Effects of Foaming and Drainage Behavior on Structure and Properties of Polyurethane/Water Glass (PU/WG) Grouting Materials for Coal Mines

Figure 9

SEM images of the C14 samples: (a) C14-1%, (b) C14-0.75%, (c) C14-0.5%, and (d) C14-0.25%.

(a)

(b)

(c)

(d)