Physical Effect Of Simulated Acid Rain Bath On Concrete

     Concrete is the most common construction material used from road and bridges all the way to skyscrapers. Acid rain is a phenomenon of acid building in the atmosphere and precipitates into rain. Concrete and acid rain react chemically destroying the Calcium Carbonate (caco3). Calcium Carbonate forms the structural component of concrete.

     This study aims to determine the physical effects of acid rain on concrete, mainly, the changes in weight, color, texture and compressive strength. The study is designed to use Prohesion Test to accelerate corrosion on 150 mm x 300 mm concrete cylinder blocks cured for 28 days. Prohesion is a wet-dry cycle of exposure using laboratory controlled chemicals. Sulfuric acid (H2SO4) and Nitric Acid (HNO3), acids that form acid rain, is diluted in solutions of ph 2.0, ph 3.0, and ph 4.0. A solution of ph 5.6, the rain's natural acidity, is used as control solution. The blocks are tested for their compressive strength. The result is evaluated using Student's t-test.

     The blocks showed consistent weight reduction with respect to their acid exposure. Ph 2.0 blocks lost an average of 142 grams, ph 3.0 by 107 grams, ph 4.0 by 49 grams, and the ph 5.6 by 43 grams. The loss of weight of the control specimen indicates that the cylinder blocks were still undergo curing even after the 28-day curing period. Blocks exposed to ph 2.0 and ph 3.0 showed changes in color and texture. It produced white dust patina around the blocks that resulted from corrosion of the concrete surface. The ph 2.0 and ph 3.0 blocks exposed an occasional to consistent amount of fine aggregates in the surface. The result of the t-test showed that corrosives have no significant effect on the compressive strength of concrete.