Date of Graduation

8-2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Civil Engineering

Advisor

W. Micah Hale

Committee Member

Gary Prinz

Second Committee Member

Mark Arnold

Third Committee Member

Thano Drimalas

Fourth Committee Member

Benoit Fournier

Fifth Committee Member

Eric Giannini

Keywords

Alkali-Silica Reaction (ASR), Concrete Materials, Durability, Freezing and Thawing, Mechanism, Mitigation

Abstract

An evaluation of alkali-silica reaction (ASR) and freezing and thawing (F/T) in concrete transportation structures is presented along with mitigation methods for slowing the rate of deterioration in concrete. A combination of field and laboratory testing confirms ASR deterioration is exacerbated by exposure to F/T. Laboratory testing indicates an aggregate previously deemed inert to ASR, caused ASR deterioration in several concrete pavement and transportation structures. Existing standard test methods deem this aggregate safe for use in concrete. A modified test method shows the concrete can deteriorate rapidly when subjected to cycles of conditions promoting ASR and F/T. Several structures containing this aggregate deteriorated rapidly and severely during exposure to F/T. The interstate pavement underwent less deterioration as the incorporation of some Class C fly ash limited the development of ASR, and improved the durability to F/T. A three-year field test of various treatments applied to concrete barriers indicates silane reduces the moisture state of the concrete and slows the development of F/T and ASR deterioration as compared to untreated sections. A corresponding three-year evaluation of silane applied to concrete pavements, indicates silane slows F/T deterioration over time by reducing the moisture state of the concrete.

Measuring the moisture state of concrete in the field proved difficult. Results of field and laboratory testing indicate measuring vapor pressure may prove more useful for evaluating the efficacy of treatments in reducing the moisture within concrete. The moisture state of the concrete is critical to the development of both ASR and F/T, as concretes protected from external moisture did not develop deleterious deterioration while specimens exposed to additional moisture deteriorated. This indicates limiting the ingress of external moisture is a viable method for slowing both ASR and F/T deterioration in concrete.

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