Cracks in concrete and in wood beams are quickly, and permanently repaired by epoxy penetration injection. For a fraction of the cost of replacement, much more effectively than by mechanical means, epoxy injection restores the monolithic integrity of any foundation, wall, structural concrete or wood member to its pre-cracked condition.
Two things are necessary to a successful crack injection job: the right procedure and the right material. What follows is an outline of the procedure with some references to materials. In our experience, if a professional job is desired a trained professional is required. For referral to contractors in your area who have successfully completed the course of instruction and are RLBA certified in the application of our epoxy resins please contact us. Please be certain to read the "IMPORTANT" section at the end of this page.
1. Materials. Injection resin appropriate to the size and accessibility of the crack, mixing nozzles, injection tool and capping epoxy. Also required are wire brush, tongue depressors or putty knife, injection ports, safety glasses, and protective gloves. Optional supplies include bees wax, acetone for clean-up and, for hypersensitive individuals, barrier cream. Please note: exposure to and/or repeated exposure to ANY epoxy resin will cause skin rash in some individuals.
2. Surface Preparation. To ensure adhesion of the capping material, gently clean surface of concrete within two inches of the crack with a wire brush. Remove any debris, paint, or broken concrete. Blow away dust from surface with compressed air. Take care not to imbed dust or debris in the crack. To do so will impede the flow of the injection resin.
3. Port Mounting. Affix the ports to the crack at a spacing approximately the same as the thickness (depth) of the cracked member. Port spacing may be varied slightly to take advantage of more open spaces along the crack. If both sides of the member cannot not be capped, spacing may be reduced to avoid run out. The use of a thixotropic injection gel in cracks is 1/16 inch or more wide will also reduce run out.
In most cases surface mounted ports are recommended. At the appropriate spacing these are placed over the crack and held there by using a dab of fast set epoxy under the feet of the port until capping material is applied. Make sure not to block the port stem or the crack under it. Alternatively, lightly set a nail through the port stem into the crack. In the relatively unusual case when very high pressure is required or when the location of the port, at a corner for example, prohibits the use of a surface mounted port, the port can be drilled in. To drill in, drill holes the outside diameter of the port stem and as deep as the length of the port stem at appropriate spacing along the crack. Insert the port stem first, until the foott contact the surface of the concrete.
4. Capping the Crack. Capping the crack seals the crack to contain the injection resin until it sets. Choose the right capping material for your circumstance. Dispense the capping material along the crack with the appropriate dispensing tool and mixing nozzle. If a pneumatic dispenser is used, maintain the appropriate air pressure for the capping material you have chosen. Using a tongue depressor or putty knife apply capping to both sides of the crack. If only one side can be capped and the crack is 1/16 inch wide or greater, after capping has cured use a thixotropic gel for injection. Take care to seal the entire length of the crack with capping, and around the port feet to prevent resin from leaking out under pressure during injection. Apply capping material with a "buttering" motion to force it into surface pores and to prevent pin holes. In the event pinholes remain, bees wax can often be forced into the hardened capping material to plug the leak. Allow capping material to cure before beginning injection. Time of cure depends on capping material chosen.
5. Injection. Choose the right injection epoxy for your circumstances. Use the appropriate dispensing tool and mixing nozzle and, if a pneumatic dispenser is used, the appropriate air pressure for the injection epoxy you have chosen. If crack runs vertically begin Injecting at the lowest port. Continue to inject until epoxy shows at the next port. Plug the first port with the plug provided with the port. Continue injecting at the next port and so on. If the crack runs horizontally and is of similar width along its length begin at one end. If the width varies you may start injecting at the widest point and work toward the narrower. If this latter procedure is used, extra care must be taken to assure that no ports are missed. After the injected epoxy has cured some owners will require that the capping materials and ports be removed. StripSeal capping material can be peeled off. Other capping materials can be ground off. Alternately a torch can be used to soften the capping material sufficiently for a scraping tool to remove it. Take care to avoid overheating the concrete. There is no structural reason to remove the cap. We do not recommend doing so except for over-riding aesthetic reasons in which case we recommend the use of StripSeal for capping. Use proper dust and eye and ventilation if grinding or heating epoxy.
6. Quality control, Cartridge procedure. Both capping material and injection epoxies are often supplied in side by side cartridges. It is imperative that proper cartridge procedure be followed. Dispensing tools and mixing nozzles are NOT universally interchangeable. Be certain you are using the dispenser and mixing nozzle specified for the cartridge you are using. Before attaching mixing nozzle place cartridge in tool. If tool is pneumatic check that pressure does not exceed that specified for the cartridge you are using. Remove cap and sealing plug from cartridge. Hold tool upright so that open end of cartridge is up. Slowly activate tool until material on both sides of cartridge moves upward displacing any air. If necessary, discard some material from whichever side gets to the top first until air is displaced from both sides. Attach mixing nozzle. Again activate tool. Material from both sides of the cartridge will move through the nozzle. Discard the material that comes through nozzle until the light material and dark material comes out a completely uniform blended color. Now your cartridged material is ready to use. Continue to monitor for uniform color throughout the job.
Quality control, verification. During the job, periodically inject some of the injection resin into paper cups. An inch in the cup is sufficient. Tag the cup with the time and location along the crack. These can later be used to verify that the epoxy remained on ratio and cured properly. Aesthetic considerations permitting, to verify that adequate penetration was achieved 1" to 1-1/2" diameter core samples are taken with a diamond core bit. The cored area is then repaired with a cementitious or epoxy grout. Check with the engineer for approved core locations. If both sides of cracked member have been capped, inspection ports, a non-destructive means of verifying penetration can be used. Just as injection ports are applied on the side of the member to be injected, so are ports applied to the opposite side except at greater spacing. During injection these inspection ports will show that injection epoxy has penetrated the member. Make certain to plug the inspection ports as soon as epoxy appears.
7. Wood beam repair. Cracks in sawn wood beams, and delamination in glu-lam beams are repaired exactly as above EXCEPT: Core samples, if desired, cannot be cut with diamond bits, contact us for special depth hole saws, and we do NOT recommend removing capping material by use of heat. It may discolor or ignite the wood.
8. IMPORTANT. It is possible to inject into wet cracks, or substrates such as brick or stone, in abnormal temperatures, even in freezers or on the ocean floor. However, to do so you must contact us for additional instructions. The foregoing procedures are a broad overview. They are not intended as a complete manual for all possible circumstances. We have made every effort to provide you with accurate information and appropriate procedures but this should not be construed as a bond or guarantee of work performed. For further information please contact us.
