IE77873B1 - A process for making readymix concrete - Google Patents

Abstract

The invention concerns a process for making readymix concrete in batches of pre-determined composition for discharge to a delivery truck. Details of the batch size and composition are inputted to a computer-operated data processing system. The system initiates the discharge of an appropriate aggregate mix, which may include sand, grit and/or stone chips, to an aggregate weight hopper which controls the weight of aggregate to be used in the batch, and automatically feeds the required weight of aggregate to a concrete mixer. The control system determines the required volume of cement needed to make the batch and signals the discharge of cement from a silo to a cement weigher which delivers the required amount of cement to the concrete mixer. The control system also determines the required amount of water needed to make the concrete batch and initiates the discharge of water for addition to the batch. The invention includes apparatus for carrying out the process.

Description

A PROCESS FOR MAKING READYMIX CONCRETE Field of the Invention The invention relates to a process for making readymix concrete. In particular the invention concerns a process and apparatus for preparing batches of readymix concrete for discharge to a delivery truck.

Object of the Invention It is the object of the invention to provide a readymix concrete batching facility and process which is capable of despatching concrete to a delivery truck, without operator assistance and in doing so achieving maximum tolerance in concrete quality.

Summary of the Invention The invention provides a process for making readymix concrete in batches for discharge to a delivery truck, each batch containing concrete of a required composition, comprises entering details of the batch size and composition into control means comprising a computer-operated data processing system, whereupon the control means initiate the discharge of an appropriate aggregate mix, which may include sand, grit and/or stone chips, to an aggregate weight hopper which controls the weight of aggregate to be used in the batch, automatically feeding the required weight of aggregate to a concrete mixer, and wherein the control means determines the required volume of cement needed to make the batch and signals the discharge of cement from a silo to a cement weigher which delivers the required amount of cement to the concrete mixer, and wherein the control means also determines the required amount of water needed to make the concrete batch and initiates the discharge of water for addition to the batch. 1631S - 2 778 73 The control means controls discharge of aggregate from one or more of a plurality of holdings bins to the aggregate weight hopper, and wherein the supply of aggregate to the bins is monitored by high and low level probes located in the bins which signal the control means to control the feed of aggregate to the bins from an aggregate intake hopper.

Suitably, each holding bin contains a moisture probe which relays a signal/value to the control means which automatically adjusts the weight of aggregate supplied to the concrete mixer, and also determines the amount of water needed to make up the batch of concrete.

In a preferred embodiment, each concrete delivery truck is provided with transmitter means, and a signal is sent from said transmitter means to the control means to commence preparation of the concrete batch required, and the batching process is initiated by the inputting into the control means of a PIN by the driver of the delivery truck.

Brief Description of the Drawings One embodiment of the invention is hereinafter described with reference to the accompanying drawings wherein: Figure 1 is a schematic drawing of a readymix plant according to the invention; and Figure 2 is a side view of the plant of Figure 1.

Detailed Description of the Preferred Embodiment The invention concerns a control process and apparatus involving the use of a computer-operated data processing system. The system is an automated batching control system which allows for orders for readymix concrete to be pre-programmed, batched and despatched without operator assistance. - 3 Referring to the drawings, these show a readymix concrete batching plant operated by the control system of the invention.

The plant comprises a raw material aggregate intake hopper 1 which / £ contains a supply of suitable aggregate. Aggregate is fed into the hopper 1 by means of a mechanical shovel (not shown). The hopper 1 has a cam-shell door which controls the feed rate of aggregate to a radial conveyor 2. The conveyor 2 has a chevron belt to ensure maximum handling efficiency.

A flow sensor switch 3 is provided on the outlet of the hopper 1.

The switch initially activates a vibrator to empty the hopper completely. The sensor will automatically stop the conveyor 2 after a predetermined time has elapsed with no flow of material.

The purpose of the hopper 1 is to feed aggregate to four individual aggregate holding bins 4, 5, 6 and 7. Each of the bins contains a different type of aggregate for use in preparing concrete mixes of different composition. For example, bins 4 and 5 each contain a different type of sand, while bin 6 contains grit, and bin 7 contains stone chips. As the aggregate in the bins is depleted, they are refilled from the hopper 1 by means of the radial conveyor which can swing over each of the bins. The bins are provided with high level probes which are connected to the control means. Thus when the aggregate reaches a predetermined level in the bins an alarm is sounded and the conveyor 2 is shut down to avoid overfill.

The bins are also provided with low level probes connected to the control means. These sense when there is insufficient quantities of material available to the bins to complete a batch of concrete. The control means initiate both sound alarms and light indicators on the hopper which identify the hopper and aggregate type to be manually refilled.

