11. Aggregates in bituminous bound construction materials
Published:January 01, 2001
Both natural and artificial aggregates of coarse and fine sizes are employed in bituminous mixtures for highway and airfield pavements (Fig. 10.1) and in hydraulic and building appHcations (The Shell Bitumen Handbook 1990).
The emphasis in this chapter is upon the use of bituminous materials in pavement construction. The same factors affecting mix density, strength, stiffness and adhesion, apply in hydraulic applications as in pavement construction. However, in the former, greater attention is paid to such properties as permeabiHty (which may be required to be high or low depending on the particular application), resistance to flow on steep slopes and, where relevant, to wave impact (Hills & McAughtry, 1986). Polishing resistance characteristics of aggregates clearly have no importance in hydraulic applications but, in building construction, mastic asphalts used in bridge decks and in decks and ramps of multi-storey car parks require a high skid resistance. Chief among the requirements of mastic asphalt for bridge decks, roofing and car parks is impermeability in order to protect the underlying concrete construction from water and frost attack and from the effect of de-icing salts and other chemicals (Mastic Asphalt Conferences 1989). The major factor in these applications is the mix design, involving use of a high bitumen content in accord with the high content of fine aggregate and filler in the aggregate grading.
It should be noted that, at the time of going to press, several relevant developments were taking place with respect to the
Figures & Tables
Aggregates: Sand, gravel and crushed rock aggregates for construction purposes
In 1985, the Geological Society published Aggregates as the first volume in its Engineering Geology Special Publication series. It met with immediate acclaim, being awarded the Brewis Trophy by SAGA in 1986.
“If your work involves the use of aggregates, buy this book and read no further; this volume will be an essential and valuable reference that you will use for many years.” (Canadian Geotechnical Journal 1988)
In 1989, the working party whose work had resulted in the publication of Aggregates was reconvened to revise, update and extend their report. Each chapter was reviewed by independent referees. The second and greatly improved edition, published in 1993 and reprinted in 1998, represented the distillation of a vast body of knowledge and experience held not only by the members of the working party, but also by many international experts, scientists and engineers who contributed as reviewers, referees and corresponding authors.
Owing to continued demand for this unique reference book, a group of aggregate specialists was convened in 1999 in order to review thoroughly and update Aggregates for this third edition.
Outline of contents: Introduction; Occurrences; Field investigations; Extraction; Processing; Classification; Testing; Aggregates for concrete; Aggregates for mortar; Unbound aggregates; Bituminous bound aggregates; Rail ballast; Filter media; Appendix: Aggregate properties; Glossary; Index.
Working Party Members and/or third edition Reviewers: Mr L. Collis (formerly Sandberg); Professor P. G. Fookes (Chairman; consulting engineering geologist), Mr R. A. Fox (formerly RMC Aggregates (UK) Ltd), Professor G. P. Hammersley (formerly Laing Technology Group, now BRE), Mr P. M. Harris (formerly BGS), Dr I. E. Higginbottom (formerly Wimpey Environmental Ltd), Mr J. Lay (RMC Aggregates (UK) Ltd), Dr G. Lees (formerly University of Birmingham), Mr D. I. Roberts (Land and Mineral Resource consultants), Mr A. R. Roeder (formerly British Cement Association), Dr I. Sims (Secretary; formerly Sandberg, now STATS Limited), Dr M. R. Smith (formerly Imperial College, now the Institute of Quarrying), Dr R. G. Thurrell (formerly BGS), Dr G. West (formerly TRL).