Hydration process of fly ash blended cement pastes by impedance measurement.pdf

Construction and Building Materials 113 (2016) 939–950Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier .com/locate /conbui ldmatHydration process of fly ash blended cement pastes by impedance measurement/10.1016/j.conbuildmat.2016.03.141 0950-0618/
2016 Elsevier Ltd. All rights reserved. ? Corresponding author. E-mail address: victorymother@163.com (E. Chen).S.W. Tang a,b, X.H. Cai a, Z. He a, H.Y. Shao b, Z.J. Li b, E. Chen b,? a State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan, China bDepartment of Civil and Environment Engineering, The Hong Kong University of Science and Technology, Kowloon, Clear Water Bay, Hong Kong h i g h l i g h t s
Hydration of high-dosage fly ash blended cement pastes is evaluated.
Four hydration stages are identified.
Gismondine is found in the zeolite formation stage.a r t i c l e i n f o Article history: Received 18 December 2015 Received in revised form 12 March 2016 Accepted 23 March 2016 Keywords: Cement paste Fly ash Zeolites Hydration Pore Impedancea b s t r a c t This study focuses on the early-age hydration development in fly ash blended cement pastes. The char- acteristic features in different hydration stages and the evolution of zeolites phase, viz., gismondine, are identified in high-dosage fly ash blended cement-based materials using the innovative non-contact impe- dance measurement (NCIM), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravi- metric analysis (TGA), heat evolution test and pore solution analysis. It is found that the zeolite formation stage is comparatively distinct at the late hydration period. Besides, the influence of fly ash dosages in cement pastes on setting time and compressive strength are further examined.
2016 Elsevier Ltd. All rights reserved.1. Introduction The current global production of fly ash is reported as around800 millionmetric tons per year [1]. The