T
HE factory floor bears a close relation to employees; and in the chemical industries it bears a more definite relation to the materials in process, either raw, intermediate, or finished, than any other part of the factory building. Floors are subject to severe wear and tear from movements of men and materials. In many instances such forces of disintegration are supplemented by those of spillage and consequent cleaning, moisture, heat, cold, and vibration. Any floor must be adequate, as an integral part of the building structure, to bear the loads placed upon and moved about upon it, but in those industries which handle chemical materials or involve chemical processes, the problem is complicated by conditions not encountered in purely mechanical operations. The industrial enginem or architect who has the responsibility of choosing the type of floor or of floor surface best suited to the factory building and its purpose has a t his disp o d little specific information. He must be guided largely by the past experience of those who have carried on similar operations and have found certain types of floor surfaces suitable or unsnit.able for exposure to the various materials. Ifhe happens to be chemioally minded or to possess more than a layman’s chemical knowledge, he may have at his disposal a few generalizations, such as the solubility of asphaltic materials in organic solvents or the poor resistance of portland cement concrete to oils. The facts remain, howwer, tbat in many chemical industries the plant floor is unsuited to resist the ravages of conbact with the chemical materials handled, and that this condition i? the result of a lack of specific information on the part of those who chose tlie fioor surface. The problem of choosing a suitable flooring material de-
mands tho consideration of scientifically observed past experience, combined with the results of specifically directed research. Of the latter, the authors have been able to find only the most meager record. Probably no agency has scientifically tested flooringmaterials in the way, for instance, that the lining materials for various chemical reaction cbambers have been investigated. To undertake such work would seem well worth the effort. This paper can do little more than state the problem and suggest the need of work to be done. The problem is t o specify for the industry a floor which, a t a reasonable oost for installation and maintenance, will provide resistance to chemical attack, resistance to mechanical and physical deterioration, employee safety and comfort, and long service with a minimum of interruption for repair and replacement. For our purpose here, the materials used in chemical industries may be roughly divided into scids, alkalies, and organic solvents. When considering their effect on the floor, we must differentiate between strong mineral acids, weak mineral acid?, and organic acids, either wet or dry. Alkalies may be strongly caustic, eit,her dry or in solution, or of any degree of lesser strength. From the flooring standpoint, organic solvents should include those oils and petroleum fractions and the oily coal-tar materials which exert solvent action on some types of flooring. The above classification leaves out several materials-among them, milk, sugar, and beepwhich demand consideration. Then, too, water and water vapor, heat and cold, may further complicate the problem. The floor that is to be exposed to one or several of the above agents will be expected t o offer, in addition to resistance to attack, a first cost which is not prohibitive and to lend 283
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itself to quick and inexpensive repair. Safety, which necessitates an even but nonslip surface, will be furthered by a floor which is resilient to the foot, warm, and quiet. The floor should be capable of withstanding the required amount of trucking and traffic without cracking or rolling and should be dust-free and easy to clean. The National Safety Council (IO) lists the following five requirements for a safe and satisfactory floor. 1. It should be smooth and free from nails, bolts, and other projections, and from holes and splinters. 2. It should be dry, low in heat conductivity, durable, and easily cleaned. 3. The floor and foundation should be constructed strongly enough to bear at least four times the standing load and six timesuthe moving load that may be placed upon it: 4. It should be as nearly noiseless as possible. A noisy floor may wear well, but the noise of feet, trucking, and machinery may have an irritating effect on the worker. 5. It should not be slippery or made of material which will become slippery after wear.
To provide such a floor, a wide variety of flooring materials is available. They may be classified in five groups as follows: earth, wood (planks or blocks), metal (steel plates or gratings), composition (cement concretes, asphalt mastic or blocks, magnesite), and stone and ceramic (stone blocks, brick, ceramic tile). The decorative flooring materials, including linoleum, cork, rubber, terrazzo, and mosaic, are usually considered unsuitable for industrial use and will not be discussed here.
Earth Floors Earth, as a flooring material, has little place in the chemical industry. It has some good characteristics-among them, low first cost, ease of maintenance, comfortable walking surface, and, when dry, safety. Its undesirable characteristics make it particularly unsuited for use in the chemical industries. Earth is highly absorbent toward any liquid spilled on it, and, when spilling occurs, the material cannot be removed without taking away part of the floor. If the spilled material is allowed to remain in the earth, undesirable conditions result. When earth is wet, it becomes mud. This drawback and the fact that heavy trucking is almost impossible on an earth floor constitute disadvantages for nearly any industry. Foundries are among the few work places where earth floors have enough good points to outweight the disadvantages.
