Method of producing Nanoconcrete with High-Energy Mixing

Abstract

In a method of producing nanoconcrete according the bottom-up approach of nano technology with the High-Energy Mixing of composition including cement, water, sand, additives and superplasticizers, the mixing is performed with flow of mixture characterized by Reynolds number and Power number in the range of 20-800 and 0.1-4.0 respectively with installation a disk horizontally into mixing assembly on the top layer of activated mixture coaxially with vertical axis of assembly and with the axis of impeller rotation on the adjustable level to avoid destroying created gel as a result of interruptions of process, to increase laminarity of the mixture flow, energy absorption by the mixture, and shear stress for creation additional quantity of the nanostructured Calcium Silicate Hydrate (CSH) gel necessary for making nanoconcrete.

Claims

1. A method of producing nanoconcrete according to the bottom-up approach of nano technology with the High-Energy Mixing of composition of cement and water, the mixing is performed with a mixture flow characterized by dimensionless Reynolds number and Power number in the range of 20-800 and 0.1-4.0 respectively with installation a disk horizontally into mixing assembly on the top layer of activated mixture coaxially with vertical axis of assembly and with the axis of impeller rotation on the adjustable level, to avoid destroying created gel as a result of interruptions of High-Energy mixing, to increase laminarity of the mixture flow, energy absorption by the mixture, and shear stress for creation additional quantity of the nanostructured Calcium Silicate Hydrate (CSH) gel necessary for making nanoconcrete.

2. A method as defined in claim 1 wherein said composition of cement and water includes also sand, superplasticiser and shrinkage compensating additives.

3. A method as defined in claim 1 wherein said disk includes disk fabricated of flexible material or a metal lattice and having an opening at the center of it for circulation the top part of processed mixture pressed back above the disk.

4. A method as defined in claim 1 wherein said adjustable level of disk location includes at least one hanger attached to the disk to provide adjustments of its location during the High-Energy Mixing.

5. A method as defined in claim 1 wherein said High-Energy Mixing assembly further comprising forming this assembly including cylindrical container, impeller and disk as a small scale working prototype and a production scale High-Energy Mixing assembly, and monitoring a temperature of the mixture, power consumption and impeller rotation parameters with and without a mixture by a sensors and measuring devices, and inputting running values of said parameters, density of mixture and geometrical parameters of mixing assembly as constants and outputting running and average values of measured and calculated parameters including gross and net power consumption, apparent dynamic viscosity of a mixture and the dimensionless criteria Reynolds and Power numbers as well as interruptions of process if needed by a computer device.

6. A method as defined in claim 1 wherein said mixing assembly includes providing changing a volume of mixture by proportionally changing geometric parameters of the mixing assembly and installed disk while maintaining constant average values of gross and net specific power, Reynolds and Power numbers for each particular mixture.

7. A method as defined in claim 1 wherein said mixing assembly includes providing changing a volume of mixture in the same cylindrical container by moving up and down the disk according the level of mixture and proportionally increasing power of drive and height of the impeller blade.

8. A method as defined in claim 1 wherein said additional quantity of the nanostructured Calcium Silicate Hydrate (CSH) gel includes providing determination of the quantity of CSH gel in comparable cement containing mixtures with testing said mixtures during several days of hardening in conditions of the temperature below 8 C. and higher 23 C. by measuring the penetration resistance development after thawing when the temperature of mixtures increases to +5 C.

Description

BRIEF DESCRIPTION OF DRAWINGS AND TABLE

[0010] FIG. 1 High-Energy Mixing (HEM) with and without movable disk.

[0011] FIG. 2 Re number change in HEM of Cement-Water mixture without disk (test 1).

[0012] FIG. 3 Re number change in HEM of Cement-Water mixture with flexible disk (test 1).

[0013] FIG. 4 Penetration resistance at 15 C. of Cement-Water mixtures (test 1),

[0014] FIG. 5 Re number change in HEM of Cement-Water mixture without disk (test 2).

[0015] FIG. 6 Re number change in HEM of Cement-Water mixture with disk of lattice (test 2).

[0016] FIG. 7 Penetration resistance at 15 C. of Cement-Water mixtures (test 2),

[0017] FIG. 8 Re number change in HEM of Cement-Sand-Water mixture without disk (test 3).

[0018] FIG. 9 Re number change in HEM of Cement-Sand-Water mixture, with flexible disk (test 3).

[0019] FIG. 10 Penetration resistance at 15 C. of Cement-Sand-Water mixtures (test 3),

[0020] FIG. 11 Re number change in HEM of Cement-Sand-Water mixture without disk (test 4).

