US2618576A

US2618576A - Sheets-xsheet i

Info

Publication number: US2618576A
Authority: US
Publication date: 1952-11-18
Anticipated expiration: 1969-11-18

Description

Filed NOV. 12, 1948 2 SHEETS-SHEET 1 NOV. 18, 1952 w. G BROWN ET AL METHOD OF COATING SURFACES WITH CEMENTITIOUS MATERIAL INVENTORS 14 4/7291? 6. 2 7v); BY Wdrlen ,H Bran 7 h ATTORNE Y5 1952 w. G. BROWN ET AL 2,618,576

METHOD OF COATING SURFACES WITH CEMENTITIOU$ MATERIAL 2 SHEETS SHEET 2 Filed Nov. 12, 1948 E. E u 705 0.9

.m g -ATTORNEY terial to a surface.

Patented Nov. 18, 1952 UNITED STATES PTENT OFFICE METHOD OF COATING SURFACES WITH CEMENTITIOUS MATERIAL Application November 12, 1948; Serial No; 59,726 8. Claims. (01. 117-404) The invention relates generally to painting or coating'surfaces and it has particular relation to a method of applying liquid cementitious ma- This application is a continuation-in-part of applicants conending applica tion, Serial Number 467,680, filed December 3, 1942, now abandoned.

The application of liquid cementitious material heretofore has involved particular difiiculties where the material includes a substance such as Portland cement. Application of a material of this character by brushing it on to a surface requires tedious manual effort, especially if the operator desires to obtain a smoothly distributed coating. Another factor which contributed to the inefiiciencies' and diificulties of manually applying the material in this manner was that the ingredients would not stay uniformly mixed and hence the coating would vary accordingly.

Another factor which contributed to the inefiiciency and undesirability of the practice heretofore, whether by hand or by spray gun, was that the coating after setting and hardening would have minute cracks caused by shrinkage. This not only damaged the coating itself but it resulted in a relatively poor appearance. In other words, the coating did not have that solid, unitary appearance and structure which always is desiralale in a surface coating.

During the mixing of concrete. the cement particles take up water by crystallization in a process known as hydration and form a cementing gel which, when it sets, serves to bind the aggregates'together. The above mentioned hairline cracks result in cementitious coatings mixed in accordance with previously known practices because of the fact that in such mixing insufiicienthydration of the cement is ef ected during the 'mixing. The partial hydration resulting from such mixing permits exce sive evaporation of water duringthe setting of the concrete and the above mentioned hairline cracks result. These cracks, even though very fine. greatly accelerate weathering and accompanying deterioration'o f' the concrete One'object'of the present invention is'to provide a methodof mixing and applying cementitious material in liquid form which overcomes the disadvantages mentioned and results in a uniform, smooth strong surface coating.

Another object of the invention is to provide amethod of mixing and applying acementitious, liquid-coating, wherein improved and-bettter hydrationbf'ithe cement particles is obtained;

Another objectof the'invention is-to provide a method of mixing andapplying liquid; cementitious materialwhich will result in a coating substantially free from cracks normally caused by shrinkage of the material during setting.

Another object of the invention is to providean improved method of mixing and applyinga cementitious coating which will result in more uniform mixing of the material as it is appliedto the surface. s

Another object of the invention is to provide a method of mixing and applying liquid cementitious material which will allow continuous operation so that an operator handling a spray gun for instance may continue to apply the material for an indefinite period of time Without interruption.

Another'object of the invention is to provide an improved method of mixing and applying a liquid cementitious material permitting effective coatin of surfaces disposed at an elevation'considerably above that of the mixing apparatus employed.

Other objects of the invention will become apparent'from the following specification, from the drawings related thereto, and from the claims hereinafter set forth.

For abetter understanding of the invention, reference may be had to the drawings, wherein:

Figure 1 is a sideelevational-view'of apparatus constructed according to one former the invention;

Fi ure 2 is a planview of the apparatus shown by Figure'l;

Fi ure 3 is a view showing a vertical section'of the tank'seen at the left in Figures 1 and 2;

Figure l is asim lar; vertical section of the tank seen at theright in Figures 1 and 2;

Fi ure 5' is a cross-sectional view taken substantially alongthe' line 55 ofFigure 3;

Figure 6' is a cross-sectional view taken substantially along the line 6-6 of Figure 4; and

Figure 7 is a cross-sectional view of a valve employed in the conduit connecting the'tanks.

