WO2016023119A1

WO2016023119A1 - Method and system for handling ready-mix concrete and method for producing calibration data

Info

Publication number: WO2016023119A1
Application number: PCT/CA2015/050760
Authority: WO
Inventors: Denis Beaupre
Original assignee: I.B.B. Rheologie Inc.
Priority date: 2014-08-15
Filing date: 2015-08-12
Publication date: 2016-02-18

Abstract

The method for handling ready-mix concrete generally has the steps of: rotating the ready- mix concrete in a drum of a concrete mixer, the drum being rotatable about its axis; measuring a viscosity value of the ready-mix concrete in the rotary drum; comparing the measured viscosity value to a threshold viscosity value corresponding to a minimum expected strength of the ready-mix concrete when in a cured state; generating an output signal based on said comparison; and handling the ready-mix concrete based on said output signal.

Description

METHOD AND SYSTEM FOR HANDLING READY-MIX CONCRETE AND METHOD FOR PRODUCING CALIBRATION DATA

FIELD

[0001] The improvements generally relate to the field of handling ready-mix concrete, and more particularly to the field of evaluating and/or adjusting the constitution of ready-mix concrete.

BACKGROUND

[0002] Ready-mix concrete generally includes aggregates, cement and water. Once moulded (cast) into place, the ready-mix concrete hardens during a curing process and yields a cured concrete.

[0003] During the steps of handling the ready-mix concrete, achieving and/or maintaining a satisfactory workability is a concern. It is commonplace in the field to obtain an indication of workability by performing a slump test. The workability can then be adjusted by adding water, aggregates and/or admixtures to the ready-mix concrete.

[0004] In recent years, we have seen a heightened public awareness concerning physical properties of the cured concrete. For instance, events such as collapsing of overpasses over vehicles have particularly influenced the motivation to obtain greater control or certainty over the physical properties of the cured concrete.

[0005] The very nature of the concrete handling process poses a particular challenge to controlling the physical properties of the cured concrete. Actions such as the addition of water, aggregates and/or admixtures changes the composition of the ready-mix concrete which, in turn, affects the physical properties of the cured concrete.

SUMMARY

[0006] It was discovered that there was a strong linear correlation between the compressive strength of the cured concrete and the viscosity of the ready-mix concrete. Moreover, although the slump measurement does not provide a viscosity value (slump can be influenced by many other variables), viscosity of the ready-mix concrete can be directly measured by monitoring the resistance of a probe moving in the ready-mix concrete (see U.S. Patent Application Publication Number 2012/0204625 A1), for instance. Moreover, it was found that while maintaining a minimum viscosity value of the ready-mix concrete is a concern, for the stated reason, adding at least certain types of admixture did not affect viscosity. Henceforth, a method of providing a satisfactory ready-mix composition is provided where water is added to diminish viscosity until reaching the viscosity threshold, and adjusting the yield by the addition of admixture after that point, if required.

[0007] In accordance with one aspect, there is provided a method for handling ready-mix concrete, the method comprising the steps of: rotating the ready-mix concrete in a drum of a concrete mixer, the drum being rotatable about its axis; measuring a viscosity value of the ready-mix concrete in the rotary drum; comparing the measured viscosity value to a threshold viscosity value corresponding to a minimum expected strength of the ready-mix concrete when in a cured state; generating an output signal based on said comparison; and handling the ready-mix concrete based on said output signal.

[0008] In accordance with another aspect, there is provided a system for handling ready- mix concrete comprising: a concrete mixer having a drum for containing ready-mix concrete, the drum being rotatable about its axis; a rheological value sensor mounted in the drum of the concrete mixer and being adapted to measure at least one rheological property value of the ready-mix concrete inside the drum of the concrete mixer; and a computing device operatively connected to the rheological value sensor and being adapted to compare the measured at least one rheological property value to a corresponding threshold value, the computing device being further adapted to generate an output signal based on said comparison, and adapted to handle the ready-mix concrete based on said output signal.

