Waste concrete container

A waste container for the disposition of waste concrete comprising a bottom floor section having a major dimension extending longitudinally of the container, front and rear lateral dimensions which are substantially less than the major longitudinal dimension, and a forward end closed by a forward transverse wall section. Opposed side walls extend longitudinally of the container and upwardly from the bottom floor section to define with the bottom floor section a receptacle for waste concrete. The side walls are flared from the front to the back of the container to provide a back opening which has a lateral dimension greater than the lateral dimension of the forward transverse wall section. The side walls are sufficiently flexible to permit relative displacement between a first lateral dimension corresponding to the configuration of the side walls when they are not stressed and a second lateral dimension which is less than the first lateral dimension. A reconfiguration system is connected to at least one of the side walls and effective to compress the lateral dimension of the side walls relative to one another from a first somewhat greater lateral dimension to the second reduced lateral dimension when a plastic mass, such as unset concrete or the like, is added to the container.

BACKGROUND OF THE INVENTION
 In the construction industry it is a common practice in pouring large
 quantities of concrete to use concrete trucks ranging in capacity from 10
 cubic yards to about 12 cubic yards to transport the plastic hydraulic
 concrete mix from a batching plant to the construction site. The timing
 and dispatching of concrete trucks is very important since the age of the
 concrete in the truck is significant. For example, a typical specification
 for concrete for a construction project may require that the concrete be
 "fresh" or "plastic" for as long as about one-half hour to two hours after
 batching to arrive at the construction site in a plastic concrete
 condition. If the concrete in a given truck is not sufficiently fresh to
 meet specifications, the concrete must be disposed of in some fashion. In
 many cases, the truck will be simply driven back to the batching plant and
 the concrete poured onto the ground where it is allowed to set and then
 broken up and ultimately hauled away to a landfill or other disposal site.
 Alternatively, the concrete truck may dispatch its load of concrete at
 some other location since it is obviously critical that the concrete not
 be allowed to set up in the interior of the concrete truck.
 Even where the concrete is in spec in terms of its age, the truck, after
 dispensing its load, will contain some residual concrete which, even
 though it may amount to only a few cubic feet, must be removed from the
 drum of the truck prior to reusing the truck. Typically, the concrete is
 removed from the truck by washing out the interior of the drum with water.
 The water, as it exits the drum, carries with it the residual concrete.
 This concrete may be discarded, or in some cases, the water concrete mix
 can be passed to a reclaiming system where aggregates and perhaps water
 are reclaimed for further use. Alternatively, the residual concrete can be
 simply poured out on the ground at a suitable location at the batching
 plant for ultimate disposal.
 The concrete, once it is allowed to harden, can, as noted above, be broken
 up and then hauled away in trucks such as dump trucks, trailer trucks, and
 the like. The containers for these trucks are variously configured to deal
 with loose materials, such as gravel, stone, and the like. For example,
 U.S. Pat. No. 5,460,431 to McWilliams discloses a dump truck which can be
 used to unload particulate loose materials including materials such as wet
 sand and clays or the like which tend to become clogged in the trailer or
 that may have a tendency to become stuck and thus difficult to dump from
 the trailer at the disposal location. In the McWilliams patent the
 container for the dumping material is characterized as being
 "double-tapered" to facilitate dislodgement of the contents from the
 trailer. The double taper is provided by a tapered bottom floor that is
 wider at the back than at the front of the dump truck and also tapered
 upwardly in the side wall configuration so that the side walls slope
 upwardly and outwardly and are taller near the front end of the container
 than at the rear end. The cross-sectional area of the trailer defines a
 equilateral trapezoid which has a vertical height somewhat greater than
 the transverse dimension of the bottom floor section and with the side
 walls flared upwardly at an obtuse angle of about 111.degree. to
 112.degree. to provide a substantially larger horizontal upper dimension.