Referringtol i ures 1, 2, and 4:, the apparatus includes a bed frame if] supported on a pair of rear wheels II and a front steerable wheel l2 having a handle I3 for moving the apparatus from oneplace to'another. A mixing tank I5 is supported on the bed lu'by legs It, and, as best shown .by Figure l, the upper end wall ofthe tank'has an opening I! through whichthe lower end-of a hopper ill-projects. The hopper and upper end wall 201 .the-ftankvmay be welded Ito;

getlier aroundthe edge-"of the opeiiingtso as-to obtain a rigid as well as sealed joint. A cover 20 is provided at the lower end of the hopper and is pivotally connected thereto at one side, as indicated at 2i. This cover is adapted to be moved upwardly and it carries a sealing ring 22, which in turn is adapted to abut an inwardly turned flange 23 on the lower edge of the hopper. For moving the cover 20 upwardly, a link 24 is pivotally connected, as indicated at 25, to a projection 26 on the cover and this link in turn at its upper end is rigidly fastened to a pair of toggle straps 28. The straps in turn are pivotally connected, as indicated at 29, to a gooseneck lever 30, which is in turn pivotally connected at an intermediate point 3| to a bar 32. This bar is rigidly fastened as indicated at 33, to the tank, and may be similarly fastened or welded to the side of the hopper. When the lever 38 is swung clockwise, as seen in Figure 4, the straps 28 and link 24 will be so moved as to open the cover 28 and it should be noted that when the parts are in the closed position, it is necessary first to break the toggle through movement of the lever before the cover 20 can open.

The mixture or coating to be used may comprise an argillo calcareous substance such as Portland cement, finely divided sand, and water, although it should be understood that other ingredients such as waterproofing agents may be added, or that the mixture may comprise various other combinations including Portland or similar cement. One part cement, three parts sand, and enough water to provide the required liquid condition may be used for instance and these ingredients are placed in the tank in proper proportions and then the cover 20 is closed.

For agitating and mixing the materials in the tank, a rotary shaft 31 extends upwardly through the bottom wall of the tank and this shaft is keyed to the upper end wall 38 of a sleeve 39 having radially projecting elements 40 at spaced points thereon for stirring the materials in the tank. These elements move in between other and stationary elements 4| fastened to the inner side of the tank, and from this it will be appreciated that thorough stirring and mixing of the material may be obtained. The shaft 31 is rotatable in a stationary tube 42 fastened tightly in the bottom wall of the tank by threaded nuts 43 and 44 disposed respectively at the lower and upper sides of the wall. At its upper end the tube 42 has a thrust bearing 45 which engages the end wall 38 in the sleeve and a nut 48 on the upper end of the shaft 31 retains the sleeve 39, tube 42, and shaft assembled.

Below the bottom wall, a bevel gear 50 is keyed to the lower end of the shaft, and thi gear substantially abuts a packing gland i threaded on the lower end of the tube 42. A nut 52 is provided on the lower end of the shaft for holding the gear in place and it will be noted that a grease fitting 53 is provided which communicates with a central passage 54 in the shaft leading to the external surface of the latter, from which it follows that the outer surface of the pin may be lubricated.

For sealing the sleeve 39 relative to the tube 42, a collar 55 is fastened to the interior of the sleeve adjacent its lower end, and while this collar does not have sealing engagement with the tube, it acts as a shoulder against which a rubber sealing sleeve 56 may press. Pressure within the tank tending to force the rubber sleeve 56 upwardly in the sleeve 39 acts to force the rubber against the collar 55 and expand the rubber 4 into sealing engagement with the tube 42, from which it will be seen that leakage of material in the tank upwardly along the tube 42 will be prevented.

For rotating the shaft 31, a second bevel gear 66 meshes with the gear 50, and this second bevel gear is fastened to a shaft 6| which, as best shown by Figure l, is connected to a reduction gearing box 62. The reduction gearing is connected to a shaft 63 of a motor 64, and from this it follows that the agitator and mixer within the tank 15 may be rotated at a desired speed.

With respect to mixing of the materials in the tank 15, it has been found that faster and much greater hydration of the cement particles occurs if the mixture is maintained under substantial pressure. Where no pressure on the materials is provided, considerable time is required for the cement particles to take up water in hydrating and furthermore the hydration is not complete. During hydration, or taking up of water, the cement particles increase in volume, and where insufiicient hydration has occurred, it has been found that during setting of the coating after it is applied to a surface, the particles shrink and leave fine, hairline cracks. Where the materials are maintained under substantial pressure during mixing and agitation, it has been found that more water is forced into the particles, more hydration of all particles occurs and that hydration is effected more rapidly. This result in less shrinkage in setting and the fine, hairline cracks previously obtained are practically eliminated. This is for the reason that the release of water which has been taken up as water of hydration requires a definite amount of energy and normal weathering does not supply sufficient energy to effect the release of any substantial proportion of this water of hydration. On the other hand, water in the free condition in which much of it exists when the material is mixed by previously known methods may readily evaporate and cause shrinkage. As an instance of pressure which has been found desirable for obtaining these results, an air line pressure of approximately 100 pounds per square inch may be used.

