Excerpt from Method of Proportioning Concrete Materials, Screened and Unscreened Gravel The making of concrete is essentially a manufacturing process, but it suffers under the handicap of having no fixed plant location since the concrete must usually be made at the site of the structure. It is further more a chemical as well as a mechanical process, and is subject to various disturbing influences on that account. The factor that has had the most to do with the growth of the concrete industry and also with its slowness of scientific development has been the fact that anyone could take some cement, water, sand and stone, mix them together and get a. Substance that would set and harden. The job was so easy, it took a long time to establish the fact that most con crete so made was a very inferior article. That so much successful concrete work has been done in spite of poor methods is evidence of the value of the material. The basic requirements for the manufacture of concrete are today well established, and failure to make at least sound concrete is inexcusable. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.