AU2011200321B2 - System and Method for Reclaiming Unused Portions of Concrete - Google Patents

Abstract

Abstract The present invention provides a method for reclaiming concrete from unused concrete returning from site. The method comprises determining whether the concrete may be used before measuring the weight of the concrete to be 5 reclaimed. The method then comprises the step of calculating the required dose an a stabilising agent required to suspend the setting process before adding the required dose of stabilising agent to the unused concrete. -14-

Description

E'/U/l 'I 25/o/u1 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Murray Hender Actual Inventor Murray Hender Address for service is: WRAYS Ground Floor, 56 Ord Street West Perth WA 6005 Attorney code: WR Invention Title: System and Method for Reclaiming Unused Portions of Concrete The following statement is a full description of this invention, including the best method of performing it known to me: -1- System and method for Reclaiming Unused Portions of Concrete Field of the Invention The present invention generally relates to a system and method for reclaiming unused portions of concrete for later use. 5 Background Art With the ongoing and intensifying focus of taking care of our environment, numerous different processes are constantly under review. Improvements to these processes are typically coupled with improving the efficiency of the process, often by recycling or reusing products that were previously discarded to 10 landfill. One such process where improvements can be made is in relation to the concrete industry. Currently, concrete is typically a mixture in inert materials such as aggregate and sand mixed with a binder being cement and water prepared as liquid at a distribution site. Trucks with a revolving agitator then 15 transport the liquid concrete to the location where it is poured to provide the required structure. On the way to the location it is essential that the agitator revolves and that the concrete is continually mixing to prevent settling. Once the chemical reaction between the cement begins the only way to prevent the concrete from hardening is with additive intervention or separation through 20 washing the concrete with large amounts of water to separate the cement from the inert materials. Generally, the trucks are filled with an ordered amount of concrete so as to supply a customer with enough concrete to complete their order. Typically, for each order, there will be varying amount ordered in excess and in any one day 25 there can be many different orders, most having a small to large percentage left over. Once a truck returns from a completed job at any time of the day, any remaining concrete in the truck is poured/washed from the truck and discarded. It is estimated that in Australia over 3.5 million tonnes of discarded concrete is placed into landfill. -2- The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was part of the common general knowledge as at the priority date of 5 the application. SUMMARY OF INVENTION It is an object of this invention to provide a system which reclaims at least a portion of concrete which would otherwise be discarded. The present invention provides a method for reclaiming concrete using unused 10 concrete returning from a site in an agitator, the method comprises: determining whether the unused concrete may be used; measuring the weight of the unused concrete to be reclaimed; measuring a load on the agitator from the unused concrete; calculating the required dose of a stabilising agent required to suspend 15 the setting process of the unused concrete based on at least the measured load on the agitator from the unused concrete; adding the required dose of stabilising agent to the unused concrete to provide reclaimed concrete; and adding the reclaimed concrete and new concrete together at a desired 20 percentage to provide a concrete mix embodying the required concrete properties. The percentage of reclaimed concrete in the concrete mix is such that it does not affect the setting time of the newly produced concrete. Preferably the new concrete overpowers the reclaimed concrete to allow the setting process to -3commence. Preferably there is 5% reclaimed concrete with 1% additive per cement content. The step of determining whether the concrete may be used requires determining whether the age of the concrete is within the required parameters. Typically this 5 is around two hours old, but depends on the normal rules of concrete setting such as ambient temperature, cement content; age, additives such as water reducers or accelerators, all are variable. The step of measuring the weight of the concrete may require measuring the weight of a storage agitator in to which the unused concrete is to be received, 10 and then measuring the weight of the storage agitator once the unused concrete has been poured therein. The difference may then be used to assist in determining the amount of additive required to stabilize the concrete. The step of calculating the required dose includes placing the figures on a spreadsheet, the spreadsheet information may include docket number, time, 15 weights, cement content of the mix. The