US2568678A - Apparatus for handling mixed concrete - Google Patents

Description

E. D. ALESSIO APPARATUS FOR HANDLING MIXED CONCRETE Sept. 18, 1951 2 Sheets-Sheet 1 Filed July 15, 1950 I N V EN TOR.

[way To 3/41. E53 IO Sept. 18, 1951 E. D. ALESSIO APPARATUS FOR HANDLING MIXED CONCRETE Filed July 15 1950 2 Sheets-Sheet 2 INVENTOR fkzves 70D 4668/0 7 ATTORNEY Patented Sept. 18, 1951 OFFICE APPARATUS FOR HANDLING MIXED CONCRETE Ernesto n. lllesslo; Akron, Ohio Application July 13, 1950, Serial No. 173,556

3 Claims. flci. 259178) I This invention relates to the handling of mixed concrete. More particularly, it relates to an im-' proved method for maintaining the concrete in a fluid, pourable condition while transportingit to a construction site where it is to be poured. The invention includes a preferred apparatus for carrying out the method. a

Concrete for ordinary construction purposes .is

commonly prepared at a centrally located plant wherethe proper proportions of Portland cement, water, and aggregate are carefully measured for is equipped with means to agitate the concrete. in transit to prevent it from setting before it is poured. Some vehicles are equipped with means for mixing the concrete as well as agitating the mixed material. the vehicle is adapted to be operated at two different speeds, one for mixing and one for agitating the mixed material.

The usual vehicular equipment includes a horizontal cylindrical tank (or tank of other shape) provided with means for rotating it on a horizon-.

tal axis. The rotation of the tank mixesthe .concrete or slowly agitates it after mixing. Such tumbling or other violent agitation is harmful to. the concrete because it strips the cement paste from the aggregate, and after setting, concrete which has been thus violently agitated during' transportation to the construction site has a lower strength than if it had'not been agitated Stirring is not as harmful as tumbling or the like, and does little or no damage to a thoroughly.

mixed concrete.

Concrete which has been tumbled in transit solidifies very rapidly. This makes it difficult to handle. Concrete which has been merely stirred in transit does not solidify so rapidly, other conditions being comparable. It is therefore more easily handled. 1

Heat is liberated as the cement in the concrete is hydrated and as the concrete solidifies.

heating has a tendency to vaporize and drive off a portion of the water not yet combined with the cement. This loss may be compensated for in the water-cement ratio when the mix is prepared, but'a certain amount of heat is generated by the tumbling, due to the striking of the aggregates against one another, etc., and this cannot be accurately predicted. As a consequence, it is Often the agitatingmeans on.

impossible to calculate the amount of water which will be lost during tumbling, and there is no way of accurately compensating for it. This in itself is a serious objection to the ordinary method of agitating the concrete while transporting it.

According to this invention the concrete is mixed at a central plant where the necessary water is mixed with the other ingredients. The various ingredients are thoroughly mixed. The mixed concrete is then transferred to a tank or other container on a suitable vehicle, such as a truck. Means is provided for slowly stirring the concrete while itis being transported, without tumbling it- The stirrer merely displaces the various particles of aggregate in the fluid or plastic mass of the concrete mix from time to time so as to prevent the mass from solidifying. The preferred stirrer reciprocates slowly back and forth through the plastic mass. This stirring action continues from the time the vehicle is loaded until the concrete is ready to be poured. It has no appreciable efiect upon the temperature of the concrete or the amount of water vaporized from it.

The preferred stirrer of this invention may be readily installed on any vehicle equipped with a truck body suitable for hauling liquid. It is readily installed on any conventional dump truck. It includes one or more horizontally disposed stirring bars which are immersed in the concrete and are reciprocated back and forth through the concrete by power means which is preferably driven by the motor or the truck. Preferably, the forwardand rear edges of the stirring bars are relatively sharp and the top and bottom surfaces of these bars slope gradually away from both edges. As the bars are moved through the concrete they tend to displace some of the particles of the mix upwardly momentarily, and the particles then sink back of their own accord.v

This prevents the aggregate from settling toward the bottom of the mix. The stirring is preferably effected with minimum change in the composition of the material on the surface of the concrete. The movement of the particles of the aggregate is slight, but sufficient to prevent the batch from solidifying.

