Alternative materials for wearing course of concrete pavements: A critical review

The existing worldwide road length of concrete pavements is significant. Furthermore, concrete pavements have a number of specific applications, even though they are second to asphalt pavements in terms of current popularity. Besides, asphalt is a rapidly depleting resource, which might mean that concrete is the chief material for the future. However, concrete pavements have their drawbacks, such as high construction cost, low tensile strength, and significant contribution to global carbon-di-oxide emissions. The present study aims to address these drawbacks by reviewing the prominent alternative materials that may be utilized to replace cement and/or aggregates in concrete. The potential of alternatives such as coal ash, silica fume, nano-silica, fly ash, slag, and recycled concrete aggregate is investigated. In addition, the effects of adding fibers (as both fiber-reinforced concrete and engineered cementitious composite) to concrete pavements are discussed. This review will also help pavement engineers and researchers to ascertain which combination of materials to use so that mechanical properties better than conventional concrete are achieved. The specific advantages and disadvantages due to various combinations of materials, in several types of concrete pavements such as conventional concrete, roller-compacted concrete, and self-compacting concrete are discussed in detail.