Consistency (concrete)
| Consistency ranges of the fresh concrete according to DIN 1045-2 | ||||
|---|---|---|---|---|
| Consistency area | Slump classes | Compaction dimension classes | ||
| class | Slump [mm] | class | Degree of compaction | |
| very stiff | - | - | C0 | = 1.46 |
| stiff | F1 | ≤ 340 | C1 | 1.45 to 1.26 |
| plastic | F2 | 350 to 410 | C2 | 1.25 to 1.11 |
| soft | F3 | 420 to 480 | C3 | 1.10 to 1.04 |
| very soft | F4 | 490 to 550 | - | - |
| flowable | F5 | 560 to 620 | - | - |
| very flowable | F6 | 630 to 700 | - | - |
| SVB | - | > 700 | - | - |
In concrete and structural engineering, consistency is the measure of the recipe- dependent stiffness and workability of the fresh concrete , i.e. the not yet hardened concrete.
Standardization in Europe and Germany
The German standard DIN 1045, like the European standard EN 206, defines seven consistency ranges for fresh concrete: very stiff , stiff , plastic , soft , very soft , flowable and very flowable . The areas are described by the slump classes F1 (stiff) to F6 (very fluid) and by the compression classes C0 (very stiff) to C3 (soft).
In earlier editions of DIN 1045, which are no longer valid, four or even earlier (1978) three consistency ranges were defined: stiff (KS, K1), plastic (KP, K2), soft (KR, "rule consistency", K3) and flowable (KF). In these old standards, concrete with a soft consistency was highlighted and referred to as concrete with regular consistency (KR). Such a concrete is a soft concrete that is easy to convey, process, install and compact.
Investigation and testing
To determine the consistency of fresh concrete, there are standardized, construction site-specific methods: the compaction test for the degree of compaction and the spread test for the slump. In addition, the can slump and setting time are measured to infer the consistency.
The testing of the properties of fresh and hardened concrete is standardized across Europe in the EN 12350 standard. In Germany, the adopted version of DIN EN 12350 applies.