CLOSE OVERLAY
Project Details
STATUS

In-Progress

PROJECT NUMBER

23-859, TR-823

START DATE

07/01/23

END DATE

07/31/25

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CTRE
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

Researchers
Principal Investigator
Jeramy Ashlock

Faculty Affiliate, InTrans

About the research

The project aligns with the Iowa Department of Transportation’s (DOT’s) focus areas of sustainability and technology. Maintenance and rehabilitation of granular-surfaced roads consumes significant portions of counties’ annual budgets, as well as large amounts of natural resources in the form of virgin aggregates. By assessing the performance of different test sections constructed with and without the Perma-Zyme stabilization product through two winter-spring cycles, the Iowa DOT and county engineers will better understand the life-cycle costs and relative advantages of using the enzymatic stabilizer as well as the different construction methods (i.e., compaction by sheepsfoot vs. smooth-drum roller during construction).

Most importantly, the project would establish a new Granular Surfaced Roads Test Facility comprising several miles of granular-surfaced roads at Camp Dodge, through a cooperative relationship with the Iowa Army National Guard. The facility would enable long-term research on unpaved roads with great efficiency by reducing travel time compared to locating test sections in several counties around the state and by enabling many different projects on an ongoing basis in one central location. Overall, the long-term benefits of the project will be to improve the quality, longevity, and state of good repair of Iowa roadways, which constitute a vital component of Iowa’s infrastructure.

 

Project Details
STATUS

In-Progress

PROJECT NUMBER

23-845, TR-822

START DATE

04/15/23

END DATE

04/30/28

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, PROSPER
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

Researchers
Principal Investigator
Halil Ceylan

Director, PROSPER

Co-Principal Investigator
Sunghwan Kim

Associate Director, PROSPER

Co-Principal Investigator
Bo Yang

About the research

In recent years, various proprietary biobased fog sealers or rejuvenators have been introduced and marketed as potentially costeffective and environmentally friendly alternatives to traditional petroleumbased sealers for preserving asphalt roads. The RePLAY Agricultural Oil Seal and Preservation Agent, as one such biobased fog sealer, and its performance, has been evaluated on a 3.3mile pilot testing section located in Clinton County, Iowa, for five consecutive years (i.e., summer 2016 through summer 2021). This study has important insights about RePLAY and its firstlevel field implementation in Iowa. However, further research is needed to identify the frequencies and benefits of the reapplication of RePLAY and further evaluate and validate its cost effectiveness. In addition, Clinton County has interested in evaluating the reapplication of RePLAY at the same project site for extending its use on other project sites. This research will be performed in response to such a research need and interest and will be achieved through the execution of the following primary tasks: (1) developing and executing a detailed field experimental plan, (2) evaluating and validating cost effectiveness, (3) executing subsequent technology transfer and information dissemination activities and developing implementation plans with recommendations, and (4) publishing final research project documents.

This research project will be highly helpful to the Iowa Department of Transportation and Iowa counties in better understanding the benefits of the reapplication of RePLAY while facilitating their decision making in selecting costeffective application frequency options.

Project Details
STATUS

Completed

PROJECT NUMBER

18-659, TR-749

START DATE

05/15/18

END DATE

05/30/23

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CP Tech Center, PROSPER
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

Researchers
Principal Investigator
Halil Ceylan

Director, PROSPER

Co-Principal Investigator
Sunghwan Kim

Associate Director, PROSPER

About the research

Curling and warping behavior due to temperature and moisture variation has been widely considered an influential factor affecting the smoothness of jointed plain concrete pavement (JPCP). In recent decades, while extensive efforts have been made to quantify the impact of curling and warping-related deflections on the smoothness of JPCP, a standardized method for characterizing the effects of environmental factors on JPCP smoothness is still unavailable. A Phase I study examined curling and warping conditions at six sites using a stationary light detection and ranging (LiDAR) system and developed recommendations to minimize curling and warping based on literature review findings. However, the data collection effort in the Phase I study was limited and was insufficient to validate the recommendations derived from the literature review.

