Evolution of Design Practice at the Iowa State Highway Commission for the Determination of Peak Discharges at Bridges and Culverts, 1971

This paper carries the rather weighty title of "Evolution of Design Practice at the Iowa State Highway Commission for the Determination of Peak Discharges at .Bridges and Culverts." Hopefully, this evolving process will lead to a more precise definition of a peak rate of runoff for a selected recurrence interval at a particular site. In this paper the author will relate where the Highway Commission has been, is now, and will be going in this art of hydrology. He will then offer some examples at a few sites in Iowa to illustrate the use of the various methods. Finally, he will look ahead to some of the pitfalls still lying in wait for us.

Review of Geometric Design Criteria and Lighting Design Criteria, 1968

The investigations for this report were initiated in October, 1967, to perform the following: l. Review the current Iowa State Highway Commission roadway geometric design standards and criteria for conformance with national policies and recent research findings with special attention to high way safety. 2. Review the current Iowa State Highway Commission roadway lighting design standards and criteria for conformance with national policies and recent research findings with special attention to high way safety

Technology Transfer of As-Built and Preliminary Surveys Using GPS, Soft Photogrammetry, and Video Logging, 2002

This research involved two studies: one to determine the local geoid to obtain mean sea level elevation from a global positioning system (GPS) to an accuracy of ±2 cm, and the other to determine the location of roadside features such as mile posts and stop signs for safety studies, geographic information systems (GIS), and maintenance applications, from video imageries collected by a van traveling at traffic speed.

Development of a Mix Design Process for Cold-in-Place Rehabilitation Using Foamed Asphalt, December 2005

Report by Iowa Department of Transportation about pavements materials.

Dowel Bar Optimization: Phases I and II, October 2001

America’s roadways are in serious need of repair. According to the American Society of Civil Engineers (ASCE), one-third of the nation’s roads are in poor or mediocre condition. ASCE has estimated that under these circumstances American drivers will sacrifice $5.8 billion and as many as 13,800 fatalities a year from 1999 to 2001 ( 1). A large factor in the deterioration of these roads is a result of how well the steel reinforcement transfers loads across the concrete slabs. Fabricating this reinforcement using a shape conducive to transferring these loads will help to aid in minimizing roadway damage. Load transfer within a series of concrete slabs takes place across the joints. For a typical concrete paved road, these joints are approximately 1/8-inch gaps between two adjacent slabs. Dowel bars are located at these joints and used to transfer load from one slab to its adjacent slabs. As long as the dowel bar is completely surrounded by concrete no problems will occur. However, when the hole starts to oblong a void space is created and difficulties can arise. This void space is formed due to a stress concentration where the dowel contacts the concrete. Over time, the repeated process of traffic traveling over the joint crushes the concrete surrounding the dowel bar and causes a void in the concrete. This void inhibits the dowel’s ability to effectively transfer load across the joint. Furthermore, this void gives water and other particles a place to collect that will eventually corrode and potentially bind or lock the joint so that no thermal expansion is allowed. Once there is no longer load transferred across the joint, the load is transferred to the foundation and differential settlement of the adjacent slabs will occur.

Determination and Evaluation of Alternative Methods for Managing and Controlling Highway-Related Dust Phase II—Demonstration Project, June 2005

The State of Iowa currently has approximately 69,000 miles of unpaved secondary roads. Due to the low traffic count on these unpaved o nts as ng e two dust ed d roads, paving with asphalt or Portland cement concrete is not economical. Therefore to reduce dust production, the use of dust suppressants has been utilized for decades. This study was conducted to evaluate the effectiveness of several widely used dust suppressants through quantitative field testing on two of Iowa’s most widely used secondary road surface treatments: crushed limestone rock and alluvial sand/gravel. These commercially available dust suppressants included: lignin sulfonate, calcium chloride, and soybean oil soapstock. These suppressants were applied to 1000 ft test sections on four unpaved roads in Story County, Iowa. Tduplicate field conditions, the suppressants were applied as a surface spray once in early June and again in late August or early September. The four unpaved roads included two with crushed limestone rock and two with alluvial sand/gravel surface treatmewell as high and low traffic counts. The effectiveness of the dust suppressants was evaluated by comparing the dust produced on treated and untreated test sections. Dust collection was scheduled for 1, 2, 4, 6, and 8 weeks after each application, for a total testiperiod of 16 weeks. Results of a cost analysis between annual dust suppressant application and biennial aggregate replacement indicated that the cost of the dust suppressant, its transportation, and application were relatively high when compared to that of thaggregate types. Therefore, the biennial aggregate replacement is considered more economical than annual dust suppressant application, although the application of annual dust suppressant reduced the cost of road maintenance by 75 %. Results of thecollection indicated that the lignin sulfonate suppressant outperformed calcium chloride and soybean oil soapstock on all four unpavroads, the effect of the suppressants on the alluvial sand/gravel surface treatment was less than that on the crushed limestone rock, the residual effects of all the products seem reasonably well after blading, and the combination of alluvial sand/gravel surface treatment anhigh traffic count caused dust reduction to decrease dramatically.

