Title:
Effective Alkalies from Pulverized Fuel Ash, Granulated Blast Furnace Slag and Natural Pozzolana Deduced from Mortar Bar Expansion Results
Author(s):
J. J. Kollek
Publication:
Symposium Paper
Volume:
114
Issue:
Appears on pages(s):
373-402
Keywords:
alkali-aggregate reactions; alkalies; binders (materials); blast furnace slag; expansion; fly ash; grinding (comminution); mortars (material); pozzolans; Materials Research
DOI:
10.14359/2046
Date:
5/1/1989
Abstract:
A study was conducted to determine whether pulverized fuel ash, granulated blast furnace slag, and natural pozzolana contribute effective alkalies and whether such alkalies lead to alkali-silica reaction (ASR) damage. Mortar bars were prepared in accordance with ASTM C 227 but stored at 20 C, and using three factory-produced cements, three Type F pulverized fuel ashes, three blast furnace slags, and four natural pozzolans at three or four different levels of substitution. The reactive aggregate component was Beltane opal substituted at the pessimum level, as well as zero and three near-pessimum levels. The selection of the materials and their substitution levels were adjudged to represent as wide as possible present-day usage. Deleterious expansion defined as > 0.0 percent within 4 years was taken as the criterion of failure. The results have been applied to demonstrate the deduction of practical guidelines for the use of composite hydraulic binders in situations in which ASR is a consideration. Limiting total alkali contents of composite hydraulic binders as function of the substitution ratio of the three mineral additives are suggested. The analysis of the results demonstrates that if the effective alkalies derived from portland cement are taken as 100 percent, then those derived from pulverized fuel ash and natural pozzolana can be taken as 17 percent and those derived from blast furnace slag as 50 percent of total alkalies. There is also evidence of somem mineral additives, particularly at high substitution levels, not simply acting as dilutents but exhibiting a positive ASR-suppressive effect.