Title:
Chemically Activated Blended Cements
Author(s):
Zichao Wu and Tarun R. Naik
Publication:
Materials Journal
Volume:
100
Issue:
5
Appears on pages(s):
434-440
Keywords:
alkali-silica reaction; blended cement; fly ash; sulfate attack.
DOI:
10.14359/12820
Date:
9/1/2003
Abstract:
Composite ternary blended cements with chemical activators were optimized by use of Taguchi orthogonal design. The optimized blended cements consisted of 20 to 60% Type I cement, 40 to 80% Class C fly ash and spray-dryer ash (SDA), and 2 to 4% sodium sulfate anhydrite as a chemical activator. The resulting blended cements were evaluated according to ASTM C 1157 and compared with Type I cement. The results show that all optimized blended cements satisfy ASTM C 1157 requirements and have equivalent or higher strength than Type I cement at the age of three days and higher. They are also slightly less vulnerable to sulfate attack and alkali-silica reaction. X-ray diffraction (XRD) and scanning electronic microscopy (SEM) analyses indicate that the addition of sodium sulfate accelerates the formation of ettringite and CSH gel.