General Cleaning and Maintenance
Is concrete difficult to clean and maintain ?
Concrete can be washed with clean water, applying a stiff-bristled deck broom to stubborn areas of stain or mould.Concrete can be protected against staining by applying a suitable clear sealer. This will seal the concrete surface and provide long-term protection against most stains penetrating the concrete surface. A suitable protective paint coat may be applied to concrete pavements, but as concrete pavement surfaces are subject to the abrasive effects of tyres and foot traffic, sealants or paint coatings may need to be periodically reapplied to maintain consistent protection of the concrete surface. It is always better to wash unsealed concrete surfaces with water as soon as common spillages occur to avoid surface penetration of the concrete.
The use of diluted hydrochloric acid or chemically based cleaning agents to clean concrete can be hazardous if used incorrectly. Read manufacturer's instructions before use. Observe safety advice and recommended dilution. Wear suitable protective clothing at all times.
Methods of Removing Common Stains
A small trial area should be done in an inconspicuous location to check the effect of the method of cleaning on the concrete.
Common Grime and Dirt
The simplest and quickest method is to clean with a high-pressure water cleaner.
Solidify the gum with ice cubes then scrape off as much as possible. Make a poultice impregnated with methylated spirits. To make a
poultice, use 'Kitty Litter' or similar inert absorbent material. Apply the poultice to the gum. Leave until dry. This should turn the residue gum brittle, making removal possible with a stiff bristle or wire brush. Finish by washing affected area with hot soapy water, then rinse with clean water.
Clay Soil and Common Beverage Stains
Scrub stain vigorously with warm soapy water. Rinse with clean water. Stubborn stains may require scrubbing with chlorine bleach. Wet surface first, then apply bleach, scrub and rinse thoroughly.
Scrub stain vigorously with warm soapy water. Rinse with clean water. If this is not effective, try a poultice (use 'Kitty Litter' or similar inert absorbent material) saturated with a solution of 1 part glycerol and 4 parts water. Allow to react with the stain before hosing affected area. Residual
stain may require surface scouring with grit-scrubbing powder.
Efflorescence (Soluble Salt Deposits)
First, remove excess salt deposit with a stiff bristle broom Scrub with clean water then rinse from surface.
Insoluble White Deposits (Insoluble Salts)
Remove excess salt deposit with a stiff bristle broom. Wet concrete surface thoroughly. Use a soft broom to apply a diluted solution of 1 part hydrochloric acid to 20 parts water. Rinse surface thoroughly immediately after.
Hydrochloric Acid - avoid contact with skin. Wear protective clothing. Add acid to water. Seek handling advice from supplier and follow
label instructions as dilution specifications may vary. Be aware that acids can acid-etch the concrete surface if not used with care and washed off immediately afterwards.
Cover stain with a poultice (use 'Kitty Litter' or similar inert absorbent material) impregnated with a solution of 1 part sodium citrate
and 6 parts warm water. Remove when dry. Scrape off residue then scrub with warm soapy water. Rinse with clean water.
Wet concrete surface. Apply chlorine bleach and scrub vigorously. Rinse thoroughly. A deposit of dead fungal residue will usually be noticeable within a few days. Brush with a stiff bristle broom and repeat cleaning process.
Alternatively, use a high-pressure water cleaner to remove fungal growth, then broom chlorine bleach over the surface. Rinse thoroughly.
Oil and Grease Stains
These can be difficult to remove completely because of their rapid penetration of the concrete surface. If an oil spill occurs, stop it spreading by encircling with sand or dirt. Soak up as much surface oil or grease as possible with an absorbent cloth or powder. Cover residue stain with a 5-mm-thick poultice made of 1part lime and 2 parts mineral turpentine.
Cover with plastic sheet and leave for 24 hours. Remove plastic and scrape off the powder. It may be necessary to repeat this process again within a day or so to remove any deeply ingrained oil or grease that sometimes diffuses to the surface. Scrub with warm water and laundry detergent at the end of the treatment.
A lime/turpentine mixture can be used to lessen oil and grease stains
Use proprietary rubber removal compounds.
Seek accurate advice from the supplier regarding manufacturer's recommended preparation and application and what effect, if any, might the rubber removal compound have on the concrete surface.
Scrape off excess paint as much as possible. Cover residue paint with a commercial paint remover for 20-30 minutes.
Observe paint remover manufacturer's safety and handling instructions. Wear protective clothing.
Scrub stain gently to loosen paint film then wash surface thoroughly with clean water. Stubborn to remove surface paint film may require additional scrubbing with a scouring powder. Ingrained paint may be further treated with 1 part hydrochloric acid diluted in 20 parts water. Wet the surface before application. Flood surface with clean water immediately after acid treatment.
Soak up excess paint with absorbent cloth or paper towels. Do not wipe or rub as this will only spread the paint spill and drive it further into the surface. Immediately scrub the affected area with scouring powder and water until there is no further improvement. Wait at least three days then use the Dry Paint removal technique described previously.
Paint removers or solvents used to remove wet paint film deposits in less than three days may result in spreading the stain and increase the risk of deeper surface penetration.
Scrub vigorously with chlorine bleach then rinse the surface. Cover residue stain with a cloth soaked in bleach, repeating this process until a satisfactory result is achieved. Scrub regularly between bleach treatments. Rinse thoroughly.