| dc.description.abstract | Research workers and practitioners in the field of Civil Engineering recognize with disappointment, that both highway and airfield pavements are not analyzed and designed with purely scientific approaches. This state of affairs exists largely because the determination of the stress-strain behaviour and failure criteria, of all the possible modes of failure of pavement materials has not been developed fully. The commonly used pavement materials include bituminous bound, cement bound, unbound aggregates inclusive of cohesionless and cohesive sub grade soils. All these materials must be characterized under the possible in-service loading and environmental conditions, if at all analytical design procedures of pavements are to be
developed.
The determination of the fundamental properties of materials for analytical design of engineering technical systems is best termed physical characterization. Currently, the commonly used pavement materials evaluation techniques are essentially empirical in nature. These empirical methods of materials evaluation are collectively referred to as technological characterization. As such there is insufficient understanding of the fundamental behaviour response of pavement construction materials, under varied traffic loading and environmental conditions.
This suggests that the current conventional pavement design procedures and materials specifications do not take into account the actual materials fundamental behaviour response to all in-service loading conditions. As such it is not possible to estimate the various resistances or strengths of different pavement materials and pavement structural elements to varied load effects. Hence, it becomes increasingly difficult to obtain design criteria against the possible modes of materials failure, and therefore pavement functional and structural failures.
Therefore, it cannot be overemphasized that there is a necessity to continuously replace the conventional design procedures, which are largely technological or empirical in nature, with design procedures based at least partly, if not wholly, on the fundamental properties of pavement materials. Consequently economical and durable technical systems can be designed from the local materials under the prevailing climatic conditions.
Generally, it is recognized that technological methods of materials and pavement design are very well entrenched in the practice of pavement engineering. However, if conversion from technological to physical pavement materials characteristics is possible by means of constitutive laws, then it would mean that technologically designed materials can be characterized in either way, i.e. technologically or fundamentally, and then converted to the other.
Such an approach would be appropriate in handling the physical characterization of pavement materials whose current design procedures are largely technological. This indicates the need to develop constitutive | en_US |
