Description
Bitumen rubber asphalts and seals were first introduced to the Republic of South Africa around 1983 and some 150 000 tons of asphalt were paved over the first 15 years. Recently approximately 30 of the original projects were inspected and evaluated. These results together with the original mix characteristics are furnished in this paper.
It is concluded that the bitumen rubber stress absorbing membrane interlayers (SAMI’s) and asphalts performed above expectations. Many of these SAMI’s and asphalts (paved under difficult traffic conditions and overlying severely distressed pavements) outlived their design period comfortably. The bitumen rubber overlays out-performed the conventional asphalts, under identical conditions, by a large margin.
Bitumen rubber asphalts and SAMI’s are especially suited for highly trafficked roads with pavements in structural distress and where overlays will eliminate re-working options in congested traffic situations. The authors conclude that the somewhat higher construction costs are negligible in view of the extended service life rendered by the bitumen rubber asphalts and SAMI’s, and the new revitalised interest in bitumen rubber overlays in the South Africa is justified.
