US2176938A - Wall construction and method of making same - Google Patents

Description

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UNITED STATES PATENT OFFICE WALL- CONSTRUCTION AND IWETHOD OF MAKING SAME Walter A. Troy, New York, N. Y.

Application May 12, 1938, Serial No. 207,517

10 Claims.

This invention relates to an improved wall construction, and particularly to a wall construction including a plastered or stuccoed surface characterized by high resistance to cracking when subjected to stresses of compression or tension and by freedom from spalling when nails are driven into it for upporting heavy objects, such as picture frames, works of art and other objects requiring for their exhibition that they be displayed against an extended wall surface.

In art museums, exhibition halls, manufacturers display rooms of various kinds and in private residences there has been a long existing problem of devising a relatively inexpensive wall surface into which nails may be driven to support objects for display and artistic purposes without causing spalling or other damaging or marring of the wall surface and which will permit of the removal of the'nails and the re-location of the object to be exhibited without leaving unsightly broken or marred areas. This problem is particularly acute in museums and the like where itis frequently necessary to drive heavy nails and use picture hooks capable of 25 supporting 100 pounds or more Without cracking of the wall or surface on driving and without failure of the Wall or surface when weight is applied to the nail or hook in the usual way. There is also the further problem that the material of the prior plaster wall constructions tends to spall when the nail is withdrawn.

The most satisfactory material heretofore employed for achieving the desired result hasbeen wood, which has been applied either to a masonry wall or by using an al1-wood construction. The kinds of wood that must be employed are very expensive compared to other building materials such as are employed in practicing the present invention. Heretofore, in the museums which could not afford the more expensive wooden Walls resort has been had to the use of picture molding and practically all pictures, other than light prints, have been suspended therefrom by unsightly wires, rods and other devices that not 45 only detract from the exhibit but are not in keeping with the spirit of modern decorative design.

It has also been proposed to glue fabrics to plaster walls, and this has afforded some help when only small nails and tacks are employed. However, such a wall finish will not support heavy weights and at best the fabric hides the crushed and damaged plaster underneath.

I have found that the above indicated de- 55 ciencies and drawbacks of the wall construcface having characteristics of toughness comt' bined with a measure of resiliency rather than hardness and brittleness, all as more particularly hereinafter described with reference to the attached drawing.

In the drawing there is shown a vertical section of the wall construction of my invention, in which I0 represents a supporting wall of cinder blocks or similar porous material adapted to furnish the desired structural support and at the Asame time having suiiicient porosity to permit of the penetration of nails driven through the superimposed surface coating i2. The coating I2 is made up of one or more, preferably at least two, coats of a plaster or stucco composition having distributed therein a fibrous material adapted to cooperate with the other components in forming a coating that is soft enough to permit driving of nails therein without cracking and that is of low crystalline composition and possesses suilicient porosity or compressibility to insure that the material diplaced by the entering nail will compress against and into adjacent material without rupture of the coating or setting up of undue internal strains. At the same time the composition is so adjusted as to possess sufcient resiliency and strength to resist effectively the stresses of tension and compression that may be expected in the course of normal settling or vibration of the supporting base, or caused by shrinkage of the coating composition in drying and setting. The surface coating is impregnated in its outer surface portions as at I4 with a penetrating liquid or other suitable penetrating agent adapted to impart to the material in the impregnated area additional desirable characteristics of the kind and for the purpose explained below.

A nail driven into a vertical or inclined surface andsupporting a weight behaves as a cantilever beam the maximum shearing force of which is exerted at the surface of the material into which it is driven or embedded. It follows that if thel surface and the material adjacent to it are rendered capable of resisting the shearing force of the nail, the remaining material will not fail. Likewise cracking, spalling and failures of like nature generally commence at the surface and penetrate inwardly. Therefore, if the surface and adjacent material are rendered resistant to such stresses, failures are to a great 'i UO.

25 cement to 2 parts of sand by weight.

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COATING R PLASTIC measure prevented. In impregnating the surface and the adjacent portions of the coating in my wall construction, I aim to impart suflicient rigidity and strength to resist effectively out spalling or cracking.

By way of example, I will describe the invention as applied in forming a wall surface for nailing as in museums, display rooms and the like.

The supporting Wall is laid up with porous nailable blocks, e. g., cinder blocks, in the usual way with mortar. However, before the mortar has set, it is desirable to rake out the joints to a depth of at least 1A" to promote firm anchorage of the cementitious or plaster coating.

The cementitious coating is then made up by rst mixing together in the dry Portland cement and sand previously screened through a 14 mesh sieve in the proportions of 1 part of Portland ry ases os bers are a his mixture in e prop o 1 part to 16 parts of the combined mixture of cement and sand, by weight. A grade of asbestos that I have found to `be very satisfactory is that sold by Johns-Manville Corportion known as Grade 4T, conforming to a guaranteed test identified by the symbol 0 2- 10-4. Suiiicient water is added to form a plastic mix, preferably-frm as stiif as possible and yet capable of being worked and spread with a plasterers trowel or other suitable tool of the masons and plasterers trades.

