The standard outlines specific requirements for making specimens, including:
The water temperature must be maintained at 20°C ± 2°C.
The standard requires specimens to be cast in at least two layers, though the exact number depends on the specimen size and the compaction method used. Step 1: Placing the Concrete Fill the mold in equal layers. For a standard cube, two layers are typically sufficient. bs en 12390-2:2019
The standard mandates that moulds must be rigid, non-absorbent, and capable of retaining their shape. It provides precise dimensional tolerances (e.g., for 150 mm cubes, the tolerance is typically ±0.2 mm) and specifies that the internal surfaces must be smooth and free from defects. A significant emphasis is placed on the verification of mould dimensions, recognizing that worn or warped moulds produce non-standard specimens that yield inaccurate strengths.
By standardising these environmental and physical variables, this document eliminates testing disparities. It ensures that when a cube, cylinder, or prism is crushed, the data reflects the true potential of the concrete mix rather than errors introduced by poor laboratory techniques. 1. Scope, Significance, and Equipment Requirements For a standard cube, two layers are typically sufficient
According to , the preparation of specimens must be rigorous to avoid premature failure or skewed results. 1.1 Moulds
Ensure the molds are clean, properly assembled, and thinly coated with a release agent. No excess oil should pool at the bottom of the mold. 3. Molding the Test Specimens A significant emphasis is placed on the verification
Compaction must continue until no further large air bubbles emerge on the surface, and the surface becomes relatively smooth with a glint of cement paste. BS EN 12390-2 permits three primary compaction methods: