Visual Soil CBR Identification in the Field

Soil CBR identification. To determine the CBR of a soil precisely, tests must be carried out in accordance with SNI 1738:2011 using a field CBR apparatus or a DCP (Dynamic Cone Penetrometer).

This requires certified specialists to perform the CBR test, interpret and process the data, and make recommendations based on the results. For non-specialists, however, CBR can also be identified visually.

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Dealing with expansive soil

1. Very soft soil (CBR < 0.4%) can be identified by several visual parameters
2. The soil squeezes out between your fingers when squeezed
3. A person standing on this soil sinks > 7.5 cm

• Soft soil (CBR 0.4%- 0.8%) can be identified by several visual parameters
• The soil deforms under light finger pressure
• A person standing on this soil sinks 5.0- 7.5 cm

• Medium soil (CBR 0.8% – 1.6%) can be identified by several visual parameters
• The soil deforms under strong finger pressure
• A person standing on this soil sinks 2.5 cm

• Stiff soil (CBR 1.6% – 3.2%) can be identified by several visual parameters
• The soil indents deeply when pressed with a thumb
• A passing pickup truck leaves ruts of 13-25 mm

• Very stiff soil (CBR 3.2% – 6.4%) can be identified by several visual parameters
• The soil starts to indent when pressed with a thumb
• A loaded dump truck leaves ruts of 25-75 mm

• Hard soil (CBR > 6.4%) can be identified by several visual parameters
• The soil is hard to indent with a thumb
• A loaded dump truck leaves no ruts