AU2001100117A4 - A mobile dry to wet concrete system - Google Patents

Description

1 A MOBILE DRY TO WET CONCRETE SYSTEM THIS INVENTION relates to a mobile dry to wet concrete system whereby the ingredients of concrete may be transported to a construction site and mixed together on-site.

In one aspect the invention resides in a vehicle having compartments holding separate the dry ingredients for concrete, a mixer downstream of the compartments for receiving the ingredients and mixing them together, characterised in that, the vehicle is of the non-tipping type and the relative quantities of ingredients are controlled to remain constant during a mixing cycle, the dry ingredients delivered to the mixer being controlled continuously by means of metering and conveying means automatically maintaining the relative relationship between the amounts of dry ingredients throughout a mixing cycle for practical consistency of the mix throughout the cycle. Preferably, water is also carried on the vehicle with the dry ingredients in a separate water compartment.

The ingredients for making concrete commonly involve cement powder, aggregate, fines and water. The aggregate, fines and cement powder are usually formed into a dry mix before the water is added. The aggregate is often stone, gravel, blue metal or any other material that may be used to form a solid mass once the mix has cured and may also embrace recyclable material including shredded rubber, woodchip and crushed glass etc.

Fines are used to form the matrix about the aggregate. Typical fines used are sand but may embrace any fine material suitable for the purpose including fine recycled glass and various mixtures of fines.

2 The aggregate and fines may be held separately in the vehicle or may be preblended and held together in a single compartment. Thus the vehicle may have a compartment for sand and a separate compartment for gravel or a single compartment holding pre-mixed sand and gravel.

The vehicle typically controls the ingredients delivered to the mixer by metering devices linked together so that any variation from a constant delivery rate of one ingredient is accompanied by an automatic adjustment of the delivery rate of the other ingredient so that the relative relationship between the ingredients remains, for practical purposes of concrete quality, effectively constant.

The metering devices used for the aggregate and fines or the aggregate-fines blend typically comprise augers to both metre and convey, the compartments having inclined side walls causing the auger to be fed at capacity at all times so that a predictable flow is available until the compartment is empty. The metering device for the cement powder is typically a gravity fed paddle wheel delivering a constant rate of cement powder as the paddle wheel rotates. The water is typically delivered at a rate determined by the rotation of the paddle wheel so that the correct amount of water is delivered relative to the cement powder which in turn is delivered in proper relative quantity with the sand and gravel.

Preferably, the metering devices for the dry ingredients are all linked mechanically by a common drive shaft.

The mixer may be attached to the vehicle. In this embodiment the mixer has a proximal end coupled to the vehicle and a distal end defining a discharge point, the mixer being coupled to the vehicle so that the discharge point may be moved relative to the vehicle. Alternatively, the mixer may be fixed relative to the vehicle having a discharge point into an inlet to a concrete pump, the concrete pump being of known type and being coupled to the vehicle adjacent the discharge point.

Preferably the mixer is a fixed mixer located at least in part within the periphery of the vehicle.

Preferably the vehicle has at least three compartments holding dry ingredients, one compartment holding aggregate, one compartment holding fines and one compartment holding cement powder, each compartment having a conveyor, the conveyors of the aggregate and fines being dispersed to combine the aggregates and fines together prior to the cement powder being added.

In order that the present invention may be more readily understood and be put into practical effect reference will now be made to the accompanying drawings which illustrate preferred embodiments and wherein:- Figure 1 is a schematic side view of a vehicle according to the present invention; Figure 2 is a section through a vehicle similar to Figure 1; Figure 3 is a side view illustrating another embodiment; Figure 4 is a transverse section through Figure 3; Figure 5 is a plan view illustrating a typical arrangement for metering and conveying; Figure 6 is a further embodiment; and Figure 7 is an embodiment particularly suited to pumped concrete.

Referring to Figure 1 there is illustrated a vehicle 10 having a compartment 11 holding blended aggregate and sand and a compartment 12 holding cement powder. An auger 13 carries the aggregate and sand to a mixer 14 coupled to the rear of the vehicle 10. As the aggregate and sand passes below the compartment 12 cement powder is dispensed by a paddle wheel dispenser 15 where the last stages of the auger 13 pre-coats the aggregate and sand with cement powder before delivering it into the mixer 14 where water is added. The paddle wheel 15 and the auger 13 are controlled to ensure the ratio between cement powder and the aggregate sand mix remains constant. This may be achieved electronically or mechanically. Mechanically, this may be achieved by having a common drive and appropriate gearing to achieve the desired ratio (see for example Figure Figure 2 illustrates an alternative whereby the tank 11 is divided into two tank sections 16 in 17, the tank sections 16 and 17 extending longitudinally and having their own augers 18 and 19. The cement powder may be delivered using two paddle wheels. Aggregate is held in tank section 16 while sand is held in tank section 17.

