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Cohesion in colloidal soils

Published online by Cambridge University Press:  27 March 2009

F. Hardy
F. Hardy
Affiliation:
(Imperial College of Tropical Agriculture, Trinidad, British West Indies.)
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Extract

1. Experiments in which were measured the resistances to (a) transverse breaking, (b) crushing, and (c) parting under tensile pull of standard blocks of soil prepared in different ways and under particular moisture conditions are described and discussed.

2. The soils examined comprised three highly colloidal siliceous soils containing amounts of calcium carbonate ranging from 7·2 to 0·2 percent., and two red lateritic soils.

3. The most significant results were obtained by employing, in a special tenacity apparatus, granular test-blocks, prepared by moistening sieve-graded dry soil packed into rectangular moulds. The results thus obtained are believed to furnish a reliable measure of the cohesiveness of soil colloidal matter, especially in soil blocks that have previously been brought to constant moisture content in a humidifier. The method of preparation simulates the effect of rain in causing the “running together” of colloidal soil particles.

4. The relative cohesiveness of the soils examined appears to follow the same order as their rates of settling from aqueous suspension. This observation strengthens the view that cohesiveness in colloidal soils is to a certain extent due to chemical forces that depend on the presence of active atoms or atomic groups possessing powerful fields of residual affinity, although probably film tension also plays a part.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 15 , Issue 4 , October 1925 , pp. 420 - 433
Copyright
Copyright © Cambridge University Press 1925

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References

page 420 notes 1 Hardy, F., J. Agric. Sci. 1923, 13, pp. 243 and 340.CrossRefGoogle Scholar

page 421 notes 1 Cf., Allison. J. Amer. Soc. Agron. Oct. 1923, p. 409Google Scholar

page 422 notes 1 Von Terzaghi, (Ber. Akad. Wiss. Wien. 1923, 132, p. 105; Sci. Abstr. 1924, 27 A, p. 361), has measured the modulus of elasticity of clays, and has found it to depend on the moisture content.Google Scholar

page 422 notes 2 See Hardy, F., J. Agric. Sci. 1923, 13, p. 243.CrossRefGoogle Scholar

page 422 notes 3 West Ind. Bull. 1912, p. 50.

page 423 notes 1 Manufactured by Central Scientific Company, U.S.A.

page 424 notes 1 Unless the granular soil blocks are prepared by adding water slowly to the sifted soil, swelling causes them to assume a convex upper surface, so that their cross-sectional area exceeds 1 sq. in.

page 426 notes 1 Hardy, F., J. Agric. Sci. 1923, 13, p. 243.CrossRefGoogle Scholar

page 426 notes 2 Mem. Dept. Ag. Ind., Chem. Ser. 6, 3, 03, 1921, p. 163.Google Scholar

page 427 notes 1 Applied Colloid Chem. 1921, pp. 155, 160.

page 427 notes 2 Hardy F., J. Agric. Sci., loc. cit., also Journ. Phys. Chem. (in press).

page 427 notes 3 See Donnan, , Pres. Address, Sect. B, Brit. Assoc. 1923;Google ScholarJ. Soc. Chem. Indus. 1923, 42, 38, p. 900.Google Scholar

page 427 notes 4 Travers and Ray. See Donnan, loc. cit.

page 427 notes 5 Donnan, and Ray., p. 893,Google Scholar who cites Harkins (J. Amer. C. S. 1917, 39, p. 541).Google Scholar

page 428 notes 1 Hardy, F., J. Agric. Sci. 1923, 13, p. 243.CrossRefGoogle Scholar

page 428 notes 2 Trans. Far. Soc. 1922, 17, p. 244.CrossRefGoogle Scholar

page 428 notes 3 Soil Sci. 1924, 17, p. 1.CrossRefGoogle Scholar

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page 428 notes 5 Landw. Vers. Stat. 1904, 59, p. 433.Google Scholar

page 428 notes 5 The now widely accepted views of Hardy and Langmuir suggest that the adsorption of water from its vapour phase by a dry clay, should result in the formation of a monomolecular layer of water over the solid surface. (See Donnan, , loc. cit. and Langmuir, J. Amer. C. S. 1918, 40, p. 1361).Google Scholar

page 429 note 1 See Hardy F., J. Phys. Chem. (in press).

page 429 note 2 The flocculation phenomena of the lateritic soils employed in these investigations are fully described in the article already cited (footnote 1). The siliceous soils behaved normally in that the rate of flocculation of their aqueous suspensions varied directly with lime content. The highly calcareous soil settled from suspension rather more slowly than either of the lateritic soils.

page 430 note 1 See Hardy, F., J. Agric. Sci. 1923, 13, p. 243.CrossRefGoogle Scholar

page 430 note 2 See Bragg, “Discussion on Cohesion,” Brit. Assoc. 1923; J. Soc. Chem. Indus. 1923, 42, p. 930.CrossRefGoogle Scholar Also Donnan, (Pres. Address, 1923, 42 p. 892) who cites Hardy's writings that lead to the conclusion that cohesion forces are essentially chemical in origin.Google Scholar

page 430 note 3 See Cameron, and Gallagher, (U.S. Depl. Ag., Bur. Soils, Bull. 50, 1908, pp. 10–17), for a summary of the early work of Schübler (1838), Haberlandt (1875) and Püchner (1889) on the effect of added substances on the cohesiveness of soils.Google Scholar Also Schurecht, (J. Amer. Ceram. Soc. 1918, 1, p. 201CrossRefGoogle Scholar) for measurements of the effect of electrolytes in increasing the dry strength of clay.

page 431 note 1 Soils, 1918, p. 111.

page 431 note 2 Bechhold, , Koll. Z. 1920, p. 229;Google ScholarC.A. 1921, 15, p. 458;Google ScholarAlexander, , Science, 1921, 54, p. 74;CrossRefGoogle ScholarC.A. 1921, 15, p. 4035.Google Scholar

page 431 note 3 See Moore, Fry and Middleton, , J. Indus. Engin. Chem. 1921, 13, p. 527.CrossRefGoogle Scholar

page 431 note 4 See Hardy, W. B., Fourth Rept. Colloid Chem. 1922, p. 190 et seq.Google Scholar

page 431 note 5 Harrison, , Discussion Rept., Dept. Sci. Indus. Res. 1921, p. 116.Google Scholar

page 431 note 6 Bancroft, , Applied Colloid Chemistry, 1921, p. 73.Google Scholar

page 432 note 1 See Mukherjee, , Discus. Rept. p. 103;Google Scholar also Rosenhain, , “Discussion on Cohesion,” Brit. Assoc.;Google ScholarJ. Soc. Chem. Indus. 1923, 42, p. 932.Google Scholar

page 432 note 2 J. Indus. Engin. Chem. 1921, 13, p. 527.CrossRefGoogle Scholar

page 432 note 3 See Bradfield, , Miss. Ag. Expt. Sta. Bull. 60, 1923Google Scholar. Also. Ries, Clays, 1919, pp 126–128, and Seaele, Third Rept. Colloid Chem. 1920, p. 139 et seq.

page 432 note 4 Comber, , J. Agric. Sci. 1920, 10, p. 425.CrossRefGoogle Scholar