Development of a Physical Model and In Situ Test for the Study of Polymer Injections in Concrete Fractures for Waterproofing

Polymer injections in concrete fractures are commonly used in practice for the waterproofing of tunnels. This paper introduces two physical models and in situ test for the study of water and polymer flow in fractures. The physical models were created by pouring on top of each other two concrete slabs separated by a plastic film. The in situ tests were performed in a tunnel concrete fracture sealed with a surface capping. Both fractures were instrumented with multiple ports for injection or pressure measurements. This paper presents the main results for the physical models and some preliminary results of the in situ tests. The parameters that were varied include the injection pressure, injection volume, fluid viscosity, and flow rate. Water and four water-glycerol mixtures were used to verify the influence of viscosity on flow. Three major parameters influenced the results: the boundary condition, the saturation level of the fracture, and the dynamic viscosity of the injected liquid. Sealed fractures and moist fractures provoked an important pressure gain inside the fracture. The highest pressure values were obtained with the most viscous liquid. The propagation of the liquid was influenced by the same three parameters. The in situ tests established the hydraulic aperture and hydraulic conductivity of the joint. This paper is intended for all professionals in the concrete structure reparation field.