RFID Tags for Detecting Concrete Degradation in Bridge Decks, RB08-011, 2013

Steel reinforcing bar (rebar) corrosion due to chlorine ingress is the primary degradation mechanism for bridge decks. In areas where rock salt is used as a de-icing agent, salt water seeps into the concrete through cracks, causing corrosion of the rebar and potentially leading to catastrophic failure if not repaired. This project explores the use of radio frequency identification (RFID) tags as low-cost corrosion sensors. RFID tags, when embedded in concrete, will fail due to corrosion in the same manner as rebar after prolonged exposure to salt water. In addition, the presence of salt water interferes with the ability to detect the tags, providing a secondary mechanism by which this method can work. During this project, a fieldable RFID equipment setup was constructed and tested. In addition to a number of laboratory experiments to validate the underlying principles, RFID tags were embedded and tested in several actual bridge decks. Two major challenges were addressed in this project: issues associated with tags not functioning due to being in close proximity to rebar and issues associated with portland concrete coming in direct contact with the tags causing a detuning effect and preventing the tags from operating properly. Both issues were investigated thoroughly. The first issue was determined to be a problem only if the tags are placed in close proximity to rebar. The second issue was resolved by encapsulating the tag. Two materials, polyurethane spray foam and extruded polystyrene, were identified as providing good performance after testing, both in the lab and in the field.

Methods for Removing Concrete Decks from Bridge Girders, TR-647, 2014

With ever tightening budgets and limitations of demolition equipment, states are looking for cost-effective, reliable, and sustainable methods for removing concrete decks from bridges. The goal of this research was to explore such methods. The research team conducted qualitative studies through a literature review, interviews, surveys, and workshops and performed small-scale trials and push-out tests (shear strength evaluations). Interviews with bridge owners and contractors indicated that concrete deck replacement was more economical than replacing an entire superstructure under the assumption that the salvaged superstructure has adequate remaining service life and capacity. Surveys and workshops provided insight into advantages and disadvantages of deck removal methods, information that was used to guide testing. Small-scale trials explored three promising deck removal methods: hydrodemolition, chemical splitting, and peeling

Pilot Project for a Hybrid Road-Flooding Forecasting System on Squaw Creek, TR-642

A network of 25 sonic stage sensors were deployed in the Squaw Creek basin upstream from Ames Iowa to determine if the state-of-the-art distributed hydrological model CUENCAS can produce reliable information for all road crossings including those that cross small creeks draining basins as small as 1 sq. mile. A hydraulic model was implemented for the major tributaries of the Squaw Creek where IFC sonic instruments were deployed and it was coupled to CUENCAS to validate the predictions made at small tributaries in the basin. This study demonstrates that the predictions made by the hydrological model at internal locations in the basins are as accurate as the predictions made at the outlet of the basin. Final rating curves based on surveyed cross sections were developed for the 22 IFC-bridge sites that are currently operating, and routine forecast is provided at those locations (see IFIS). Rating curves were developed for 60 additional bridge locations in the basin, however, we do not use those rating curves for routine forecast because the lack of accuracy of LiDAR derived cross sections is not optimal. The results of our work form the basis for two papers that have been submitted for publication to the Journal of Hydrological Engineering. Peer review of our work will gives a strong footing to our ability to expand our results from the pilot Squaw Creek basin to all basins in Iowa.

Galvanized Bridge Deck Reinforcing, HR-504, 1992

The deterioration of bridge decks due to steel corrosion is a problem encountered several years ago. This project, using galvanized reinforcement, began over twenty years ago. Since that time, epoxy coated reinforcement has become the specified material used in bridge decks. The decks researched in this project are located on 1-35 in Story County. They were constructed in 1967. The results from the testing done on this project show that galvanizing protects steel from corrosion due to deicing salts, resulting in less/no concrete deterioration.

