Title:
Activation of Fly Ash with Dehydrated Cement Paste
Author(s):
Zhonghe Shui, Rui Yu, and Jun Dong
Publication:
Materials Journal
Volume:
108
Issue:
2
Appears on pages(s):
204-208
Keywords:
activation; dehydrated cement paste; fly ash; theoretical Ca/Si ratio
DOI:
10.14359/51682314
Date:
3/1/2011
Abstract:
The activation of industrial by-products is an efficient way to produce binders for concrete in place of portland cement. This paper presents an experimental study on a new cementitious material using fly ash and dehydrated cement paste (DCP). A low-calcium fly ash was activated with DCP that was obtained by heating hardened cement paste at 1202°F (923.15 K). Specimens were prepared with various ratios of fly ash to DCP. All specimens were cured at 68°F (293.15 K) and a relative humidity above 95% for 1 day and were then cured at 203°F (368.15 K) in a steam room for 2a4 hours before testing. The experimental results showed that the strength of the activated fly ash/DCP paste depends on the value of the theoretical Ca/Si ratio (T-Ca/Si) in the mixture. At the optimum level of T-Ca/Si—0.953—a strength of 8.82 ksi (60.8 N/mm2) was obtained. The results of the X-ray diffraction (XRD) analysis and the scanning electron microscope (SEM) image analysis indicated that if the value of the T-Ca/Si is optimal, the fly ash can react completely with the DCP and the microstructure is dense, yielding sufficient mechanical properties for structural use.