Interactive Panel Proceedings

from the

First International Interactive Symposium on Ultra-High Performance Concrete

July 18-20, 2016 Des Moines, Iowa, USA

INTERACTIVE PANEL 6 Mixture Proportioning

Panel Chairs: Brian H. Green, R.P.G., FACI, U.S. Army Engineer Research and

Development Center and Kay Wille, Ph.D., C.E., University of Connecticut

Expert Panel Members:

Dominique Corvez, Head of Ductal® Americas, Lafarge North America, a member of LafargeHolcim

Brad Weldon, Ph.D., Assistant Professor, New Mexico State University

Zhengyu Huang, C.E., Professor, Hunan University, China

Kay Wille, Ph.D., Associate Professor, University of Connecticut

Panel Interactivity Administrator: Interactive Panel Synopsis Report Kay Wille Authored by: Kay Wille

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Interactive Panel Interactive Panel 6: Mixture Proportioning

Co-chaired by Brian H. Green from the U.S. Army Engineer Research and Development Center (ERDC) and Kay Wille from the University of Connecticut (UConn), this interactive panel, comprised of panel experts from Lafarge North America, a member of LafargeHolcim, New Mexico State University, Hunan University (China) and UConn, provides a valuable perspective on the mixture proportioning of ultra-high performance concrete (UHPC). The topics include: robustness of UHPC in field implementation; the use of local available materials; performance based design; and the design of paste, matrix and composite UHPC.

Panel 6, "Mixture Proportioning", began with the following introductory presentation by Brian Green.

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Prior to opening the interactive portion of the session, short presentations were delivered by each panel member to provide background and motivate audience questions. Panel member names, affiliations, and presentation titles are listed below:

1. Dominique Corvez, Ductal® Americas, Lafarge North America, a member of LafargeHolcim: Robustness of UHPC Production on Site - pg. 3

2. Brad Weldon, New Mexico State University: Ultra-High Performance Concrete in New Mexico - pg. 4

3. Zhengyu Huang, Hunan University, China: Proportioning of UHPC Based on Performance - pg. 5

4. Kay Wille, UConn: Mix Proportioning of UHPC; Which Way to Go? - pg. 8

The Interactive Panel received questions from the audience via live audience interaction software and direct participation to engage in a panel discussion based on that input. This State-of-the-Art Report provides copies of each presentation, along with brief summaries. A partial list of transcribed questions from this session is provided in Appendix A.

1. Presentation by Dominique Corvez: Robustness of UHPC Production On Site

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Mr. Corvez shared experiences with respect to field-cast UHPC applications on 200

+ bridge projects over

the past 4 years. (See Figure 1 for examples of UHPC on-site mixing, as well as delivery and casting via ready mix truck.) He stressed the importance of sourcing high quality materials; the use of external quality control services; and the benefits of premixed, pre-bagged materials. Robust UHPC mix design is just one part of large-scale, robust application of UHPC. He also stressed the importance of working with the right people, such as those who have the ability to influence successful application(s) of UHPC.

(a) Onsite mixing (b) Delivery and casting

Figure 1. Onsite mixing and site delivery of UHPC

2. Presentation by Brad Weldon: Ultra-High Performance Concrete in New Mexico

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Dr. Weldon’s research group at New Mexico State University designed a UHPC using locally sourced materials. Performance criteria included economy, strength, durability and precast familiarity. The partial replacement of silica-fume with flyash was one approach (among others) that was tested, in order to achieve their target results. See Figure 2 shows (a) a UHPC cross-section and (b) Fiber bridging; the samples were produced with locally-available materials.

(a) UHPC cross-section (b) Fiber bridging

Figure 2. UHPC made with local available materials

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3. Presentation by Zhengyu Huang: Proportioning of UHPC Based on Performance

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Professor Huang presented the proportioning of UHPC, based on performance criteria that included workability, mechanical properties, dimensional stability, durability and economy. The UHPC mixture design was based on the principles of maximized packing density, optimized microstructure, homogenized compositions and fiber toughness.

During the second part of his presentation, Professor Huang highlighted some applications of UHPC in China, such as the Dongting Lake Bridge, shown in Figure 3.

Figure 3. Dongting Lake Bridge,1480 + 453.6m (2017)

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4. Presentation by Kay Wille: Mix proportioning of UHPC. Which way to go?

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Dr. Wille presented an overview of preferable properties of material constituents in the UHPC mix design and highlighted the link between matrix flowability and particle packing density. Based on this approach, he then presented the mechanical properties of an optimized UHPC matrix, combined with tailored fiber reinforcement, leading to strain-hardening UHPC, for example; with a tensile strength of 30 MPa and 3% volume of steel fibers. (See Figure 4, "Level dependent UHPC design".) In the second part of this presentation, Dr. Wille revealed research results for the mixture design of cost-efficient UHPC, using locally sourced materials. The mixture design evaluation was led by an efficiency factor influenced by strength, workability and costs. In conclusion, the question was raised; in which direction should UHPC design go in the future? He further explained that evaluation criteria would have to include numerous factors such as: economics; feasibility; high-quantity availability; customized particle size distribution; material quality and control; and quality of dispersion of all constituents.

Figure 4. Level dependent UHPC design

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APPENDIX A – Interactive session

Below is a partial list of audience questions selected for discussion during this session.

Question

Has any work been done regarding: microbial-induced corrosion in sanitary sewer environments; and

additives that would improve performance?

How much space between rebar is needed for consistent fiber dispersion?

How do you handle 100 degree temperatures to avoid loss of workability and moisture?

How do you address variability in the local raw materials (i.e., flyash) when producing a local UHPC

mixture? Would the system be robust enough?

Which ASR test did you run?

Is ASR a problem if microsilica content is higher than 5% of cement content?

Can one of the speakers shed light on creep characteristics of UHPC?

What fiber geometry provides the most strength in UHPC?

Has anyone tried using PLC cements that have interground limestone content?

Is it feasible to eliminate silica fume?

Which constituents allow the greatest variability in terms of particle size and shape, without affecting

performance?

Has any work been done with modeling on "mass pours" with UHPC mixes?