Excerpt from Proportioning Concrete Mixtures and Mixing and Placing ConcreteIt is also well to avoid piling sacked cement directly against the side of the shed, as dampness may pass through the side walls. A properly built concrete storage shed or warehouse, will be air and moisture-proof, and is best for cement storage. Cement which has become caked or hardened as a result of absorbing moisture must not be used in concrete mixtures. If the lumps may be crushed readily under slight pressure between ones fingers, the cement has not been damaged. Such lumpiness is usually the result of what is called storage caking and is common in the lower sacks of piles owing to the weight of the sacks above.AggregatesMany persons disregard the importance of carefully selecting the sand, pebbles, and broken stone, or other materials which are sometimes used in their place, when preparing concrete mixtures. Sand and pebbles or broken stone, when used in concrete, are referred to as "aggregates." Sand is known as "fine aggregate," while the pebbles and broken stone are called "coarse aggregate." Sometimes clean stone screenings below a certain maximum size, that is, ranging from ¼ inch downward and free from dust, are used as fine aggregate instead of sand.In order to distinguish between sand and pebbles, that is, between the fine and the coarse aggregate, it is necessary to fix a maximum size for the material that is to be called sand and a minimum size for the pebbles or broken stone. In concrete work, sand is the material that ranges in size downward from ¼ inch in greatest dimension, while pebbles or broken stone range in size from ¼ inch upward.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis 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.
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