Hey there! I'm a supplier of Drum Type Concrete Mixers, and today I wanna chat about what modifications are needed to mix lightweight concrete in these mixers.
First off, let's understand what lightweight concrete is. Lightweight concrete is made by incorporating lightweight aggregates, like expanded shale, clay, or slate. These aggregates are much lighter than normal aggregates, which gives the concrete its reduced density. It's great for applications where weight is a concern, like in high - rise buildings or precast elements.
Now, a standard drum type concrete mixer is designed to handle regular concrete. But when it comes to lightweight concrete, some tweaks are necessary.
Mixer Drum Design
The shape and size of the mixer drum play a crucial role. For lightweight concrete, a drum with a larger diameter and a lower aspect ratio (height to diameter) can be beneficial. A larger diameter allows for better movement of the lightweight aggregates. The lower aspect ratio ensures that the material doesn't get overly compacted at the bottom of the drum. This helps in achieving a more uniform mix.
Also, the internal fins of the drum need to be adjusted. In a regular mixer, the fins are designed to lift and tumble normal aggregates. Since lightweight aggregates are more fragile, the fins should have a smoother surface and a more rounded shape. This reduces the risk of breaking the aggregates during the mixing process.
Mixing Speed
The mixing speed is another important factor. Lightweight concrete requires a different mixing speed compared to regular concrete. If the speed is too high, the lightweight aggregates can break, which will affect the quality of the concrete. On the other hand, if the speed is too low, the mix may not be homogeneous.
As a general rule, a slower mixing speed is often recommended for lightweight concrete. You can start with a speed that's about 20 - 30% lower than the speed used for regular concrete and then adjust based on the results. You can observe the mix visually to see if the aggregates are being well - distributed and if there are any signs of breakage.
Loading Capacity
The loading capacity of the drum type concrete mixer also needs to be considered. Lightweight concrete has a lower density, so you might think you can load more of it into the mixer. However, overloading can still be a problem.
When mixing lightweight concrete, it's better to load the mixer to about 70 - 80% of its maximum capacity. This gives the material enough space to move around inside the drum, ensuring a more thorough mix. Overloading can lead to poor mixing and can put extra stress on the mixer's motor and other components.
Water Addition
Water addition is a critical step in mixing any type of concrete, and it's no different for lightweight concrete. But since lightweight aggregates can absorb more water than normal aggregates, you need to be more careful with the amount of water you add.
You can use a pre - wetting method for the lightweight aggregates. This involves soaking the aggregates in water for a certain period before adding them to the mixer. This helps to reduce the amount of water that the aggregates will absorb during the mixing process. Also, you may need to add water in multiple stages during the mixing to ensure that the concrete has the right consistency.
Power and Motor
The power of the mixer's motor is also a consideration. Mixing lightweight concrete may require less power than mixing regular concrete, but it still needs to be sufficient to handle the mixing process.
A motor with variable speed control can be very useful. This allows you to adjust the speed according to the requirements of the lightweight concrete mix. You can start with a lower speed for the initial mixing and then increase it slightly if needed to achieve a better mix.
Maintenance
Maintaining the drum type concrete mixer is essential, especially when mixing lightweight concrete. Since the lightweight aggregates can leave behind more residue compared to normal aggregates, regular cleaning of the drum is necessary.
You should clean the drum after each use to prevent the build - up of hardened concrete. This will also help to extend the life of the mixer. Additionally, check the internal components of the mixer regularly, such as the fins and the bearings, to ensure they are in good condition.
Compatibility with Admixtures
Lightweight concrete often uses admixtures to improve its properties, such as workability, strength, and durability. The drum type concrete mixer should be compatible with these admixtures.
Some admixtures can react with the materials inside the mixer, so it's important to choose a mixer that can handle the chemicals in the admixtures. You may need to do some testing to ensure that the mixer doesn't corrode or degrade when in contact with the admixtures.
If you're in the market for a drum type concrete mixer that can handle lightweight concrete, we've got some great options. Check out our Diesel Concrete Mixer and Drum Concrete Mixer. These mixers can be modified to meet your specific needs for mixing lightweight concrete.
We're here to help you find the perfect solution for your concrete mixing requirements. Whether you're a small construction company or a large - scale contractor, we can provide you with the right equipment and advice. If you're interested in learning more or want to discuss a potential purchase, don't hesitate to get in touch. We're ready to have a chat and help you make the best decision for your business.
References
- Neville, A. M. (1995). Properties of Concrete. Pearson Education.
- ACI Committee 211. (2014). Standard Practice for Selecting Proportions for Structural Lightweight Concrete (ACI 211.2 - 14). American Concrete Institute.