US 3298290 A
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E. R- DU FRESNE Filed May 24, 1965 Q S n Ra n m m w N f u MD M J R% e u w N Jan. 17, 1967 METHOD AND MEANS FOR ICE CONTROL PIC-3.3
3,298,290 METHOD AND MEANS FOR ICE CONTRGL Eugene R. Du Fresne, Chicago, lllL, assignor to Renslow D. Sherer Filed May 24, 1965, Ser. No. 465,232 4 Claims. (Cl. 94--4-) This invention relates to a method and means for controlling and removing snow and ice, and it more particularly relates to the removal of ice and snow from places where it is prone to create severe inconvenience and hazardous conditions such as on streets, sidewalks, and driveways.
This application is a continuation-in-part of applicants copendin-g application Serial No. 101,202, filed April 6, 1961, and entitled, Method and Means for Ice Control, now abandoned.
At present, there are two basically dififerent methods which may be provided for controlling the conditions of streets and the like. The first of these methods comprises the heating of the surfaces, for example, by means of heating means embedded therein. The second method includes the spreading of water soluble substances such as salt onto the surface of the snow or ice, the salt lowering the melting point of the snow or ice, thereby providing for easy removal.
The heating of the streets or sidewalks as by means of inlaid heating devices has the extreme disadvantage of poor elficiency. The cost of electricity, steam, or chemical energy is high in view of the relatively great amount of heat needed to theoretically melt and evaporate one gram of water. This cost becomes prohibitive in almost all cases when the large amounts of energy wasted by dissipation into the surrounding atmosphere is considered.
The use of salt is theoretically much more practical for the intended purposes. Since the principle of its use involves lowering of the melting point of the ice or snow, there is no need for high energy or heat input, the necessary heat being effectively drawn from the surrounding atmosphere. The salt or like materials are also desirable since they melt the ice at a relatively fast rate, a characteristic which is obviously important.
The use of salt or similar products for control and removal of the ice or snow has, however, not lived up to its apparent potential. When a householder scatters salt or the like on newly fallen snow, the grains of salt rapidly melt small holes for themselves and fall through the snow. At the bottom, the salt melts enough snow to produce a rich brine that eventually flows away and is lost. Ordinarily, the remaining snow has enough mechanical strength to hold itself arched over other portions of salt and brine so that it has no chance to be attacked. To compensate for this, it is the practice of a householder to employ a large excess of salt, this procedure serving as much to batter down the snow as to melt it.
The efficiency of salt is somewhat greater when it is used to attack ice or packed snow. In this case, better contact is made with the scattered salt; however, the brine which tends to drain away is still quite rich and represents a considerable waste. In addition, because the brine is concentrated, it tends to damage regions surrounding the streets, sidewalks or driveways either by effecting the fertility of soil or by permitting rapid corrosion of adjacent metallic objects.
A less obvious cause of the inefiiciency of present methods of employing salt is the time at which it is ordinarily used. The heavy snowfalls in the United States tend to occur when a warm moist air mass is forced upwardly by an incursion of a polar Canadian air mass. Thus, the snow will fall during relatively warm weather, which is 3,298,299 Patented Jan. 17, 1967 immediately followed by a cold snap. Since a householder tends to scatter salt after the fall of the snow rather than during a storm itself, the salt is thus provided when the snow or ice is at its lowest temperature. This thus increases the inefiiciency of the salt, since it would naturally be more effective if combined with the snow or ice at a higher temperature.
It is therefore an object of this ivention to provide a method and means for controlling and removing snow and ice, the presence of which is prone to create severe inconvenience and hazardous conditions.
It is a further object of this invention to provide a method and means for controlling and removing ice and snow which is highly efiicient when combined with present heating or salt removal techniques.
It is a more specific object of this invention to provide a method and means for controlling and removing ice and snow which utilizes to a substantial extent a removal capacity available with such materials as salt.
