Concrete mixing plant

Abstract

A concrete mixing plant for automatically mixing predetermined amounts of wet concrete comprises a plurality of component bins having metered outlets for depositing prescribed amounts of individual concrete components onto a common conveyor belt moving at a relatively fast speed. The acceleration of the material along the belt is utilized to initially mix the components and to move the components in layers to a discharge end. The components are propelled from the discharge end against an upright abutment surface. The moving impact of the components with the surface is sufficient to mix the components into homogeneous concrete. The mixed concrete is then moved from the abutment surface to a dispensing station.

Description

BACKGROUND OF THE INVENTION

The apparatus of the present invention relates generally to concrete mixing plants and more specifically to such plants utilized to automatically and continuously mix separate concrete components into a wide range of predetermined quantities or batches.

Conventional concrete plants and mixer trucks that can normally only be utilized for mixing single large batches of concrete. Such apparatus often are preset to mix a batch that is too large for a specific job. The remaining concrete must either be dmped or resold. If the remaining concrete is to be resold, it often must be watered down before it reaches the second job site.

Conventional truck-mounted mixers are necessarily large in volume, to accommodate the labor cost of the individual driver. Furthermore, the concrete must be used within a fixed time span from its receipt in the truck. Delays in transit or unforeseen delay at the site of usage make it difficult to maintain a constant delivery schedule. Usually excess trucks and drivers must be used to assure a ready supply of concrete.

Much greater control of concrete consistency and cost is possible by on-site mixing. However, conventional concrete mixers are designed for large scale batch mixing. The mixer described below fills the need for an on-site mixer readily adjustable to meet the instant demands of the user as to quantity and quality.

A further problem is that with a premixed batch, it is difficult or impossible to make last minute adjustments in mixture proportions. This difficulty arises frequently in areas where quick climate changes are common and further, where specific building construction techniques call for different concrete stress characteristics.

These problems are realized to a limited degree by the apparatus disclosed in U.S. Pat. Nos. 3,339,898 and 3,469,824 granted to Futty et al. These patents disclosed mixing methods and mixing truck constructions wherein concrete components are supplied to an elongated trough. An elongated shaft is provided within the trough having a plurality of spatially disposed mixing paddles and helical feeding screws. Rotation of the shaft simultaneously mixes the particulate ingredients and moves them toward an output end.

U.S. Pat. No. 3,310,293 granted to Zimmerman discloses a concrete mixing and delivery system wherein concrete components are held within a plurality of bins supported on a truck frame. The components are held separately within the bins that provide means for dispensing predetermined amounts of the components onto an elongated conveyor belt. The conveyor delivers the separate components to an external mixing trough where water is applied to the dry components and they are mixed by an elongated auger within the mixing trough.

Another patent granted to Futty, U.S. Pat. No. 3,336,011, discloses a system and means for selectively mixing concrete and incorporating additives therein which, like the Zimmerman apparatus, deposits concrete components onto a conveyor and delivers them separately to a mixing trough. Water is added to the components at the mixing trough as an auger is rotated to mix the components together. The principal feature of this invention is the provision of separate water supply systems in which either pure water or an antifreeze solution may be selectively applied to the mixture.

A further patent granted to Futty, U.S. Pat. No. 3,623,708 discloses a system and means for selectively mixing concrete and incorporating dry additives therein. The apparatus includes means for delivering dry additives to the concrete batch and incorporates a hopper assembly for holding the dry additives. The hopper contains agitator means for mixing and breaking up the dry additive ingredients. A controlled feed means selectively controls the amount of dry additives passed from the hopper into an enclosed auger arrangement. The additives are conveyed by the auger arrangement into an auxiliary mixing trough where they are incorporated into a concrete batch.

U.S. Pat. No. 2,976,025 granted to G. M. Pro discloses a combined mixer and conveyor for concrete components. Individual hoppers are used in the Pro apparatus for storing each concrete component. The apparatus includes means for delivering sand and cement to a helical conveyor within a trough. The materials are received within the trough and tumbled and agitated as they are moved upwardly.

Another U.S. Pat. No. 2,946,597, granted to M. W. Simonsen, discloses a fertilizer mixer and spreader with a partition container wherein fertilizer components are kept separately in longitudinally spaced bins. The bins include bottom openings through which the individual components are placed onto a conveyor and delivered to a fertilizer dispensing impeller. The fertilizer dropped onto the impeller is spread across the ground behind the supporting vehicle.

