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Project Details
STATUS

In-Progress

PROJECT NUMBER

22-789, TR-803

START DATE

01/01/22

END DATE

12/31/24

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC, CTRE
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

Researchers
Principal Investigator
Sri Sritharan

Faculty Affiliate

About the research

Prolonged road/lane closures associated with the rehabilitation or replacement of bridges lead to congested traffic conditions, which, among other consequences, pose an increased risk of safety for both construction workers and the traveling public. In an attempt to minimize these concerns, sophisticated procedures, combining the use of prefabricated bridge components, high performance characteristics of unconventional construction materials, and careful planning, are being developed to expedite bridge projects from conception to delivery. These novel techniques can drastically reduce abridge on-site construction time while enhancing both the quality and durability of the completed structure, and have promoted accelerated bridge construction (ABC) among the bridge design community.

Effective ABC methods require easy-to-fabricate and lightweight modules that can be transported to the site and assembled relatively quickly with commonly used equipment. Moreover, the connections of the system must be properly designed and detailed to facilitate assembly and enable the overall structure to achieve a performance that is comparable, if not superior, to that of a similarly cast-in-place (CIP) system. The Iowa DOT has invested in the development of abutment connection details to facilitate implementation of ABC techniques in its practice.

Building on previous research, this project will advance the accelerated bridge construction method for integral bridge abutments supported on steel piles and constructed using prefabricated and in-situ concrete along with other advanced construction techniques (3D printing) and materials as appropriate.

Project Details
STATUS

In-Progress

PROJECT NUMBER

22-788, TR-802

START DATE

03/01/22

END DATE

02/29/24

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

Researchers
Principal Investigator
Behrouz Shafei

Structural Engineer, BEC

Co-Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

About the research

Prestressed concrete structures have become a popular choice for transportation infrastructure applications. According to the National Bridge Inventory, the percentage of bridges built with prestressed concrete technology has been rapidly increased from 15.0% to 23.5% over the past two decades. Specifically, precast prestressed concrete beams (PPCBs) are extensively used for bridge superstructures, owing to a number of favorable attributes, including great quality control on material and workmanship from one side, and fast, economic, and energy-efficient construction from the other side. The bridge superstructures are, however, known to be vulnerable to continuous deterioration. As a consequence, a problem commonly observed in the PPCB that supports the bridge superstructure is that the beam ends experience a faster (and more severe) deterioration compared to the rest of the beam. This is not surprising considering the fact that the beam end regions are subjected to a harsher exposure condition. To minimize serviceability issues and avoid catastrophic failures, effective maintenance and repair efforts are essential. The ultimate goal of this research project is, therefore, to develop feasible and cost-effective preservation strategies to extend the service life of the PPCB used in bridges in service.

Project Details
STATUS

In-Progress

PROJECT NUMBER

21-785, TR-801

START DATE

11/15/21

END DATE

11/30/23

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC, CTRE
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

Researchers
Principal Investigator
Sri Sritharan

Faculty Affiliate

Co-Principal Investigator
Jeramy Ashlock

Faculty Affiliate

About the research

Building on previous research, the proposed project will advance the accelerated bridge construction method for bridge substructures using steel piles and precast pile caps and columns. The weight of the precast members will be reduced using hollow sections, which in turn will improve both construction tolerances and constructability. The hollow sections will be filled with in-situ concrete. The piles will be designed with temporary collars, which will eliminate the need to wait for the concrete to cure before continuing with the superstructure construction.

The research will include a large-scale test unit that will incorporate both vertical and battered steel piles. The testing of the system will incorporate service level and extreme loads and ensure dependable performance of the new system and its components. As part of the testing program, the performance of the column and pile foundations will be examined systematically. Analytical models will be developed to realize the observed performance of the test unit and the components. Using previously discovered analytical and experimental observations and findings, appropriate design recommendations will be developed for improving bridge construction.

Project Details
STATUS

In-Progress

PROJECT NUMBER

21-783, TR-800

START DATE

11/01/21

END DATE

10/31/22

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

Researchers
Principal Investigator
Justin Dahlberg

Acting Director, NCWTS

Co-Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

About the research

Recent advancement in bridge construction technologies, especially with respect to bridge decks and superstructures, have become commonplace in new bridge projects. Substructure construction has not made the same advancements, however. There are existing technologies that have potential for simplifying and expediting the construction of bridge substructures at the same or reduced cost using equipment that is more readily available. In this project, helical pile foundation implementation for bridges will be investigated and a design guide will be produced. This tool will give engineers direction for alternative deep foundation options on bridge structures. This is an advantage for any bridge project, but particularly for low-volume roads where budgetary considerations tend to be of specific priority.

