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

Table 2

Average value and standard deviation of compressive strength of the sample.

Sample	Compressive strength (MPa)			Average value (MPa)	Standard deviation
C7-1%	42.6	43.2	44.0	43.3	0.5735
C14-1%	2.3	2.8	3.0	2.7	0.2944
C17-1%	5.5	5.0	4.2	4.9	0.5354