Doctoral Dissertations

Keywords and Phrases

Freeze-Thaw; Pumping; Rheology; Self-consolidating concrete; Workability

Abstract

“The durability of concrete must be ensured to reduce the carbon footprint of the production of portland cement. If concrete is properly designed to preserve its integrity under adverse exposure conditions, the service life of the material can be extended with minimum maintenance. Nevertheless, bad handling, placing, finishing or curing practices can abate the durability potential and service life of even the best mix design. Pumping concrete is a very efficient placing technique that offers significant cost reduction and versatility at the jobsite, but it also has the potential of altering the air void system parameters, which are key to guarantee proper durability under cold weather conditions. This research has as main goal to expand the current knowledge related to the behavior of the air-void system of highly flowable concrete (HWC), including SCC, when its pumped. Nine large-scale pumping campaigns were performed on 18 concrete mixtures exploring the effect flow rate, boom position, mix composition and workability had on the spacing factor, and how these factors related to frost durability. In addition, the capability of rheology to understand air dissolution and reappearance in cement paste under combined action of pressure and flow were assessed. It was found that the changes in the spacing factor and fresh state properties did not correlate with a single pumping parameter. Instead, many parameters played a significant role simultaneously. The tests conducted on cement paste under pressure revealed that the shear rate, bubble size distribution and duration of pressure application play a major role on the dissolution and reappearance of air bubbles, where shear rates in the order of 100 s-1 affect the most the bubble size distribution”--Abstract, page iv.

Advisor(s)

Feys, Dimitri

Committee Member(s)

Riding, Kyle A.
Khayat, Kamal
Abdelrahman, Magdy
ElGawady, Mohamed

Department(s)

Civil, Architectural and Environmental Engineering

Degree Name

Ph. D. in Civil Engineering

Comments

The authors would like to acknowledge the American Concrete Institute’s Concrete Research Council and the US Department of Transportation Tier-1 UTC (RE-CAST) at Missouri S&T for the financial support.

Research Center/Lab(s)

Re-Cast Tier1 University Transportation Center

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2020

Journal article titles appearing in thesis/dissertation

  • Characterization of air dissolution and reappearance under pressure in cement pastes by means of rheology
  • The influence of shear rate and bubble size distribution on the rheology of pressurized air-entrained cement paste
  • Influence of pumping parameters on the air-void system of highly workable and self-consolidating concrete
  • Why changes in air content due to pumping are not good indicators of final flowable concrete frost-related durability properties

Pagination

xviii, 176 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2020 Daniel Galvez Moreno, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 11976

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