Wood Floors Wood floors outnumber all other types found in industries, and for a long time to come they will probably be considered the all-round choice for general manufacturing. A wood floor of sufficient weight to withstand heavy trucking and to furnish a foundation for machinery cannot be considered a low-cost proposition. If such a floor is to be laid over a base resting directly on the ground, precautions must be taken to guard against moisture. Failure to do so usually means the early loss of the floor through rotting and buckling. Moistureproofing may be accomplished by laying floors over a foundation of crushed stone and tar, or over concrete coated with a mixture of sand and tar. I n order to withstand heavy trucking, the Western Electric Company (IS) found it necessary to use maple planks of a thickness up to 17/8 inches in the aisles of their factory. Lighter weight planks failed as a result of breaking and splintering. Moreover, it was found necessary to lay the planks lengthwise in the aisles, since heavy trucks rolled transverse to the wood planks caused a rough and uneven condition.
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Since wood planks will not stand up under moisture from beneath, they will obviously not withstand it from above. Therefore, any process which involves a degree of wetness either through spillage, condensation, or simply constant high humidity may be expected to cause damage to an unprotected floor of wood planking. I n addition, unprotected woods have little or no resistance to either acids, alkalies, or oils, They absorb liquids which soften the fibers, and disintegration and roughness soon follow. There is little use in using a wood-plank floor under such conditions with the intent of replacing damaged planks from time to time. This procedure is difficult and interrupts processes; the new unworn planks are generally higher than the surrounding areas whose surfaces have been worn away through use. From a safety standpoint few floors are as hazardous as a wood-plank floor which has been maltreated or where original conditions were unsuitable. However, wood floors can frequently be covered with plastic material, and such procedure will be discussed later. Another type of wood floor which enjoys a successful reputation in many industries, including some chemical processes, is the creosoted wood-block floor. The blocks generally consist of red wood or of hard longleaf pine stock laid with the grain vertical. The thickness of the blocks is usually from 2 to 3 inches, depending on the amount of traffic to which the floor will be subjected. The blocks are impregnated with creosote under a pressure of from 8 to 12 pounds, and since the higher pressure produces a block of much greater resistance to absorption (6),this type of impregnation should be insisted upon when the floor is to be subjected to contact with liquids or moisture. A creosoted wood-block floor will usually give good service under heavy trucking and can be much more easily repaired than a floor of wood plank. Damaged sections can be lifted and replaced, or in some instances the blocks may be reversed, end for end, to give a new surface. It is less easy to fasten machinery to a wood-block floor than to one of planks, and sometimes this difficulty can be surmounted only by providing a platform of some other material on which machines may rest. The method of laying the creosoted wood blocks on the foundation flooring has been subjected to much investigation. If the blocks are not thoroughly footed, they are subject to failure by buckling, looseness, cupping, and unevenness (4). Creosoted wood-block floors seldom fail from decay. If properly manufactured and treated and properly installed, the blocks wear indefinitely, and when the floors do eventually fail, it should be from wear alone. Occasionally, however, they do not give the long and satisfactory service which is expected of them. When premature failure occurs, it is usually either from undue shrinkage of the blocks, causing them to become loose, or from their expansion, causing the floor to buckle. Floors subjected to considerable humidity or moisture frequently fail for the latter reason. I n the first case, when the blocks become loose, foreign matter soon sifts between and under them and makes the floor rough and uneven. The blocks than have a tendency to travel with the traffic and, as they get out of level, soon broom a t the ends and break. This condition also permits water to seep under the floor, which aids materially in the second usual cause of failure-that is, expansion. Expansion a t this stage will cause the floor to buckle because the joints are full of incompressible dirt and foreign matter. Expansion joints about an inch wide, should always be placed along walls and around columns, machine bases, etc. Creosoted blocks have been known to expand 5 per cent of their volume in passing from the dry to the saturated state. Since expansion joints alone cannot be expected to take care of this extreme condition, it is obviously necessary that each block be surrounded by a material which in itself can act as an
