Informed Control Over Inputs and Extent of Industrial Processing, June 2005

Stylized facts regarding the industrial process include emphases on obtaining information about and control over the quality of raw materials. We provide a model that establishes conditions under which informed control involves ensuring uniformity in inputs and increased uniformity encourages more extensive processing. We show when the Boltzmann-Shannon entropy statistic is an appropriate measure of uniformity.

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.

Design Guide and Construction Specifications for National Pollutant Discharge Elimination System (NPDES) Site Runoff Control, 2006

According to the 1972 Clean Water Act, the Environmental Protection Agency (EPA) established a set of regulations for the National Pollutant Discharge Elimination System (NPDES). The purpose of these regulations is to reduce pollution of the nation’s waterways. In addition to other pollutants, the NPDES regulates stormwater discharges associated with industrial activities, municipal storm sewer systems, and construction sites. Phase II of the NPDES stormwater regulations, which went into effect in Iowa in 2003, applies to construction activities that disturb more than one acre of ground. The regulations also require certain communities with Municipal Separate Storm Sewer Systems (MS4) to perform education, inspection, and regulation activities to reduce stormwater pollution within their communities. Iowa does not currently have a resource to provide guidance on the stormwater regulations to contractors, designers, engineers, and municipal staff. The Statewide Urban Design and Specifications (SUDAS) manuals are widely accepted as the statewide standard for public improvements. The SUDAS Design manual currently contains a brief chapter (Chapter 7) on erosion and sediment control; however, it is outdated, and Phase II of the NPDES stormwater regulations is not discussed. In response to the need for guidance, this chapter was completely rewritten. It now escribes the need for erosion and sediment control and explains the NPDES stormwater regulations. It provides information for the development and completion of Stormwater Pollution Prevention Plans (SWPPPs) that comply with the stormwater regulations, as well as the proper design and implementation of 28 different erosion and sediment control practices. In addition to the design chapter, this project also updated a section in the SUDAS Specifications manual (Section 9040), which describes the proper materials and methods of construction for the erosion and sediment control practices.

Integrated Materials and Construction Practice for Concrete Pavement: A State-of-the-Practice Manual, 2006

At the heart of all concrete pavement projects is the concrete itself. This manual is intended as both a training tool and a reference to help concrete paving engineers, quality control personnel, specifiers, contractors, suppliers, technicians, and tradespeople bridge the gap between recent research and practice regarding optimizing the performance of concrete for pavements. Specifically, it will help readers do the following:

Dust Control Using an Asphalt Emulsion, HR-196, 1977

In an effort to control fugitive dust on a gravel surfaced roadway in Boone County, a cationic asphalt emulsion was blended with warm water and applied with an asphalt distributor. The test included various application procedures. After visual observations, it was concluded that this procedure utilizing a dilute asphalt emulsion was not an effective method of dust control.

Control of Concrete Deterioration Due to Trace Compounds in Deicers, Phase II, HR-299, 1989

This report presents results of research on ways to reduce the detrimental effects of sulfate-tainted rock salt deicers on portland cement concrete used for highway pavements. Repetitious experiments on the influence of fly ash on the mortar phase of concrete showed significant improvement in resistance to deicing brines is possible. Fifteen to twenty percent by weight of fly ash replacement for portland cement was found to provide optimum improvement. Fly ashes from five sources were evaluated and all were found to be equally beneficial. Preliminary results indicate the type of coarse aggregate also plays an important role in terms of concrete resistance to freeze-thaw in deicing brines. This was particularly true for a porous ferroan dolomite thought to be capable of reaction with the brine. In this case fly ash improved the concrete, but not enough for satisfactory performance. An intermediate response was with a porous limestone where undesirable results were observed without fly ash and adequate performance was realized when 15% fly ash was added. The best combination for making deicer-resistant concrete was found to be with a non-porous limestone. Performance in brines was found to be adequate without fly ash, but better when fly ash was included. Consideration was given to treating existing hardened concrete made with poor aggregate and no fly ash to extend pavement life in the presence of deicers, particularly at joints. Sodium silicate was found to improve freeze-thaw resistance of mortar and is a good candidate for field usage because of its low cost and ease of handling.