U.S. Pat. No. 796,591 granted to W. B. Martin describes a concrete mixer in which individual concrete components are contained within separate hoppers. The apparatus includes means for removing measured amounts of gravel, stone, cement and sand in predetermined quantities and dropping them gravitationally downwardly into a mixing auger.

It may be noted that each of the above-cited patents relating to an apparatus for mixing separate concrete components utilizes an auger or paddled wheel arrangement as means for mixing the components together. The apparatus of the present invention differs from this art in that the mixing of the components is accomplished by impact and shearing action. Mixing by impact is accomplished as the components are propelled against a stationary abutment surface, while mixing by shearing layers or strata of the components is affected as the components are delivered from storage bins or fall from the abutment surface onto to second conveyor belt or other receiving conveyor.

SUMMARY OF THE INVENTION

A concrete mixing plant is described comprising conveyor means for carrying concrete component materials along a first direction of travel to a discharge point where they are propelled against an upright abutment surface. Supply means is also provided for placing controlled quantities of concrete component materials onto an upwardly facing surface of the conveyor means.

It is a first object of my invention to provide a concrete mixing plant that is capable of producing a continuous supply of consistent wet concrete.

Another object is to provide such a plant that may be controlled while in operation, to change mixture proportions and the consistency of the concrete produced.

It is an additional object of my invention to provide such a concrete mixing plant that is relatively simple in construction and therefore easy to operate. It can be transported to the job site or used as a central mixing plant.

A yet further object is to provide such a mixing plant that includes separate storage bins for each individual concrete component with a metering and discharge mechanism attached to each bin to facilitate control of the quantity of each individual component supplied to the mixture.

These and further objects and advantages will become apparent upon reading the following disclosure which, taken with the accompanying drawings, discloses two preferred forms of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial view of a first embodiment of the mixing plant;

FIG. 2 is an enlarged elevational section view taken substantially along line 2--2 in FIG. 1;

FIG. 3 is an enlarged elevational section view taken substantially along line 3--3 in FIG. 1;

FIG. 4 is an enlarged elevational section view taken substantially along line 4--4 in FIG. 1;

FIG. 5 is a fragmentary operational view taken substantially along line 5--5 in FIG. 1;

FIG. 6 is a section view illustrating a weighing mechanism utilized in conjunction with the present invention;

FIG. 7 is a plan view of a slurry mixing mechanism incorporated in the present invention;

FIG. 8 is a cross sectional view taken substantially along line 8--8 in FIG. 7;

FIG. 9 is a plan view of a mixing plant mounted to a truck frame;

FIG. 10 is an elevational view of the plant and truck as shown in FIG. 9;

FIG. 11 is a sectioned view taken along line 11--11 in FIG. 9; and

FIG. 12 is a fragmentary sectioned view taken along lines 12--12 in FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of the concrete mixing plant invention is illustrated in FIGS. 1 through 8 of the attached drawings and is generally designated therein by the reference numeral 10. A mixing plant 10 as shown, is supported by a framework 11. A plurality of component bins 12 and a dry cement bin 12a are located on the framework for receiving and storing individual concrete components such as sand, various size aggregate and, of course, dry cement.

The component bins are elements of a supply means whereby the individual concrete components are placed in controlled layered quantities on an upwardly facing surface 13 of first and second conveyor means 14 and 26 respectively. In operation, the supply means is utilized to deliver idividual dry concrete components to the first conveyor means 14 which in turn initially moves the components along a first direction of travel to a discharge end 15. The dry components fall from discharge end 15 onto the second conveyor means 26. A wet cement slurry is added to the components as they move along on the second conveyor means 26 to a second discharge end 33. The components leave the discharge end 33 as a concrete mixture.

The first conveyor means 14 is powered by means of a motor 16 to move the upward-facing surface 13 at a relatively high linear speed sufficient to propel the components outward from the discharge end 15 and against a first abutment surface 17. The abutment surface 17 is held stationary relative to the material moving on conveyor means 14.

The component material is propelled from the discharge end 15 and impacted against a concave-shaped surface 21 on abutment 17. Surface 21 is positioned adjacent discharge end 15 to face the oncoming concrete components. The concave surface 21 deflects the component material downwardly while simultaneously "focusing" the material somewhat toward a center point of the surface 21. The component layers are thereby blended together as they fall gravitationally from abutment 17.

