with a particularly preferred modification the inventive two component mortar compositions contain in total or mixed for curing 20 to 24 and especially 21 to 21 5 weight percent of unsaturated polyester 12 to 20 and especially 14 to 17 weight percent of reactive diluent 46 to 59 and especially 52 57 weight percent of filler 1 to 3 and especially 1 0 to 2 5 weight percent of a thixotropic agent and especially from 2 5 to 4 5 weight percent of a free radical curing catalyst the percentage in each case being based on the total composition the inventive hardenable mortar compositions are used especially as mortar compositions for securing tie bars in boreholes in solid material such as concrete masonry rock and the like that is as essentially homogeneous hard materials in this connection it has proven to be particularly successful to use mortar compositions the particle size of whose quartz filler falls within the lower range for smaller tie bars while mortar compositions the particle size of whose quartz filler falls within the upper range are used for larger tie bars particle size ranges from about 0 1 to 0 25 mm have proven to be particularly successful for securing m 6 m 16 tie bars with a maximum annular gap of 1 mm while particle size ranges from about 0 4 to 0 6 mm have proven to be particularly successful for securing larger tie bars with annular gaps from about 1 to 2 mm the following examples illustrate a two component mortar composition in accordance with the present invention ______________________________________unsaturated polyester resin 32 0 70 solution in styrene benzoyl peroxide 2 0 50 solution.