We have all have encountered it from time to time… the dreaded soft concrete floor!
The customer wants it polished — and you immediately want to run!
Sometimes, though, a simple modified densifier application process may be all you need to create a polished concrete floor that has good reflectivity, the expected final shine, and the long-term durability that you’re seeking. It just requires being innovative during the densifying step.
Best Practices: Perform a Mock-up First
As with best practices performing any chemical-densifying, mechanically-polished process, a representative sample area (mock-up) should be done first to test and understand that particular slab’s density and strength.
Polished concrete success not only relies upon a minimum PSI and the right combo of concrete chemistry, but also on a carefully planned polishing process that caters to that individual slab’s properties.
You can definitely achieve the final result you want IF you know what steps to do from the onset.
Where did my densifier go?!
In the case of soft concrete (as well as when ambient temperature exceeds 80 degrees), the concrete slab will exhibit a very high rate of absorption and evaporation. This means there will be the likelihood that the chemical densifier will lose its liquid viscosity before the densification reaction has time to take place. No densification means no hardened surface to polish.
The reason for the low liquid viscosity is that the water content in the densifier is evaporating or being absorbed so rapidly that the densifier dries prematurely.
Normally, the solution is to add more densifier, but this option adds more cost to the project and does very little to aid the densification process.
A Modified Densification Process Can Make a Difference
An alternative method to densifying a very porous or hot slab is to pre-dampen the concrete with water. This is achieved by dousing the slab with enough water that it wets the entire surface, fills the concrete pores, and cools the slab.
It’s important, though, to note that before performing the densification step, the slab should only be damp — NOT wet. In other words, water should not visibly standing on the floor surface. This extra water will dilute the densifier and reduce its chemically-reactive affect.
A crucial step in this modified process is squeegee or autoscrub the floor surface in order to remove all standing water BEFORE applying the densifier. Then, you can proceed with standard application of the densifier as specified by its manufacturer’s instructions.