US2410910A

US2410910A - Material for providing traction

Info

Publication number: US2410910A
Application number: US528367A
Authority: US
Inventors: Bertrand H Wait
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-03-27
Filing date: 1944-03-27
Publication date: 1946-11-12
Anticipated expiration: 1963-11-12

Description

Patented Nov. 12, 1946 UNITED STATES A PATENT OFFICE MATERIAL FOR PROVIDING TRACTION Bertrand H. Wait, New Rochelle, N. Y.

No Drawing. Application March 27, 1944,

a Serial No. 528,367 I 2 Claims. (Cl. 117-100) My invention relates to improvements in matecause it does not penetrate the ice and is quickly.

picked up and scattered by wind, traflic or both.

On the other hand the application .of salts alone to the ice does not quickly; provide a surface which is sufiiciently rough to afford traction for motor vehicles and the high cost of such materials in the quantities necessary to produce rapid and thorough disintegration of the ice is prohibitive;

A further advance in the art was made more or less incidentally when such salts were added to stock piles of sand, screenings andthe like to prevent their freezing into a solid mass. When abrasive material with such additions is spread on the surface of the ice the salt tends to melt the ice and thus permit the abrasive particles which happen to lie closely adjacent particles of the salt to stick to said surface or become partially embedded therein. The quantity of salt usually employed to prevent the stock piles from freezing into a solid mass is not very greatand ordinarily it is merely deposited in flake form in the pile as it is built up or on top of the pile and becomes distributed more or less unevenly therethrough only as it deliquesces or as the trucks from which the material is spread are loaded from the pile. Thus, many particles of abrasive are deposited on the ice with little or nothing to facilitate their penetration and anchorage therein.

In order to prevent the freezing of stock piles of sand and to provide a free flowing material it has been proposed to treat the sand with a solution of calcium chloride. and to apply the wet material to the ice. Such a material is very heavy due to the large volume of water therein; the quantity of salt associated with each particle of abrasive is very small; and its association with the particle is brief. For these reasons sand, screenings and the like so treated are not appreciably effective in producing disintegration of the ice. Such material produces somewhat better eneral results than salts alone or abrasives alone but it does not help materially in the disintegration of the ice which is highly desirable if such a result can be obtained economically because, when disintegrated, the ice can be easily removed from .the road by scrapers.

Ordinarily the extent to which the abrasives Will become embedded in the ice is a function of the temperature andthe quantity of salt. Be-' cause temperatures vary over wide ranges it is impossible to foretell the temperature which may be encountered in any instance. When too small a proportion of salt is employed the ice is not softened sufliciently for the particles of abrasives to embed themselves and they are blown away or scattered by traffic. On the other hand, when too great a proportion of salts is employed the ice melts rapidly, the abrasives lie in Water, little traction is obtained, some of the abrasives are flushed off the surface and, eventually, the solution becomes so dilute that it refreezes with a tractionless surface and requires replacing.

The principal object of my invention is to provide an improved material for providing traction on icy pavements and at the same time to provide a material which will effectively disintegrate the ice. Another object is to provide a material of this character which is comparatively light in weight so that handling and shipping costs are reduced. A further object is to provide a material which can be economically produced, and Which will be effective over longer periods of time than the materials now employed for this purpose.

base a porous absorptive material such as slag or cinders in the form of discrete particles. Depending upon the form in which the material is available, it is either crushed and thereafter screened, or merely screened, to reject all particles which will not pass through a one-half inch square opening. A fairly large percentage of fine mat rial is preferable since such material, in the aggregate, presents a much greater surface area for the adsorption of the salts which are to be applied than the same weight of material in larger sizes, and the smaller material is more effective in initiating disintegration of the ice over a greater area. Material which is larger than about one-half inch in size is undesirable because the object is to produce a material which will not only stick to the ice but will initiate disintegration of the ice at the largest possible number of points.

If the screened material is wet Or contains any I accomplish these objects by employing as a 3 substantial quantity of moisture it is then dried, preferably by heating.

After drying, the material is impregnated and incidentally coated by treating it in or with an aqueous solution of a salt, such as calcium or sodium chloride, or both, adapted to lower the freezing point of Water. The material is preferably treated by spraying the solution on the dried particles which may be, and preferably are, still hot from the drying step. However, the solution may be poured on the material, or the material may be immersed in or run through a bath of the treating solution. The strength of the solution may vary depending upon the temperature expected to be encountered in the application. Where these temperatures are very low I prefer to use a substantially saturated solution. The particles quickly absorb and adsorb the chlorides, and the treated material may be used immediately or stock piled for future use. However, in all cases, and especially where shipping or handling costs based on tonnage are high, the material is preferably dried to effect a recrystallization, 01' at least partial recrystallization, of the salts by heating. During the drying, the material should be agitated to prevent the formation of solid masses. This can be easily done in a heater of the well known type used for heating and drying a gregates prior to incorporating bituminous materials therewith, 7

When the material is spread, the coating on the outside of the particles comes into contact with the ice and melts or softens the ice sufficiently to create pockets into which the particles embed themselves. The advantages of using an impregnated, porous, base material now becomes evident. Such material, thereafter, releases slowly the salts with which it is impregnated and offers a marked resistance to that rapid dilution of the salt solution which occurs where the abrasives are only surface treated. Since the particles are almost immediately partially embedded in the ice they are not easily scattered by Wind and traffic and, in time, work their way down through the ice honeycombing it and facilitating its removal by scrapers, or accelerating the disintegrating effects of the natural forces such as sun rays or a rise in atmospheric temperature.

Calcium chloride gives much quicker action than sodium chloride and hence there is some advantage in treating the material with a solution of each separately or together, thus obtaining the quick action of the calcium chloride for immediate contact with the ice and the slow action of the sodium chloride contained by the aggregate for the rotting of the ice. Thus, assuming for example, that a water cooled pulverized slag, which is very porous, is the material treated: After screening I may first impregnate the slag palticles with a solution of sodium chloride or a mixture of sodium and calcium chloride, dry them, and thereafter lightly spray the particles with a solution of calcium chloride, thus providing on the surface of the particles a small quantity of a substance which acts quickly to anchor the particles to the ice and, at the same time, providing a slower acting material in the sodium chloride which effectively rots the ice and gradually e beds the particles therein.

As a general rule the solutions used will be highly concentrated salt liquids which will be absorbed by the particles and provide a maximum proportion of the salts per ton of material, thus doing away with high cost of shipping and handling to obtain satisfactory results.

It will be apparent that by using a substantially saturated solution, which may be heated to increase the quantity of salt which can be carried thereby, and then applying it to heated particles of any water insoluble material, such as stone screenings, any cooling of the treated material or any evaporation of the Water from the material, as by a hot drying process, will effect a precipitation of some of the salt on the articles. Thus, a material is provided having a coating of a salt thereon at least partially in solid or crystalline form which will be particularlyeffective, irrespective of the degree of impregnation because substantially all of the salt will be concentrated on the particles where it will function to anchor them individually in the ice.

What I claim is:

1. The method of forming a material for providing traction on icy pavements which comprises impregnating a hard, porous water-insoluble substance in the form of discrete particles with sodium chloride by treating said particles in a solution of said salt, drying said particles to effect at least a partial recrystallization of said salt, and thereafter spraying said particles with a, solution of calcium chloride.

2. The method of forming a material adapted to provide traction on icy pavements upon its application thereto which comprises impregnating porous slag in the form of discrete particles with a hot saturated solution of calcium chloride and thereafter cooling said particles to effect a precipitation and recrystallization of said calcium chloride in and on said particles.

BER'I'RAND H. WAIT.