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INDUSTRIAL AND ENGINEERING CHEMISTRY
expansion joint. This material should be compressible and waterproof. A bituminous or asphalt material is generally used for the purpose. The best practice calls for a smooth concrete foundation for the creosoted wood blocks. If the blocks are to be laid directly on the concrete, which in some instances is desirable, the foundation must be exceptionally level and free from flaws, and should be first coated with a thin layer of coaltar pitch which is allowed to harden before the blocks are placed on it. Various materials are sometimes used to provide a cushion underneath the blocks and to compensate for their unevenness. Sand alone should be avoided for this purpose since it is likely to shift and cause unevenness in time. The best practice calls for a half-inch layer of one part of cement and four parts of sand on which water is sprinkled immediately before the wood blocks are set in place. This mortar will harden and provide a firm base for the support of the blocks. The wood blocks should be separated from one another by a definite space filled with asphalt or coal-tar pitch. This is accomplished by pouring the molten bituminous material over the tops of the wood blocks, working it into the interstices with a squeegee, and finishing off with a hot iron. A thin film of the bituminous material remains on the surface of the blocks and thereafter provides a surface which is to a considerable extent protected against liquids other than oil. It is considered poor practice to fill the spaces between the blocks with sand or other hard material which is incompressible and, in addition, will work down underneath the blocks and eventually cause them to rock. Until the bituminous material remaining on the surface has had time to dry, which in some instances takes 2 or 3 weeks, the surface of the floor may be covered with sand. This will mix with the plastic material and work into the surface of the blocks, further strengthening the surface and making it impervious to most liquids. From a chemical standpoint a creosoted wood-block floor prepared as described above can be expected to give good service in many locations. It should withstand moderate amounts of moisture, acid, and alkali. Oils and organic solvents will, however, quickly exert a solvent effect on the bituminous filler and coating and give trouble. From a safety standpoint tho floor should be a success because it will be nonslippery, fairly smooth, warm and comfortable to walk upon, and not subject to cracking or splintering.
Metal Floors Metal floors have inherent objectionable c h a r a c t e r i s t i c s which have usually confined their use to places where any other type of floor would fail from mechanical causes. Steel plates or gratings are expensive and extremely hard on the legs and feet; they make an unpleasant standing or walking surface, are very hot or cold depending on weather conditions, and are conductors of electricity. They have, howerer,
285
certain characteristics which render them valuable for specialized purposes. They are almost indestructible, are easy to clean, and, by means of a raised patterned surface, can be made practically nonslip. Trucking over a nonslip pattern is somewhat difficult, and for this reason smooth steel plates are often used in aisles. These may be very slippery when they become wet or oily. Steel floors and gratings find their most appropriate use on stairways, platforms, raised walkways, and elevator landings. They should hardly be considered a possible material for the whole floor except under unusual conditions.
Cement Compositions
Next to wood, the most common types in use today are composition floors. This classification includes cement and cement concrete, asphalt mastic, asphalt blocks, magnesite and other patented compositions which are usually similar to one of these types. Cement or cement concrete floors seem to be the conventional floors selected whenever anyone wishes to avoid wood flooring. There are few floor surfaces with less to recommend them than this type, unless the surface is so treated or covered as to take on entirely new characteristics. A cement concrete floor has a comparatively low first cost and is nonslippery if kept clean. It is also fairly easy to clean. The advantages seem to end at this point, except for a few isolated cases where engineers have apparently produced a concrete floor which stands heavy wear without cracking, pocketing, or dusting. As a rule, cement concrete should be regarded simply as the foundation on which to place a surfacing material suitable to a specific purpose. Cement concrete has been made in thousands of combinations of ingredients for floors. It usually consists of a rock aggregate, which may be of various size or composition, of a filler which is usually sand, and a cementing medium, which may be portland cement, pozzuolanic cement, slag cement, alumina cement. or other less common types. A cement floor has certain characteristics which are inescapable because of the fundamental struoture of the material. Being an