The surface of the wall blocks previously set is then wetted down and the plastic mixture is applied thereto to form a coating of about 1/2 thickness. 'This coating is allowed to take an initial set after scratching or roughening the surface to facilitate the adherence of the next coating. After not less than 24 hours, the surface of the first coating is wetted down and then a second coating is applied to a depth su'icient to give the two coats a total thickness of about 78". The second or final coat is not scratched but is lightly smoothed on the surface with the trowel or other suitable tool, care being taken not to work to such an extent as to bring too much cement to the surface.

After the second coat has set, but preferably not less than 48 hours, the skin rich in cement brought to the surface by thetrowel is removed by abrasion with steel wool, stiff brushes or the like, to prepare the surface for the final treatment. If the skin rich in cement were not removed it would ultimately become hard, brittle and impervious, a condition that is to be avoided in practicing my invention. Following this last treatment, the wall coating is kept damp for several days and then left to dry or harden for a week or ten days.

After the wall surface prepared as above has dried and hardened, a suitable drying oil is applied to the surface in successive coats their number depending upon the degree of penetration required by the use to which the wall is to be put. For example, five coats will give a penetration of about 1;/8" and impart suflicient strength to insure adequate support for nails required to support weights of around 100 pounds.

After about ten days, the drying oil will have the surfaces of the cementitious coating material in the pores and interstices of the impregnated zone as well as on the face of the wall. Because of the penetration of the drying oil into the same time, the impregnated area is anchored to the body of the surface coating by the asbestos fibers and the nail penetrability of the material is not impaired.

While I have described the invention with reference to the use lof Portland cement as the cementitious ingredient of the coated material, it is to be understood that other hydraulic cements may be used, such as natural cements, slag cements, or any of the various masonry cements on the market. Likewise, the use of other fibrous materials than asbestos to promote the bonding of the cementitious material is not precluded. In fact, any cementitious or plaster composition may be employed that will produce the desired nail penetrability, adherence and strength, and at the same time is capable of surface impregnation with a toughening and strengthening agent.

It will be understood that the proportions of the cementitious and fibrous bonding ingredients may be varied considerably without departing from the invention; for example, when dealing with shorter fiber asbestos or other fibrous material it may be necessary to increase the proportion of this constituent and vice versa.

As is well known, drying oils, in passing to the hardened and toughened state resulting from drying, undergo the chemical change known as polymerization, but the possibility of reactions between acid components of the drying oil and lime or other components of the cementitious material is not to be dismissed. It will be understood that this feature of the invention in its broader aspects is in no sense dependent upon chemical reactions of a specific kind, and the desired penetration and ultimate toughening and strengthening of the surface portions of the coating may be attained in other ways. For example, the penetrating agent may consist of a liquid mixture one or more of the components of which is present for the purpose of imparting fluidity and penerability into the pores of the cementitious or plaster coating, but which evaporates or is otherwise removed from the impregnated layer leaving a solid or semi-solid-residue that serves to effect the desired bonding, strengthening and toughening of the impregnated zone. In addition to mixtures of drying oils and thinners, of which` latter turpentine is a representative example, mixtures of various natural or artificial resins with suitable solvents may be employed. By Way of example, the copal resins, kauri gums, and dammar in admixture with thinners or solvents imparting the desired fluidity and permeability may be used. Appropriate solutions of various cellulose derivatives, such as cellulose nitrate and cellulose acetate will also serve the purpose.

A drying oil that I have found to be particularly useful in effecting the impregnation treatment is raw China-wood oil. The penetrability of the oil and its application may be facilitated by adding thereto a suitable thinner such as 5 any tendency of nails driven into the surface the pores and interstices of the impregnated zone, 5 to shear downwardly through the material when it serves to bond the asbestos fibers and the cea. weight is suspended thereon, while at the same ment-sand mortar associated therewith into a time preserving in the impregnated areas sufstrong, tough integral mass very resistant to ficient penetrability to permit nails to be driven shearing stresses and to cracking when subjected 10 through and withdrawn from the material withto stresses either of compression or tension. At 1o driedand formed a tough strong substance on turpentine. mixture is more watery, is ab- 75- turpentine with highly satisfactory results. EX-

amples of various other drying and semi-drying oils that may be employed are linseed oil, soy bean oil and perilla oil.

arious Mms may be substituted for turpcntine. Furthermore, any of the usual drying agents may also be added when it is desired to further expedite the impregnating treatment.

