Bleeding characteristics for viscous cement and cement–bentonite grouts

Bleeding of cement-based grouts reduces the effectiveness of compensation grouting operations. Compensation grouting involves the injection of a grout to heave the soil and compensate for settlements resulting from ground loss during tunnelling with a TBM. A grout bleeds at the incipience of the injection pressure. Water is squeezed out from pores between cement particles, into the ground, in a similar process to water drainage in soil consolidation. Water loss through bleeding has several consequences.

The amount (volume) of bleeding water, expressed via V_b in equation (1), is affected by several parameters.

The development of fractures is dependent...