Frequently, shotcrete contractors are required to shoot test panels at the beginning as well as throughout projects. Several tests are performed from these panels; however, compressive strength testing is the most common. This article will primarily address compressive strength testing. At some point, every contractor has missed a required break strength on a core extracted from one of their panels. Frequently, those bad results are not caused by bad material or poor workmanship. They are caused by poor test panel handling and improperly performed test standards. Often, the causes of those bad test results could have been easily avoided. Let’s discuss some of the more common test panel mistakes witnessed in the field
I live in a 10-story condo building built in the 1960s. The entire building is made of gunite. We use masonry drill bits for holes, but nothing seems to grip well. We have tried concrete screws, metal drywall anchors (which seem to work the best), and a plethora of other anchors and screws, but nothing seems to work. They all cause mushrooming and they either don’t grip or turn the wall to powder. What are the best tools to affix things to the walls?
Shotcrete is a placement method for concrete. Dry-mix shotcrete (the old tradename is gunite) using proper materials, equipment, and application techniques should have easily been able to reach a strength of 4000 psi (28 MPa) in the first month. After 10 years in-place the concrete should be even stronger. The level of concrete strength developed by quality shotcrete should easily accommodate drilling in anchors or concrete screws. In my experience it would have been highly unusual to build an entire 10-story building with shotcrete even in the 1960s. I’d suggest based on the extremely weak material properties and the wall turning to dust what you think is shotcrete may be sprayed plaster or stucco. Those materials don’t have near the same strength as shotcrete and would exhibit many of the problems you have mentioned.
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Kiewit Infrastructure Company
470 Chestnut Ridge Rd , Woodcliff Lake NJ, 07677-7604 United States
Knowles Industrial Services Corp.
295 New Portland Rd, Gorham, ME 04038-1867, United States
Knowles Industrial Services Corp.
295 New Portland Rd, Gorham ME, 04038-1867 United States
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Mapei Corporation, UTT
167 Judson Avenue , Bristol CT, 6010 United States
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Maple Site Solutions Inc.
766 Old Hespeler Road , Cambridge Ontario, N3H 5L8 Canada
Marubeni Specialty Chemicals, Inc.
10 Bank St White Plains, NY 10606-1933 United States
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Master Builders Solution US, LLC
3519 SW California , Portland OR, 97219 United States
Mays Construction Specialties Inc
2399 Riverside Parkway, Grand Junction CO, 81505 United States
Miller & Long Co, Inc
7101 Wisconsin Ave Ste 800 , Bethesda MD, 20814-4827 United States
Mosites Construction Company
400 Mosites Way, Suite 100, Pittsburgh, PA 15205, United States
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