13. Aggregates for use in filter media
Published:January 01, 2001
Although the total volume of aggregate used for filters is relatively small, filters nevertheless play important and diverse roles in many projects. Table 13.1 shows some of the main uses of filter aggregates and the first four parts of this chapter discuss some of the requirements and properties of these materials. The final three parts of the chapter describe the functions and specification of filter aggregates in their three main applications, namely water filtration, effluent treatment and as drainage filters for earthworks and other civil engineering structures. These will normally be subject to different design criteria and may also call for filter materials with distinct sets of physical and mechanical properties.
Filter aggregates generally consist of sand, gravel or crushed rock. Manufactured aggregates are also occasionally used and these often include blastfurnace slags.
Although filter materials for water and effluent treatment works are often used in relatively small quantities, the high quality of aggregate normally required is not always readily available from commercial production processing, which may be designed to yield a satisfactory general purpose aggregate at least cost. On the other hand, drainage layers in major civil engineering works, such as embankment dams, are usually designed to make the best use of the available natural materials with the minimum of processing.
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).