What Cause Empty Drums and How to Find Out

In addition to ash and sand, there are other problems on damaged concrete flooring, such as empty drums. The empty drum is a delamination phenomenon caused by the adhesion and the joint between the leveling layer and the base layer. The empty drums part is generally slightly higher than the overall around, and often accompanied with cracks,and is empty inside. The empty concrete floor is prone to cracks and holes, and aggravates them.

What cause empty drums??

★ Concrete Shrinkage

In traditional screed construction,usually clean the base concrete at first, then cast 8-10 cm concrete with fine stone concrete and level the concrete. Due to the large shrinkage deformation of the cement slurry, the adhesion is insufficient, which makes the leveling layer and the structural layer easy to be disengaged, and empty drum or crack occurs. In addition,the difference in shrinkage between the base concrete and the surface concrete may also cause empty drum.

★ The interface cleaning is not complete.

Generally,the base concrete is cleaned before leveling,but the actual operation often cannot clean the dust completely. And the surface of  concrete will have floating slurry which can't be cleaned. It is generally recommended to grind off,otherwise, the slurry and dust will act as an isolation, resulting in an empty drum.

★ Reinforcement

If steel bars are added during screed construction, the steel bars themselves will have a certain amount of stresses and play a role in isolation,which may lead to an empty drum.

★ Expansion joints: 

Empty drums often appear on both sides of the expansion joint. The general theory is that it is caused by the vibration during the cutting process. According to the investigation of concrete for many years, this is the shrinkage of the concrete itself. The expansion joints are cut after pouring concrete.The four sides of the concrete will naturally warp and shrink upwards. Therefore, most of the project expansion joints will have empty drums on both sides.

In a words,it is necessary to first check the floor surface before starting the construction project of polishing concete.

How to know where the empty drum is??

In High Tech Grinding testing instrument includes an empty drum hammer. The empty drum hammer is used to test whether there is an empty drum on the ground. Come and knock on the ground one by one, if the place is humming, then it will be an empty drum.