PRESTRESSED CONCRETE COMMITTEE FOR ECONOMICAL FABRICATION

**MEETING MINUTES**

**FEBRUARY 13, 2003**

**HOLIDAY INN CHARLESTON HOUSE -- CHARLESTON, WV**

# CALL TO ORDER AND INTRODUCTIONS

The chairman, Mr Lou Triandafilou, called the meeting to order by
welcoming all attendees. All attendees were asked to make
self-introductions.

A copy of the committee's current "Mailing List" was circulated for
everyone to review and verify that the information contained on the list
was correct and to make corrections as necessary. New attendees were
encouraged to add their names and addresses to the list. Also circulated
was the "List of Subcommittees" where everyone, especially first-time
attendees, was asked if they were not currently serving on a
subcommittee, but would be interested in serving, to please add their
name and address.

Mr Triandafilou again mentioned that we are lacking chairpersons for the
subcommittees on Production/Construction and Design Parameters. He also
mentioned the possibility of combining them with other closely related
subcommittees.

## APPROVAL OF MINUTES FROM LAST MEETING

> Mr. Triandafilou asked if there were any additions or deletions to the
> minutes of the April 4, 2002 meeting held in West Atlantic City, NJ.

A motion was made, seconded and carried to accept the minutes as
written.

I.  **USE OF NATURAL POZZOLAN TO ENHANCE THE PROPERTIES OF
    SELF-CONSOLIDATING CONCRETE**

Mr. Chris Dumas was unable to attend and give his presentation on the
International Use of Self-Consolidating Concrete (SCC). In his absence,
Mr. Paul Ramsburg of Rotundo Precast, Inc./Oldcastle, Inc. gave an
informative presentation on the use of natural pozzolans to enhance the
properties of SCC. Some of the highlights of his talk included:

-   Use of SCC in precast products is widely expanding in the U.S.,
    while the Europeans are using it more in ready-mix applications.
    Plants in Baltimore and Manchester, NY have used SCC in prestressed
    box beams.

> VDOT noted that a Bebo arch recently built using SCC had a cleaner
> appearance than 1 cast with conventional concrete.

-   SCC performs well under durability, bond and shrinkage tests, and
    shows little difference in hardened properties from conventional
    concrete. Big advantages are with easier and faster placement, less
    labor and equipment needed.

-   40 out of 70 plants that Oldcastle deals with are using viscosity
    modifying agents

Since Mr. Ramsburg's presentation did not address the issue of
permeability, Messrs. Triandafilou and Napier requested that he provide
any information available regarding these issues. Messrs. Potter and
Tucker asked about development length studies (strand pull-out tests)
that have been conducted on strands used in SCC. Mr Ramsburg stated that
he was not aware of any studies conducted as of yet on development
lengths. He stated that this is an area which would require future
investigation.

A copy of the First North American Conference on the Design and Use of
Self-Consolidating Concrete's November 12-13, 2002 Conference
Proceedings was given to all in attendance.

II. **STATUS REPORT FROM THE STATES ON USE OF THE PCEF BULB-T SHAPES AND
    IMPLEMENTATION OF HPC**

NCDOT completed a 4-span bridge using 10 ksi HPC in AASHTO Modified
bulb-Ts; 1 line of girders was instrumented. (A CD of the project is
available). Deck cracking was an issue, mainly in the negative moment
areas over the piers, and they are investigating causes. They also
completed a 5.2-mile long bridge with 230' center spans, using over 1800
AASHTO modified beams with 7--8 ksi compressive strengths. Only minor
deck cracking was evident in the end spans. The State has yet specified
the PCEF bulb-t shapes but will investigate their use on future
projects.

DelDOT likes the PCEF bulb-T concept, and is still looking for their
first application. They have completed 2 bridges that consist of all-HPC
elements, plus 1 bridge with a HPC superstructure. They have also
constructed HPC deck overlays. They allow lower temperatures for deck
placements, and that practice has resulted in little or no deck
cracking.

WVDOT has formed an in-house committee to investigate future use of the
PCEF bulb-Ts. They have built a limited number of full-depth HPC decks,
some overlays and at least 1 superstructure project. They have initiated
a research with WVU to evaluate HPC mixes.

> MDSHA has 1 project under design using the PCEF bulb-t shapes. They
> completed their first HPC deck 2-1/2 years ago with excellent results
> (little or no cracking using fibers and fly ash). They have an
> upcoming re-decking project of a 110' span bridge, using lightweight
> HPC. The Woodrow Wilson Bridge replacement calls for lightweight
> concrete in the bascule span deck, and used HPC in the mass concrete
> placements for the V-pier foundations. Lightweight concrete slabs are
> also being used at the BWI Airport project. The March 3^rd^ MD
> Concrete Conference was announced **(Note: the event was excellent).**

NYSDOT stated that they are continuing to design with the New England
bulb-Ts (metric units). A hard conversion to English units makes them
very similar in shape to the PCEF bulb-t shapes; therefore,
Contractor-proposed substitutes are acceptable. They have completed 4
PCEF bulb-T projects using HPC, one using spliced girders. Three more
projects are currently under review. Fabrication experiences have been
mostly positive, with some end cracking. All cast-in-place decks have
been HPC since about 1996. An internal task force is looking into deck
cracking issues, while a university is studying creep, shrinkage and
thermal properties of HPC mixes. Fourteen bridges have been built with
HPC beams, and 25 more are planned this summer. Four precasters have
approved HPC mix designs, using 0.32 w/c. 56-day compressive strengths
have been required for beams; in some cases these later strengths have
been lower than measured 28-day strengths (causes still unknown). Costs
of HPC beams have been comparable to conventional beams. DCI corrosion
inhibitor and silane is used, along with blended cements.

