Concrete Mixers: Subgrade and Subbase Explained



If you are going to be using your concrete mixers to create a concrete pathway, driveway, or slab at home, you are going to need to create a subgrade and a subbase. A subgrade and subbase are the layers beneath the concrete slab which provide strength and ensure longevity. We have answered the common questions around subgrades and subbases so that you can feel confident when you create your concrete project with your concrete mixer.




Why Do I Need to Know About a Subgrade and Subbase for a Home Concrete Projects?


Concrete projects at home are easy to do thanks to the portable concrete mixers available at B&S Commercial Power. With B&S Commercial Power concrete mixers, transforming your dirt driveway into a sleek concrete driveway or adding a patio to your granny flat is now something you can do without the extra expenses of a contractor.


You may feel that creating a concrete pathway or slab for your gazebo at home does not need a subgrade or subbase. But any concrete project is only as good as the foundation you create.


When a concrete slab cracks or fails, we often immediately assume there is a fault with either the quality of the concrete or the structure. While incorrectly mixed concrete or improperly structured concrete can result in fails, an inadequate subgrade and subbase can also cause problems for your concrete project down the line. A subgrade and subbase are therefore important for ensuring the strength and durability of your concrete project.


We take a look into the difference between a subgrade and subbase so that you can create a long-lasting concrete project that will be a point of pride in your home.


What is a Subgrade?


A subgrade is a tightly compacted, uniform surface. It is the first layer beneath your concrete slab and acts as the base for your project.


The thickness of your subgrade is dependent on the load it will need to bear. For example, a subgrade for your garden pathway will be less thick than a subgrade for a public road.


There are two types of material you can use for your subgrade. The first type of subgrade is to use existing bedrock, which is a solid rock surface that lies beneath the soil. Using bedrock is not often a subgrade option for projects such as a concrete pathway, home driveway, or slab, as the bedrock often lies too deep beneath the surface.


The second type of subgrade is composed of soil. The soil used can either be the existing soil at the project site, which is commonly referred to as native soil, or brought-in soil. The type of soil you use for your subgrade is important. You need to ensure that the soil you choose enables stability and drainage for your concrete project, and the type of project will require a different type of soil.


We have created a quick list of the different types of soils you can use for your subgrade.


  1. Clay.
  2. Silt.
  3. Moorum.
  4. Gravel




The subgrade needs to be tightly compacted to ensure that there is no future settling of the soil and that there is a uniform, dense base for the next layers. Compacting is critical for a subgrade as this ensures that the soil does not have pockets in which water can pool and affect the subgrade solidity. The compacting of the soil also increases the load-bearing capacity of the concrete slab and therefore ensures strength for your concrete project.




To compact your soil for your subgrade, you will need a compacting machine. For small concrete projects at home, you can use a single-plate compactor. B&S Commercial Power has a range of single-plate compactors that are perfectly suited to creating a subgrade for a concrete pathway, driveway, or slab at home. For larger projects, such as a road, you will need a drum compactor.


Once you have created your subgrade, the next step is to create your subbase for your concrete slab.


What is a Subbase?


The subbase is a layer of aggregates. The subbase lies on top of the subgrade and beneath the concrete base. As with the subgrade, the thickness of the subbase depends on the load-bearing needs of the concrete project.




There are a variety of aggregates you can choose from to create your subbase. You can use recycled materials such as crushed concrete, brick, or plastic aggregates, manufactured aggregates, various stones, and a granular fill. You need to ensure that the aggregate you choose is strong, durable, impermeable, and clean to ensure durability and load-bearing suitability.


The subbase can consist of either unbound aggregates or bound aggregates. You can combine your aggregates with coarse sand that acts as a binding agent. Alternatively, you can add a low quantity of cement to the aggregates to ensure that there is minimal movement of the aggregate. You can create your aggregate mixture of either aggregates and sand or aggregates and cement in your concrete mixers from B&S Commercial Power.


Subbases are important for your concrete project. We have created a list of the benefits of a subbase.


Strength: Concrete is already a strong material choice for a pathway, driveway, or slab at home. A subbase then provides additional strength, which will increase the durability of your concrete project.


Support: The subbase provides an additional layer of support to your concrete project by helping with the load-bearing qualities of your concrete project.


