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.
The ASA Buyers Guide provides a detailed listing of the products and services offered by our Corporate Members.
Sustaining Member
Lanford Brothers Company, Inc.
122 N Commerce Street P.O. Box 7330, Roanoke VA, 24019 United States
Limen Group Const. (2019) Ltd
135 Commerce Valley Drive East, Markham ON, L3T 7T4 Canada
Sustaining Member
MacLean Engineering
300 Raglan Street, Collingwood ON, L9Y 5R2 Canada
Sustaining Member
Madison Concrete Construction
130 Quaker Lane, Malvern PA, 19355 United States
Sustaining Member
Mapei Corporation, UTT
1144 E Newport Center Drive, Deerfield Beach FL, 33442 United States
Marubeni Specialty Chemicals, Inc.
10 Bank St White Plains, NY 10606-1933 United States
Sustaining Member
Master Builders Solution US, LLC
23700 Chargrin Blvd, Beachwood OH, 44122 United States
Mosites Construction Company
400 Mosites Way, Suite 100, Pittsburgh, PA 15205, United States
Sustaining Member
Nationwide Shotcrete Inc
23638 Lyons Ave, Ste 273, Newhall CA, 91321-2513 United States
Neuman Pools Inc
W9684 Beaverland Pkwy, PO Box 413, Beaver Dam, WI 53916, United States
Normet Americas Inc
1414 S.Gladiola Street, Ste 100, Salt Lake City UT, 84104 United States
Sustaining Member
Ocean Rock Art Ltd
40141 Diamond Head Road, Squamish BC, V8B 0G2 Canada
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