Title:
Residual Strength of Reinforced Concrete Beams Damaged by Alkali-Silica Reaction—Examination of Damage Rating Index Method
Author(s):
L. J. Monette, N. J. Gardner, and P. E. Grattan-Bellew
Publication:
Materials Journal
Volume:
99
Issue:
1
Appears on pages(s):
42-50
Keywords:
alkali-silica reaction; concrete; expansion; reinforced concrete.
DOI:
10.14359/11315
Date:
1/1/2002
Abstract:
Estimating the residual strength of structural members affected by alkali-silica reaction (ASR) is a significant problem. Small-scale, singly reinforced concrete beams, concrete cylinders, and prisms made with reactive and nonreactive aggregates and high-alkali cement, were stored submerged in a high-alkali solution at 38 C to accelerate the ASR. Beams were conditioned either without load, under sustained load, or under cyclic load. Beam and cylinder expansions were measured. After significant expansion, both sides of each reactive aggregate beam and one reactive aggregate resonant frequency prism were polished and examined under a microscope for features consistent with damage due to ASR. These features were tabulated to determine the damage rating indexes (DRIs) of the various specimens. After measurement of the DRIs, the various reactive and nonreactive specimens were loaded to failure. Sustained and cyclic flexural load and the longitudinal reinforcement had significant restraining effects on ASR expansions. The DRIs did represent, approximately, the measured expansions. Flexural tests to failure showed that neither ASR expansions nor load conditioning significantly affected the stiffnesses and load-carrying capacities of the reactive concrete beams. Material tests showed that ASR reduced the compressive stiffness, resonant frequency, and flexural strength of the concrete, but not the compressive strength. The test specimens were conditioned submerged in a one normal sodium hydroxide solution and not subject to cycles of wetting and drying as would occur in practice. The DRI of the concrete prism correlated with the loss in stiffness, resonant frequency, and flexural strength.