"TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 445: Practices for Unbound Aggregate Pavement Layers consolidates information on the state-of-the-art and state-of-the-practice of designing and constructing unbound aggregate pavement layers. The report summarizes effective practices related to material selection, design, and construction of unbound aggregate layers to potentially improve pavement performance and longevity."--Publisher website.

Nearly all highway, airport, dock and industrial pavements contain large quantities of untreated aggregate in the form of unbound pavement layers. In many pavements, which are lightly or moderately trafficked, crushed rock or gravel derived aggregates comprise the majority of the construction or, in the case of unsealed pavements, all of the structure. This book provides studies of the performance and description of this material that will help the reader to better understand its characteristics and behaviour both alone and as part of the pavement structure it forms. This work will be useful to practitioners, policy makers, researchers and students. It forms a sequel to the earlier book "Unbound Aggregates in Road Construction" also published by Balkema

Unbound Aggregates in Roads contains the proceedings of the International Symposium on Unbound Aggregates in Roads (UNBAR3) held at the University of Nottingham, England, on April 11-13, 1989. The papers focus on unbound aggregates used in road construction and cover topics ranging from drainage and permeability to placement and compaction of unbound aggregates, design philosophy, specification, and compliance. This book consists of 49 chapters divided into eight sections and opens with an overview of the functions of unbound aggregates in roads, followed by a discussion on the mechanical properties of different aggregates and theoretical aspects of granular materials. The following chapters focus on granular drainage layers in pavement foundations; residual stresses caused by compaction in granular materials; and alternative materials for road construction such as steel slags and natural and waste materials. The use of unbound road aggregates in various countries such as Italy, France, Germany, and Portugal is also considered. This monograph will be a useful resource for designers, aggregate producers, contractors, specification writers, and materials engineers.

Explores performance-related procedures to test and select recycled hot-mix asphalt and portland cement concrete materials for use in unbound layers of highway pavements. Appendixes A through C of NCHRP Report 598, which cover the literature review and background information, new aggregate tests, and surface dielectric measurements, were published as NCHRP Web-Only Document 119.