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New introductions to the 2005 edition of
Cements, Limes, Plasters
A facsimile of the third (1928) edition
Edwin Eckel
New introduction by Paul Livesey (UK)
Edwin C. Eckel was the most influential author on cement, lime and plaster in the United States of America in the first part of the twentieth century. This book is more than just a domestic chronicle and contains much of interest for the international conservator and student of cement, lime and plaster.
A geologist with the United States Geological Survey, Eckel was commissioned to draw together the extensive but widely scattered information on cementing materials. The timing of the survey was opportune in that it was contemporaneous with the demise in use of hydraulic lime, the brief but meteoric rise in popularity of natural cements and their rapid eclipse by Portland cement. His early surveys set the pattern whereby, by the time of this publication, he was recognized as America's specialist in cementing materials and their production industries.
Eckel was widely travelled and corresponding with leading chemists and producers, particularly in Europe, this edition therefore reflects the rapid developments in the international knowledge of the materials and their production. It puts the American scene in context with information from France, England, Belgium, Germany and Italy on the analyses of hydraulic limes, Roman and natural cements, Portland cements and their raw materials.
Eight material groups are set out detailing their raw materials, chemistry, locations, and processing techniques. These are divided into gypsum and the plaster cements; limes, lime burning, the properties of lime, the preparation and hydration of lime and the manufacture of lime-sand bricks; magnesia and oxychloride cement; hydraulic lime, selenitic lime and grappiers cement; natural and Roman cements; Portland cement including a chapter on high-strength variants; pozzolana and slag cements; and a chapter on the recently developed alumina cements.
Chapters on the developing understanding of Portland cement might equally be applied to hydraulic limes. General principles that the raw mix should be of the correct composition; the materials should be of an appropriate fineness and intimately mixed to ensure chemical combination; burning temperature should be controlled to an optimum level for the particular mix; and that the resulting product should be ground to a suitable fineness are as true in the twenty first century as they were at the start of the nineteenth century.
The final chapter on 'accelerated or high early strength' cement takes these factors to the optimum necessary for its production. Again, principles are valid for the present-day producer of both Portland cement and hydraulic lime involving even tighter quality control of raw materials; more efficient burning and finer grinding. Many in the conservation world will recognize that such highly reactive cements are not always compatible with traditional building fabric.
It is of interest that the concept of 'ideal' cement is proposed as one where the constituents are simply silica and lime in sufficient proportions that when combined they produce just 'tricalcic silicate', now referred to as alite or tri-calcium silicate. It was accepted that this was too theoretical to be possible at that time but that when the limitations of rotary kiln processing were replaced by blast-furnace technology this might change. A description of the role of liquid phase in the rotary kiln, reducing necessary temperature for conversion from lime to tri-calcium silicate, shows the beginning of an understanding of the processes involved.
The question of content of magnesia in cement had been debated in Europe for many years and limits of around 3 per cent had been adopted. Eckel brought together this concern with the practical evidence of cements from Lehigh Valley containing 4 or 5 per cent and experience with natural cements having magnesia contents as high as 10 per cent. His conclusion was that, with due care in their mixing and burning, Portland cements with up to 5 per cent magnesia would be sound.
Consideration of the role of alumina brought in references to the work of the French chemist, Le Chatelier. The balance between the shortened setting times with more alumina and the risk of 'destruction' by sea water is discussed, recognizing that a range of alumina contents was acceptable from 1 or 2 per cent up to 7 or 8 per cent, depending on intended use of the cement.
Eckel, in the first edition of this work, introduced the concept of a cementation index based on molecular weights of product constituents. His conclusions, although revolutionary in its time, are so close to the modern 'lime saturation factor' as to be readily acknowledged by modern chemists. By this third edition it had been refined to also include magnesia and an understanding of the effects of fuel and kiln lining materials. The point is well made that this is a good guide to initial raw material selection but that each kiln system requires fine adjustment to the mix for an optimum product to be assured.
The chapter on alumina cement, defined as a product containing from 65 to 90 per cent of calcium aluminate, displays all of the early enthusiasm by which the product was greeted. The experience from France, Belgium, Germany and Switzerland is presented along with detailed analyses of suitable raw material deposits in America. There is an understanding of the energy required to fuse a suitable mix, and the consideration of the likely increasing cost of coal production and reducing oil resources has an echo for the modern producer.
A major value for the conservator in America and Europe are the detailed tables in this work. Chemical analyses of limes, plasters, natural cements and Portland cements will offer the potential of identifying original materials and developing sympathetic repair or replacements so essential for compatibility with remaining building fabric. The principles of material science proposed are not always completely in line with modern scientific thought but are rarely so wrong as to lead to significant error. This is a most interesting and readable publication.