[0021] FIG. 12 Re number change in HEM of Cement-Sand-Water mixture with disk of lattice (test 4).

[0022] FIG. 13 Penetration resistance at 15 C. of Cement-Sand-Water mixtures (test 4).

TABLE-US-00001 TABLE 1 Improvement of technical parameters of the High-Energy mixing (HEM) process and C-S-H gel increase with introducing of the movable disk in mixing assembly. The main indexes of High-Energy Mixing Test Specific Average #, Cement/ Quantity Coefficient Energy Shear Test, Sand / Of Re/Np of Power Absorption Stress, K Fig. Water ratio Disk Interruptions average absorption KJ/kg N/m.sup.2 c-s-h 1, 1:0.0:0.37 No 0 826/ 0.516 50.6 1709 1.74 FIG. 2 0.159 1, 1:0.0:0.37 With 0 668/ 0.580 55.3 2370 3.63 FIG. 3 flexible 0.137 disk 2, 1:0.0:0.37 No 0 424/ 0.561 82.9 4119 1.22 FIG. 5 0.42 2, 1:0.0:0.37 Disk 0 276/ 0.605 86.7 6395 2.25 FIG. 6 of 0.55 metal lattice 3, 1:0.64:0.37 No 10 447/ 0.485 50.9 3002 2.8 FIG. 8 0.39 3, 1:0.64:0.37 With 0 178.7/ 0.60 63.46 5389 4.2 FIG. 9 Flexible 0.792 disk 4, 1:0.64:0.37 No 9 433/ 0.46 48.0 2643 4.4 FIG. 11 0.28 4, 1:0.64:0.37 Disk 0 197/ 0.577 56.57 4204 8.5 FIG. 12 of 0.468 Metal lattice

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] According to the present invention, a method for producing nanoconcrete in compliance with the bottom-up approach of nano technology, based on a High-Energy Mixing of a composition consisting at least of cement and water, mixing is performed with a mixture flow characterized by dimensionless criteria Reynolds number and Power number in the range of 20-800 and 0.1-4.0 respectively is proposed.

[0024] These criteria are taken as generalizing parameters that characterize the optimal flow of the mixture achieved in a working laboratory prototype of facility for the reproduction of the same flow on the production scale assembly.

[0025] The inventive method includes installation a disk horizontally into mixing assembly at the top layer of activated mixture coaxially with vertical axis of assembly and with the axis of impeller rotation on the adjustable level, to avoid destroying created gel as a result of interruptions of High-Energy Mixing, to increase laminarity of the mixture flow, energy absorption by the mixture, and shear stress for creation additional quantity of the nanostructured Calcium Silicate Hydrate (CSH) gel necessary for making Nanoconcrete.

[0026] The movable disk having the central hole located horizontally at the top layer of activated mixture (FIG. 1-B). Disk made of flexible material (FIG. 1-C) or metal lattice (FIG. 1-D) provides the possibility to limit the free volume of the mixture circulation. Without a disk it is spreading out inside the full volume of mixer (FIG. 1-A). The movable disk creates opportunity of increasing laminarity of the mixture flow characterized by the reduction of average value of Reynolds number, improving energy absorption by the mixture in order to increase Shear stress. The handles are attached to movable disk (FIG. 1-B) for making adjustments of its location to provide the optimal level of the Energy absorption and to avoid interruptions during the High-Energy Mixing process.

[0027] The inventive method comprise forming the activating assembly as a small scale working prototype of a production scale activating assembly, monitoring a temperature of the activated mixture, power consumption and impeller rotation parameters with and without mixture by a sensor and measuring devices, and inputting running values of said parameters as variables and geometrical parameters of the activating assembly namely L and D.sub.sheight and diameter of cylindrical surface formed when the impeller rotates, D.sub.cdiameter of container (FIG. 1-B) as constants and outputting running and average values of measured and calculated parameters including the temperature of activated mixture, net power consumption, apparent dynamic viscosity, shear stress and the dimensionless criteria Reynolds and Power numbers, by a computer device.

[0028] In activation with High-Energy Mixing according the present invention the main part of the activated mixture is located under a disk. The volume of circulating mixture increases in comparing with original one when impeller doesn't rotate and excess of it is moving up around flexible disk (FIG. 1-C) or disk made of metal lattice (FIG. 1-D) on the top of it and further through the central opening down to rotating impeller. All of this happens because vortex sucks excess of mixture back to main volume. This reduces the scattering of the mixture within the free volume of the mixer and the associated energy loss.

