IE20090372A1 - Concrete batching system and process - Google Patents

Abstract

The invention provides a process and system for the production of a batch of concrete in a concrete plant and delivering to a desired location, for example a truck mixer, for onward transportation. The plant comprises cement, water and aggregate hoppers, the process comprising the steps of transporting weighed quantities of coarse and/or fine aggregates on a single transport conveyor belt and separating the coarse and fine aggregate using a unique Y-chute positioned at one end of the transport conveyor belt. The invention provides a number of advantages over the prior art, namely greater homogeneity leading to concrete of better quality. <Figure 4>

Description

RatChi nq„ fiVftr.finuacjl Process TBTTr~t3oo Field of the Invention / ϋ< ο The present invention relates to a concrete batching system and process enabling portable mixing of coarse aggregates with pre-mixed mortar (or concrete's mortar), to a homogenous state.

Background to the Invention Currently, there are two main types of batching equipment for manufacturing of concrete when considering portability. The first, more traditional, type of batching equipment is known as a batching plant (also referred to as stationary).

The second type of batching equipment is portable and is known as a volumetric mixer.

Current concrete batching plants can typically operate using one of the following two different methods namely: a) Dry Concrete Batching Systems (DCBS); and b) Wet Concrete Batching Systems (WCBS) At the concrete batching plants dosage of ingredients is 25 usually measured by weight. In such an arrangement, the operator will select the required mix design code name in accordance with the order and the engineering specification for a particular application (concerning compressive strength class, exposure class or classes, consistence class or classes, required workability, etc).

In the DCBS system, as illustrated in Figure 1, during one batch all weighed and/or measured ingredients are discharged IE 090 3 72 together (or in sequences) into a Truck-Mixer but without prior premixing. The advantage of this method is short truck loading time.

However the main problem with this method of batching concrete is that it does not guarantee homogeneity of produced concrete. It is also very difficult to achieve good suppression of cement dust emissions. Also, delays are likely to occur if there is a need for a load to be checked by quality control technicians before leaving the production plant. Other problems with this concrete batching method is that the only type of transporting vehicle that can be used for carrying a load of concrete to construction site is the Truck-Mixer as after discharging of the concrete ingredients they need to be mixed.

In the WCBS, as illustrated in Figure 2, during one batch all weighed and/or measured ingredients are first premixed (all together in the Stationary-Mixer) prior to discharging of the ingredients into Truck-Mixer or into/onto any other Transporting/Mixing/Agitating Vehicle. This method of batching concrete usually provides high quality and uniformity of final product.

UK patent publication number GB2 171 091, Sumitomo Corporation, discloses a system where fine aggregate is mixed with cement and water in a first mixer and that mixture is subsequently mixed with coarse aggregate in a second mixer. US patent number US4,403,863 shows a similar system.

The main problem with this method of batching concrete is that it is not energy and time efficient. Complex systems are required for the weighing of materials in addition to a IE 0 9 0 3 72 number of conveyers to deliver the fine and coarse aggregates for mixing. A further disadvantage of WCBS is that the concrete may deteriorate in transit, especially with highly aerated concrete.

Concrete plants can be made installed on trailers and mounted any place i.e. construction site. Concrete plants may also be in the regime of continuous production (continuous mixer) where a batch is not considered as a certain amount of concrete produced in one cycle of mixer/plant operations but is considered as quantity of concrete produced/discharged during one minute of continuous work of such plant (see EN-206-1 point 3.1.19).

With volumetric mixer concrete batching systems the materials required for the concrete mix are transported to the site in separate hoppers on a vehicle. When the concrete is required, the separate components are steadily added to a mixing apparatus (auger) , also on board the vehicle, in the appropriate proportions to provide a steady continuous supply of the required concrete mix. The concrete mix can be supplied as and when required.

There are several advantages with volumetric mixers. Firstly, if different mix designs are required at one or several different sites, the operator can vary the components of the concrete. This is normally done by altering the gate settings on the aggregate bin, while keeping the cement feed constant. Secondly, a suitable accelerator can be injected at the mixing apparatus (auger) in order to rapidly set the concrete. A third advantage is that, since the constituents of the mix are transported to the site separately, the concrete is always fresh and does IE 0 9 0 3 7 2 not deteriorate in transit.

On the other hand, a disadvantage/problem with volumetric mixers currently available is that the quality and reliability of the concrete mix may not be very high, since the proportions of the components are dependent on the skill of the operator. For example, a gate on a particular component hopper may be set incorrectly; thereby resulting in an inappropriate mix for the particular application or all the component supplies may be set too high resulting in a supply rate which is too high for the particular application. It is important as well that the dosage of ingredients by volume or time of discharge is usually less accurate than dosage by mass (weight).