[0009] In accordance with another aspect, there is provided a method of producing calibration data, the method comprising the steps of: providing a plurality of samples of ready-mix concrete, the plurality of samples having varying, known viscosity values; curing the plurality of samples of ready-mix concrete obtaining a plurality of cured samples; measuring the compressive strength value of each one of the plurality of samples of cured samples; and associating the compressive strength values to corresponding viscosity values to produce said calibration data. [0010] In accordance with another aspect, there is provided a method for handling ready- mix concrete, the method comprising the steps of: rotating the ready-mix concrete in a drum of a concrete mixer, the drum being rotatable about its axis; measuring a yield stress value of the ready-mix concrete in the rotary drum; comparing the yield stress value to a threshold yield stress value of the ready-mix concrete; generating an output signal based on said comparison; handling the ready-mix concrete based on said output signal.

[0011] The expression "handling" is to be interpreted in a broad manner which is meant to encompass the terms "evaluating", "adjusting", "adding substances", "manipulating" and/or "pouring".

[0012] Many further features and combinations thereof concerning the present improvements will appear to those skilled in the art following a reading of the instant disclosure.

DESCRIPTION OF THE FIGURES

[0013] In the figures,

[0014] Fig. 1A is a graph of an example of the relation between strength and water content of the ready-mix concrete;

[0015] Fig. 1 B is a graph of an example of the relation between viscosity and water content of the ready-mix concrete;

[0016] Fig. 2 is a graph of an example of the relation between strength and viscosity;

[0017] Fig. 3 is a graph of an example of the relation between yield stress and viscosity which illustrates the effects of increasing and/or reducing substances in the ready-mix concrete;

[0018] Fig. 4 is a schematic side view of an exemplary concrete mixer;

[0019] Fig. 5 is a cross section of a drum of the concrete mixer of Fig. 4;

[0020] Fig. 6 is a flow chart of an example of a method for handling ready-mix concrete; [0021] Fig. 7 is a flow chart of an example of a method for comparing a viscosity value to a corresponding threshold viscosity value used for handling ready-mix concrete;

[0022] Fig. 8 is a graph of examples of slopes of pressure versus drum speed for measuring viscosity values associated with different ready-mix concrete samples;

[0023] Fig. 9 is a chart of an example of isometric curves for flow resistance (g) versus torque viscosity (h) for determining pumping pressure of the ready-mix concrete.

DETAILED DESCRIPTION

[0024] Handling ready-mix concrete can be challenging in various ways. For instance, composition of the ready-mix concrete prior to being poured in formworks can have an influence on structural properties of the concrete once it has hardened through a curing process. It is therefore useful to suitably monitor the composition of the ready-mix concrete in order to save costs and time. The compressive strength of the cured concrete is inversely proportional to the amount of water in the ready-mix concrete (see Fig. 1A) and the slump can be proportional to the amount of water. Consequently, the compressive strength of the cured concrete can be evaluated based on the slump in an inversely proportional manner. However, it has been found that when admixtures and/or other substances are provided in the ready-mix concrete, slump tests can err in estimating a compressive strength of the cured concrete since the slump can vary depending on the admixtures and/or the other substances.

[0025] It has been found that rheological properties, e.g. viscosity and yield stress, of the ready-mix concrete can be measured and used in the estimation of the compressive strength of the cured concrete. Indeed, the compressive strength of the cured concrete is inversely proportional to the amount of water in the ready-mix concrete (see Fig. 1A) and the viscosity is inversely proportional to the amount of water in the ready-mix concrete (see Fig. 1 B). Thus, the compressive strength of the cured concrete can be evaluated based on the viscosity in a proportional relationship (see Fig. 2). Therefore, in various embodiments, the methods and systems disclosed herein can be used to estimate the quality, e.g. the strength, of the cured concrete based on rheological properties of the ready-mix concrete. The method and system disclosed herein can also be used to adjust the amount of water, the amount of admixture, the amount of aggregate and/or the amount of cement which is to be added to the ready-mix concrete in order to obtain a suitable compressive strength after the curing process. To do so, suitable zones for each of the rheological properties may be determined in a calibration process. These suitable zones typically have a threshold value (lower limit) and a maximum value (upper limit) which are based on measured compressive strengths of samples of the cured concrete which were made from ready-mix concrete having known, varying rheological properties.