spreadsheet may calculate cement content and additive relative to the concrete in the storage agitator. The load on the electric motor and hydraulics are monitored as the concrete begins to hydrate in the concrete agitator. The load is monitored by the PLC that takes constant readings of the load on the electric motor and the hydraulics. Based on the load 20 readings, the required amount of stabiliser needed to be added to maintain the concrete in a stabilised state can be added automatically through instruction by the PLC as needed. The step of adding together reclaimed concrete and new concrete may also comprise the step of calculating the allowed quantity of reclaimed concrete which 25 may be mixed with new concrete. The spreadsheet may calculate the difference in cement content and amount of variance between the reclaimed concrete and new concrete. The present invention provides a method for reclaiming concrete for mixing in predetermined portions with new concrete in an agitator, the method comprises -4adding a stabilising agent to an unused portion of concrete as it returns in a truck from a site, the stabilising agent blocking the hydration of the cement before it completes its initial setting stage, wherein the system measures the load placed on the agitator from the unused portion of the concrete and calculates the 5 amount of stabilising agent to add to the unused portion of concrete based on the load measured. The method may also comprise mixing the reclaimed concrete with a new batch of concrete as the new batch of concrete is loaded into a truck. Any stabilization agent can be used. One such type is Sikatard *. 10 The additive suspends the setting of the reclaimed concrete until it can be added to a new batch of concrete. Preferably the reclaimed concrete is mixed with the new batch of concrete to provide a concrete mix. The predetermined ratio may be such that the new batch of concrete overpowers the effect of the stabilising agent to allow the concrete mix to set. 15 Tests conducted to date have indicated that the mixing of a predetermined portion of the reclaimed concrete together with the new batch of concrete provides concrete of increased strength. The present invention provides a system for reclaiming concrete for mixing in predetermined portions with new concrete in an agitator, the system adds a 20 stabilising agent in to an unused portion of concrete which has returned in a truck from a site, the stabilising agent blocking the hydration of the cement before it completes its initial setting stage, wherein the system measures the load placed on the agitator from the unused portion of the concrete and calculates the amount of stabilising agent to add to the unused portion of concrete based on 25 the load measured. The system may comprise a storage agitator into which the unused portion of concrete is poured and stored. The stabilising agent may be poured into the storage agitator at the required doses. -5- The doses may be calculated based on various factors including ambient temperature, cement content, and age. The doses may be calculated using a computer program. This will ensure the doses may be calculated by both those with experience in the concrete industry and those who are not. The program 5 may use a spreadsheet. The spreadsheet may use the age of the concrete, the variable cement content and the variable additive dose rate. The dose rate depends on the normal constraints of concrete i.e. the normal rules of concrete setting such as ambient temperature, cement content; age, additives such as water reducers or accelerators, all are variable. 10 The storage agitator may have first measuring means to measure the weight of the agitator and its contents. The measuring means may be in the form of one or more load cells. The load cell may be linked with a digital output. After determining the weight of the reclaimed concrete in the storage agitator, the dose of stabilising agent required may be calculated. 15 The system may also comprise a pump, to pump the reclaimed concrete from the storage agitator into a truck, the pump may incorporate a second measuring means to measure the amount of reclaimed concrete passing into the truck. The second measuring means may be in the form of a magnetic flow meter. The system may comprise a mixing agitator for mixing the reclaimed concrete 20 mix until it is ready for reuse with new concrete. The system may comprise a conveyor to move the concrete to various stations. The present invention further provides a method for reclaiming concrete from unused concrete returning from site in an agitator, the method comprises: determining whether the unused concrete may be used; 25 measuring the weight of the unused concrete to be reclaimed; measuring a load on the agitator from the unused concrete; -6calculating the required dose an a stabilising agent required to suspend the setting process of the unused concrete based on at least the measured load on the agitator from the unused concrete; adding the required dose of stabilising agent to the unused concrete. 