Project Details
STATUS

In-Progress

PROJECT NUMBER

21-781, TR-798, SPR-RE22(009)-8H-00

START DATE

11/01/21

END DATE

04/30/24

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

Researchers
Principal Investigator
Justin Dahlberg

Acting Director, NCWTS

Co-Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

About the research

Recent legislation in the State of Iowa has increased the allowable axle weight of certain implements of husbandry to 25 kips. This change poses a particular concern to those who oversee and manage the construction and preservation of bridge structures. Based upon initial estimates, it is expected that the resulting structural response of bridges will exceed that which would be otherwise seen from current legal loads. This project aims to identify the load response of Iowa bridges to the increased live load limit and develop recommendations for load factors, live load distribution factors, and impact factors for Iowa bridges. Additionally, an Iowa-specific notional vehicle to be used for load rating bridges for recently legislated 25 kip axle vehicles will be developed and proposed.

Project Details
STATUS

Completed

PROJECT NUMBER

18-656, TR-747

START DATE

04/01/18

END DATE

11/19/21

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, PROSPER
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

Researchers
Principal Investigator
Jeramy Ashlock

Faculty Affiliate

Co-Principal Investigator
Halil Ceylan

Director, PROSPER

Co-Principal Investigator
Cassandra J. Rutherford

Iowa State University

Co-Principal Investigator
Bora Cetin

About the research

The goal of this project was to investigate the performance of granular road sections stabilized with quarry fines byproducts and perform a benefit-cost analysis (BCA) to find the most beneficial quarry fines options for stabilization.

Five sources of quarry fines were selected among 19 quarries across Iowa to build 3 test sections in Jones County, Iowa, and 4 sections in Boone County, Iowa. These two sites are among the most populated roads with relatively stiff subbase and subgrade layers, and they suffer from heavy traffic loads and freeze-thaw effects during winter and spring seasons. Construction and maintenance procedures for the test sections are detailed, and the associated costs of aggregate, hauling, and equipment are also documented in this report.

Extensive laboratory and field tests were performed before and after construction, as well as after one seasonal freeze-thaw period from 2019 to 2020, to evaluate and monitor the performance of the constructed sections. A BCA was performed using the documented construction and maintenance costs for service life scenarios of 20, 30, 40, and 50 years. A benefit-cost ratio (BCR) was calculated for each test section for different scenarios based on various performance measures including gravel content change, average fines content, total breakage, gravel-to-sand ratio, stiffness, shear strength, surface roughness, and dust emission. Performance measures were categorized into three overall mechanistic performance-based groups, and their BCRs were compared.

Overall, the results of this study showed that stabilization by quarry fines improved performance by providing binding between the surface aggregates, reducing dust emission and gravel loss, and increasing the stiffness and strength of the surface layers. Stabilization could be cost-effective by reducing the maintenance frequency depending on the material, hauling, and labor costs. The Limestone and Moscow Mine sections in Jones County, and Moscow and Ames Mine sections in Boone County had the best performance and cost-effectiveness among all stabilized sections. Although the Clay Slurry material was helpful to reduce dust emission compared to the rest of the sections, sections with the Clay Slurry were among the average-performance sections, and the increased construction costs made them a less cost-effective option for both counties.

Project Details
STATUS

Completed

PROJECT NUMBER

17-610, TR-724

START DATE

04/15/17

END DATE

10/31/21

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CTRE, 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
Peter Taylor

Director, CP Tech Center

Co-Principal Investigator
Mani Mina

Iowa State University

About the research

Many transportation agencies allocate significant time and resources each year to remove ice and snow from their paved surfaces to achieve a safe, accessible, and operational transportation network. An electrically conductive concrete (ECON) heated pavement system (HPS) has been shown to be a promising alternative to conventional snow removal operations using snowplows and deicing chemicals, which is time-consuming, labor-intensive, and environmentally unfriendly.

An ECON HPS utilizes the inherent electrical resistance of concrete to maintain the pavement surface at above-freezing temperatures and thus prevent snow and ice accumulation on the surface. Such a sustainable concrete pavement system improves its infrastructure resiliency by allowing it to be safe, open, and accessible during even harsh winter storms.

The purpose of this study was to demonstrate the full-scale implementation of 10 ECON HPS slabs at the Iowa Department of Transportation headquarters’ south parking lot in Ames, Iowa. This study consisted of system design and control, field implementation, and sensor instrumentation procedures for the construction of the ECON HPS, which took place during October 2018. A programmable logic controller (PLC) was designed, programmed, and utilized to remotely control, operate, and monitor the system, and the heating performance of the remotely operated ECON slabs was evaluated during the 2018 to 2021 winter seasons using the instrumented sensors under the snow and ice. The performance evaluation showed promising results in achieving snow- and ice-free pavement surfaces through several winter weather events.

Project Details
STATUS

In-Progress

PROJECT NUMBER

21-763, TR-796

START DATE

08/01/21

END DATE

07/31/24

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

About the research

Over 71,000 miles (i.e., over 75%) of county roads in Iowa are granular (unpaved) roads. Iowa granular roads carry low daily traffic volumes (i.e., 10 to 200 vehicles/trucks per day) yet frequently support heavy vehicle (e.g., farm equipment) movements. According to a recent estimate, Iowa’s county road departments spend over $145 million annually on maintenance costs, which predominantly includes over $35 million for blading and over $110 million for resurfacing. In addition, a wide range in granular material quality, supply, and price available in different regions of the state results in significant differences in the level-of-service. Therefore, Iowa county engineers have a specific set of criteria based on their own experiences when designing and managing granular roads. Considering the lack of granular road structural design standards to meet Iowa county engineers’ requirements for current granular road management practices, significant research is needed to develop a comprehensive but practical structural design tool for cost-effective design and construction of local granular road systems in Iowa.

