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What is Sub Base?

In highway engineering and pavement construction, there are typically six layers which go into forming the pavement surface.

  • Fine-grained Sand
  • Pavers
  • Paver Base
  • Base Course
  • Sub Base
  • Subgrade

Sub Base is an aggregate layer which is located between the subgrade and base course layers and will be made of either unbound granular or cement-bound materials. The Sub Base layer is often considered one of the most important, typically acting as the main load-bearing layer of pavement which disperses the pavements load onto the Subgrade below.

While sub base is often selectively used on pavements designed exclusively for foot traffic, it is a necessary component for any surface used by vehicles or any other load bearing objects.

When it comes to Sub Base, the quality of materials is vital to the project given the effects it has on the useful life of finished pavement. A good quality sub base will often outlive the pavement’s surface, meaning once scraped off and the sub base is examined, a new surface layer can be applied without actually replacing the sub base.

What are the different types of Sub Base?

While Sub Base has the same application across most residential and commercial projects, not all Sub Base is equal. There are many different types of materials used to construct a Sub Base which are dependent on the inherent load-dispersion and drainage capabilities needed. Typically there are two types of material:

Unbound Granular Material

Unbound granular materials are aggregates which are not bonded or adhered when laid and compacted, but rather remain loose. This form of sub base relies heavily on the natural conforment of materials and can be loosened and removed with ease.

When talking about unbound granular material you will commonly hear about different classifications - all suitable for different projects. The classifications of these materials are:

  • DTp Type 1
  • DTp Type 2
  • DTp Type 3

Cement Bound Material

Cement bound material is also commonly referred to as a hydraulically bound sub base. These materials are bonded together through a binder, usually made of Bitumen or Cement and are consequently more difficult to remove or loosen when compared to its unbound granular counterpart. There are typically three classes of cement bound material including:

  • CBGM A
  • CBGM B
  • CBGM C

What Sub Base to use?

sub base services

Some of the most commonly asked questions we receive are about sub base, more importantly, which sub base to use. From “What Sub Base for a Driveway?” and “What Sub Base for a Patio?”, to What Sub Base is best suited for roads?” We have heard it all. While Sub Base can be generalised, it is best to seek professional assistance or advice with any project you are unsure about.

Typically across smaller scale projects including patios and driveways, an unbound granular material can be utilised, however, when undertaking commercial or large scale developments, cement bound sub base should be used.

If you are unsure which type or classification of sub base you require, be sure to contact a professional. You can contact our quarry supply professionals on 1300 291 130.

Sub Base Supply Services

As one of Australia's leading Sub Base suppliers, you can always be sure you're getting the absolute best in quality and customer service when you work with the team at Boodle's Concrete. After more than 50 years in the construction and earthwork industries, we know the importance of relationships in every aspect of our business. That experience also means we can share our relationship with you, to bring the absolute best materials to your next project.

Boodle’s Concrete services can supply Sub Base all over Queensland. We are based in Chinchilla but are able to supply the surrounding areas, including Brisbane, Toowoomba, Sunshine Coast, Gold Coast, Biddenden, Gayndah, Miles, Roma, Charleville, Biloela, Emerald, Rockhampton, Gladstone and Bundaberg.

To find out more about our quarry supply services or to place an order for Sub Base or other Quarry Supplies, contact us directly on 1300 291 130.



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