2007 - Norway - Otta Seal Pavement Experiences in Africa

Natural gravel materials have traditionally been used for upgrading earth to gravel roads or for regravelling existing gravel roads. However, serious concerns have arisen regarding the continuous use of vast amounts of gravel - a non-renewable, finite resource - which is not only being rapidly depleted in many countries but is also unsustainable in the medium to long term. This has prompted road engineers to consider the use of low-cost bituminous surface treatments on these gravel roads as an alternative to regravelling them in an unsustainable and
increasingly costly programme.

One type of surfacing that can provide an economic and practical alternative to traditional surfacings, such as the Chip seal, is the Otta seal. Unfortunately, lack of information regarding this relatively new type of bituminous surfacing has suppressed its more widespread use, despite its excellent performance in a number of countries.

This publication provides state-of-the-art information on the provision of the Otta seal surfacing as an economic and practical alternative to the more traditional bituminous surface treatments. The publication outlines the origin, properties, design and construction of the Otta seal and discusses its implementation impacts and the various factors that contribute to its sustainability. Finally, the paper provides information on the global use of the Otta seal, including two case histories relating to its introduction in eastern and southern Africa.

See here for another report on Otta Seals.