BRE information paper has the edge on insulation

Books and publications gripped the economy so concrete p ~ - , duction has slackened and output of the r~ady-mixed material has inevitably declined. But that may not be sufficient to account for the lack of a bigger share of overall concrete output, for which many in industry have argued a good case; after all (it could be claimed) producers were full-time professionals handling huge volumes of materials and a wide range of mixes, with a fund of expertise that should command attention and respect. But there has always been some antipathy, especially from entrenched specifiers, who were suspicious and needed little prompting to dampen any incipient approbation for such a change from conventional site-mixed concrete. (And some major site-mixed producers were quite happy to agree.) However, suppliers of ready-mixed concrete are also, themselves, to blame; there have been numerous instances - no doubt miniscule in proportionate terms - of malpractice, as ill-prepared producers sought to take advantage of high demand (especially during the 1970s) and as competition became fierce. It is unfortunate that such occurrences have such unbalanced effects, but they do. Underpinning this industry has been the B R M C A which has been striving, with some excellent support from stalwart and enlightened producers, to achieve acceptance of standards of quality sufficient to engender confidence in the product. In the U K environment this has not been easy; but with, at least, three distinguished directors, of whom a co-author of this manual was one, very good progress has been made and there are certainly far fewer grounds for antipathy now. Indeed, this publication exemplifies the careful, sound approach that has been evident, over the years, to those prepared to listen, to think, I~o judge and to decide, without recourse to blind prejudice. The book is aimed at a wide readership, from contracts manager, site engineer and contractor's buyer, through members of pertinent professions, to makers, users and testers of ready-mixed contr&e and to academics and researchers. It is a very wide net, to catch a very large section of those involved in construction; whether it is read by many of them is unlikely - we are not known as a nation of book lovers and the construction industry may have more than its share o f bibliophobes - but, certainly, all would benefit from reading it or from dipping therein for reference purposes. The contents, which have been updated to take account of recent, important, changes in specifications for cements and concrete, are quite wide ranging and include, in a logical sequence, sections on materials, properties of concrete, mix design, application of statistics, quality control, sampling

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and testing (all in Part 1), followed by Part 2, which deals with practice, including production, specifications, siterelated aspects, organizations concerned wtih ready-mixed concrete and an appendix on QSRMC (Quality Scheme for Ready Mixed Concrete) technical regulations. There is also an appendix giving data on the recently introduced (and radical) designated mixes from BS 5328: 1991, and a very good list of 145 references, with a list of relevant British Standards and a useful index. Throughout, the text is generally clear, apt, informative and a reflexion of opinions based on wide and deep experience of the subject matter. Dealing with a material such as concrete there are the expected cautionary nuances, 'may avoid the necessity to', 'may mean that', but the authors do not shirk direct, clear, statements when they wish to make a point: 'In the case of the false-setting cement, there is a fast loss of workability which can be regained if the concrete is remixed or vibrated (61) as shown diagramatically in Figure 2.5'. (Reference 61 is to work by one of the authors, JDD, reported in 1973.) Figures, tables and text are clear and well presented; technical points are consistently attributed, as above, to checkable sources. There seems to be only one reference to a private communication and that refers, carefully, to practice reported to have been used in Australia. There are, unsurprisingly, a very few minor technical points that one might quibble over: bulk density is less for dampfine aggregate (page 19, 1.1.7, para 2); the Gaussian distribution is associated with random effects (which is not made explicit on pages 106--107); on page 105 the coefficient of variation is listed and used on page 109, but is not defined. (These are perhaps more a sign of pedantry in your reviewer than any lack in the text.) There are also, perhaps inevitably, some editorial aberrations which have escaped proof reading. There is confusion over the first three figures, their captions and the corresponding references in the text. On page 7, the second sentence in paragraph 4 is almost identical to that in paragraph 7. And on page 94, in 4.2.2 Step 34 refers to the 'highest' cement content where only two are involved. (There are some cases of misprints, omissions or unwanted inclusions, which have little effect on the meaning.) These are not criticisms of the technical quality of the book, nor, indeed, of the authors. They are not consistent with the general high quality of the book and should not have been missed; someone should have noticed. This is a proper manual; it will be of great help to anyone wishing to understand and/or participate in the whole process (and service, as the authors would claim) of providing ready-mixed

Construction and Building Materials 1994 Volume 8 Number 1

concrete. But a good deal is relevant to concrete technology in general, presented in no less an authoritative and straightforward a manner than is to be expected from such experienced, wellinformed authors. It should be noted and welcomed by all sectors of the industry and is a major contribution to the topic. At £24.95 and 245 pages it is excellent value and strongly recommended; the authors deserve congratulations and their industry is lucky to have such representatives. Frank D. Lydon

BRE Information Paper has the edge on insulation Insulating floors at their edges helps to improve energy efficiency in buildings by reducing overall heat loss and thermalbridging effects at the floor edge. BRE Information Paper 7/93 'The U-value of solid ground floors with edge insulation' gives a method for determining the Uvalue of solid ground floors incorporating insulation at the edge. The groundfloor U-value obtained by the procedure can be used for compliance with building regulations on thermal insulation. The paper identifies the two types of edge insulation - vertical and horizontal - and provides tabulated data on their thermal insulation properties. It also sets out worked examples for further guidance. Copies of IP 7/93 'The U-value of solid ground floors with edge insulation' are available from the BRE Bookshop, Building Research Establishment, Garston, Watford WD2 7JR, price £3.50 each (plus 35p p&p).

223 timbers in BRE strength properties report Data on 223 timbers are included in the BRE Report 'The strength properties of timber' (formerly sold by HMSO), which is now available from the BRE Bookshop. The report contains the results of physical and mechanical tests on 223 hardwoods and softwoods in the green