Development of a gyratory compaction procedure for laterite gravels treated with foamed bitumen

Abstract

Determining of the optimum density of the compacted foamed bitumen-treated materials is an important part of determining the field placement conditions. Laterite gravels tend to be highly susceptible to breakdown during laboratory compaction with the standard Proctor hammer, which may not be representative of field conditions. In this paper, a new method is presented for determining the optimal compaction characteristics of laterite gravels–foamed bitumen mixes. A gyratory compactor was used for compaction. The modified locking point concept was used to determine the number of gyrations to compact mixes of laterite gravels and foamed bitumen. The optimal compaction moisture content was subsequently established at this point. The average number of gyrations that gave the locking point was 44; optimum moisture content (OMC) for compaction varied from 86% to 92% for gravels only. The modified locking point seems to be suitable for determining the optimal compaction characteristics of these mixes.

Keywords:

• foamed bitumen
• laterite gravels
• gyratory compaction
• locking concept
• moisture content

Acknowledgements

The authors are grateful for the financial assistance by Swedish International Development Agency (SIDA) towards this work. Also, the resources at Division of Highway and Railway Engineering of KTH, Sweden, are highly appreciated.