What are the effects of efflorescence on concrete porosity?

Efflorescence, the white crystalline deposit often seen on concrete surfaces, significantly affects concrete porosity and long-term durability. This phenomenon occurs when water-soluble salts within the concrete migrate to the surface through capillary action, leaving behind salt crystals as the water evaporates.

The primary effect of efflorescence on concrete porosity is the gradual increase in pore structure. As salt crystals form and expand within the microscopic pores, they create additional voids and micro-cracks. This process accelerates when exposed to freeze-thaw cycles, where the expanding crystals exert pressure on the surrounding concrete matrix.

Research indicates that efflorescence can increase concrete porosity by 15-30% in severe cases, directly impacting compressive strength and permeability. The salt deposits also attract moisture, creating a cycle of deterioration that compromises the material's integrity.

Preventive measures include using low-alkali cement, proper curing techniques, and applying hydrophobic sealants. Understanding these effects helps engineers design more durable concrete structures resistant to environmental degradation.

The long-term implications of efflorescence extend beyond aesthetics, potentially reducing the service life of concrete structures by decades if left unaddressed. Regular inspection and maintenance remain crucial for infrastructure longevity.