PCT patent publication number WO96/28290, Melvin Black, describes a portable mixing plant and teaches by not mixing gravel in the batch discharge mixer the power requirements and capacity of the plant are markedly improved. However this system requires a number of moving conveyor belts. The system disclosed is limited and suffers from the aforementioned problems. FR265Q617 and DE2645283 describe similar systems.

There is therefore a need to provide a concrete batching system and method to overcome the above mentioned problems/disadvantages.

Summary of the Invention According to the present invent ion there is provided, as set out in the appended claims a process for the production of batch concrete in a concrete plant and delivering to a desired location, for example a truck mixer, for onward IE 0 9 0 3 72 transportation, said plant having cement, water and aggregate weighing hoppers, the process comprising the steps of: transporting weighed quantities of coarse and/or fine aggregates on a single transport conveyor belt; separating the coarse and fine aggregate using a single Y-chute positioned at one end of the transport conveyor belt; delivering the fine aggregate from said t ransport conveyor belt to a fine aggregate holding hopper and into a stationary mixer, by selective control of said Y-chute; delivering the coarse aggregate from said transport conveyor belt to a coarse aggregate holding hopper, by selective control of said Y-chute; providing a cement weighing hopper for storing cement and an optional water weighing hopper for storing water and a stationary hopper; pre-mixing in said stationary mixer desired quantities of fine aggregate, cement and water delivered from the fine aggregate holding hopper, cement weighing hopper and water weighing hopper to provide premixed concrete mortar; discharging the premixed concrete mortar from the stationary mixer and the coarse aggregate from the coarse aggregate holding hopper to the desired location.

The present invention provides a number of advantages over the prior art, namely greater homogeneity leading to concrete of better quality. The inventive Y-Chute is a mechanism designed to distribute into two (or more) separate destinations the fine and coarse aggregate materials IE Ο 9 0 3 72 delivered to it to greatly simplify the overall process. Heretofore, all other concrete processes used at least two conveyors to separate the fine and coarse aggregate materials. Alleviation of discharging problems is achieved as the final discharge chutes are much less likely to block due to the separation of the coarse aggregate from the other ingredients. This is very advantageous. Significant decreasing of the mixer's abrasion is achieved when compared with WCBS. The invention provides energy efficiency, as smaller mass requires less force for mixing. Increase in transport efficiency is also achieved due to shorter loading period. The invention provides better dust suppression as the volume of coarse aggregates is not pushing out dusty air from the Stationary-Mixer. In addition prevention of the Cement Weighing Hopper from air-locking is achieved as volume of materials discharged into the Stationary-Mixer is smaller; therefore pressure inside of the Stationary-Mixer during loading is decreased and thus providing greater ease of cement discharge.

Ideally the desired location is a truck mixer and the premixed concrete and the coarse aggregate are mixed to a homogenous state, Optionally the invention provides the additional step of adding fibres to the coarse aggregate in the coarse aggregate holding hopper.

In one embodiment the inventive process performs the steps of simultaneously weighing cement and bulk powder additions and delivering separately to the stat ionary mixer simultaneously to the weighing and delivery of said fine aggregate to said stationary mixer. This step greatly IE 0 9 0 3 72 increases the efficiency of the process and saves on time and energy costs.

Ideally the invention provides the step of weighing said fine aggregate and the coarse aggregate separately on said transport conveyor belt. The advantage of this is that only a single weighing means is required, thus simplifying the overall process.

In another embodiment of the present invention there is provided a system for the production of batch concrete in a concrete plant and delivering to a desired location, for example a truck mixer, for onward transportat ion, said plant having cement, water and aggregate weighing hoppers, the system comprising: means for transporting weighed quantities of coarse and/or fine aggregates on a single transport conveyor bel t; means for separating the coarse and fine aggregate using a single Y-chute positioned at one end of the transport conveyor bel t; means for delivering the fine aggregate to a fine aggregate holding hopper; means for delivering the coarse aggregate to a coarse aggregate holding hopper; means for providing a cement weighing hopper and an optional water weighing hopper and a stationary hopper; means for pre-mixing in a stationary mixer desired quantities of fine aggregate, cement and water delivered from the fine aggregate holding hopper, cement weighing hopper and water weighing hopper to provide premixed concrete mortar; means for discharging the premixed concrete mortar IE 0 9 0 3 72 from the stationary mixer and the coarse aggregate from the coarse aggregate holding hopper to the desired location.

There is also provided a computer program comprising program instructions for causing a computer program to carry out the above method which may be embodied on a record medium, carrier signal or read-only memory.

