These are the classic reaction resin type used for making two-component injection mortars. For this purpose, unsaturated polyester resins (original resin type) dissolved in styrene as well as styrene-free unsaturated polyester resins are used in which styrene-related monomers function as reactive solvents. These two-component injection mortars can be processed very easily and quickly and typically possess a limited chemical resistance (e.g. in an alkali medium).