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[SEAOC] Re: [SEAOC] Re: [SEAOC] Concret cracks[Subject Prev][Subject Next][Thread Prev][Thread Next]
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- Subject: [SEAOC] Re: [SEAOC] Re: [SEAOC] Concret cracks
- From: SCHFUN(--nospam--at)aol.com
- Date: Thu, 19 Sep 1996 14:02:16 -0400
I usually answer the question of "Did the earthquake cause these concrete cracks ?" by evaluating other possible reasons for the cracks, such as: 1) are the soils expansive enough to cause the cracks? (what is the soil expansion index, thickness and reinforcing of the slab, sources of soil moisture) 2) What about tree roots? I've seen alot of slabs heave and crack near trees with large, surface roots. 3) What is the age of the concrete slab? How many seasonal cycles of wet/dry, hot/cold have the concrete and soil been exposed to? 4) What is the orientation and width of the cracks, do they have vertical offsets? Vertical offsets may indicate soil settlement, rather that earthquake movement. (What about settlement caused by the earthquake?) I also look at paint lines, past patching of cracks, and any other evidence for the age of the cracks. If there are other, plausible reasons for the cracks, then the liklihood that they were caused exclusively by the earthquake is lessened, in my estimation. The bottom line, though, is that it is very difficult to determine conclusively whether a particular slab crack was caused by earthquake or any other cause. Too bad we can't get pictures the day before the earthquake, and compare them to pictures taken the day after the earthquake. Steve Helfrich, GE ...
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