Exposed Aggregate Concrete in Nashville

Why Aggregate Selection Changes the Result Entirely

Exposed aggregate concrete is one of the most technically demanding decorative finishes in concrete construction. The window for exposing aggregate after the pour is narrow, too early and surface paste hasn’t set enough to hold the stone, too late and the paste is unworkable. Aggregate selection, surface retarder chemistry, wash timing, and exposure depth all determine whether the finished surface looks designed or accidental. Pumas Concrete approaches exposed aggregate with the same specification discipline as every other surface we build.

Specified aggregate, not default aggregate. We don’t accept whatever aggregate comes in the concrete mix and expose it. We specify the stone type, size, and color range, river pea gravel, quartz, granite chips, or mixed stone, to achieve the surface appearance the design requires. The aggregate blend is a design decision, made before the mix is ordered, not a result left to what the batch plant provides.

Retarder control on the day of the pour. Surface retarder application rate, chemistry, and coverage timing are managed on-site based on ambient temperature and concrete set time, which vary by day and season. Variable retarder application produces uneven exposure depth, the most visible quality failure in exposed aggregate work. We control this variable rather than leaving it to a fixed schedule.

Exposure depth specification. Exposure depth of one-third the average aggregate diameter is the specified target, deep enough to reveal the stone clearly and create traction texture, shallow enough to maintain the bond between aggregate and cement matrix. Over-exposed aggregate loses stone under vehicle traffic. Under-exposed aggregate loses its surface appeal quickly as the cement paste wears. The correct depth is specified, achieved, and documented.

For driveways, patios, walkways, and pool decks. Exposed aggregate is appropriate for any exterior surface in Middle Tennessee. Its natural texture provides excellent traction in wet conditions, and the aggregate material itself resists the freeze-thaw attack on the surface layer that smooth concrete finishes are vulnerable to. It is among the most durable exterior concrete finishes available when applied over a PSIP structural base.