ACI Decorative Flatwork key terms

A decorative flatwork method in which patterns and textures are pressed into freshly placed concrete with mats or stamps to imitate stone, brick, tile, or wood. Color hardeners and release agents are usually part of the process.

A dry shake product of cement, graded aggregate, and pigment broadcast onto fresh concrete and floated in. It densifies the surface and adds a wear-resistant, colored layer at the top of the slab.

Pigment added to the concrete mix itself so color runs throughout the slab rather than only at the surface. It gives more uniform tone but tends to appear more muted than surface-applied coloring methods.

A powder or liquid applied between stamps and concrete so stamps lift cleanly without sticking or tearing the surface. Powdered releases also add accent color that is later washed or scrubbed away.

A finishing step that leaves some release agent or a contrasting stain in the low areas of a textured surface to deepen shadows and add an aged, variegated look. Excess material is removed from high spots.

A thin, flexible stamp or mat used to imprint surface texture such as slate, stone, or wood grain without creating deep joint lines. It is often used to break up the look of large stamped areas.

A finish produced by removing the top layer of cement paste before it fully hardens so the aggregate beneath shows. Methods include water washing, brushing, and chemical surface retarders.

A chemical sprayed on fresh concrete that slows set in the top few millimeters only. After the bulk of the slab sets, the softened paste is scrubbed off to reveal aggregate for an exposed finish.

A standard slip-resistant texture drawn across fresh concrete with a stiff-bristled broom. In decorative work the broom direction and timing are controlled to keep the pattern even and attractive.

A smooth, dense surface produced by machine or hand troweling after the concrete has stiffened. Overworking a troweled surface can draw excessive paste and water to the top and weaken it.

A light exposed-aggregate look where only a small amount of paste is removed, leaving fine aggregate and small stones visible. It is achieved with a mild retarder or a light wash.

A straight groove cut into hardened concrete to create a controlled contraction joint. In decorative work cuts are often laid out to match the pattern so joints read as part of the design.

A groove formed in fresh concrete with a groover or jointer to control cracking and separate panels. Decorative work often uses groovers sized and shaped to mimic grout lines in the imitated material.

A planned plane of weakness that tells the concrete where to crack as it shrinks. Joints must be deep enough and spaced closely enough to work, and they must be cut before random cracking starts.

The plan for where joints, borders, and pattern lines will fall on a decorative slab. Good layout balances panel sizes, aligns with the pattern, and avoids awkward slivers at edges and corners.

A coating or penetrating treatment applied to cured decorative concrete to protect against stains and moisture and to enhance color. Film-forming sealers may need reapplying and can trap moisture if applied too early.

The ability of a finished surface to resist slipping when wet. Decorative textures and sealers both affect it, and highly polished or heavily sealed surfaces may need additives or a different finish.

A reactive or film-forming product applied to cured concrete to add color or mottled effects. Reactive stains react chemically with the concrete, so results vary with surface condition and application technique.

A band of contrasting color, texture, or pattern around the edge of a decorative slab or panel. Borders frame the field, hide layout irregularities, and are often formed with separate pour strips.

A trial slab built before production work to confirm mix, color, texture, and finish meet the approved sample. It gives the owner and installer a shared reference for judging the finished work.

The proportions of cement, water, aggregate, and admixtures selected for a concrete pour. Decorative work usually calls for a consistent, low-slump mix so color and texture stay uniform from batch to batch.

The weight of water divided by the weight of cement in a mix. Higher ratios increase shrinkage, lower strength, and cause color variation, so decorative flatwork typically keeps it low and consistent.

A measure of how wet or workable a concrete mix is, found with a standard cone test. Consistent slump helps keep stamping and coloring uniform, and stiff mixes hold texture better.

Water that rises to the surface of freshly placed concrete as heavier solids settle. Excess bleed water weakens the surface, dilutes color hardeners, and delays finishing until it disappears.

The period during which fresh concrete stiffens enough to finish, stamp, or texture. Heat, wind, sun, and mix design all change set time, so timing of decorative steps must be adjusted to conditions.

Keeping concrete moist and at a suitable temperature after placement so cement continues to hydrate and gain strength. Proper curing protects color, reduces cracking, and improves surface durability.

Volume loss as concrete dries and hardens, which causes slabs to crack if restrained. Joint spacing, mix water content, and curing practices all influence how much shrinkage occurs.

Separation of a thin top layer from the concrete beneath, often appearing as blisters or peeling. It is commonly caused by finishing too early over bleed water or by trapping air under a dense troweled surface.

Sand, gravel, or crushed stone that makes up most of a concrete mix. Aggregate size, color, and hardness affect strength, workability, and the look of exposed-aggregate finishes.

A material added to a concrete mix to change its properties, such as retarders, accelerators, air entrainers, or water reducers. Admixtures can affect color and finishing timing and must be used consistently.

A sheet placed under a slab to stop moisture from the ground rising into the concrete. It reduces moisture-related floor problems but can slow surface drying, so finishing schedules must account for it.

The soil or prepared base beneath a slab. It must be compacted, uniform, and properly drained so the slab cures evenly and does not settle or crack unevenly.

The temporary molds and edge boards that hold fresh concrete in shape until it hardens. Sturdy, straight forms keep edges crisp and help decorative patterns align with the slab outline.

To scatter a dry material such as color hardener or release powder evenly over a concrete surface by hand or mechanical spreader. Even broadcasting is essential for uniform color.

A dry blend of cement, aggregate, and sometimes pigment broadcast onto fresh concrete and worked in with a float. It hardens and colors the surface and is a common base for stamped work.

The repeating geometric or natural design imprinted or scored into decorative concrete, such as ashlar slate, herringbone brick, or wood planks. Pattern choice drives stamp layout and joint planning.