Diluting concrete with water to make it workable

[DanielP]

At a concrete seminar that I attended years ago, we were urged to use very little vibrating, as this tended to move the large aggregate down lower into the slab, thus creating weakness. Plasticizers may be ordered in the mix to make it more workable without adding water. Also, highly emphasized, was to let the bleed water escape (evaporate and percolate downward*) before floating and finishing. and never add water, after the slab is placed, except as a fine mist, to slow excessive evaporation. Do not trowel water down into the finish burn.

* If plastic sheeting is used under the slab, it should be used under a layer of compacted base course, to allow the bleed water to escape uniformly by evaporation and percolation.

When vibrating, use quick stabs and move along, so as not to allow the large aggregate to liquify and sink to the bottom.