Environmental and Reinforcement Effects on Concrete Expansion Undergoing Accelerated Alkali-Silica Reaction

Graff, David

Graduate Thesis Or Dissertation

Environmental and Reinforcement Effects on Concrete Expansion Undergoing Accelerated Alkali-Silica Reaction Público Deposited

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/6t053g395

Abstract

This thesis is a part of ongoing research investigating the effects of alkali-silica reactions (ASR) on concrete’s mechanical properties. Over 50 concrete specimens have been cast and cured to encourage ASR development to the point of damage in less than a year. Specimens include 42”×30”×10” shear specimens, 14”×14”×14” blocks, 6”×6”×14” prisms, 4”×4”×16” prisms, cylinders, and wedge splitting test specimens. Some samples are stored in a fog room with conditions of 100oF, and 95% relative humidity and wrapped in burlap wetted or submerged in 1.0M sodium hydroxide (NaOH). Other specimens are stored in the lab at ambient temperature submerged in the same NaOH solution. Shear specimens, blocks, and prisms are outfitted with datum discs and their expansion is tracked through regular measurements. Specimens are cast with various reinforcements to investigate how the presence of reinforcement and the reinforcement ratio influences the amount of ASR swelling. About half of the blocks and prisms are stored outside of the fog room to examine the temperature effects on ASR expansion. When comparing similar specimens with varying reinforcements and temperature, results of shear specimens and prisms show that increasing reinforcement ratios will constrain ASR expansion. Also, prisms stored outside the fog room also exhibit restricted expansion. However, blocks have results that are less consistent with predictions. Blocks expansion does not follow the trend of less expansion with increasing reinforcement ratios. A relatively small number of specimens with a variety of reinforcement configurations in varying temperatures may have too many outside variables to show clear results. Additionally, blocks stored at ambient temperatures show more expansion than those stored at high heat in the fog room. It is speculated that this is because blocks were submerged in NaOH outside the fog room and wrapped in burlap and wetted for logistical reasons.

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