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What Is Concrete Topping?

High-tensile concrete is used to create concrete topping, which is a dense, abrasion-resistant surface that is put over an old, worn-out concrete surface. Its foundation is deeper and stronger concrete.

Concrete topping slab is an overlay designed to provide a dense, abrasion-resistant, and a finished concrete topper floor surface for multiple purposes such as providing a wearing course to support traffic loads in parking facilities and bus terminals, providing a level surface for interior floors .

Types of Concrete Topping

Two types of concrete topping slabs are:

1. Unbonded Topping Slab

The topping slab is not bonded to the sub concrete slab in this system. The final floor height may be affected by the thickness of the unbonded topping, which may also conflict with other service needs like doorway clearances.

Repairing base slab fractures may eventually allow them to reflect through a partially bonded overlay. Using thicker overlays can decrease reflective cracking. Also Read: floating slab

2. Bonded Topping Slab

The topping is bonded to the supporting concrete slab in a bonded system. It is utilised for heavy-duty slabs in industrial applications exposed to high traffic loads and impact as well as light-duty slabs in commercial applications.

The base slab should have an uneven, open-pore finish and be free of any materials that can hinder the binding between the topping and the base slab. The topping can be applied either before or after the underlying concrete slab has hardened. Also Read: Garage Door Pricing

Topping Slab Strength and Specifications

The strength of the concrete for bonded and unbonded concrete topping slabs depends on the function of the slab; for light duty, the strength is 30 MPa, for medium duty, 40 MPa, and for heavy load, 50 MPa.

The topping should be made of concrete with a maximum slump of 75 mm. A water-reducing admixture or a high-range water-reducing admixture should be used to augment the slump if low w/c is being used. Also Read: Oblique Sketching

Working Procedure of Concrete Topping

Before putting concrete on top of existing concrete, a preliminary examination is required. The top layer of concrete must be solid and stable. The fissures in the existing concrete are not covered by the topping concrete, thus they will eventually show in the topping concrete as well. To guarantee that the new concrete adheres to the old concrete, the base must be sturdy. Fragile concrete should not be used.

This step is important to guarantee that the old and new concrete stick to one another while pouring top concrete. The topping slab must be laid on a flat, spotless, dust-free concrete surface. Before installing the slab, the concrete topping must be fully removed. Also Read: Hip Valley Roof

The coarse aggregate must be evident when a smooth finish is applied to the base concrete via mechanical scabbing or scarification. Loose debris, filth, and dust should all be removed with a vacuum cleaner.

It's important to pick the correct time to prepare the base concrete. In order to avoid contamination and the buildup of dirt, you should prepare the base a day before setting the top slab for best results. Also Read: Contours Lines

Before pouring the topping concrete, it is crucial to ascertain the type of existing slab. After adding a tiny amount of water to the base slab, the rate of water absorption should be measured.

Before pouring the topping concrete, it's crucial to drain the water from the slab and let it sit wet for at least four hours. Once installed in the base, wet concrete takes water from the base slab, leaving dry concrete above it water-deficient. If there are no signs of water absorption, the topping concrete can be laid as usual. The typical thickness of a topping slab is between 50 and 100 mm. Steel reinforcement is offered in accordance with the thickness and specifications of the slab. Also Read: Metal Door

To provide optimum strength, maximum resistance to surface abrasion, and minimal impermeability, concrete must be well cured. Cracks brought on the drying shrinkage are or reduced by curing.

Cure also reduces the impact of differential shrinkage and curling by postponing the impacts of differential drying until the concrete can withstand them. After the curing is finished, at least seven days must occur. Also Read: How to Make Floor Tile Shine