 Another dump truck body, which is configured with a rearwardly-flared
 container and with the side walls curved upwardly and outwardly, is
 disclosed in U.S. Pat. No. 1,989,125 to Atwell. The side walls of the
 truck are curved to provide a very rigid configuration. Yet, other truck
 bodies which are rearwardly tapered or otherwise configured to facilitate
 the removal of materials, such as gravel, clay, or wet earth, by dumping
 are disclosed in U.S. Pat. No. 1,627,336 to Nelson and U.S. Pat. No.
 5,090,773 to Guillaume.
 SUMMARY OF THE INVENTION
 In accordance with the present invention, there is provided a waste
 container of the type to be employed with a transfer system for the
 disposition of waste concrete. The container comprises a bottom floor
 section having a major dimension extending longitudinally of the container
 and front and rear lateral dimensions which are substantially less than
 the major longitudinal dimension. The container is closed at its forward
 end by a forward transverse wall section. The container further comprises
 opposed side walls extending longitudinally of the container and upwardly
 from the bottom floor section to define with the bottom floor section a
 receptacle for waste concrete. The longitudinal side walls are flared from
 the front to the back of the container to provide a back opening which has
 a lateral dimension greater than the lateral dimension of the forward
 transverse wall section.
 The side walls are sufficiently flexible to permit relative displacement
 between a first lateral dimension corresponding to the configuration of
 the side walls when they are not stressed and a second lateral dimension
 which is less than the first lateral dimension. The container
 configuration further comprises a reconfiguration system connected to at
 least one of the side walls. The reconfiguration system is effective to
 compress the lateral dimension of the side walls relative to one another
 from the first somewhat greater lateral dimension to the second reduced
 lateral dimension when a plastic mass, such as unset concrete or the like,
 is added to the container. Preferably, the reconfiguration system
 comprises an adjustable tension member connected at its end to the side
 walls at a location intermediate of the forward and back portions of the
 container. The bottom floor section of the container is substantially
 monoplanar to provide a flat surface upon which the waste plastic concrete
 can spread or be spread as it is poured into the container. Preferably, a
 major vertical dimension of the side wall section is substantially
 monoplanar and is oriented relative to the bottom floor section in an
 approximately perpendicular relationship.
 In a further aspect of the invention, there is provided a method for the
 disposition of waste concrete employing a longitudinally-extending
 container having a bottom floor section and longitudinal side walls
 extending upwardly from the bottom floor section which are flared from the
 front to the back of the container. The side walls of the container are
 drawn toward one another before or concomitantly with the addition of a
 mass of plastic concrete to the interior of the container. By compressing
 the side walls inwardly toward one another, the plastic concrete is
 allowed to set with the side walls in the compressed inward relationship.
 After the concrete has at least partially hardened to become
 self-supporting, the side walls are removed from the compressed
 relationship to an extended relationship in which the side walls move
 outwardly from one another to provide a clearance space between the
 hardened mass of concrete and the side walls. The hardened mass of
 concrete is then withdrawn from the container through the back portion
 thereof.
 In yet a further embodiment of the invention, there is provided a method
 for the distribution of waste concrete at a terminal station, such as a
 concrete batching plant, from which concrete trucks are dispatched and
 returned. A transfer system, including an elongated container with a
 bottom floor section and flared side walls, is located at the terminal
 station. The side walls of the container are compressed inwardly toward
 one another at an intermediate location between the front and rear of the
 container, and a mass of plastic concrete from a concrete truck arriving
 at the terminal station is dispensed from the truck into the container.
 The concrete so dispensed may constitute a residual concrete content which
 may range from several cubic feet to as much as a cubic yard or more of
 concrete. This procedure is repeated a plurality of times with residual
 concrete removed from concrete trucks as they arrive at the terminal
 station. Once the container is filled to the desired capacity, it is then
 transported to a desired location for the disposition of waste concrete in
 the container. After the concrete has at least partially hardened to
 become self-supporting, the side walls are removed from the compressed
 relationship to the extended relationship to provide a desired clearance
 between the mass of concrete and the side walls. The hardened mass of
 concrete can then be withdrawn from the back portion of the container.

