
ET
Jan 10, 2004, 10:58 AM
Post #6 of 10
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Re: [Rolly] Building Project Update for 8 January 2004
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....The things I noticed in all of them are a casual attitude toward following the dimensions shown on the drawings and a total lack of interest in using a square. The result is we have irritating errors in sizing and locations of some walls and windows as well as corners than aren't square. Many of the non-square problems would be unnoticed if we had carpet on the floor, but tile really points up the errors.... Interesting! I've noticed the careful installation of small pieces of tiles to fill in gaps between a full tile and the wall, and marvelled at the attention to detail. It never clicked on me that this is probably the root cause problem. It's also consistent with the idea that construction practices change in a place where labor makes up smaller percentage of total construction costs and you can afford to have somebody carefully scribing, cutting, and installing tile fragments.
....TThe problem that really worries me is the concrete work on beams and columns. In the USA, and probably most other countries, concrete pours are vibrated to be sure there are no voids. I have never seen a vibrator being used here. We had a guy with a piece of rebar jabbing into the pour. And that only because I insisted on it. Even so we ended up with columns having voids and poor joints. I nearly had a stroke when I saw one corner column with a two foot gap in the concrete...... And more enlightenment! I've noticed voids and spalling, as well as what appeared to be much faster aging and deterioration of concrete work. After reading your pages sort I sort of chalked up to casual mixing and contamination, but this would play a major factor. People are going to love it when during my next visit I go climbing up next to failing concrete to better examine the exposed edges..... I have seen a pretty frightening concrete failure on a large construction project in the US. With all of the carefully spec'd out mix and additives, drawings, and equipment, I saw the results of an underwater pour where the crew got lazy (it was the last couple of columns for the day, and no inspector could get to the site without being spotted about half a mile away) and pumped the concrete from too high up, allowing the concrete to fall through the water within the form, rather than pumping it to the bottom and moving upwards. When the forms were removed a few days later, a couple of the columns crumbled dramatically, as the cement never properly set (and in some areas completely washed away) and the aggregate sorted out by size as it fell through the water. The contractor's insurer ended up paying of a very expensive demolition job, as well as the cost of the replacement construction and pours.
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