Using most masonry fasteners can be such a hassle. First you drill a clearance hole in the lumber, then a hole in the masonry for the anchor sleeve, (meanwhile making sure everything is still lined up). Finally, everything comes back apart so you can drop the anchor sleeve in the hole. Hopefully, the sleeve will grab when the screw is tightened.These great new concrete screws don’t use any type of anchor sleeve at all. In fact, all you do is drill a hole into the concrete through the part you are anchoring and drive the screw. Because of the special thread pattern and extra hard steel, the screw cuts its own threads in the concrete. These screws aren’t just painted for looks. Their color comes from a special epoxy coating, so they pass a 25 cycle Kesternich corrosion test with less than 15% red rust! Give them a try - they are perfect for attaching framing lumber, electrical boxes, brackets, or almost anything else to concrete.
CONCRETE SCREW ENGINEERING DATA
Pittsburgh Testing Laboratory tested the 1/4" concrete screws for both pull-out and shear in two grades of structural concrete using 2-3/4" long screws embedded to a depth of 1" in a 3/16" drilled hole. Tests for pull-out and shear were repeated three times for both concrete grades. Test values for other materials will be different.
|Test: Pull-out Load (lb)
||Shear Load (lb)
Independent testing of the 3/16" masonry screws was performed in a similar manner in 3,725 psi hard rock concrete. The pull-out values shown below are the average for ten tests:
|Pull-out Load (lb):
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