Friday Facts, February 25, 2011, Vol. 90

Bureau of Nutrition and Health Promotion part of the Iowa Department of Public Health produces of weekly newsletter about the Iowa WIC Program for the State of Iowa citizen.

Evaluation of Asphalt Mix Permeability, MLR-90-2, 1992

Efforts to eliminate rutting on the Interstate system have resulted in 3/4 in. aggregate mixes, with 75 blow Marshall, 85% crushed aggregate mix designs. On a few of these projects paved in 1988-1989, water has appeared on the surfaces. Some conclusions have been reached by visual on-sight investigations that the water is coming from surface water, rain and melting snow gaining entry into the surface asphalt mixture, then coming back out in selected areas. Cores were taken from several Interstate projects and tested for permeability to investigate the surface water theory that supposedly happens with only the 3/4 in. mixtures. All cores were of asphalt overlays over portland cement concrete, except for the Clarke County project which is full depth AC. The testing consisted of densities, permeabilities, voids by high pressure airmeter (HPAM), extraction, gradations, AC content, and film thicknesses. Resilient modulus, indirect tensile and retained strengths after freeze/thaw were also done. All of the test results are about as expected. Permeabilities, the main reason for testing, ranged from 0.00 to 2.67 ft per day and averages less than 1/2 ft per day if the following two tests are disregarded. One test on each binder course came out to 15.24 ft/day, and a surface course at 13.78 ft/day but these are not out of supposedly problem projects.

Permeability of Granular Subbase Materials, MLR-90-4, 1991

The purpose of this research was to evaluate the materials Iowa uses as a granular subbase and to determine if it provides adequate drainage. Numerous laboratory and in-situ tests were conducted on the materials currently being used in Iowa. The follow conclusions can be made based on the test results: 1. The crushed concrete that is used as a subbase material has a relatively low permeability compared to many other materials used by other states. 2. Further research and tests are needed to find the necessary parameters for crushed concrete to make sure it is providing its optimum drainage and preventing premature damage of the pavement. 3. We have definitely made improvements in drainage in the past few months, but there are many areas that we can improve on that will increase the permeability of this material and insure that the pavement system is safe from premature damage due to water. The current gradation specification for granular subbase material at the start of this study was: Sieve # % Passing 1” 100 #8 10-35 #50 0-15 #200 0-6

Laboratory Evaluation of Polymer and Multi-Grade Asphalt Binders, MLR-90-5, 1992

A number of claims have been made that polymer modified asphalt cements, multi-grade asphalt cements, and other modifications of the liquid asphalt will prevent rutting and other deterioration of asphalt mixes, thereby, extending the service life of asphalt pavements. This laboratory study evaluates regular AC-20 asphalt cement, PAC-30 polymer modified asphalt cement and AC-10-30 multi-grade asphalt cement. PAC-30 was also evaluated with 15% Gilsonite and 15% Witcurb in a 75% crushed stone - 25% sand mix. These mixtures were evaluated for all Marshall properties along with indirect tensile, resilient modulus, and creep resistance.

Webster County, Township 90 North Range 28 West

Des Moines River Plat Maps.

Crushed Stone Granular Surfacing Materials, HR-2046 and MLR-90-07, 1990

This project included the following tasks: (1) Preparation of a questionnaire and survey of all 99 Iowa county engineers for input on current surfacing material practice; (2) County survey data analysis and selection of surfacing materials gradations to be used for test road construction; (3) Solicitation of county engineers and stone producers for project participation; (4) Field inspection and selection of the test road; (5) Construction of test road using varying material gradations from a single source; and (6) Field and laboratory testing and test road monitoring. The results of this research project indicate that crushed stone surfacing material graded on the fine side of Iowa Department of Transportation Class A surfacing specifications provides lower roughness and better rideability; better braking and handling characteristics; and less dust generation than the coarser gradations. It is believed that this material has sufficient fines available to act as a binder for the coarser material, which in turn promotes the formation of tight surface crust. This crust acts to provide a smooth riding surface, reduces dust generation, and improves vehicle braking and handling characteristics.

Stabilization Procedures to Mitigate Edge Rutting for Granular Shoulders - Phase II, TR-591, 2011

A multifaceted investigation was undertaken to develop recommendations for methods to stabilize granular road shoulders with the goal of mitigating edge ruts. Included was reconnaissance of problematic shoulder locations, a laboratory study to develop a method to test for changes in granular material stability when stabilizing agents are used, and the construction of three sets of test sections under traffic at locations with problematic granular shoulders. Full results of this investigation are included in this report and its appendices. This report also presents conclusions and recommendations based on the study results.

Final Report (SPR Project 90-00-RB10-012) on the Maintenance Asset Management Project Phase I, 2012

This project resulted in the development of a proof of concept for a features inventory process to be used by field staff. The resulting concept is adaptable for different asset classes (e.g. culverts, guardrail) and able to leverage existing DOT resources such as the videolog and LRS and our current technology platforms including Oracle and our GIS web infrastructure. The concept examined the feasibility of newly available technologies, such as mobile devices, while balancing ease of use in the field. Implementation and deployment costs were also important considerations in evaluating the success of the project. These project funds allowed the pilot to address the needs of two DOT districts. A report of findings was prepared, including recommendations for or against full deployment of the pilot solution.

Final Report (SPR Project 90-00-RB10-012) on the Maintenance Asset Management Project Phase II, 2013

This project resulted in the development of a proof of concept for a features inventory process to be used by field staff. The resulting concept is adaptable for different asset classes (e.g. culverts, guardrail) and able to leverage existing DOT resources such as the videolog and LRS and our current technology platforms including Oracle and our GIS web infrastructure. The concept examined the feasibility of newly available technologies, such as mobile devices, while balancing ease of use in the field. Implementation and deployment costs were also important considerations in evaluating the success of the project. These project funds allowed the pilot to address the needs of two DOT districts. A report of findings was prepared, including recommendations for a full deployment of a field data collection.