ABSTRACT
'Precast concrete is of the highest possible quality, both in terms of strength and durability'. When precasting in a modern factory, it is vital to achieve the dual requirements of good workability and early strength. Concrete is often transported automatically from an automatic batching plant to the mould leaving no opportunity for workability tests. Various methods to accelerate the early strength of concrete include rapid hardening Portland cement, chemical accelerators (calcium chloride must not be used) and by external heating, such as steam curing and electrical heating. In precast elements, some of the creep and shrinkage deformations take place prior to installation, something which is not considered in the code equations, and therefore these effects are calculated at the time of installation (typically 7-28 days) and in the long term of 500,000 h.
