The most practical and economical bonding agents are sand-cement and water-cement grouts. Epoxy resin grouts specially formulated for each application also are on the market. ACI 503 details the use and specification of epoxies for bonding fresh to hardened concrete.
You can patch concrete by pouring new concrete over old concrete. The problem is that dried concrete has no natural bonding agents and won't bond or stick well on another concrete material. You'll need a bonding adhesive to get wet concrete to bond to existing concrete.
Bonding Fresh Concrete to Existing Concrete Surfaces
Overlays or patching materials of new Portland Cement Concrete (PCC), terrazzo, mortar, grout and extruded curb based on Type I through Type V cements or White Cement may be structurally bonded with liquid epoxy adhesives to existing concrete surfaces.
Adiseal is the best adhesive to use on concrete as it has proven to be the strongest adhesive by an independent adhesive strength test.
Assuming that it is structurally sound, the least expensive alternative is to patch it. However, patching it requires some attention to detail or your patch will not last. Fact: Fresh wet concrete does not normally bond well to existing dry concrete.
Since cement lacks any natural bonding agents, newly-poured concrete won't naturally bond to the existing slab. You'll need to either use a bonding agent to adhere the two layers together or use an unbonded overlay method. Condition-affected life span: Properly installed concrete can last for over 50 years.
Quikrete 1 Qt. Concrete Bonding Adhesive permanently bonds existing concrete, plaster and stucco to new concrete, plaster and stucco.
A concrete bonding agent needs effective adhesion to work correctly, and latex, epoxy, acrylic, and polyurethane are some of the most effective options to choose from.
QUIKRETE® Concrete Bonding Adhesive (No. 9902) permanently bonds new concrete, plaster, and stucco to existing concrete, plaster, and stucco. Eliminates the need for roughing the surface before the application. Exceeds the performance requirements of ASTM C 1059 Type I and II.
You can pour concrete on top of an existing slab as long as it's still in reasonably good condition and structurally sound. This means the concrete should be free of cracks, buckling, and breaks. If you notice any small cracks or minor issues, it's in your best interest to repair them before you pour the new concrete.
Old, unneeded concrete can be recycled and used to create recycled aggregate. In most cases, recycled aggregate will be used as a subbase material, but it can also be paired with virgin materials and reused as an aggregate in new concrete.
REZI-WELD GEL PASTE is a two-component, moisture-insensitive construction epoxy, which can be troweled, brushed, injected, or pumped. REZI-WELD GEL PASTE is used to bond hardened concrete to fresh or hardened concrete. It can also be used to bond metals and other materials to hardened concrete.
Sugar can prevent concrete from setting too quickly and becoming unusable. Concrete that sets too quickly can become stiff and be challenging to use. For example, hardened concrete spreads less efficiently and can be ineffective in bonding or securing a structure.
Expansion joints are put in place before the concrete is poured. Expansion joints are used to allow the slab to move and not put stress on whatever it abuts. These joint are placed where a slab meets a building, where a slab meets another slab, and where a pool deck meets the coping.
Applying a bonding agent is an essential step that cannot be skipped. This substance acts as a bridge between the old and new concrete, improving the adhesion and overall strength of the bond. There are different types of bonding agents available, but the most common are latex-based or epoxy-based.
Especially for the construction industry (bonding concrete / stone to metal, e.g. aluminium), viscoplastic 2-component construction adhesives based on acrylate (fast initial strength) or epoxy resin (high final strength) such as Scotch-Weld 7271 B / A from 3M are suitable.
Structural bonding agent between old and new concrete
Epoxy based, two component structural bonding agent. Sika® Hibond compiles with ASTM 881 – 87 Type II Grade 2 Class B and C. Once the two components of the material is mixed the material must be used within approx 4 hours.
If the self-leveling compound is poured onto a concrete surface that has not been properly prepared, it will not be able to fully bond to it, and will instead cure as a layer separate from the slab, which will be prone to chipping away from the surface or crumbling.
QUIKRETE® Re-Cap® Concrete Resurfacer is designed to provide a new, durable, and wear-resistant surface over worn or scaled concrete.
And it's simple to apply on concrete to concrete surfaces. It has better bonding properties compared to other adhesives. You'll achieve exceptional bonding results if you follow the application instructions exactly, especially during the drying stage.
For smaller concrete gluing projects in and around the house, Loctite Extreme Glue Gel is the top choice. Its highly versatile formula contains Flextec technology which bonds quickly and allows for flexibility.
You can add a layer of concrete over an existing feature as long as you follow a few best practices to ensure the overlay concrete will adhere to the existing material properly. However, if the concrete structure has signs of damage, it's best to remove or repair it.