Epoxy Crack Injection

Cracking does not always affect structural performance, but it can adversely affect the durability of structures.

Common causes of concrete cracking are post cure and drying shrinkage, thermal stress, chemical reaction caused by alkali-reactive silica & sulfates, freezing and thaw cycles due to water expansion, corrosion of steel rebar, settlement, load stresses, construction short comings such as design and construction errors.

The incorporation of steel reinforcement within structural concrete allows these elements to function under both compression and tension, frequently resulting in tension-induced fracturing of the concrete in certain regions.

Water is a major contributor to concrete corrosion in parking garages, bridges, industrial facilities and more. Water, chloride and carbon dioxide can migrate deep into the structure  initiating corrosion of the reinforcement structure.

Water ingress, facilitated by fissures or compromised joints, often carries corrosive substances and chlorides that contribute to the degradation of concrete and the corrosion of steel reinforcements and rebar. Fortunately, epoxy concrete crack injection can address many of these concerns in structures exhibiting signs of such issues. Employing a proficient concrete repair team can frequently circumvent the need for a complete teardown.

SealBoss Epoxy Resins

SealBoss Epoxy Crack Injection resins for structural crack repairs conform to ASTM C881 specifications, with appropriate viscosities for the crack widths. The bond strength of epoxy to clean concrete is greater than the tensile strength of concrete itself.

Wider cracks may require a higher viscosity epoxy, small cracks a lower viscosity injection resin. Depending on the requirements, viscosities may range from approximately 150 to 600 cps at room temperature.

SealBoss Epoxy Crack Injection concrete repair can be performed with SealBoss Epoxy Cartridge Systems or SealBoss epoxy bulk resins using air guns, hand-actuated delivery systems,  or dual-component injection electric or air-driven pumps.

Prior to repair, the structure must be carefully examined to establish that epoxy crack injection is indeed the correct method to regain the desired structural integrity. The cause of cracking must be determined. Cracks must be identified and the allowable crack width needs to be established. The width of cracks can be measured by using crack gauge cards. In some instances it may be recommended to measure the expansion and contraction cycles of a crack. To determine the depth and cause of cracking, core samples can be taken and examined by petrographic and chemical testing. In addition, nondestructive testing (NDT) ultrasonic pulse velocity can be used to measure the depth of cracks.

Once it has been established that epoxy concrete crack injection is the chosen method of repair, the SealBoss Epoxy Injection System can be utilized to restore the structural integrity of the concrete. 

SealBoss ® Surface Mount Injection Ports

Surface-mounted injection ports are typically adequate for injecting most cracks. However, badly deteriorated concrete or higher injection pressures may require the use of drill-in or hammer-in plastic ports or even mechanical packers. Surface ports, aka plastic tubing ports, are glued on the surface over the open cracks using SealBoss epoxy paste adhesive. The injection ports are typically installed at a spacing that is equal to or slightly narrower than the depth of the crack. Hairline cracks require closer spacing than wider cracks.

Wire brushing and vacuuming the crack surface along the crack is often sufficient for surface preparation. In areas of badly deteriorated concrete, pressure washing, grinding, and V-grooving may be specified.

After the surface has been cleaned, surface ports are installed. Sealboss 4500 crack-sealer epoxy paste will be used as surface port adhesive and be applied on the face of the crack between and around the ports.

Once the injection ports are installed, Sealboss 4500 crack-sealer epoxy paste is applied on the face of the crack between and around the ports. To contain the epoxy resin in the crack until it hardens, it is a good practice to seal cracks on all sides of the substrate if possible.

Epoxy Injection Preparation Tips – Installing Surface Mount Tri-Base Ports

Epoxy Injection is a typically a low pressure to medium pressure crack filling solution where all sides of the crack are sealed and structurally glued together with a high strength low viscosity Epoxy Resin.

To prep for injection, the crack must be cleaned with a wire brush and all dust removed. Any surface contaminants, such as oils or paints, must be removed for the epoxy paste-over to bond properly. If available, use clean  compressed air to remove any dust and debris. For best results perform epoxy injection preparation when the crack and surface are dry. Any water seeping from the crack should be stopped prior to epoxy injection. For sealing water bearing cracks click here.

Once the surface is cleaned, the Surface Mount Epoxy Injection Ports are installed directly over the crack 6” – 8” (15-20 cm) apart. The finer the crack, the narrower the spacing should be.

Shown in this example are standard surface mounted Tri-Base ports, however corner ports and ½” drill in ports are available for specific applications.