How do you spot efflorescence?

January 11, 2019 /

Efflorescences are crystalline deposits of salts that occur when soluble salts and other water dispersible materials come to the surface of concrete, mortars and other building surfaces. It appears as a white or greyish powdery substance on floors and walls.

Low temperatures and moist conditions induce efflorescence. Error in building surface installations such as joint material failure and improper ground storage may also cause efflorescence.

The cause of efflorescence may be slightly different on various building materials. How? Continue reading to find out:

Cement

All kinds of cement are susceptible to efflorescence, but according to the Brick Industry Association (BIA), Portland cement contributes most to it in mortar and grout. Its high alkali content makes it more likely to efflorescence than other types of cement.

Sand

While they are not water-soluble, you can contaminate sand with materials that contribute to efflorescence. Make sure the sand in mortar and grout are clean and free from contamination to reduce the chance of efflorescence.

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Brick

This type of building material may absorb soluble salts as it is porous. You can find out if there’s efflorescence in brick by immersing it in distilled water for seven days. White powdery substances will appear on the block if compared to a normal one.

Clay

The clay in building bricks and face bricks contain highly soluble salts, which may react to calcium sulfate that causes efflorescence.  Efflorescence caused by sulfates and hydroxides is more soluble than calcium, which makes them form more faster.

Lime

This building material has been known to improve the bond between brick and mortar. Lime also increases the water resistance of masonry materials. However, they are also soluble to water and can react with unbuffered hydrochloric acid to produce efflorescence.

Admixtures

It’s better to be cautious with admixtures as its bond and strength may increase the potential of efflorescences. You may want to avoid this solution if you’re unsure about admixture.

Conclusion

The best time to remove efflorescence is before it combines with carbon dioxide. You can rinse the efflorescences away by pressure washing or wet scrubbing them away. However, you must make sure there is no residue left on the building material, or new ones will appear.

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