MPC
Research Projects (2007-08)

Identifying Number

MPC-285

Project Title

Structural Performance of Prestressed Self-Consolidating Concrete Girders Made with Limestone Aggregates, Year 1

University

South Dakota State University

Project Investigators

Dr. Nadim Wehbe and Dr. Arden Sigl

Description of Project Abstract

Recent studies have shown that the use of self-consolidating concrete (SCC) for prestressed bridge girders results in improved finished quality, increased production efficiency, and reduced labor cost (Cameron, 2003). Because of its favorable properties, the Federal Highway Administration and the precast concrete industry have been promoting the research and development of SCC for structural applications in bridges. SCC was first developed in Japan in 1988 to compensate for the lack of skilled labor (Goodier, 2003). The introduction of SCC in Japan was followed by research and development in Europe and, to a lesser extent, in North America. A main issue that needed to be addressed in the early development of SCC was the segregation of coarse aggregates. Nowadays, the concrete industry can produce SCC that is stable and free of aggregate segregation. Studies of concrete cores taken from cured SCC beam and column specimens have shown uniformity in material properties and absence of aggregate segregation (Sonebi et al., 2003; Khayat et al., 2001).

The use of SCC in prestressed applications is relatively new to local designers and producers in South Dakota. Because of the lack of data on the performance of SCC using South Dakota aggregates, there is hesitancy by local engineers and producers to design and fabricate prestressed SCC bridge girders. If properly specified and used, SCC has the potential to yield more economical and higher quality prestressed concrete products. To take advantage of this new technology, there is a need to study production feasibility and structural performance of prestressed SCC bridge girders made with South Dakota aggregates.

Researchers at South Dakota State University (SDSU) are currently conducting an experimental and analytical study on full-scale prestressed SCC bridge girders. The SCC mix used for the girders is made with quartzite aggregates that are commonly used in eastern South Dakota. Funding for the study is provided by the College of Engineering at SDSU and a local producer in Sioux Falls (Gage Bros). In western South Dakota, limestone aggregates are used in the production of concrete. In order to assure the applicability of prestressed concrete statewide, a similar fabrication and testing regimen needs to be conducted on girders made with limestone aggregate. A local producer in Rapid City (Cretex West) has agreed to produce and fund the cost of the needed girders for the study.

Project Objectives

1. Evaluate the feasibility and performance of SCC using limestone coarse aggregate in prestressed concrete products.
2. Develop draft specifications, acceptance criteria, mix qualifications, and guidelines for use of SCC containing either limestone or quartzite in prestressed concrete by SDDOT.

Project Approach/Methods

The project will include the following tasks:

• Task 1 – Review literature regarding SCC practices for prestressed applications in other state transportation departments and industry.
• Task 2 – Develop concrete mixture designs for SCC containing limestone coarse aggregate factoring in both release and 28 day compressive strengths.
• Task 3 – Conduct concrete testing on selected SCC and control mixtures, using both conventional and accelerated curing, as appropriate, including compressive and flexural strengths at 16-18 hours, 3, 7 14 and 28 days, modulus of elasticity at 16-18 hours, 14 and 28 days and shrinkage.
• Task 4 – Develop an instrumentation plan for three girders capable of measuring both instantaneous and time-dependent structural responses.
• Task 5 – Verify through small batch production the mix designs identified in Task 3 using slump flow with VSI (visual stability index), J-ring, L-box, column segregation, and hardened cut cylinders in addition to standard fresh concrete property tests, as suitable for each mix.
• Task 6 – Install instrumentation for each of three girders, two fabricated using SCC and a control.
• Task 7 – Conduct slump flow with VSI (visual stability index), J-ring, and wet concrete property tests during fabrication, as appropriate, demonstrating these procedures to appropriate SDDOT personnel while documenting fabrication process.
• Task 8 – Conduct monotonic increasing load testing on two girders (one control specimen and one SCC specimen) and incrementally increasing cyclic load testing on one SCC girder while collecting data on stress-strain responses in both flexure and shear. Meet with the Technical Panel at the Lohr Structural Laboratory during the testing to discuss interim results and demonstrate the testing procedures.
• Task 9 – Provide an analysis of data for the limestone girder test results along with the results obtained with quartzite girders in prior testing, especially with respect to shear response.
• Task 10 – Evaluate criteria—including constructability, cost, quality, safety, durability, and other appropriate factors—for using SCC in prestressed bridge members in South Dakota and provide a cost/benefit comparison with conventional girder fabrication.
• Task 11 – Develop a Special Provision for Prestressed Concrete using Self-Consolidating Concrete.
• Task 12 – Prepare a final report and executive summary of the literature review, research methodology, findings, conclusions and recommendations.
• Task 13 – Make an executive presentation to the SDDOT Research Review Board at the conclusion of the project.

Contributions/Potential Applications of Research

This research will develop guidelines and specifications for using SCC in construction of bridge girders by SDDOT.

Technology Transfer Activity

At the end of the study, a comprehensive report will be published to document the research procedures and results, and to provide draft specifications and guidelines for use of SCC in prestressed applications in bridge structures. Technical presentations will be offered to bridge engineers and technicians in Region 8 to transfer the knowledge learnt on SCC. Graduate and undergraduate students will also learn about the use and design of SCC mixes and prestressed girders through involvement in the research.

Time Duration

July 1, 2007 – June 30, 2008

Yearly and Total Project Cost

$109,212 Total: $129,904

TRB Keywords

Self-consolidating concrete, self-compacting concrete, SCC, prestressed bridge girders