The primary objective of this study is to meet such research needs. This will be achieved through the execution of five concurrent research studies: (1) surveys/interviews, forensic investigations, and laboratory tests to identify the best practices for Iowa granular roads around the state; (2) construction, instrumentation, and performance monitoring of field demonstration sites; (3) development of deterioration prediction models subjected to Iowa granular roadways; (4) cost-effectiveness analysis; and (5) development of a structural design tool and additional guidance documents. The outcomes of this research will substantially improve overall performance, save on maintenance and operation costs, and enhance the safety and mobility of Iowa granular roads by addressing key performance indicators (e.g., drainage, cross-slope, aggregate loss, and freeze/thaw susceptibility) through the granular road design procedure.

Project Details
STATUS

Completed

PROJECT NUMBER

18-640, TR-740

START DATE

01/01/18

END DATE

06/30/21

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
Danny Waid

Iowa County Engineers Service Bureau

Co-Principal Investigator
Brian Moore

Iowa County Engineers Service Bureau

About the research

Recent federal legislation requires state highway agencies (SHA) and local road agencies to utilize performance-based approaches in their pavement management decision-making processes. The use of a remaining service life (RSL) model would be one such performance-based approach that could facilitate the pavement management decision-making process.

This study developed a Microsoft Excel macro and Visual Basic for Applications (VBA)-based Iowa Pavement Analysis Techniques (IPAT) automation tool that Iowa county engineers can use to estimate the project- and network-level pavement performance and RSL. To address this aim, statistics and artificial neural network (ANN)-based pavement performance and RSL models were developed using pavement structural features, traffic, construction history, and pavement performance records obtained from the Iowa Department of Transportation (DOT) Pavement Management Information System (PMIS) and the Iowa county agencies’ database. The accuracy of models was evaluated using real database representing Iowa county pavement systems.

The IPAT tool provides a series of options for four pavement types representing Iowa county pavement systems—jointed plain concrete pavement (JPCP), asphalt concrete (AC) pavement, AC over JPCP, and portland cement concrete (PCC) overlay—to estimate RSL through different approaches based on various conditions and distress data availability from an individual county. As part of data processing, the concept of developing an Iowa historical performance databank (HPD) was introduced and demonstrated by using raw data collected from county pavements. In addition, the feasibility of integrating preservation and rehabilitation techniques for RSL predictions using ANN models was investigated to evaluate the effects of treatments on RSL of pavements.

The IPAT tool is expected to be used as part of performance-based pavement management strategies and to significantly help decision-makers facilitating maintenance and rehabilitation decisions for better prioritization and allocation of resources.

Project Details
STATUS

Completed

PROJECT NUMBER

18-655, TR-746

START DATE

03/22/18

END DATE

04/30/21

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CP Tech Center, PROSPER
SPONSORS

Iowa Department of Transportation
Iowa Highway Research Board

Researchers
Principal Investigator
Peter Taylor

Director, CP Tech Center

Co-Principal Investigator
Halil Ceylan

Director, PROSPER

About the research

The aim of the work described in this report was to investigate the impacts of internally cured (IC) concrete paving on warping in test pavements built in Iowa. The study involved both laboratory investigations and field implementation of internally cured concrete for Iowa pavement systems.

The primary objective of this research was to perform a full-scale field demonstration using IC technology and to investigate its performance in rural roadways. Two overlay construction projects were identified for the field demonstration. Samples of the mixtures were taken at the time of placement and sent to the laboratory for parallel testing with laboratory prepared mixtures.

A number of sensors were embedded in the concrete slabs to monitor moisture and temperature over time. Periodic measurements were taken throughout the year to observe and evaluate the dimensional stability of the slabs.

To assess the value proposition of using internal curing in concrete overlays, life-cycle cost analyses were conducted using reported costs from the projects. Because little structural benefit is expected from the IC mixtures, the assessment was based on a predicted reduction in maintenance costs of the sections due to improved permeability determined in the laboratory tests. Both the net present value (NPV) and equivalent annual annuity (EAA) calculation results indicate a net savings over time with the use of IC technology.

Based on the field and laboratory results, using lightweight fine aggregate (LWFA) improved the concrete hydration for about one month after placing. The biggest challenge appears to be related to obtaining and preconditioning the LWFA.

In summary, the technique does appear to be of benefit for reducing the potential for early-age cracking, improving ride and increasing the longevity of relatively thin overlays. Assuming that the challenges of transportation and storage can be overcome, this is a viable technique to help improve the performance of such pavements.

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