The material that constitutes the "concrete blocks" or "blocks" or "rubble", is a semi-cavernous concrete, rather dry appearance. It is a mixture of natural sands and crushed or rolled gravel, cement and water.
It is realized using an automatic control unit guaranteeing a precise and constant dosage of these various constituents. The size and weight of the blocks may vary from one producer to another, but the most common are: - 7.5 x 20 x 50 = 9 kg - 10 x 20 x 50 = 10 kg - 15 x 20 x 50 = 15 kg - 20 x 20 x 50 = 20 kg concrete resistance class B 40.
Composition of concrete blocks
This concrete is made from gravel and natural sands crushed or rolled, cement whose nature, class and dosage depend on expected performance in terms of mechanical strength, and water.
The dosage of cement with respect to dry matter is of the order of 7% for the hollow blocks and about 6% for the solid or perforated blocks.
The dosage of the water varies according to the nature of the sand and the cement dosage (approximately 6% of the total mass).
Block manufacturers are especially vigilant
- the cleanliness of aggregates and especially sand in order to limit the dimensional variations of the finished products and not to affect their resistance;
- the shape of the aggregates to facilitate the filling of the mold and guarantee a concrete of regular appearance;
- the continuity of the granular spindle components (including cement), essential for the regularity of manufacture.
(photos / visuals: © Blocalians, except special mention)
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