DETAILED DESCRIPTION OF THE INVENTION
 As noted previously, it is a conventional practice to configure the
 container beds of dump trucks and the like in a manner to facilitate
 removal of loose materials from their interior. The present invention
 proceeds in a manner contrary to the conventional prior art practice by
 providing a container for a dump truck, such as a "roll-off" truck or the
 like, which is configured to facilitate the disposal of concrete as a
 large solid mass. Thus, rather than disposing of the plastic concrete by
 pouring it on the ground and then breaking it into particulate form, the
 concrete is poured into a transferable container and allowed to set in a
 unitary mass which is transported to a suitable disposal site. The
 container is configured to provide a long bed which is relatively flat in
 cross section to facilitate transfer of the concrete in a mass having a
 relatively low center of gravity. In addition, the concrete will harden in
 a cross-sectional configuration which facilitates hardening throughout the
 mass of concrete so that it can be ultimately removed from the container
 body as a large mass or broken up in perhaps two or three large chunks of
 concrete.
 As noted previously, it is often necessary to dispose of concrete which is
 contained in the familiar concrete trucks with their rotating drums. One
 situation calling for concrete disposal is the somewhat unusual situation
 of a concrete truck containing concrete which has been allowed to age so
 that it is not within specifications and cannot be used in construction
 projects for which it was initially intended. Another more common
 situation is in the cleaning of concrete trucks as they return from an
 assigned trip containing residual amounts of concrete. Typically, the
 rotating drum upon arriving at a batching plant or some other terminal
 location will be cleaned out by running water through the truck as the
 drum is rotated and flushing the residual concrete from the truck. The
 truck can then be refilled with a fresh batch of concrete.
 Several practices are followed in flushing concrete trucks to remove
 residual concrete. In some cases, the concrete is simply dumped on the
 ground and either left at the cleaning location or the concrete ultimately
 broken and hauled away to a landfill or other waste disposal site. In some
 instances, steps are taken to flush the concrete, now containing
 substantial amounts of water, into a recovery system from which aggregates
 and water can be recovered and reused in batching plant operations.
 The present invention proceeds in a manner contrary to the normal prior art
 practice and provides for the use of a transferable container, e.g. on a
 roll-off truckbed, as described previously, which can be used as a
 depository for the concrete flushed from concrete trucks returning from an
 assigned trip. The container is configured in a manner so that residual
 concrete can be flushed from the returning trucks and dispensed from the
 truck drums into the interior of the container. Typically, as many as 20
 or more trucks can be cleaned and flushed into the container before the
 container is full. During this time, the sides of the container are
 compressed laterally in a manner to provide an ultimate clearance between
 the hardened concrete and the container side walls so that when the
 roll-off truck or other system containing the container is sent to a
 disposal location, the hardened concrete can be easily removed from the
 container.
 While the most common transfer system for the container containing the
 accumulated concrete will take the form of a vehicle, such as a roll-off
 truck or a trailer truck equipped with a dumping mechanism, the present
 invention can be carried out using other transfer systems, such as rail
 cars which can carry the container and be configured for disposal of
 concrete from the container. However, the invention will be described with
 reference to a roll-off truck modified to incorporate a waste concrete
 container configured in accordance with the present invention.
 Turning now to FIG. 1, there is illustrated a side elevation of a roll-off
 truck comprising a truck chassis 10 having wheels 12 and equipped with a
 forward cab 14. The chassis 10 is equipped to support an elongated
 container 16, as described in greater detail later and a lifting mechanism
 18, such as a hydraulic hoist incorporating a hydraulic piston mechanism
 coupled between the chassis and a bridle section 19 of the container 16.
