442 CAN. GEOTECH. J. VOL. 14, 1977

vides useful insights into the behaviour of a frozen saturated soil-water-ice system, with particular emphasis on the thermodynamic relationships involved. The work reflects the same excellent experimental technique that was a feature of the author's work at the NGI and is of interest to those concerned with the prop- erties of frozen soils, both from a research and practical point of view.

In reading the volume, this reviewer found a few unfortunate errors, such as lines missing from the text or added superfluously. However, the overall production of the volume is of high quality. The book should be purchased by public, university, and company libraries: as well, most practicing engineers and engineering

geologists should find enough material of value to them to justify the purchase of the volume for their own use and edification. Finally, the nature of this memorial volume and its his- torical appeal should attract those who ad- mired the many talents of Laurits Bjerrum.

J . C. O ~ L E R Department of Civil Engineering

and Applied Mechanics, McGill University,

Montreal, P.Q., Canada H3A 2K6

Lo, K . Y., Bozozu~, M., and LAW, K . T. 1976. Settle- ment analysis of the Gloucester test fill. Canadian Geotechnical Journal, 13, pp. 339-354.

Laterite soil engineering, pedogenesis and engineering principles

Received January 19, 1977

Accepted April 13, 1977

Lrrterite soil engineering, perlogenesis and engit~eering principles. By M . D. Gidigasu. Elsevier Scientific Publishing Company, Amsterdam, Oxford, New York. 1976.554 pp. $76.95 U S .

Can. Geotech. J., 14,442(1977)

The increasing involvement of Canadian engineers in overseas projects, involving tropi- cally weathered soils, makes this book on laterite soils very timely. The author's stated objectives are:

1. To present an up-to-date review of avail- able information on the geotechnical charac- teristics and engineering behaviour of laterite soils.

2. To show, that contrary to an apparent belief that all laterite soils are different from natural soils and are problem materials, a great majority of laterite soils can be evaluated for engineering purposes using the currently accepted theories and test procedures estab- lished for temperate zone soils.

3. To highlight the geotechnical implica- tions of the pedogenic processes of tropical weathering and laterization and to emphasize the contributions of the consequences of these processes to the deviations of engineering be- haviour of the problem laterite soils from the expectations of conventional soil mechanics, as

developed in Europe and North America for temperate-zone soils.

4. The fourth and main purpose of this book is to show that a very useful and logical approach in the identification and evaluation of laterite soils for engineering purposes is the modern and inspiring concept based upon the pedological considerations.

In the reviewer's opinion, the author has succeeded in meeting these stated objectives. Although many practising geotechnical engi- neers might argue the point that the concept of utilizing pedological considerations is neither new nor unique, nonetheless, the author is to be complimented for having produced one of the very few comprehensive books dealing with the solving of geotechnical engineering problems, based on pedological considerations.

Tropical weathering and laterization essen- tially involve chemical and physico-chemical alteration and/or transformation of primary rock-forming minerals into materials rich in clay minerals and laterite constituents (Fe, Al,

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Ti, and Mn). The author identifies three major stages in the laterization process as follows:

1. physico-chemical breakdown of primary minerals and the release of constituent ele- ments (SO2, &03, FeaOs, CaO, MgO, K20, etc. ) ;

2. laterization, which involves the leaching under appropriate drainage conditions of com- bined silica and bases and the relative accumu- lation, or enrichment from outside sources, of oxides and hydroxides of sesquioxide (mainly A1203, FeaOs, and Ti02) ;

3. dehydration or desiccation which in- volves partial or complete dehydration (some- times involving hardening) of the sequioxide- rich materials and secondary minerals.

In the past, there has been much confusion in the engineering literature concerning what constitutes a laterite soil, with various writers adopting different chemical, geological, and pedological definitions. The author's suggested solution to this problem is to use a very broad and general definition that encompasses all of the tropically weathered, reddish-coloured soils. These may be residual or nonresidual, and may range from decomposed rock through clays, to sesquioxide-rich, indurated crusts. Thus, as far as this book is concerned, the term laterite soil encompasses all of the above three stages in the laterization process and does not imply any particular textural, composi- tional, or morphological properties. Having taken this forward step, the author then pro- ceeds to attempt to distinguish between differ- ent laterite soils on the basis of their geotech- nical properties.

Various sections of the book cover such basic geotechnical items as: grain size distribu- tion, plasticity, problems with conventional soil classification systems when applied to laterites, shear strength parameters, compres- sibility, permeability, compaction, and soil stabilization using various additives. In sum- mary, the author concludes that the conven- tional soil mechanics tests can be applied to most laterite soils. The notable exceptions to this general rule are the so-called "Problem laterites."

"Problem laterites" are identified by the author as residually weathered soils formed in regions of recent volcanic activity and/or con- tinuous wet climate with average annual rain-

fall in excess of 60 in. (152 cm). They have high natural water contents, high liquid limits, low natural densities (20-70 pcf; 320-1 120 kg/m"), and crumbly structures. These soils often are of low compressibility, are highly permeable, and have high friction angles. The crumbly or granular nature of these soils ap- pears to derive mainly from free iron oxides which are adsorbed on the surfaces of the clay minerals.

The major difficulties encountered with the "problem laterites" is that they do not give re- producible results using standard classification test procedures. The author discusses this mat- ter at some length and explains that the prob- lem relates to such items as:

tendency to form aggregations on drying, loss of water from hydrated minerals on

drying, breakdown of concretionary structure on

remolding. The first two items could cause a large re-

duction in plasticity, an apparent coarser gra- dation, and a change in the moisture density relationships. The last item could cause a large increase in plasticity, an apparent higher clay content, and changes in the moisture density relationships. Obviously, such changes in the basic soil structure could also affect such parameters as : strength, compressibility, per- meability, etc.

The author proposes a series of index tests for identifying the "problem laterite" soils. A table relating probable in situ behaviour to the recommended index tests is also presented. By carrying out the index tests for a particular laterite soil and comparing the values of the physical and engineering properties obtained with those in the table, one can determine whether or not the soil is potentially trouble- some.

The last chapter in this book presents field performance data for engineering structures located in laterite soil areas. Generally, this section is interesting and informative, as it touches on such matters as: use of laterite soils and gravels in sub-base and base con- struction for highways, use of laterite soils in earthfill dams, stability of slopes, and founda- tion support of structures. Several tables and charts are presented which provide empirical correlations relating to gradation curves for

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444 CAN. GEOTECH. J. VOL. 14, 1977

base courses, performance of base courses, and slope stability studies. In addition, a table is presented summarizing the geotechnical char- acteristics of typical laterite soils used in the construction of several earthfill dams.

In the reviewer's opinion, this book pro- vides an excellent starting point for the geo- technical engineer who wishes to become fami- liar with laterite soils. Although it contains little that is new or original, it does clearly set out the basic mechanics of laterite soil beha- viour and points out the shortcomings of our present knowledge. Moreover, the suggested

approach of attacking geotechnical problems from a pedological viewpoint is, in the re- viewer's opinion, worthy of merit. A minor criticism is that the book does not contain a glossary of the many technical terms employed throughout the text. This would greatly help the geotechnical engineer who might be un- familiar with some of the pedological ter- minology.

E. J . KLOHN Klohn Leonoff Consultants Ltd.,

101 80 Shellbridge Way, Richmond, B.C., Canada V6X 2 W7

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