Experimental Study on Performances of Cement-Fly Ash Composite Expansive Stable Grout

Abstract

The cement-fly ash composite expansive stable grout was prepared to deal with the problems of poor stability and volume shrinkage of ordinary cement grout, and the effects of fly ash ratio and water-binder ratio on the properties of the grout and its consolidation were analyzed. In addition, the mineral composition and microstructural characteristics of grout consolidation with different mixing ratios were investigated. The experimental results indicate that fly ash and the increase of water-binder ratio reduce the strength of the grout consolidation, and increase the fluidity, bleeding rate, and setting time of the composite grout. However, the magnitude of the fly ash-induced strength reduction decreases with time. And the effect of fly ash on the setting time and compressive strength becomes more significant with the water-binder ratio. The later expansion performance of grout consolidation (after 7–42 d) is improved by fly ash. But the expansibility of consolidation with fly ash decreases at the early curing stage, and the reduction amplitude of expansion rate is smaller and the reduction age is shorter with the water-binder ratio increase. Fly ash improves the corrosion resistance performance of grout consolidation, and the corrosion resistance coefficient rises first and then falls with the fly ash ratio. And for 0.6:1 water-binder ratio, the corrosion resistance coefficient of the samples mixed with fly ash are greater than 100%. XRD and SEM show that fly ash inhibited the formation of ettringite in the early stage, which is unfavorable to the expansion of the slurry, and with the increase of age, this effect gradually weakened.

Keywords

cement-fly ash composite grout / grout property / expansibility / hydration product / micromorphology

RIGHTS & PERMISSIONS

Wuhan University of Technology and Springer-Verlag GmbH Germany, Part of Springer Nature