(3) Cleaning: At the end of the injection operation, injection holes, spills, and excess resins and putties on the crack surface should be removed from the visible surfaces of the work. This can be done by sanding, shaving, or high-pressure waterjet. Prepared mortars or other suitable repair materials should be anticipated and applied to fill the injection cavities.
35- High molecular weight methacrylic sealing materials:
Sealing materials (see section 38) are used as a repair and maintenance method to prevent infiltration and leakage of water and liquids or protect concrete against destructive agents such as carbonate, melt and freezing processes, and degradation. Sulfates are considered protective. These materials are recommended as an alternative to flaxseed oil that has been mistakenly used for regeneration and repair.
These materials are produced in different membranes (such as paints and coatings) and penetrants on the surface and are supplied as sealing materials. Some of these materials can protect concrete for a long time. However, other branded sealants may be slightly more effective than minerals and flaxseed oil. Such systems, at best, cause less damage to the concrete. However, using these substances can prevent the use of substances that have been proven to have a positive effect. For this reason, only products whose efficiency has been proven during standard tests should be used for repairs and reconstruction. Some laboratories or standard institutes have provided a list of suitable sealing compounds to repair and reconstruct concrete structures.
One of the sealing compounds that has been effective in laboratory tests of restoration and executive operations is standard repair materials based on high molecular weight methacrylic monomer. This sealing compound, which consists of a methacrylic monomer and a suitable polymerization catalyst, is similar to the monomer system used in polymer concrete (Section 32). This liquid is thin and amber in color and can be applied by brush or spray on horizontal and vertical concrete surfaces. This liquid penetrates from the surface to a depth of 1.16 inches of concrete, but its most useful efficiency is penetrating and sealing concrete surface cracks. The function of this sealer is like membrane systems if a monomer is added to it or if two or more executive methods are used to make it. After its application, the appearance of the concrete surface is like wet surfaces with water or polishing paint, and it is possible to apply it on surfaces with high and low absorption. The coating applied to the concrete surface will be damaged and destroyed by direct sunlight after 1 to 2 years.
If the purpose of this coating is to penetrate and seal the cracks, its destruction due to sunlight is insignificant. If the methacrylic coating is applied properly, it is expected to last 10 to 15 years. After this time, it needs to be re-run. Figure 68 shows the application of high molecular weight methacrylic sealing compounds in the crown of the Kortes Dam.
A- Preparation: The concrete on which the methacrylic sealing compound will be applied must be dry, clean, and have a strong structure. Wet cracks and cavities mean that they are completely or partially filled with water, preventing the proper penetration of sealant compounds. The concrete surface can be considered for dry coating when two No moisture was observed when placing a transparent polyethylene sheet on the concrete surface and in full sunlight.
High-powered blowers can apply high-pressure air to the concrete surface to remove material and particles remaining on the concrete surface. The presence of paint, asphalt, rubber, or other similar materials with small dimensions on the concrete surface can be ignored. However, the methacrylic monomer system is expected to remove most of the stains and coatings deliberately left on the concrete surface. Worn and weak concrete must be removed according to the methods described in Section 8. After preparing the concrete surface, it must be protected from traffic and moisture.
B- Materials: High molecular weight methacrylic sealing materials are usually provided by manufacturers in a three-component system:
- A dilute liquid of methacrylic monomer
- Cumin (or catalyst) hydroperoxide initiator
- Cobalt nectarine promoter
Each manufacturer determines the appropriate ratio for mixing the three components, which must be carefully observed when consuming. As a general rule, primers of about 4 to 6 wt% and promoters of about 1 to 3 wt% are added to the monomer. Primer and promoter (promoter – should never be mixed directly with each other as this chemical process is explosive and dangerous. Instead, the primer must first be thoroughly mixed with the monomer, and then the promoter must be added to the monomer mixture).
Some manufacturers offer a two-part monomer system that contains the right ratio of the promoter. In this system, it is enough to add a certain amount of initiator to the mixture. After mixing the components, the sealing compound in the container has a short and specific life that can not be extended and continued under normal conditions of use.
For this reason, if the project requires a volume of more than 5 gallons of sealant compounds, usually the best way is to measure the required amount of monomer before starting the operation and place it in volumes of 5 gallons in places along the route separately. And is not mixed. In each place, 5 gallons of monomer, a specific and appropriate amount of primer, and a certain amount of promoter should be placed (unless the manufacturer supplied in two parts and combined with monomer).
When the first 5 gallons are consumed and completed during the executive operation, the next 5 gallons should be mixed and prepared. Because the resin flooring consumption galls are predetermined and measured, and then placed in place, it ensures the appropriate mixing components. Otherwise, some items may be added less or not added at all.
C- Execution method: Since the useful life of the resin is short at room temperature, so it should always be mixed and prepared in the amount of 15 to 20 minutes before setting if the sealing material is used by two workers, Runs and working conditions are convenient and accessible, usually mixing and preparing 5 gallons is appropriate, unless the ambient temperature is above 85 degrees Fahrenheit. Sealing resins should be used immediately after mixing. The use of injectable sealant resin floors against direct sunlight should be avoided. Sunlight shortens the life of the mixed resin.
Depending on the conditions and volume of work, workers can use various tees, industrial-sized paint rollers, brooms, brushes, or airless to perform. What is expected is to obtain a layer of durable sealing coating without weak, permeable areas or areas with over-applied amounts. Depending on the roughness and adsorption of the concrete surface, consumption is usually 75 to 100 square feet per gallon. The material should be applied on vertical surfaces in two or more layers by brush, sieve, or roller. The second and third layers should be applied immediately before the previous layer dries.
For surfaces resistant to machine braking or traffic, and should be sprayed on the work surface within 15 to 20 days of application. The grain size of the sand is equal to the specifications in the attached section. The amount of sand applied to the surface should be about 1.2 to 1.4 pounds per square yard.
D – Processing and protection: After execution, the work surface must be protected for at least 24 hours to perform processing. If the ambient temperature is less than 50 degrees Fahrenheit, the protection time should be increased to 48 to 72 hours for the curing operation to be completed. Execution operations are performed quickly during the night with sunlight the next morning. Performing operations at night allow maximum penetration of surface cracks, so you should try to perform operations at night if possible.
E-Safety: Safety rules are by the rules outlined in Section 33 to apply high molecular weight methacrylic coatings. It is forbidden to store the starter and the promoter in one place. The most desirable mode of storage of the starters is at low temperatures. Care must be taken to prevent mixing or contact of primers and promoters.
If you need more information, contact our resin flooring company .