A guide to concrete placement

Placing concrete is a crucial stage for contractors in Zimbabwe, as it directly affects the structural integrity and visual appeal of a building. While the correct type and mix of concrete plays a major role in the quality of the structure, there are many steps to follow after placement that can improve your results drastically.

Concrete mixtures with different strengths, workability, and particle sizes are required for different uses. Knowing these specifications will guarantee that the concrete will work as planned, with the required strength and desired finish. 

Whether you’re laying a load-bearing concrete floor for a warehouse or creating the foundations for a wide structure, this guide will help you choose the right Husqvarna machinery and pair it with the correct techniques for maximum strength and quality. 

Concrete vibration immediately after placement

The work begins as soon as the concrete is poured. Vibration creates a sturdy and long-lasting base, as well as ensuring that the mixture flows evenly over reinforcement bars and into all corners of the formwork. Vibrating fresh concrete also releases trapped air and helps to form a dense block for added strength. Air bubbles cause honeycombing and cavities, which can erode the concrete over time. 

Follow the concrete as it’s being poured with the vibratory poker and only stop vibrating when the surface becomes shiny or if a large bubble pops up near the poker needle. Remember that over-vibrating can also be detrimental to the strength, so keep an eye on your progress. Apply the poker needle vertically (at an angle of 90 degrees) into the wet concrete for the best results, and move the needle a distance of twice its diameter each time you poke the mixture.

Choosing the right type of vibratory poker size is an important decision. The diameter of the needle should be suitable for the concrete’s thickness and the spacing between rebars. Larger diameter pokers work better on thicker portions, whereas smaller diameter pokers work well on thin slabs and tight spaces. 

Before you start vibrating, you may want to coat the hose with a shutter plate oil to help prevent concrete from sticking to the rubberised hose. Be sure to have a backup power supply ready, as stopping the vibration procedure halfway through could give the concrete time to cure slightly and make it impossible to dip the poker needle properly.

A Husqvarna Smart Poker is ideal for cement columns, beams, walls, floors, bridges, tunnels, foundations, car parks, dams, pre-cast forms and slabs. These high-frequency electric pokers offer reliable performance and operator comfort. They have an intelligent, integrated frequency converter with LED lights to show you the status of the poker.

Concrete levelling and surfacing

Once concrete has been poured and vibrated, the next step is levelling. The tools and techniques used will depend on the kind of surface required. Screening is an important step for rough surfaces, which are often used as a foundation for other flooring materials. Screening is the process of levelling the surface as soon as it is poured using a screed or straightedge. 

Trowelling is required for smoother finishes, which are needed for polished concrete floors or areas that will be in direct sunlight. Trowels are used to produce a dense, smooth surface. Power trowels make this process easier and faster, simplifying the process of levelling expansive areas. Remember to start slowly, as freshly poured concrete is fragile; you can increase the speed of the trowel once the mixture has started to cure.

For the first one to three passes, use floating blades. If you need a smooth surface, use finishing blades for the rest of the passes. Steel and carbon blades are flexible and last longer, but they can affect the colour of the concrete, so if colour is important, use plastic blades.

Cutting expansion gaps in the floor

Expansion gaps or control joints allow the slabs to expand and compress under temperature variations without cracking. Large concrete surfaces need these gaps at regular intervals, and they allow the stresses to be released in a controlled way. It is vital to cut these joints at the right time; they must be cut late enough to allow the surface to sustain the weight of the cutting tools without being damaged, yet early enough to prevent cracking. 

Husqvarna offers several floor saws which are perfect for cutting expansion gaps. These machines are designed to work on green concrete (semi-cured), so contractors can start cutting the expansion gaps earlier. This creates precise, clean joints and reduces the possibility of random cracking. 

Work faster by determining the layout of the cuts in advance and drawing guidelines with a string and chalk on the green concrete. Be sure to use a Husqvarna diamond cutting blade that is designed for use on freshly poured surfaces, otherwise, the blade will clog up and become ineffective. The minimum depth of the expansion gap should be one-eighth of the slab’s thickness and no less than 25mm deep.

Cutting Edge is the supplier of Husqvarna construction equipment in Zimbabwe, and we provide a range of tools for each step of the concrete placing process, including vibration, surface finishing and joint cutting. Husqvarna’s centuries-long heritage is built upon innovation, reliability, and user-centric design. These construction machines are designed to endure the harsh conditions of construction sites. 

Contractors in Zimbabwe can rest assured that they can accomplish excellent concrete placements and guarantee the strength, longevity, and visual appeal of their projects by using Husqvarna equipment from Cutting Edge. To find out more about our range of construction machinery, please contact us today.

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Cutting Edge is the leading supplier of Husqvarna, GARDENA and Hunter products in Zimbabwe. We bring you the best tools in the business with world-class service and after sales care. Follow us on Facebook and Instagram for the latest news and product offerings from our brands.