Adding Up Admixtures
by Paul Tarricone, Asst. Editor;Serial Information: Civil Engineering—ASCE, 1992, Vol. 62, Issue 5, Pg. 48-51
Document Type: Feature article
Abstract:
The importance of preventive maintenance and lifecycle costs has put added emphasis on concrete performance. For many specifiers, chemical admixtures, added to concrete at the batch plant, can be the answer. Although they can add anywhere from $10 to $40 per cubic yard to the up-front cost of concrete, these chemicals can improve the material's workability, flexibility and strength, while enabling construction crews to meet scheduling demands, pour concrete in bitterly cold or blistering-hot weather, and achieve higher project quality. For instance, durability is key today. Owners want concrete that is virtually impervious to deicing salts and harsh marine environments. One solution is combine admixtures such as silica fume and a corrosion inhibitor in the same batch. Admixtures also are being developed for, or used in, concrete that must perform in particularly demanding environments. The U.S. Army Corps of Engineers is researching antifreeze admixtures in its cold regions lab and anti-washout admixtures can improve underwater concrete pours for locks, dams, etc. However, admixtures should be used wisely and judiciously, according to experts. Many emphasize the importance of testing trial batches, before a project starts, to address the possible compatibility problems between admixtures, which can cause a chemical war within the concrete. Educational efforts are also being sponsored by TRB and FHWA.
Subject Headings: Concrete admixtures | Concrete | Chemicals | Strength of materials | Project management | Federal government | Construction materials
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