Why understanding what happens inside a concrete slab matters before resin flooring installation
Technical Insight • Premier Flooring Systems Ghana
The hidden factor beneath every successful resin floor
A concrete slab may look dry, hard and ready for coating, yet moisture can still be moving through its internal pore structure. For epoxy and other resin flooring systems, understanding that behaviour is fundamental to making sound installation decisions.
Concrete is not a completely solid, impermeable material. It is a porous composite containing interconnected capillary pores, gel pores, air voids and microcracks through which water and water vapour can move.
Concrete remains porous after it hardens
Concrete is produced from cement, water, fine and coarse aggregates, with optional admixtures. During hydration, cement reacts with water to form calcium silicate hydrate (C-S-H) and other compounds that bind the concrete together. Although strength develops over time, the hardened material still contains pores and retains internal moisture.
Not all water in concrete behaves the same way
Concrete can contain chemically bound water, capillary water, gel water and free water. From a flooring perspective, capillary water is particularly important because it is closely associated with moisture-related flooring failures.
The water–cement ratio influences long-term behaviour
A higher water–cement ratio generally increases porosity, permeability, drying time and shrinkage while reducing strength. For industrial floors, controlling this ratio is therefore important not only for concrete quality but also for the conditions that a subsequent resin flooring system will encounter.
Porosity, permeability and moisture movement
Porosity describes the amount of void space within concrete. Permeability describes how easily moisture can move through those voids. Both matter, but permeability is especially relevant when evaluating flooring performance.
Moisture can move by capillary action without external pressure. Water vapour can also diffuse through concrete because of differences in vapour pressure and relative humidity. Once an impermeable coating is installed, this moisture may become trapped beneath the flooring system.
Why internal relative humidity matters
Internal relative humidity provides a direct indication of the moisture condition within a slab. ASTM F2170 measures internal RH and is used to assess the moisture condition beneath an installed flooring system.
Concrete age alone does not prove dryness
Drying is influenced by slab thickness, environmental conditions, water–cement ratio, curing and the presence or absence of vapour barriers. Temperature, humidity, ventilation, rainfall and seasonal conditions can all affect moisture behaviour. A slab’s age by itself is therefore not a reliable indicator that it is ready for resin flooring.
The role of vapour barriers
A properly installed vapour barrier beneath a slab reduces moisture migration and can improve long-term flooring performance. Knowing whether such a barrier is present is an important part of pre-installation assessment.
| PREMIER FLOORING SYSTEMS BEST PRACTICE
• Verify the slab history. • Confirm whether a vapour barrier is present. • Record environmental conditions. • Perform recognised moisture testing. • Compare test results with the flooring manufacturer’s requirements before installation. |
The practical takeaway
Understanding concrete science helps flooring professionals interpret moisture test results, identify risks and determine when mitigation systems may be required. Concrete remains porous throughout its service life, so hydration, pore structure, permeability and moisture movement must be considered when assessing readiness for a resin flooring installation.
The strongest flooring specification can still be undermined by an inadequately assessed substrate. Effective moisture evaluation begins with understanding the concrete itself.
About Premier Flooring Systems Ghana
Premier Flooring Systems Ghana provides technical flooring solutions with an emphasis on substrate assessment, disciplined preparation and appropriate resin flooring system selection for demanding environments.