artificial rock, it is cold and hard, and constitutes a surface on which it is unpleasant to stand or walk for any length of time. Sooner or later it will break under moderate or heavy trucking; the break will take the form either of cracks, pits or gouges, which make the floor uneven and c o n s t i t u t e stumbling hazards to interfere with truck operation. When a cement floor has reached this state, it is almost impossible to patch it with more cement. It is then necessary either to relay the entire floor or to patch it with some of the plastic compounds developed for the purpose. In so doing we then have a floor of two or more different materials which is undesirable. A cement floor resists water well b u t n o t contact with Two ADJOINING TYPESOF FLOORING OF DIFacids, alkalies, or oils. The FERENT HEIGHTSRESULTIN BROKEN CONwide variety of minerals incorCRETE AND STEELPLATE
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INDUSTRIAL AND ENGINEERING CHEMISTRY
porated in ordinary concrete generally includes one or more substances which are acid soluble, and only a mixture specifically designed to be acid resistive will stand up in the acidusing industries. Alkalies are hard on cement because they either dissolve or combine with silicates, and concrete always contains silicate material. Oil penetrates the pores of concrete by capillary attraction and causes it to disintegrate. Cement will sometimes fail as a result of extreme heat or cold or of vibration. Thus, a concrete floor without a surface of some other material is comparable to any other structural material whose surface has not been properly finished and protected. Numerous materials are adapted to coating concrete which will guard against nearly all of the threatened forces of disintegration, but no one coating will guard against all. A cement and sand finish over a concrete floor, giving to the floor a monolithic finish, has the advantage of a perfect bond to the foundation concrete but eliminates none of the objections. By painting a smooth cement surface, we overcome the dusting proclivity, and paints which are moderately resistant to weak acids are obtainable. Powdered gypsum dusted onto the cement surface while it is still moist will harden the surface and produce resistance to weak acids and alkalies and also reduce dustiness. Sodium silicate with the ratio of 3.3 molecules of silica to 1 of soda (6) has been used with success as a surface hardener to render the cement waterproof and to prevent dusting. The cement surface may be hardened against abrasion by incorporating in it a t the surface iron or copper filings, silicon carbide, or Alundum. However, in making tests of various hardening agents for cement surfaces, the Western Electric Company ( I S ) finally concluded that a wearing surface of cement, sand, and granite chips stood up better than any of the various hardening ingredients which they subjected to actual comparative tests. More specific hardening treatments for concrete surfaces are given by Foster (6) with full directions for their use. One is the sodium silicate treatment referred to; the other chemical hardening agents described are zinc and magnesium fluosilicates, aluminum sulfate, and zinc sulfate. Occasionally the susceptibility of a cement floor to chemical attack can be reduced by choosing a cementing medium other than conventional portland cement. For instance, sulfate waters attack portland cement (8). Resistance to this attack is improved by aging, increasing density, and lowering the water permeability of the cement mixture. I n place of portland cement, a high-alumina cement gives apparent immunity to this type of attack; blast furnace slag cement and pozzuolanic cements give better resistance than does portland. Portland cement is attacked by sewage owing to the hydrogen sulfide which apparently yields sulfurous and sulfuric acids (1). Because of its greater free lime content, portland cement is less resistant than alumina, supersulfated, and slagportland cement. This principle can be extended to plants handling sulfurous and sulfuric acids. Even solutions of neutral salts have been found to attack cement (7’). Sodium chloride and potassium chloride in two normal and in saturated solution were placed in contact with eight different cement compositions. All of the constituents of the cement were attacked except the silica. The chloride and oxychloride of calcium were formed, and much aluminum oxide was dissolved in the sodium hydroxide and potassium hydroxide which were produced by the reaction. Apparently, then, even when cement is given a hardening treatment, it is still subject to a multiplicity of attacks, both mechanical and chemical. Since cement and cement concrete are undoubtedly valuable structural material, it seems logical that if a concrete floor can be covered with a sufficient
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thickness of a suitable material to prevent the exposure of any of its undesirable characteristics, that should be the aim of the engineering architect. The asphaltic and magnesite materials seem to offer many favorable features.
