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Unbound Granular Materials

Unbound granular materials are commonly used in capping layer, sub-base and roadbase construction. The grading of unbound granular materials, established by wet sieve analysis, should be checked for compliance with the relevant specified grading envelope. The plasticity, mechanical strength, moisture content and density are important factors for acceptable in-service performance. A sampling rate of 1 sample per 500 tonnes is recommended for these materials.The level of compaction and moisture content of unbound granular materials during construction can be readily monitored using a nuclear density guage.


Highway Testing Laboratory Ltd. can sample, test and certify the quality of your unbound granular materials for use in road construction. A list of the tests which we perform are listed below:


Unbound Granular Material Tests:


Moisture Content

Plastic Limit

Specific Gravity

Density Tests

Ten Percent Fines Value (TFV)

Density/Moisture Content Relationship

California Bearing Ratio (CBR)

CBR/Density Relationship

Sand Replacement Test

Nuclear Density Gauge


The standard tests for assessing granular materials are performed in accordance with B.S. 1377 "Soils for Civil Engineering Purposes", B.S. 812 "Testing Aggregates" and the Department of the Environment "Specifications for Road Works".

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