[0026] Fig. 3 is a graph of an example of the relation between yield stress and viscosity which illustrates the effects of increasing and/or reducing water content of the ready-mix concrete and of increasing superplasticizing (SP) admixture content of the ready-mix concrete. While Fig. 2 shows that adding an amount of water to the ready-mix concrete can have an impact on the strength of the cured concrete, it can also have an impact on the yield stress. Indeed, Fig. 3 shows that by adding an amount of water to the ready-mix concrete, the viscosity thereof and the resulting yield stress can be reduced. Inversely, by reducing the water-cement ratio (e.g., by adding aggregates), the viscosity as well as the resulting yield stress can be increased. However, it has been found that by adding some admixture, such as a SP admixture, the viscosity remains relatively unchanged while the yield stress can be controlled.

[0027] In one embodiment, the methods and device disclosed herein can be used concurrently with a concrete mixer 10 such as shown in Fig. 4. The concrete mixer 10 has a drum 12 which contains the steady-mix concrete 16. The drum is adapted to rotate around an axis 14 thereof for continuous mixing of the ready-mix concrete thereinside. Aggregates, admixtures and/or other substances can be added to the ready-mix concrete 16 of the drum 12 via a hopper 18. The hopper 18 is connected to the drum 12 of the concrete mixer 10 via an opening 20 which can be opened to allow the additional aggregates, for instance, to be mixed with the ready-mix concrete 16 thus increasing the viscosity of the ready-mix concrete 16. Water can be added to the ready-mix concrete 16 of the drum 12 via a water valve 22 operatively connected to a water reservoir 24. The water reservoir 24 is generally positioned above the center of the drum 12 for allowing water to drop in the drum 12 upon opening of the water valve 22. In some other embodiment, the water reservoir 24 can be located below the center of the drum 12 and be pumped with a pumping system (not shown), for instance. For measuring the rheological property values of the ready-mix concrete 16, a rheological value sensor 26 can be used. The rheological properties to be measured via the rheological property value sensor include at least viscosity of the ready-mix concrete and yield stress thereof. Fig. 5 is a cross sectional view of the rotating drum 12 taken along line 5-5 of Fig. 4. In the embodiment of Fig. 5, the rheological value sensor 26 is mounted inside the drum 12 via a mounting base 28. An example of the rheological value sensor 26 is described in the U.S. Patent Application having the Publication Number 2012/0204625 A1 , which is hereby incorporated by reference.

[0028] In the embodiment of Fig. 4, the concrete mixer 10 has a computing device 30 mounted thereto. The computing device 30 may comprise one or more data processors 32 (referred hereinafter as "processor 32") and one or more associated memories 34 (referred hereinafter as "memory 34"). The computing device 30 may comprise one or more digital computer(s) or other data processors and related accessories. The processor 32 may include suitably programmed or programmable logic circuits. The memory 34 may comprise any storage means (e.g. devices) suitable for retrievably storing machine-readable instructions executable by the processor 32. The memory 34 may comprise non-transitory computer readable medium. For example, the memory 34 may include erasable programmable read only memory (EEPROM) and/or flash memory. The memory 34 may comprise, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device. Such machine-readable instructions stored in the memory 34 can instruct the processor 32 to execute functions associated with various methods disclosed herein or part(s) thereof. The execution of such methods may result in the computing device 30 producing output. The computing device 30 can be mounted on the concrete mixer 10 or can be mounted elsewhere. For instance, rheological property values can be transmitted to an external computing device located at a remote location and which can process the measured values and then transmit back an output signal usable for handling the ready-mix concrete. The output may comprise data representative of one or more characteristics of the ready-mix concrete. The computing device 20 receives data indicative of rheological value measurements from the rheological value sensor 26 and can determine whether if water and/or aggregate should be added to the ready-mix concrete in accordance with the method disclosed herein. The computing device 30 can be operatively connected to the rheological value sensor 26, to the opening 20 of the hopper 18, and to the water valve 22 of the water reservoir 24. Therefore, the concrete mixer 10 can suitably control the constitution of the ready-mix concrete 16 in accordance with the methods disclosed herein.

