Superpave Mix Designs for Low Volume Roads, Construction Report, TR-414, 2001

Most research current to the time of these projects was focused on use of Superpave mix designs on higher volume roads. Low volume roads have different requirements in terms of mix design, aggregate types, aggregate sources and project budgets. The purpose of this research was to determine if the Superpave mix design strategy for low volume roads was practical and economical. Eight projects were selected in five counties. The projects were completed in the summer of 1998. Performance evaluation of the resulting pavements was carried out annually. There was no significant increase in costs related to the use of Superpave. Nor were there any significant construction issues. There were some differences noted in placement and compaction in the field, but these were not serious.

Evaluation of Gateway and Low-Cost Traffic-Calming Treatments for Major Routes in Small, Rural Communities, TR-523, 2007

Many rural communities have developed around highways or major county roads; as a result, the main street through small rural communities is often part of a high-speed rural highway. Highways and county roads are characterized by high speeds outside the city limits; they then transition into a reduced speed section through the rural community. Consequently, drivers passing through the community often enter at high speeds and maintain those speeds as they travel through the community. Traffic calming in small rural communities along major roadways is common in Europe, but the U.S. does not have experience with applying traffic-calming measures outside of major urban areas. The purpose of the project was to evaluate traffic-calming treatments on the major road through small Iowa communities using either single-measure low-cost or gateway treatments. The project was partially funded by the Iowa Highway Research Board (IHRB). The focus of the IHRB portion was to evaluate single-measure, low-cost, traffic-calming measures that are appropriate to major roads through small rural communities. Seven different low-cost traffic treatments were implemented and evaluated in five rural Iowa communities. The research evaluated the use of two gateway treatments in Union and Roland; five single-measure treatments (speed table, on-pavement “SLOW” markings, a driver speed feedback sign, tubular markers, and on-pavement entrance treatments) were evaluated in Gilbert, Slater, and Dexter.

Ultrathin Portland Cement Concrete Overlay Extended Evaluation, Construction Report, TR-432, 2000

In recent years, ultra-thin whitetopping (UTW) has evolved as a viable rehabilitation technique for deteriorated asphalt cement concrete (ACC) pavement. Numerous UTW projects have been constructed and tested, enabling researchers to identify key elements contributing to their successful performance. These elements include foundation support, interface bonding condition, portland cement concrete (PCC) overlay thickness, synthetic fiber reinforcement usage, joint spacing, and joint sealing. The interface bonding condition is the most important of these elements. It enables the pavement to act as a composite structure, thus reducing tensile stresses and allowing an ultra-thin PCC overlay to perform as intended. The Iowa Department of Transportation (Iowa DOT) UTW project (HR-559) initiated UTW in Iowa. The project is located on Iowa Highway 21 between Iowa Highway 212 and U.S. Highway 6 in Iowa County, near Belle Plaine, Iowa. The objective of this research was to investigate the interface bonding condition between an ultra-thin PCC overlay and an ACC base over time, considering the previously mentioned variables. This research lasted for five years, at which time it was extended an additional five years. The new phase of the project was initiated by removing cracked panels existing in the 2-inch thick PCC sections and replacing them with three inches of PCC. The project extension (TR 432) will provide an increased understanding of slab bonding conditions over a longer period, as well as knowledge regarding the behavior of the newly rehabilitated areas. In order to accomplish the goals of the project extension, Falling Weight Deflectometer (FWD) testing will continue to be conducted. Laboratory testing, field strain gage implementation, and coring will no longer be conducted. This report documents the planning and construction of the rehabilitation of HR 559 and the beginning of TR 432 during August of 1999.

An Investigation of Portland Cement Concrete Utilizing 70% Class V Aggregate and 30% Calcareous Coarse Aggregate, R-255, 1973

The main sources of coarse aggregate for secondary slip form paving in Southwest Iowa exhibit undesirable "D" cracking. "D" cracking is a discoloration of the concrete caused by fine, hairline cracks. These cracks are caused by the freezing and thawing of moisture inside the coarse aggregate. The cracks are often hour glass shaped, are parallel to each other, and occur along saw joints. The B-4, a typical secondary mix, utilizes 50% fine aggregate and 50% coarse aggregate. It has been proposed that a concrete mix with less coarse aggregate and more fine aggregate might impede this type of deterioration. The Nebraska Standard 47B Mix, a 70% fine aggregate, and 30% coarse aggregate mix, as used by Nebraska Department of Roads produces concrete with ultimate strengths in excess of 4500 psi but because of the higher cost of cement (it is a six bag per cubic yard mix) is not competitive with our present secondary mixes. The sands of Southwest Iowa generally have poorer mortar strengths than the average Iowa Sand. Class V Aggregate also found in Southwest Iowa has a coarser sand fraction, therefore it has a better mortar strength, but exhibits an acidic reaction and therefore must be·used with limestone. This illustrates the need to find a mix for use in Southwest Iowa that possesses adequate strength and satisfactory durability at a low cost. The purpose of this study is to determine a concrete mix with an acceptable cement content which will produce physical properties similar to that of our present secondary paving mixes.

