Concrete Cleaning
Many concrete surfaces accumulate dirt very slowly so it is difficult to notice the change in appearance. But when a concrete surface is cleaned, it is surprising how much better it looks. Scheduled periodic cleaning can avoid the gradual accumulation of dirt on concrete. The most effective way to clean concrete without damaging its surface is power-washing.
Cleaning equipment:
Power washers are the most effective way to clean concrete. Most power-washing equipments are easy to use and the cleaning procedures are quite easy. For effective cleaning, one should use a power washer with a pressure rating of around 3000 psi and a flow rate of about 4 gallons per minute. Although higher pressures may be required to remove tough stains such as paint and heavy tire-skid marks, but 3000 psi does the trick for almost all cleaning jobs.
Water temperature:
Power washers that use cold water are cheaper, lighter and simpler to use than hot-water units. However, hot water cleans faster than cold water even in power-washing. Cold-water units are suitable for removing dirt and are sufficient for smaller, residential applications. Most commercial power-washing is done with hot water as it especially effective in cleaning oil and grease.
Chemical cleaners:
Although water alone is able to remove dirt from concrete, cleaning chemicals are often required to remove specific stains. Spraying the stain with the chemical and letting it sit for about 15 minutes before power-washing is often recommended.
Oil, grease, etc - Removal of oil and grease from parking lots, drive-through and other concrete pavements is the most common concrete power-washing application. Apart from hot water, an alkaline degreaser greatly helps in removing oil and grease. Hot water lifts the oil from the concrete and the degreaser allows it to be flushed from the surface.
Rust - Rust stains can penetrate deeply into concrete and can be tough to remove completely. Chemical cleaners with oxalic acid are most effective.
Graffiti - Graffiti can be difficult to remove depending on the type of paint used. Citrus-based solvents are the least aggressive but are the safest to use. Cleaners containing potassium hydroxide if soaked into the concrete surface for several hours before power washing are quite effective.
By using the right equipment, water temperature and cleaning chemicals, all dirt and stains from concrete can be cleaned.