Deterioration of Precast Concrete Panels with Crushed Quartz Coarse Aggregate due to Alkali-Silica Reaction

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Title: Deterioration of Precast Concrete Panels with Crushed Quartz Coarse Aggregate due to Alkali-Silica Reaction

Author(s): Michael A. Ozol and Donald O. Dusenberry

Publication: Special Publication

Volume: 131

Issue:

Appears on pages(s): 407-416

Keywords: alkali content; alkali-silica reactions; concrete panels; corrosion; cracking (fracturing); deterioration; freeze-thaw durability; petrography; quartz; repairs; spalling; General

Date: 3/1/1992

Abstract:
Five dormitory buildings on the Amherst College campus in Amherst, Massachusetts have essentially identical exposed aggregate precast concrete curtainwall panels. The panels on the three buildings that were constructed in 1963 are severely cracked and spalled; the buildings constructed in 1964 are relatively free of deterioration. The concrete used in the panels of all the buildings is composed of crushed quartz coarse and fine aggregate with strong and hard portland cement paste with low water-cement ratio and low void content. The significant difference between the materials used in the buildings is the amount of alkalies: the alkali content of the portland cement in the 1963 buildings is almost twice as high as in the 1964 buildings. A network of fine cracks developed in the panels due to alkali-silica reaction. These cracks allowed water to enter the panels and freeze during cold weather. The resulting progressive damage has led to disintegration of the cement paste, severe spalling, and corrosion of the reinforcing steel. The phased repair program, which began in the summer of 1989 and is expected to require several years to complete, involves removal and/or replacement of severely damaged panels, repair of damaged panels in place, modification of structural and waterproofing details to reduce exposure, and treating of undamaged panels to prolong their life.