Asphaltic Compositions The more common plastic materials for floor covering are asphalt mastic and asphalt emulsion. These materials are useful for patching broken concrete and damaged floors of other types, and they have a definite usefulness as coverings for wood floors. They are the logical rivals of creosoted wood blocks as surfacing materials on concrete bases and, unlike creosoted wood blocks which require a firm, level base, can be laid over old and damaged wood flooring, since their flexibility adapts itself to a nonrigid foundation. The asphalt plastics contain a mineral aggregate, cement or gypsum, asphalt, and either water or an organic solvent. The hot mastic asphalt compositions contain an organic solvent to render them fluid enough to work, whereas asphalt emulsion has water in place of solvent and possesses corresponding advantages because of the absence of any fire hazard while the material is being laid. Cost is lowered because the dry materials can be mixed with water obtained on the job. Whether the floor surface is of hot mastic asphalt or asphalt emulsion, the final result is much the same, but the fire hazard during application from the hot mastic type is serious enough to render the emulsion type definitely more desirable. The National Fire Protective Association (9) reported the occurrence of several serious fires when hot mastic asphalt floors were being laid: “The material, which comes in sealed drums, contains asphalt, asbestos, sand, and pigments intermixed with naphtha. It ignited, and then the floor itself burned rapidly. Another fire occurred while a similar floor was being laid, the vapors being ignited by a spark from a chisel on concrete. A high flashpoint solvent to replace naphtha is recommended.” As a consequence, asphalt plastics of the emulsion type will be considered here primarily. The National Safety Council (11) states as follows concerning asphalt emulsion: A more recent adaptation of asphalt to industrial use consists of asphalt emulsion in combination with sand and cement. These ingredients are made into a mortar and laid cold about one-half inch thick. The mortar may be laid by common labor but experienced supervision should be provided. When laid over a wood base, it will carry moderate traffic; with a concrete base it will stand up under heavy trucking. The surface is more resilient under foot than concrete, and trucking is somewhat easier than over hot asphalt mastic. Much has been written about this useful material whose properties are not understood by many prospective purchasers. As with paint, there is a great variety in the quality of the various makes on the market. Some of these are marketed under trade names and some merely as cold mixed asphalt cement. Some who have believed that any kind of asphalt emulsion mixed with cement and sand would produce a perfect floor have been disappointed. Others who have called in representatives of reliable companies and had the installation made according to their directions have found the results quite satisfactory. These few companies, which have made scientific studies of maintenance problems, do not offer any blanket prescriptions for flooring without studying the plant and its manufacturing processes, Where concrete floors are to be patched or resurfaced with asphalt emulsion mortar, chipping, roughening, or acid washing are not necessary. The mortar bonds well to concrete, brick, and wood. Another advantage is that it can be tapered down to a feather edge. Most of these products require a priming coat before the patch is applied. The weight of the mortar when dry is approximately four and one-half pounds per square foot which does not seriously decrease the working load limit of the floor. Any material which can be applied cold avoids the obvious hazard of fire and burns from handling hot substances. Asphalt emulsion mortar over wood floors in paint spray
I
MARCH, 1939
INDUSTRIAL AND ENGINEERING CHEMISTRY
booth and motion picture projection rooms is approved by Fire Insurance Underwriters. The high content of sand in the mortar (about 50 per cent) keeps the surface from becoming slippery through wear.
An asphalt floor has certain valuable advantages. It is, or can easily be made, practically acid- and alkaliproof. I t is waterproof in itself, and if extended up the sides of the wall a few inches where the wall joins the floor, there will be no danger of water leaking through to the floor beneath. It provides an excellent wallcing surface from the standpoint of safety and comfort, since it is resilient, warm, quiet, and nonslip. When properly compounded and laid, i t will bear a surprisingly heavy truck without indentation. Older types of asphalt floors are inclined to become soft in hot weather and brittle in cold weather, but i t is understood that these dimculties have now been largely overcome. One company supplying this type of flooring claims that its product will withstand heat up to 1,700" F. and trucking loads of 10 tons on 4-inch treads. This product consists of an aggregate of volcanic rock, asphalt binder, and cement setting powder. These three materials are mixed on the job with water to form a workable emulsion. The old floor or the foundat.ion Boor is prepared by sealing with a membrane, if necessary, and an asphalt binder is first applied. After the laying of the asphalt emulsion in a half-inch layer, the floor will dry sufficientlyto be used in 24 hours. In 48 hours it is completely dry and forms E surface which is described as nondusty, nonslippery wet or dry, fire resistant, practically fireproof, nonconducting of electricity, waterproof, and resistant to alkalies and all acids, including chromic acid. The manufacturer, however, warns that oil, fats, grease, sirup, and solvent coming in condact with an applied flooring of this type tend to disintegrate it. Cold storage rooms, fish houses, refrigerating rooms, killing room floors, or wet Boors in packing plants, sausage plants, canneries, laundries, dairies, etc., are not considered suitable for this type of flooring unless certain special conditions and precautions are first followed.
287
s p h a l t and gypsum. Still greater acidproof characteristics can be obtained by placing a top coat of a n d and asphalt on the surface of the regular asphalt-emulsion mix. The properties of nonresistance to oils, solvents, and milk still remain. Asphalt blocks make a floor which is chemically similar to asphalt mastic. Since these blocks are fabricated under pressure, they last considerably better under standing and rolling loads than the mastic material. The United States Navy (18) in 1920 published some interesting observations on the use of asphalt blocks in storage battery plants and other locations where the floor was to be subjected to both strong acid and heavy standing and rolling loads: The main consideration, that the floor shall be and remain inert to chwnical action, is filled to an admirable degree by a special acid-resisting asphalt block. The asphalt blocks selected are 8 x 4 inches in surface dimensions and admit of repairs by simply lifting and reversing the injured block or blocks. The manufacturing pressure is 4 tons pcr square inch, which insures a product of such density that standing loads have no effect. The asphalt blocks are laid upon a.z/rinob, 1:4 cement mortar bed. Ordinarily, no joining matcnal other than sand is r e quiied as they Soon weld under traffic to a continuous surface. This action is hastened by the fine sand which ip spread over the surfaceof the floor and allowed to work into the joints.
