having carefully calculated the amount of cement for our new studio exterior render I was nervous about all the bags that were left over. Needless to say almost pure sand does not stay attached to blockwork for very long. 😦
Cement mortars are rendered on masonry, concrete and other surfaces. The colour of cement, sand, amount of water, mixing, trowel pressure and rendering technique determine the colour of surfaces.
Cement mortars are mixed at two distinctive stages.
1. In dry state mixing of cement is mixed with other ingredients such as lime, chalk, sand, clay, various sizes and shapes of aggregates. Dry mixing requires continuous agitation till water is added, otherwise heavier ingredients settle down. Dry mixing is much easier, requires less energy then any wetted mass. Dry mixing helps penetration of water and thereby reduces the flocculation (wetting of cement particles due to enveloping air). In fast setting or hardening varieties of cements or due to presence of such additives, mixing of wet-mass becomes very difficult due to the resistance.
2. Dry state mixed mass is combined with water. Very intensely mixed mortars are air…
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