Our system to repair cold joints & cracks is with an epoxy resin injection with High or Low pressure. With this method, we can repair all kinds of concrete walls, slabs, columns and piers among other concrete structures, restoring the concrete to its pre-cracked strength.
Cold joints are formed primarily between two batches of concrete where the delivery and placement of the second batch has been delayed and the initial placed and compacted concrete has started to set. The full knitting together of the two batches of concrete under vibration to form a homogeneous mass is, therefore, more difficult, and sometimes not achieved. This could act as a potential plane of weakness.
Cold joints are not gaps in the concrete, but merely seams containing no appreciable void structure. They are usually linear, closely joined and bonded. However, there is a danger of small voids in areas where the concrete is not fully compacted, as with any concrete pour.
Generally, cold joints are not a problem structurally if the joint is under static conditions. Most civil engineers and on-site technicians forget the ‘if’ part. Cold joints perform poorly when transmitting the vibration energy generated by the machine; thus the upper part of the foundation, above the cold joint, is essentially the only one dampening the vibrations.
At the right, resin injection performed by Alphatec' grouting specialist.
Not all the cold joints are due to delays between concrete-filled trucks. Most of them appear because the foundation is complicated and is built in stages. For example, the foundation of a big diesel engine is built in many different stages, depending on the intricate of the foundation. This approach, though, prevents the foundation to act as a whole for inertia dampening and vibration absorber if cold joints are not addressed (At the left, epoxy resin flowing through a cold joint).
Using a small quantity of ALPHATEC® 440 as a bonding agent between pours will guarantee the correct transmission of vibration energy and will allow the foundation to act as a whole.
Watch how our resin injection works on this video on Alphatec YouTube Channel.
Epoxy grout specialists and concrete repair, Alphatec Engineering.