INFRASET - Pre-Stressed Concrete Sleepers for Main Lines and Sidings

INFRASET, part of the global Grinaker-LTA group, has been a leading manufacturer of railway sleepers since 1928. 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 for rail crossings. INFRASET has licence agreements with Walter Bau (Germany) and Abetong (Sweden).

MONOBLOCK PRE-STRESSED CONCRETE SLEEPERS

Pre-stressed monoblock sleepers have been in use around the world for more than 50 years, and have proved to be the preferred sleeper in Southern Africa since the late 1950s. With close ties to Abetong Teknik, INFRASET have been able to be at the forefront of sleeper development.

Monoblock sleepers maintain in their geometry regardless of the conditions it is placed in - ensuring a constant rail gauge and rail seat inclinations. The weight of the sleeper, combined with its end face design and large solid area, ensures a large contact area with the ballast that provides excellent track stability while reducing ballast pressure.

HIGH STRENGTH PRE-STRESSED CONCRETE

The use of high strength concrete ensures that the sleepers are resistant to the aggressive conditions it will be exposed to during its lifetime. By using a pre-tensioned design, any small cracks that could form as a result of accidental damage will automatically close, preventing degradation of the reinforcing and damage to the integrity of the sleeper. Concrete also provides an excellent electrical resistance required to ensure reliable and safe track circuiting.

SABS ACCREDITED QUALITY CONTROL

All INFRASET concrete sleeper-producing factories are SABS ISO accredited.

Concrete sleepers are produced to strictly laid down procedures so that the company and the customer are assured of a quality product.

All raw materials received, except cement, is sampled and tested to written sampling plans and procedures. Cement supplied is produced to SABS ENV 197: 1992 Cem 1 52.5Mpa. The cement supplier provided INFRASET with auto control records and sodium equivalent records.

During the process concrete strength, concrete consistency, stressing of wire, production process and the release of pre-stress are all controlled as per written procedures.

RAIL SEAT AND SLEEPER EQUIPMENT TESTING

The critical concrete railway sleeper dimensions are checked as per a sampling plan. The critical dimensions checked are as follows: rail seat cant, twist, cast in component (too high or too low), rail seat flatness, overall length (distance between outside shoulders) and rail seats.

One concrete rail sleeper out of every 600 concrete sleepers produced will be randomly selected and tested to crack (as per the design moments). One sleeper out of every line of concrete sleepers produced will be tested to the minimum load.

The sleeper tests are carried out on rail seat, centre negative and centre positive.

All equipment used to measure or test is checked or calibrated at given periods as indicated on the measuring and testing equipment register. The checks and calibrations are traceable to an accredited calibration agency.

SLEEPER STACKING AND HANDLING

The size and weight of concrete sleepers necessitate careful handling and stacking to ensure safety and optimal life span. Factory stacking areas are specially designed on a flat stable area with correctly spaced plinths to prevent damage of products before dispatch. A correctly sized stacking timer, that prevents direct contact between two sleepers and provides adequate space between the layers for access by loading equipment, is placed between the sleepers to prevent damage. The stacking height should be limited to a maximum of 20 sleepers.

Sleepers can either be handled separately or by approved multiple sleeper handling equipment.

WAGON LOADING AND TRANSPORT

Two of INFRASET's factories have private sidings, making it ideal for loading wagons as well as road transport. These factories are equipped with high capacity overhead cranes and multiple sleeper handling equipment to ensure high loading rates. Loading is carried out by qualified staff and dunnage is provided should customers require to stack the sleepers before installation.