The concrete components fall from abutment surface 17 onto the working surface 25 of a second conveyor means 26. As may be noted in FIG. 1 and 5, the working flight of conveyor means 26 is angularly positioned relative to the upwardly facing surface 13 of conveyor means 14 so that the path of movement of the concrete components is abruptly changed upon reaching the working surface 25. This change in direction shears the vertical layer arrangement of components and effectively mixes them into a continuous mixed stream.

The second conveyor means 26 is mounted on framework 11 and leads past an upright cement bin 12a. Dry cement is supplied from the cement bin 12a to a slurry mixer 30 that combines the cement with water to form a slurry. The slurry is then deposited onto the working surface 25 and is mixed with the blended components thereon.

The second conveyor means 26 is powered by means of a motor 32 to move the working surface 25 at a linear velocity substantially faster than the velocity of the upwardly facing surface 13 of the first conveyor means 14. By providing such increased speed in combination with the angular relationship between the first and second conveyor means 14 and 26 respectively, an additional mixing function is performed as the components and slurry are deposited onto the working surface 25. This mixing action may be described as a shearing action wherein layers primarily comprising the blended components on one level and the slurry on another are thoroughly tumbled and rolled together due to the abrupt acceleration of the components as they engage the rapidly moving surface 25.

The second conveyor means 26 moves the mixed concrete along a second path of travel to a discharge end 33. A second abutment surface 34 is held stationary outward from the discharge end 33 so that the concrete propelled from the discharge end 33 will strike a second concave surface 36 and be deflected before falling to a receptacle below (not shown). The purpose of the second abutment surface 34 is to insure that the concrete is finally delivered as a consistent mixture.

Referring now in greater detail to the supply means, attention is directed to FIGS. 4 and 6. Each component bin 12 and cement bin 12a includes a metered outlet 40. Outlets 40 are controlled to continuously deliver prescribed amounts of component material, in terms of units of weight per foot, along continuous weighting conveyors 41. As illustrated in FIG. 6, the weighing conveyors 41 are supplied with a weight sensing transducer 42. Transducer 42 is a component of the gate control means associated with each component and cement bin 12, 12a for monitoring the amount of the components and cement to be mixed together to form a concrete mixture.

The gate control means utilizes a weight sensing transducer for each bin 12, 12a to provide a signal that operates a cylinder 45 to open or close a metering gate 46. The metering gates 46 are positioned directly adjacent to the lower discharge openings 47 of component bins 12, 12a. The gates 46 may be raised or lowered in response to the weighing transducers to continuously flow from the bins onto the working flights 52 of weighing conveyors 41.

It may be noted from FIG. 1 that the weighing conveyors 41 are powered by a common motor 50 and drive shaft 51. Motor 50 and common drive shaft 51 insure that the working flights 52 are powered at identical linear speeds. This provision insures that a proper ratio of components by weight is delivered to the first conveyor means 14.

In the preferred embodiment described above, all "dry" components (sand, aggregate, cement) are controlled as to quantity by weight. Such controls pre-suppose a known water content for the sand and aggregate, which must be known for final concrete composition. While weight monitoring is most versatile and is adaptable to components of any water content, volumetric monitoring of components can be used where the sand and aggregate are water-saturated or provided at a constant water content such that their water component can be overlooked in calculating mixer requirements.

A shut off gate 55 is provided on each bin 12, 12a. The gates 55 are powered by cylinders 66 to cut off the supply of material to the bin discharge openings. This provision enables independent operation of metering gates 46 so that they need not be reset for purposes other than controlling the component mixture ratios.

The slurry mixer 30 of the supply means is best illustrated in FIGS. 7 and 8. Slurry mixer 30 is positioned on framework 11 adjacent the metered outlet 40 of the weighing conveyor 41 associated with cement bin 12a. Slurry mixer 30 includes a partially enclosed housing 60 having an upwardly facing inlet 61 for receiving measured amounts of cement from bin 12a. Cement entering the slurry mixer 30 first falls gravitationally onto an upright cone 63. Cone 63 is continuously powered by a motor 64 to rotate about the axis of an upright shaft 65. The cement introduced at the top of cone 63 hits the moving surfaces and slides down the inclined sides of cone 63 where it is engaged and propelled radially outward by protruding paddles 69 mounted to the cone 63.

