Pre-Stressed Concrete Sleepers for Main Lines and Sidings
INFRASET, a business unit of AVENG (Africa), has been a leading manufacturer of railway sleepers since 1958. INFRASET produces a wide range of pre-stressed concrete sleepers for main lines and sidings, ranging from 18.5t to 30t axle loads. Specialised products include sleepers for turnouts, tunnels, stacker reclaimers and level-crossing slabs.
INFRASET has licence agreements with Abetong Teknik (Sweden), Walter Bau (Germany) and Sonneville International Corporation (US), and has the technical capacity to design and manufacture equipment to establish sleeper factories internationally. Infraset has been involved in the setting up of sleeper factories in countries such as Malawi, Australia, Brazil, Indonesia, Sri Lanka, Namibia, Zambia, Botswana, Zimbabwe and Argentina.
Concrete sleepers, the preferred choice both locally and internationally, have been used in South Africa for more than 50 years. With close ties to Abetong Teknik, INFRASET has been at the forefront of sleeper development.
Concrete sleepers maintain their geometry regardless of the conditions in which they are placed – ensuring constant rail gauge and rail seat inclinations. Their weight, end-face design and large soffit area ensure maximum ballast contact, reduced ballast pressure and excellent track stability.
High strength pre-stressed concrete
The use of prestressed 60MPa concrete ensures that sleepers are able to withstand variable loading conditions. Moreover, small cracks which can appear through accidental damage close automatically, preventing the degradation of the reinforcing steel and any damage to the integrity of the sleepers.
SABS-accredited quality control
All INFRASET concrete sleeper-producing factories are SABS ISO accredited.
Concrete sleepers are produced to strict production procedures, which ensure a quality product capable of many years’ service.
All raw materials are sampled and tested according to sampling plans and procedures, and cement supplies are accompanied with detailed test reports from the supplier.
Pre-tensioning of the wire reinforcement, concrete consistency and workability, the positioning of cast-in components and reinforcement are all closely controlled during the manufacturing process. Close attention to and monitoring of the heat curing process ensures adequate concrete strength for pre-stress transfer.
Rail seat and sleeper equipment testing
The critical concrete railway sleeper dimensions are checked according to a sampling plan. The critical dimensions checked include rail-seat cant, rail-seat relative twist, cast-in component height, rail-seat flatness, overall distance between outer shoulders and rail seats, and wire reinforcement positions.
One sleeper out of every 600 produced is randomly selected and then tested to ultimate loading. The crack load must be greater than the design crack load for the batch to be accepted. One sleeper from each production line is also tested daily to ensure that the minimum design criteria are met. These tests are carried out for rail-seat positive moments as well as for centre negative and positive moments.
All equipment used to measure or test is checked or calibrated at given periods in compliance with the measuring and testing equipment register. These checks and calibrations are traceable to an accredited calibration agency.
The high-strength-to-weight ratio of prestressed concrete electrification masts sets them apart from poles made of other materials. Fully prestressed masts are produced using 60MPa concrete.
The rectangular taper of INFRASET’s concrete masts and an I-section design results in an aesthetically pleasing light grey pole. Concrete masts are corrosion resistant and enjoy an internationally proven reputation for maintenance-free performance.
Pre-stressed concrete masts are manufactured with guaranteed design strengths which comply with client specifications.