The American Concrete Institute has released the new ACI 301-20, Specifications for Concrete Construction, along with the companion ACI Field Reference Manual.
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Concrete temperature monitoring becomes more critical in cold weather as low temperatures decrease the rate of strength development affecting the durability of the structure. For this reason, accurate and consistent temperature readings of concrete elements are important so that the quality of the structure is optimized.
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The American Concrete Institute (ACI) awarded Ahmad (Amir) Shahroodi, a student at the University of Ottawa, for his paper on non-destructive testing (NDT) of concrete structures. Shahroodi, who is working toward his doctorate in civil engineering, is a concrete materials and durability specialist.
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Pavement engineers, who deal with many of the same issues faced in the concrete-floor field, do not talk much about joint stability or differential movement. Instead, they talk about load-transfer efficiency—a related but distinct property. Whenever a load is applied to one side of a joint, it creates stress on the loaded side. Load transfer occurs when some of that stress gets transferred to the unloaded side. Load transfer efficiency (LTE) is a measure of how well the joint shifts stress to the unloaded side.
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A stable joint—one that does not move excessively when a load is applied near it—is obviously better than an unstable one. However, the best methods to make joints stable are not always agreed upon. For example, one floor designer might call for stout, closely spaced dowels, while another also chooses dowels, but makes them thinner and spaces them farther apart.
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For as long as anyone can remember, the construction industry has used the word ‘waterproof’ to describe construction materials. People commonly refer to something as being waterproof if it holds water in or out and does not leak. However, the word waterproof is technically not defined this way. Most dictionaries define it as being impervious to water, that water cannot penetrate it at all. This raises a serious question: Can anything really be completely impervious to water?
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