Glasgrid Fabric to Control Reflective Cracking, HR-535, 1990

The major problem with durability of asphalt cement concrete (ACC) overlays to rehabilitate jointed portland cement concrete (PCC) pavement comes from reflective cracking. The objective of this research was to evaluate the effectiveness of Glasgrid in regard to preventing reflection cracking. Glasgrid is a glass fiber mesh with 1/2 inch by 1 inch openings (Figure 1). Each strand is composed of many small glass fibers. After the grid is formed, it is coated with a polymer modified asphalt cement. In 1986, four experimental Glasgrid test sections were incorporated into Polk County project IR-35-2(191)67--12-77 on Interstate 35 from IA 5 to the west 1-80 interchange on the west edge of Des Moines, Single and double layers of Glasgrid were placed over transverse cracks and joints of the existing PCC pavement. The Glasgrid was placed on the PCC pavement for one section and between lifts of the ACC resurfacing on the other three sections. The four Glasgrid sections were compared to two sections without Glasgrid for four years. The sections were reviewed annually to determine how many cracks or joints had reflected through the resurfacing. Glasgrid placed on the PCC pavement was more effective at preventing reflection cracking than Glasgrid between lifts of AC resurfacing. In general, Glasgrid yielded a small reduction or retardation in the amount of reflection cracking, but not sufficient to justify additional expense for the use of Glasgrid.

Evaluation of Photoacoustic Spectroscopy for Quality Control of Cement, TR-409, 1998

This report discusses the feasibility of using infrared photoacoustic spectroscopy (PAS) as a viable technique that can quickly provide information on cement composition prior to use. The PAS technique is of interest because the cost is much lower than for other types of instrumentation used for mineral analysis, it requires virtually no sample preparation, and it can perform multi-component analysis in a matter of minutes. Feasibility of the technique was based on the ability of PAS to identify and quantify sulfate species and major cement matrix components. Strengths and limitations of the technique are presented.

Soil Erosion Control for Secondary Roads, HR-155

Research project HR-155 was initiated to study soil erosion problems along the secondary road system in Iowa and to find a substitute for straw for the control of soil erosion during the period of seed establishment. Accordingly, six field research sites were established to test the ability of commercial soil conditioners to control soil erosion. The six field research sites were selected on the basis of terrain and type of soil material exposed on the cut-slope areas.

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.

Optimization of Snow Drifting Mitigation and Control Methods for Iowa Conditions Part II, TR-626, 2015

Blowing and drifting of snow is a major concern for transportation efficiency and road safety in regions where their development is common. One common way to mitigate snow drift on roadways is to install plastic snow fences. Correct design of snow fences is critical for road safety and maintaining the roads open during winter in the US Midwest and other states affected by large snow events during the winter season and to maintain costs related to accumulation of snow on the roads and repair of roads to minimum levels. Of critical importance for road safety is the protection against snow drifting in regions with narrow rights of way, where standard fences cannot be deployed at the recommended distance from the road. Designing snow fences requires sound engineering judgment and a thorough evaluation of the potential for snow blowing and drifting at the construction site. The evaluation includes site-specific design parameters typically obtained with semi-empirical relations characterizing the local transport conditions. Among the critical parameters involved in fence design and assessment of their post-construction efficiency is the quantification of the snow accumulation at fence sites. The present study proposes a joint experimental and numerical approach to monitor snow deposits around snow fences, quantitatively estimate snow deposits in the field, asses the efficiency and improve the design of snow fences. Snow deposit profiles were mapped using GPS based real-time kinematic surveys (RTK) conducted at the monitored field site during and after snow storms. The monitored site allowed testing different snow fence designs under close to identical conditions over four winter seasons. The study also discusses the detailed monitoring system and analysis of weather forecast and meteorological conditions at the monitored sites. A main goal of the present study was to assess the performance of lightweight plastic snow fences with a lower porosity than the typical 50% porosity used in standard designs of such fences. The field data collected during the first winter was used to identify the best design for snow fences with a porosity of 50%. Flow fields obtained from numerical simulations showed that the fence design that worked the best during the first winter induced the formation of an elongated area of small velocity magnitude close to the ground. This information was used to identify other candidates for optimum design of fences with a lower porosity. Two of the designs with a fence porosity of 30% that were found to perform well based on results of numerical simulations were tested in the field during the second winter along with the best performing design for fences with a porosity of 50%. Field data showed that the length of the snow deposit away from the fence was reduced by about 30% for the two proposed lower-porosity (30%) fence designs compared to the best design identified for fences with a porosity of 50%. Moreover, one of the lower-porosity designs tested in the field showed no significant snow deposition within the bottom gap region beneath the fence. Thus, a major outcome of this study is to recommend using plastic snow fences with a porosity of 30%. It is expected that this lower-porosity design will continue to work well for even more severe snow events or for successive snow events occurring during the same winter. The approach advocated in the present study allowed making general recommendations for optimizing the design of lower-porosity plastic snow fences. This approach can be extended to improve the design of other types of snow fences. Some preliminary work for living snow fences is also discussed. Another major contribution of this study is to propose, develop protocols and test a novel technique based on close range photogrammetry (CRP) to quantify the snow deposits trapped snow fences. As image data can be acquired continuously, the time evolution of the volume of snow retained by a snow fence during a storm or during a whole winter season can, in principle, be obtained. Moreover, CRP is a non-intrusive method that eliminates the need to perform man-made measurements during the storms, which are difficult and sometimes dangerous to perform. Presently, there is lots of empiricism in the design of snow fences due to lack of data on fence storage capacity on how snow deposits change with the fence design and snow storm characteristics and in the estimation of the main parameters used by the state DOTs to design snow fences at a given site. The availability of such information from CRP measurements should provide critical data for the evaluation of the performance of a certain snow fence design that is tested by the IDOT. As part of the present study, the novel CRP method is tested at several sites. The present study also discusses some attempts and preliminary work to determine the snow relocation coefficient which is one of the main variables that has to be estimated by IDOT engineers when using the standard snow fence design software (Snow Drift Profiler, Tabler, 2006). Our analysis showed that standard empirical formulas did not produce reasonable values when applied at the Iowa test sites monitored as part of the present study and that simple methods to estimate this variable are not reliable. The present study makes recommendations for the development of a new methodology based on Large Scale Particle Image Velocimetry that can directly measure the snow drift fluxes and the amount of snow relocated by the fence.

