Concrete Production - Specification

A composite with many variables, represented by numerous gradings which indicate components, quality and manufacturing control.

Grade mixes: C7.5, C10, C15, C20, C25, C30, C35, C40, C45, C50, C55, and C60; F3, F4 and F5; IT2, IT2.5, and IT3.

1. Standard Mix - BS guidelines provide this for minor works or in situations limited by available material and manufacturing data. Volume or weight batching is appropriate, but no grade over C30 is recognised.

2. Prescribed Mix - components are predetermined (to a recipe) to ensure strength requirements. Variations exist to allow the purchaser to specify particular aggregates, admixtures and colours. All grades permitted.

3. Designed Mix - concrete is specified to an expected performance. Criteria can include characteristic strength, durability and workability, to which a concrete manufacturer will design and supply an appropriate mix. All grades permitted.

4. Designated Mix - selected for specific applications. General (GEN) graded 0-4, 7.5-25 N/mm2 for foundations, floors and external works. Foundations (FND) graded 2, 3, 4A and 4B, 35 N/mm2 mainly for sulphate resisting foundations.

Paving (PAV) graded 1 or 2, 35 or 45 N/mm for roads and drives.

Reinforced (RC) graded 30, 35, 40, 45 and 50 N/mm2 mainly for prestressing.

See also BS EN 206-1: Concrete. Specification, performance, production and conformity, and BS's 8500-1 and -2: Concrete.