The Phase II study described in this report aimed to evaluate and quantify the impact of curling and warping on Iowa concrete pavements and determine the factors that most influence curling and warping behavior. A high-speed profilometer and a LiDAR device were utilized to execute a large-scale field data collection plan for JPCP sites in Iowa, including Long-Term Pavement Performance (LTPP) Program highways, non-LTPP highways, and county roads and city streets. The variables evaluated in this study included temperature and moisture gradients, seasonal and diurnal effects, slab geometry, pavement structural design, mix design, and construction conditions. A validated MATLAB-based algorithm with two different curve-fitting models was coded to evaluate the degrees of curling and warping in multiple ways. This study also used statistical analyses to select the variables that significantly affect curling and warping behavior. The proposed actionable pavement design and construction recommendations will help minimize curling and warping and correct curling and warping-related performance issues.

Project Details
STATUS

Completed

PROJECT NUMBER

18-670, TR-762

START DATE

09/01/18

END DATE

03/31/23

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, PROSPER
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

Researchers
Principal Investigator
Halil Ceylan

Director, PROSPER

Co-Principal Investigator
Sunghwan Kim

Associate Director, PROSPER

Co-Principal Investigator
In-Ho Cho
Co-Principal Investigator
Danny Waid
Co-Principal Investigator
Brian Moore

About the research

Iowa has three classes of public roads: state primary highways, county (secondary) roads, and city streets. Among these, Iowa county roads serve rural Iowa transport needs by assuring a public road connection (i.e., to local access roads) for serving as conduits that channel the flow of people and commodities to and from towns and terminals (i.e., farm-to-market roads). Many Iowa county pavement systems are multilayered structures that have experienced multiple cycles of construction and renewal that make it more complex to estimate pavement structures’ current structural capacities.

This study developed a Microsoft Excel macro and Visual Basic for Applications (VBA)-based automated Pavement Structural Analysis Tool (PSAT) with three analyzing options—asphalt concrete (AC) pavement systems with 1 to 10 layers on a (1) stabilized base, (2) granular base, and (3) stabilized base and granular base—to estimate the current structural capacities of in-service pavement systems by following consecutive sections within the user-friendly platform. To address this aim, a systematic approach to develop a highly realistic annotated synthetic database was created for use in artificial neural network (ANN)-based pavement response prediction models that required inputs of pavement materials and structural features and outputs of pavement responses, deflections, and strains at critical locations within the pavement structure. In addition, the equivalent layer theory (ELT) concept was integrated into the PSAT to simplify multilayered pavement systems into three-layered systems—an asphalt layer, a base layer, and a subgrade layer. Thus, it could make it easier for an Iowa county engineer to understand the current structural capacities of in-service county pavements. Mechanistic- and empirical-based approaches were also integrated into the tool to estimate the remaining service life (RSL) associated with two types of major failures for flexible pavements, namely fatigue and rutting failures, by relating pavement responses predicted by the ANN models through transfer functions. The PSAT is expected to be used as part of routine pavement analysis, design, and asset management practices for better prioritization and allocation of resources, as well as to support effective communication related to pavement needs both with the public and with elected officials.

Project Details
STATUS

In-Progress

PROJECT NUMBER

23-842, TR-820

START DATE

01/01/23

END DATE

06/30/26

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

PARTNERS

Wiss, Janney, Elstner Associates, Inc.

