Decorative Concrete Information – Exposed Panels and Precast

Introduction

Exposed aggregate panels are helping architects, engineers and builders produce good-looking buildings at low costs. The technique combines the economy of tilt-up construction with the beauty of exposed aggregate.

The color palette of an exposed aggregate surface is largely determined by the type of decorative stone that’s used. Aggregate selection can also have a big impact on the total cost of the project. Expensive aggregates are not always needed to achieve impressive results.

Here are the main factors to consider when selecting aggregate:

• Colour
• Hardness
• Size and gradation
• Shape
• Method of exposure
• Durability
• Cost and availability

The most popular decorative aggregates are richly colored natural stones such as basalts, granite, quartz, or limestone. But you can also use manufactured materials such as recycled coloured glass. Even seashells and other interesting objects can be seeded into the concrete surface.

The color of natural aggregates can vary widely depending on their geological origin. Options range from delicate pastels such as pink or rose quartz, to rich hues such as dark blue or red granite, to earth tones such as sandy brown river gravel, black basalt, grey limestone and silver blue granite.

Caution: Avoid aggregates containing substances that can stain the concrete, such as iron oxides and iron pyrites  generally found in some gravels.

Aggregate size and shape vary, too. The size, which can range anywhere from 3mm to 50mm or more in diameter, largely determines the depth of exposure. Aggregate shape affects the surface pattern and texture. Rounded aggregates provide the best coverage and a smoother surface while angular aggregates add more texture and dimension. Avoid flat or sliver-shaped pieces; they don’t hold well during the exposure operation and can dislodge easily.

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