Now referring to Figures 1 and 2 again, an air pressure line 10 is provided which leads to a pressure reducing valve H. A gauge 12 connected to the high pressure side of the valve H by a conduit 13 indicates the line pressure supplied to the valve. A conduit 14 also connected to the high pressure side of the valve has a manually operable valve 15 therein and this conduit leads to the tank 15. With a line pressure in the line '10 of approximately 100 pounds per square inch, it is apparent that this pressure may be applied to the materials in the tank 15 and that the line may be cut off at any time by means of the valve 15.

After the material is mixed under pressure in the tank l5, it may be conducted through a conduit T! to a second tank 18 also mounted on the bed I0. As best shown by Figure 7, the conduit I! includes a sleeve containing a rubber tube 8| which is adapted to close the conduit to passage of fluid therethrough when the tube is collapsed at its center. For collapsing the tube, a plunger 83 is mounted in a small cylinder 84 welded to the side of the sleeve 80 and this plunger is adapted to be moved downwardly against the wall of the tube 8| by air pressure at the upper end of the plunger. A spring 85 is adapted to return the plunger to its inoperative position upon release of the pressure.

Referring again to Figures 1- and 2, the small cylinder 84 containing the plunger 83 is connected to an air pressure line 81 which in turn is connected tothe low pressure side of the reducing valve -'H. A manually operated valve 88 is provided in the line 81 so that the pressure maybe out off from the cylinder 84 and it might be mentioned .inthis connection that a suitable exhaust vent may be provided in the valve 88 so that when the valve is closed, air in the lower part .maybe readilytreleased. Each .of' thesefastening means includes a threaded shank 9| pivotally connectedasindicated at 92 to'the side wall of the tank: and whichmaybe moved into a slot 93 in the-edge of the cover. A wing nut 34 on the end of the shank is adapted to be drawn tightly against the cover so as to hold it in closed position. A sealing element 95 between the edge of the cover and a flange St on the tank serves to seal the tank against leakage.

In order to continually agitate the liquid coating material in the tank '13, an agitator is provided whichv includes a shaft .93 journaled in a bearing. element '95 fastened in the cover fill and inza lowerbearing element Illll fastened to a strap Nil having its ends welded to the underside of ,th'e'cover. Collars' I02 above and below the'strap I! and fastened to the shaft, serve to support and locate the later vertically. Blade elements Hi3 fastened to the shaft 98 serveto agitate the material whenthe shaft is rotated.

Above thecover, a packing gland Hi l is thread- .ed onto :the' bearing element'flil so as to prevent leakage along the shaft and the upper end of the shaft'has'a bevel gear Hi5 which meshes with a second gear I 06. The latter gear is mounted on ashaft l0! which, as best shown by Figure 1. isrotatably mounted in'a U-shaped bracket I88 Welded'to the cover 98. The opposite end of the shaft It"! hasa bevelgear Ili9'which meshes with a bevel gear Ht! mounted on the upper end of a shaftlrll. At its upper end; this shaft is turnablysupported in a bearing H2 fastened to a bracket I [3 in' turnfastened to the side of the tank while the lower end of the shaft is journaled in a bearing I I5 fastened by bolts 1 It to a plate Iii! in'turn fastened to the side members of the bedl 9. :A bevel gear I on the lower end of'the shaft H limeshes with a bevel gear 52! mounted directly on theopposite end of the motor shaft 63. The agitator in tank 18 therefore may bedrivenat a fasterrrate of speedthanthe agita to-r in the tank'l5.

In'order toispraytheliquid mixture in tank 53 onto a surface to'be coatedya conduit H5 is connected to the-bottom portion of the tank and this con tuit leads'to'a spray'gun I25. This spray gun may .be'of the type shown in our United States Letters-:PatentNo. 2,305,840, granted December 22, l94-2 andibriefly includes a'rubber'itype valve onthe orderqshown'byFigure '7 whichist'normally held in'a-collapsed orclosed-position by air pressure-delivered by a conduit I21 connected to the cylinder I28 of the valve and to the low pressure side of the reducing valve H. A valve 129 having-a trigger [-30 may be used to open and .close theconduit l'2'l andthus close-and open-the'gun. It will be appreciated, however, that the plunger 6 for closing the rubber valve might be held in a closed position by spring pressure and that a similar trigger might be used for moving the plunger and opening the valve.

