Limitation of strength of sprayed concrete
September 3-6, 2017
Sprayed concrete is commonly used for large-scale concrete repairs, even repairs of tunnel linings. For concrete repair and strengthening measures with sprayed concrete the stiffness and strength of the reinforcing concrete is aimed to be similar to the old concrete. However, sprayed concrete applied by dry mix shotcrete process exhibits significantly higher strengths due to the process-related lower w/c-ratio. Based upon this fact, the aim of a research study conducted at the Institute for Building Materials of the Ruhr-Universität Bochum was to adapt the properties of the sprayed concrete (e.g. strength, stiffness, bond etc.) to such of a typical old concrete with not too high strength by means of concrete technological and procedural optimization. Simultaneously, the rebound should be kept as low as possible. It proved to be advantageous to substitute cement partly with hydraulic limestone or to use calcitic aggregates instead of quartzitic ones.
Sven Plückelmann, Björn Siebert, and Rolf Breitenbücher, "Limitation of strength of sprayed concrete" in "Shotcrete for Underground Support XIII: New Developments in Rock Engineering, Tunneling, Underground Space and Deep Excavation", Dietmar Mähner, Institute for Underground Construction, FH Münster, Germany Matthias Beisler, ILF Consulting Engineers, Asia (Thailand) Frank Heimbecher, Institute for Underground Construction, FH Münster, Germany Eds, ECI Symposium Series, (2017). http://dc.engconfintl.org/shotcrete_xiii/20