These and other objects of this invention will appear hereinafter and for purposes of illustration, but not of limitation, specific embodiments of this invention are shown in the accompanying drawings, in which:
FIGURE 1 is a detailed sectional view of a sidewalk, street, driveway, or similar surface provided with ice and snow removal material in accordance with this invention;
FIGURE 2 is a detailed top plan view of a surface of the type shown in FIGURE 1;
FIGURE 3 is a detailed cross-sectional view of an alternative means of providing the characteristics of this invention;
FIGURE 4 is a cross-sectional view illustration of a specific embodiment characterizing the concepts of this invention;
FIGURE 5 is a detailed top plan view of an alternative means of providing the characteristics of this invention;
FIGURE 6 is a detailed sectional view of the alternative embodiment of FIGURE 5; and,
FIGURE 7 is an illustration of a form of this invention wherein a flexible unit is provided which is adapted for removal and storage when not in use.
The process and apparatus of this invention may be generally described as a system wherein there is provided a plurality of independently situated cavities within the surfaces to be adapted for removal of snow and ice. The cavities are provided with a chemical substance which is characterized by the property of lowering the melting point of ice and snow when brought into contact there with, salt being a prime example of such a substance.
The invention may be more readily understood when considering the drawings which illustrate in FIGURES 1 and 2 a pavement construction 10 which may be a street, sidewalk or driveway upon which snow and ice are likely to form. Cavities, depressions, or cells 12 are provided within the pavement construction 10. The cells are independently situated and have fluid tight walls 14 and a closed bottom 15 and an open top 17. Located within the cells 12 is a substance 16 which is characterized by the property of lowering the melting point of snow and ice when they are brought into contact with the substance 16. The substance 16 will be normally solid, and common salt ordinarily used for melting snow and ice is the most obvious example thereof.
The construction of FIGURES l and 2 represents the incorporation of the invention in a manner provided in situ with respect to the pavement. As shown in FIGURE 3, it is not necessary that this be done, for a cellular body 18 having independent cells 20 with walls 22 may be associated with the pavement to provide the characteristics of this invention. In this type of arrangement, the cel lular body 18 may be secured to the pavement, formed J integrally therewith,'or simply be portably applied thereto at desired intervals.
FIGURE 4 depicts a desired construction of the pavement from a large scale standpoint. As will be apparent from a later discussion, in order for this invention to be practicable, it is necessary that adequate drainage be provided. This may be simply accomplished by elevating portions of the pavement construction It) as at 24 with respect to the remaining portions of the pavement. It will be apparent that an elevation at any point of the pavement, including at one side of the pavement, which will provide adequate drainage without unduly sacrificing a smooth surface, will be suitable.
A further specific embodiment of this invention is shown in FIGURES and 6. The construction 26 shown therein is similar to that shown in FIGURE 3 in that it is provided with cells 28 closed at the bottom and open at the top and an upstanding wall 30. This embodiment is distinct, however, in that it provides a unique means for draining of the melted ice and snow. Thus, there is pro vined an orifice 32 in the portions of the construction 26 which join the walls of the respective cells. It will be apparent that as the melted ice and snow build up within the cells 28, it will overflow and drain through the orifice 32 and the space 34 beneath the construction 26. In order to supply additional channels for drainage beneath the construction 26, it may be desirable to corrugate the base 36 of the cells 28 or, the pavement upon which the construction 26 rests may be suitably channelled; however, in most cases, the spaces 34 will provide for adequate drainage.
The material employed to manufacture constructions such as shown in FIGURES 3 and 6 which are not formed in situ with respect to the pavement may be flexible in nature. This will permit ready removal and storage of the constructions, for example, by rolling up of the flexible material in the manner shown at 38 in FIGURE 7.
The operation of the devices of this invention necessitates the provision of amounts of salt or like materials which are capable of melting ice and snow in the cells of the constructions described. When a snowfall occurs, the initial portions of the snow fall into the cavities in the pavement construction. There is immediately melting of the snow and formation of brine due to reaction with the salt or other substance within the cavities. An additional amounts of snow fall into the cavities, the level of brine rises; and eventually a drainage of liquid, carrying along with it freshly fallen snow, commences.
