Investigating the Effects of Cement and Polymer Grouting on the Shear Behavior of Rock Joints

Abstract

This study carried out a comparison between cement grouting and chemical grouting, using epoxy and polyurethane, with respect to their effects on the shear behavior of joints. Joint replicas, with three different grades of surface roughness, were molded and grouted by means of cement and epoxy grouts of various mixtures. To investigate their shear behavior, samples were subjected to direct shear tests under constant normal load (CNL) condition. According to the results obtained, grouting improves the overall shear strength of the rock joints. All the grouted samples yielded higher maximum and residual shear strength in comparison with the non-grouted joint. Grouting resulted in an improvement in the cohesion of all the samples. However, a fall in friction angle by 5.26° in the sample with JRC of nine was observed, yet it was reduced by 2.36° and 3.26° for joints with JRC of 14 and 19, respectively. Cement grouts were found to have a more brittle behavior, whereas the chemical grouts were more ductile. Higher amounts of cement used in the grout mixture do not provide as much cohesion and only increase the brittleness of the grout. As a result of being more brittle, cement grout breaks into small pieces and joint planes are in better contact during shearing; consequently, there would be less of a fall in friction angle as opposed to epoxy grout whose ductile characteristic prevents grout chipping; therefore, joint planes are not in contact and a greater fall in the friction angle occurs. There was no noticeable change in the cohesion of the larger grouted joints. However, the friction angle of both natural and grouted joints increased in the larger joint. This can be related to the distribution of random peaks and valleys on the joint surface, which increases with the joint size.

Study on the Effect of PVAc and Styrene on the Properties and Microstructure of MMA-Based Repair Material for Concrete

“…Grouting is a method that can be used to fill the cracks with appropriate seriflux to achieve the purpose of reinforcement and antiseepage, and it is widely used in the repair works of microcracks [15,16]. Penetration capability is an important evaluation criterion for the success of grouting; especially for those microcracks with a width less than 0.5 mm [17], the grouting performance of cement-based repair materials and organic-inorganic composite repair materials is very limited due to their particle size [18,19], while the organic repair materials with excellent fluidity are the best repair materials for microcracks [20]. Epoxy resin is a typical organic repair material, with high strength, excellent chemical resistance and good adhesive property.…”

Water Consolidation Performance of Acrylic-Polymer-Modified Materials and Their Concrete Impermeability Repair Characteristics

“…Wagner [ 9 ] studied the dynamic rheology of different acrylate grouting materials to determine the setting time and the time to reach maximum strength, but detailed research and analysis on their physical and mechanical properties are still lacking. Abolfazli [ 10 ] studied and analyzed the influence of cement grouting and chemical grouting using epoxy resin and polyurethane on the shear behavior of rock joints, but the impermeability characteristics remained unexplored. In revealing the copolymerization and crosslinking behavior of acrylate grouting materials, Qavi [ 11 ] used SEM imaging to study the crosslinking and copolymerization of acrylamide at different crosslinking agent ratios and reaction temperatures, which provided a reference for controlling the setting time of grouting materials.…”