| CONCRETE CONSTRUCTION Online: The latest in construction methods, materials and equipment for concrete contractors and specifiers, including commercial, residential, and decorative concrete resources. |
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August 24, 2010
Self-DelusionThe dozen biggest recurring slab-on-grade problems—both real and imagined—involve: cosmetics, cracking, curling, delamination, dowel alignment, profile tolerances, joint filling, joint stability, joint spalling, sweating, thickness, vapor transmission, and WWF location. Both owners and designers, of course, presume the science embodied in the established design and specification procedures is capable of avoiding all these troubles. Indeed, so the thinking goes, if the contractors would just follow the plans and specs then everything would be fine. ... Posted By: eciaglia | Time: 5:29:00 PM | Permalink and Comments (0 Total) August 24, 2010
As Simple as 1-2-3A level shovel of cement, two full shovels of sand, three full shovels of stone, enough water to make it workable, and voilà—the magic stuff around which the concrete profession revolves. My granddaddy's 1-2-3 concrete formula—passed on to me around age 12—was my introduction to the high-tech world of concrete. Fifty years later, most slab-on-grade projects feature some variation of this mix. ... Posted By: eciaglia | Time: 5:26:00 PM | Permalink and Comments (0 Total) August 10, 2010
Curl NumbersRule No. 8a asserts the futility of using the compressive strength and slump tests to control the quality of a slab on grade. Because these two concrete characteristics are irrelevant to a slab's performance, their management can provide little if any benefit.... Posted By: eciaglia | Time: 9:11:00 AM | Permalink and Comments (1 Total) May 04, 2010
Check Your AnswersAll 40 statements in April's Pop Quiz are false. If you answered "true" to some (or even many) of them, please don't feel too badly. Though the wording was straightforward (I promised no tricks), many of the statements were chosen precisely because they are so generally accepted as being true—especially those concerning slump, shrinkage, cracking, and curling. Future columns will address many of these all-too-common fallacies in some detail, and hopefully will provide a much clearer understanding of what actually is happening. If you aced the test, congratulations! You may skip the next dozen or so installments. On the other hand, if your score was less than perfect, I think that you will find what comes next very interesting. ... Posted By: eciaglia | Time: 12:50:00 PM | Permalink and Comments (4 Total) April 08, 2010
A Pop QuizThe first six installments in this series dealt with contracting issues. Now we change gears to focus on the physics of the slab on grade. For starters, the following true or false quiz should give you a fair sense of your current technical level. The context is slabs on grade, and there are no tricks. Take your time and use references if you like. When you're ready, check your answers.... Posted By: eciaglia | Time: 3:15:00 PM | Permalink and Comments (4 Total)
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