Title: Feasibility Study of Using Raman Spectroscopy to Detect Hydration in Wet Pastes

Author(s): by Fengjuan Liu and Zhihui Sun

Publication: Materials Journal

Volume: 110

Issue: 6

Appears on pages(s): 611-618

Keywords: calcium hydroxide; C-S-H; ettringite; portland cement; Raman spectroscopy

DOI: 10.14359/51686328

Date: 11/1/2013

Abstract:
This work focuses on examining the feasibility of using Raman spectroscopy (RS) to study chemical changes in wet cement pastes. To study hydration processes, RS analysis was conducted on both dry portland cement powder and freshly mixed pastes with different water-cement ratios (w/c). The Raman shift peaks in the spectra of the hydrating pastes were traced to look at the appearance of new products and the disappearance or decrease of unhydrated cement ingredients. During the setting period of the pastes, C-S-H gel, calcium hydroxide (CH), and ettringite were able to be identified from the tests. It was also found that the C-S-H gel can be detected earlier in the paste with a lower w/c. For CH, the relatively high intensity was achieved in an hour and it decreased slightly throughout the measuring period in both cement pastes. For both pastes studied, the intensity of the Raman peak representing ettringite stayed constant after detection and then increased dramatically. When the increasing period was surpassed, it decreased continuously until the end of the measuring period.