For supplying a pressure to the liquid in tank iii, a conduit I3! is connected to the low pressure side of the reducing valve ll and this conduit in turn is connected to a conduit I32 conneoted to the upper part of the tank 18. A manually controlled valve I33 in the conduit l32 enables cutting off the air pressure from the tank.

In using the apparatus described, the proper ingredients are placed in the tank IE, it being understood that the valve i5 is first closed and that the valve 88 is open so that the rubber valve in conduit Tl is closed. Then the cover 2!] is closed, air line valve 55 is opened, and the motor 65 is started so as'to mix the material under pressure. As before stated, better and morerapid hydration of the cement particles is obtained. by this pressure. After themixing for a sufficient time, the valve 88 may be closed so as to open the conduit 11 and then the mixture is forced by the air pressure above it in tank It; into the tank i8. After the liquid material has been transferred to tank T8, the valve 88 is again opened so as to close the conduit Ti and the valve l 32 then may be opened if not opened previously, to place the liquid mix in tank 18 under the reduced air pressure. Following this the spray gun may be used for applying the liquid to the surface to be coated. It might be mentioned at this time that normally a pressure in tank 18 of about sixty pounds is found desirable and hence a differential of approximately forty pounds exists betwen the two tanks. This differential permits the transfer of the mixed material from the mixing tank [5 to the spraying tank 1'8 in the manner above described. It will be appreciated that the amount of differential required, betwen the pressures in the tanks [5 and it, will vary depending upon the consistency of the mix and the size of the conduit ll. It has been found desirable to have this pressure differential be at least twenty-five pounds per square inch.

The above mentioned sixty pounds pressure in the spraying tank '38 may also vary considerably depending upon numerous factors such as the size and length'of the conduit I25 and the elevation of the spray gun I26 above the level of the material in the tank It. By way of example, it has been found that with a three-quarter inch hose one hundred feet long, a pressure of at least thirty pounds per square inch plus three-quarters of a pound per square inch for each foot of elevation of the spray gun above the level of the material in the tank 18, is required to insure proper delivery of the mixed material from the tank '13 to the spray gun I26.

It will be appreciated of course that in spraying surfaces at great elevations above the tank 18 it may be necessary to employ a pressure within the tank iii considerably greater than the above mentioned pressure in the mixing tank l5. In such cases it will be understood that the pressure within the tank vI 5 may be considerably more than one hundred pounds per square inch in order to provide the desired differential between the-pressures in the tanks l5 and i8.

While the operator is using the spray gun and applyingthe liquid in tank '58, a second operator may close the air valve 75 and'exhaustair in the tank l5 by means of a pipe I35 and valve :36. ihen while theoperator is ;,spraying with. liquid intank 18, a new mix may beplacedvin the tank and prepared. This new mix may be transferred to tank 18 at any time and even during operation of the spray gun, since it is only necessary to close valve 88 to open conduit Ti and then the differential in pressure will force the mix from tank It into tank 18. This manner of operating the equipment may be continued indefinitely and continuous spraying may thus be efiected.

When it is desired to clean the equipment, the covers may be removed and the tanks filled with water and then the covers replaced. Following this, the water in both tanks may be agitated and the solution then evacuated completely through the spray gun by air pressure. Incidentially, this cleaning of the tanks also cleans the spray gun and the conduit leading to the latter. It might be stated too that if desired, water pipes having valves therein may be connected to both tanks so as to supply water thereto when desired and particularly to fill the tanks for cleaning. In this event opening of the covers would not be necessary to place water in the tanks. It may be added that an air escape valve might be provided too on tank is so that when desired this tank could be opened to the atmosphere so as to allow air under pressure therein to exhaust.

The apparatus and the method enable obtaining greater and faster hydration of the cement particles due principally to the fact that the mixing is effected under high pressure which forces the water into the cement particles more rapidly and more thoroughly. This is reflected in a better finish or coating which will not crack and which will not shrink at least nearly as much as shrinkage occurred in connection with prior practices. Since the entire apparatus is mounted on a movable bed, its use is greatly facilitated and it will be understood that air lines and water lines will be flexible to permit movement of the apparatus away from sources of air and water.

Although only one form of the invention has been illustrated and described in detail, it will be apparent to those skilled in the art that various modifications may be made without departing from the scope of the appended claims.

What is claimed is:

1. The process of coating a surface with a liquid cement including argillo-calcarecus substances, whioh comprises mechanically finely pulverized argillo-calcareous materials with water in a closed tank for hydrating the materials while maintaining the mixture under a generally static air pressure of about onehundred pounds per square inch, and then applying the mixture to such surface while the mixture is in fluid form.

