Cleaning, Sealing and Maintenance of Olsen Interlocking Concrete Pavers
When properly installed, Olsen interlocking concrete pavements have very low maintenance and provide an attractive surface for decades. Under foot and vehicular traffic, they can become exposed to dirt, stains and wear. This is common in all pavements. Maintenance ensures the durability of interlocking concrete pavements and helps restore their original appearance. These steps include removing stains and cleaning, plus joint stabilization or sealing if required. Stains on specific areas should be removed first. A cleaner should be used next to remove any efflorescence and dirt from the entire pavement. A newly cleaned pavement can be an opportune time to apply joint sand stabilizers or seal it. In order to achieve maximum results, use stain removers, cleaners, joint sand stabilizers, and sealers specifically for concrete pavers. These may be purchased from a manufacturer, contractor, dealer or associate member of the Interlocking Concrete Pavement Institute.
Overall cleaning of the pavement can start after stains are removed. In preparation for cleaning, low tree branches, shrubs and vegetation adjacent to the pavement should be tied back or covered to protect from over spray of cleaning solutions or sealers. The area should be inspected for any cracked or broken units. These should be replaced. Badly stained units can be replaced, but it is usually easier to clean stains and less costly than replacing the pavers. When pavers have stains too difficult to remove, replace them with the same type of units. Refer to ICPI Tech Spec 6, Reinstatement of Interlocking Concrete Pavements, for a full description on replacing pavers. If pavers must be replaced, there may be a difference in color from the surrounding pavers. This variation should eventually disappear. If color variation is unacceptable, controlled use of proprietary cleaners designed to improve the color of concrete pavers can minimize variation. Removal of accumulated dirt and efflorescence is the objective of cleaning. It is essential in preparing the pavers for sealing as well. Many cleaners effective in removing dirt and efflorescence are a mix of detergent and acid. Cleaners with strong acids will change the color of the pavers slightly. The degree of change can be controlled by the type of acid in the cleaner, its concentration and the length of time on the pavers. Proprietary cleaners will give specific instructions on their application. These directions should be followed. In order to achieve proper results, cleaners should be tried on a small area to test results and any color changes. The concentration and time on the pavement can be adjusted accordingly. Protective clothing and goggles should always be worn when using acidic solutions. Anticipate where the cleaning fluids will drain, i.e., across the pavement and not onto grass or vegetation. Sediment or cleaners allowed to pond in low spots may stain the pavers. If unsure of the runoff direction, test drainage with ordinary water first to identify any trouble spots. Be sure to rinse these areas thoroughly. Turn off all automatic sprinkler systems during cleaning, sealing and drying.
Professional Cleaning Methods
For most jobs, cleaning should be handled by a professional company experienced in the use of cleaners and spray equipment. Professionals typically use a pressure washer and an applicator to apply efflorescence cleaner (when needed). The various methods for applying joint sand stabilizers and sealers are covered later. A high pressure sprayer applies cleaner and water between 600 and 2,000 psi (4.1 and 13.8 MPa), and at a rate between 6 and 12 gallons/minute (22 and 45 liters/minute). See Figure 2. The rate of flow is adjusted to ensure sufficient rinsing. The pressure loosens dirt and pushes water from the surface without the need for scrub brushes. The nozzle type and its distance from the paver surface influences the effectiveness of the cleaning as well. A nozzle that creates a wide spray enables a large area to be covered efficiently and prevents sand from being washed from the joints. A low angle of attack from a wide nozzle spray will also reduce the risk of dislodging joint sand. Cleaners to remove efflorescence are applied with a low pressure pump spray 30 to 100 psi (0.2 to 0.7 MPa). A shower type spray nozzle will help ensure even distribution of the cleaner. Cleaning chemicals are applied, allowed to sit an appropriate time, then rinsed away with a high pressure sprayer. The final rinse should be water only. A large amount of water is more important to rinsing than high pressure. For small areas, an adequate cleaning job can be achieved without this equipment. Such areas include residential patios, walks, or small driveways. Cleaners can be applied by hand, the pavers scrubbed to remove dirt and efflorescence, then thoroughly rinsed with water from a garden hose. Scrub brushes with steel bristles are not recommended. They will loosen from the brush, rust, and leave stains. Brass or plastic bristles are acceptable. This method of cleaning is for do-it-yourselfers who wish to refurbish a small area of pavers. The additional time required to clean and seal pavers without the help of a professional should be weighed against investing in a competent company to do the job. Professionals have the equipment and experience with the various chemicals. They can achieve the highest level of results in the least amount of time.
Removal of Common Stains
There are proprietary cleaning products specifically designed for concrete pavers. Many have been developed through extensive laboratory and field testing to ensure cleaning effectiveness. These chemicals should be used whenever possible. Using manufactured cleaning chemicals for specific stains relieves the user from the uncertainty of attaining the proper mixture of chemicals. Olsen Pavingstone does not take responsibility of any chemicals used in the removal of stains or the actions caused by using chemicals on pavers. Olsen will not be held responsible for any end result of using chemicals to clean paving stones. The user is advised to use cleaners specifically made to remove stains that commonly occur on concrete pavers. They will likely be more effective. Always do a test sample in a small area before using anything to see if it meets your desired outcome.
Underground Utility minor repairs, Reinstatement of pavers
Please review ICPI's recommended Reinstatement and repair section in ICPI Tech Spec #6.
SURE BOND SEALING PROCEDURES AND CLEANING/ MAINTENANCE
All dirt, oil stains and efflorescence must be removed prior to sealing. The cleaned surface must be completely dry prior to applying most sealers. Allow at least 24 hours without moisture or surface dampness before application. The pavers may draw efflorescence to the surface, or the sealer or liquid stabilizer may whiten under any one of these conditions:
• The surface and joints are not dry
• The pavers have not had an adequate period of exposure to moisture
• There is a source of efflorescence under the pavers (i.e., in the sand, base, or soil) moving through the joint sand and/or pavers
• The sealer is not breathable, i.e., does not allow moisture to move through to the surface of the paver and evaporate.