Water is supplied to the slurry mixer by a metered supply pipe 70. The metered water is directed through supply pipe 70 to a circular spray tube 71 within housing 60. Spray tube 71 includes a plurality of discharge holes 72 for directing the water onto the cement powder sliding down the inclined sides of cone 63. The water quickly combines with the cement to form a slurry mixture, which is propelled radially outward from the housing 60 through tangential discharge ducts 75. Paddles 69 and the scroll housing combine to produce a centrifugal pump for the mixed slurry. A pair of delivery tubes 76 are connected to the discharge ducts and lead to discharge ends 80 directed toward the working surface 25 of second conveyor means 26, as illustrated in FIGS. 1 and 3.

One important feature of the slurry mixer 30 is its ability to mix relatively small amounts of slurry continuously and efficiently. It also facilitates selective control of the end condition of the concrete mixture by enabling individual control of the amounts of water and cement entering the housing 60.

The slurry mixer 30 assures even control of incoming material proportions and constantly mixes small amounts of cement and water to assure production of homogeneous slurry. This is impossible in a short duration when using conventional mixers. It includes no pumps which would require priming. It is self-emptying, as the cone 63 is constantly rotated and flow of material is dependent only upon control of incoming cement and water. In effect, slurry mixer 30 works "on demand", being always ready to supply mixed fresh slurry to surface 25 as needed. When slurry is not required, flow is temporarily halted by stopping the incoming flow of cement and water to mixer 30.

Where liquid additives are desired in the final concrete mixture, they are conveniently introduced in the water supply to pipe 70. Separate supply conduit and nozzles may be used when required.

In a typical slurry mixer having a cone of about 4 feet in diameter, cone 63 should be rotated at about 300 to 400 r.p.m. Typical belt speeds for the conveyors should be above 1,000 feet per minute for conveyor 14 and up to 2,000 feet per minute for conveyor 26. The final discharge conveyor for the mixed concrete can operate at about 500 feet per minute without appreciable separation of components.

Operation of the mixing plant may now be easily understood. Before or during initial operation, the metering gates 46 are set according to specific requirements for a desired concrete mix. The mixing procedure may then be initiated simply by activating motors 50, 16 and 32 to power the weighing conveyors 41 and the first and second conveyor means 14 and 26 respectively. Dry sand and aggregate components are delivered from the weighing conveyors 41 in layers or "ribbons" onto the upwardly facing surface 13 of first conveyor means 14. They tumble, roll and mix with one another as they are abruptly accelerated. The dry components are propelled from the discharge end 15 against the concave surface 21 of the first upright abutment surface 17. The deflection of the dry components from the concave surface serves to further blend the components together as they fall gravitationally onto the rapidly moving working surface 25 of the second conveyor means 26.

The linear speed of the working flight 25 and the abrupt angular directional change of the path of component travel facilitate further mixing of the components by shearing what remains of the component layers.

The wet cement slurry previously mixed by the slurry mixer 30 is then delivered onto the components to be tumbled and rolled along the surface 25, thoroughly mixing with the remaining components to form a concrete mixture before reaching the discharge end 33. The second abutment surface 34 insures a consistent mixture by again deflecting the moving stream of concrete as it is propelled from the discharge end 33 of the second conveyor means 26.

A slightly modified concrete plant incorporating this invention in a truck-mounted arrangement is shown in FIGS. 9 through 12 and is designated generally by the reference numeral 110. The mixing plant as shown is mounted to the framework 112 of a truck 111.

The mixing plant is comprised of a hopper 116 mounted to the framework 112 of the truck 111. The hopper is comprised of a series of bins defined by longitudinally spaced partitions 117 for the purpose of optimum weight distribution on the truck frame. The forward bin 121 is intended to store sand for the concrete mixture, a second or middle bin 122 is utilized to store cement, and a third or rear bin 123 is utilized to receive and store aggregate. As shown in FIG. 9, the bins are of relatively different size to accommodate proper proportions of the concrete components.

The bins include openings 124, 125 and 126 respectively in the bottom ends thereof. The openings are aligned above an elongated conveyor means 118 which serves to receive the concrete components from the individual bins and convey the components rearwardly to an abutment surface 119. The individual components are mixed as they strike the abutment surface. The abutment surface is utilized to mix the components into a relatively homogeneous concrete mixture. The mixture drops from the abutment surface onto a delivery means 120 which serves to direct the mixed concrete outward from the truck to be received and further transported by conventional concrete handling means.

