Title: The Influence of Alkalinity on the Properties of the Accelerated Cement Pastes

Author(s): Zhenping Sun, Chao Chen, Yanliang Ji, Xu Yang, Yuansong Sun, and Lelin Wu

Publication: Symposium Paper

Volume: 330

Issue:

Appears on pages(s): 11-22

Keywords: alkalinity; properties; acceleration mechanism; cement paste; set accelerator; shotcrete

DOI: 10.14359/51711236

Date: 9/26/2018

Abstract:

The objective of this study was to evaluate the influence of alkalinity on the properties and acceleration mechanism of the accelerated cement pastes. Properties of cement pastes relating to its setting time and the strength development as well as its hydration behavior were experimentally tested. XRD and SEM analysis were also performed on the cement pastes to identify the hydration products and their structures.

Results showed that with the increase of alkalinity, the hydration rate and the early compressive strength of cement paste with both alkaline and alkali–free accelerators were accelerated and the setting time was shortened. However, it is harmful for the long-term compressive strength. XRD analysis disclosed the existence of more ettringite with the increase of the alkalinity. However, it appeared no difference between the formation of the ettringite in the cement paste with different alkalinity.