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The solidification of Portland cement
96
Book Reviews
effect of adjacent buildings on the wind pressure distribution is to be considered. The remainder of the book, which comprises 138 out of the 486 pages, applies the theory of jets and exhausts discussed in earlier chapters to air douches, air curtains and fume and duct extract systems. As usual Baturin first demonstrates the theory and then discusses practical designs. Experimental evidence of the validity of the proposed design methods is given and the design data is presented in both tabular and graphical form. Fundamentals of Industrial Ventilation is a unique book and should be found on the shelves of all Heating and Ventilating library sections of colleges, major firms, research institutions and any
body with an interest in heating and ventilating. I do not think it is a good course book for students, as much of the basic theory is not included in the book. It is, however, valuable in the transitional stage from student to practising engineer. Generally Baturin's book should appeal to those who require more than simple "rule of thumb" design methods, and to the research worker as it is also a summary of recent Russian work in the Ventilation field.
M. J. HOLMES Heating and Ventilating Research Assoc., Old Bracknell Lane, Bracknell, Berks.
The Solidification of Portland Cement R. B. WILLIAMSON
Prog. Mat. Sci. 15, 189-286 (1972). Published separately. Pergamon Press. Price £1.75
THE AUTHOR refers to this as a review on a very selective basis. His object is to describe the setting and hardening of cement as a solidification process, drawing a parallel with the crystallization of an alloy from the melt. Solidification is defined as a process by which a solid grows at the expense of a liquid with which it is in contact. His evidence is largely based on the interpretation of ninety-nine electron micrographs, mostly scanning type, which are reproduced in the text. Nearly all these photographs were taken in the author's own laboratory. Following Powers and Brownyard and Taplin, Prof. Williamson distinguishes between the "inner" hydration products, those laid down within the boundaries of the original cement grain, and the "outer" hydration products, those laid down in the originally water filled space. (There are misprints in three of the tables illustrating this argument.) He then proceeds to identify the two types of product in his electron micrographs. A few of these show cement clinker, but without added gypsum. The other specimens were hydrated tricalcium silicate or dicalcium silicate. The presence of inner hydra-
tion products is demonstrated by the gradual replacement of unhydrated grains by hydrated matter, leaving pseudomorphs of the original grains. The outer products consist of a columnar layer following the outline of the cement grains and growing perpendicularly to their surface, and crystals of calcium hydroxide. The columnar structures of neighbouring grains eventually meet and grow together. This, and the growth of the calcium hydroxide crystals, accounts for the hardening process. At higher water:cement ratios, when the columnar product does not entirely fill the intergranular space, the capillary porosity can be seen. Finally, the strength of cement paste is interpreted in terms of the various flaws and stress concentrators which can be seen in the photographs. The quality and reproduction of these are excellent.
R. W. NURSE
Building Research Station, Garston, Watford WD2 1JR, Herts.
Book Reviews
effect of adjacent buildings on the wind pressure distribution is to be considered. The remainder of the book, which comprises 138 out of the 486 pages, applies the theory of jets and exhausts discussed in earlier chapters to air douches, air curtains and fume and duct extract systems. As usual Baturin first demonstrates the theory and then discusses practical designs. Experimental evidence of the validity of the proposed design methods is given and the design data is presented in both tabular and graphical form. Fundamentals of Industrial Ventilation is a unique book and should be found on the shelves of all Heating and Ventilating library sections of colleges, major firms, research institutions and any
body with an interest in heating and ventilating. I do not think it is a good course book for students, as much of the basic theory is not included in the book. It is, however, valuable in the transitional stage from student to practising engineer. Generally Baturin's book should appeal to those who require more than simple "rule of thumb" design methods, and to the research worker as it is also a summary of recent Russian work in the Ventilation field.
M. J. HOLMES Heating and Ventilating Research Assoc., Old Bracknell Lane, Bracknell, Berks.
The Solidification of Portland Cement R. B. WILLIAMSON
Prog. Mat. Sci. 15, 189-286 (1972). Published separately. Pergamon Press. Price £1.75
THE AUTHOR refers to this as a review on a very selective basis. His object is to describe the setting and hardening of cement as a solidification process, drawing a parallel with the crystallization of an alloy from the melt. Solidification is defined as a process by which a solid grows at the expense of a liquid with which it is in contact. His evidence is largely based on the interpretation of ninety-nine electron micrographs, mostly scanning type, which are reproduced in the text. Nearly all these photographs were taken in the author's own laboratory. Following Powers and Brownyard and Taplin, Prof. Williamson distinguishes between the "inner" hydration products, those laid down within the boundaries of the original cement grain, and the "outer" hydration products, those laid down in the originally water filled space. (There are misprints in three of the tables illustrating this argument.) He then proceeds to identify the two types of product in his electron micrographs. A few of these show cement clinker, but without added gypsum. The other specimens were hydrated tricalcium silicate or dicalcium silicate. The presence of inner hydra-
tion products is demonstrated by the gradual replacement of unhydrated grains by hydrated matter, leaving pseudomorphs of the original grains. The outer products consist of a columnar layer following the outline of the cement grains and growing perpendicularly to their surface, and crystals of calcium hydroxide. The columnar structures of neighbouring grains eventually meet and grow together. This, and the growth of the calcium hydroxide crystals, accounts for the hardening process. At higher water:cement ratios, when the columnar product does not entirely fill the intergranular space, the capillary porosity can be seen. Finally, the strength of cement paste is interpreted in terms of the various flaws and stress concentrators which can be seen in the photographs. The quality and reproduction of these are excellent.
R. W. NURSE
Building Research Station, Garston, Watford WD2 1JR, Herts.