In pavement engineering, there is a need for improved methods of characterisation of materials. This would contribute to improved mix design, pavement design and quality control of the materials. In particular, granular and bitumen stabilised materials (BSMs) need for more reliable testing procedures than CBR, UCS and ITS tests for the characterisation and QA/QC (with bitumen and emulsion binders, has long been recognised by the roads industry. Granular materials and BSMs incorporating either foamed bitumen or emulsion can be viewed in the same light because of similarities in their behaviour i.e. stress dependency and shear resistance.

Triaxial testing for the evaluation of shear parameters is widely recognised as a reliable method of measuring the critical performance properties of granular and bitumen stabilised materials. However, the triaxial test in its current state as a research test has little chance of extensive use by practitioners and commercial laboratories, because of complexity, cost and time issues. Major adaptations to the research triaxial test are necessary, therefore, if such a useful test can have a chance of being accepted by road practitioners.

A study was carried out to investigate possibilities of developing a simple, economical, reliable and robust test for characterizing granular and bitumen stabilized materials, with a link to performance. This is achieved through innovative design and manufacture of a prototype triaxial cell capable of accommodating 150 mm diameter by 300 mm deep specimens. Ideas were developed based on some existing test apparatus such as the Texas Triaxial. The cell that has been developed is simpler than the research (geotechnical) triaxial cell and the operational protocols have been streamlined, thereby reducing the time and steps required in assembling specimens and testing them. A simple triaxial cell has been designed, comprising of a steel casing with a latex tube inside, making a less sophisticated test configuration, which eliminates the need for the use of O-rings, membrane and tie rods.

This paper provides details of the cell that has been design and monotonic triaxial tests that have been conducted using the simple triaxial cell. Results from the simple triaxial have been correlated with parallel test results from the research (geotechnical) triaxial apparatus. Explanations are provided as to the theory for processing of results to provide permanent deformation calculations as a result of repeated loading applied to the material.