The work in this section should be designated
as Exposed Aggregate. It includes all labor, material,
equipment and transportation required to complete the item.
Concrete floors with exposed aggregate are
concrete slabs cast on job site and while it is still in the
plastic condition, the surface is treated with a dry-shake mix
containing granite granules or fractured stone aggregates or
marble chips and colored powder, it is floated and trowel led
either manually or mechanically (power machine). The
aggregates are exposed by different techniques to the required
system of paving includes the following: -
Sub-grade preparation and compaction to required level.
Provide shuttering and reinforcement where needed.
Supply of concrete in specified slab thickness.
Supply and broadcast the color powder and aggregates.
Toweling and floating of concrete surface.
Expose of aggregates.
Provide contraction joints by saw cutting.
Supply and apply two coats of sealer.
The Contractor shall provide a job-site sample
to be approved by the Architect prior to start of
PRODUCTS & MATERIALS:
Mix Design: -
The concrete shall have minimum compressive
strength of: --
4,000 psi in severe freeze thaw areas.
3,500 psi in moderate freeze-thaw areas.
3,000 psi in non freeze areas.
Portland cement shall conform to ASTM C150.
TYPE I, II or V, depending on soil conditions. Aggregates
shall conform to ASTM C33. Mixing water shall be fresh, clean
and potable. In freeze thaw areas only, an air entraining
agent complying with ASTM C260 shall be used to achieve an
entrained air content for the particular concrete mix used
in accordance with the published recommendation of the
Portland Cement Association and the American Concrete
Institute. No admixtures containing calcium chloride are
Water used for the mix should be clean potable water.
A colored powder, color
The aggregates size
The area to receive exposed aggregate finish shall be treated
Sub-grade preparation required as for any concrete slab on
The formwork shall be installed and the slab thickness shall
be the same thickness as would be required for any ordinary
concrete slab exposed to the same conditions and use.
Structurally, the concrete is most often a monolithic slab on
grade with a thickness 10 cm or greater.
Provide reinforcement when specified.
It is recommended that Polypropylene Fiber be added to the
concrete mix at the dosage of 0.750 kg. Per cubic meter of
Control joints and / or expansion joints shall be provided in
accordance with the plans.
The concrete shall be placed and screeded to the finished
grade and floated to a uniform surface in the standard
Waite for the bleed water and shine to disappear from the
surface before applying the colored powder, and then float the
surface mixing the color powder with the concrete surface.
Then the aggregates shall be applied evenly to the plastic
surface by the dry-shake method using 7.5 kg. Per square
meter. It shall be applied in three or more shakes, floated
after each and trowelled only after the final shake.
Toweling the finished surface using power floating machines is
preferable to manual one.
Instead of separate dry-shake of color powder
and aggregate, a mix of both in the dry-shake method is
recommended if the aggregate size is less than 4mm.
Exposure of aggregates is made by one of the following
Using soft brush with water spary before the concrete skin on
the surface dries.
Pressured water, few hours after finishing.
Acid wash after the concrete has cured.
Surface retarder mist spray while the concrete is still green
and wash the next day.
Sandblasting, preferable to previous ones since it produces
homogenous texture and finish, and it is mush faster.
Provide enough contraction joints by saw cutting the concrete
slab to a depth of 2.5cm (25% of concrete slab thickness) and
at no more than 36 times the slab thickness.
As soon as the surface dries, it shall receive first coat of
sealer, the second coat being the next day.
This Specification applies to
Aggregate where mentioned should be either
Granite Granular or Marble Chips or Crushed Fractured Stone.
Colored powder is Pave
Acrylic Sealer is A-Z Super Sealer.