 Lifting mechanism 18 may be of any suitable type. Such mechanisms, which
 can be employed in the present invention, are disclosed in U.S. Pat. Nos.
 4,934,898 to Galbraith and 5,601,393 to Walschmidt, the entire disclosures
 of which are incorporated herein by reference. The container is mounted on
 a frame 17 which is adapted to pivot at the back end of the truck chassis
 10 and is provided with rollers 20 at its back section so that when the
 container is elevated, the rollers will rest on the ground. The container
 16 is also provided with a ratchet system 22, to be described in detail
 later which functions to compress the side walls of the container as the
 container is filled with plastic concrete.
 The roll-off truck lifting mechanism is configured to tilt the front end of
 the container upwardly through a significant angle, preferably an angle of
 at least 45 degrees from the horizon, in order to facilitate removal of
 hardened concrete from the container in a manner described below. Thus, as
 illustrated in FIG. 2, the container 16 can be elevated through the
 lifting mechanism comprising a pair of hydraulic cylinders 24 (only one
 being shown in FIG. 2) which extend from the lifting mechanism base on the
 chassis up to the bridle section 19 of the container.
 Turning now to FIG. 3, there is illustrated a plane view of the container
 16. The container comprises an elongated, longitudinally-extending bottom
 floor section 24 and opposed side walls 26 and 27. The side walls extend
 from an upwardly sloping front transverse wall section 28 at the forward
 end of the container to the rear of the container which is closed by a
 removable rear gate 30. Rear gate 30 is connected to the container on the
 passenger side of the truck by a hinged connection 32. The side walls 26
 and 27 are flared outwardly slightly from the front to the back of the
 container to facilitate removal of a concrete mass from the container in a
 manner to be described later. In an embodiment of the invention
 constructed to carry approximately 10 cubic yards of concrete, the length
 of the container, indicated by dimension d3 in FIG. 3, is approximately 23
 feet long. The side walls are flared from front to back from a front
 internal width, indicated by dimension d1, of 831/2 inches and a rear
 internal width, indicated by dimension d2, of 863/4 inches. This provides
 a composite angle of flare of the side wall sections of about 0.9.degree..
 By the term composite angle of flare, as used herein, is meant the sum of
 deviation of the two side walls from the perpendicular, as indicated by a
 right angle formed between the longitudinal dimension of the container and
 the transverse dimension of the container. Thus, in the embodiment
 illustrated in FIG. 3, each of the side walls 26and 27 is flared outwardly
 by an angle of about 0.45.degree. corresponding to an obtuse angle made by
 the side wall and front wall section of 90.45.degree., as indicated by
 angle a1 in FIG. 3. While it is preferred that both side walls be flared
 outwardly, it is to be recognized that the composite angle of flare can be
 provided with one side wall forming a 90.degree. angle with the front wall
 and the other side wall being flared outwardly at about 0.90.degree.
 (corresponding to an obtuse angle of 90.9.degree., again producing a
 composite angle of flare of 0.9.degree..
 The composite angle of flare for the container is significant. An angle
 which is too small will provide insufficient clearance between the side
 walls and the hardened mass of concrete, thus making removal of the
 concrete under the influence of gravity difficult. However, if the angle
 is too great, the set concrete block will tend to shift in some instances
 under the influence of gravity, thus becoming more or less wedged within
 the container so that it could not be readily discharged by gravity.
 Preferably, in carrying out the invention, the composite angle of flare
 for the side walls in within the range of 0.8-1.2.degree. and, more
 particularly, within the range of 0.9-1.1.degree.. In experimental work
 carried out with respect to the invention, a composite angle of flare of
 about 1.5.degree. (each of the side walls flared at an angle of
 0.75.degree.) was shown to allow some shifting, which was deleterious to
 removal of the concrete block under the influence of gravity. As indicated
 previously, a composite angle of flare of 0.9.degree. has been found to
 work satisfactorily for a container adapted to contain about 10-11 cubic
 yards of concrete.
