Trials were carried out to investigate the strength of subgrade needed to allow rolled asphalt and dense coated macadam roadbases to be laid satisfactorily without a sub-base. Having established that a roadbase could be laid on a relatively weak foundation test pavements were constructed to enable the performance of conventional and full-depth pavements to be compared through the measurement of stress, strain and pavement deflection under load. Stress, strain and deflection calculated from linear elastic theory were not in good agreement with the measured values but theory indicated the same sensitivity of stress and strain to changes of asphalt thickness and dynamic modulus. It was therefore concluded that theory could be used to produce tentative designs by comparison with conventional designs. However, extensive road trials would be necessary to confirm the suitability of these theoretical designs and examine the practical problems of trafficking weak subgrades and compacting the lower pavement layers under difficult site conditions in wet weather. (Author/publisher)
Abstract