The Variances Between Concrete and Screed
Basically, screed and concrete are created from the same basic ingredients: water, aggregates, and cement. However, the variances between the two substances are distinguished by the size of the aggregate used, the grade of cement, the consistency of the mix, and the intended use or application.
How Concrete Is Made
Concrete in its most basic form is a rock-like mass created from the hardening of aggregates and cement paste. This mix is comprised of cement, sand, coarse-type aggregates, and ballast or gravel. Several variations of concrete can be made to fit different strength requirements and uses.
How Screed Is Made and Used
Alternatively, the screed is a thin layer of cement paste mixed with fine aggregates and sand. This mixture is applied to a concrete floor base or used as a flat and smooth leveling surface. Therefore, the screed is used to support a final floor finish. Screeds are mixed with one part cement and three to five parts sand. Zero to 4mm washed and sharp sand is used for leveling screeds.
In the case of heavy-duty screeds, Billericay concrete and mortar ready mixed applications use 25% of the aforementioned 0-4mm sand and 6-10mm single-sized aggregates, creating a mix proportion of 1:3:1 of cement, sand, and single-sized aggregates. This mix is created to facilitate trowelling as well as to enhance the density of the screen.
Concrete is used in a variety of venues as a building material, as a wearing surface, and for masonry. In addition, concrete can be given a range of finishes all the way from coarse to exceptionally smooth, depending on its intended use.
In contrast, the screed is generally used to produce a level and smooth surface for a final finish. Therefore, the screed is not intended to be used as a final wearing surface. However, the material is expected to supply adequate strength and support to withstand the impact of continual traffic.