Characteristics of Chemical Treated Roadway Surfaces, HR-33, 1963

Iowa Highway Commission Project HR-33, "Characteristics of Chemically Treated Roadway Surfaces", was investigated at the Iowa Engineering Experiment Station under Project 375-S. The purpose of the project as originally proposed was to study the physical and chemical characteristics of chemically treated roadway surfaces. All chemical treatments were to be included, but only sodium chloride and calcium chloride treated roadways were investigated. The uses of other types of chemical treatment were not discovered until recently, notably spent sulfite liquor and a commercial additive. Costs of stabilized secondary roads in Hamilton County averaged $4300.00 per mile even though remanent soil-aggregate material was used. The cost of similar roads in Franklin County was $4400.00 per mile. The Franklin County road surfaces were constructed entirely from materials that were hauled to the road site. Costs in Butler County were a little over $3000.00 per mile some eight years ago. Chemical investigations indicate that calcium chloride and sodium chloride are lost through leaching. Approximately 95 percent of the sodium chloride appears to have been lost, and nearly 65 percent of the calcium chloride has disappeared. The latter value may be much in error since surface dressings of calcium chloride are commonly used and have not been taken into account. Clay contents of the soil-aggregate-chemical stabilized roads range from about 6 to ll percent, averaging 8 or 9 percent. The thicknesses of stabilized mats are usually 2 to 4 inches, with in-place densities ranging from 130 to 145 pcf. Generally the densities found in sodium chloride stabilized roads were slightly higher than those found in the calcium chloride stabilized roads.

Recycled Asphalt Pavement Kossuth County Iowa, HR-176, 1982

In 1975, Kossuth County had 492 miles of asphalt pavements, sixty percent of which were between l5 and 20 years old. Many of these roadways were in need of rehabilitation. Normally, asphaltic resurfacing would be the procedure for correcting the pavement deterioration. There are areas within the state of Iowa which do not have Class I aggregate readily available for asphalt cement concrete paving. Kossuth County is one of those areas. The problem is typified by this project. Limestone aggregate to be incorporated into the asphalt resurfacing had to be hauled 53 miles from the quarry to the plant site. The cost of hauling good quality aggregate coupled with the increasing cost of asphalt cement encouraged Kossuth County to investigate the possibility of asphaltic pavement recycling. Another problem, possibly unique to Kossuth County, was the way the original roadways had been constructed. A good clay soil was present under 3 to 4 feet of poorer soil. In order to obtain this good clay soil for subbase construction, the roadway ditches were excavated 1 to 3 feet into the clay soil layer. The resultant roadway tops were several feet above the surrounding farm land and generally less than 26 feet wide. To bring the existing roadway up to current minimum design width, there were two choices: One was to widen the roadway by truck hauling soil and constructing new 4 to 6 foot shoulders. The cost of widening by this method averaged $36,000 per mile in 1975. The other choice was to remove the old pavement and widen the roadway by lowering the grade line. The desire to provide wider paved roadways gave Kossuth County the additional incentive needed to proceed with a pavement recycling project.

Audit report on the North Central Iowa Regional Solid Waste Agency for the year ended June 30, 2013

Audit report on the North Central Iowa Regional Solid Waste Agency for the year ended June 30, 2013

Audit report on the Regional Utility Service Systems Commission for the year ended June 30, 2013

Audit report on the Regional Utility Service Systems Commission for the year ended June 30, 2013

Audit report on America’s Agricultural Industrial Heritage Landscape, Inc., d/b/a Silos and Smokestacks National Heritage Area and Silos and Smokestacks Natural Heritage Area Foundation in Waterloo, Iowa for the years ended December 31, 2013 and 2012

Audit report on America’s Agricultural Industrial Heritage Landscape, Inc., d/b/a Silos and Smokestacks National Heritage Area and Silos and Smokestacks Natural Heritage Area Foundation in Waterloo, Iowa for the years ended December 31, 2013 and 2012

A Computer Based Information System for County Equipment Cost Records, Interim Report, HR-173, 1975

This report describes the work accomplished to date on research project HR-173, A Computer Based Information System for County Equipment Cost Records, and presents the initial design for this system. The specific topics discussed here are findings from the analysis of information needs, the system specifications developed from these findings, and the proposed system design based upon the system specifications. The initial system design will include tentative input designs for capturing input data, output designs to show the output formats and the items to be output for use in decision making, file design showing the organization of information to be kept on each piece of equipment in the computer data file, and general system design explaining how the entire system will operate. The Steering Committee appointed by Iowa Highway Research Board is asked to study this report, make appropriate suggestions, and give approval to the proposed design subject to any suggestions made. This approval will permit the designer to proceed promptly with the development of the computer program implementation phase of the design.

