7. Sampling and testing
Published:January 01, 2001
This chapter considers the tests and procedures used to describe or evaluate the physical, mechanical and chemical characteristics of aggregates, for the purposes of (a) prediction of the likely ‘in service’ behaviour of the material (b) comparison between competing materials (c) specification compliance or (d) quality control. Individual limits are not discussed here but are considered in the appropriate Chapter. Sub-base materials (Chapter 10) sometimes have to use tests in BS 1377, but this section confines itself to BS 812 and the relevant standards from other countries.
The first step is the collection of samples. Statistically, a sample can be defined as an individual or group of individuals drawn from a large or infinite population, Information obtained from samples is only as representative of the material as the samples on which they are performed. If observations reveal little variation and there has been no bias in collecting, then a small sample or small number of samples may be highly representative of a population. If the variation is large then more and/or larger samples will be required Representative sampling, however, is perhaps the most difficult of the control operations to perform satisfactorily. Sampling, as with all types of test, introduces sources of variation and error, so that judgements of materials based on infrequent random tests are fraught with difficulties. In this connection, see also the remarks on sampling in relation to classification given in Chapter 6.A random sample is one in which each potential observation has an
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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).