If the base under the pavers drains poorly, the sealer is applied to saturated sand in the joints, or is applied too thick, the sealer can become cloudy and diminish the appearance of the pavers. In this situation, the sealer must be removed or re-dissolved. Consult your sealer supplier for advice on treating this situation. Cover and protect all surfaces and vegetation around the area to be sealed. For exterior (low-pressure) sprayed applications, the wind should be calm so that it does not cause an uneven application, or blow the sealer onto other surfaces. For many sealers, especially those with high VOC's, wear protective clothing and mask recommended by Sure Bond Int, to protect the lungs and eyes. Sure Bond sealer can be applied with a hand roller if the area is small (under 1000 ft 2 or 100 m 2 ). For larger areas, more efficient application methods include a powered roller, or a low pressure sprayer. Sealers are often applied with a foam roller to dry pavers having clean surfaces and chamfers. However, the use of a squeegee to spread the sealer will avoid pulling joint sand out of the joints. Sure Bond Sealer should be spread and allowed to stand in the chamfers, soaking into the joints. Penetration into the joint sand should be at least 3 / 4 inch (20 mm). The excess sealer on the surface is pushed to an unsealed area with a rubber squeegee. The action of a squeegee wipes most of the sealer from the surface of the pavers while leaving some remaining in the chamfers to eventually soak into the joints. Generally only one coat is required. For other applications, follow the sealer manufacturer's recommendation for application and for the protective gear to be worn during the job. With some sealers that recommend two coats, the first coat is usually applied to saturation. Be careful not to over apply the sealers such that the surface becomes slippery when cured. Prevent all traffic from entering the area until the sealer is completely dry, typically 36 hours. If spraying sealer on the pavers, care should be taken to prevent the spray nozzle from clogging and causing large droplets to be unevenly distributed on them. This is most important for water based sealers. This can cause a poor appearance and performance. Sealers normally require reapplication after a period of wear and weather. The period of reapplication will depend on the use, climate, and quality of the sealer. Typically every 2-3 years. Jobsite cleaners by Sure Bond Int may be used before resealing of pavers in Vehicular areas to help remove tire tracks and also in food courts to help remove food grease stains. To maintain the pavers after time you may also use the Job Site Cleaner to clean the pavers before resealing them with a Sure Bond product. Also make sure that the surface once again is dry and free from debris along with refilling of sand joints (if needed) is completed before the resealing process is started. Always do a small test area first.
HOTEL/RETAIL/FOOD COURT REGULAR MAINTENANCE
If you are maintaining a high traffic area, or an eating area on a weekly basis than here are some helpful tips.
- Do not Pressure wash daily. Weekly, monthly, or annually is ok.
- Remove all stains with Sure Bond jobsite cleaner before sealing.
- Do not set pressure washer to high setting.
- Hot water IS helpful.
- Sweep area free of debris first.
- Hold pressure washer wand at angle when cleaning.
- Hold wand tip 12-14 inches away (above) from pavers so not to blast away smooth finished top. Holding too close will expose aggregate on top of the paver, and will start to remove any sealer applied.
- Do not blow out sand in the joints.
- If desired you may refill sand joints with Olsen's Polymeric joint sand. See paver manufacturer if needed. If there is any rutting in pavers due to poor installation, base failure, tree roots, plumbing breaks, improper load capacity's on pavers, utility repairs, or broken pavers please follow instructions given by ICPI in Tech Spec #6 or refer to link above under the heading Reinstatement of Pavers to see how repairs are made.
- Reseal with a Sure Bond Sealers (avail @ Olsen) when and if needed. Sealing should be every 2-3 years.
Efflorescence and Its Removal
Efflorescence is a whitish powder-like deposit which can appear on concrete products. When cement hydrates (hardens after adding water), a significant amount of calcium hydroxide is formed. The calcium hydroxide is soluble in water and migrates by capillary action to the surface of the concrete. A reaction occurs between the calcium hydroxide and carbon dioxide (from the air) to form calcium carbonate, then called efflorescence. Efflorescence does not affect the structural performance or durability of concrete pavers, and does not make the paver defective. The manufacturer is not liable for any instances of Efflorescence. The reaction that takes place is the formation of water soluble calcium bicarbonate from calcium carbonate, carbon dioxide and water. It may appear immediately or within months following installation. Efflorescence may reach its peak in as short as 60 days after installation. It may remain for months and some of it may wear away. If installation takes place during dry period of the year, the next cycle of wet weather may sometimes be necessary for efflorescence to materialize. If there is a need to remove deposits before they wear away, best results can be obtained by using a proprietary efflorescence remover. The acid in proprietary cleaning chemicals is buffered and blended with other chemicals to provide effective cleaning without damage to the paver surface. Always refer to the paver supplier or chemical company supplying the chemicals for recommendations on proper dilution and application of chemicals for removal of efflorescence. They are generally applied in sections beginning at the top of slope of the pavement. If the area is large, a sprayer is an efficient means to apply the cleaner. The chemicals are scrubbed on the surface, then rinsed away. Results can be verified after letting the area dry for at least 24 hours. In most instances one application is sufficient. However, in severe instances of efflorescence, a second application may be necessary. Contact the manufacturer of the cleaning product to determine if a second application will not discolor the pavers or expose some aggregates. Note: Protective clothing, chemical resistant rubber boots and gloves, and eye goggles should be worn when applying acid or alkalies.