Pouring a concrete slab on a slope is a highly technical job. Under different working conditions, the concrete slope construction scheme is also different. For example, when the slope is small, the construction area is relatively small, there is no high requirement for concrete, and you only need to keep accurate formwork support to easily complete the work. However, when the surface area is relatively large (for example, concrete slabs of several hundred square meters), the small slope will be very difficult to control. There are also some concrete slopes with large slopes. In addition to selecting the correct concrete slump, preparation for a response should be done, and appropriate construction equipment should be used.
Below we will explain the precautions and best methods for pouring a sloped concrete slab.
How To Choose The Slump For Concrete Slope
The concrete slump is crucial for pouring sloped concrete slabs. If you use high-slump concrete, the concrete will be too fluid to hold the slope. However, if the concrete has a too low slump, it will make your work more difficult.
How To Test Slump?
The test method of slump: with a φ100mm upper mouth, φ200mm lower mouth, 300mm high horn shape slump bucket, filling concrete three times, each time after filling with a hammer along the barrel wall from the outside to the inside hit 25, after compaction, wipe flat. Then pull up the bucket, concrete because of its weight slump phenomenon, with bucket height (300mm) minus the height of the concrete peak after collapse, called slump. If the difference is 10mm, the slump is 10.
*The measurement standards of each country and even region are different. For specific measurement methods, please refer to the local concrete standards.
So, if a professional concrete supplier provides your concrete, you need to tell them your working conditions, and they will choose the right kind of concrete for you. If you want to know the specific data or mix the concrete yourself, you can refer to our suggestions below.
Slope: Less Than 10°
For some concrete slab works with a low slope (within 10°), you can use a concrete slump of more than 3 “. But there are small projects, like stairs and ramps for some homes and small terraces. High-slump concrete can also be used even if the slope is more than 10°. You need to set up the formwork and then use a hand screed to scrape the concrete flat. You can have good control of the slope.
Slope: 10° – 30°
For a concrete slope with a large slope (slope greater than 10° and less than 30°), the selection range of general slump is 2 “-3”.
For slopes over 30° and less than 45°, choose concrete with a drop of 1″-2″. Shotcrete or double forming can be used when gradients are greater than 45 degrees or even vertical (such as tunnel walls or guard slopes).
How To Pour Sloped Concrete
Home Ramps, Diy Concrete Slab
As we mentioned above, for some small (domestic) concrete projects. You need to set up the formwork and then use the hand tools to complete the slope.
*Mike Day Concrete has made a video explaining the construction method of a small concrete slope project in detail. You can fully grasp the process through below video.
Industrial Floors And Large Car Parks
For some large areas concrete slopes (small angle), such as some industrial floors or large car parking. These small slopes of the floor can be formworked many times fromwork and then scraped flat using a power screed. But this construction, the difficulty will be relatively large. Currently, the best way is to use a laser screed to automatically make these concrete slopes. In this way, you only need to set up the formwork at the edge of the working range once, and the concrete laser screed can automatically level according to the slope you set. This method can save a lot of manpower.
Laser Screed Slope Video
Concrete Slab With a Large Slope
In addition to the use of viscous concrete with a low slump (as mentioned above), it is also important to note that concrete levelling equipment with strong vibrations should not be used. Because too much vibration will make it difficult for concrete to hold down and cause downward flow. We recommend that you use a roller screed to level these concerts. In addition, you also need to consider whether the construction personnel on both sides of the construction can walk smoothly. You can use wood or scaffolding to set up a ladder for walking.
From our article, I’m sure you already know some about how to pour a concrete slab on a slope. We must pay attention to the concrete slump in constructing these concrete slopes. And the choice of the right tools is also very important. At the same time, the construction site supporting facilities must be prepared. This way, you can easily complete a sloped concrete slab.