Pilot Construction Project for Granular Shoulder Stabilization, TR-634, 2013

Granular shoulders need to be maintained on a regular basis because edge ruts and potholes develop, posing a safety hazard to motorists. The successful mitigation of edge-rut issues for granular shoulders would increase safety and reduce the number of procedures currently required to maintain granular shoulders in Iowa. In addition, better performance of granular shoulders reduces the urgency to pave granular shoulders. Delaying or permanently avoiding paving shoulders where possible allows more flexibility in making investments in the road network. To stabilize shoulders and reduce the number of maintenance cycles necessary per season, one possible stabilizing agent—acidulated soybean oil soapstock—was investigated in this research. A pilot testing project was conducted for selected problematic shoulders in northern and northeastern Iowa. Soapstock was applied on granular shoulders and monitored during application and pre- and post-application. Application techniques were documented and the percentage of application success was calculated for each treated shoulder section. As a result of this research, it was concluded that soybean oil soapstock can be an effective stabilizer for granular shoulders under certain conditions. The researchers also developed draft specifications that could possibly be used to engage a contractor to perform the work using a maintenance-type construction contract. The documented application techniques from this project could be used as guidance for those who want to apply soapstock for stabilizing granular shoulders but might not be familiar with this technique.

Iowa Interstate Corridor Plan, 2013

The purpose of this Interstate Corridor Plan (plan) is to provide the Iowa Department of Transportation (Iowa DOT) with an initial screening and prioritization of interstate corridors/segments. This process evaluates the entire interstate system, independent of current financial constraints, using a select group of criteria weighted in terms of their relative significance. The resulting segments would then represent those areas that should be considered for further study (e.g., environmental, design, engineering), with the possibility of being considered for programming by the Iowa Transportation Commission. There was a dominant theme present in conversations with those department stakeholders who have a keen interest in the product of this planning effort. A statement that was often heard was that staff needed more information to help answer the question, “Where do we need to be looking to next, and when?” There was a strong desire to be able to use this plan to help populate that initial pool of candidate segments that would progress towards further study, as discussed below. It was this theme that framed the need for this plan and ultimately guided its development. Further study: As acknowledged at the beginning of this section, the product of this planning effort will be an initial screening and prioritization of interstate corridors/segments. While this initial screening will assist the Iowa DOT in identifying those areas that should be considered for further study, the plan will not identify specific projects or alternatives that could be directly considered as part of the programming process. Bridging the gap between this plan and the programming process are a variety of environmental, design, and engineering activities conducted by various Iowa DOT offices. It is these activities that will further refine the priority corridors/segments identified in this plan into candidate projects. In addition, should the evaluation process developed through this planning effort prove to be successful, it is possible that there will be additional applications, such as future primary system highway plans and statewide freight plans.

Pavement Management Performance Modeling: Evaluating the Existing PCI Equations, RB14-013 2014

The work described in this report documents the activities performed for the evaluation, development, and enhancement of the Iowa Department of Transportation (DOT) pavement condition information as part of their pavement management system operation. The study covers all of the Iowa DOT’s interstate and primary National Highway System (NHS) and non-NHS system. A new pavement condition rating system that provides a consistent, unified approach in rating pavements in Iowa is being proposed. The proposed 100-scale system is based on five individual indices derived from specific distress data and pavement properties, and an overall pavement condition index, PCI-2, that combines individual indices using weighting factors. The different indices cover cracking, ride, rutting, faulting, and friction. The Cracking Index is formed by combining cracking data (transverse, longitudinal, wheel-path, and alligator cracking indices). Ride, rutting, and faulting indices utilize the International Roughness Index (IRI), rut depth, and fault height, respectively.

Transportation in Iowa: A Historical Summary, 1988

“This book traces the development of transportation in Iowa from territorial days to the 19 80s. It shows the evolution of the transportation systems; how they originated, progressed and functioned; their structural organizations; effectiveness in overcoming obstacles, under the guidance of state and federal legislation; and their impact upon the development of the state.” – From the Prologue, page xiii

Making a Modern Highway: Transformation of Iowa Roadways in the Mid-Twentieth Century, 2014

The booklet tells the history of the construction of the Iowa Highway 376 Bridge within the context of significant modernization and expansion of the highway system in Iowa in the 1950s. Curvy, narrow highways were widened and straightened and narrow iron truss bridges were replaced with more modern concrete and steel structures, changing the landscape of rural Iowa. Bridge engineer Herbert A Arthur, who designed the Iowa Highway 376 Bridge, was a prolific bridge engineer in the 1950s. This booklet serves to inform the public of this significant aspect of Iowa transportation history.