Mission-Oriented Dust Control and Surface Improvement Processes for Unpaved Roads, HR-194, 1981

Six subject areas prompted the broad field of inquiry of this mission-oriented dust control and surface improvement project for unpaved roads: • DUST--Hundreds of thousands of tons of dust are created annually by vehicles on Iowa's 70,000 miles of unpaved roads and streets. Such dust is often regarded as a nuisance by Iowa's highway engineers. • REGULATIONS--Establishment of "fugitive dust" regulations by the Iowa DEQ in 1971 has created debates, conferences, legal opinions, financial responsibilities, and limited compromises regarding "reasonable precaution" and "ordinary travel," both terms being undefined judgment factors. • THE PUBLIC--Increased awareness by the public that regulations regarding dust do in fact exist creates a discord of telephone calls, petitions, and increasing numbers of legal citations. Both engineers and politicians are frustrated into allowing either the courts or regulatory agencies to resolve what is basically a professional engineering responsibility. • COST--Economics seldom appear as a tenet of regulatory strategies, and in the case of "fugitive dust," four-way struggles often occur between the highway professions, political bodies, regulatory agencies, and the general public as to who is responsible, what can be done, how much it will cost, or why it wasn't done yesterday. • CONFUSION--The engineer lacks authority, and guidelines and specifications to design and construct a low-cost surf acing system are nebulous, i.e., construct something between the present crushed stone/gravel surface and a high-type pavement. • SOLUTION--The engineer must demonstrate that dust control and surface improvement may be engineered at a reasonable cost to the public, so that a higher degree of regulatory responsibility can be vested in engineering solutions.

Demonstration and Field Evaluation of Alternative Portland Cement Concrete Pavement Reinforcement Materials, HR-1069, 2003

Transverse joints are placed in portland cement concrete pavements to control the development of random cracking due to stresses induced by moisture and thermal gradients and restrained slab movement. These joints are strengthened through the use of load transfer devices, typically dowel bars, designed to transfer load across the joint from one pavement slab to the next. Epoxy coated steel bars are the materials of choice at the present time, but have experienced some difficulties with resistance to corrosion from deicing salts. The research project investigated the use of alternative materials, dowel size and spacing to determine the benefits and limitations of each material. In this project two types of fiber composite materials, stainless steel solid dowels and epoxy coated dowels were tested for five years in side by side installation in a portion of U.S. 65 near Des Moines, Iowa, between 1997 and 2002. The work was directed at analyzing the load transfer characteristics of 8-in. vs. 12-in. spacing of the dowels and the alternative dowel materials, fiber composite (1.5- and 1.88-in. diameter) and stainless steel (1.5-in. diameter), compared to typical 1.5-in. diameter epoxy-coated steel dowels placed on 12-in. spacing. Data were collected biannually within each series of joints and variables in terms of load transfer in each lane (outer wheel path), visual distress, joint openings, and faulting in each wheel path. After five years of performance the following observations were made from the data collected. Each of the dowel materials is performing equally in terms of load transfer, joint movement and faulting. Stainless steel dowels are providing load transfer performance equal to or greater than epoxy-coated steel dowels at the end of five years. Fiber reinforced polymer (FRP) dowels of the sizes and materials tested should be spaced no greater than 8 in. apart to achieve comparable performance to epoxy coated dowels. No evidence of deterioration due to road salts was identified on any of the products tested. The relatively high cost of stainless steel solid and FRP dowels was a limitation at the time of this study conclusion. Work is continuing with the subject materials in laboratory studies to determine the proper shape, spacing, chemical composition and testing specification to make the FRP and stainless (clad or solid) dowels a viable alternative joint load transfer material for long lasting portland cement concrete pavements.