The improved method and the preferred apparatus will be further described with reference to the drawings, in which- Fig. l is a side elevation of a dump truck body with the preferred apparatus installed thereon; Figs. 2 and 3 are cross-sectional detail views of element for the equipment shown includes the.

three bars l, 2 and 3. These stirring bars are bottom. As shown in Fig. 5, the crank 30 is located at the center of the shaft and the shaft is supported below the bottom of the body by suitable bearings 35.

The ends 31 of the shaft project outwardly a short distance at each side of the body and a flat bar 38 is rigidly fastened around each end 3! by a key 4|]. Each bar 38 extends upwardly from the .shaft close to its respective .sid ,of the body and its upper end is pivotally connected by a rivet 42 to the end of another flat bar 33. The

rivet 42, as shown in Fig. 3, extends loosely disposed horizontally with one spaced vertically above the other.

They are supported at their ends by the vertical uprights 4, 4. Reinforcing ring bars, as shown in Fig. 2. These rods are preferably formed with a diamond-shaped cross section but they may be round.

Each of the upper stirring bars has a diamondshaped .cross section, as shown in Fig. 4. The forward edge 1 and the rear edge, 8 of these bars are sharp, and the top and bottom surfaces 9 taper backwardly from each edge with a fairly low slope. The taper of each sloping portion of the top surface is preferably less than thirty degrees. The lowest stirring bar 3 has a triangular cross section. 'Its forward and rear edges are sharp and its top surface is tapered similarly to the bars I and 2, but the bottom of bar 3 is flat.

The stirring element fits inside the body II of the truck so that the stirring bars extend laterally across thebody substantially parallel to the bottom of the truck. The uprights 4, 4 are located close to the sides of the truck and the lowest stirring bar 3 is located just above the bottom of the body. The upper ends of the uprights 4 pro-' ject above the top of the sides of the body somewhat and a bar I2 is welded across the upper ends of these uprights. The portions l3 at each end of the bar l2 project out across the top' edge of the sides of the body and a flat plate is welded to each end l3. The plates I5 are relatively wide, as shown in Fig. l, and they extend vertically downward parallel to the uprights'd but of the sides of the are along the outside surface truck.

A pair of rollers I8 is mounted on the inside surface of each plate I 5 near the corner 19- formed where the plate I5 is welded to the end l3 of the bar I2. The rollers t8 extend inwardly toward the sides of the body. adapted to roll in a track 29 located along the top of each side of the body. Each track 29 is preferably a length of channel iron which rests on the outwardly turned flange 22 along the top of the sides of the body and extends from the front to the rear of the body. The channelsare positioned with their legs projecting horizontally outwardly to receive the rollers it which roll back and forth on the legs when the stirring element is moved through the concrete in the body.

The reciprocating action may be obtained by a variety. of different structures. Preferably a fluid 7 pressure cylinder 23 is employed tosupl ly. the

power required to reciprocate the stirring element. The cylinder 23 is operated from the hydraulic system which normally operates cylinder 24 which raises and lowers the body. Cylinder 23 is pivotally mounted at 28 under the bottom of the body. The outer end of its piston rod 29 is fastened to a crank 33 which is rigidly connected to and projects downwardly from a shaft 32 which extends laterally across the body under its Each pair isthrough the upper end of bar 38 and the abutting end of lbar 13, and is held in place by cotter pin 1:5. 'Bar 43 slopes downwardly toward the rear of. the body and its lower end is pivotally engaged with the downwardly extending plate l5 by a rivet l8 whioh-ex tends through bar 43 and through a hole .49 (Fig. 2) in plate [5. The rivet is removably fastened in place by cotter pin 50.