Drainage: Unless you have added selected additives to your concrete, your concrete will be permeable. If there are any fine cracks in your concrete, even more water will be able to seep in. Rather than allowing the water to be trapped under your concrete and causing further damage to your slab, pathway, or driveway, the subbase allows for better drainage. The drainage quality of the subbase, therefore, increases the longevity of your concrete project.


Protection of Subgrade: The subbase also acts as a layer of protection for the subgrade. The subbase limits damage or disruption of the solid subgrade when there is a heavy load on your concrete project.


Cost Reduction: To simply fill concrete on top of your subgrade would not only reduce the strength and longevity of your project, but would also increase the expense of your driveway, pathway, or slab. The subbase, therefore, reduces costs as it reduces the amount of concrete you need. You can also select inexpensive aggregates to reduce the costs of your subbase.


Once you have created your subbase, you are ready to pour your concrete for your concrete base.


Concrete Bases with Concrete Mixers:


This is the exciting part of your concrete project as it is when your concrete pathway, driveway, or slab starts to take shape! Before you start, you will need to acquire the correct quantity of cement and aggregates to make your concrete.


Various online concrete cubic metre calculators will help you work out the quantity you need. We recommend purchasing extra to make sure that you are not making a quick supply dash to the shops mid-way through your project!


For certain projects, you will need to add a reinforcement on top of the subbase to provide your concrete project with structure and additional strength. Steel bars are most commonly used as reinforcement for concrete slabs. Once your reinforcement is in place, you can mix your concrete to pour your concrete base.


When it comes to mixing your cement and aggregates, you have two options. You can choose to do the laborious, time-consuming option of mixing the concrete manually, or you can choose to use quick and efficient concrete mixers. Concrete mixers also reduce the risk of having imperfectly mixed concrete, which can cause all your hard work preparing the subgrade and subbase to go to waste.


Once your concrete is mixed, you can pour your concrete base and then allow the concrete to cure.


When it comes to creating perfectly mixed concrete for your concrete base, concrete mixers from B&S Commercial Power are the ideal choice for home concrete projects.




B&S Commercial Power Concrete Mixers:


B&S Commercial Power is a proud supplier of Baumax concrete mixers. Our concrete mixers are powerful and will provide you with perfectly mixed concrete for the concrete base of your driveway, slab, or pathway.


Our concrete mixers are available in different drum sizes to ensure that you can find the best concrete mixer for your home or commercial project needs. Here is a quick list of the concrete mixer drum sizes available at B&S Commercial Power.


  • Baumax BS360L Concrete Mixer with Baumax RX200 Keyway Engine.
  • Baumax 500L Concrete Mixer with Baumax RX200 Keyway Engine.
  • Baumax BS360L Concrete Mixer with Baumax RX200 2:1 Engine.


Our concrete mixers are available at a value that is suitable for either DIY projects at home or commercial use. We make sure no matter your budget for your concrete project, you can have access to a concrete mixer. Perfectly mixed concrete is the best way to make your concrete project a success, and we want to help your concrete project succeed.


If you are looking to purchase a concrete mixer for your home concrete project, get in touch with one of the friendly B&S Commercial Power advisors for assistance.


About B&S Commercial Power:


B&S Commercial Power is a Cape Town-based importer and manufacturer of power tools. We stock a wide supply of power tools to ensure that you are covered for every home or commercial project. From concrete mixers to brushcutters to compactors, B&S Commercial Power is your one-stop shop for your power tool needs.


At B&S Commercial Power, you will find only the best power tools created by world-leading brands. We only stock the best of the best so that you can trust that the quality, performance, and longevity of the power tools you purchase from B&S Commercial Power will be worth the investment.


We make sure that no matter where you are in Southern Africa, you have access to the high-quality power tools available at B&S Commercial Power. With our quick and reliable delivery service, we can supply your power tools to your home in Gauteng or your business in Swaziland.


Alongside our wide range of high-performance power tools, you also have access to the highly experienced B&S Commercial Power team. Our team has over a decade worth of experience when it comes to power tools and their uses, therefore we can provide you with the best advice and assistance for your power tool needs.


If you would like to increase your own experience and understanding of the power tools available at B&S Commercial Power, you can attend one of our regular training workshops held at our Cape Town facility. Ensuring that everyone has access to power tools and has the best understanding of how to use the power tools is our number one goal.




Create the perfect concrete pathway, driveway, or slab with concrete mixers from B&S Commercial Power and a solid subgrade and subbase.