 An important feature of the present invention is the use of side walls
 which are sufficiently flexible to permit compression through the use of a
 suitable reconfiguration system so that they can be compressed during the
 time the plastic concrete is loaded into the truck and allowed to set.
 Suitable side walls for the embodiment illustrated in FIG. 3 can take the
 form of 3/16-inch thick steel having two tubular side channels, an upper
 side channel 34, and an intermediate side channel 36 (not shown in FIG. 3)
 to provide sufficient longitudinal strength to prevent buckling by the
 hydrostatic head imposed by a plastic mass of concrete within the truck.
 Another important feature of the invention is a reconfiguration system
 adapted to compress the lateral distance between the walls at an
 intermediate location of the container. In the embodiment illustrated in
 FIG. 3, the reconfiguration system comprises a tension bar 40 equipped
 with a ratchet mechanism 42. The tension bar 40 is connected to upstanding
 lugs 44 and 45 which extend upwardly from the side walls 26 and 27. The
 ratchet section includes a handle 43 which can be moved from the
 horizontal position shown in FIG. 3 to a vertical position and actuated to
 draw the two side walls inwardly so that they are compressed by about 1/2
 to 11/2 inches to a reduced lateral dimension at the intermediate section
 of the container. Stated otherwise, the side walls are retracted inwardly
 by about 1/2 to 2% of the width of the container.
 FIG. 4 is a side elevational view (from the driver's side of the truck) of
 the container shown in FIG. 3. In FIG. 4, the ratchet handle 43 is
 oriented to the vertical position for actuation to compress the side walls
 toward one another. As noted previously, the rear gate 30 is hinged to the
 side wall 26 on the passenger side of the truck. The driver's side of the
 truck is provided with a latching mechanism 48 which can be used to secure
 the tailgate in the closed position. The tailgate includes forwardly
 extending arms 30a and 30b which are secured to the suitable locking lugs
 on the side wall when the tailgate is the closed position. In the open
 position, the tailgate can be rotated through an angle of about
 270.degree. so that it lies flush with the side wall 26.
 Additional details of the container are illustrated in FIGS. 5 and 6 which
 show front and rear elevational views of the container of FIG. 3. FIG. 5
 shows the structure of the front bridle section which extends forwardly
 and upwardly from the bottom frame 17 which supports the floor of the
 container. The bridle section is adapted to receive the lifting means,
 such as the hydraulic pistons shown in FIG. 2. The rear gate, as
 illustrated in FIG. 6, includes hinges 32 on the right side connected to
 the wall section and on the left side the forwardly-extending lugs 30a and
 30b shown also in FIG. 4.
 FIG. 7 is a schematic cross-sectional view of the container shown in FIG. 3
 illustrating the important dimensional configurations of the container.
 Although, as described later, the side walls can be flared outwardly from
 top to bottom as viewed in cross section, preferably they are
 substantially vertical, with the exception of miter joints 26a and 27a
 indicated in FIG. 7. The miter joints are provided at the intersection of
 the wall sections with the floor section. As indicated in FIG. 7, the
 bottom floor is substantially monoplanar to provide a flat surface upon
 which to support the hardened concrete. In addition, the cross-sectional
 configuration of the container is a rectangle of a relatively small
 vertical dimension, which at the most is no more than the average lateral
 dimension and preferably is much smaller. Specifically, the average height
 of the side wall section is no more than one-third of the average lateral
 dimension of the bottom floor and preferably within the range of 0.2 to
 0.3 of the average lateral dimension of the flat bottom floor section.
 Also, as shown, for example, in FIG. 7, the side wall sections are
 monoplanar and intersect the bottom wall section in a substantially
 perpendicular relationship. While a slight outward flare can be
 accommodated, this should not exceed more than a few degrees. The angle
 between the bottom section and the side walls should be either
 perpendicular, i.e. 90.degree., or only slightly obtuse, that is, an
 obtuse angle up to about 95.degree.. It is highly desirable that a
 substantial upward flare be avoided in order that the operation of the
 compression system effect a substantial vertical portion of the side
 walls.
