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As a specialist in industrial floor-hardening products, I am responding to a couple of comments in the "Troubleshooting" column from the October 2002 issue. The comments were in reference to specifying limestone as coarse aggregates in concrete floor slabs. In the last paragraph, the column...
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I have been asked to try to match the shades of concrete on a patio and pool deck. The patio was poured about a year before the pool deck. What are my best options for accomplishing this?
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I am looking for a way to calculate the specific surface area (total surface area) of an aggregate that I am using in concrete.
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How can we eliminate the cement balls that we’ve recently discovered in our concrete? This problem seemed to start after we recently installed a new batch controller on our transit-mix plant. Before that, we had operated the plant manually. We’ve always monitored slump and mix consistency closely...
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We are thinking about incorporating self-consolidating concrete (SCC) into our production mixes. These mixes are much more flowable than our traditional mixes. What changes or modifications to our forms will we have to make?
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A participant in Aggregate Research IndustriesÆ Industry Forum (www.aggregateresearch.com/forum) recently posted an interesting question that has challenged our industry since fibers were introduced. The participant started by stating that heÆs noticed a disturbing trend in a recently prepared set...
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One question recently posed on Aggregate Research Inc.Æs Industry Forum (www.aggregateresearch.com/forum) drew a number of interesting and important answers that may help you this season. The questioner wrote: ôIÆve noticed that a variation in ambient temperature can have a big effect on the...
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One of our customers is having a problem with excessive bugholes on the surfaces of walls that are at a 45-degree angle.
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I have an answer for the definition of a C-4 mix (ôDesign Specs for a C-4 Wall,ö February 2002. IÆm working with a concrete contractor who is pouring C-4 for his footings in the morning, setting wall forms, and pouring them with C-4 that same day in winter conditions. What is your opinion of this...
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What is the highest percentage of fly ash that can be used in ready-mixed concrete? Is durability the most important issue in determining the limit?
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I work for the Ohio DOT. I am looking for sources of information where recycled concrete (RC) was used as aggregate in new concrete. Have you used recycled aggregate in new concrete? What was the new concrete used for? What problems did you encounter with recycled concrete as an aggregate?
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IÆm working on creating a mix design submittal based upon a specification that requires closed-gap aggregate gradation. To meet the specification, I need to find, or create, an evenly graded 1 +-inch top size aggregate. This means that the commonly used middle testing sieves, such as the No. 8, No...
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IÆm working with a concrete contractor who is pouring C-4 for his footings in the morning, setting wall forms, and pouring them with C-4 that same day in winter conditions. What is your opinion of this construction process? How will this affect the concrete strength and durability down the road?
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My dispatcher received a phone from a residential neighbor who just had a new driveway placed. ItÆs been stained with various oils from workersÆ construction vehicles. Can we use a 1400-psi washer we use to clean our equipment for this purpose? And after the cleaning is there a sealer this neighbor...
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I am trying to determine R-values for poured-in-place concrete walls, both above grade and below grade, at varying thicknesses. The walls I am working with vary from 6 inches thick for one wall and 10, 12, and 14 inches thick for other walls. (The walls have rebar of various diameters imbedded...
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