The placement of concrete is a very important operation, which largely determines the success of a structure and its durability.

As such, Rockcrete staff take particular care when placing concrete and take into consideration all the technical and climatic parameters that need to be considered.

There are a number of different phases between the time when concrete leaves the mixer and the finished structure: transport, pouring into formwork or a mould, vibration, maturing, form removal and curing. Our staff are highly skilled in all phases of Concrete Placement and Finishing and we comply with the rules of, what we call, “good engineering practice”.

We facilitate and coordinate the concrete placement process to ensure the best possible result by managing the speed/height/flow ratio in order to avoid the danger of segregation and to provide rate of concreting that is as constant as possible.

On certain jobs, the concrete is placed in forms, and then consolidated. Consolidation compacts fresh concrete to mold it within the forms and around embedded items and reinforcement and to eliminate stone pockets, honeycomb, and entrapped air.

Vibration, either internal or external, is the most widely used method for consolidating concrete. When concrete is vibrated, the internal friction between the aggregate particles is temporarily destroyed and the concrete behaves like a liquid; it settles in the forms under the action of gravity and the large entrapped air voids rise more easily to the surface.

Concrete that will be visible, such as driveways, highways, or patios, often needs finishing. Slabs can be finished in many ways, depending on the intended service use.

Options include various colours and textures, such as exposed aggregate or a patterned-stamped surface. Some surfaces may require only strikeoff and screeding to proper contour and elevation, while for other surfaces a broomed, floated, or trowelled finish may be specified.

Screeding or strikeoff is the process of cutting off excess concrete to bring the top surface of the slab to proper grade. A straight edge is moved across the concrete with a sawing motion and advanced forward a short distance with each movement.

Bullfloating eliminates high and low spots and embeds large aggregate particles immediately after strikeoff. This looks like a long-handled straight edge pulled across the concrete.

Jointing is required to eliminate unsightly random cracks. Contraction joints are made with a hand groover or by inserting strips of plastic, wood, metal, or preformed joint material into the unhardened concrete. Sawcut joints can be made after the concrete is sufficiently hard or strong enough to prevent ravelling.

After jointing the concrete, it is floated with a wood or metal hand float or with a finishing machine using float blades. This embeds aggregate particles just beneath the surface; removes slight imperfections, humps, and voids, and compacts the mortar at the surface in preparation for additional finishing operations.

Where a smooth, hard, dense surface is desired, floating is followed by steel trowelling. Trowelling will only be done on a surface that has been floated. A slip-resistant surface can be produced by brooming before the concrete has thoroughly hardened, but it should be sufficiently hard to retain the scoring impression.

All this we do to the specification and satisfaction of the Builder’s requirements.