3.3. Biological Deterioration

• Microbial Attack: Some bacteria produce acids or sulfides that degrade concrete or steel.

Microbial attack refers to the deterioration caused by certain bacteria. These bacteria can produce harmful byproducts, such as acids or sulfides, that can weaken and degrade building materials like concrete and steel. For example, when bacteria that thrive in moist environments break down organic matter, they produce acids that can react with the concrete, leading to its deterioration over time. This kind of damage can compromise the integrity and strength of the structure.

Imagine a metal tool that gets rusty if left wet in a shed. Similarly, if bacteria grow on concrete or steel in moist conditions, they can ‘eat away’ at the materials, just as the rust eats away at the metal. If the tool is continuously exposed to moisture, the rusting accelerates, much like how concrete can deteriorate under biological attack.

• Algae and Fungal Growth: Can retain moisture and promote physical or chemical damage.

The growth of algae and fungi on structural surfaces can be problematic because these organisms like to grow in moist and shaded areas. They can trap moisture against the material's surface, creating an environment that encourages further degradation. As they grow, they can also produce enzymes that break down the material, leading to both physical and chemical damage. Over time, if left unchecked, this growth can lead to more significant issues like cracks or compromising the structure’s surface.

Think of a damp, shaded corner in your garden where mold and algae thrive on a stone wall. Just like the damp conditions promote growth that can harm the wall, similar moisture retention caused by biological growth on concrete can weaken it over time. If you don't clean that garden corner, the wall might eventually crumble.

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