Acid deposition and infrastructure

• A. It strengthens concrete
• B. It reduces acidity
• C. It has no effect on buildings
• D. It damages man-made structures due to acidification and corrosion

Answer: (D)

Acid deposition lowers the pH of rain and moisture on surfaces, introducing acids like sulfuric and nitric acid that chemically attack building materials. In concrete, the acidic environment neutralizes the alkaline cement paste, increasing porosity and weakening the matrix, and it can compromise the protective film around any embedded steel, allowing rust and internal cracking to develop. In carbonate stones such as limestone or marble, acids dissolve calcium carbonate, leading to surface etching and material loss. Over time, this combination of chemical attack and corrosion weakens and damages structures made from these materials, which is why acid deposition is associated with infrastructure deterioration.

The other ideas don’t fit because acid deposition does not strengthen concrete, it does not reduce acidity, and it certainly does have effects on buildings.