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Review of Cements, Limes and Plasters from the Journal of Architectural Conservation

A well-thumbed copy of the second edition of Eckel's definitive text has sat on my bookshelf for many years. So when asked to review the reprint of the third edition, I jumped at the chance - perhaps someone will reprint the first edition and my collection will be complete.

This edition describes the development of a wide range of 'cementitious' materials, particularly through the nineteenth and early twentieth centuries. It covers the raw materials, production processes and material properties of plasters, limes (both hydraulic and non-hydraulic), natural or Roman cements, Portland cement, Pozzolanic cements and cements based upon calcium aluminate. In short, this book has something for everyone. It is interesting to track the changes between the first and third editions which reflect the growth of Portland and calcium aluminate cements and the decline of the natural cements over a 23 year period. 

Eckel, a US geologist, widely surveyed the field and brought together the work of many eminent scientists and engineers. A particular strength of the book is the collation of data from both American and European sources - clearly presented in some 269 tables and many illustrations. Each chapter contains sufficient references to permit the keen reader to delve deeper into the history of these important materials. Eckel himself recognised the American bias to these references, writing in the Preface to the first edition that a 'working engineer' might find 'that references to the proceedings of some German scientific society are apt to prove a vexation rather than an aid.' Nevertheless, references to the likes of Candlot, Zwick, Vicat, Le Chatelier and Bonnami attest to the breadth of coverage.

A book of this scope needs a unifying theme and Eckel provides this through his description of a Cementation Index. The ideas behind it are an extension of the concepts identified by the likes of Smeaton and Vicat. Although the assumptions upon which the calculation is based would nowadays be challenged, the Index is very useful in defining groups of inherently variable materials. Over the last six years or so I have been engaged in research to re-produce Roman cements of the nineteenth century. The Index has been useful in both selecting sources of raw material and guiding the identification of calcination parameters. The comprehensive data within the book has also provided the basis for judging the success of our laboratory efforts.

Eckel's book occupies a special niche in the literature in much the same way as does Lea's standard work on the Chemistry of Cement. Those conservationists wanting the equivalent of Neville's Properties of Concrete would be advised to also consult the classic works such as that of Gillmore. However, the book's approach is broader than this classification might imply. Eckel describes the effect of local economic conditions on the selection of technologies for material production, for instance, citing the relative costs of labour and fuel on the selection of kiln type. There is also a chapter dedicated to a review of ten 'Specifications for Portland Cement' covering the period 1896 - 1922; my only regret is that there is not a companion chapter for the natural cements.

If the book has a 'fault' it lies in the paucity of coverage of hydraulic limes, being only 27 pages.  However, this reflects the original American market for which the book was produced; Eckel states that no such material was manufactured in the US in the mid-1920s. Nevertheless, this book is essential reading for those wishing to both understand these historic materials and how scientists of the time understood them.

Dave Hughes (BSc, PhD)

Associate Dean, School of Engineering, Design and Technology, University of Bradford, UK

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