[0029] In the device of a disk suspension the opportunity of its displacement on vertical direction is provided. The viscosity of mixture changes during the process of HEM activation as a result of CSH gel formation. In some cases especially if the mixture contains sand the interruptions of the mixture circulation occurs and the power consumption fells down. The shift of the disk down allows to avoid interruptions of the process and restores the power consumption.

[0030] In the inventive method vertical adjustment of disk location is provided through hangers (FIG. 1-B,C,D) with the special mechanical device which should be created for production scale assembly. The results presented herein are getting on the small scale laboratory assembly with hangers operated manually.

[0031] The results of tests presented in graphs FIG. 2-FIG. 13 and in the Table 1 show that introducing of the disk into the mixer and installation it at the top layers of the mixture during High-Energy Mixing improve conditions of activation, namely allows to avoid interruptions of the process, increases laminarity of flaw (reduces Re number) of the activated mixture and as a result rises absorption of energy by the mixture and increases shear stress. All of this makes better conditions for creation additional quantity of nano structured CSH gel.

[0032] The special method based on determination the development of penetration resistance of mixtures at the temperature 15 C. created to get an approximate quantitative index of CSH gel increase to compare different variants of HEM activated mixtures with the control mixtures prepared without activation (see therein below, paragraph [0040]). The effectiveness of different methods of HEM activation was estimated with the coefficient of increase quantity of CSH gel in comparing with the control conventionally mixed variants. Coefficient K.sub.c-s-h was created and defined as the ratio of areas of the graphs Penetration Resistance in psiaging time at 15 C. in hours getting for activated and control mixtures (see FIG. 4, 7, 10, 13 and Table 1).

[0033] Development of penetration resistance at the temperature 15 C. of the CementWater mixture (W/C=0.37) after High-Energy Mixing with movable disk made of flexible material is 2 times more intensive in comparing with variant without disk (FIG. 4, test 1). Introducing the flexible disk in the top layer of activated mixture show reducing Re number (compare FIG. 2 and FIG. 3, test 1), increases of energy absorption and Shear stress (Table 1).

[0034] Analogous results are shown on FIG. 7, test 2, where the development of penetration resistance at the temperature 15 C. for the same mixture as in test 1 after HighEnergy Mixing with movable disk made of metal lattice was 1.84 times more intensive, than after activation without disc. Re number after this kind of disk implementation was reduced also (compare FIG. 5 and FIG. 6, test 2). The energy absorption and Shear stress increased also (Table 1).

[0035] Test 3 and test 4 are accomplished with the mixtures containing Cement, Sand and Water in proportions 1:0.64:0.37 respectively. This kind of mixture may be used also as HEM activated binder for Nanoconcrete.

[0036] The HEM activation of the Cement, Sand and Water mixture without movable disk show about 10 interruptions of process where Re number increases from 500 to 2500 (FIG. 8, test 3). With introducing a disk made of flexible material the interruptions are excluded and Re number reduced (FIG. 9, test 3 and Table 1). The index of penetration resistance development at temperature 15 C., K.sub.c-s-h increased 1.5 times in comparing activations with and without disk (FIG. 10, Table 1.).

[0037] FIG. 11, FIG. 12, (test 4) show Reynolds number change in HEM activation of the Cement-Sand-Water mixtures with disk made of metal lattice and without. About 9 interruption are observed in HEM activation without a disk, where Re number is changing from 500 to 2500. With the disk made of metal lattice there are no interruptions and Re number is reducing about 2 times, Shear stress increases 1.6 times (FIG. 12, Table 1). The Penetration resistance development of HEM activated mixtures shown on FIG. 13, test 4 used for calculation K.sub.c-s-h for variants with and without disk. Increase of nano structured CSH gel is almost 2 times as a result of metal lattice disk usage.

[0038] In the present invention the average value of Reynolds number significantly reduced by using disc made of an elastic material or a metal lattice, i.e. turbulence decreases and laminar flow of the mixture increases during the process of High-Energy mixing. This corresponds to an increase in the absorption of energy by a mixture consisting only of cement and water, and also containing sand. As a result the shear stress between the particles of the mixture significantly increases (see Table 1). This indicates an improvement in activation efficiency because of greater localization of the circulating mixture in comparing with activation without disk where the mixture is scattered throughout the full volume of the mixer (FIG. 1-A). As a result, conditions are created for a significant increase in the index of extension the relative content of nano-structured CSH gel (Table. 1).