Figures 3, 4 and 5 illustrate another embodiment where the vehicle comprises a trailer 20 carrying a tubular container 21 divided into four compartments 22, 23, 24, and 25, the dividers defining the compartments being shown in broken outline. The compartment 22 holds water, the compartment 23 holds aggregate, the compartment 24 holds sand and the compartment 25 holds cement powder. In this case the cement powder in compartment 25 is held under constant pressure aeration to prevent it compacting. Three augers are employed, an auger 26, an auger 27 and an outlet auger 28, the augers 26 and 27 being driven by a common drive shaft 30 which also is common to the paddle wheel 29 delivering cement powder to the outlet auger 28. The outlet auger 28 is also driven via the same drive shaft 30 from drive 31. The augers and paddle wheel are coupled to the drive shaft 30 using suitable sprockets and chain settings to determine the ratio of dry ingredients. It will be realised that this common drive keeps the ratio constant since any resistence that might slow one auger will slow the whole drive assembly the same amount. Water is pumped from tank 22 through a metre related to the rotation of the paddle wheel 29. A mixer 14 is also employed at the rear of the tank. The section through the tank is illustrated in Figure 4.

Sliding doors are employed between the augers 26 and 27 and their respective compartments so that the augers may be kept clear of compacted aggregate or sand that may arise in transit. The doors are not illustrated in Figure 3.

Figure 6 shows a slightly different arrangement of augers since in this case there is a single compartment 32 holding blended aggregate and sand which flows onto the auger 33 and then in turn onto an outlet auger 34 where cement powder is added via the auger 35 from a cement powder tank 36 ultimately being combined in the mixer 14. The augers may be driven by a common drive arrangement and similar configurations to the embodiment of Figure Figure 7 illustrates an embodiment particularly suited to pumped concrete where concrete can be pumped directly from a rear hopper 37 by reason of the auger 38 having a mixer 39, water is introduced from the tank 22 after cement powder is introduced via an auger 40 from cement tank 41. Thus the mix delivered 6 into hopper 37 is fully blended ready to be pumped. It will be appreciated that a cement pump may be mounted directly in the position of hopper 37 and transported with the vehicle.

Whilst the above has been given by way of illustrative example of various forms of the present invention many modifications and variations will be apparent to those skilled in the art without departing from abroad ambit and scope of the invention as herein set forth in the appended claims. For example the augers may be housed in flexible rubber tubes the prevent jamming. The outlet auger in Figure 3 may be replaced by an endless conveyor belt and so on.

Claims (4)

1. A vehicle having compartments holding separate the dry ingredients for concrete, a mixer downstream of the compartments for receiving the ingredients and mixing them together, characterised in that, the vehicle is of the non-tipping type and the relative quantities of ingredients are controlled to remain constant during a mixing cycle, the dry ingredients delivered to the mixer being controlled continuously by means of metering and conveying means automatically maintaining the relative relationship between the amounts of dry ingredients throughout a mixing cycle for practical consistency of the mix throughout the cycle.

2. The vehicle according to claim 1 wherein the metering and conveying means are linked mechanically by a longitudinally extending common drive shaft.

3. A vehicle according to claim 1 or claim 2 wherein the mixer is fixed relative to the vehicle having a discharge point into an inlet adapted to discharge into a concrete pump.

4. A vehicle according to any one of claims 1 to 3 wherein the mixer is a fixed mixer located at least in part within the periphery of the vehicle. A vehicle according to any one of claims 1 to 4 wherein the vehicle has at least three compartments holding dry ingredients, one compartment holding aggregate, one compartment holding fines and one compartment holding cement I 8 powder, each compartment having a conveyor, the conveyors of the aggregate and fines being dispersed to combine the aggregates and fines together prior to the cement powder being added. DATED this TWENTY-SIXTH day of JUNE 2001 ANTHONY LEON STEPHENS By his Patent Attorneys INTELLPRO