Grouting has been in use for a long time, but it is still regarded as a technique rather than engineering. The study of ground improvement by grouting is rare especially in jointed rock mass. In this study, to examine the grouting effect on the property of rock joint, joint compression test, direct shear test and biaxial compression test were performed on pure rock joint specimens and cement milk grouted joint specimens. After cement milk grouting, the normal deformation characteristics of the joint was linear at the low normal stress level. But as normal stress increased, normal deformation of the grouted joints rapidly increased. The failure envelope of the grouted joints modified to a curve that has cohesion due to grout material hydration with decreased friction angle. The load-deformation curves of the jointed rock masses showed a relatively linear deformation behavior after grouting. Deformation modulus improvement ratio decreased with increasing joint spacing and minimum principal stress.


Mechanical behavior of rock mass is governed mainly by characteristics of rock joints. In many reinforcement methods, grouting has been practiced as a reliable technique to improve the mechanical properties of rock mass by strengthening characteristics of the joint.

Specimen models

The rock types used in the experiments were Hwangdeung granite and Yeosan marble. Specimen dimension of granite joint sample was 10 cm × 10 cm × 15 cm and marble joint sample was 10 cm × 10 cm × 10 cm. Joints were produced artificially by using an apparatus devised to generate tension-joint. The joint roughness characteristics and average roughness amplitude were measured using laser displacement meter and then cement milk grouting were performed on the artificial joint specimen. In this study, it was assumed that grouting were performed by gravitational force and joints was perfectly filled by the cement milk.

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