While the invention has been described hereinbefore with particularreference to its application in situations where it is desired to produce a wall vsurface that is nail penetrable and at the same time adapted to hold a nail firmly in place even when the nail is required to sustain a heavy weight suspended therefrom, it is to be understood that the invention has a wider application in that the non-cracking feature may be employed in many situations where the ability to receive nails and sustain heavily loaded nails is not required. For example, in dwellings of wooden frame construction it has always been a problem to prevent cracking of the interior plas'- tered surfaces. Likewise the cracking of exterior stuccoed surfaces in wooden frame buildings and as well in steel frame constructions is troublesome.

My invention may be employed to advantage in these situations, and when it is not desired that the wall shall be called upon to carry heavily loaded nails, the extent of the surface impregnation may be considerably curtailed, the desired result being effected with a lesser number or even with a single coat of the impregnating agent. In these situations it will frequently not be necessary to build up such a thick coat of the plaster or other cementitious coating as has been described in the specific example. Furthermore, the application of the coating directly to a metal or wooden lath supporting background or other suitable supports, as for example a brick wall, is practical. I claim my invention as applicable in all of these fields.

The impregnated wall surface of my invention may be painted by any oil or other ordinary paint in the usual way.

Where I have used the term plaster composition" in the claims it is to be understood that I have used this term broadly to include not only a plaster as this term is sometimes used technically, but also various cementitious' coating compositions that may be applied by the methods used in the plasterers and masons trade, or by stuccoing. The term plastered wall as used in the claims is similarly intended to include any wall having a plaster composition as above defined applied thereto and possessing the limiting characteristics recited in the claims.

I claim:

1. In a wall construction, a plastered wall characterized by high resistance to cracking when subjected to stresses of compression or tension and by freedom from spalling under impact or when nails are driven into or withdrawn from the same, said wall surface comprising a tough, resilient, nail penetrable plaster composition composed essentially of a hydraulic cement, sand and a fibrous' material and having the outer surface portion thereof impregnated with a l solidified reenforcing agent.

2..In a Wall construction, a plastered wall characterized by high resistance to cracking when subjected to stresses of compression or tension and by freedom from spalling under impact or when nails are driven into or withdrawn from the same, said wall surface comprising a tough, resilient, nail penetrable plaster composition composed essentially of a hydraulic cement, sand and a fibrous material and having the outer surface portion thereof impregnated with a solidified reenforcing agent comprising the polymerized residue of a drying oil.

3. In a wall construction, a plastered wall characterized by high resistance to cracking when subjected to stresses of compression or tension and by freedom from spalling under impact or when nails are driven into or withdrawn from the same, said wall surface comprising a tough, resilient, nail penetrable plaster composition composed essentially of a hydraulic cement, sand and a fibrous material and having the outer surface portion thereof impregnated with a solidified reenforcing agent comprising China- Wood oil.

4. In a nailing wall construction, a supporting base composed of cinder blocks or the like and a surface coating thereon consisting of a tough, resilient, nail penetrable plaster composition, said coating being hardened and toughened in its outer portion by an impregnation of a liquid reenforcing agent.

5. In a nailing wall construction, a supporting base composed of cinder blocks or the like and a surface coating thereon consisting of a tough, resilient, nail penetrable plaster composition,.said coating being hardened and toughened in its outer portion by an impregnation of a liquid reenforcing agent containing a drying oil.

6. In a nailing wall construction, a supporting base composed of a nail penetrable material, a surface coating thereon consisting of a tough, nail penetrable plaster composition composed essentially of a hydraulic cement, sand and a fibrous material,` said coating being hardened and toughened in its outer portion by an impregnation comprising China-wood oil, turpentine and a natural resin.

7. The method of forming a plastered wall surface characterized by high resistance to cracking when subjected to stresses of tension or compression and by freedom from spalling when nails are driven into the same, which comprises forming a plastic mass consisting principally of a hydraulic cement, sand, a fibrous material and water, applying said mass as a coating upon a supporting base, allowing the plaster to set, then removing the outer surface portion of the plaster coating, and thereafter impregnating the surface of said plaster coating with a liquid adapted to solidify in the pores thereof and to harden and toughen the surface layer.

8 The method of forming a plastered wall surface characterized by high resistance to cracking when subjected to stresses of tension or compression and by freedom from spalling when nails are driven into the same, which comprises forming a plastic mass consis'ting principally of a hydraulic cement, sand and asbestos fibers, applying said mass as a coating upon a supporting base, allowing the resulting coating to set, then removing the outer surface portion of said coating, and thereafter impregnating the thus prepared surface with a drying oil.

1'0. In a wall construction, a plastered wall characterized by high resistance to cracking when subjected to stresses of compression or tension and by freedom from spalling under impact or when nails are driven into or withdrawn from the same, said Wall comprising a tough resilient nail penetrable plaster composition having the outer surface portion thereof impregnated with a bonding agent.

WALTER A. TROY.

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