Experimental study of the spontaneous imbibition characteristics of mudstone extracting water from cement grout

Abstract

This study presents the imbibition characteristics of mudstone extracting water from cement grout. The pore-size distribution characteristics of the weak-cemented mudstone were obtained by some pore characteristic tests. The water distribution and migration of mudstone during imbibition with cement grout of different water-cement (W-C) ratios were tested by nuclear magnetic resonance (NMR), and surface deformation and water (from the cement grout) migration velocity (migration state) for mudstone samples with different initial water content were tested by digital photographic measurement (DPM) tests. The results showed that each T2 spectrum presented an isolated bimodal feature, and the left peak area was much larger than that of the right, indicating that the mudstone is mostly microporous, which confirms the pore characteristics of the mudstone obtained by scanning electron microscope, mercury intrusion porosimetry, and nitrogen adsorption desorption. The average slopes of the curves (signal amplitude and total area of the peak) increased with the increasing W-C ratios of grout, but the W-C ratio of 1 was a critical value for the imbibition capacity of mudstone extracting water from the cement grout. The deformation ranges of mudstone samples were very consistent with the ranges of spontaneous imbibition, and the deformation of the mudstone samples increased with the increasing imbibition time; the values of grout viscosities after the imbibition were all bigger than those of original cement grout. Moreover, the water migration velocities showed a trend of increasing and decreasing with the increase of W-C ratios of grout and the initial water content of mudstone samples at the same imbibition time.