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Suggestions for Placing Concrete Slab to Minimize Random Cracking.


What You Do

Why You Do It


Level and compact sub grade, place 4” of damp sand and grade so concrete poured is a consistent depth.

The sand provides a cushion for the concrete, and good drainage.


Separate your new concrete from all existing concrete with ½” felt. Felt must match the depth of your new slab.

The felt separates your new concrete from existing, so it may shrink, expand, and move up (or down) without a detrimental effect.


Screen off our concrete.

Makes sure there are no low spots.


Roller-bug your concrete.

Once over the surface, it helps vibrate, consolidate, and give you a better finish.


Float concrete with wood bull float only.

Wood keeps the surface open and allows the concrete to bleed. This prevents water entrapment, discoloration, and/or plastic cracking.


Cut control joints perpendicular from edge ¼ the depth of the slab, using appropriate spacing. 4” slab would be 8’ x 8’

These joints should allow the concrete to crack in the joint, taking the path of least resistance.


Allow all bleed water to evaporate from the surface; then, you can finish the concrete with metal trowels.

If you do not wait for all bleed water to evaporate, you end-up troweling your bleed water back into the surface, dramatically changing your water:cement ratio, on the surface, causing a weaker surface.


When surface is finished, spray with a concrete cure; if the concrete is colored, you must use a cure formulated for colored concrete.

This protects the concrete from wind and heat, and allows your slab to cure on its own, giving you a much better finished product.


Never add water or dry cement to the surface of your slab.

These two things also change water:cement ration on the surface and can ruin your slab.

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