> PennDOT stated that prestressed concrete suppliers wrote to the
> Department stating they would like to move forward with implementing
> PCEF bulb-t shapes, holding the 8" web thickness that the state
> prefers. Schuylkill Products currently has the forms for these shapes,
> and another supplier is ordering the forms. The State has been using 8
> ksi in their beams for about 15 years, with a Penn State study
> underway to increase strengths. Deck cracking has been a problem on
> some early projects, but probably not due to the HPC mix. Their 4000
> psi deck designs have typically been achieving 9000 psi. The State is
> considering lowering the specified strength to 3000 psi and placing a
> 6000 psi upper limit, in order to reduce cracking.

VDOT has incorporated a set of nine PCEF bulb-t shapes as their standard
bulb-t shapes for sometime now. Projects in the state where prestressed
concrete beams are appropriate will utilize these shapes. One exception
would be bridges on a sharp skew, where cracking problems have been
noted where thick closure diaphragms frame into beam ends. VDOT has
several projects currently underway utilizing the PCEF bulb-t shapes,
including some with spliced haunches.

All states are either using or considering the use of high performance
concrete (HPC). Several states using HPC in concrete decks expressed
problems with deck cracking. It was noted that the Ohio DOT performed a
detailed study of several years of deck placements. A definitive result
was that decks placed with coarse aggregate containing \>1% absorption
rate showed little or no cracking. Decks containing aggregates with \<1%
absorption showed extensive cracking. They plan to revise their mix
design specs accordingly. NYSDOT is very interested in this finding, and
will investigate their own experiences further.

III. **UPDATE ON GROUTING ISSUES FOR POST-TENSIONED CONCRETE BRIDGES**

Mr. Jerry Potter of the FHWA gave an update on the work he is doing with
regards to grouting issues for post tensioned concrete bridges. These
issues apply to any concrete superstructure with post-tensioned
conditions, and not only segmental box girder structures. A handout was
distributed.

Mr Potter briefly went over the handout containing information provided
by numerous states regarding the condition of tendons in their
post-tensioned bridges. Probable causes for tendon corrosion include:
use of high bleed grout; poor design details; relaxed inspection
oversight; relaxed construction and grouting operations; weak
construction specs.

Mr. Potter finished his presentation by discussing continuing actions to
help resolve the grouting issues in connection with post-tensioned
tendons. Vacuum grouting is considered more effective for small voids,
compared to pressure grouting. Also, the flow cone test is considered
unnecessary.

IV. **SUBCOMMITTE STATUS REPORT**

    A.  **Materials and QC/QA Subcommittee**

> It was mentioned that the Guide Specification for QC/QA Manual which
> had previously been adopted by PCEF Committee member states is ready
> for publication. A hard copy and a copy on a CD will be provided to
> each member state.
>
> The next tasks to be undertaken by this subcommittee will be to look
> into developing a set of regional acceptance program
> guidelines/specifications for use of self-consolidating concrete, and
> specifications for grouting materials and operations for spliced
> girders.
>
> Mr. Triandafilou once again brought up the fact that a chairman is
> needed for the Production and Construction Subcommittee, to oversee
> development of regional criteria for such items as prestressed
> concrete beam plant inspection, beam handling, storage and erection.
> He also brought up the idea of combining this subcommittee with the
> Materials and QC/QA Subcommittee. After a short discussion, it was
> decided to combine both subcommittees into one.

B.  **Design Parameters and Standardization Subcommittee**

> Mr. Claude Napier, co-chairman, mentioned that only old business the
> Standardization subcommittee has remaining is the issue of diaphragms
> (to include closure diaphragms) as pertaining to their details,
> spacing and for use on skewed bridges. Mr. Joseph Tucker suggested
> adding topics for skewing the ends of beams and continuity design.
>
> Mr. Napier stated that this subcommittee will also start looking into
> developing recommended anchorage details for splice girders, based on
> NCHRP recommendations. Other possibilities include deck pouring
> sequences, and any other pertinent topics included in the original
> PCEF survey.
>
> Now that the Design Parameters subcommittee has been combined with the
> Standardization subcommittee Mr. Napier stated his committee will also
> be looking into the issue of debonding of strands to include coming up
> with a recommended maximum number of debonded strands and any other
> necessary criteria for the use of debonded strands.
>
> Mr. Napier added that this subcommittee will have the industry respond
> to the issues of design parameters by setting a priority to the ones
> developed by the former subcommittee chairman.

V.  **PRECAST CONCRETE ELEMENTS**

At previous meetings, there has been little interest expressed by the
member states regarding the PCEF Committee being involved with precast
concrete elements. Still keeping this topic on a very informal basis,
Mr. Finnerty offered to distribute a survey to the member states, to at
least solicit information on their current acceptance criteria for these
elements; whether or not they see any benefits in participating in a
regional acceptance program for structural precast products, and if not,
why not.

VI. **OTHER ISSUES**

The next meeting of the PCEF Committee will be scheduled for sometime in
late August/early September of 2003. The exact date and location of this
meeting to be determined and announced at a later date.

VII. **ADJOURNMENT**

> .