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Accession Number PB2013-102445
Title Accelerated Assessment of ASR Damage by Nonlinear Ultrasonic Method.
Publication Date Oct 2012
Media Count 20p
Personal Author J. Qu
Abstract Alkali-silica reaction (ASR) is a deleterious chemical process that may occur in cement-based materials such as mortars and concretes, where the hydroxyl ions in the alkaline solution attack the siloxane groups (Si-O-Si) of the siliceous mineral components in the aggregates. Aggregates containing siliceous minerals are known to be particularly susceptible to this reaction. Hydroxyl ions together with alkali metal cations (sodium or potassium) bind with siliceous species derived from the reactive minerals to form a cross-linked alkali-silica gel. The alkali-silica gel swells in the presence of water from the surrounding material. Expansion of the gel results in cracking when the swelling stress exceeds the tensile strength of the paste or aggregates. As expansion increases, cracks grow and eventually coalesce; the strength and modulus of the material are decreased and the permeability is increased. The cracking produced by ASR can significantly undermine the durability of concrete structures and may result in reduced service life.
Keywords Aggregates
Alkali silicia reaction
Cations
Cements
Chemical processing
Concrete durability
Cracking (Fracturing)
Damage
Gels
Hydroxyl ions
Minerals
Mortars
Service life
Tensile strength
Ultrasonic method

 
Source Agency Department of Transportation Office of University Research
NTIS Subject Category 50C - Construction Equipment, Materials, & Supplies
50A - Highway Engineering
89G - Construction Materials, Components, & Equipment
Corporate Author Northwestern Univ., Evanston, IL. Infrastructure Technology Inst.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1303
Contract Number N/A

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