Published: August 2007 | Category: Activity management , Research programme , Research & reports | Audience: General
A laboratory study was undertaken to determine the effect of grading/particle size distribution on permanent deformation in multi-stage repeated load triaxial (RLT) tests.
Results showed the coarse gradings with a Talbot’s exponent n-value of 0.8 had the least amount of permanent deformation for high-moisture contents near saturation.
Finer gradings with an n-value of 0.3 had the least deformation in all of the tests in dry conditions at less than 70% of optimum moisture content. Similar performance in terms of permanent deformation was obtained if variations of the n-value were less than 13%.
Based on limiting the variations in n-value to ± 13% new grading envelopes for use in the new Transit New Zealand specification for RLT testing were proposed.
Keywords: Aggregates, basecourse, deformation, grading, particle size, distribution, performance specifications for aggregate, permanent deformation, recycled materials, repeated load triaxial, rutting