5 Brief Description of the Drawings The invention will be better understood by reference to the following description of a specific embodiment thereof as shown in the accompanying drawings in which: Figure 1 is a storage agitator according to an embodiment of the 10 invention; Figure 2 is a schematic of a concrete distribution site employing an embodiment of the current invention; Figure 3 is a schematic of a truck being loaded with reclaimed concrete; Figure 4 is a schematic of a truck unloading unused concrete into the 15 storage agitator; Figure 5 is an example of a calculation spreadsheet which determines how much new concrete needs to be added to the reclaimed concrete; and Figure 6 is a modified view of that shown in figure 5 whereby figure 6 only 20 shows the relevant data to an operator. Best Mode(s) for Carrying out the Invention Referring to the figures, the invention according to the first embodiment is in the form of a method and system to reclaim unused portions of concrete. -7- Upon returning to a concrete distribution site, a truck 15 having an unused portion of concrete from the previous job, must evaluate whether the unused portion is of a suitable age to be reclaimed. If so, then prior to washing the truck 15, the unused portion of concrete is placed into a storage agitator 21by chute, 5 as depicted in figure 4. Referring to figure 1, the storage agitator 21 is coupled with a first measuring means, such as a load cell 23. The load cell 23 measures the weight of the storage agitator 21 both prior to the unused concrete entering the storage agitator 21 and after it is added. The weight readings may be displayed and/or 10 may be feed directly into a computer program from which the required calculations are performed to determine the required amount of a stabilising agent which must be added and/or the required cement content for the new concrete. An example of the calculation output is illustrated in figures 5 and 6. The storage agitator 21 rotates to maintain a homogenous concrete mix. The 15 storage agitator 21 also has a camera 25 to allow for visual inspection of the process from a remote location. The storage agitator 21 may be configured such that a predetermined weight is stored whereby once the storage agitator 21 reaches the predetermined weight no further concrete is delivered into the storage agitator 21. 20 Once the unused concrete is delivered to the storage agitator 21 and the appropriate calculations made, the stabilising agent is added to the storage agitator 21. The unused concrete and stabilising agent are mixed for approximately five minutes to form the reclaimed concrete. The reclaimed concrete can then remain in the storage agitator 21 until such time as it may be 25 mixed with new concrete to form a concrete mix. Figure 2 shows two trucks 15 positioned at a distribution site. One truck 15a is positioned to return the unused portion of concrete to the storage agitator 21 directly through a chute into the storage agitator 21. The second truck 15b is empty and is positioned to receive concrete from the storage agitator 21 along -8the return conveyor 17 . The second truck 15b can subsequently be topped up with a new load of concrete. In the current embodiment both operations need to be conducted independently. Figure 3 shows reclaimed concrete being delivered to the truck 15. The 5 reclaimed concrete is fed onto the delivery conveyor 27 which feeds the reclaimed concrete into the truck 15 before the truck 15 drives to the batch plant to load new concrete on top of the reclaimed concrete. Water spray systems 29 are utilised to reduce build up of concrete on the conveyor 27. The agitator 21 is linked to a PLC (not shown) that will take load readings from 10 hydraulic and electrical motors at certain stages to indicate if the concrete is starting to reduce in slump. This will determine if the hydration process has started and indicates whether more stabiliser or water reducer needs to be added to stop the concrete setting in the agitator 21. Also a temperature reading from infrared. The load readings, determination, addition of stabiliser and 15 temperature readings can be automated or manual. Ambient temperature has a major influence on the setting of the concrete, no direct sunlight onto the concrete agitator is advisable as it heats the metal and starts the setting process early. Also it is preferable if the agitator is shaded and has means of cooling the agitator drum with mist sprays or air conditioning. 20 In an alternative embodiment concrete pumps may be used in place of conveyors. Figures 5 and 6 are illustrative of the calculations used to determine what volume of stabilising agent needs to be added to the unused concrete in order to hold the unused concrete in a state whereby it may later be used, and/or new 25 concrete needs to be added to the unused concrete in order to provide a useful mix of unused concrete and new concrete. The use of this process has the potential to reduce the amount of concrete turned to waste by up to 90%. In Australia an estimated 3.5million tones could be -9kept out of landfill and 285.000 Kilolitres of water saved. In this it would contain about 435.000 tonnes of cement. Carbon saved 350.000 tones. Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention. 5 Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. -10-