Each holding bin 4, 5, 6 and 7 contains a moisture probe which relays a signal/value to the control means which automatically adjusts the batch weight +/- to ensure that each batch contains the precise weight of aggregate required. This moisture value is also used to - 4 adjust the volume of water required at the mixing stage of the process to complete the batch of concrete. The weight of aggregate required for each batch is present and selected when selecting a grade of concrete from a control menu presented on the cdmput6r controlling the system i.e. establishing an order.

The weight is controlled by feeding the aggregate from one of the designated bins 4, 5, 6 and 7 to an aggregate weight hopper 9.

The aggregate weight hopper is mounted on load cells which control the required weight. Each individual aggregate is gravity fed from the appropriate storage bin 4, 5, 6 or 7 to the weight hopper 9 and on reaching the required weight is fed via a belt conveyor 11 to a concrete mixer 12.

As each aggregate is fed into the mixer 12 a required volume of cement (determined by the specific concrete grade selected on the computer) is fed by a screw conveyor 13 from a cement silo 14 to a cement weigher 15. The cement silo 14 is supplied with cement from a larger cement silo 8.

From the weigher 15 the cement is gravity fed to the concrete mixer 12. This ensures that the maximum dry mixing time of aggregate occurs with minimum disruption to the batching process, and with maximum time efficiency in the batching/despatch of concrete.

The cement weight hopper 15 is mounted on load cells and the cement is discharged from the hopper via a butterfly valve to the concrete mixer 12. A vibrating motor combined with the load cells is used to ensure that the total contents of the weigher hopper 15 are emptied into the mixer 12.

Moisture probes/pan mixer probes mounted in the floor of the concrete mixer 12 are used to ensure that sufficient water is added to the concrete batch to ensure correct water/cement ratio and concrete workability. On reaching the prescribed moisture content, the batch is automatically released through a discharge chute 19 into a prescribed readymix concrete delivery truck 20. - 5 Additives are automatically preselected when the initial grade is selected from the menu. Each additive is independently fed to the mixer 12. Liquid based additives are directly fed into the water feed to the mixer 12, and their precise volume is controlled by flow monitors, and release valves, mounted on the outlet of their individual holding tanks 21.

Provision is made to all for powdered additives to be belt weighed and gravity fed as required to the mixer 12. 30N 20 Quantity 7 Metres /11/95 8am Miles 2 Hours XXX XXX Pulverised fuel ash (PFA) is stored in a silo 16 and fed via a screw conveyor 17 to the cement weigher hopper 15. PFA can be used as a cement replacement in some mixes.

On receipt of an order the sales office can designate the specific order to a specific readymix concrete delivery truck and the estimated time for batching is automatically recorded by the required delivery date, time, and distance from the plant in miles.

EXAMPLE Order received from: on 10/11/95 : J. Soap Ltd.

Grade: Date Required: Time: Di stance/Deli very: Milage: Time for Delivery: Truck Designated: A transmitter is mounted on the cab of the truck sends a signal to a receiver of the control means which automatically boots up the order and the batch required.

The driver of the truck can then initiate the batching process by inputting a personal identification number (PIN) number to a control panel of the control means. The batching will only be carried out if the truck is in its correct position for loading under the discharge chute 19 of the batching plant.

Claims (5)

1. A process for making readymix concrete in batches for discharge to a delivery truck, each batch containing concrete of a required 5 composition, comprises entering details of the batch size and composition into control means comprising a computer-operated data processing system, whereupon the control means initiate the discharge of an appropriate aggregate mix, which may include sand, grit and/or stone chips, to an aggregate weight hopper which controls the weight of 10 aggregate to be used in the batch, automatically feeding the required weight of aggregate to a concrete mixer, and wherein the control means determines the required volume of cement needed to make the batch and signals the discharge of cement from a silo to a cement weigher which delivers the required amount of cement to the concrete mixer, 15 wherein the control means also determines the required amount of water needed to make the concrete batch and initiates the discharge of water for addition to the batch and whereupon the control means may initiate the release of the concrete batch to the delivery truck. 20

2. A process as claimed in claim 1, wherein the control means controls discharge of aggregate from one or more of a plurality of holdings bins to the aggregate weight hopper, and wherein the supply of aggregate to the bins is monitored by high and low level probes located in the bins which signal the control means to control the feed of 25 aggregate to the bins from an aggregate intake hopper.

3. A process as claimed in claim 2, wherein edch holding bin contains a moisture probe which relays a signal/value to the control means which automatically adjusts the weight of aggregate supplied to the concrete 30 mixer, and also determines the amount of water needed to make up the batch of concrete.

4. A process as claimed in any of the preceding claims, wherein each delivery truck is provided with transmitter means, and a signal is sent 35 from said transmitter means to the control means to commence preparation of the concrete batch required, and the batching process is initiated by the inputting into the control means of a PIN by the driver of the delivery truck. - 7

5. A process and/or apparatus for making readymix concrete substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.