During the 1970s WES had conducted a review of lateritic gravels specifications, together with limited field surveys and laboratory testing, resulting in a tentative classification scheme for the use of lateritic gravels in military pavements. Whilst it was hypothesised that this tentative classification scheme would adequately differentiate between "good" and "poor" laterites for pavement construction, the scheme had not been validated. This paper summarises the details of an accelerated loading trial, using the Accelerated Loading Facility (ALF), of five test sections composed of two types of lateritic gravel and constructed to two construction standards. A laboratory repeat load triaxial testing program was also conducted to complement the field evaluation. Two of the experiments were conducted in order to examine the performance of the pavements after they had been exposed to a sub-tropical summer season for about six months in an effort to determine if there had been any moisture penetration into the pavements during this period and, if so, what effect this had on performance. As a result of the trial, the Corps have revised their classification scheme which appears to be a viable scheme based on current information which is quite limited for airfield applications. However, there remains much that can be done to verify and improve these recommendations. In particular, high tyre pressure aircraft (1,400 kPa and above) are a concern as no performance data on lateritic gravels for such traffic appears to be available. Recent developments in analytical modelling of granular basecourse material behaviour offer the potential to investigate this in the future through the conduct of a laboratory and analytical study to refine lateritic gravel criteria. (a)
Samenvatting