Paul Livesey BSc (Tech), EurChem, CChem, MRSC
Paul Livesey is a cement chemist currently involved with various research projects on cement, concrete, and mortar on behalf of Castle Cement Ltd., and is the UK representative to European Standards committees on cement and building lime specification and testing. He is participating in a Foresight research project into the characteristics and performance of natural hydraulic lime mortars where he is responsible for the chemical analysis and physical test programme.
New introduction by William G. Hime (USA)
The first edition of Edwin C. Eckel's book, Cements, Limes and Plasters, was published in 1905, before Portland cement came into wide use in the United States. The second edition, in 1922, then added 19 chapters devoted to Portland cement, plus chapters on gypsum products and 'magnesium cements'. This third edition, published six years later, detailed changes in Portland cement that allowed higher strengths, and the emergence of 'alumina cements', known later as 'high alumina' and 'calcium aluminate' cements.
Although the book will largely be used as an impressive historic account of the 'materials, manufacture and properties' (the subtitle) of Portland and other cements, limes and plasters during the first quarter-century of the 1900s, it will find great use in identifying and reproducing cements for historic restoration purposes. Its splendid tables - 269 of them - cover compositions of plasters and cements as produced in various areas of the United States and often many European countries.
Throughout the book Eckel includes interesting economic data. For example, he notes that American economics dictated different approaches from the European. The high U.S. cost of labor and low cost of fuel led to complete conversion of kilns to 100 per cent use of rotary kilns by the early 1900s, while low labor and high fuel costs helped keep vertical ones operating longer in Europe.
Table 2 presents average commodity prices for the period 1890–1927. Prices remained nearly constant to 1904, but increased by a factor of nearly 2.5 in the eight-year period from 1912 to 1920 and then fell dramatically by 1927! Considering the tremendous decrease in the value of the dollar since then, it is astonishing that Portland cement and concrete costs only about two cents a pound in 2005. Eckel would have not been surprised by that; on page 6 he states 'the price level of 1950 may be substantially that of 1900'.
The opening chapters on plasters and limes are not only of historical interest but are largely still relevant. The mention of 'Lafarge cement' on page 189 is interesting since Lafarge now owns a good percentage of U.S. cement companies. The reference, however, is to grappier cements, which are no longer sold in the U.S. but have a composition not greatly different from Portland cements. Indeed, as Figure 33 shows, grappier mortars had a higher tensile strength than Portland mortars.
Eckel's use of tensile strength data is in contrast to present-day practice of seldom measuring that property, especially for gypsum systems.
The natural cement chapters provide great reference data for use in historical restoration work. The variances in compositions between States are large. The tables on tensile strength show remarkable differences between such cements.
Eckel's coverage of Portland cement largely covers the period when enormous changes were made in the production equipment. Grinding mills became much more efficient, allowing quicker gain in concrete strength, and, incidentally, requiring increasing gypsum contents.
As mentioned, the United States led the world in conversion of kilns from vertical to rotary and horizontal. By the time of this edition, the entire U.S. industry had converted. As he does throughout his book, he provided details of elevation, section and plan diagrams of such equipment. He discusses kiln fuels and provides an interesting side comment on arguments for use of plaster rather than gypsum.
Mill costs and cement prices are discussed and his Table 215 is especially interesting. With all of the enormous changes in cement production equipment and its cost, the price of cement had more than doubled in the period from 1910 to 1920, but in 1925 was less than that in 1890!
If Eckel's book had any fault it was perhaps his inability to predict misuse of the materials he discussed. Oxychloride cements, for example, were quite popular to the mid twentieth century, but that popularity died with the use those cements where they could get wet, causing disruptive expansion and corrosion. Gypsum products were combined with Portland cement to produce the best of both products. Unfortunately, they often produced the worst: destructive expansion in a wet environment. Structures made with alumina cements failed dramatically in the 1970s, leading to a ban on them for use in structural elements in many countries. Aside from that deficiency, it is difficult to express anything but the highest praise for this third edition.
In his preface to the 1905 edition, Eckel notes that the:
... volume was planned and partly written in 1901. If it had been published at that date the words 'probably and possibly' would not have occurred so frequently as they do in the present work, for at that time the writer felt a cheerful certainty in regard to many points which now seem less obvious.
Eckel certainly did not need frequent use of such words in the third edition; he had covered his subjects well.
Edwin C. Eckel died in 1941. His obituary in the Chicago Tribune reads:
Knoxville, Tennessee, November 22 (AP). - Maj. Edwin C. Eckel, 67, chief geologist of the Tennessee Valley Authority, died tonight at his farm home near here. Death was attributed to a heart ailment. Maj. Eckel was a veteran of the World War. He held a lifetime honorary membership in the American Society of Civil Engineers, was a fellow of the Geologic Society of America, and was the author of several books, one entitled Coal, Iron, and War. Among the survivors are his widow of Washington, D.C., and a daughter, Miss Julia Eckel, Washington artist.
The Tribune account misses this book and its
importance.
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