performance of the test sections at the rime of this report.

Bio-Material Maintenance Treatments

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Date Created
2023-09
Report Number
NRRA202306
Description
Asphalt pavements deteriorate from temperature cycling, moisture, oxidation, and loading-related distresses. Pavement preservation is critical in maintaining the functional and structural integrity of roads and extending pavement life. Surface treatments can prevent or restore the aging effects by rejuvenating and/or sealing the pavement’s surface, limiting further damage, and restoring its flexibility. This collaborative study of MnDOT, the National Road Research Alliance (NRRA), and Iowa State University investigates the efficacy of fog seal/bio-fog seal topical treatments based on soy-derived rejuvenators, epoxidized soybean oil (SESO), and BioMAG, which contains SESO and the biopolymer poly(acrylated epoxidized high oleic soybean oil) (PAEHOSO). Each topical treatment is applied at three locations in different asphalt binder grades to provide a comprehensive approach to their impacts on the dry time, reflectivity, friction, and permeability of the pavement course. It is observed that the bio-fog seal treatments improve the skid resistance of the pavement, do not affect the reflectivity of pavement markings, and are able to restore the stiffness of the asphalt mixtures. Additionally, the fog seals show fast setting and curing and allows the road to be open to traffic in less than 30 minutes.

Influence of Test Method Variables on Mn/ROAD Hot Mix Asphalt Mixture Test Results

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Date Created
1997-01
Report Number
P2000-03
Description
At the Minnesota Road Research Project (Mn/ROAD), asphalt concrete mixtures were used to evaluate both warm and cold temperature material properties with selected text methods and a wide range of testing parameters. These parameters were selected to approximate different levels of environmental conditions, traffic speeds, traffic loads, and, in certain cases, confining pressures. The underlying theories used to calculate stress and strain from various loading configurations also were rigorously evaluated to determine the appropriateness of comparing results from one testing configuration to another. Mn/ROAD mixtures were evaluated as the first step in linking laboratory measurements and test method selection to live traffic pavement responses and performance. A comparison of axial and diametral testing using harmonic loading showed that experimental results did not agree with theory. That is, the complex deviatoric modulus determined for diametral testing should have been less than the Young's modulus determined from testing axially loaded samples. This was not the case. This suggested that a further examination of the sample instrumentation, testing variability, and the possibility of anisotropic mixture behavior due to particle orientation during compaction are needed to resolve these differences. Other findings indicated that the influence of load duration is minimized as the test temperature decreases, there was little influence in rest period times in repeated loading tests on modulus, and confining pressure only had a significant influence on modulus above about room temperature.

The Effect of Voids in Mineral Aggregate (VMA) on Hot Mix Asphalt Pavements

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Date Created
1999
Report Number
2000-13
Description
This research project investigates the level of Voids in the Mineral Aggregate (VMA) in Minnesota paving projects. Researchers analyzed 10 paving projects from 1996 to determine if a VMA decrease occurred, the magnitude of the decrease, and the potential causes of the decrease. Potential causes include the generation of fines, high-production temperatures, and long storage or cure times. Three of the 10 projects had a VMA decrease of 1.9 or more. These three projects also had the highest plant temperatures and fairly long storage times, which makes increased asphalt absorption a likely cause of the VMA decrease. Five projects showed a moderate drop in VMA. Most had some increases in fines, and some had moderately high plant temperatures and storage times. The two projects with little or no change in VMA had very little change in gradation, and moderate to low plant temperatures and storage times.

Cold In-Place Recycling Literature Review and Preliminary Mixture Design Procedure

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Date Created
2000
Report Number
2000-21
Description
This research report summarizes the results of a project to assist in the development of a mix design procedure for partial depth cold in-place recycling (CIR) mixtures. An asphalt pavement rehabilitation method, CIR involves mixing reclaimed asphalt pavement (RAP), water, and a recycling agent in place and without heat. During the construction of partial depth cold in-place recycling, one type of CIR, milling is done at depths of 50 to 100 mm (2 to 4 in.) with the resulting layer frequently used as base course. In this project, researchers mixed RAP from Trunk Highways 23, 59, and 71, and County State Aid Highway 5 with emulsions CSS-1, HFMS-2s, and HRMS-2p. After preparing specimens with a gyratory compactor and Marshall hammers, researchers tested the specimens for bulk specific gravity, maximum specific gravity, and air voids. In addition, indirect tensile strength tests were used to evaluate the effects of changes in curing periods and compactive effort on CIR mixtures. Researchers concluded that the asphalt content in the RAP affects the emulsion to be added in the CIR mixture; that emulsion HFMS-2p resulted in the lowest overall voids; and that the gyratory compactor produced the best specimens for testing and evaluation.

Methods and Materials for Reducing Crack Reflectance (1985)

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Date Created
1985-01
Report Number
84-09
Description
This study was initiated to study methods, procedures and/or materials that may reduce premature pavement failures of asphaltic concrete overlays on PCC pavement caused by excessive reflective cracking. Methods included in this study were reducing the existing PCC pavement panel size by saw cutting, full coverage fabrics, strip fabrics and Rubber-Asphalt Interlayer as a Stress Absorbing Membrane Interlayer (SAMI). No material or method was found that would totally eliminate reflective cracking, Reducing the existing PCC pavement panel size and the use of the Rubber-Asphalt Interlayer were the two procedures that provided the best results.

The Use of Asphalt-rubber Products in Minnesota

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Date Created
1989-09
Report Number
89-06
Description
This report is a compilation of completed and soon to be completed asphalt: rubber studies undertaken by the Minnesota Department of Transportation (MN/DOT). The goals of each study vary with the manner in which the asphalt-rubber was utilized. Asphalt-rubber has been utilized in hopes of limiting reflective cracking by means of a stress absorbing membrane or a stress absorbing membrane interlayer. Using asphalt- rubber in a dense graded bituminous mixture was also attempted with the intent to limit reflective cracking while also resisting stripping due to greater film thickness rn1 the aggregate and greater impermeability to water. The Plus-Ride(TM) system of using granular rubber and a gap graded aggregate in a plant-mixed bituminous surface was employed in hopes of creating a self-deicing pavement. The results from these test projects vary from site to site but overall the Department: remains cautiously optimistic that asphalt-rubber can be an effective tool in pavement maintenance and reconstruction.

Flexible Slurry System

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Date Created
2007
Description
The flexible slurry system is a mixture of emulsified asphalt, high quality crushed aggregate, and water. Depending upon the design, flexible slurry can be used in place of a blade leveling course prior to bituminous overlay or as a wear course. Flexible slurry is constructed using a micro surfacing machine, but is less brittle than a usual micro surface mixture. Historically Minnesota has used one type of emulsified asphalt (PG 64-22); but recent experimentation with binder grades shows that enhanced rutting and cracking performance is possible. Low speed traffic can aid in the curing and consolidation of flexible slurries.