Use of Coral-Derived Aggregates for Construction of Low-Volume Roads

Many tropical island and coastal regions suffer from a paucity of recognized engineering aggregates. In these regions river gravel and old uplifted coral reef formations are often the only economically viable materials. Typically, the coral-derived material most widely available for use is termed coronous material, a land-based uplifted coral reef that may contain an abundance of plastic fines and that is usually easily excavated without the use of explosives. The shortage of traditional aggregates and the availability of the upraised reefs have promoted the study of the use of coral-derived aggregate as an alternative aggregate in pavement engineering works. Although coral-derived materials have been successfully used for pavement construction in the past, traditional engineering tests have generally indicated that it is a substandard product, and material from most pits does not pass typical specification tests. The material properties and the historical use of coronous materials in road construction are summarized, and a draft guide for the use of coronous materials in the road base and subbase for both sealed and unsealed road pavements is provided.