Study of decorative acid staining on concrete floor /

Abstract

Flooring in any building has substantial aesthetic effects on the interior. Flooring techniques frequently being used in Asia and especially Pakistan are rigid in nature. Typically used flooring types are marble flooring, ceramic tiles, mosaic flooring, wooden flooring, PVC sheet, vinyl sheeting, etc. All of these floors, once installed cannot be redesigned without destructing the previous material and installing a newer one. Many other problems are associated with different flooring types. For example ceramic tile designs trend diverges within very short time, and one cannot find the same design in order to conserve partially damaged floor or to install same design in an adjacent place. On the other hand, acid staining can be done multiple times on the same concrete surface without any destruction and comparatively is low cost. This research introduced the usage of concrete as a decorative finish by applying acid staining. Acid stains are solutions of diluted acids with inorganic salts. Acid stain is applied to the set/hardened plain cement concrete floor surface. Application of acid stain corrodes the concrete surface a bit and the salt present in acid stain reacts chemically with hydroxide of cement to form new compounds of different colours. Acid stains can be applied multiple times to redesign and recolour the surface at a low cost compared to other flooring techniques. Acid stain takes almost 6-8 hours to stain the surface. It is then neutralized with ammonia/some other alkaline solution to stop the corrosion effect of acid. After washing, sealer is applied to the dry surface of stained floor to impart some glory look and seal the colour for longer time. Departmental laboratory floor and concrete samples are used in experimentation. Sulfuric acid and hydrochloric acids along different salts,e.g. Ferric Chloride, Ferric Sulphate, Copper Chloride, Copper Sulphate are used in the study and formulations of acid stains to achieve decorative concrete by their application, are devised. As a result, some tones of brown and green colours are achieved. Effect of acid stain’s application on the compressive strength of the concrete floor is also tested to ensure its applicability. It is found that up to 11% strength reduction is caused to floors due to usage of acid staining for decorative purpose. Concrete cubes of 150mm size are tested according to British standard BS:1881.This reduction is not the hindrance in the usage of acid staining on concrete in ordinary household floorings.