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Preparation and Performance of a Fluorine-Free and Alkali-Free Liquid Accelerator for Shotcrete

Jianbing Zhang1, Rongjin Liu1,2,3,*, Siyuan Fu1, Tianyu Gao1, Zhongfei Zhang1

1 College of Material Science and Engineering, Guilin University of Technology, Guilin, 541004, China
2 Guangxi Engineering and Technology Center for Utilization of Industrial Waste Residue in Building Materials, Guilin, 541004, China
3 Guangxi Beibu Gulf Engineering Research Center for Green Marine Materials, Guilin, 541004, China

* Corresponding Author: Rongjin Liu. Email:

Journal of Renewable Materials 2021, 9(11), 2001-2013.


Based on aluminum sulfate, a fluorine-free and alkali-free liquid accelerator (FF-AF-A) was prepared in this study. The setting time and compressive strength of three cement types with different FF-AF-A dosages were fully investigated. The compatibility of the FF-AF-A with the superplasticizers were also investigated, and the early hydration behavior and morphology of the hydration products of reference cement paste with the FF-AF-A were explored by hydration heat, X-ray diffractometry (XRD), and scanning electron microscopy (SEM). Test results indicated that adding the FF-AF-A at 8 wt% of the cement weight resulted in 2 min 35 s initial setting time and 6 min 30 s final setting time. The 1-day compressive strength of the cement mortar with 8 wt% of FF-AF-A reached 13.5 MPa, which represents an increase of 35% as compared to the strength of cement mortar without the FF-AF-A, and the 28-day compressive strength ratio was 119%. In addition, the FF-AF-A also showed good compatibility with different superplasticizer dosages. The results show that, when the FF-AF-A was added to the cement paste, it promoted the formation of ettringite crystals due to the aluminum ions (Al3+) and sulfate ions (SO4 2-) reacted with gypsum in the cement, as well as promoted the hydration of tricalcium aluminate (C3A) and tricalcium silicate (C3S) leading to the overall structure becomes more compact. As a consequence, the hydration heat rate of the cement sharply increased, the cement paste setting time is shortened, and the compressive strength of cement mortar is improved.


Cite This Article

Zhang, J., Liu, R., Fu, S., Gao, T., Zhang, Z. (2021). Preparation and Performance of a Fluorine-Free and Alkali-Free Liquid Accelerator for Shotcrete. Journal of Renewable Materials, 9(11), 2001–2013.


This work is licensed under a Creative Commons Attribution 4.0 International License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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