[0029] Fig. 6 is a flowchart illustrating an exemplary method 600 for handling ready-mix concrete 16 in a drum 12 of a concrete mixer 10. In some embodiments, the method 600 may comprise: a step 602 of rotating the concrete ready-mix 16 in the drum 12 of the concrete mixer 10, wherein the drum 12 is rotatable about the axis 14; a step 604 of measuring a viscosity value of the ready-mix concrete in the rotary drum 12; a step 606 of comparing the measured viscosity value to a corresponding threshold viscosity value using the computing device 30, wherein the threshold viscosity value is determined based on a calibration process including a step 606a of obtaining a threshold viscosity value corresponding to a minimum expected strength of the ready-mix concrete when in a cured state and a step 606b of providing the threshold viscosity value to the computing device 30; a step 608 of generating an output signal based on said comparison; a step 610 of handling (pouring, adjusting, modifying) the concrete ready-mix based on the output signal; and a step 612 of obtaining a cured concrete having an expected compressive strength. More details on the calibration process are provided below.

[0030] The comparison step 606 is based on Figs. 2 and 3. Indeed, upon measurement of the viscosity of the ready-mix concrete 16, the resulting strength of the cured concrete can be determined. In most circumstances, a minimum compressive strength o*_min of the cured concrete will be calculated for a given application. To achieve a cured concrete having the minimum compressive strength o*_min, the viscosity value of the ready-mix concrete should equal at least a threshold viscosity value v_min of a viscosity zone 50 (as shown in Fig. 2). The viscosity zone 50 also has a maximum viscosity value v_max above which the ready-mix concrete is found to exhibit physical properties which cause pouring and/or pumping challenges. For instance, a ready-mix concrete having a viscosity value above than the maximum viscosity value v_max of the viscosity zone 50 may causes blockage or limit the pumping rates. [0031] When the viscosity value of the ready-mix concrete is measured with the rheological value sensor 26 and that the measured viscosity value is higher than the threshold viscosity value v_min of the viscosity zone 50, the computing device 30 can open the water valve 22 and release a predetermined amount of water inside the drum 12 of the concrete mixer 10, thus lowering the viscosity of the ready-mix concrete and adjusting the compressive strength of the cured concrete to the minimum compressive strength o*_min. Once this step is performed, the yield stress of the ready-mix concrete 16 is measured with the rheological value sensor 26 in order to determine if admixture and/or aggregate should be added to the ready-mix concrete. For instance, when the measured yield stress of the ready-mix concrete is higher than a threshold yield stress value o_mm of the yield stress zone 52 (see Fig. 3), SP admixture can be added to the ready-mix concrete which can lower the yield stress of the ready-mix concrete while maintaining the viscosity at the minimum viscosity value v_min, for instance.

[0032] Fig. 7 is a flowchart illustrating another exemplary method 700 for handling ready- mix concrete. The method comprises: a step 702 of measuring a viscosity value of the ready-mix concrete; a step 704 of comparing the measured viscosity value v_meas to the viscosity zone 50 having the threshold viscosity value v_min and a maximum viscosity value Vmax wherein a step 706 of adding an amount of aggregates and/or admixtures and/or cement is performed if v_meas < v_min and a step 708 of adding an amount of water based on the output signal until v_meas ~ v_min is performed when v_meas > v_min; once v_meas ~ v_min is reached, a step 710 of measuring a yield stress value of the ready-mix concrete is done. Then, the method 700 comprises a step 712 of comparing the measured yield stress value o_meas to a the yield stress zone 52 having the threshold yield stress value o_mm and a maximum yield stress value o_max; a step 714 of adding an amount of admixture based on the output signal until o_meas " <¾;„ when o_meas > <¾„; and a step of 716 of pouring the concrete ready-mix based on the output signal when o_meas " o_min is reached.

