How to clean concrete
Contents |
[edit] Introduction
Concrete needs to be cleaned periodically both for reasons of aesthetics and to extend its lifespan. As dirt and grime can build up gradually on concrete surfaces, it is sensible to schedule cleaning at regular intervals. The technique for cleaning concrete depends on the type of surface. Specific stains may require cleaning chemicals, but water is usually sufficient for removing normal dirt.
[edit] External concrete
The most common method for cleaning external concrete (such as for the removal of oil and grease stains) is by using a power washer, which can often be rented. It is usually advisable to spray the surface with a detergent, or alkaline degreaser, and leave for 15-20 minutes before spraying with water. The degreaser has the effect of emulsifying the oil, allowing it to be flushed from the surface using hot water.
Power washers with a pressure rating of at least 3,000 psi and a flow rate of at least 4 gallons per minute should be used. However, difficult contaminants such as paint and heavy tyre-skid marks may require higher pressures. Power washers with a rotary nozzle instead of a standard fan nozzle can increase the cleaning speed. Use of a hand-held lance can direct the spray more accurately.
While it is less expensive and easier to use a cold-water power washer, hot-water units clean faster and more effectively.
Once the power washing is complete, the area should be checked, and any adjacent walls, windows, or other surfaces which have been dirtied should be washed down; usually without the high-pressure function, as normal mains pressure will suffice. Drainage points, gullies or linear channels should be checked for any blockages or silting from wash-off.
Depending on the chemicals used in the power-washing, water runoff may not be allowed to enter storm sewers. In addition, any detritus or dirt that accumulates should be disposed of off-site rather than allowed to wash into sewers.
More difficult stains, such as rust stains which have penetrated deep into the concrete surface, dried grout, or graffiti, may require muriatric acid or oxalic acid, albeit with extreme caution and protective equipment as they are toxic materials.
To tackle graffiti, several proprietary chemical strippers are available, of which, citrus-based solvents are the safest and have the least stringent disposal requirements, although they are the least aggressive and may not work on all types of paint. Products containing potassium hydroxide, which is soaked into the concrete surface for several hours, followed by the application of an acid neutralizer, can also be an effective solution.
[edit] Internal concrete
A less aggressive approach is required for cleaning internal concrete surfaces. It may be sufficient to use a mop and a bucket of water mixed with a mild cleaning product, followed by rinsing with a mop and clean water. Difficult stains can be removed by using trisodium phosphate (TSP) mixed with water and scrubbed onto the area with a brush.
A concrete sealant can be applied every 2 to 3 years to increase a concrete surface’s resistance to stains.
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
Retrofit 25 – What's Stopping Us?
Exhibition Opens at The Building Centre.
Types of work to existing buildings
A simple circular economy wiki breakdown with further links.
A threat to the creativity that makes London special.
How can digital twins boost profitability within construction?
The smart construction dashboard, as-built data and site changes forming an accurate digital twin.
Unlocking surplus public defence land and more to speed up the delivery of housing.
The Planning and Infrastructure Bill
An outline of the bill with a mix of reactions on potential impacts from IHBC, CIEEM, CIC, ACE and EIC.
Farnborough College Unveils its Half-house for Sustainable Construction Training.
Spring Statement 2025 with reactions from industry
Confirming previously announced funding, and welfare changes amid adjusted growth forecast.
Scottish Government responds to Grenfell report
As fund for unsafe cladding assessments is launched.
CLC and BSR process map for HRB approvals
One of the initial outputs of their weekly BSR meetings.
Architects Academy at an insulation manufacturing facility
Programme of technical engagement for aspiring designers.
Building Safety Levy technical consultation response
Details of the planned levy now due in 2026.
Great British Energy install solar on school and NHS sites
200 schools and 200 NHS sites to get solar systems, as first project of the newly formed government initiative.
600 million for 60,000 more skilled construction workers
Announced by Treasury ahead of the Spring Statement.
The restoration of the novelist’s birthplace in Eastwood.
Life Critical Fire Safety External Wall System LCFS EWS
Breaking down what is meant by this now often used term.
PAC report on the Remediation of Dangerous Cladding
Recommendations on workforce, transparency, support, insurance, funding, fraud and mismanagement.
New towns, expanded settlements and housing delivery
Modular inquiry asks if new towns and expanded settlements are an effective means of delivering housing.