A characteristic of salt and the other materials which are employed within the cavities is that the lower concentrations of the materials with the melted snow or ice will rise to the top of the cavities and drain away. In other words, the heavier concentrated solutions of the substance 16 and the melted ice or snow will occur in the lowermost portions of the cavity. This characteristic of the substances 16 which are employed enables conservation to a substantial degree of the substance 16 within the pavement construction.
It will thus be apparent that there are certain practical limitations on the type of material which is used to charge the cells of this invention. As previously noted, it is necessary that the material be characterized by the property of lowering the melting point of ice and snow, and it is further necessary that less concentrated solutions of the substance with the ice and snow be lighter than more concentrated solutions thereof. Some materials such as sugar are feasible for use insofar as these properties are concerned, but impractical from a cost standpoint. Some organic substances such as glycol and other alcohols are also objectionable from a cost standpoint, and further tend to give solutions lighter than water.
Obvious limitations also exist when considering the structure of the constructions of this invention. The cavities or cells should not be of a size that they would be dangerous for walking, such as for women with spike heels. The cells or cavities should therefore be of a crosssection small enough to prevent entry of such heels or large enough to permit entry without danger of catching within the cells. The cells should be deep enough so that the solution of salt carried away is not too concentrated, which situation would deplete the salt values too rapidly. On the other hand, the cells or cavities should be shallow enough to avoid the presence of too dilute a salt solution in the upper portions of the cells. This latter condition could result in eventual termination of snow melting ability.
Cells defining openings between 1 inch and /8 inch in a horizontal direction, and at least A1 inch deep are contemplated. A depth greater than about 1 /2 inches usually proves impractical for the reasons discussed above. It will be understood, however, that in certain instances, cells smaller or larger in crosssection and shallower or deeper, will be more suitable.
A great deal of discretion is available when considering methods for providing the cellular construction of this invention. Where the cells are to be formed in situ with respect to the pavement, the array of cells may be formed directly in the surface of a conventional pavement construction, for example, by means of pressing into fresh concrete. Alternatively, the cells can be formed by cementing a grid of cell walls to the travelled surface. In addition, the array of cells may be prepared as an independent mat by calendering or molding materials in an appropriate way. Such a mat could be formed by embossing or otherwise fabricating sheet metal, resin reinforced paper, or other sheet material. Further, the cells could be pieced together, for example, by assembling cells or cell walls on a backing sheet.
The types of constructions shown in FIGURES 3 and 6 have a singular advantage since they are not formed in situ in the pavement and are adapted to be portable. In these mat-like cellular constructions, which may be formed of rubber or plastic, there may be a precharging operation which amounts to casting of salt or the like within the cells. The precharged mats can then be rolled up as shown in FIGURE 7, stored when not in use, and then spread over desired areas in anticipation of snow. After a certain period of use, the cells can be easily recharged. It is also contemplated to provide cell walls by means of a grid which is formed independently of the pavement and then placed over the pavement. The bottom of the cells will then be provided by the pavement.
A particularly desirable substance for incorporation into the cells is a mixture of sodium chloride and magnesium chloride hexahydrate, this mixture being solid at room temperature. The substance is formed into a liquid by heating since the magnesium chloride hexahydrate, like many other hydrates, decomposes near the boiling point of water. The product is poured into the cavities and allowed to cool. The product is a fluid solution of the salt in its own water of crystallization which will solidify on cooling or when the water evaporates, which ever comes first. Hence, such salts or combinations thereof with other salts, can be cast directly into the cells or be used as cementing agents for rock salt or the like. A mixture of 25 percent magnesium chloride hexahydrate and percent sodium chloride is an example of a combination which may be introduced into the cells.
A typical method for including salt within the cells of this invention comprises the steps of dry mixing crushed sodium chloride and magnesium chloride hexahydrate, loading the mix into cells at room temperature, heating the assembly to about C. for a brief period and air-cooling the heated assembly to room temperature.
Salt mixtures which are employed for recharging of cells should preferably be crushed to a finer grain size than the rock salt presently used for melting ice and snow. This provides for more even spreading; and hoes, brooms tend to rise.
and fertilizer spreaders and the like are all contemplated as possible devices for recharging.
