New Zealand Experience with Foam Bitumen Stabilization

• Published in: Transportation research record Vol. 1868; no. 1; pp. 40 - 49
• Main Author: Saleh, Mofreh F.
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 2004
• ISSN: 0361-1981; 2169-4052
• DOI: 10.3141/1868-05

Foamed bitumen stabilization is burgeoning steadfastly and internationally. Although it involves higher initial material costs than cement or lime stabilization, it offers the advantages of being free from transverse shrinkage cracking and of being a fast technique that minimizes traffic delays. This work forms part of a larger project aimed at investigating the feasibility and potential applications of the foamed bitumen stabilization technique to speed its adoption in New Zealand. In this research, the foaming characteristics of two sources each of two grades of bitumen currently in use in New Zealand are presented. The effect of bitumen source and grade and the type of fines were studied. Fly ash Type C was used to modify the aggregate gradation to adjust the percentage of the fine fraction (passing the 75μm sieve). Portland cement was used at 2% by the dry weight of aggregates as a partial replacement for the fly ash. The foamability results for each source were quite different. For each source, the softer grade provided better quality foam than the harder grade. Two groups of mixes were prepared. The two groups were identical except that the first group contained 2% portland cement as a partial replacement of the fly ash. Optimum foam and water contents were determined for the two groups. The effect of curing time on the resilient modulus of foam-stabilized mixes was investigated. Both groups showed high resilient modulus values and rapid rates of increase of the moduli with curing time.