[0033] The calibration process is the method by which the suitable zones of the rheological properties are determined. For instance, the viscosity zone 50 and the yield stress zone 52 can be determined based on this calibration process. Such a process may include the steps of: providing a plurality of samples of ready-mix concrete, wherein the plurality of samples have varying, known viscosity values; a step of curing the plurality of samples of ready-mix concrete obtaining a plurality of cured samples; a step of measuring the compressive strength value of each one of the plurality of samples of cured samples; and a step of associating the compressive strength values to corresponding viscosity values to produce said calibration data. Then the calibration can be stored on the memory 34 of the computing device 30 (as in step 606b of method 600) or printed on a ready-mix concrete product for visual inspection by a skilled worker. In one embodiment of the present disclosure, a skilled worker may check calibration charts printed on a ready-mix concrete product for obtaining the minimum viscosity value v_min required to obtain a minimum compressive strength a*_min. Then, he/she can determine whether if some water or some aggregates should be added to the ready-mix concrete.

[0034] Fig. 8 is a graph showing exemplary curves of the pressure applied on the rheological value sensor 26 as the drum 12 of the concrete mixer 10 rotates around the axis 14 for different ready-mix concrete samples. Each linear regression is indicative of the rheological properties of the ready-mix concrete samples. For instance, the slope represents the viscosity value and the y-intercept is the yield pressure value of the ready-mix concrete. The results were obtained from ready-mix concrete yielding cured concrete having a compressive strength of 75 MPa after 30 minutes of curing, 1 hour of curing, 2.5 hours of curing and for one sample with water added therein. It can be seen that the curing time can influence the yield stress value (the y-intercept) while the viscosity value (the slope) remains unchanged. However, for a ready-mix concrete with water added therein, the viscosity value drops from -1.2 kPa/rpm to 0.304 kPa/rpm.

[0035] Table 1 , below, shows example compressive strengths of dehydrated and hydrated samples of cured concrete for different curing (or aging) times.

Before addition of water After addition of water

(days) Cube 1 Cube 2 Average Cube 3 Cube 4 Average

(MPa) (M Pa) (M Pa) (MPa) (MPa) (MPa)

3 58.5 57.0 57.8 48.5 50.0 49.2

7 67.5 64.5 66.0 56.0 55.0 55.5

28 81 .0 79.0 80.0 66.0 64.0 65.0

Table 1 : example compressive strengths of dehydrated and hydrated samples

[0036] For instance, it can be seen that the average compressive strength of sample cube 1 and sample cube 2 are respectively 57.8 MPa, 66.0 MPa and 80.0 MPa for 3 days, 7 days and 28 days of curing. However, for sample cube 3 and sample cube 4 made from ready-mix concrete having water added thereto, the average compressive strength drops to, respectively, 49.2 M Pa, 55.5 M Pa and 65.0 MPa. As described above, sample cubes having water added thereto exhibit a smaller viscosity and therefore, a smaller compressive strength.

[0037] Fig. 9 is a chart of an example of isometric curves for flow resistance (g) versus torque viscosity (h) for determining pumping pressure of the ready-mix concrete. The use of rheological properties to predict pumpability of the ready-mix concrete gives a suitable estimation of the required pumping pressure (for a pump with a constant flow). As shown in Fig. 9, an increase in the value of g or h produces an increase in the required pumping pressure. Also, the rheological properties (flow resistance and torque viscosity) are easier to obtain (faster and without operator influence) and more precise than slump measurements and pressure bleed tests. Accordingly, the viscosity zone 50 can have a maximum viscosity value v_max above which pumping challenges can occur. Therefore, the methods and system disclosed herein can be used to tune the ready-mix concrete using at least a viscosity measurement. For instance, if the viscosity value of the ready-mix concrete is comprised within the viscosity zone 50 (v_min < v_meas < v_max) and/or within the yield stress zone 52 (o_min < Omeas < &max) , the minimum compressive strength is likely to be achieved and the pumping challenges are likely to be avoided. [0038] The methods and system disclosed herein may be used in static concrete mixing and mobile concrete mixing applications. For example, the methods and system disclosed herein may be used in concrete mixers, concrete agitator trucks, as well as in wheelbarrows and tarps which can be provided with various pumping systems. The methods and system disclosed herein may be used in applications ranging from residential, commercial and industrial constructions sites. For instance, the methods and system disclosed herein may be used in the preparation of ready-mix concrete used for, but not limited to, sidewalks, highways, bridges, houses, dams and skyscrapers.

