Fracture mechanics of ASR in concretes with waste glass particles of different sizes

Zdeněk P. Bažant, Goangseup Zi, Christian Meyer

Research output: Contribution to journalArticle

76 Citations (Scopus)

Abstract

Using waste glass as an aggregate in concrete can cause severe damage because of the alkali-silica reaction (ASR) between the alkali in the cement paste and the silica in the glass. Recent accelerated 2-week tests, conducted according to ASTM C 1260, revealed that the damage to concrete caused by expansion of the ASR gel, which is manifested by strength reduction, depends in these tests strongly on the size of the glass particles. As the particle size decreases, the tensile strength first also decreases, which is expected because of the surface-to-volume ratio of the particles, and thus their chemical reactivity increases. However, there exists a certain worst (pessimum) size below which any further decrease of particle size improves the strength, and the damage becomes virtually nonexistent if the particles are small enough. The volume dilatation due to ASR is maximum for the pessimum particle size and decreases with a further decrease of size. These experimental findings seem contrary to intuition. This paper proposes a micromechanical fracture theory that explains the reversal of particle size effect in the accelerated 2-week test by two opposing mechanisms: (1) The extent of chemical reaction as a function of surface area, which causes the strength to decrease with a decreasing particle size; and (2) the size effect of the cracks produced by expansion of the ASR gel, which causes the opposite. The pessimum size, which is about 1.5 mm, corresponds to the case where the effects of both mechanisms are balanced. For smaller sizes the second mechanism prevails, and for sizes <0.15 mm no adverse effects are detectable. Extrapolation of the accelerated test (ASTM C 1260) to real structures and full lifetimes will require coupling the present model with the modeling of the reaction kinetics and diffusion processes involved.

Original languageEnglish
Pages (from-to)226-232
Number of pages7
JournalJournal of Engineering Mechanics
Volume126
Issue number3
DOIs
Publication statusPublished - 2000 Mar 1
Externally publishedYes

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Fracture mechanics
Particle size
Silica
Concretes
Glass
Gels
Chemical reactivity
Extrapolation
Reaction kinetics
Chemical reactions
Cements
Tensile strength
Cracks

ASJC Scopus subject areas

  • Mechanical Engineering

Cite this

Fracture mechanics of ASR in concretes with waste glass particles of different sizes. / Bažant, Zdeněk P.; Zi, Goangseup; Meyer, Christian.

In: Journal of Engineering Mechanics, Vol. 126, No. 3, 01.03.2000, p. 226-232.

Research output: Contribution to journalArticle

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