New walks are to be placed in the yard of our high school. These walks must be rough enough not to be slippery. At the same time some existing walks in the yard and along the streets surrounding the school are to be renovated to get rid of the polished, slippery surfaces they now have. How is this done?
On new concrete you can obtain any degree of roughness desired by use of brooming. Brooming is done by drawing a broom over the surface after the finishing operations of floating or troweling. The depth of groove depends on the texture of the broom and when in the finishing operations the broming is done. Troweling can be omitted and brooming done after floating if a very coarse texture is wanted. Old concrete surfaces may be roughened in two ways: by use of a scarifying machine or by acid etching. Acid etching is done by applying muriatic acid uniformly over the surface and flushing it off promptly and thoroughly when it stops bubbling. The acid should preferably be diluted with as little as one or as many as five parts of water before using. The treatment is continued until the degree of etch desired has been achieved. Workers should wear rubber gloves, rubber boots and goggles and should avoid breathing the fumes. If acid gets on any part of the skin it should be immediately washed thoroughly with running water.