. A practical treatise on natural and artificial concrete; its varieties and constructive adaptations . daily from the mixtures of the concrete in processof conversion. By this means not only is the proper qualityof cement secured, but a constantly recorded tensile historyof the actual strength and quality of the concrete itself. Insoluble siliceous matterOxide of iron and aluminaMagnesia and loss 97-601-970-43 100-00 ENGLISH CONCRETE INDUSTRIES. 229 In fact these apparently trivial details are scrupulously-attended to, and no pipe is made without a reliable andaccurate test of its value, so t
. A practical treatise on natural and artificial concrete; its varieties and constructive adaptations . daily from the mixtures of the concrete in processof conversion. By this means not only is the proper qualityof cement secured, but a constantly recorded tensile historyof the actual strength and quality of the concrete itself. Insoluble siliceous matterOxide of iron and aluminaMagnesia and loss 97-601-970-43 100-00 ENGLISH CONCRETE INDUSTRIES. 229 In fact these apparently trivial details are scrupulously-attended to, and no pipe is made without a reliable andaccurate test of its value, so that at any future time, onreferring to the date and number on the pipe, its tensile valueis readily ascertained. The proportions now used are threeof well washed and properly balanced aggregate with one ofthe best Portland cement, The use of machinery for mixingis resorted to, thus ensuring accuracy of amalgamation, in-cluding the necessary moisture, before entering the mouldingmachinery. The mixer used for this purpose is as shown byFig. 30. The water is imparted to the hand-proportioned Fig. Mixing Machine. mixture of cement and aggregates by a carefully arrangedjet under the immediate control of the workman in chargeof this machine. It is most important that the proper andexact quantity of water should be carefully imparted to themass, otherwise the desired quality of density in the concreteis unattainable. Experience in the use of the American moulding machine 230 A PRACTICAL TREATISE ON CONCRETE. and its various mechanical appliances indicated that the bestquality of work was not reached by its aid, and accordinglyfrom time to time improvements have been effected, culminat-ing in a new machine patented by Messrs. Henry Sharp, Jones,and Co. Two of these machines have now been at work forsome time, and the improved quality of work which theyturn out clearly indicates a considerable advantage over theoriginal American one. The moulding machine is shown byFig. 31, and con
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Keywords: ., bookcentury1800, bookdecade1870, bookpublisherlondo, bookyear1879