[0039] As can be understood, the examples described above and illustrated are intended to be exemplary only. For instance, the computerized operations such as computer- implemented comparisons and electronic signal generation can be performed by one or more computers or computer devices connected to the vehicle sensors and/or subsystems in a wired or wireless manner. In one example, one computer can be a smartphone adapted to receive signals from one or more sensors on the vehicle and to control subsystems of the vehicle in a wireless manner. In another example, the computer can be remote from the vehicle and the vehicle can communicate with the computer via the Internet. The scope is indicated by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A method for handling ready-mix concrete, the method comprising the steps of: rotating the ready-mix concrete in a drum of a concrete mixer, the drum being rotated about its axis; measuring a viscosity value of the ready-mix concrete in the drum; obtaining an electromagnetic signal stemming from a computer-implemented comparison between the measured viscosity value to a threshold viscosity value corresponding to a minimum expected strength of the ready-mix concrete when in a cured state; handling the ready-mix concrete based on said output signal.

2. The method of claim 1 , wherein the signal is indicative of said measured viscosity value exceeding the threshold viscosity value based, and said handling includes adding an amount of water upon obtaining the signal.

3. The method of claim 2, wherein said adding includes lowering the viscosity of the ready- mix concrete to the threshold viscosity value.

4. The method of claim 3, further comprising measuring a yield stress value of the ready- mix concrete in the rotary drum; obtaining an electromagnetic signal stemming from a computer-implemented comparison between comparing the measured yield stress value and a threshold yield stress value; and said handling includes adding an amount of admixture based on a determination that the viscosity corresponds to the threshold viscosity value and that the measured yield stress value exceeds the threshold yield stress value.

5. The method of claim 4 wherein said adding an amount of admixture includes lowering the yield stress of the ready-mix concrete to the threshold yield stress value.

6. The method of claim 4, wherein the admixture includes a superplasticizer.

7. The method of claim 1 , further comprising obtaining a signal stemming from a computer- implemented comparison of the measured viscosity value to a given maximum viscosity value; further comprising pouring the ready-mix concrete based on a determination that said measured viscosity value exceeds the threshold viscosity value and that said measured viscosity value does not exceed the given maximum viscosity value.

8. The method of claim 7, further comprising measuring a yield stress value of the ready- mix concrete in the rotary drum; obtaining a signal stemming from a computer- implemented comparison of the measured yield stress value to a threshold yield stress value; wherein said pouring the ready-mix concrete is further performed based on a determination that said measured yield stress value exceeds the threshold yield stress value.

9. A system for handling ready-mix concrete comprising: a concrete mixer having a drum for containing ready-mix concrete, the drum being rotatable about its axis; a rheological value sensor mounted in the drum of the concrete mixer and being adapted to measure at least one rheological property value of the ready-mix concrete inside the drum of the concrete mixer; and a computing device operatively connected to the rheological value sensor and being adapted to compare the measured at least one rheological property value to a corresponding threshold value, the computing device being further adapted to generate an output signal based on said comparison, and adapted to handle the ready-mix concrete based on said output signal.

10. The system of claim 9, wherein the at least one rheological property value includes a viscosity value.

11. The system of claim 10, the concrete mixer further comprises a water valve connecting a water reservoir to the drum of the concrete mixer, the computing device being adapted to control an opening of the water valve to add an amount of water in the drum of the concrete mixer upon determining that said measured viscosity value exceeds a threshold viscosity value corresponding to a minimum expected strength of the ready-mix concrete when in a cured state.

12. The system of claim 11 , wherein said amount of water is selected to lower the viscosity of the ready-mix concrete to the threshold viscosity value.

