The concrete floors have diferential movements as caused by the dry shrinkage and thermal changes, so that´s why the Contraction Joints needs to be use it.
If a concrete floor doesnt have a contraction joint, this will be reproduce randomly in forms of cracks.
Controjunta is a pre-molded plastic profile that prevents random cracks, forming a straight joint and precise on the surface of the concrete floor. It is the most efficient and economic method to create a perfect seal contraction, when concrete is in fresh state, until the cracks come to occur.
Controjunta it is placed inmediately after of extending and leveling the smooth concrete, marking it with thread or rule in the designed area for the joing, making a light groove in the fresh concrete with a trowel or spoon.
Controjunta must be aligned and insertted into the slot until the lid stabilising reaches the level of the surface. The cover must be removed to be able to finish, either manually or with mechanical bulldozer. You must ensure not to sink the Controjunta, nor let it overhung or much less inclined.