Masters Theses

Keywords and Phrases

Air-Void System; Durability; Freeze-Thaw; Pumping; Scaling; Self-Consolidating Concrete

Abstract

“Over the past 60 years, pumping concrete has gained popularity due to the economic and technical benefits that typically accompanies it. However, boom configuration and flow rate can adversely affect freeze-thaw and scaling resistance of concrete due to the effects of pressure on the air-void system. Therefore, the objective of this research is to assess the influence of different pumping parameters on the durability of hardened self-consolidating concrete. Self-consolidating, flowable, and conventional concrete mixtures were tested during large scale pumping experiments positioning the pump boom in an “A” and a flat shape as well as using different pumping speeds. In addition, the effect of adding a reducer and submerging the discharge hose into concrete to minimize the impact on the concrete air-void system was also explored. While pumping, the concrete fresh properties, including the air content were measured. The freeze-thaw durability and scaling resistance were tested for both pumped and non-pumped samples. Furthermore, the air-void size distribution in the hardened state was measured. During pumping, considerable changes in fresh air content were observed from sample to sample. Hardened results indicated that different pumping parameters induced different changes in the air-void system, most importantly the spacing factor. The most notable increases in spacing factor were observed when increasing the flow rate in the A configuration for self-consolidating and flowable mixtures and adding a reducer in the A configuration with self-consolidating concrete. The changes in air-void system corresponded to changes in the severity of scaling. A poor air-void system led to lower scaling resistance. Mixtures with higher air content showed fewer signs that pumping affects the freeze-thaw or scaling resistance”--Abstract, page iii.

Advisor(s)

Feys, Dimitri

Committee Member(s)

Riding, Kyle A.
ElGawady, Mohamed

Department(s)

Civil, Architectural and Environmental Engineering

Degree Name

M.S. in Civil Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2019

Pagination

xii, 141 pages

Note about bibliography

Includes bibliographic references (pages 134-140).

Rights

© 2019 Alexandra Nicole Wehar, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Thesis Number

T 12064

Electronic OCLC #

1313117359

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