[0039] In the inventive method it is possible to provide changing a volume of activated mixture by proportionally changing geometric parameters of the activating assembly while maintaining constant average values of net specific power and Reynolds and Power numbers for each particular task and mixture.

[0040] In the inventive method it is possible also to provide occurring at production small changes in the volume of the mixture activated with HEM by moving up and down the disk made of flexible material or the metal lattice inside the same cylindrical container designed for required maximal volume.

[0041] State of water in the volume of CSH gel increased as a result of High-Energy Mixing according the inventive method can be present within the interlayer structure as H.sub.2O or OH. The capillary pores 10-50 nanometers in diameter and larger than 3-5 micrometers outside and between CSH clusters can contain free water, solution so called bulk water. According R. A. Olson at al. (Interpretation of the impedance spectroscopy of cement paste via computer modeling, Part III Microstructural analysis of frozen cement paste, Journal of materials science 30, 1995, p. 5081 [9]) the calorimetric results of hardened cement paste show three well-defined peaks at approximately 8, 23, and 40 C. The peak at 8 C. is due to freezing bulk water in macro pores. The peak at 23 C. corresponds to the freezing of the smaller capillary pores of CSH gel, while the rather broad peak at 40 C. represents the low temperature transition of supersaturated solution in gel pores. Very little additional freezing occurs below this last peak.

[0042] Taking into account the results of the Mr. Olson research shown here above in order to evaluate the main result obtained from the application of the present invention, in the inventive process an approximate quantitative method of comparing mixtures with different amounts of CSH gel was created and used (see therein above). The method is based on the determination of Penetration Resistance development of the cement containing mixtures hardening at temperature 15 C. during several days. At these conditions the liquid phase in nano-sized pores of CSH gel doesn't freeze and able to interact with cement increasing the Penetration Resistance. The index of penetration resistance is determined every day after thawing of samples when the mixture temperature increases from 15 C. to +5 C. This non standardized method was broadly used in this invention for approximate estimation of the quantity of CSH gel increase after the inventive method of High-Energy Mixing in comparison with already known method (Method of producing activated construction mixture, the application Ser. No. 13/476,003 published Nov. 21, 2013, as invention No: 2013/0395963A1 [8]) and conventionally mixed control variant. For this purpose the coefficient (K.sub.c-s-h) was created and used. K.sub.c-s-h is defined as the ratio of the areas of the graphs Penetration Resistance in psiaging time at 15 C. in hours (see FIG. 4, 7, 10, 13 and Table 1).

[0043] Water in nano pores of CSH gel has a greater density i.e. smaller specific volume than ordinary water, filling micro and macro pores and capillaries in hardening cement paste. This can cause chemical shrinkage, which in ordinary concrete is small and does not create large internal stresses (J. Thomas, H. Jennings The Science of Concrete 2108, 5.3.1.1., p. 50 [6A]). In the case of nanoconcrete, where the volume of gel can be increased several times the risk of chemical shrinkage increases, which may cause the necessity of adding shrinkage compensating additives. This is provided by current invention.

The Physical Basis of the High-Energy Mixing (HEM) Process

[0044] The necessity to control the flow of the mixture developing in the mixer and effectiveness of energy usage requires considering additional parameters to calculate Reynolds and Power numbers. This also allows transferring the technological process fulfilled on the small scale activator to big production scale machine keeping the same levels of these criteria. It requires to consider some groups of parameters: geometrical parameters such as diameter of impeller rotationDs (m), height of bladeL (m), diameter of containerDc (m) and height of mixture in container before mixing-activationH (m), see FIG. 1; physical parameters such as net power of activationP (Watt) and total power inputP (Watt), net energy of activationE and total input of energy E (joules), as well as velocity of impellerN (Rpm and Rps).

[0045] Physical parameters values of the turned on empty activator labeled here as X.sub.0, the current values of them taken in the process of activation are labeled as X.sub.t. The present invention is based on experiments with variations of these parameters during the activation of construction mixtures shown therein above prepared with variety of impellers and their rotational speed.

[0046] Formulas for above mentioned dimensionless criteria to control their flow during the activation are the formulas for stirred vessel (P. K. Biswas, K. M. Godiwalla, D. Sanyal, S. C. Dev A simple technique for measurement of apparent viscosity of slurries: sand-water system, Materials & Design, India Elsevier Science Ltd. Vol. 23, 2002, p. 511-519, see p. 512, right column, [10]):

Re=(N.sub.tD.sub.s.sup.2)/(1)

Np=P/(N.sub.t.sup.3D.sub.s.sup.5) (2)

where is a density of the mixture in kg per cu. m, N.sub.t is a speed of impeller in Rps (revolutions per second), D.sub.sdiameter of impeller in m, apparent dynamic viscosity in Pas (Pascal-second), Pnet power in watt.