The components held within the individual compartments are agitated by means of a plurality of fingers 127 mounted to rotatable shafts 128. The shaft 128 is powered by a drive motor 130 to continuously rotate the shafts and thereby agitate the components held within the bins.

The size of the openings 124, 125 and 126 are individually controlled by movable gates 135. The gates 135 each move within slides 136 formed in the bottoms of the bins. The gates are powered to slide across the openings by means of lever linkages 137 as shown in FIG. 10. Linkages 137 are actuated by cylinders 138 to selectively slide together or apart to control the amount of material flowing through the openings. Individual control of the gates facilitates adjustments in the ratio of components in the concrete mixture.

The components flowing gravitationally through the openings are received by a vane meter 140 which along with gates 135 define a control means for enabling selective control of component proportions. The meter 140 is comprised of a shaft 141 and a number of vanes extending along the shaft. The shaft is powered to rotate within a circular housing 143 by a drive shaft 144 from motor 130. By selectively rotating the shaft 141, measured amounts of each component may be received between the vanes, and deposited gravitationally onto the conveying means 118. The motor 130 may be controlled by a conventional switching means to facilitate selective rotation of the shaft to vary the amounts of concrete components deposited on the conveying means.

The conveying means is basically comprised of an elongated conveyor 145. Conveyor 145 includes an endless belt 146 having an upper working flight 147. As shown in FIG. 11, the cross-sectional configuration of the working flight 147 is concave. This configuration serves to hold the components near the longitudinal centerline of the belt. The belt 146 is powered by a drive motor 150 as shown in FIG. 10 to rotate about a circuit in the direction of the arrow shown in FIGS. 9 and 10. The conveyor extends from an idler roller 148 between the forward bin 121 and the cab of the truck readwardly under the bins 121, 122 and 123 to a discharge end 149 adjacent the rear end of the rearward bin 123. The working flight 147 of the belt is carried by a trough-shaped support 151 which serves to form the concave cross-sectional shape of the belt as described.

As shown in FIGS. 10 and 11, the support 151 includes independent weighing sections 152 spaced downstream from each bin 121, 122 and 123. The weighing stations may be utilized to indicate the proportions of the concrete components by weight.

Water is supplied to the concrete components from water supply tanks 153 which are mounted to the longitudinal sides of the bins 121, 122 and 123. Controlled amounts of water are provided to the concrete components through pipes or hoses 154 extending downwardly from the supply tanks 153. The pipes 154 extend longitudinally along the working flight of the conveyor 147 and include nozzles 156 which are directed toward the working flight 147. Water is added to the concrete components through the nozzles 156 as controlled by a valve 155 on each pipe 154.

It is conceivable that the water pipes and tanks could be eliminated and, in place of dry cement in the hopper 122, a wet slurry of cement could be produced in a suitable mixer and be selectively deposited on the working flight of the conveyor 145. With such an arrangement, the water tanks 153 could be used alternately as a water supply for production of the slurry and for cleaning purposes.

The primary feature of this embodiment of my invention is the operation of the conveyor 145 in relation to an abutment surface 119 positioned adjacent the discharge end 148. The working flight 147 is powered to move at a velocity of between 700 and 1000 feet per second. With such a velocity, it has been found that the components leaving the discharge end 149 of the conveyor will become substantially intermixed as they strike the abutment surface 119. The surface 119 is shown in FIG. 12 as a vertical wall. It may be noted however that such a surface may be provided by an upwardly moving flight of an upright conveyor belt whereby the individual components would be further intermixed as they strike the upwardly moving flight. In other instances, downward or transverse movement might be imparted to the conveyor flight.

The mixed concrete falls from the abutment surface 119 gravitationally into the delivery means 120 which is comprised of a series of mixing blades 160 mounted to a rotatable shaft 161. The mixing blades 160 are radially mounted to the shaft 161 to form a helix along the shaft axis and are powered to rotate about the shaft axis by a motor 164. The mixing blades 160 and shaft 161 extend longitudinally through the circular opening of a housing 162. The housing 162 extends to an open end or dispensing station 163. The concrete received from the abutment surface is moved along the housing by the blades 160 toward the dispensing station 163.

