Degree Type

Dissertation

Date of Award

2007

Degree Name

Doctor of Philosophy

Department

Civil, Construction, and Environmental Engineering

First Advisor

Halil Ceylan

Second Advisor

Kejin Wang

Abstract

The work presented in this Dissertation involves an effort to broaden sustainable applications (e.g., recycling waste material in concrete, reducing CO2 emissions in cement production) in construction industry. Finely ground brick obtained from demolished masonry was evaluated as a pozzolanic cementitious material in concrete. The hydration characteristics of this material and its effects on cement paste, mortar, and concrete mechanical properties, particularly on alkali-silica reaction deterioration was studied. Ground clay brick (GCB) was produced in the laboratory employing a ball mill. Chemical and physical properties comply with the designated ASTM standard that defines pozzolanic materials. The results of the study on cementitious pastes where cement was replaced by GCB up to 25% showed that the effect on water demand for normal consistency and time of setting was insignificant; the temperature rise during hydration was reduced; and the calcium hydroxide production was decreased. The testing of mechanical properties of concrete containing up to 25% GCB demonstrated that the values were low at early age but higher or comparable at later ages when compared to the control and the resistance to chloride penetration was improved. These results suggested a pozzolanic activity provided by finely ground brick. The results from the accelerated ASR testing of mortar mixtures showed that the expansions were significantly reduced and associated deterioration on the compressive and flexural strengths was limited with the use of GCB. The concrete tests confirmed the mortar testing that the expansion was effectively suppressed and the mechanical properties of a highly alkali-silica reactive mixture could be conserved when cement was replaced by GCB at 15 and 25% loading. Subsequent microstructural study revealed out the quantitatively low gel formation in the presence of GCB and further suggested a modification in gel chemistry by GCB. The reported experimental study demonstarted that GCB shows pozzolanic behavior similar to other conventional materials (e.g., fly ash, calcined clay, or natural pozzolan), and it can be used as a supplementary cementitious material in concrete applications. Use of GCB in concrete can effectively reduce the alkali-silica reaction deterioration in concrete.

DOI

https://doi.org/10.31274/rtd-180813-6631

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu

Copyright Owner

Fatih Bektas

Language

en

Date Available

June 1, 2013

Proquest ID

AAI3289372

OCLC Number

221625647

ISBN

9780549334897

File Format

application/pdf

File Size

149 pages

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