Researchers
Principal Investigator
Justin Dahlberg

Director, BEC

Co-Principal Investigator
Behrouz Shafei

Structural Engineer, BEC

Co-Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

About the research

Bridge decks are often the first bridge component requiring major repair or complete replacement. Since the early 2000s, a new class of cementbased materials, known as ultra-high performance concrete (UHPC), has become available. UHPC is nearly impenetrable and has many other highquality attributes. A bridge will soon be constructed that has a deck comprised of traditional concrete plus a UHPC overlay course. The objective of this study is to monitor and evaluate the construction of the twocourse deck as well as the performance of the deck for 2 years postconstruction. The study will consist of a literature review of twocourse decks and UHPC overlay construction to determine best practices; field monitoring during construction to document construction quality; a laboratory investigation of the twocourse deck system to assess its durability; load tests and field monitoring for 2 years; and service life and lifecycle cost analyses to compare the performance of the twocourse deck system with that of more typical deck systems. The final deliverables will communicate the lessons learned from the project and provide guidance for future design, construction, and QA/QC practices regarding bridge deck construction using a UHPC top course.

Project Details
STATUS

Completed

PROJECT NUMBER

18-647, TR-743

START DATE

02/01/18

END DATE

02/28/23

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

Researchers
Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

About the research

The objective of this project was to demonstrate the field implementation of an innovative longitudinal joint design developed during a previous phase of research. To achieve this objective, a yet-to-be-constructed box girder bridge in Washington County, Iowa, was selected to demonstrate the construction and performance of the joint.

In order to evaluate the joint’s performance, a seven-day period of field monitoring was conducted shortly after construction was completed. In addition, long-term evaluation of the joint was performed through the completion of live load field tests and deck concrete crack inspections. The live load tests were performed every 12 months, and crack inspections of the bridge deck were performed every six months. During the field tests and monitoring, temperature, strain, and displacement data were collected at critical locations and analyzed to evaluate joint performance with respect to cracking resistance and load distribution.

The results indicate that the innovative joint is sufficient to resist early-age longitudinal joint cracking. Joint cracks that were seen on another box girder bridge with traditional narrow joints were not observed in this case. The innovative joint performed well with respect to load distribution. The whole bridge superstructure behaved as an integrated structure regardless of the transverse location of a passing truck. In addition, the box girder bridge was constructed using integral abutments, which added transverse restraint and positively affected the strain distribution at the joint ends.

Project Details
STATUS

Completed

PROJECT NUMBER

18-633, TR-738

START DATE

01/01/18

END DATE

02/28/23

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

Researchers
Principal Investigator
Behrouz Shafei

Structural Engineer, BEC

About the research

Shrinkage and temperature forces are known to have short- and long-term effects on both the superstructures and substructures of bridges. In the substructure, such effects are more pronounced if frame piers are used, given their volumetric change is often restrained.

The main objective of this research was to investigate the forces developed in frame piers and their supporting foundations due to volumetric changes caused by thermal and shrinkage effects. For this purpose, a set of finite element (FE) models capable of simulating shrinkage strain, creep strain, thermal strain, strength development of concrete, and nonlinear behavior of concrete were developed and calibrated using experimental test results. Field data were then collected from bridges instrumented with vibrating wire strain gauges embedded in the frame piers at the time of construction. Further to obtaining firsthand information from the field, the FE models were validated using collected field data. Various frame pier geometries were then analyzed using the validated model to identify the most susceptible geometries.

The results of the study indicated that frame piers cast in Iowa on warm summer days, particularly in June and July, experience the most demand from temperature and shrinkage effects compared to frame piers cast at other times of the year. The most critical factors affecting frame pier susceptibility were found to be column stiffness, length of the cap beam, and flexural stiffness of the cap beam. Column stiffness was observed to be the most impactful factor on the susceptibility of frame piers to these effects. Basic susceptibility metrics, such as the length of the frame and the length-to-height ratio of the frame, were found to be not accurate enough to predict susceptibility, as accurate susceptibility metrics must account for column stiffness and column restraint factors. These results led to the development of two-dimensional linear elastic models that simplified the assessment process without losing accuracy. Overall, the requirements set by the Iowa DOT’s Bridge Design Manual were found to be adequate in capturing the performance of frame piers subjected to temperature and shrinkage forces.