It is stated that in locations where traffic is insufficient to produce a sealing action, an asphaltic filler or asphalt wash can be applied on the surface, whence it penetrates into the joints and seals them. The writer continues: "The case of the galvanizing plant, copper shop, and the floors around the plate-pickling tanks is fairly similar t.o the above, but with one important exception. The acid and alkali baths introduce the same chemical problems as before, hut the presence of heat in the metal baths and the weight of the plates handled make i t advisable to pave the floor immediately around the metal bath tank with a vitrified brick of selectcd attributes, set in asphalt, and the rest of the door as described above." Since this was written more than 18 years ago and i t is known that asphalt floors have been made considerably more heat resistant since that time, it may be that the objection no longer applies. The same writer (18) gives some interesting cost figures which may or may not be of value except for comparative purposes. The cost of l'/Anch compressed asphalt blocks used in the battery building a t the Philadelphia Navy Yard amounted to $2.90 per square yard, of which OI.35 represented the cost of the asphalt blocks, $0.35 the freight and the laying, $1.00 the concrete base and mortar bed, and $0.20 the asphaltic seal for the joints. This was hy far the cheapest flour on the market a t the time; by comparison with then recent figures, the first cost was less than that of either brick or wood blocks, and maintenance expense negligible.
Magnesite Compositions
CONCRETE F ~ o o aPITTED BY ACIDDRIP FaoM PICKLINQ TANKS
A similar product made by another company substitutes traprock for volcanic rock and gypsum for cement. This material is also laid over a waterproof membrane after an asphaltic binder is first applied. The use of traprock in place of volcanic rock increases the acid-resistant properties to some extent. This product yields a specially hard surface when a finishing coat is applied consisting of a mixture of
Magnesite is another plastic material, not usually regarded as a n industrial flooring, which seems to have certain desirable characteristics warranting consideration. Magnesite is a cementing material made by first calcining magnesium carbonate and then causing the resulting magnesium oxide to interact with magnesium chloride, yielding magnesium oxychloride. The final reaction takes place in water solution. The resultant material may be mixed with sawdust, wood flour, or various fillers, such as silica, asbestos, or kieselguhr, to give floorings of various characteristics. These mixtures are suriacing materials onIy and have to be laid over a foundation of either cement or wood in a manner similar to the asphaltic compositions.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
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IMMUNITY OF FLOORS FROM WEARING BY TABLEI. RELATIVE Dow ABRASION TEST(4) Oxychloride heavy-duty flooring (av. 8 prepared samples) 414 233 Hard white porcelain tile (Mosaic) 164 Common red tile (hard, unglazed) Inlaid linoleum (best grade) 147 Inlaid linoleum (medium grade) 113 Semihard oxychloride flooring (av. 4 submitted samples) 103 Hard maple flooring 100 White oak fiooring 88 Asphalt mastic 73 Hard yellow pine flooring 63 Oxychloride composition flooring (resilient type) : Av. 7 submitted samples 51 Av. 10 prepared samples 47 43 Portland cement (1 : 1 mix) White marble slab 28 Alberene stone 16 White pine flooring 16 14 Portland cement (1: 2 mix) 11 Portland cement (1 : 3 mix) Printed linoleums 1-10
Magnesite develops higher compression and tensile strength than portland cement (2), will bind many times greater amounts of inert material, but has not been used for massive construction purposes because of its greater cost. Magnesite corrodes some metals and therefore should not be allowed to
come in contact with pipes, structural metal, etc. The metal may be protected from such contact by bituminous paint. Magnesite floors should not be laid over damp undersurfaces, and the same waterproofing precautions may be taken as with asphaltic compositions. By choosing the proper aggregate, a hard-wearing abrasionresisting floor surface can be made, suitable for use in factories. In order to retain resiliency, the floor may be laid in two layers, with the more resilient layer containing a higher percentage of sawdust or wood floor underneath. The Dow Chemical Company (3) tested various flooring surfaces for their abrasion-resisting properties with results shown in Table I. The magnesite composition (referred to as oxychloride) outstripped all other materials by a wide margin in abrasion-resisting properties. Numerous references in the literature state that magnesite compounds do not wear well. It is believed that these references must mean the resilient types which, in Table I, do show a low index but nevertheless indicate better performance than portland cement. Magnesite compositions are not particularly resistant to strong acids but compare favorably with portland cement mixtures in their resistance to gasoline, milk, beer, and sirup. Oil, which has a severe deteriorating effect on cement is said (2) actually to benefit magnesite floors. No information has been found on its resistance to attack by alkalies but from the chemical make-up of cement, the resistance would probably be lower than that of portland cement.
