Enhanced accelerated drying of concrete floor slabs

Concrete floor slabs dry out through a process of evaporation and diffusion provided the ambient environment promotes such drying. Impermeable floor coverings laid on concrete slabs can be subject to damage caused by high levels of residual moisture trapped by premature sealing of the surface. This damage can include timber floor boards buckling, vinyls blistering or tiles lifting. Whether or not it is safe to apply such a covering depends on whether the slab is sufficiently dry. Furthermore, if accelerated drying techniques are employed to reduce the waiting time before covering, the surface relative humidity reduces more rapidly, but there is an increase in the risk of damage to the covering because of higher levels of residual moisture deep within the slab. By using actual data from a variety of specimens to calibrate a non-linear finite-element model of the moisture migration, this paper shows how numerical predictions can be undertaken to determine a safer long-term relative humidity under an impermeable floor covering.