2. The process of coating a surface with a liquid cement including argillo-calcareous substances, which comprises mechanically mixing finely pulverized argillo-calcareous materials with water in a closed tank for hydrating the materials while maintaining the mixture a generally static air pressure, of about one-hundred pounds per square inch, then spraying the liquid mixture onto such surface while such mixture is in fluid form under a pressure of about sixty pounds per square inch.

The process of coating a surface with a liquid cement including argillo-calcareous substances, which comprises mechanically mixing finely pulverized argillo-calcareous materials with water in a closed tank for hydrating the materials while maintaining the mixture under a generally static air pressure of at least one-hundred pounds per square inch, and then applying the mixture to such surface while the mixture is in fiuid form.

4. The process of coating a surface with a liquid cement including argillo-calcareous substances, which comprises mechanically mixing finely pulverized argillo-calcareous materials with water in a closed tank for hydrating the materials while maintaining the mixture under a generally static air pressure, of at least onehundred pounds per square inch, and then spraying the liquid mixture onto such surface while such mixture is in fluid form and under a pressure of at least sixty pounds per square inch.

5. The process of mixing and apply a liquid cement which comprises utilizing two closed tanks having a connection for transferring mixture from one to the other, mechanically mixing finely pulverized argillo-calcareous materials with water in one of the tanks while maintaining the mixture under a generally static air pressure of at least one-hundred pounds per square inch, then transierring the mixture to the second tank by means of the pressure in the first tank and then closing the connection between the tanks, maintaining the mixture in the second tank under an air pressure above atmospheric but below the air pressure in the first tank and using this pressure in the second tank to apply the mixture to a surface to be coated.

6. The process of mixing and applying a liquid cement, which comprises utilizing two closed tanks having a connection for transferring mixture from one to the other, mechanically mixing finel pulverized argillo-calcareous material with water in one of the tanks while maintaining the mixture under a generally static air pressure of at least one-hundred pounds per square inch, then transferring the mixture to the second tank by means of the pressure in the first tank and then closing the connection between the tanks, maintaining the mixture in the second tank under an air pressure above atmospheric but below the air pressure in the first tank, using this pressure in the second tank to apply the mixture to a surface to be coated, and simultaneously mixing new materials in the first tank While applying the mixture from the second tank.

7. The process of coating a surface with a liquid cement including argillo-calcareous substances, which comprises mechanically mixing finely pulverized argillo-calcareous materials with water in a closed tank for hydrating the materials while maintaining the mixture under a generally static air pressure of at least onehundred pounds per square inch, then transferring the mixture to a second closed tank by means of the pressure in the first tank while maintaining the second tank at a pressure above atmospheric but below the pressure in the first tank and suitable for supplying the mixture through a suitable line to the highest portion of the surface to which the material is to be applied, then applying the liquid mixture to such surface while the mixture is in fluid form.

8. The process of coating a surface with a liquid cement including argillo-calcareous substances which comprises mechanically mixing finely pulverized argillo-calcareous materials with water in a closed tank for hydrating the materials while maintaining the mixture under a generally static air pressure of at least onehundred pounds per square inch, then transferring the mixture to a second closed tank by means of the pressure in the first tank while maintaining the second tank at a pressure suitable for supplying the mixture through a suitable line to the highest portion of the surface to which the material is to be applied, said pressure in said second tank being at least equal to thirty pounds per square inch plus three-quarters of a pound per square inch for each foot of elevation of said highest portion of said surface above the level of the mixture in said second tank.

WARREN GILBERT BROWN. WARREN DURAND BROWN.

10 REFERENCES CITED The following references are of record in the file of this patent:

5 UNITED STATES PATENTS Number Name Date 1,506,089 Schuster Aug. 26, 1924 1,751,343 Mack Mar. 18, 1930

Claims

2. THE PROCESS OF COATING A SURFACE WITH A LIQUID CEMENT INCLUDING ARGILLO-CALCAREOUS SUBSTANCES, WHICH COMPRISES MECHANICALLY MIXING FINELY PULVERIZED ARGILLO-CALCAREOUS MATERIALS WITH WATER IN A CLOSED TANK FOR HYDRATING THE MATERIALS WHILE MAINTAINING THE MIXTURE UNDER A GENERALLY STATIC AIR PRESSURE, OF ABOUT ONE-HUNDRED POUNDS PER SQUARE INCH, AND THEN SPRAYING THE LIQUID MIXTURE ONTO SUCH SURFACE WHILE SUCH MIXTURE IS IN FLUID FORM AND UNDER A PRESSURE OF ABOUT SIXTY POUNDS PER SQUARE INCH.