A CBR tests measure the strength of soils and base materials in the field. This information is then used by pavement designers in their work. The field test is done by injecting a piston into the soil at the testing site and making a comparison of the load exerted on the piston to the depth of penetration into the ground. The penetration test is conducted in a load frame equipped with CBR test components. Usually, the load used to exert pressure on the piston during the test is heavy equipment such as a full dump truck.The CBR test can also be done in a lab. Here, soils with predetermined moisture contents are compacted into moulds. Preparations before the test include soaking and adding appendage weights to the moulded samples. The material in the moulded samples should be able to pass through a 19 mm IS sieve. There can be an allowance for bigger material by replacing it with the same amount of material that can pass through a 19 mm sieve but is still retained in a 4.75 mm IS sieve. However, this procedure will not be satisfactory if the soil particle size is mostly bigger than 19 mm. Finally, the sample can be compacted dynamically or statically.
The Florida Limestone Bearing Ratio test (LBR) was designed to assess limestone, and soil components characteristically found in Florida and run on similar methods and types of equipment like the ones in the laboratory CBR test. The elements of CBR equipment are ordered separately for tests performed under the Army Corps of Engineers (C.O.E.) guidelines. Here are the types of equipment used to do this test:
• Penetration piston. This is equipment is forced into the soil in the testing site to ascertain CBR values per COE and ASTM standards.
•Penetration Dial Gauge. This equipment measures the penetration and forces applied. A Dial Bridge and mounting accessories are used to fit the Dial Gauges during the measurement of penetration.
•CBR Surcharge Plate and Masses. These pieces of equipment are used to replicate confining loads from the base course and pavements.
•CBR Load Frames. These are customisable loading frames fitted with other apparatus to perform the CBR test. These frames can also be used with a variety of equipment for various soil test applications.
•Automatic Programmable Proctor. This is designed to compact Proctor and CBR samples, ensuring a seamlessly consistent compaction level, generating dependable and consistent test results. The microprocessor software enables the selection and performance of various compaction cycles automatically.
•Dual-Mass Dynamic Cone Penetrometer. This is equipment was developed by the Army Corps of Engineers (CEO), and Dynamic Cone Penetrometers (DCP) to provide a cost effective, competent test method for a swift determination of field CBR values of sub bases, sub grade and pavement bases. DCPs are mainly used to ascertain in-place soil tests.