Assessment of Asphalt Interlayer Designed on Jointed Concrete, InTrans Project 13-475, 2014

Reflective cracking in hot mix asphalt (HMA) overlays has been a common cause of poor pavement performance in Iowa for many years. Reflective cracks commonly occur in HMA overlays when deteriorated portland cement concrete is paved over with HMA. This results in HMA pavement surfaces with poor ride quality and increased transportation maintenance costs. To delay the formation of cracks in HMA overlays, the Iowa Department of Transportation (Iowa DOT) has begun to implement a crack-relief interlayer mix design specification. The crack-relief interlayer is an asphalt-rich, highly flexible HMA that can resist cracking in high strain loading conditions. In this project, the field performance of an HMA overlay using a one inch interlayer was compared to a conventional HMA overlay without an interlayer. Both test sections were constructed on US 169 in Adel, Iowa as part of an Iowa DOT overlay project. The laboratory performance of the interlayer mix design was assessed for resistance to cracking from repeated strains by using the four-point bending beam apparatus. An HMA using a highly polymer modified binder was designed and shown to meet the laboratory performance test criteria. The field performance of the overlay with the interlayer exceeded the performance of the conventional overlay that did not have the interlayer. After one winter season, 29 percent less reflective cracking was measured in the pavement section with the interlayer than the pavement section without the interlayer. The level of cracking severity was also reduced by using the interlayer in the overlay.

Iowa Field Conference on "D"-Cracking: Nov. 20 & 21, 1967

During the summer of 1963 the Materials Department noted the three to four ·year old concrete pavement on I-80 in Cass County was showing extensive surface cracking adjacent to joints and cracks. An examination of the pavement and a few cores from the cracked areas was made by the I.S.H.C. Materials Department and later by David Stark of the P.C.A. Additional surveys were conducted on other concrete pavement made with coarse aggregate from similar rock from two different sources. Blue-line cracking was found on some primary pavement and the indications of incipient cracks were seen on I-29 in Pottawattamie County, north of Council Bluffs. A good "D"-crack pattern is now evident. Surveys were then made of the entire Interstate concrete pavement. No other sections of Interstate were "D"-cracking, although some sections showed joint discoloration. None of these pavements, including the discolored sections, contained "D"-crack associated aggregates. At the same time as the Interstate survey additional pavements and sources were checked. Some "D"-cracking was noticed on certain sections of primary pavement 5-10 years old, in the vicinity of Waterloo and Cedar Rapids. The "D"-cracked pavement was from three aggregate sources, the Newton, Otis, and Burton Ave. quarries. Other pavements in this area that were older or from· different· coarse aggregate sources were not "D"-cracked. We believe that all the "D"-cracking is related, although dedolomitization is probably involved in the intermediate dolomite rocks.

Assessment of Nondestructive Testing Technologies for Quality Control/Quality Assurance of Asphalt Mixtures, TR-653, 2015

Asphalt pavements suffer various failures due to insufficient quality within their design lives. The American Association of State Highway and Transportation Officials (AASHTO) Mechanistic-Empirical Pavement Design Guide (MEPDG) has been proposed to improve pavement quality through quantitative performance prediction. Evaluation of the actual performance (quality) of pavements requires in situ nondestructive testing (NDT) techniques that can accurately measure the most critical, objective, and sensitive properties of pavement systems. The purpose of this study is to assess existing as well as promising new NDT technologies for quality control/quality assurance (QC/QA) of asphalt mixtures. Specifically, this study examined field measurements of density via the PaveTracker electromagnetic gage, shear-wave velocity via surface-wave testing methods, and dynamic stiffness via the Humboldt GeoGauge for five representative paving projects covering a range of mixes and traffic loads. The in situ tests were compared against laboratory measurements of core density and dynamic modulus. The in situ PaveTracker density had a low correlation with laboratory density and was not sensitive to variations in temperature or asphalt mix type. The in situ shear-wave velocity measured by surface-wave methods was most sensitive to variations in temperature and asphalt mix type. The in situ density and in situ shear-wave velocity were combined to calculate an in situ dynamic modulus, which is a performance-based quality measurement. The in situ GeoGauge stiffness measured on hot asphalt mixtures several hours after paving had a high correlation with the in situ dynamic modulus and the laboratory density, whereas the stiffness measurement of asphalt mixtures cooled with dry ice or at ambient temperature one or more days after paving had a very low correlation with the other measurements. To transform the in situ moduli from surface-wave testing into quantitative quality measurements, a QC/QA procedure was developed to first correct the in situ moduli measured at different field temperatures to the moduli at a common reference temperature based on master curves from laboratory dynamic modulus tests. The corrected in situ moduli can then be compared against the design moduli for an assessment of the actual pavement performance. A preliminary study of microelectromechanical systems- (MEMS)-based sensors for QC/QA and health monitoring of asphalt pavements was also performed.

