![]() Industry groups specifically warn against using cement-based products in temperatures considered too hot or cold. Plastering in extreme weather conditions can lead to quality and durability problems. But if the plaster becomes too hard before a smooth surface is achieved, continued hard troweling will often result in dark gray discoloration and spotting, especially when calcium chloride is also used.ħ. Well-timed hard troweling can help produce a nice, dense plaster finish. Dark colored plaster is even more susceptible to white spotting and streaking discoloration from too much water troweling.Ħ. ![]() Doing so can weaken the surface and may accelerate deterioration and caused spotting or streaking discoloration. ![]() Still, you never want to work, or force, additional water into the plaster surface when troweling. A little water to lubricate the trowel, however, likely will not harm the plaster surface. Both the ACI and PCA have found that this may increase porosity, shrinkage, and variable (white or light) discoloration. Never add water to plaster surfaces while troweling. The plastering of typical size residential pools shouldn't be completed in less than 4.0 hours.ĥ. Several alternatives to calcium chloride that do not exhibit these characteristics are now available. (Colored plaster, of course, should not contain any calcium chloride as it will lighten the color and become blotchy.) According to the PCA and other testing facilities, too much calcium chloride increases gray mottling discoloration and cement shrinkage. Plaster should contain as little calcium chloride set-accelerant as possible and never more than 2 percent to the amount of white cement. It is recommended that if the plaster has been mixed for more than 90 minutes, the plaster mix should be discarded.Ĥ. A plaster mix should be mixed thoroughly, but also not too long. Higher water/cement ratios, by contrast, cause excess shrinkage and cracking, and fail to offer adequate protection or long-term durability against the effects of water and the environment.ģ. Lower water/cement ratios boost density while reducing permeability, porosity, shrinkage (craze cracking) and water movement within the cement product. Both the American Concrete Institute (ACI) and the Portland Cement Association (PCA) maintain that lower water/cement ratios produce better-quality cement that can withstand occasional exposure to mild acids. When mixing plaster, a thick mix is best. Note: Always select high-quality and appropriate-grade cement and aggregate.Ģ. If it's too lean (more sand), it will be less durable and potentially unworkable. If the plaster is too rich (cement-heavy), it tends to shrink and crack. The best cement/aggregate ratio is about one part cement to 1.5-1.75 parts aggregate (marble sand). Following is a ten-point checklist that will help achieve a lasting and discoloration free plaster.ġ. There are also improper practices that can lead to early deterioration or discoloration. There are proper steps to follow for the making of durable pool plaster.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |