US2340535A - Building material - Google Patents

Description

106. composmons, p I Examiner COATING 0R PLASTIC Cross fl0 Feb. 1, 1944. P. w. JENKINS 5 BUILDING MATERIAL Filed Oct." 12. m9

EXPANDED -VERMICULITE MINERAL PLASTIC BINDER ACOUST'CAL FACING LAYER INVENTOXIZ; P ns fi wkw,

Patented F ob. l, 1944 BUILDING MATERIAL Paul W. Jenkins, Pittsburgh, Pa.,

H. H. Robertson Comparga assignor to Pittsburgh, Pa., a

corporation of Pennsylva Application October 12, 1939, Serial No. 299,139

2 Claims.

This invention relates to a building material and more particularly to a slab or tile.

In general, the object of the invention i to provide a novel and highly eflicient slab or tile which may be used with advantage in the fireproofing of steel load supporting members such as steel floors and also to provide an acoustical covering or-surface for the interior of the building.

With this general object in view and such others as may hereinafter appear, th invention consists in the composite tile possessing emcient fireproofing and acoustical characteristics hereinafter described and particularly defined in the claims at the end of this specification.

The drawing illustrates acomposite tile embodying the present invention, Fig. 1 being a vertical cross section and Fig. 2 a side elevation with a portion broken away.

For purposes of illustration, the invention will be described a embodied tection for the undersurfaee of a metal floor in order to provide a floor with the requisite fireproofing to enable the same to comply-with the regulations usually required in the construction of fireproof and fire resisting buildings in this country. The surface of the tile which is to comprise the under or exposed surface after erection is provided with an acoustical layer formed as an integral part of the tile enabling the fireproofing tiling to serve as an efficient acoustical ceiling, reducing to a minimum the cost of fireproofing the steel floor and providing the desired acoustical treatment. Heretofore, with any of the fireproofing tiles upon the market and with any of the acoustical tiles upon the market, duplicate operations have been required to fireproof such a steel floor and to provide the desired acoustical treatment for the interior of the building beneath the floor. The major part of the cost in both operations has heretofore been chargeable to sales, handling, installations and the like, and the duplication of many of these charges has caused the total erection expense to exceed a practical amount. The present invention contemplates a composite tile comprising a body portion of noncombustible material preferably comprising expanded vermiculite and gypsum plaster and a thinner facing layer prising preferably of acoustical material comamineral acoustical material "F l s of which several are now on the market, as will be described. The acoustical layer is bonded to the body portion of the tile during the manufacture of the composite tile so that on the job the single composite tile may be erected to provide the desired fireproofing for the steel floor or other load supporting member of the building and at the same time the acoustical facing serves to provide the required acoustical treatment for the portion of the building below the floor. The gypsum tile, heretofore commonly used for fireproofing purposes, has one inherent undesirable feature which I attribute to the dehydration of the gypsum when such a tile is exposed to fire conditions. As a result of the dehydration process, the resulting dehydrated gypsum body possesses very little strength and in addition, during the dehydration, a characteristic tendency exists for fissure cracks to develop through in tile applied as a pro-,-

' such as a gypsum the body of the tile. In practice, the employment of a tile of a thickness substantially greater than that required for adequate thermal insulation in the protection of the steel fioor or other member has been resorted to in order that sufficient strength may b obtained in the the after the latter has been exposed to a fire condition.

I have discovered that expanded vermiculite when incorporated into a mineral plastic binder plaster and the composition molded into slab form, has the elfect of substantially eliminating volume change during the dehydration of the gypsum when such a tile is exposed to fire conditions and as a result, the completely dehydrated tile retains a considerable measure of its strength. This result is apparently due to a reaction between the gyp um and the vermiculite or it may be due to some vitrification of the vermiculite although at present I am unable to state the exact reason for this result. Experience has demonstrated the ability of such a gypsum and vermiculite composition to retain its strength when exposed to fire and this feature may be utilized in practice to enable thinner sections of tile to be employed as a fireproofing with safety.

