The invention relates to glass reinforcement strands, the composition of which comprises the following constituents in the limits defined below, expressed as percentages by weight: 59 to 63% SiO2; 10 to 16% Al2O3; 16 to 23% CaO; 1 to 3.2% MgO; 0 to 2% Na2O+K2O+Li2O; 0 to 1% TiO2; 0.1 to 1.8% B2O3; 0 to 0.5% Li2O; 0 to 0.4% ZnO; 0 to 1% MnO; and 0 to 0.5% F. These strands have improved properties in terms of mechanical strength, acid resistance and high-temperature resistance for a low-cost composition. The invention also relates to a process for producing the said strands and to the composition allowing them to be produced.