Laying concrete floors for various spaces such as patios, garages or driveways demands careful planning and execution. From surveying and preparation to pouring and finishing, each step plays a vital role in ensuring the durability and functionality of the concrete slab. This comprehensive guide will walk you through the process, highlighting essential techniques and considerations. At Tool Chest Hire we stock a range of tools and equipment for concreting projects and other DIY jobs.

Assessing Terrain

Surveying is a crucial preliminary step for ensuring the concrete slab is placed correctly and at the right elevation. Before commencing the concrete laying process, meticulous surveying and calculations are imperative to accurately determine the required volume of concrete, as well as the layout and grading for the slab. Surveying includes various practices, such as: 

• Levelling and Grading: Ensuring the ground is level and properly graded to the desired slope.
• Setting String Lines: String lines are set up to mark the edges and height of the slab.
• Transit or Laser Level: These tools help ensure the slab is at the correct height and slope.

Advanced tools like the Topcon RLH5A laser level can significantly streamline the surveying process. This laser level includes a self-levelling feature and boasts an impressive operating range of 800 metres.

Site Grading and Drainage

A gradient, also known as a slope or pitch, refers to the angle at which a surface rises or falls. Adding the correct gradient to the terrain ensures that water runs away from structures. In concrete slabs, a slight gradient is often necessary to prevent water pooling. 

Employing equipment such as the Kubota K008-3 0.8 tonne micro excavator facilitates precise earth movement. Using the blade at the front of the excavator, earth can be moved and graded accordingly to allow for proper drainage and a flat base. Additionally, excavation may be necessary for foundations, drainage ditches, or as part of the grading process. 
Compacting the earth with a compactor plate like the Fairport FPC400 ensures a solid base, while the addition of an optional geotextile fabric prevents fine particulates from compromising drainage.

Adding a Coarse Aggregate Sub Base

The layer beneath the concrete slab is known as a sub base. This layer provides support and acts as a foundation. A sub base is typically made of compacted gravel or crushed stone, also known as coarse aggregate. The incorporation of a coarse aggregate sub base is essential for structural integrity. It provides strength and helps reduce shrinkage.

Layering and compacting gravel not only enhance drainage but also distribute the load of the slab uniformly. Opting for larger sizes of gravel, preferably angular rocks, promotes interlocking and stability. It's important to note that pea gravel is usually not ideal for compaction since it lacks angularity and may not interlock effectively, compromising the stability of the base.
Consider thicker bases for areas prone to freeze/thaw cycles or heavy loads. To ensure a solid coarse aggregate base, pour layers of gravel and compact after each layer using a compactor plate. Add water to the gravel if it is dry to help with compaction.

Constructing Sturdy Forms

A construction form, also known as formwork or shuttering, is a temporary mould into which concrete is poured and shaped. Forms are made of wood, metal or plastic and define the shape and dimensions of the slab.

Sturdy forms are indispensable for containing the concrete during pouring and curing. Utilising tools such as the Makita HS6601 electric saw and a nail gun, wooden planks and stakes are assembled to create robust concrete moulds tailored to the structure's requirements. It's crucial to reinforce the forms adequately, as the weight of the concrete will exert pressure on the sides of the mould during pouring.

Rebar Reinforcement

Rebar is short for reinforcing bar. This is steel reinforcement used within concrete structures. It's placed within the formwork before pouring concrete to add strength and prevent cracking.

Reinforcing the concrete with rebar significantly enhances its strength and durability. Utilising a rebar bender such as the Ogura Industry HBB-525 makes the process easy, ensuring precise bending for optimal reinforcement. This stand-alone rebar bender with a built-in hydraulic pump effortlessly handles the toughest tasks, ensuring the structural integrity of the concrete base.

Pouring Concrete, Vibrating and Screeding

The concrete pouring stage demands precision, attention to detail and usually multiple people. Whether utilising concrete mixer trucks, or employing tools such as the Makita UT120 110v electric paddle mixer or a Belle cement mixer for on-site mixing, ensuring proper proportions and consistency is crucial. 

After pouring, there are a couple of processes which should be followed to ensure ideal consistency, these are vibrating and screeding.

• Concrete vibrating is the process of using a vibrating tool, such as a concrete vibrator, to remove air bubbles from freshly poured concrete. This ensures the concrete is compacted, reducing voids and improving strength.
• Screeding is the process of levelling freshly poured concrete. A screed board or a straight edge is used to remove excess concrete and create a smooth, level surface.

Tools such as shovels, screeds and vibrators such as the ENAR AVMU aid in levelling, compacting, and removing air bubbles, facilitating optimal concrete placement. Weighing only 5kg, the ENAR AVMU vibrator is easy to move around, allowing for efficient concrete compaction.

Furthermore, from this point on attention should be paid to environmental conditions such as sun, heat or cold, humidity and rain. Concrete will dry faster on a hot, sunny day with low humidity, so it is imperative to work fast in those conditions. If some areas of the concrete slab are shaded by surrounding structures or trees, those areas will dry more slowly.

Concrete Finishing

After screeding and when the concrete has dried enough, attention shifts to concrete finishing. The use of concrete floats helps redistribute the cement paste which has risen to the top, ensuring a smooth surface while minimising aggregate exposure.

Depending on preference, exposed aggregate or a brush or broom finish can be achieved, offering both aesthetic appeal and functional texture. Exposed aggregate is achieved by seeding or sprinkling pebbles, glass, or other objects evenly onto the concrete and using a concrete float to allow cement paste to cover them completely. As it dries, this top layer of concrete is washed off, leaving behind the exposed aggregate.

Strategic Control Joints Implementation

In anticipation of concrete shrinkage and cracking, control joints and expansion joints are strategically incorporated. Whether made before the concrete dries or cut into the solid slab, these joints guide the placement of cracks, minimising structural issues. Tools such as floor saws or cut-off saws, such as the Husqvarna FS400LV or Stihl TS410, facilitate precise joint creation. While floor saws are preferable, cut-off saws like the Stihl TS410 may be necessary for confined spaces where floor saws cannot reach.

Ensuring Strength Through Proper Curing

Curing is the final step in ensuring the concrete slab's strength and durability. Moist curing, involving frequent wetting of the surface, promotes slow moisture evaporation, preventing cracks and shrinkage. This method, practised over the first seven days post-pouring, contributes to a resilient and long-lasting concrete floor.

Laying concrete floors for outdoor spaces is a meticulous process that requires attention to detail at every stage. By following the outlined process and utilising the recommended tools and techniques, you can achieve durable and functional concrete floors for patios, garages or driveways that stand the test of time.

Why Choose Tool Chest Hire for Concrete Equipment Hire?

Based in Hammersmith, Tool Chest Hire offers a range of cement mixers and concrete and compaction equipment available for hire at competitive prices. Feel free to look through our inventory, or get in touch with us on 020 8748 7912. Our friendly team is always happy to take your call.