Otta seal is a type of bituminous surface treatment that was developed by the Norwegian Road Research Laboratory (NRRL).
[1] Otta seal is formed by adding graded aggregate to a soft bituminous binding agent.
[1][2] Otta seal is formed in the following procedure: Otta seal is primarily used in places that do not have strict requirements for strength, grading, particle shape, binder adhesion, and dust content, which have low capital and expect relatively low traffic (up to 500 vehicles per day).
[1][3] Currently, Otta seal is most prevalent in Norway, Sweden, Iceland, and Botswana and common in Bangladesh, Australia, and parts of Africa.
[citation needed] Otta seal does not cause prolonged delays in traffic, it takes few hours to resurface a road and is usable almost immediately afterwards.
One negative impact is the loose gravel can cause chips or damage to windshields, but odds of this happening is lowered in slower moving traffic areas.
[4] Otta seal is a type of road surfacing consisting of a bituminous binding substance and aggregate rocks ranging from gravel to fine particles.
Bitumen binders that are more viscous tend to move through the aggregate faster, but are not as hard and cannot handle heavier loads.
Depending on where in the world the road is being constructed and therefore what types of rock are available, the strength of an Otta seal can vary greatly.
It is more amorphous, meaning it is weaker under compressive forces, but can hold the rocks together and limit cracking under tensile stress.
The bitumen molecular structure is composed mostly of compressed hydrocarbons, sometimes containing many other elements like nitrogen, oxygen, sulfur, and nickel.