Brief Description of the Drawings The invention will be more clearly understood from the following description of an embodiment thereof, given by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is a workflow diagram of a dry concrete batching system; Figure 2 is a workflow diagram of a wet concrete batching system; Figure 3 is a workflow diagram according to the present invention; and Figure 4 illustrates an exemplary view of the stationary concrete mixer based plant and system of the present invention.

Detailed Description of the Drawings Referring to Figure 3 there is illustrated a workflow diagram of the present invention indicated generally by the reference numeral 1.

Figure 4 shows cement and water and fine aggregate weighing hoppers 2, 3, 4 coupled to a stationary mixer 5.

In addition separately coupled to the stationary mixer 5 is fine aggregate holding hopper 4 where the main IE 0 9 0 3 72 weighing process is realised on the weighing belt. On it firstly a fine aggregate should be dosed and secondly (after discharging of fines into the fine holding hopper) a coarse aggregate is weighed and transported to the coarse holding hopper. Both of the holding hoppers can be equipped with weighing cells to ensure that all material which has been weighed on the belt has been transported into holding hopper and also in the next step of the batch sequence to ensure that all the material from the holding hopper has been fully discharged to the final destination (Truck-Mixer or Stationary-Mixer). Coarse aggregate bin hopper Ί is separately connected through the aggregate weighing belt to the coarse aggregate holding hopper 8, which is in communication with the Truck-Mixer 6 through the final discharge chute.

Fine aggregate bin hopper 13 is connected through the aggregate weighing belt to the fine aggregate holding hopper 4 wherefrom fine aggregate is introduced into the Stationary-Mixer 5.

Concrete-mortar can be made by pre-mixing in the Stationary-Mixer 5 desired quantities of the ingredients delivered from the fine aggregate holding hopper 4 and from the cement and water weighing hoppers 2 and 3. It will be appreciated that the separation of ingredients allows quicker turnaround for mixing and loading times, while saving energy.

Pre-mixing in the stationary mixer 5 can include the following ingredients, fine aggregate, cements, bulk powder additions, admixtures and other desired ingredients which have impact on the properties of the IE 0 9 0 3 72 ready mixed concrete in any desired combination (either in a fresh or hardened state or both).

It will be appreciated that the required quantity of coarse aggregate is kept separate from the fine aggregate as discussed in detail below as the coarse aggregate is not pre-mixed in the stationary mixer 5. Control of the work flow diagram can be implemented by control of computers and associated controller software.

In operation, the process of the present invention is illustrated by Figure 4 and generally indicated by the reference numeral 20. A single conveyor weighing belt 21 is provided to dose by weight and transport the required quantities of the coarse and/or fine aggregate to the selected holding hopper. A Y-chute 22 is provided at one end of the transport conveyor beit 21 to direct the fine and coarse aggregate into separate hoppers. The Y-chute 22 provides selective control for directing the relevant aggregate to the required hopper using an automatic or manual control means. Weighing of the aggregate ingredients starts with fine aggregate (for efficiency reasons). After the total quantity has been weighed up, the fine aggregate is transported into the fine aggregate holding hopper 4. The fine aggregate is discharged into the Stationary Mixer 5 for slurry mixing (with the rest of the concrete-mortar ingredients) which is followed by its discharge into a Truck-Mixer (not shown) through final discharge chute 23. Optionally, if no coarse aggregate is required the mixed fine aggregate can be separately discharged though discharge chute 24 to a desired location.

IE 0 9 0 3 72 The inventive Y-Chute 22 is a mechanism designed to distribute into two (or more) separate destinations any suitable materials delivered to it. It will be appreciated that usage of one single belt for transporting aggregates (or any other ingredients) in combination with the Y-Chute 22 and more than one Holding/Weighing Hoppers assembled provided the best and most advantageous embodiment for the present invention, in combination with proper sequencing set up using a process controlling computer. Only a single conveyor 21 is required by using the Y-chute 22. Other automatic or manual methods/procedures for the controlling of the Y-chute 22 and the single conveyor belt 21 of the present invention may also be provided.

In a further aspect of the invention, after the fine aggregate has been discharged from the aggregate weighing belt 21, coarse aggregate is weighed on the weighing belt 21 and transported into the coarse aggregate holding hopper 8, via the Y-chute 22, wherefrom it is discharged through the final discharge chute 23 into the Truck-Mixer thereby bypassing the Stationary-Mixer 5. Simultaneously, to the process of weighing of the aggregates the weighing of the other ingredients is started. Cement and bulk powder additions are weighed in cement weighing hopper wherefrom they are introduced into the stationary mixer 5.

