This report details research carried out from 2016 to 2017 as the preparatory stage of a larger programme to understand how chipseals may be improved to withstand increases in horizontal shear forces imposed by traffic loadings. The research aimed to develop an understanding of mechanisms and factors that lead to chip loss resulting from surface shear stresses, and to develop a methodology for testing seal performance under realistic but controlled laboratory conditions.
The report commences with a literature review to collate and examine existing data and experience on seal selection and chip loss processes from New Zealand and overseas. Physical mechanisms, site and vehicle factors that contribute to seal damage are also investigated. Finally, an experimental test method and plan is developed to quantitatively compare and evaluate the effect of seal and binder type on overall seal performance in the laboratory, but under realistic loading and temperature conditions. The experimental plan is to be undertaken as the next stage of this project.
Keywords: chipseal; horizontal stress; surface wear; transverse shear stress; tyre-pavement contact stress.