Could magnetic properties be used to image a grouted rock volume?

Field validation of a detectable, magnetic, cementitious grout for rock fracture grouting

“…The theoretical and numerical model used in this research is described in Lunn et al (2018), therefore only a summary is presented here. The magnetic field produced by the presence of a body containing magnetite within the ground is governed by Maxwell's magnetostatic equations:…”

“…Field validation of a detectable, magnetic, cementitious grout for rock fracture grouting was selected. The proportion of magnetite to be incorporated into the grout mix was determined based on predictions from the model presented in Lunn et al (2018) which suggested a volume magnetic susceptibility, χ = 0.077 would give a detectability of several metres. From Figure 2 this corresponds to a magnetite content of 15% at f/s =0.7.…”

“…None of these methods are able to definitively determine the location of grout once injected into the ground. Lunn et al (2018) demonstrated that detection of a magnetic grout is theoretically feasible by simulating the magnetic anomaly caused by the presence of a body of magnetically-susceptible material within the Earth's magnetic field. A surface-based survey of shallow buried magnetic grout objects with a commercial magnetometer showed that the magnetic grout is detectable and good agreement was obtained between the measured and modelled magnetic anomaly.…”