TABLE11. CHARACTERISTICS OF FLOOR SURFACES'
Floor Surface
Initial Cost
Ease and cost of Repair
Safety with ResistResistReferance ance ence Ease Ease to Resist- t o Resist- ResistResiliResistto of of Trucking ance Oil and ance ance ency ance Slipperi- Clean- Truckand to Organic to to Cleanli- Quiet- (Foot to ness Ease) Warmth Heat ing ing Abrasion Water Liquids Alkalies Acids ness ness
~~
Earth
Verylow C h e a p : Good easy
W o o d planks
Moderate
M o d e r - Fair ate but troublesome M o d e r - Good ate
Creosoted M o d e r wood ate blocks Steelplates High E a s y; a n d seldom gratings necessary C e m e n t Low Very difconcrete ficult C e m e n t M o d e r - Very difw i t h ate ficult harde n e d surf ace Asphalt Moder- E a s y : mastic ate moderatecost Asphalt Moder- E a s y : blocks ate moderate cost Magnesite High Doubtful S t o n e F a i r l y Moderblocks high ate Brick Moder- Moderate ate C e r a m i c High Difficult: tile expensive 0
V e r y V e r y V e r y None diffidiffilow cult cult DiffiGood Fair Poor cult
...
...
.,.
None
Good Good Poor
Poor
Poor
Poor
Fair
Good Good Good Poor
Poor
Goad
Difficult
Good
Fair
Fair
Fair
Good Good Good
Poor
Variable
Good
V a r i - V e r y Good Good Good able good
Poor
Good
Poor
Poor
Poor
Good
Good
Good
Good
Poor
Fair
Poor
Poor
Poor
Dusty Poor
Poor
Poor
Poor
Good
Good
Good
Fair
Fair
Poor
Poor
Poor
Good
Poor
Poor
Poor
Poor
Good
Fair
Fair
Good
Good Poor
Good
Good Good
Good Good Good
Fair
Good
Fair
Good
Good
Good
Good
Good Good
Good Good Good
Fair
Fair
Good
Good
Good Good
Fair
V a r i - Good able Fair Good Poor
Good
Fair
Fair
Poor
V a r i - Good Good Doubtful Fair Good able V a r i - Good Good Good Poor Fair Fair able Fair Good Poor Good Fair V a r i - Fair able Good Good Poor Good V e r y Good Poor good
The data are in moat instances a compendium of opinion only.
Good
Poor
Poor
Poor
Good
Fair
Poor
Poor
Good
Poor
Poor
Poor
Good
They are not scientifically tested and mar prove erroneous
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INDUSTRIAL AND ENGINEERING CHEMISTRY
Magnesite compositions are not actually fireproof but they will not conduct fire. When subjected to burning heat they disintegrate to a powder, but will not flame or smoulder. From a safety standpoint, a magnesite floor can be either slippery or nonslippery, depending on the surface finish and the possible applications of wax, etc. Decorative magnesite floors in office buildings, etc., are often waxed and become quite slippery, but the industrial type floor generally provides a good and safe walking surface.
Stone and Ceramic Blocks Stone blocks, usually granite, are durable materials and will resist most chemical agents well. Needless to say, they form an extremely harsh and unpleasant walking surface, are subject to all the objections of steel plate in this regard, and should be considered as foundation material rather than surfacing. Bricks are especially useful because they are heat resisting and can easily be torn up to allow for changes in the location of machinery, etc. They are acid resistant and comparatively inert to oils and alkalies, although their porous nature makes them likely to absorb liquid materials spilled upon them. Ceramic tile, usually glazed, is used in a few specialized locations, such as dairies, where extreme cleanliness is important. Moreover, glazed ceramic tile is one of the few materials which will withstand chemical attack by milk.
