Investigation of Methods for Removing Stains from Mortar and Concrete

摘要

This investigation consisted of three parts: (a) a literature search to acquire information on the types of stains that can be expected and methods of removal; (b) evaluation of methods of removing stains from mortar specimens; and (c) evaluation of promising stain removal methods on concrete specimens. The literature search indicated that the types of troublesome stains most likely to be found on concrete surfaces are those caused by iron, used lubricating oils, and cutback asphalts. Mortar specimens were made in the laboratory and stained to a mild or severe degree with a solution of iron chloride, lubricating oil, or asphalt. The most effective removal techniques for iron stains were sandblasting, application of an oxalic acid solution, and application of a sodium citrate-sodium hydrosulfite paste. Oil and asphalt stains were not completely removed by any of the methods, but the benzene-CaCO3 paste was the most effective removal method of those used. Concrete specimens were also made, and were severely stained with iron, oil, and asphalt. The most effective removal methods for the iron stains were sandblasting and application of a sodium citrate-sodium hydrosulfite paste; the oil stains were best removed by the sandblasting and the benzene-CaCO3 paste methods. The asphalt stains were not satisfactorily removed by any of the techniques that were tried. (Author)