Guide to Building a Small Cement Slab: A Comprehensive Guide for Beginners

Building a small cement slab is a fundamental skill in basic construction. This guide provides a detailed overview of the steps involved in creating a sturdy and durable cement slab, from the preparation of the area to the final curing process.

Stages of Slab Construction

Shuttering or Formwork Fixing

Shuttering, also known as formwork, is the initial stage where the structure’s framework is set up. This includes the installation of templates that will hold the concrete in place. The size and shapes of the shutter plates should match the dimensions of the required slab, and there should be no gaps between the plates to maintain the integrity of the slab. It is recommended to lubricate the shutter plates with a thin layer of oil to facilitate easier demolding.

Reinforcement Tying

Reinforcement is crucial for the tensile strength of the slab. The required diameter of the rebars (TMT) are cut, bent, and tied according to the design drawing. To maintain uniform cover, it is essential to place cover blocks beneath the steel bars. This ensures that the rebars are properly spaced and don’t come into direct contact with the concrete, which can reduce the overall strength of the slab.

Concreting

Concreting refers to the process of placing the concrete mix into the shuttered area. The concrete should be poured in layers, with each layer not exceeding a height of 1 meter. Compacting the concrete to the required height ensures a smooth and level surface. For rich mixes, leveling is often necessary to achieve the desired smoothness. Proper placement of concrete is crucial to avoid the distribution of the reinforcement.

Curing

Curing is a critical phase that follows immediately after the concrete has been poured. It involves retaining the moisture content in the concrete to facilitate the hydration process. Curing can be done by either sprinkling water or using wet gunny bags. This process should be carried out daily for up to 28 days after the casting to ensure the concrete reaches its full strength and durability.

Deshuttering

Deshuttering, or removing the forms, can be done once the concrete has gained sufficient strength to support its own weight. For reinforced slabs, it is generally recommended to leave the shuttering in place for 28 days, unless otherwise specified or if admixtures are used. Proper timing ensures that the slab is structurally sound and can be safely removed without compromising its integrity.

Additional Tips and Alternative Methods

When building a small cement slab, you can opt for a thinner slab depending on the weight it needs to support. Typically, a 4-inch slab is sufficient and will not crack under normal conditions. You can either dig out about 4 inches of soil to create a clean area for the slab, or use a 2x4 crib to level the ground before pouring the concrete.

For reinforcement, steel is the ideal choice, but it is essential to place it correctly. Ensure that the steel reinforcement is 3 inches from the ground and all edges. This placement will help distribute the load evenly and prevent cracking.

Finishing Touches

After the concrete has been poured and left to cure, it is time to add the finishing touches. Use a screed to level the concrete and identify and fill any low spots. A magnesium trowel is ideal for smoothing the surface. Continue to work the surface until it feels “stiff.” At this point, use a steel trowel to seal the surface. If necessary, add a small amount of water to the finish surface. This step is crucial for achieving a smooth and clean appearance.

Once the surface has been sealed, run a stiff bristled pushbroom to remove any excess material and ensure a clean edge. Remember, the concrete needs to cure for at least a day before removing the forms. Carefully wet the concrete daily for at least two weeks to aid the curing process and prevent cracking.

Final curing and maintenance are essential steps that ensure the longevity and reliability of your cement slab. By following these steps, you can build a small cement slab that is both strong and durable, providing a solid foundation for your projects.