Best Practices for Low-Cost Safety Improvements on Iowa’s Local Roads, 2008

Many good maintenance practices are done routinely to ensure safe travel on low-volume local roads. In addition, there are many specific treatments that may go beyond the point of routine maintenance and in fact provide additional safety benefits with a relatively low price tag. The purpose of this publication is to try to assemble many of these treatments that are currently practiced in Iowa by local agencies into one, easy-to-reference handbook that not only provides some clarity to each treatment with photos and narrative, but also features references to agencies currently using that technique. Some strategies that are utilized by Iowa, other states, and are topics of research have also been included to allow the user more information about possible options. Even though some areas overlap, the strategies presented have been grouped together in the following areas: Signing and Delineation, Traffic "Calming," Pavement Marking and Rumble Strips/Stripes, Roadside and Clear Zone, Guardrail and Barriers, Lighting, Pavements and Shoulders, Intersections, Railroad Crossings, Bridges and Culverts, and Miscellaneous. The intention is to make this a “living” document, which will continue to be updated and expanded periodically as other existing practices are recognized or new practices come into being.

Evaluating Roadway Subsurface Drainage Practices - Phase II, TR-662, 2015

Well-performing subsurface drainage systems form an important aspect of pavement design by the Iowa Department of Transportation (DOT). The recently completed Iowa Highway Research Board (IHRB) project TR-643 provided extensive insights into Iowa subsurface drainage practices and pavement subdrain outlet performance. However, the project TR-643 (Phase I) forensic testing and evaluation were carried out in a drought year and during the fall season in 2012. Based on the findings of IHRB Project TR-643, the Iowa DOT requested an expanded Phase II study to address several additional research needs: evaluate the seasonal variation effects (dry fall 2012 versus wet spring/summer 2013, etc.) on subdrain outlet condition and performance; investigate the characteristics of tufa formation in Iowa subdrain outlets; investigate the condition of composite pavement subdrain outlets; examine the effect of resurfacing/widening/rehabilitation on subdrain outlets (e.g., the effects of patching on subdrain outlet performance); and identify a suitable drain outlet protection mechanism (like a headwall) and design for Iowa subdrain outlets based on a review of practices adopted by nearby states. A detailed forensic test plan was developed and executed for inspecting the Iowa pavement subdrains in pursuit of fulfilling the Phase II study objectives. The observed outlets with blockage and the associated surface distresses in newly constructed jointed plain concrete pavements (JPCPs) were slightly higher during summer 2013 compared to fall 2012. However, these differences are not significant. Less tufa formation due to the recycled portland cement concrete (RPCC) base was observed with (a) the use of plastic outlet pipe without the gate screen–type rodent guard and (b) the use of blended RPCC and virgin aggregate materials. In hot-mix asphalt (HMA) over JPCP, moisture-related distress types (e.g., reflection cracking) were observed more near blocked drainage outlet locations than near “no blockage” outlet locations. This finding indicates that compromised drainage outlet performance could accelerate the development of moisture-related distresses in Iowa composite pavement systems. ****** Note: This report follows on work report in "Evaluating Roadway Subsurface Drainage Practices, 2013" http://publications.iowa.gov/14902/ Note: This record contains links to the 210 page full report as well as the 3 page tech transfer summary. The summary is NOT deposited separately.

Determination of Flood Dischard Characteristics of Small Drainage Areas, HR-3, Progress Report, 1960

Project HR-3 of the Iowa Highway Research Board has been active since October 1, 1950. The project objective is the determination of flood discharge characteristics of small drainage areas. Funds for the project amount to $10,000 per year of which, by cooperative agreement, the Highway Commission and the U. S. Geological Survey each furnish $5,000. Previous reports have explained the set-up of the project and these explanations will not be repeated in this report.