Radford's Cyclopedia of Cement Construction Volume N . 1; A General Reference Work on Up-To-Date Practice in the Manufacture and Testing of Cements the Selection of Concreting Materials, Tools, and Machinery the Proportioning, Mixing, and Depositing of Co (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1910 Excerpt: ...from any dealer in chemicals, or in large quantities from manufacturing chemists. A 10 per cent solution is obtained by dissolving 8 pounds of calcium chloride in 10 gallons of water. Artificial stone made in this way will harden, and can be removed from moulds or forms, in one-third the time required when only water is used for mixing. The chemical is said to have no injurious effect whatever on the strength or soundness of the cement. DEPOSITING CONCRETE Concrete should not be allowed to stand unused for any considerable length of time after being mixed, but should be placed or deposited at once. In no case should this be delayed beyond 20 to 30 minutes after the cement is first wet. Effect of Remixing. To disturb the concrete after it has begun to set, will not only retard its setting, but may possibly prevent the development of its full, ultimate strength. This is particularly true where the cement is to be used in reinforced work, as remixing reduces the adhesiveness and binding power of the cement. If it is permissible to wait a long time--say several months--for the development of the full strength of the concrete, remixing of both Portland and natural cement mortar and concrete might be allowed, if done shortly after initial set has begun--say within an hour or two; but if, as is usually the case, it is desirable that the mixture shall acquire its full strength within a few days or weeks, then cement mortar or concrete which has begun to set before placing should be rejected. If the mixing process is kept up for about two hours continuously before placing, it has been found that the strength of the mixture will be considerably increased, this being due, in all probability, to the more thorough blending and interpenetration of the constituents of the...