Portland self levelling cement is a type of pourable cement that is primarily used in the preparation of interior floors as an underlayment to support new floor covering installations. As the name implies, it "self-levels' because of it's relatively thin consistence. This unique quality in a cement product enables it to be laid in a very thin layer - from 1/8 inch to over 2 inches without losing any of it's compressive strength or elasticity. This product requires very little curing time (between 12 and 18 hours) which means that the final flooring covering can usually be installed the very next day. It's easy to use, and an excellent way to fix cracked, uneven or out-of-level floors with minimal effort.
Prepare the substrate, which is the material upon which the Portland cement will be laid upon. Remove loose stones or rocks, and clean up as much dirt as possible with a shop vac. Exterior grade plywood and cement backerboard substrates should be firmly attached to the existing floor using additional deck screws if necessary. Ceramic tile, slate, marble, and terrazo substrates should all be firmly attached prior to installing the Portland cement. Materials such as adhesive, glues and caulks and other flexible materials should be removed if possible, since they are not acceptable substrate materials.
Put on eye protection. Add approximately six quarts of cool clean water to a large cement mixing pan. Add one bag (22.7 Kilogram) of Portland self levelling cement to the water slowly. Mix slowly by hand using a masons trowel until it becomes a pourable "syrup like" fluid - similar to pancake batter. If large quanities are desired, use a slow speed bucket mixer, but do not use any high speed devices. .
Ration the entire mixing process, so that you do not mix more self leveller than you can use within ten minutes. Increase or decrease the quantities mixed as needed. Do not over mix, since the self levelling compound will begin to set immediately after it contacts water.
Pour the Portland cement self leveller mix onto the floor, applying more quantity of the mix to low areas and less to high areas. After the entire batch of mix has been applied, use a cement squeegee with the adjustable height pins set to your desired depth to spread the material. Remember you only have approximately 10 minutes after mixing to complete your application. Smooth the surface using the squeegee.
Allow the mix to cure for at least 5 hours before you walk on it. Allow 18 hours before applying any additional stress, such as nailing or sliding heavy objects across it.
Never use Portland self levelling cement over a substrate consisting of hardwood flooring, chipboard, siding, presswood composites, asbestos impregnated board, lauan or other malleable plywood, metal, or any glass, plastic or other similarly flexible substrates.