Claims (19)

1. A method for reclaiming concrete using unused concrete returning from a site in an agitator, the method comprises: determining whether the unused concrete may be used; measuring the weight of the unused concrete to be reclaimed; measuring the load on the agitator imposed the unused concrete; calculating the required dose of a stabilising agent required to suspend the setting process of the unused concrete based on at least the measured load on the agitator from the unused concrete; adding the required dose of stabilising agent to the unused concrete to provide reclaimed concrete; and adding the reclaimed concrete and new concrete together at a desired percentage to provide a concrete mix embodying the required concrete properties.

2. The method according to claim 1 whereby when adding the reclaimed concrete and new concrete together the percentage of reclaimed concrete in the concrete mix is calculated such that it does not affect the setting time of the newly produced concrete.

3. The method according to claim 2 whereby there is 5% reclaimed concrete with 1 % additive per cement content.

4. The method according to claim 1, 2 or 3 wherein the step of determining whether the unused concrete can be used requires determining whether the age of the unused concrete is within the required parameters. -11-

5. The method according to claim 1, 2, 3 or 4 wherein the step of measuring the weight of the unused concrete requires measuring the weight of a storage agitator in to which the unused concrete is to be received, and then measuring the weight of the storage agitator once the unused concrete has been poured therein. .

6. The method according to any one of the preceding claims wherein the step of calculating the required dose of stabilising agent includes calculating the cement content and stabilising agent additive relative to the concrete in the storage agitator.

7. The method according to any one of the preceding claims wherein the step of adding together reclaimed concrete and new concrete also comprises the step of calculating the allowed quantity of reclaimed concrete which can be mixed with new concrete.

8. A method for reclaiming concrete for mixing in predetermined portions with new concrete in an agitator, the method comprises adding a stabilising agent to an unused portion of concrete as it returns in a truck from a site, the stabilising agent blocking the hydration of the cement before it completes its initial setting stage; wherein the system measures the load placed on the agitator from the unused portion of the concrete and calculates the amount of stabilising agent to add to the unused portion of concrete based on the load measured.

9. The method according to claim 8 further comprising the step of mixing the reclaimed concrete with a new batch of concrete as the new batch of concrete is loaded into a truck. 1O.The method according to claim 8 or 9 wherein the reclaimed concrete is mixed with the new batch of concrete at a predetermined ratio whereby the new batch of concrete overpowers the effect of the stabilising agent to allow the concrete mix to set. -12-

11.A system for reclaiming concrete for mixing in predetermined portions with new concrete in an agitator, the system adds a stabilising agent in to an unused portion of concrete which has returned in a truck from a site, the stabilising agent blocking the hydration of the cement before it completes its initial setting stage; wherein the system measures the load placed on the agitator from the unused portion of the concrete with a load reading means and calculates the amount of stabilising agent to add to the unused portion of concrete based on the load measured with the load reading means.

12. The system according to claim 11 comprises a storage agitator into which the unused portion of concrete is poured and stored, before a stabilising agent is poured into the storage agitator at the required doses.

13. The system according to claim 11 or 12 further comprising a means to calculate the required doses based on various factors including ambient temperature, the age of the concrete, the variable cement content and the variable additive dose rate, the dose rate depending on the concrete properties including ambient temperature, cement content; age, water reducers or accelerators.

14.The system according to claim 11, 12 or 13 wherein the storage agitator has a first measuring means to measure the weight of the agitator and its contents.

15.The system according to claim 14 wherein the measuring means is in the form of one or more load cells, each load cell being linked with a digital output.

16.The system according to any one of claims 11 to 15 further comprising a pump to pump the reclaimed concrete from the storage agitator into a truck, the pump incorporating a second measuring means to measure the amount of reclaimed concrete passing into the truck. -13-

17. The system according to claim 16 wherein the second measuring means is in the form of a magnetic flow meter.

18.The system according to any one of claims 11 to 17 further comprising a mixing agitator for mixing the reclaimed concrete mix until it is ready for reuse with new concrete.

19.The system according to any one of claims 11 to 18 further comprising a conveyor to move the concrete to various stations.

20.A method for reclaiming concrete from unused concrete returning from site in an agitator, the method comprises: determining whether the unused concrete may be used; measuring the weight of the unused concrete to be reclaimed; measuring the load on the agitator from the unused concrete; calculating the required dose an a stabilising agent required to suspend the setting process of the unused concrete based on at least the measured load on the agitator from the unused concrete; adding the required dose of stabilising agent to the unused concrete. -14-