Conclusions Table I1 gives a summary of the discussion of the various types. The opinions should not be accepted as rigid statements of fact, for exceptions are numerous and some one objectionable characteristic of a certain type of floor can often be overcome by special treatment or compounding. It is apparent that there is no universal flooring material. Different departments of the same plant will probably require
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different materials in order to obtain a flooring which will produce a good performance. The need for real scientific investigation is again emphasized. It seems reasonable to believe a cooperative program between the manufacturers of flooring materials and the chemical industries could make possible great progress toward the solution of the flooring problem. The fact that. most large flooring material concerns deal in one type only is a hindrance to this goal, since advertising and sales pressure have never been consistent with truly scientific investigation. I n considering a flooring material, safety features should rate high among the various criteria. No floor, no matter how good a trucking surface it may be, no matter how resistive to acid, alkali, and oil, no matter how long wearing, will be satisfactory unless it provides a nonslippery even walkway and is reasonably comfortable. Floors which fail in the safety requirements have to be resurfaced sooner or later or spread with mats, gratings, or plastic compounds in which abrasives are set. Such a necessity is an admission that the original floor failed in one of its most important requirements-that is, to provide a surface fit and safe to walk on.
Literature Cited (1) Antill, Commonwealth Engr., 24, 395 (1937). (2) Comber, A. W., “Composition Flooring and Floor-laying,” Philadelphia, J. B. Lippincott Co., 1936. (3) Dow Chemical Co., “Plastic Magnesia Cements,” 1927. (4) Ericson, L. J., Eng. and Contr., 49, No. 13, 64 (1918). (5) Ferguson, H. K., and Magee, B. R., Iron Age, 115, 1127 (1925). (6) Foster, J. E., Natl. Engr., 34, 509 (1930). (7) Hundeshagen, F., Zement, 26, 103 (1937). (8) Lea, Surveyor, 89, 669 (1936). (9) Natl. Fire Protective Quart., Jan., 1926, 293. (10) Natl. Safety Council, Safe Practises Pamphlet 11 (1924). (11) Natl. Safety News, March, 1938, 53. (12) Rinker, H. S., Eng. News-Record, 85, 54 (1920). (13) Spurling, 0. C., Ibid., 109, 191 (1932). R E C E I V ~August D 11, 1938. Presented before the Division of Industrial and Engineering Chemistry at the 96th Meeting of the American Chemical Society, Milwaukee, Wis., September 5 to 9, 1938.
Adsorption of Copper Ions by Chlorinated Copperas Floc
P
REVIOUS papers have been concerned with the removal of dissolved copper salts from water supplies in the usual course of chemical coagulation by means of aluminum sulfate ( I ) , ferric ammonium sulfate ( 2 ) , and sodium aluminate (3). I n continuing this work i t was of interest to examine the effect of chlorinated copperas (FeClSOJ as the coagulant in the removal of dissolved copper salts since this material is used in water treatment plants. The experimental details were the same as given in the previous papers. The chlorinated copperas solution was made 0.01 M in terms of ferrous sulfate, and then chlorinated to complete oxidation. The essential information follows: Test KO. 1
12 21 26 27
2s
81 82
--Buffered Fe soln.
Water-Cu s o h .
P.p.m.
P.p.m.
22 18 18
1.9 16.4 16.4 16.4 14.3 25.0 19.6 18.2
1s
160 138 21.6 104
-Filtered pH
WaterCu removed
% 6.9
6.7 6.3
6.0 6.7 5.5 4.6
c3.s
100 100
82 82 100 100 88
100
C. J. BROCKMAN
University of Georgia, Athens, Georgia
These data indicate that above a pH of 3.8 in these phosphate buffer solutions, there is a complete removal of considerable concentrations of copper ions, provided the proper quantity of coagulant is used. The formation of the floc does not remove all of the iron salt from the solution a t the lower pH values, owing to the fact that chlorides do not form as insoluble basic salts with iron and aluminum as do the sulfates, and also that iron salts form very stable complexes with phosphate ions.
Literature Cited (1) Brockman, C. J., IND.Eng. CHEM.,25, 1402 (1933). (2) Ibid., 26, 924 (1934). (3) Ibid., 27, 217 (1935). R E C ~ I V BSeptember ~D 30, 1938. Presented before the Division of Water, Sewage, and Sanitation Chemistry at the 93rd Meeting of the American Chemical Society, Chapel Hill N. C., April 12 to 15, 1937.
