Local and overseas specifications and design methods of single, double, slurry, cape, sand, primer, and otta seals were compared to investigate potential surfacings for low-volume roads. The followingconclusions were drawn: (a) aggregate is rigorously specified for single, double, slurry and cape seals and little or no relaxation hasbeen considered, whereas the specifications for sand, primer and otta seals are not as rigorous; (b) binder is rigorously specified by relevant south african bureau of standards specifications for all seal types; and (c) formal design methods exist for single and double seals, but the designs of the other seal types are mostly empirical.A calculation of life cycle costs to road authorities over a 20-year period indicated that single and double seals are the most cost-effective over a wide range of traffic volumes. Low unit construction prices do not necessarily mean high cost-effectiveness, as the expected lifetime of the seal is an important consideration. This paper appears in transportation research record no. 1291, Fifth international conference on low-volume roads, may 19-23, 1991, raleigh, north carolina, volume 1.
Samenvatting