Fig. 1 showsthe relative position of the bars 38 and '43 in solid lines when the stirring element is at the rear .of the .body next .to the tailgate. The broken lines indicate therelat'ive position of these same bars when the .st'irring element :is shifted toa position near the front end'of the body. To move the stirring. element from the rear of the body to the forward position shown, fluid is introduced into the cylinder23 soth at its piston rod 29 is retracted into the cylinder. (See Fig. 6;) the crank toward the rear of the truck thereby rotating the shaft 32 to swing the bars '38 on each end of the shaft forwardly toward the cab. The movement of the bars '38 shifts the bars 43 forward so that the stirring element'is pulled toward the front of the body." Rollers 1-18 rollv along the track 20 as the stirrirrg element isv When the stirrer reaches the front of the body.

the valve apparatus 55 operates to reverse the flow of fluid -into the cylinder '23 so that the piston 29 is forced out of the cylinder and crank 30 is swung forwardly toward the cab. This rotation of shaft 32 swings the bar's38 backwardly so that the bars 43 push the stirring bars toward the rear of the body. While the concrete is being hauled in the truck the stirring bars are constantly reciprocatedfrom one end of-the truck body to the other in the manner described.

' The hydraulic apparatus for operating the cylinder 23 is not illustratedin'detail since such systems are well known. Valve 55 is preferably a solenoid-type valve whose action is controlled by the limit switches 56 shown in Fig. 6.- Preferably these switches are positionedso that their followers 58 and 59 roll on the peripheral surface of the hub 58. of crank 36. 1 The. studs 60 and 6| are embedded in the surface of hub 58 in the path of the followers. As .the crank 30 isswung to its most forward position, stud 60 moves into contact with the follower' 58 whichcloses its switch 56. This energizes the solenoid valve-55 which then operates to cut off the fluid flowing against one side of the piston inside the cylinder 23 and permits the liquid to flow into the cylinder against the opposite side of the piston thereby swinging the crank backward. At the rearmost position of the crank, stud Bl contacts the follower 59 so that the solenoid is again energized and the movement of the piston rod is reversed. Each Qfth pl tes '5 is p ovided .w h s v The movement of rod 29 swings holes such as holes 63 and til-between the hole 49 andthe rollers I 8. The pin 48 may be-re moved from hole 49 and inserted into; one of see he z 119165 q t a tnelena of the bar 43 m ay be; fastened at anyone of several different positions on plate .-l -to-vary the point from v which: the stirring element. is pulled. Ordinarily the end of the bar 43;,is connected to pull at;about the centerof theiload of concrete -t t. the is n te denc tt t h i e o wa .0 ae ward. a it m e ou h the concrete.

Preferably the body will be filled with concrete to a point just above the upper stirring bar so that this bar is moved back and forth through the concrete just below the surface to prevent a crust from forming on the surface. If the stirring element is not completely submerged in the concrete the vertical posts 5 between the bars will prevent a crust from forming on the surface.

The stirring element is moved back and forth through the load of concrete with a slow, regular reciprocating motion. As it moves forward the sharp forward edge 1 of each stirring bar plows through the concrete. The upper tapered surfaces 9 displace particles of aggregate, etc. in the concrete upwardly and prevent their settling to the bottom. 0n the backward movement the edges 8 and the tapering surfaces 9 above them produce the same effect.

This stirring action is considerably different from the conventional tumbling agitatingmovement. There is no grinding or pulverizing of the aggregate which tends to strip the paste coating from the aggregate. The concrete may be stirred for considerable periods without becoming overmixed. This prevents the segregation of the components of the concrete and the concrete is maintained at the desired plasticity until it is ready to be poured into the forms at the construction site.

Concrete mixtures differ from one locality to another depending upon whether the aggregates are smooth or sharp edged, and experts even recommend different mixtures using the same aggregate. Applicant is therefore not to be limited to any particular mixture, but suggests as illustrative a 1-2-4 mixture, meaning a mixture in which the weights of Portland cement, sand and aggregate are used in the ratio of 1:2:4. The water used will vary depending upon various factors, including the amount of moisture in the sand and aggregate. One may use, for instance, about 24 gallons of water, more or less, per yard of dry mixture.

