The Matrix Matters

Concrete is a composite material, and while the cement paste controls the chemical hydration, the aggregate (sand, gravel, crushed stone) occupies 60-75% of the volume. For flooring professionals, understanding the aggregate profile is essential for predicting moisture behavior.

Porosity and Absorption

Aggregates vary significantly in porosity. Lightweight aggregates (LWA), often used to reduce dead load in multi-story buildings, are highly porous. They absorb water during mixing and release it very slowly.

• The Risk: A slab with LWA may appear dry on the surface but hold a massive reservoir of moisture internally.
• The Testing Implication: Standard drying times do not apply. Extended drying periods and rigorous ASTM F2170 testing are critical to prevent “rewetting” of the slab-to-adhesive interface.

Structural Integrity vs. Flooring Compatibility

While concrete is often cited as the “strongest building material,” its interaction with modern flooring adhesives is chemically complex. IFTI’s diagnostic services help engineers balance the structural requirements of the mix design with the finishing requirements of the flooring contractor.

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