Otta Seal Surfacing

Abstract

Natural gravel materials have traditionally been used for upgrading roads from earth to gravel or for regraveling existing gravel roads. However, serious concerns have arisen regarding the continuous use of vast amounts of gravel—a nonrenewable, finite resource—which not only is being rapidly depleted in many countries but also is unsustainable in the medium to long term. This problem has prompted road engineers to consider the use of low-cost bituminous surface treatments on these gravel roads as an alternative to regravelling. 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. In view of this problem, 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 is presented. The origin, properties, and design and construction of the Otta seal are outlined, and its implementation impacts and the various factors that contribute to its sustainability are discussed. Brief information is presented on the global use of the Otta seal.