After thorough mixing in a standard mixer, the composition is transferred to a truck equipped with a. stirring element of the type illustrated in the drawings. The inside dimensions of the body I!) of the truck are about 6%; feet wide by 10 feet long and 24 to 30 inches high. This will hold about four. to five yards of the mixture. The bottom bar is about 1% inches above the bottom of the body of the truck, but this distance may be varied, and is preferably only slightly farther from the bottom of the truck than the greatest distance through the aggregate. The stirring element is moved back and forth at the rate of one complete cycle in about two minutes. This speed is preferably variable so that it can be increased for longer and heavier hauls. The stirring element may be designed so that the lower bar is adjustable to a position close to the bottom of the body or to a position further above the bottom to accommodate different sizes of aggregate. The bars above the bottom bar may also be designed to be tilted forwardly and backwardly. A suitable water tank may also be provided with this equipment. The tank maybe installed on the truck at a convenient location so that" water may be added to a mixture from time to time as it may be required. This supply of water is also useful for rinsing out the body after a load of concrete is emptied.

The concrete mixture can be dumped from the truck at the construction site by raising one end of the truck body. The amount of water should not be so great as to give a slump of more than two inches when the mix is dumped at the construction site. A slump of one to one and one-half inches is preferred, Slump is measured according to A. S. T. M. designation C 143-39.

The preferred equipment is simple, easily fabricated, and is easily installed on the body of a conventional truck or dump truck. It may also be installed on railroad gondola cars and other vehicles. The parts are easily replaceable and no precision work is required. The equipment is considerably more economical than the very expensive rotary agitators for which special trucks are built. A further advantage in this equipment is that it does not limit the use of the truck on which it is installed to the sole purpose of hauling concrete because when the agitating element is in its forward position against the front of the body the truck may be used to haul dirt, tile, etc.

The term Portland cement is used herein to include fast-setting modifications of the original type of Portland cement.

The apparatus is not limited to the particular design disclosed. The invention is defined in the claims.

What I claim is:

1. In combination with a truck body capable of containing liquid concrete, a track fastened along each side of the body, rollers to roll on said tracks, upright members supported by the rollers and located in the body and close to the two sides thereof, and stirring means which is supported by the uprights and extends substantially from one side of the body to the other and close to the bottom of the body from one side thereof to the other as well as a substantial distance above the bottom; and driving means for reciprocating the rollers, upright members and stirring means from one end of the tracks to the other.

2. The combination of claim 1 which includes downward extensions outside of the truck body from the respective upright members, drive means connecting the same to a shaft located below the body of the truck, a fluid pressure cylinder and drive means connecting the cylinder with the shaft for turning the shaft first in one direction and then in the other as the plunger of the cylinder moves in and out thereof, thereby moving the stirring means back and forth in the truck body by means of said first-mentioned drive means.

3. In combination with an open rectangular truck body capable of containing liquid concrete, a track fastened along each side of the outside of the body and extending substantially from one end thereof to the other, rollers supported on the respective tracks, upright members in the truck body and located close to the sides thereof, said upright members being supported spasms 7.: from the rollers, a plurality of narrow stirring bars disposed horizontally inside the body and spaced one above the other, with the top bar considerably below the top edge of the truck body and the bottom bar close to the bottom of the inside of the body, said bars being fastened to the uprights, power means for moving the rollers, uprights and bars back and forth along the tracks, and driving means connecting the same with the power means. 7

' ERNESTO D. ALESSIO.

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

Number STATES PATENTS Name Date Prochnow Mar. 18, 1884 Garvey Oct. 21, 1890 Has'sam Feb. '9, 1909 Lockwood Sept; 6, I932 Shorter Jan. 17, 1933 Morrow Feb. 21, 1933 Coulboum Sept. 18; 1934 Feltault Nov. 12, 1935 Sinks Dec. 17, 1935

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