9. Aggregates for mortar
Published:January 01, 2001
This chapter, which is concerned with aggregates for mortars, necessarily introduces some degree of overlap with Chapter 8. However, there are major differences between mortars and concretes, arising mainly from the manner of their use.
The term ‘mortar’ is used in the building industry to denote a mixture of natural sand or other fine aggregate and some binding agent, used as a jointing or a surface plastering and rendering material (Fig. 9.1). In the United Kingdom the demand for building sand grew steadily up to 1973 to reach a peak of 23.6 Mt, representing some 18% of the total sand and gravel production (HMSO 1989) for the country. Since then it has fluctuated considerably, falling to 15.7Mt in 1981 but rising again to 21.89 Mt in 1988 (Fig. 9.2). It should be noted that the output figures for building sands are far in excess of figures for mortar production.Until about 30 years ago the choice of binders in the UK was limited to lime or cement or cement-lime mixes. Mortars made with lime alone as binder are no longer used for building except for some specialist applications in the repair of historic buildings. The choice of cementbinders has been widened to include masonry cementS(specially blended mixtures of Portland cement with finely divided mineral plasticizers and air-entraining agent). Increasingly, air-entrainment in mortars, not only to confer frost resistant properties but also to aid workability, is being used even with cement/lime/ sand mortars. The use
Until about 30 years ago the choice of binders in the UK was limited to lime or cement or cement-lime mixes. Mortars made with lime alone as binder are no longer used for building except for some specialist applications in the repair of historic buildings. The choice of cement binders has been widened to include masonry cements (specially blended mixtures of Portland cement with finely divided mineral plasticizers and air-entraining agent).
Increasingly, air-entrainment in mortars, not only to confer frost resistant properties but also to aid workability, is being used even with cement/lime/sand mortars.
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).