Experimental Study on Groutability of Low Calcium Fly Ash-Cement Slurry

Abstract

Abstract: In order to explore the application of low calcium fly ash in the grouting method, based on the engineering background of strengthening low strength broken roof, the corresponding laboratory tests were carried out. The variation law of bleeding rate, concretion rate, viscosity, setting time, and grouting stone body strength of slurry were investigated under the influence of different water-solid ratios and fly ash content. The microstructure of the grouting body was analyzed by the scanning electron microscope (SEM) and the X-ray diffraction (XRD). The results show that when the water-solid ratio of the slurry is 0.7:1 (mass ratio) and fly ash content is 70% (mass fraction), the performance parameters of the slurry are optimal. At this time, the viscosity of the slurry is 55.50 s, the bleeding rate is 3.89% (volume fraction), and the concretion rate is 94.16% (volume fraction). The compressive strength of the slurry stone at three curing age stages of 3 d, 7 d, and 28 d are 0.67 MPa, 1.77 MPa, and 3.10 MPa, respectively. XRD qualitative phase analysis shows that the addition of alkaline activator increases the diffraction peak of Ca(OH)₂ in the system. And with the increase of curing age, the diffraction peak of Ca(OH)₂, quartz, and mullite phase decrease significantly, which promote the release of the potential activity of fly ash. SEM microstructure and morphology analysis reveal that the microstructure of slurry is loose in the early stage, with thin-plate crystal Ca(OH)₂ and a small amount of acicular AFt (ettringite). At the later stage, the thin-plate crystal Ca(OH)₂ and the flocculated C-S-H gel intertwine together to form a dense network structure.

Key words: fly ash-cement slurry, grouting material, groutability, hydration product, micro mechanism

CLC Number:

TQ502

ZHOU Shengquan, CHEN Wei, LI Jianwei, LI Dongwei. Experimental Study on Groutability of Low Calcium Fly Ash-Cement Slurry[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2021, 40(5): 1554-1563.

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