Development of In-Situ Detection Methods for Materials-Related Distress (MRD) in Concrete Pavements, July 2003

The purpose of this research was to summarize existing nondestructive test methods that have the potential to be used to detect materials-related distress (MRD) in concrete pavements. The various nondestructive test methods were then subjected to selection criteria that helped to reduce the size of the list so that specific techniques could be investigated in more detail. The main test methods that were determined to be applicable to this study included two stress-wave propagation techniques (impact-echo and spectral analysis of surface waves techniques), infrared thermography, ground penetrating radar (GPR), and visual inspection. The GPR technique was selected for a preliminary round of “proof of concept” trials. GPR surveys were carried out over a variety of portland cement concrete pavements for this study using two different systems. One of the systems was a state-of-the-art GPR system that allowed data to be collected at highway speeds. The other system was a less sophisticated system that was commercially available. Surveys conducted with both sets of equipment have produced test results capable of identifying subsurface distress in two of the three sites that exhibited internal cracking due to MRD. Both systems failed to detect distress in a single pavement that exhibited extensive cracking. Both systems correctly indicated that the control pavement exhibited negligible evidence of distress. The initial positive results presented here indicate that a more thorough study (incorporating refinements to the system, data collection, and analysis) is needed. Improvements in the results will be dependent upon defining the optimum number and arrangement of GPR antennas to detect the most common problems in Iowa pavements. In addition, refining highfrequency antenna response characteristics will be a crucial step toward providing an optimum GPR system for detecting materialsrelated distress.

Enlgish and Spanish Terms for Concrete Paving Workers, November 2004

Proper storage practices are critical to protect materials from intermingling, contamination, or degradation, and to maintain consistent aggregate gradation throughout a project. Concrete Paving Workforce Reference no.4. Spanish version.

Concrete Materials Storage, Mixing and Delivery, November 2004

Proper storage practices are critical to protect materials from intermingling, contamination, or degradation, and to maintain consistent aggregate gradation throughout a project. Concrete Paving Workforce Reference no.1

Concrete Pavement Joint Sawing, Cleaning, and Sealing, November 2004

Proper storage practices are critical to protect materials from intermingling, contamination, or degradation, and to maintain consistent aggregate gradation throughout a project. Concrete Paving Workforce Reference no.3

Portland Cement Concrete Patching Techniques vs. Performance and Traffic Delay, January 2004

Standards for the construction of full-depth patching in portland cement concrete pavement usually require replacement of all deteriorated based materials with crushed stone, up to the bottom of the existing pavement layer. In an effort to reduce the time of patch construction and costs, the Iowa Department of Transportation and the Department of Civil, Construction and Environmental Engineering at Iowa State University studied the use of extra concrete depth as an option for base construction. This report compares the impact of additional concrete patching material depth on rate of strength gain, potential for early opening to traffic, patching costs, and long-term patch performance. This report also compares those characteristics in terms of early setting and standard concrete mixes. The results have the potential to change the method of Portland cement concrete pavement patch construction in Iowa.

Implementing the Mechanistic-Empirical Pavement Design Guide: Technical Report, May 2005

With the release of the new Mechanistic-Empirical Pavement Design Guide (MEPDG), pavement design has taken a “quantum” leap forward. The current 1993 design guide is solidly based on the empirical interpretation of the results of the 1960 American Association of State Highway and Transportation Officials (AASHTO) Road Test. This report seeks to outline the technical aspects of the new MEPDG. Full detail is essentially impossible and impractical, since the release of the MEPDG was accompanied by eighteen volumes of technical justification and background. Consequently, this report seeks only to provide a potential user with a practical understanding of the workings of the new guide, with only sufficient technical depth to aid in understanding.

Sustainable Development and Concrete Technology, May 2004

For a variety of reasons, the concrete construction industry is not sustainable. First, it consumes huge quantities of virgin materials. Second, the principal binder in concrete is portland cement, the production of which is a major contributor to greenhouse gas emissions that are implicated in global warming and climate change. Third, many concrete structures suffer from lack of durability which has an adverse effect on the resource productivity of the industry. Because the high-volume fly ash concrete system addresses all three sustainability issues, its adoption will enable the concrete construction industry to become more sustainable. In this paper, a brief review is presented of the theory and construction practice with concrete mixtures containing more than 50% fly ash by mass of the cementitious material. Mechanisms are discussed by which the incorporation of high volume of fly ash in concrete reduces the water demand, improves the workability, minimizes cracking due to thermal and drying shrinkage, and enhances durability to reinforcement corrosion, sulfate attack, and alkali-silica expansion. For countries like China and India, this technology can play an important role in meeting the huge demand for infrastructure in a sustainable manner.

Concrete Paving Notes Construction No.1, 2005

This booklet will help developers, consultants, and engineers planning concrete pavement construction projects, superintendents and supervisors who want a basic training aid and reference, and crew members new to the concrete paving industry. It provides a general description of current concrete pavement construction practices, from establishing preconstruction control mechanisms to sealing joints. It also provides a quick troubleshooting reference.

Long-term Plan for Concrete Pavement Research and Technology: The CP Road Map, November 2004, Volume 1 of 2

An Iowa State University–led team facilitated development of the CP Road Map. They developed a database of existing research. They gathered input, face to face, from the highway community. They identified gaps in research that became the basis for problem statements, which they organized into a cohesive, strategic research plan.