13. The system of claim 9, wherein the at least one Theological property value includes a yield stress value.

14. The system of claim 13, wherein the concrete mixer further comprises an input hopper connected to the drum of the concrete mixer, the computing device being adapted to control an opening of the input hopper to add an amount of admixture based on the output signal upon determining that said measured yield stress value exceeds a threshold yield stress value.

15. The system of claim 14, wherein the admixture includes a superplasticizer.

16. A method for the handling of ready-mix concrete, the method comprising the steps of: a computer obtaining a viscosity value of ready-mix concrete in a drum of a concrete mixer; the computer comparing the measured viscosity value to a threshold viscosity value corresponding to a minimum expected strength of the ready-mix concrete when in a cured state; and the computer generating an electromagnetic output signal based on said comparison.

17. The method of claim 16, further comprising the computer obtaining a yield stress value of the ready-mix concrete in the rotary drum; comparing the measured yield stress value to a threshold yield stress value; and the electromagnetic output signal is indicative that the viscosity corresponds to the threshold viscosity value and that the measured yield stress value exceeds the threshold yield stress value.

18. The method of claim 16, further comprising the computer comparing the measured viscosity value to a given maximum viscosity value; and the electromagnetic output signal is indicative that said measured viscosity value exceeds the threshold viscosity value and that said measured viscosity value does not exceed the given maximum viscosity value.

19. The method of claim 18, further comprising the computer obtaining a yield stress value of the ready-mix concrete in the rotary drum; comparing the measured yield stress value to a threshold yield stress value; and the electromagnetic output signal is indicative that said measured yield stress value exceeds the threshold yield stress value.

20. A method of producing calibration data, the method comprising the steps of: providing a plurality of samples of ready-mix concrete, the plurality of samples having varying, known viscosity values; curing the plurality of samples of ready-mix concrete obtaining a plurality of cured samples; measuring the compressive strength value of each one of the plurality of samples of cured samples; and associating the compressive strength values to corresponding viscosity values to produce said calibration data.

21. The method of claim 20 further comprising printing a calibration chart based on said calibration data on a concrete dry-mix product.

22. The method of claim 20, further comprising storing the calibration data on a computer readable-medium.

23. The method of claim 20, wherein the plurality of samples are made from a common ready-mix concrete to which a varying, known amount of water is added thereto.

24. The method of claim 20, further comprising at least one of adding an amount of water to the ready-mix concrete and adding an amount of admixture based on the calibration data and pouring the ready-mix concrete.

25. A method for handling ready-mix concrete, the method comprising the steps of: rotating the ready-mix concrete in a drum of a concrete mixer, the drum being rotated about its axis; measuring a yield stress value of the ready-mix concrete in the rotary drum; obtaining an electromagnetic signal stemming from a computer-implemented comparison between the measured the yield stress value and a threshold yield stress value of the ready-mix concrete; handling the ready-mix concrete based on said output signal.

26. The method of claim 25, further comprising measuring a viscosity value of the ready- mix concrete in the rotary drum; and adding an amount of admixture based on a determination that the measured viscosity value of the ready-mix concrete corresponds to a threshold viscosity value corresponding to a minimum expected strength of the ready- mix concrete when in a cured state and that the measured yield stress value exceeds the threshold yield stress value.

27. The method of claim 26 wherein said amount of admixture is selected to lower the yield stress of the ready-mix concrete to the threshold yield stress value.

28. A method for the handling of ready-mix concrete, the method comprising the steps of: a computer obtaining a yield stress value of ready-mix concrete in a drum of a concrete mixer; the computer the measured the yield stress value and a threshold yield stress value of the ready-mix concrete; and the computer generating an electromagnetic output signal based on said comparison.

29. The method of claim 28, further comprising the computer obtaining a viscosity value of the ready-mix concrete in the rotary drum; and the electromagnetic output signal being indicative that the measured viscosity value of the ready-mix concrete corresponds to a threshold viscosity value corresponding to a minimum expected strength of the ready-mix concrete when in a cured state and that the yield stress value exceeds the threshold yield stress value.

30. The method of claim 29 further comprising calculating an amount of admixture required to lower the yield stress of the ready-mix concrete to the threshold yield stress value.