Evaluation of DuroTrim Vegetation Control Mats, HR-2090, 2002

The routine maintenance along Iowa's highways and roadways during the summer growing season is a time consuming and costly endeavor. Trimming around guardrail posts and delineator posts is especially costly due to the handwork required. Trimming costs account for approximately 50% of the shoulder mowing costs according to expense figures obtained from the Iowa Department of Transportation (DOT), Office of Maintenance. The FY 2001 statewide trimming costs for the Iowa DOT was approximately $430,000 ($305,000 labor, $125,000 equipment and materials). This product would be required to perform well for 9-21 years, on average, in order to recoup the cost of installation. This includes the durability of the product, but not the cost of repair due to traffic damage, snowplow and wing damage, or damage caused by mowing operations. Maintenance costs associated with vegetation creep over the mats and repair costs would extend the required service life. As a result of resource realignment, the Iowa DOT roadside maintenance policy, for FY 2003 and the future, will be to eliminate trimming around delineator posts unless the reflector is obstructed. This policy change will effectively eliminate the need for weed control mats due to the significant reduction in trimming. The use of the weed control mats could be justified in areas that are dangerous to maintenance workers such as guardrail installations in high traffic areas. Because the delineator posts are further from the edge of the traveled roadway, there is a reduced risk to the maintenance workforce while hand trimming. Because the DuroTrim Vegetation Control Mats appear to have performed adequately in the field trial, they could be considered for use, where safety conditions warrant. That use should be limited, however, due to the considerable initial cost and changes in Iowa DOT roadside maintenance policy. Application should be limited to instances where the use of the DuroTrim Vegetation Control Mats would have a significant impact on the safety of the roadside maintenance workers. The cost savings, due to the elimination of the trimming and mowing alone, is not enough to justify their use in most situations at their current cost. The test sections will continue to be monitored periodically so that approximate service life can be determined.

Evaluation of Deicing Materials and Corrosion Reducing Treatments for Deicing Salts, TR-471, 2007

Effective winter maintenance makes use of freezing-point-depressant chemicals (also known as ice-control products) to prevent the formation of the bond between snow and ice and the highway pavement. In performing such winter maintenance, the selection of appropriate ice-control products for the bond prevention task involves consideration of a number of factors, as indicated in Nixon and Williams (2001). The factors are in essence performance measurements of the ice-control products, and as such can be easily incorporated into a specification document to allow for selection of the best ice-control products for a given agency to use in its winter maintenance activities. Once performance measures for de-icing or anti-icing chemicals have been specified, this allows the creation of a quality control program for the acceptance of those chemicals. This study presents a series of performance measurement tests for ice-control products, and discusses the role that they can play in such a quality control program. Some tests are simple and rapid enough that they can be performed on every load of icecontrol products received, while for others, a sampling technique must be used. An appropriate sampling technique is presented. Further, each test is categorized as to whether it should be applied to every load of ice-control products or on a sampling basis. The study includes a detailed literature review that considers the performance of ice-control products in three areas: temperature related performance, product consistency, and negative side effects. The negative side effects are further broken down into three areas, namely operational side effects (such as chemical slipperiness), environmental side effects, and infrastructural side effects (such as corrosion of vehicles and damage to concrete). The review indicated that in the area of side effects the field performance of ice-control products is currently so difficult to model in the laboratory that no particular specification tests can be recommended at this time. A study of the impact of ice-control products on concrete was performed by Professor Wang of Iowa State University as a sub-contract to this study, and has been presented to the Iowa Highway Research Board prior to this report.