File:A practical treatise on natural and artificial concrete; its varieties and constructive adaptations (1879) (14760685751).jpg

Identifier: practicaltreatis00reid (find matches)
Title: A practical treatise on natural and artificial concrete; its varieties and constructive adaptations
Year: 1879 (1870s)
Authors: Reid, Henry
Subjects: Concrete
Publisher: London, New York, E.& F.N. Spon
Contributing Library: Getty Research Institute
Digitizing Sponsor: Getty Research Institute

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d in accordance with the quantity of mixturesupplied and the velocity of the beaters or tamper. Unlessthis combination of supply of the material and its conversionby the machinery is regulated with almost automatic accuracy,it is obvious that irregularity in the tamping or overfeedingof the revolving mould would result in an imperfectly im-pacted mass, and any pipes so fabricated would be faultyin character and deficient in strength. Besides this dis-advantage, another equally dangerous one in its results is anoverdose of moisture. An excess of water would render thebeneficial action of the impinging tamper inoperative, as theblow therefrom could not consolidate an overwetted mass,owing to its spongy character. For two reasons, therefore,it is imperative that great care should be bestowed on thispart of the process, for too much water would result in aporous pipe and the imperfect tamping weaken its tensileand compressive value. The moulds are allowed to stand for a certain time (from
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Pipe-moulding Machine. 232 A PBACTIOAL TREATISE ON CONCRETE. one to three days, according to the state of the weather), andwhen the casings of the moulds are removed, the pipe istaken at once to a reservoir of water, in which it remainsuntil considered sufficiently matured to be stored withoutrisk of fracture in the yard. Until recently the rock-concrete pipes were treated asthus described, but owing to the pressure of the trade, andthe impossibility of holding them in suffiicient quantitiesuntil the proper natural induration had been realized, theprocess of silication is now resorted to. The plan adoptedfor this purpose is that of the Victoria Patent Stone Company,from whom a license to use their process had been obtainedby Messrs. Henry Sharp, Jones, and Co. Figs. 3 and 4 on Frontispiece show sections of rock-concrete material, the following being an analysis of its chemical value: — Water of combination 6 • 80 Oxide of iron and alumina 515 Lime 17-02 Soluble silica 12-95 Insolu

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