This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 edition. Excerpt: ... chapter xviii. qualities of concrete blocks. F1rst in importance of the qualities of concrete blocks is that freedom from cracks, deformation, and disintegration which cannot be better defined than by the comprehensive word " soundness." Whatever be the other qualities of a block, it is valueless without soundness; whatever be its defects, it is good for something if sound. It is scarcely necessary to say that a first requisite of a sound block is a sound cement. Of this matter enough has been said in the chapter on Cement. Of the quantity of cement it may be added, to what has already been stated in the chapter devoted to Proportioning and the chapter on Voids, that the cement must thoroughly coat the aggregate in order to exercise its cementitious or bonding function, which is so essential to a sound concrete block. The matter of mixing also has a direct action upon the ultimate quality, and that in the respect last mentioned. It is in the handling and curing of blocks after manufacture, however, that unsoundness is most often developed. In transferring blocks to the racks, cars, and curing-yard, latent defects and invisible cracks are developed which ultimately cause the loss of the entire block, or, if a rigid inspection of the finished product be omitted, may result in failure of the member in time of need. It should be remembered that a crack in a freshly made block never heals, but rather tends to extend through the block. Hence too much care of green blocks cannot be exercised, and the slightest defect should cause the block to be immediately returned to the mixing-platform, or, if the cement has already set, it should go to the scrap-pile. In curing, lack of uniform conditions of moisture and shade, as well as air-drafts, are...