Research into the properties of lateritic gravels and their impact on pavement design

[摘要] ENGLISH ABSTRACT: Laterites are used extensively in the tropics as road building materials in unboundbase, sub-base layers and in surface layers. However, most base course specificationsusually require the provision of crushed and graded stone or stabilized base and oftenexclude the general use of as-dug laterites or other naturally occurring gravels.Various field studies in the past have clearly indicated that many lateritic graveldeposits can be used successfully as base course materials in roads carrying low tomedium traffic without incurring additional maintenance costs and with considerablecost savings in pavement construction rehabilitation.Further research is needed for the more precise definition of the relationship betweenlaterite characteristics, traffic loading, environment, and pavement performance. Inthis study, extensive use was made of static and cyclic triaxial testing to investigatethe fundamental behaviour of a lateritic gravel material. The tests produce informationfor characterizing the shear strength, stress-strain properties and behaviour underrepeated loading. The gravel was sourced from stockpile at Malans Transport borrowpit at Maaitjies Kuil near Cape Town. Testing was conducted on the material both asgranular material and stabilized with cement and foamed bitumen. Testing was doneunder various conditions of stress, moisture and compaction. The resilient modulus ofthe lateritic gravel was found to be affected by moisture and compaction apart fromthe stress condition. Well known models were used to characterize the stressdependentresilient modulus. A model for prediction of permanent deformation wasdeveloped which together with the resilient modulus model were applied to the designof a light pavement structure composed of lateritic gravel base.

[发布机构] Stellenbosch University