This part of EN 13230 defines technical criteria and control procedures which have to be satisfied by the constituent materials and the finished concrete sleepers and bearers, i.e.: precast concrete sleepers, bearers for switches and crossings, and special elements for railway tracks. The main requirement of concrete sleepers and bearers is the transmission of vertical lateral and longitudinal loads from the rails to the ballast or other support. In use they are also exposed to moisture, which can result in detrimental chemical reactions within the sleeper and to frost damage. In this standard mechanical tests are defined which provide assurance of the capability of sleepers or bearers to resist repetitive loading and provide sufficient durability. In addition controls are placed on the manufacturing process and tests set out which will ensure that the concrete will not suffer degradation in service through chemical reaction and frost damage.