Abstract

The use of mineral admixtures and fibers is becoming essential in the new generation of high performance concrete since they introduce enhancement in mechanical properties as well as several durability aspects. Some of the advantages gained when properly employing high performance concrete are significant improvements in strength, drastically reduced permeability, better resistance to a wide spectrum of chemicals, superior performance in freezing and thawing conditions and enhanced thermal resistance. Although silica fume and polypropylene fibers are increasingly used in high performance concrete, yet, relatively little work has focused on the interaction of both ingredients in such concretes. The main aim of this work is to investigate the interaction between silica fume and polypropylene fibers through studying key concrete properties. Conventional and high performance concrete mixtures were prepared using water to cementitious materials ratio's of 0.35, 0.40 and 0.50. Polypropylene fibers were added at dosages of 0.1, 0.3 and 0.5% by concrete volume while silica fume has been added at 10 and 15% mass replacement of Portland cement. Workability, compressive, flexural and splitting strength tests were performed on concrete. Fracture parameters were studied through testing notched beams and analyzing fracture toughness parameters. In terms of durability, permeability characteristics as well as chemical soundness of concrete were investigated. Moreover, drying shrinkage and resulting cracking patterns were also studied through monitoring cracking pattern of restrained concrete plates that were subjected to both thorough curing and air curing in hot weather. This investigation reveals that many concrete properties are dosage-sensitive for both the silica fume and the fibers. In fact, properties such as the flexural strength and shrinkage are more dependent on one of the two ingredients than the other. On the whole, strength was improved as a result of adding appropriate dosages of both silica fume and fibers. However, both ingredients result in some loss in slump. Due to the exhibited results, new formulae were suggested herein for the prediction of the modulus of rupture. Results indicate enhanced performance against chemicals and reduced permeability for most of the high performance mixtures covered. Characteristic cracking patterns have been identified for those mixtures made with silica fume and those made with fibers.

Date of Award

6-1-2002

Online Submission Date

1-1-2002

First Advisor

Mohamed Nagib Abou-Zeid

Second Advisor

Ezzat Hassan Fahmy

Committee Member 1

Mohamed Nagib Abou-Zeid

Committee Member 2

Moustafa El Demirdash

Committee Member 3

Safwan Khedr

Document Type

Thesis

Extent

248 leaves :

Library of Congress Subject Heading 1

Silica fume.

Library of Congress Subject Heading 2

Polypropylene.

Rights

The author retains all rights with regard to copyright. The author certifies that written permission from the owner(s) of third-party copyrighted matter included in the thesis, dissertation, paper, or record of study has been obtained. The author further certifies that IRB approval has been obtained for this thesis, or that IRB approval is not necessary for this thesis. Insofar as this thesis, dissertation, paper, or record of study is an educational record as defined in the Family Educational Rights and Privacy Act (FERPA) (20 USC 1232g), the author has granted consent to disclosure of it to anyone who requests a copy.

Call Number

Thesis 2002/44

Location

mgfth

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