 The relatively shallow bed of the container employed in the present
 invention is particularly advantageous in the application of the invention
 in which the container system is used as a depository for residual
 concrete cleaned out of trucks returning from runs from a batching plant.
 The repeated dispensing of residual concrete from a plurality of trucks
 results in the waste concrete being added to the container in lifts which
 typically may range from a fraction of an inch to several inches in
 thickness. The lifts may be deposited at close intervals, or they may be
 deposited at intervals of several hours between the cleaning of one truck
 and the cleaning of the next truck, depending upon the schedule of
 deliveries. In either case, the side walls can be maintained in the
 compressed configuration by the ratchet system until the container is
 filled to capacity. The waste concrete truck is then dispensed to a
 suitable disposal site while retaining the side walls in the compressed
 configuration as necessary while the concrete continues to harden in
 transit. After the concrete in the container has hardened and has become
 self-supporting, whether at the batching plant, in transit, or after
 reaching the disposal site, the ratchet system can then be released to
 allow the side walls to return to their original configuration. The front
 end of the container is then elevated, preferably through an angle of at
 least 45.degree., after opening of the tailgate 30. After the container
 has reached the elevated position, as shown in FIG. 2, the truck is driven
 forward slightly to allow the concrete to be dispensed under the influence
 of gravity, usually in several large chunks. That is, the concrete mass
 may split laterally at one or two, or perhaps three, locations along the
 longitudinal length of the hardened mass of waste concrete.
 As can be recognized from the foregoing description, the relatively shallow
 rectangular configuration of the container is advantageous in several
 respects. It provides a relatively low center of gravity enabling the
 waste concrete to be transported easily and safely. The plastic concrete,
 as it is poured into the container in several discreet lifts, ranging
 perhaps 1/2-inch to several inches in thickness will tend to harden in a
 cohesive mass which can be removed from the waste concrete track with
 relative ease.
 While the preferred cross-sectional configuration of the waste concrete
 container embodying the present invention is rectangular as shown in FIG.
 7, it is also possible to provide a container having a configuration in
 which the side walls taper upwardly and outwardly to provide a trapezoidal
 configuration. This is illustrated in FIG. 8, which is a schematic
 cross-sectional view of a container 50 having a flat bottom portion 52 and
 opposed side walls 54 and 55 which extend upwardly to an upper rim having
 longitudinally-extending support beams 57and 58. In this embodiment of the
 invention, the vertical dimension of the container should be relatively
 shallow as before, typically providing a ratio of the width of the floor
 to the height of the trapezoid of about 4:1. Where the sides are flared
 outwardly, they should, nevertheless, remain substantially close to the
 vertical and should form an obtuse angle with the floor section, as
 indicated by angle a2 of FIG. 8 of no more than about 115.degree. and
 preferably no more than 95.degree. as indicated previously. A container of
 this configuration can be operated to compress its side walls to expedite
 the formation of a clearance space once the concrete mass has hardened.
 However, the concrete mass is not dislodged from the container as
 effectively as it is in the preferred embodiment, as characterized by the
 rectangular cross section of FIG. 7.
 Although not necessary, it will usually be desirable to coat the interior
 surfaces of the container, particularly the floor section and the side
 walls with an oliophilic release agent in order to avoid a tight bond
 between the concrete as it sets up and the surrounding container surfaces.
 A suitable release agent for use in this regard is a petroleum fraction,
 such as diesel oil, or synthetic commercial release agents including
 minerals oils and vegetable oils.
 Having described specific embodiments of the invention, it will be
 understood that modifications thereof may be suggested to those skilled in
 the art, and it is intended to cover all such modifications as fall within
 the scope of the appended claims.