US 2542992 A
Description (OCR text may contain errors)
Patented Feb. 27, 1951 NAILABLE CONCRETE Lyle Clapper, University City, Mo., assignor of one-half to Leon B. Schumacher, Kirkwood, Mo.
No Drawing. Application September 10, 1945, Serial No. 615,499
This invention relates generally to concrete and particularly to a concrete article and the batch therefor, which, when set and cured, is
receptivemtcdriven nails and is substantially res is tant to the withdrawal of such nails. ""Maiiy"effdfts have" heretofore been made to provide a concrete into which nails could be driven, but such prior efforts have not met with satisfaction because it was either too hard to receive the nails without bending, or so brittle that the concrete chipped away adjacent to the nails, or so soft that it offered little or no holding power against withdrawal of the nails.
The object of the invention, generally stated, is to provide a nailing concrete, which is not only readily receptive of nails, but offers resistance to the withdrawal of nails comparable to the resistance offered by wood.
This object is accomplished in accordance with the present invention, generally stated, by utilizing, in lieu of the customary fine and coarse aggregates, one aggregate which is flexible enough to yield and receive the nails, together with another a regate which is not only aurasive, but frangible. PW, exfoliated mica is s'atisfac ory, par lcll arly an mulite, such'as a product known n mercia y as onolite concrete a reate. For the frangible a the prouc nown cornmercia y as He dite is preferred. Haydite is a cellular vitrified clay in the form of granules.
Haydite is a commercial product made by burning shale to incipient fusion, cooling, grinding, and grading. It weighs (dry) between 38 and 50 pounds per cubic foot. The grade A size hereinafter referred to is according to the following screen analysis:
Percent retained on screen Percent passing on A screen 953430 Percent passing on No. 16 screen 4 0 Percent passing on No. 50 screen 5-30 Percent passing on No. 100 screen 0-8 2 The batch for the nailing concrete contemplated by the present invention may consist of Portlan ent yieldable aggregate, such as zonflii %oncrete aggregate, and frangible aggre- 5 ga e, such as Haygte, in the proportions of one bag (one cubic foo of Portland cement, one and one-half cubic feet of Zonolite concrete aggregate, three cubic feet of grade A Haydite,
together with from 1 to 1.5 cubic feet of water, depending upon the consistency desired. Such concrete may be mixed, poured, and cured in the same manner and under the same conditions usually followed in the practice of making concrete articles.
Concrete articles compounded in accordance with the batch aforesaid and which, after being poured, cured, and aged for approximately six months, were subjected to nail pull-out tests. The nails were hand-driven with a hammer and pulled out under static loading in the direction of the axis of the nail. Of the several specimens so tested, the average results will be given in the following discussion:
A six-penny common nail having a diameter of 0.111' inch and a length of 2 inches was driven into the concrete for 1.25 inches. The load required to withdraw the nail was 183 pounds corresponding to the holding power of 421 pounds per square inch of contacting area between the nail and the concrete.
A square twisted nail 0.155 x 0.155 was driven 1.75 inches into the concrete article. The average load required to withdraw the nail was 507 pounds, equivalent to the holding power of 468 pounds per square inch.
Galvanized roofing nails having a diameter of 0.145 inch were driven 1.25 inches into the concrete. The average load required to withdraw these nails was 234 pounds, equivalent to a holding power of 411 pounds per square inch.
A shear test was carried out in which oak strips inches x4 inches x 24 inches were nailed with one six-penny common nail driven 1% inches into the flat surface of a concrete article constituged in accordance with the aforesaid batch. The assembly was then stressed in shear. The
average load sustained by such an assembly in shear over the series tested was 530 pounds.
As illustrating variations which may be made in the batch aforesaid, without substantial sacrifice of the receptiveness to nails or the resistance to withdrawal of nails, the content of yieldable aggregate may be reduced to 1.25 cubic feet per bag of cement with concomitant increase of the content of frangible aggregate. such as grade A Haydite, to 3.5 cubic feet.
EXAMINER The content of yieldable aggregate may also be increased beyond the optimum figures first above given with concomitant decrease in the content of frangible aggregate. For example, a satisfactory nailing concrete is obtained from 1.75 cubic feet of Zonolite aggregate per bag of cement with 2.5 cubic feet of grade A Haydite.
In each case, it will be understood that the water content of the batch will depend upon the consistency desired, it being preferred, however, to maintain a water-to-cement ratio of between 8 to 11 gallons of water per bag of cement, which relation is approximately equivalent to 11.5 parts by volume of water to 1 part cement.
Concrete articles poured from any of the batches aforesaid, set and cured in accordance with conventional concrete practice, have a receptiveness to nails comparable to yellow pine and a resistance to withdrawal, when only two weeks old, of more than 100 pounds per square inch. The receptiveness to nails is not substantially changed as the concrete ages. Up to twenty-eight days, the resistance to withdrawal usually increases, but thereafter remains substantially unchanged as the concrete ages. Articles poured of concrete, constituted according to the batches aforesaid, will be found to have a twenty-eight day strength exceeding 1,400 pounds per square inch and will be receptive to nails without fracturing, that is to say, the concrete is not so brittle that it is fractured when the nails are driven into it or when loads of the limits indicated by the test data above are applied to it.
It is obvious, of course, that concrete articles constructed in accordance with the present invention may be reinforced in the manner usually practiced in the art and some dilution of the batch by other coarse and fine aggregates may be tolerated without substantial sacrifice of the nailing properties herein described.
While a disclosure of several embodiments of the nailing concrete contemplated by the present invention have been hereinabove disclosed, it is to be distinctly understood that the invention is not limited to the precise details or proportions of such batches, but that various modifications therein and additions thereto may be made without departing from the spirit of this invention or the scope of the appended claims.
Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:
1. Concrete comprising Portland cement, granules of exfoliated vermiculite, cellular granules of vitrified clay, and water in the proportion by volume of 1 part Portland cement, 1.5 parts exfoliated vermiculite granules, 3 parts vitrified clay granules, and l to 1.5 parts water, said concrete being substantially wholly inorganic, and said concrete when poured, set, and cured being receptive to driven nails and having a resistance to withdrawal of nails driven thereinto of at least pounds per square inch of area in contact with the nail.
2. Concrete comprising Portland cement, granules of exfoliated vermiculite, cellular granules of vitrified clay, and water in the proportion by volume of 1 part Portland cement, 1.25-1.75 parts exfoliated vermiculite granules, 2.5-3.5 parts vitrified clay granules, and 1 to 1.5 parts water, said concrete being substantially wholly inorganic, and said concrete when poured, set, and cured being receptive to driven nails and having a resistance to withdrawal of nails driven thereinto of at least 100 pounds per square inch of area in contact with the nail.
3. A substantially wholly inorganic concrete article composed of 1 part Portland cement, 1.25-1.75 parts exfoliated vermiculite granules, and 2.5-3.5 parts cellular granules of vitrified clay, the cement being hydrated and set, said article being receptive to driven nails, and having a resistance to nails driven thereinto of at least 100 pounds per square inch.
4. A dry batch for nailing concrete comprising 1.25-1.75 parts exfoliated vermiculite granules, 2.5-3.5 parts cellular granules of vitrified clay, and 1 part Portland cement.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,314,772 Viens Sept. 2, 1919 1,637,935 Garza Aug. 2, 1927 1,927,102 Sucetti et al Sept. 19, 1933 1,971,900 Cereveny Aug. 28, 1934 2,005,069 Bermier June 18, 1935 2,037,294 Williamson Apr. 14, 1936 2,043,249 Jones June 9, 1936 2,377,491 Goodrich June 5, 1945