Wind Tunnel Analysis of the Effects of Planting at Highway Grade Separation Structures, HR-202, 1979

Blowing and drifting snow has been a problem for the highway maintenance engineer virtually since the inception of the automobile. In the early days, highway engineers were limited in their capability to design and construct drift free roadway cross sections, and the driving public tolerated the delays associated with snow storms. Modern technology, however, has long since provided the design expertise, financial resources, and construction capability for creating relatively snowdrift free highways, and the driver today has come to expect a highway facility that is free of snowdrifts, and if drifts develop they expect highway maintenance crews to open the highway within a short time. Highway administrators have responded to this charge for better control of snowdrifting. Modern highway designs in general provide an aerodynamic cross section that inhibits the deposition of snow on the roadway insofar as it is economically feasible to do so.

Pavement Instrumentation, HR-293, 1988

The report documents the development and installation of an instrumented pavement on I-80 in Iowa for the purposes of demonstration and answering current pavement questions. Its two primary objectives include documentation of the installation and verification of existing design procedures through monitoring of the continuous traffic stream reactions in the pavement. Some 120 instruments were installed in a forty foot segment of reconstructed pavement. The instruments included concrete strain gages, weldable strain gages on dowels, LVDT-deflection gages and temperature sensors in the concrete and base material. Five tubes were placed under three joints and two midslabs to measure the relative moisture and density at the interface between the pavement and base with atomic equipment. The instruments were placed ahead of the paving and over 92% of the instruments responded after paving. Planning requirements, problems encountered and costs of installation are presented. The site will use piezoelectric cables in a weigh-in-motion arrangement to trigger the data collection, a microcomputer controlled data acquisition system to analyze multiple sensors simultaneously, and telemetry to monitor the site remotely. Details provide the first time user of instrumentation with valuable information on the planning, problems, costs and coordination required to establish and operate such a site.

A Computer Based Information System for County Equipment Cost Records, Final Report, HR-173, 1975

This appendix is divided into three sections. The first section contains abstracts of each of the eight computer programs in the system, instructions for keypunching the three input documents, and computer operating instructions pertaining to each program. The second section contains system flowcharts for the entire system as well as program flowcharts for each program. The last section contains PL/l program listings of each program.

Bonded, Thin-Lift, Non-Reinforced Portland Cement Concrete Resurfacing, HR-191, 1980

A Research Project involving two, three, four and five inches of bonded Portland Cement Concrete Overlay on a 1.3 mile Portland Cement Concrete pavement was conducted in Clayton County, Iowa, during September, 1977, centering on the following objectives: 1. Determine the mixing and proportioning procedures required in using a conventional, central mix proportioning plant to produce a dense Portland Cement Concrete mixture using standard mixes with super-water reducing admixtures; 2. Determine the economics, longevity and maintenance performance of a bonded, thin-lift, non-reinforced Portland Cement Concrete resurfacing course using conventional procedures, equipment and concrete paving mixtures both with and without super-water reducing admixtures; 3. Determine if an adequate bond between the existing pavement and an overlay of thin-lift, dense, non-reinforced Portland Cement Concrete can be obtained with only special surface cleaning and no surface removal or grinding.

Evaluation of Control Structures for Stabilizing Degrading Stream Channels in Western Iowa, Phases II and III, HR-208A, 1985

Since the turn of the century, tributaries to the Missouri River in western Iowa have entrenched their channels to as much as six times their original depth. This channel degradation is accompanied by widening as the channel side slopes become unstable and landslides occur. The deepening and widening of these streams have endangered about 25% of the highway bridges in 13 counties [Lohnes et al. 1980]. Grade stabilization structures have been recommended as the most effective remedial measure for stream degradation [Brice et al., 1978]. In western Iowa, within the last seven years, reinforced concrete grade stabilization structures have cost between $300,000 and $1,200,000. Recognizing that the high cost of these structures may be prohibitive in many situations, the Iowa Department of Transportation (Iowa DOT) sponsored a study at Iowa State University (ISU) to find low-cost alternative structures. This was Phase I of the stream degradation study. Analytical and laboratory work led to the conclusion that alternative construction materials such as gabions and soil-cement might result in more economical structures [Lohnes et al. 1980]. The ISU study also recommended that six experimental structures be built and their performance evaluated. Phase II involved the design of the demonstration structures, and Phase III included monitoring and evaluating their performance.