The efiiciency of operation of this invention is greatly enhanced by certain factors characteristic of the reaction between salt and ice or snow. The amount of salt or other substance needed to melt a given weight of ice or snow is roughly proportional to the number of degrees below freezing at which the ice or snow occurs. Therefore, the fact that the instant procedure is available for melting of the snow immediately as it is falling means that less of a melting substance is needed for removal since the snow is normally, at this time, at a relatively high temperature.
Furthermore, at temperatures below 4 C., normal evacuation forces are reversed, that is, colder solutions This characteristic increases the rate of action of the instant invention in that a diluted volume of brine which has been cooled by yielding up the latent heat of fusion necessary to melt the snow will tend to rise to the top of the devices.
This spent, or nearly spent, element of brine is thus urged upward within the cells of the devices by two forces, namely, thermal evacuation and the aforementioned density separation. Additionally, with the coldest brine spread out at the upper surface, heat exchange with the atmosphere is favored, whereas it would be delayed if the colder solutions tended to sink beneath the surface. This situation results in an extremely unobvious advantage of the instant procedures in that the devices of this invention actually tend to act more rapidly as the rate of snowfall increases and do not tend to saturate. There has been no observation of snow collecting on the Working surfaces, even temporarily, where the surfaces are characterized by the features of this invention.
It will be understood that various modifications may be made in the above disclosed method and means for control and removal of snow and ice, which modifications will provide the characteristics of this invention without departing from the spirit of this invention, particularly as defined in the following claims.
That which is claimed is:
1. A removable mat for association with a pavement construction of the type described and adapted to prevent accumulation of ice and snow, said mat defining a top face and a plurality of closely adjacent cells extending downwardly from said face throughout substantially the entire extent of the mat, the individual cells each having an open top, a fluid-tight bottom portion, and fluid-tight, relatively steep, upstanding wall portions, the walls of the individual cells being retained in a spacedapart relation with respect to the walls of adjacent cells,
means interconnecting adjacent cells at the top edges thereof, openings formed in said interconnecting means communicating with the space between said walls and a substance located within the cavities defined by said cells, said substance being characterized by the property of lowering the melting point of ice and snow, said cavities being at least about A inch deep to prevent significant contact by persons or vehicles on said top face With said substances within the cavities and to prevent removal of said substances within the cavities and to prevent removal of said substances from the bottom of the cavities by water running over said top face, and said cells having a horizontal dimension between about inch and one inch.
2. A method for preventing accumulation of ice and snow on streets, sidewalks, driveways and like surfaces, said method comprising the steps of providing a cellular body adapted to cover said surfaces, casting a chemical substance into the cavities formed by the cells of said body, said substance being characterized by the property of lowering the melting point of ice and snow when brought into contact therewith, solidifying said substance within said cavities and placing said cellular body onto said surface, said cavities being at least inch deep to prevent significant contact by persons or vehicles on said surface with said substances within the cavities and to prevent removal of said substances from the bottom thereof by water running over said surface and said cells having a horizontal dimension between about /8 inch and one inch, said substance being normally solid at room temperature and being liquid at elevated temperature, and wherein said casting and solidifying operations include the steps of forming said substance into a liquid by heating the substance, pouring the substance into said cavities, and cooling to room temperature to provide for solidifying of the substance within the cavities whereby said cellular body is adapted to prevent accumulation of ice and snow.
3. A method in accordance with claim 2 comprising the steps of fabricating a mat defining a top face with a plurality of depressions formed in said mat providing said cavities whereby said mat can be moved as a unit for placement on said surfaces.
4. A method in accordance with claim 2 wherein said cellular body comprises a substantially flexible material and including the step of rolling the cellular body into a compact unit for storage purposes.
References Cited by the Examiner UNITED STATES PATENTS 19,347 2/1858 Chafiee 15-25 269,480 12/1882 Stuart 945 2,555,078 5/1951 Gaylor 94*35 2,653,525 9/1953 McGuire 94-4 2,967,466 1/ 1961 Shoemaker 945 OTHER REFERENCES Roads and Bridges, October 1944, pages 67-69, 109.
JACOB L. NACKENOFF, Primary Examiner,