Tests on slabs or tiles made with different weight ratios of expanded vermiculite to gypsum V plaster have shown that the requirements for satisfactory commercial fireproofing of steel building members are bestsatisfied with a composition within the range of from 2:4 parts by weight of gypsum binder to 1 part by weight of expanded vermiculite. Compositions containing less than 2:1 ratio are somewhat deficient in the strength required for economical handling and application and do not retain sufiicient strength during fire exposure to insure of their remaining in place as cover without added reinforcement. Compositions containing an appreciably greater ratio of binder than 4:1 tend to exhibit undue shrinkage and deformation during fire exposure. these efiects tending to destroy the continuity of the cover. It will be understood that all reference to the performance of expanded vermiculite-gypsum refer to compositions within Emma! Wood fibered miculite ypsum in e plaster tile Std. gypsum fircproollng tile Weight in lbs. per per sq. ft.; 1" thick 4. 27 7. 56 5. 28

Volume shrinkage after 3-hr. exposure percent.. 0.5 4.7

Ratio of strength after exposure to g initial weight. 700 1 68 0 Maximum tempeb a ature reached Dislntegrated this preferred range although it is not intended gmfff t i 1,096 1.318 1,242 that the ideas involved be limited to the use of Average temperathe materials within this range. 1 gfi gg fgfi The claimed superiority of the expanded ver- 1st to end of 3d miculite-gypsum compositions in the form of tiles, slabs, and the like is illustrated in thefollowingj paragraphs by direct comparison with other gyp 1 sum compositions commonly employed for the purpose. v

Gypsum fireproofing tiles and slabs are widely used in fire-resistant construction as covering for building members subject to damage by fire exposure. The following examples, taken from a list of generally acceptable coverings for steel members in fully-protected construction are offered in illustration:

Steel beams, girders, and trusses Two inches or more solid precast gypsum unit's, well anchored or bonded, plastered with j at least inch plaster. r

Floors and roofs Floor construction consisting of 2 inches or more top slab of poured or precast gypsum on standard steel channels and bottom slab of 2 inches or more poured or precast gypsum, plastered with at least inch gypsum plaster.

Commercial gypsum products universally employed for such use as above are composed of hydrated gypsum plus a relatively low percentage of reinforcing fiber (generally wood fiber). They owe their fireproofing eificiency mainly to the fact that heat is absorbed in driving off and vaporizing their contained water of hydration. The progress of thisdehydration through the body of the cover upon exposure to fire is accompanied by shrinkage and the development of characteristic fissure cracks in the dehydrated layer. These efiects detract from the thermal resistance of the cover, and when dehydration is carried to completion, limit the performance of the cover as protection. It is necessary to employ a suflicient thickness of such material to insure against this action (dehydration) going to completion in the time interval for which protection is required. According to the above samples, this thickness may be 2 inches when an additional inch of gypsum plaster is pplied. I f Fire tests have demonstrated the ability ofexbanded vermiculite-gypsum compositions to withstand fire exposure without cracking, without I The "gypsum compositions used in the above 3 comparisons are classed among'the most efficient excessive shrinkage in volume, and without danner. sections of cover than are required in the fireprooflng materials available in terms of weight and thickness of cover required. While the performance characteristics of other commonly used fireproofing materials will differ from those of the gypsum products, it can be shown that all these materials are inferior in tileform to the expanded vermiculite-gypsum compositions, particularly in respect to weight and thickness required for equivalent protection. I

The acoustical facing layer I 0 may as has been pointed out comprise any of the known acoustical materials now upon the market, such as the plastic acoustical materials sold under the trade names Berry-Gel and Sabinite Plaster," or it may comprise any of the preformed acoustical tiles such as Acoustone, Sabinite, Acousti- Celotex and Calicel Acoustical Tile. When either a plastic acoustical material or a preformed acoustical material is employed a satisfactory bond with the flreproofing slab may be obtained by permitting the plastic vermiculite and mineral plastic binder to set from its plastic state in contact with a layer of the acoustical material either in the plastic or preformed condition.

Having thus described the invention, what is claimed is:

1. A preformed composite slab suitable for use as a fireprooflng and acoustical slab comprising a slab of non-combustible material capable of resisting high temperature without disintegration having a body portion comprising expanded vermiculite and a ypsum plaster binder in proportions of from two to four parts by weight of binder to one part byweight of expanded vermiculite and an acoustical facing layer securely bonded to one surface thereof and of less thickness than said body portion.

2. A preformed composite slab suitable for use as a fireproofing and acoustical slab comprising a slab of non-combustible material capable of resisting high temperature without disintegration having a body portion comprising expanded vermiculite and a gypsum plaster binder in proportions of from two to four parts by weight of binder to one part by weight of expanded vermiculite and an acoustical facing layer securely bonded to one surface thereof and of less thickness than said body portion, said body portion being approxi'mately two inches in thickness and said acoustical layer being approximately three-quarters of ninch in thickness. '1 Q PAULWJENKINSW;

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