Understanding Slabbing in Construction: Process, Types & Perks

Slabbing is one of the fundamental processes in construction in which a hard, smooth surface is built, often used as the base for roof decks, floors, ceilings, or outdoor conduits. Generally made of pre-cast concrete or other materials, the usual thickness of slabs is several inches plus, they are reinforced by columns, walls, beams, or grounds.

For instance, reinforced concrete slabbing is one of the most common kinds of slabbing, which incorporates steel reinforcement bars (rebars) for added strength and stability. Which kind of slab is to be used for a particular construction project depends on various factors, including the project type, the size of and weight of the infrastructure, environmental conditions, government protocols, etc.?

Slab Construction & Design: Knowing the Fundamentals

For designing slabs for the ground, there is a simple three-step process to follow:

1. Slab Selection
2. Slab Dimensions
3. Slabbing Reinforcement

All these operations demand facilitation for which the designer has to consider several factors including:

• Climatic Conditions

The ground soil is affected differently by varying degrees of moisture, which is why climatic conditions can make a major impact. For instance, you can expect severe expansion or shrinkage due to broad variations in the moisture content, depending on the soil’s reaction to it. Such a phenomenon can adversely affect the foundations and the superstructure.

If a drought hits right after high-water season, this can cause moisture underneath the slab perimetre to evaporate more swiftly than the soil under the slab’s centre. Moisture in the central location may persist for a long time due to the capillary action. If the ground undergoes high moisture content, this will create a totally different phenomenon. Either of these will shift the configurations and level of the ground below and damage the slab, developing cracks.

• Soil Conditions

Before starting any construction activity for the project, even before choosing the slab, a thorough inspection of the construction site has to be carried out and the first part of the process is categorising the soil type.

Construction contractors conduct soil tests to identify the type of soil such as, plastic, rock, lose, or organic soils, etc. The depth of layers is also measured to identify the right layer for setting up the foundations. Moreover, the moisture content of the soil is also checked. In case of soil contamination, contractors then may have to undertake quarries and refilling.

• Infrastructure Type

Considerations for residential construction differ immensely from that of commercial construction. For domestic settings, slabs on the ground separate the ground and the habitable place. Such properties usually have to deal with light loads and will not experience heavy machines or traffic. They also have to bear a part of the entire infrastructure’s freight, dispersed from the walls to the floors and foundations.

On the other hand, slabbing garden or patio paving slabs in your backyard will not require as much strong concrete slabs. For commercial properties, this function gets completely changes. They are much larger and heavier than residential properties with more traffic in the form of machines and people. Thus, construction contractors need to pick the right size and type of slabbing based on the type of infrastructure and its intended use.

Types of Designs for Slabs

There are over twenty types and designs of slabs available in the market, some of which have been discussed below:

1. One Way Slabs: These slabs cross and bend in one direction only but can be stronger than 2-way non-fortified slabs depending on the freight’s size and type.
2. Mud Slabs: Also known as rat slabs, this slab type is much thinner than grounded-bearing and suspended slabs. It is extremely economical, does not require any support, and can be used for slabbing gardens.
3. Two Way Slabs: Two-way slabs are surface members, having horizontal and vertical moment-resisting reinforcements. Being supported on all four sides, they can bear heavy weight and vibration.
4. Prefabricated Concrete Slabs: Prefabricated slabs are made off-site in extensive, thin sections, and then sent to the construction site when required. As they are built within a controlled environment, they yield more benefits. Workers apply a post-stressed or pre-stressed procedure to prepare them.
5. Unreinforced Slabs: Also known as plain paving slabs, these slabs have their whole weight to be endured by concrete as they are not reinforced. The flexural forte of the concrete needs to be higher than the freight to prevent cracks.
6. Ground Bearing Slabs: Also known as” slab-on-grade” or “on-ground” slabs, this slab type is utilised for residential and commercial floor building. It is built according to soil conditions and needs curing for gaining sufficient strength as it stays in contact with the ground soil and has to bear severe pressure. Ground-bearing slabs, also known as concrete floor slabs are poured directly onto the ground, serving as the foundation and floor for a structure.
7. Suspended Slabs: Suspended slabs come in different types, for instance, corrugated slabs, that are created by pouring concrete into corrugated steel trays, which amplifies its strength. Similarly, there are ribbed slabs that comprise small concrete (reinforced) T-beams linked to girders which are additionally supported by building columns. They provide strength in just one direction. Deeper, stronger, and heavier than ribbed slabs, waffle slabs also need sturdier foundations as they offer significantly high mechanical strength in both directions.

Precast Concrete Slabs: What are the Perks?

Precast concrete slabs are considered useful for construction projects due to a number of reasons:

• They have a high thermal resistance.
• They offer greater resilience to weather conditions.
• They can bear heavy compression and can show efficient performance against high tensile strengths.
• They require less labour on site, as all the construction works, i.e., the heavy lifting and casting, are done in the factory.
• They hardly develop cracks so you don’t have to worry about their maintenance as much.
• They can be designed in numerous sizes, shapes, and finishes to fulfill diverse architectural requirements.
• Being made from concrete, which is a durable material, slabs are robust and provide long-lasting walls and floors.
• The slabs radically decrease construction time due to precasting, making them ready to be installed once they arrive on site.

Constructing Slabs: Step-Wise Process

Here’s a brief look into the process of building slabs for construction projects:

• Site Preparation

In this first step of the slabs construction, a flat surface is required to create a tough and robust slab after the area is cleared of rubble, vegetation, and other hindrances. Generally, the ground is excavated and flattened. Then a compressed sub-base or foundation, usually made of sand or gravel, is laid to offer stability and allow efficient drainage.

• Preparing Formwork

Utilising metal or wood, formwork creates a mould for shaping the concrete slab and helps to hold the concrete in place during curing. The formwork needs to be firmly secured to avoid shifting during pouring that ensures its accurate alignment and dimensions.

• Placing Reinforcement

After the formwork has been constructed, you need to install reinforcements but before pouring the concrete. Reinforcements such as wire mesh or steel rebar are needed to be placed at the right depth for preventing cracking and improving tensile strength.

• Pouring Concrete

Next, a controlled ratio of water, cement, and aggregates is blended and prepared for the pour. As an alternative, a truck full of pre-mixed concrete is used on-site. A vibrator is used against the formwork to eradicate air pockets and ensure proper settling down of the concrete.

• Finishing the Surface

A trowel or screed is used to level the slab surface. You might need to apply finishing techniques such as polishing, stamping, or brushing to the concrete floor, depending on the project’s requirements.

• Curing the Concrete

Now, you need to keep the slab moist for preventing premature drying and cracking thus, allowing the slab to cure (i.e., harden) for maximum strength. Depending on the weather and mix, curing can take several days to weeks.

Get Slabbing Support for Your Construction Projects!

Slabbing is the foundation for construction projects when it comes to providing a staunch support. However, such a support through slabbing can only be guaranteed if done by professionals who understand the intricacies involved in this process, can come up with the right solutions, and possess skills and relevant equipment to materialise the given solution.

HEB Contractors LTD. is one such company undertaking construction projects for 15+ years and providing relevant solutions with its qualified civil engineers. So, if you want slabbing support for your projects then call us at 01344 444929 or email info@hebcontractors.co.uk and we’ll send our best masons for your project.