Muriatic acid is often used to clean a garage floor or outdoor pavement. Once the acid has done its work, cleaning away oil and grease stains, it needs to be thoroughly cleaned from the concrete or other masonry surface. Any leftover muriatic acid should be neutralized. The neutralization process is a simple task, involving the use of lime or baking soda and water. Use a bucket for mixing the ingredients together, or use the ingredients directly on a spill to neutralize the acid. Get a large bucket, about 5 gallons. Using a larger bucket will minimize splatter issues. Use 3 to 4 cups of garden lime (or baking soda), mixed with 1 gallon of water. Mix the ingredients in the bucket, stirring with a stick. Add in the muriatic acid slowly, being careful not to slosh it over the side of the bucket. Continue stirring and adding more acid and more lime until the chemicals are no longer fizzing. Once all the acid has been neutralized, it can be disposed of safely.