Green algae would begin to grow on cement surface because of the constant dampening condition. Though it does not affect the structural activity of the cement or the concrete, it can cause troublesome problem and making the surface slippery thus creating safety hazards on the walkways.
There are some tips to handle this stubborn issue-
1) Use Boiled Water -
Get a bucketful boiled water and this needs to be poured on the surface carefully. Now with the help of a stiff brush, scrub the portion which is affected. Finally, using a hose, wash away the debris.
2) Explore the surface in the dry state -
Create a condition so that the area turns to dry even if it requires a fan operating on a high speed or a heater helping it to make it dry. Once the area is free from moist, use the stiff brush on the entire affected area. For more stubborn surface, a plastic scrapper for the removal of debris would be more effective.
3) Apply a pressure washer -
A pressure washer directs the stream of water through its nozzle into the surface. This requires the selection of a correct nozzle ensuring that you achieve a fast and effective removal process with absolutely no damage to the surface. This has to be connected to a source of water and the ejection of of water is adjusted with a high speed by means of power.
Regulate the pressure in such a way that this does not create the condition of damaged structure.
4) Steam Cleaning -
Steam Cleaning is the process of killing algae and its removal from the surface with the mechanical means. Water is to be loaded in the steam cleaner and let it be allowed to warm up for sometime and once it heats up properly, blast the algae with the spurts of the steam. Once the operation is complete, leave it for an hour so that the debris is soaked with the hot water and finally this has to removed by means of a hard scrubber.
5) Use the commercial products-
If the algae issue is of mild nature, opt for a mold stain remover. This product needs to be sprayed as per direction appearing on the label of the product. Spray the product and wait for 10 to 15 minutes to allow it for the reaction with the algae. Scrubbing is to be continued with a hard brush and finally rinse the surface with a water hose.
In order to avoid the contact with the algae spores, it is always desirable to use a rubber gloves on hands and a face mask to avert the spore inhalation.