The process of laying pavement quality concrete involves the compaction of a very specific concrete design at a consistence level that allows the form to move continuously. It is essential that the concrete is able to support itself in the shape moulded and hence concrete for pavement quality applications tends to be of very low consistence (slump) level.
Pavement quality concrete requires a greater degree of accuracy, both in the batching process and in ensuring that the consistence level is suitable for the paving process whether by hand or by slip forming.
The supply of concrete to a pavement quality contract is critical, when production begins on a particular day the supply of concrete should be maintained at the rate specified to ensure the feed to the slip forming machine is maintained.
Once an order is received for a slip forming contract it is essential that the supplier allocates sufficient truck resources to maintain the supply rate specified, the supply of concrete should also not be interrupted with too many supplies to other customers. It is likely that interrupted supply rates to the slipforming process may hinder the production process as well as give potential for quality issues on the final pavement.
The main issues with batching pavement quality concrete are:-
A record shall be maintained of all batch weights when producing slipform concrete, where plants are not using a manual batch record or data is not captured automatically, the unrecorded information should be documented.