1.1 Definition:

The work in this section should be designated as Exposed Aggregate. It includes all labor, material, equipment and transportation required to complete the item.

1.2 Description:

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 texture.

 1.3Related Work:

This 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.

 1.4 Quality Assurance:

The Contractor shall provide a job-site sample to be approved by the Architect prior to start of construction, (Optional)

 2.  PRODUCTS & MATERIALS:

 Concrete 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 permitted.

 ·       Water used for the mix should be clean potable water.

·       A colored powder, color………………………………………………….…….

·       The aggregates size …….……..…….mm, color. ……………..……………….

·       Acrylic Sealer ……………………………………………………….…………

 3. EXECUTION:

INSTALLATION PROCEDURE:

The area to receive exposed aggregate finish shall be treated as follows:

·     Sub-grade    preparation required as for any concrete slab on grade.

·     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 concrete.

·     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 method.

·     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 methods: -

-       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.

Glossary:

·       This Specification applies to Pave Crete 700

·       Aggregate where mentioned should be either Granite Granular or Marble Chips or Crushed Fractured Stone.

·       Colored powder is Pave Crete 200.

Acrylic Sealer is A-Z Super Sealer.