Title:
Adjustments in Gypsum Content for the Production of Sulfate-Resistant Blended Cements Containing High-Calcium Fly Ash
Author(s):
Reed B. Freeman and Ramon L. Carrasquillo
Publication:
Materials Journal
Volume:
92
Issue:
4
Appears on pages(s):
411-418
Keywords:
blended cements; concretes; durability; fly ash; gypsum; mineral admixtures; pozzolans; sulfate attack; supersulfated cement; X-ray diffraction; Materials Research
DOI:
10.14359/976
Date:
7/1/1995
Abstract:
The use of high-calcium fly ash as a partial replacement for cement may either increase or decrease the sulfate resistance of ASTM Type II cement concrete. These effects of fly ash have been related to, among other factors, changes in the permeability of concrete and in the stability of hydrated calcium aluminates in the presence of sulfate-bearing solutions. The objective of this study was to investigate the effects of adjusting gypsum contents in blended, interground, fly ash cements. The adjustments in gypsum content were expected to influence the sulfate resistance of concrete by increasing the availability of sulfate ions during the hydration of calcium aluminates. In addition to studying the effects of gypsum content on sulfate resistance, its effects on mixing water requirements, compressive strength, and permeability were also examined.