Project Details
STATUS

Completed

PROJECT NUMBER

18-681, TR-764

START DATE

12/15/18

END DATE

02/28/23

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, PROSPER
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board
Recycled Materials Resource Center (RMRC)
University of Wisconsin-Madison

Researchers
Principal Investigator
Halil Ceylan

Director, PROSPER

Co-Principal Investigator
Bora Cetin
Co-Principal Investigator
Michael Perez

About the research

Concrete diamond grinding on pavement projects generates a nonhazardous waste byproduct called concrete grinding residue (CGR). CGR has known cementitious characteristics that suggest a latent use as a soil-stabilizing amendment, especially for poor and problematic soils.

In this study, Western Iowa loess soil was amended with CGR and subjected to rainfall simulations and wind erosion tests to measure the erodibility of several soil mixtures. The results of the rainfall simulations showed that CGR-amended silty soil (loess) had only slightly different optimum moisture contents and maximum dry densities compared to untreated loess, while rainwater runoff samples of CGR-amended loess exhibited dramatically higher turbidity and total suspended solids. The results of the wind erosion tests showed that erosion was lower in more granular shoulder material and higher in shoulder material containing more organics. Wind erosion tests performed on CGR-amended Western Iowa loess showed modest improvement in this highly friable silty soil compared to untreated loess.

A field study conducted in Washington and Clinton Counties in Iowa compared CGR-stabilized and untreated sections to determine the effectiveness of CGR as a stabilizer for shoulder material. The CGR-stabilized sections in Washington County did not show significant improvement in strength, while the CGR-stabilized sections in Clinton County exhibited a 20% to 40% improvement in the composite elastic modulus and California bearing ratio values.

Project Details
STATUS

In-Progress

PROJECT NUMBER

22-829, TR-816

START DATE

11/01/22

END DATE

04/30/25

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CP Tech Center
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

Researchers
Principal Investigator
Peter Taylor

Director, CP Tech Center

Co-Principal Investigator
Dan King

Research Engineer, CP Tech Center

Co-Principal Investigator
Halil Ceylan

Director, PROSPER

About the research

Fiber-reinforced concrete (FRC) has become more widely used in thin concrete overlays in recent years. It is well known that synthetic macro-fibers increase the fracture toughness and residual strength of concrete, which mitigates cracking and improves the fatigue life of concrete overlays. Some of the other benefits of fiber-reinforcement could further benefit the performance and service life of concrete overlays by improving joint behavior, load transfer, and pavement smoothness. However, the performance benefits of these mechanisms are not well-quantified and are not considered in current concrete overlay design procedures. This study will take comprehensive performance measurements at a number of FRC overlay test sections that have been built in Iowa in recent years. The analysis will provide more insight into the full benefits of fiber-reinforcement and how they impact design choices and overlay service life. With a more complete understanding of the performance benefits of using fibers in concrete overlays, agencies would be able to optimize their FRC overlay designs, better predict long-term performance, and use resources more efficiently for maintaining Iowa’s roadway network.

Project Details
STATUS

In-Progress

PROJECT NUMBER

22-818, TR-818

START DATE

10/01/22

END DATE

09/30/24

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, CTRE, Iowa LTAP
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

Researchers
Principal Investigator
Keith Knapp

Director, Iowa LTAP

Co-Principal Investigator
David Veneziano

Safety Circuit Rider, LTAP

About the research

Each year a city public works focus group is convened the day before the spring conference of the Iowa Chapter of the American Public Works Association (APWA). Approximately five years ago, an idea was proposed at this focus group that responded to an identified need for more useful guidance related to the overall and elemental conversion of four-lane undivided roadway to three lanes (i.e., one lane in each direction and a two-way left-turn lane [TWLTL]). A literature review by the Iowa Department of Transportation (DOT) showed that a significant amount of material has been created on this subject. In fact, there has been so much documentation that it can be a challenge to practitioners. It was concluded by the project development team there was a need to combine this information in a more useful manner. The tasks in this project were designed to respond to this continuing need.

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