HOW TO POUR THE PERFECT CONCRETE SLAB10 Sep 2019, Posted by Concrete Facts in
Incorrectly pouring concrete can lead to significant problems down the road, including bug holes, cold joints, and honey combing. These problems commonly occur when using shoring equipment, but they can be mitigated by use of a concrete vibrator. This machine consolidates concrete and refines the pouring process. If you’re using Symons forms, keep reading to learn some essential tips for pouring the perfect concrete slab.
Make Use of Good Planning Practices
All the vibration in the world won’t make a difference if the concrete isn’t poured correctly. Here are some best practices to keep in mind before you begin:
• Have backup systems in place for every part of the job, including extra concrete vibrators and tools.
• Draft a carefully laid-out plan to avoid hiccups and mistakes during the job.
• Ensure that the mixing of the concrete is correct by using super plasticizer or water reducer to increase the slump of the mix.
• When placing concrete, keep in mind that rebar tends to obstruct the pour, creating air pockets and sifting.
• Use elephant trunks or placing equipment to reduce segregation.
These are just a few to get you started but use your best judgment according to your project.
Essential Vibrator Tips
Vertical Motion Only
Keep in mind that concrete vibrators should only be moved vertically. If they are moved from side to side, they can create uneven mixtures of aggregate and concrete. A horizontal motion tends to tangle the vibrator in the rebar. This can lead to flow lines and discoloration.
Timing is Key
You need to slowly let down the vibrator into poured concrete, allowing the weight of the vibrator to carry it to the bottom of the pour. Let the vibrator sit at the bottom for approximately 15 seconds, before removing it.
Vibrators work different amounts of the poured concrete, depending on the strength of the tool, which is measured in the circle of concrete affected by the vibration. These circles must overlap so that the concrete is properly vibrated.
Pay Attention to Spacing
Make sure to space out vibrator insertions closely together so that no concrete is missed. Under-vibration and over-vibration are common problems when pouring concrete. However, when in doubt, it’s safer to work on it a bit more, as under doing the job is a more significant problem. This reduces the chances of holes and honeycombing.
Using Machinery Alongside Concrete Forms
Extra care while using the vibrator near formwork is essential. Vibrators can damage formwork, which can be mirrored on the surface of hardened concrete. This damage is obvious when the forms are removed.
To avoid this, take care to not get close to the formwork while pouring. Concrete sets up in about an hour, a time during which a cold joint can be formed, weakening the overall structure. Be sure to vibrate every 15 minutes to prevent concrete from setting quickly.
When using the correct vibration techniques, paired with the right equipment, you can successfully form a strong structure that can efficiently bare a heavy load. As you consider equipment or concrete form rental for your next construction project, partner with Forming America.
Our extensive line of concrete forming equipment enables you to have what you need for the job. We ensure the highest quality rental equipment, so contractors have confidence every time they do business with us. Contact Forming America and partner with us to make that your next project is a success!