Housing 162 serves as a "surge" hopper for temporarily storing mixed concrete. The mixing blades 160 are therefore provided to maintain the concrete as a homegenous mixture within housing 162 until it is delivered from dispensing station 163.

Claims

What I claim is:

1. In a concrete mixing plant:

a framework;

supply means mounted on said framework for discharging quantities of individual concrete components at controlled delivery rates at individual outlets arranged along the framework in a straight path;

an endless belt conveyor mounted on said framework, said endless belt conveyor having an upwardly-facing surface arranged along said path beneath said outlet, whereby concrete components may be delivered from said outlets onto the upwardly facing surface of the conveyor, the upwardly facing surface being terminated at a discharge point at one end of the conveyor;

an upright abutment surface fixed to said framework and arranged along said path outwardly from said one end of the conveyor, said upright abutment surface having a width and elevation encompassing the width and elevation, respectively, of said upwardly facing surface;

and power means on said framework operatively connected to said conveyor for imparting velocity to said moving surface in a direction leading toward said one end of the conveyor at a rate such that mixing of the concrete components will occur on the conveyor and the concrete components will be propelled from said one end of the conveyor to impact the upright abutment surface.

2. The apparatus set out in claim 1 further comprising:

a second endless belt conveyor mounted on said framework and having an upwardly-facing surface arranged along a second path perpendicular to said first path, the upwardly facing surface of said second conveyor being elevationally located beneath said upright abutment surface to thereby receive the concrete components that impact the upright abutment surface.

3. In a concrete mixing plant:

conveyor means having an upwardly facing moving surface for carrying material in a first direction of travel along a path leading to a discharge point at one end of the conveyor means;

an upright abutment surface spaced outwardly from the discharge point of said conveyor means in said first direction of travel, said upright abutment surface having dimensions transversely and elevationally spanning the upwardly facing moving surface of said conveyor means;

supply means for placing controlled quantities of concrete component material onto said upwardly facing moving surface of said conveyor means;

power means operatively connected to said conveyor means for imparting motion to the upwardly facing moving surface of said conveyor means at a linear speed such that concrete component material on said surface is propelled from said surface at said discharge point in said first direction of travel and impacts said upright abutment surface;

an upwardly facing working conveyor surface located beneath said first upright abutment surface for receiving material that impacts said first upright abutment surface, said working surface being moved in a second direction of travel along a second path leading to a second discharge point at one end of said working conveyor surface;

a second upright abutment surface spaced outwardly from the second discharge point of said working conveyor surface in said second direction of travel, said second upright abutment surface spanning the working surface of said working conveyor surface both transversely and elevationally;

said power means being operatively connected to said working conveyor surface for moving said surface at a linear speed such that material is propelled from one end of said working conveyor surface in said second direction of travel and impacts said second upright abutment surface.

4. The apparatus set out in claim 3 wherein the second direction of travel is substantially perpendicular to said first direction of travel.

5. The apparatus set out in claim 3 further comprising:

cement slurry mixture means for placing controlled quantities of mixed cement and water onto the working conveyor surface.

6. The apparatus set out in claim 3 wherein said first and second abutment surfaces include concave impact surfaces facing said conveyor means for deflecting the components substantially toward a common focus.

7. In a concrete mixing plant:

a supporting framework;

an elongated hopper supported on the framework;

partitions dividing the hopper into individual bins for receiving concrete components;

an opening extending through the bottom of each compartment;

control means for selectively adjusting the flow of components through each compartment opening;

an upright abutment surface;

a powered endless conveyor belt positioned below the openings of the compartments for receiving concrete components therefrom;

said endless belt having its working flight extending longitudinally past the openings of the compartments to a discharge end longitudinally spaced from the openings;

said upright abutment surface being mounted to the framework and positioned adjacent the discharge end of such conveyor means in an attitude transverse to the path of the components on the conveyor belt;

power means on said framework operatively connected to said endless conveyor belt for moving the working flight thereof at a velocity such that components received on the belt are propelled against the abutment surface to thereby mix the components together; and

delivery means for receiving the mixed concrete from the abutment surface and moving it to a dispensing station.

8. The apparatus defined in claim 7 further comprising weigh stations supported on the frame beneath the working flight of the endless belt;

said weigh stations being longitudinally spaced along the belt with one positioned downstream of each bin and including means for weighing the individual components as they move along the conveyor means.