GB278788A - Improvements relating to the preparation of organic materials or aggregates for use with cements - Google Patents

Abstract

278,788. Garrow, J. R. July 7, 1926. Concretes.-Organic material such as wood, sawdust, shavings, coir, sizal or other fibres, or paper pulp, for use as an aggregate with cement, concrete, &c., is prepared by subjecting it to the combined influence of heat and moisture so as to cause it to expand or dilate to the maximum, or above the maximum, degree of dilation to which it will be subjected in service, and then stabilizing the treated material by causing a substance adapted to act as a support or filler and to maintain the material in its expanded condition to be deposited in the pores or cells of the material. The material is treated, for instance, with a liquid at temperatures of from 120‹ to 220‹ F., preferably at or somewhat above atmospheric pressure. The expanded material may be maintained in its dilated condition by means of a solute introduced in solution and subsequently by physical or chemical means converted into a solid, for instance by deposition from solution on cooling, or by reaction with a second solution to form a precipitate. In the first case. a solution of three per cent of lead chloride may be used, or other solutes such as barium ferrocyanide, barium hydrate, ferric phosphate, oxalic acid, magnesium phosphate, calcium borate, or uric acid. Two or more of these compounds may be used, provided that no harmful reaction takes place. In the second case, treatment with a hot solution of lead chloride may be followed by treatment with a solution of a soluble sulphate or chromate such as zinc sulphate or potassium sulphate or chromate. Other compounds used in the first stage may be aluminium chloride, sulphate, acetate or soluble aluminates; barium hydrate, chloride or ferrocyanide; calcium chloride, borate, nitrate or hydrate; copper sulphate, chloride or acetate; chromium sulphate or chloride; lead acetate, chloride nitrate or soluble plumbates; magnesium sulphate, chloride, phosphate or nitrate; mercury chloride, nitrate or sulphate; iron acetate, bichromate, chromate, chloride, oxalate, or sulphate; potassium or sodium resinate, palmitate, oleate, bichromate, sulphate, chloride, ferricyanide or ferrocyanide; zinc chloride, nitrate, sulphate, or soluble zincates. Mixtures of two or more of these salts may be used. Appropriate reagents to combine with these salts are used in the second stage; for example if barium hydrate is used in the expanding solution, zinc sulphate may be used to produce barium sulphate, and zinc hydrate in the pores of the material. The strengths of the solutions may vary, but 3 per cent to. 10 per cent solutions give satisfactory results. The compounds produced in the material should preferably be without loosely combined water of hydration or crystallization; suitable compounds are calcium carbonate, oxalate, phosphate, borate or chromate; barium sulphate, carbonate chromate, hydrate or ferrocyanide; lead carbonate, chloride chromate or sulphate; magnesium carbonate or phosphate; copper carbonate, oxalate, chromate or ferrocyanide; or mixtures of these substances. Either of the reacting compounds may be used in the solution in which the material is first expanded. Salts may be selected which have a preservative action on the material, or preservative substances may be added. For example, when lead chloride is used, an addition of ¢ to 4 per cent of mercuric chloride may be made. A salt of high osmotic pressure, such as calcium chloride, may be added to the solution used to expand the material.