[0047] In the present invention the mixer-activator considered as a kind of rotational viscometer. It creates a possibility to use equations (1), (2) and (5) from (E. Freire et al. Process ability of PVDF/PMMA blends studied by torque rheometry, Materials Science and Engineering C 29, pp. 657-661, Elsevier 2009 [11]), to calculate the apparent dynamic viscosity () values in Pas through shear stress and shear rate determined with formulas (see p.p. 658,659) transformed for conditions of High-Energy mixing:

=/, (3)

Where is shear stress in N/m2, is shear rate in sec.sup.1.

=torque/(2R.sub.s.sup.2L), (4)

=(2(2(2N.sub.t)R.sub.c.sup.2)/(R.sub.c.sup.2R.sub.s.sup.2) (5)

[0048] Thus all these values may be calculated having the geometrical parameters of activator (R.sub.c, R.sub.s and L) mentioned above (see FIG. 1) as well as the data of rotation velocity (N.sub.t), net torque: T=P.sub.t/(2N.sub.t)P.sub.0/(2N.sub.0) and net Power: P=P.sub.tP.sub.o measured during the process of activation with HEM.

[0049] The equation for dynamic viscosity is valid for rotational viscometers with the rotated cylinder or blades immersed into liquid. In the present invention the main apparatus consists of the cylindrical container and impeller with straight or skewed blades (FIG. 1-B). The calculated dynamic viscosity () named as apparent dynamic viscosity of the mixture in the process of activation is a result of inertial forces action, developing into mixture, and consequently may be used as a denominator in the formula of Reynolds number. By adjusting the position of the disk flexible or made of metal lattice, it is possible to influence internal inertial forces. This changes the apparent dynamic viscosity and, consequently, the Reynolds number, Power number, specific absorbed energy and shear stress (see the sample of calculation of these parameters in Method of producing activated construction mixture, U.S. patent application Ser. No. 13/476,003 publication No US 2013/0305963, 2013, Table 2, page 5-6 [8].

[0050] In the inventive method further comprising forming the activating assembly as a small scale working prototype and/or a production scale activating assembly, monitoring a temperature of the activated mixture, power consumption and impeller rotation parameters with and without a mixture by a sensor and measuring devices; and inputting running values of said parameters as variables and geometrical parameters of the activating assembly and density of mixture as constants and outputting running and average values of measured and calculated parameters including gross and net power consumption, shear stress, apparent dynamic viscosity, and the dimensionless criteria Reynolds and Power numbers as well as interruptions of process and temperature of the mixture are fulfilled by a computer device.

[0051] The expected rotational velocity of the production scale mixer loaded with mixture, N (Rps) calculated as average from the conditions:

1-st, Re.sub.small scale mixer=Re.sub.production scale mixer;

2-nd, N.sub.small scale mixer=N.sub.production scale mixer.

The expected velocity of impeller for the empty production scale mixer should be increased by multiplying this calculated value on the ratio N.sub.empty/N.sub.loaded known for the small scale mixer.

[0052] In the inventive method calculation of production scale High-Energy mixer comprising proportionally changing a volume of small scale working prototype and other geometric parameters named here above while maintaining equals for small and production scale of mixing assembly maximal and average values of gross and net specific power and average values of Reynolds and Power numbers in order to correctly choose drive and geometry of the production scale mixer for each particular task and mixture. See the example of the results of calculation of the production scale the High-Energy mixer in Method of producing activated construction mixture, U.S. Patent application Ser. No. 13/476,003 publication No US 2013/0305963, 2013, Table 3, page 6 [8].

[0053] It will be clear that changes in the details, materials, steps and arrangement of parts which have been described and illustrated to explain the nature of the present invention as well as eliminating some of claimed parameters of invented process may be made by those skilled in the art upon reading of this disclosure with attaining considerable increase of CSH gel and other shown above changes of properties of the High-Energy Mixed mixture and in spite of it continue to stay within the principles and scope of present invention.

[0054] It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of method differing from the type described above.

[0055] While the invention has been illustrated and described as embodied in a method for producing nanoconcrete with the High-Energy Mixing, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

[0056] Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the stand point of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.