It should be appreciated that the stationary mixer 5 premixes desired quantities of fine aggregate, cement and water delivered on the fine aggregate holding hopper, cement weighing hopper and water weighing hopper to provide pre-mixed concrete mortar. The water can be dosed by a number of means, e.g. weighed in the water-weighing IE 0 9 0 3 7 2 hopper, wherefrom it is discharged into the stationary mixer 5. Another method is to use volume dosage by measuring the amount of water introduced into the Stationary-Mixer. The same applies to the admixtures (and any other liquids) which can be introduced to by mass or volume depending on the ingredients and technology/method used.

Discharging of the pre-mixed concrete-mortar from the Stationary-Mixer 5 and the coarse aggregate from the coarse aggregate holding hopper 8 are controlled by an operator or a computer program or a combination of both. The desired location is typically a Truck-Mixer, inside its drum the pre-mixed concrete's-mortar and the coarse aggregate can be mixed off site to a homogonous state. Different kinds of fibres can be added directly to the conveyor system and preferably with the coarse aggregate.

It will be appreciated that the Stationary-Mixer working in the regime of present invention may have less capacity than conventional Stationary-Mixer with no negative effects on the plant's production capacity.

The embodiments in the invention described with reference to the drawings comprise a computer apparatus and/or processes performed in a computer apparatus. However, the invention also extends to computer programs, particularly computer programs stored on or in a carrier adapted to bring the invention into practice to control the process according to the appended claims. The program may be in the form of source code, object code, or a code intermediate source and object code, such as in partially compiled form or in any other form suitable for use in the implementation IE 0 9 0 3 7 2 of the method according to the invention. The carrier may comprise a storage medium such as ROM, e.g. CD ROM, or magnetic recording medium, e.g. a floppy disk or hard disk. The carrier may be an electrical or optical signal which may be transmitted via an electrical or an optical cable or by radio or other means.

The words comprises/comprising and the words having/including when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The invention is not limited to the embodiments hereinbefore described but may be varied in both construction and detail.

Claims (8)

Claims

1. A process for the production of batch concrete in a concrete plant and delivering to a desired location, for example a truck mixer, for onward transportation, said plant having cement, water and aggregate weighing hoppers, the process comprising the steps of: transporting weighed quantities of coarse and/or fine aggregates on a single transport conveyor belt; separating the coarse and fine aggregate using a single Y-chute positioned at one end of the transport conveyor belt; delivering the fine aggregate from said transport conveyor belt to a fine aggregate holding hopper and into a stationary mixer, by selective control of said Y-chute; delivering the coarse aggregate from said transport conveyor belt to a coarse aggregate holding hopper, by selective control of said Y-chute; providing a cement weighing hopper for storing cement and an optional water weighing hopper for storing water and a stationary hopper; pre-mixing in said stationary mixer desired quantities of fine aggregate, cement and water delivered from the fine aggregate holding hopper, cement weighing hopper and water weighing hopper to provide premixed concrete mortar; discharging the premixed concrete mortar from the stationary mixer and the coarse aggregate from the coarse aggregate holding hopper to the desired location. IE 0 90 3 72

2. The process of claim 1 comprising the additional step of weighing said fine aggregate and said coarse aggregate separately on said transport conveyor belt.

3. The process of claims 1 or 2 wherein the desired location is a truck mixer and the pre-mixed concrete and the coarse aggregate are mixed to a homogenous state.

4. The process of any preceding claim comprising the additional step of adding fibres to the coarse aggregate in the coarse aggregate holding hopper before mixing.

5. The process of any preceding claim comprising the steps of weighing cement and bulk powder additions and delivering separately to the stationary mixer, simultaneously to the weighing and delivery of said fine aggregate to said stationary mixer.

6. A system for the production of batch concrete in a concrete plant and delivering to a desired location, for example a truck mixer, for onward transportation, said plant having cement, water and aggregate weighing hoppers, the system comprising: means for transporting weighed quantities of coarse and/or fine aggregates on a single transport conveyor belt; means for separating the coarse and fine aggregate using a Y-chute positioned at one end of the transport conveyor belt; means for delivering the fine aggregate to a fine aggregate holding hopper; means for delivering the coarse aggregate to a coarse aggregate holding hopper; IE 0 9 0 3 72 means for providing a cement weighing hopper and an optional· water weighing hopper and a stationary hopper; means for pre-mixing in a stationary mixer desired 5 quantities of fine aggregate, cement and water delivered from the fine aggregate holding hopper, cement weighing hopper and water weighing hopper to provide premixed concrete mortar; means for discharging the premixed concrete mortar 10 from the stationary mixer and the coarse aggregate from the coarse aggregate holding hopper to the desired location.

7. A system or process as substantially hereinbefore 15 described with reference to the accompanying description and/or Figures 3 and 4.

8. A computer program comprising program instructions for causing a computer to control the process of any one of 20 claims 1 to 5.