If you’re in the process of planning a new commercial or residential build, you will likely have already consulted a geotechnical team. Many regions in Australia require specific environmental tests and assessments to be conducted before the necessary permits can be issued.
For the most part, many of the required assessments form part of the soil testing Melbourne geotechnical engineers offer. A soil testing package typically comprises various tests, inspections, and assessments. One of the common tests to be aware of is the CBR test. This post explores what you need to know about this test as you schedule your geotechnical assessments.
All You Need to Know About CBR
The acronym CBR stands for California Bearing Ratio and is typically used to evaluate and assess the strength and durability of subgrade materials and soil needed to build the following:
- Roads
- Airstrips
- Pavements
- Parking areas
- Walkways
This test is conducted in accordance with guidelines detailed in Australian Standard AS 1289.6.1.1. We’ve compiled a list of crucial pointers that will help you understand what this type of soil test is all about.
- Understand How CBR Testing are Performed in Australia
Soil testing is an umbrella term that refers to a wide range of inspections and assessments that need to be done to establish the various characteristics are done. These tests can be done to determine how well the soil will hold the heavy weight of structures and also how effective soil drainage will be.
Some soil tests are done in the field while others involve collecting samples and then analysing these in a laboratory. Here’s what you need to know about these tests:
- Field testing: Also referred to as in-situ testing, CBR testing values are established by performing the Dynamic Cone Penetrator (DCP) test or the Plate Load Test (PLT). The results of these tests are then compared to the standard CBR value to assess how compatible your property is.
- Laboratory testing: Various soil samples are collected from the site and then prepared in a NATA-accredited laboratory. The collected soil samples are remoulded and compacted to a specifically determined moisture content and density. The sample is then soaked in water for about four days to simulate potential adverse moisture conditions such as flooding. The bearing capacity is then tested and evaluated. This will give your engineer a better idea of how strong the soil is and how likely it is to safely hold up in all types of weather and environmental conditions.
- Understand the Key Benefits of CBR Testing
Since CBR testing is specifically done during the planning,
design, and construction phases of projects involving pavements and roads, these results are crucial to determine how the ground will hold up under traffic loads. There are several benefits to having this test done, as listed below:
- Determines pavement thickness: The number one reason to determine the CBR value of your property is to determine how thick the surrounding pavements need to be. This means determining how much subgrade, subbase, and base course needs to be added during the build process to be able to withstand high volumes of traffic, even under strong weather conditions.
- Ensures structural integrity: The CBR test also assesses whether the underlying ground is stable and strong enough to support the types of structures and roadworks. This will effectively minimise the risk of premature failure, such as cracks, rutting, or settlement.
- Maintains compliance standards: Comprehensive CBR testing also ensures that your build, no matter how big or small, meets Australian building regulations and standards. This not only ensures that your build is safe but also prevents potential project delays and legal issues.
- Crucial for material selection: CBR test results are also crucial for your engineering team to determine the best materials for the required structure type. This ensures that material use is optimised, which in turn prevents over-design, such as using overly thick layers of expensive materials. Doing this reduces waste, costs and harm to the environment. On the flip side, it allows engineers to opt for stronger, more durable materials to make a weaker area strong enough to withstand weather and traffic conditions.
- Assesses moisture variations: Samples sent to the laboratory are soaked in water for at least four days at a time. This helps engineers determine how stable your structures will be during high rainfall or environmental conditions. This not only extends the life of your infrastructure but also reduces the likelihood of landslides and sinkholes. Weaker soils can be reinforced to maintain strength and durability in the worst weather conditions.
Final Thoughts
CBR testing is a crucial aspect of any build and is especially important when you’re planning roads, walkways, parking areas, and pavements in or around your building area. In addition to ensuring that your build is structurally safe, you’ll also be reducing the likelihood of fines and delays during the building process. Speak to your local geotechnical team for the types of soil tests and CBR assessments needed for your specific project.
