WO2020132721A1

WO2020132721A1 - Mixture of fines, fresh or hardened concrete, process for mixing and homogenizing said mixture of fines and process for producing said fresh concrete

Info

Publication number: WO2020132721A1
Application number: PCT/BR2018/050486
Authority: WO
Inventors: Mariana Figueira Lacerda De MENEZES; Victor Keniti SAKANO; Rafael Giuliano Pileggi; Markus Samuel REBMANN; Roberto Cesar de Oliveira ROMANO; Vanderley Moacyr JOHN; Seiiti SUZUKI; Fábio Alonso CARDOSO; Carlos José MASSUCATO; Marco QUATTRONE
Original assignee: Intercement Brasil S.A.; Universidade De São Paulo - Usp
Priority date: 2018-12-28
Filing date: 2018-12-28
Publication date: 2020-07-02
Also published as: AR115434A1

Abstract

The present invention relates to the more efficient use of concrete in order to mitigate CO2 emissions from the concrete/cement chain. The present invention discloses a mixture of fines, comprising a Portland cement and a first filler or a second filler or a mixture thereof. The Portland cement comprises a proportion of 50-90% of the mixture, preferably of 60-80%, and more preferably still, the proportion of Portland cement in the mixture is 65-75%. One or both of the fillers comprise a proportion of 10-50% of the mixture, said proportion preferably being 20-40%, and more preferably still, the proportion of one or both of the fillers in the mixture is 25-35%. The filler of the present invention is an inorganic material obtained by grinding or particle-size sorting the raw material thereof. The first filler has a BET surface area of less than or equal to 6 m2/g and particle-size distribution with an average area defined by the range 4 µm < d98 < 40 µm, and a second filler has a BET surface area of less than or equal to 2.3 m2/g and particle size distribution of average area of 6 µm < d85 < 40 µm. The packing porosity of the mixture is at least 0.5 percent less than the packing porosity of the Portland cement used in the present mixture. The present invention also relates to concrete prepared from said mixture, the process for preparing said mixture and said concrete.

Description

MIXING FINE, FRESH OR HARD CONCRETE, MIXING PROCESS AND HOMOGENEIZATION OF THE MIXTURE OF FINE AND PRODUCTION PROCESS OF THE DONE FRESH CONCRETE

FIELD OF THE INVENTION

[001] The present invention belongs to the field of the use of inorganic materials specially adapted to improve properties of cementitious materials. More specifically, the present invention deals with the more efficient use of binders in cementitious materials, such as concrete, in order to mitigate C0 ₂ emissions in the concrete / cement chain.

[002] The objectives of the present invention are achieved with the characteristics of packaging and mobility of particles that provide rheological behavior suitable for the application with reduction of C0 ₂ emissions and with the decrease in the water content of the mixture.

[003] Even more specifically, the present invention deals with a mixture of fines composed of a Portland cement and a filler; a fresh or hardened concrete composed of said mixture; a process of mixing and homogenizing said mixture of fines and a process of producing said fresh concrete.

BACKGROUND OF THE INVENTION

[004] The cement industry is responsible for approximately 5 to 8% of the world's anthropogenic emissions of greenhouse gases. Thus, reducing the environmental impact while increasing cement production is a necessity for the cement industry.

[005] The main emission reduction strategies are: replacement of clinker by supplementary cementitious materials, increased efficiency of kilns and use of alternative fuels, these, however, have limitations to achieve the objective of the ceiling scenario of increasing the temperature of the planet at 2 ° C. [006] An interesting alternative for reducing the carbon footprint of concrete is to increase efficiency in the use of binder in concrete, that is, to achieve better properties with less cement consumption. In addition, as cement represents the most significant fraction of the cost of concrete, increasing the efficiency of concrete also allows for cost savings.

Ligand intensity

[007] 1,584 literature and market data on concretes from 29 countries were collected, calculating the intensity of binder (IL) and each concrete (Eq. 1):

IL = ^l / _rc (Eq. 1)

Where :

IL = Binder intensity, in kg / m ³ / MPa

I = total amount of binder, in kg / m ³ ,

rc = performance requirement, compressive strength at 28 days (MPa).

[008] It was found that for concrete with compressive strength at 28 days of 30 MPa, the minimum IL is 8 kg / m ³ / MPa, usually due to the use of pure cements, however, the average is 12 kg / m ³ / MPa. The mere replacement of clinker in cement does not necessarily reduce the carbon intensity, some concretes with pure cement exhibit lower carbon intensity than with high clinker substitution. Thus, it was found that there is a need in the state of the art to increase the efficiency of concretes, with environmental and economic benefits.

[009] In order to achieve better concrete efficiency, the present invention uses the concepts of packaging and mobility.

Packing of particles

[010] The compactness or density of packaging

(Eq. 2) is the proportion of solids contained in a certain total volume. The porosity (Eq. 4) of the packaging is its complement, that is, the amount of voids in a certain total volume. The apparent volume (Eq. 3) is the inverse of the packing density.

Vsol

Pemp (Eq. 2)

Vtot

Pemp = packing density

V _S oi = Volume of solids

V _tot ⁼ Total volume

V _a p (Eq. 3)

Pemp

V _ap = Apparent volume and 1 Pemp (Eq. 4)

e = porosity

[011] There are two packaging possibilities: bimodal distribution and polimodal distribution. In the bimodal distribution there are more voids, while in the polimodal distribution, there are less voids.

[012] The porosity of the packaging of the system basically depends on three factors: the grain size curve, the morphology of the grains and the compaction method.

[013] The Westman and Hugill model (WESTMAN, AER; HUGILL, HR The packing of particles. Journal of the American Ceramic Society, [sl], v.13, n.10, p. 767-779, 1930) uses the concept of dominant fraction. The finer particles than the dominant fraction settle in their voids and do not increase the volume occupied by the mixture. The thicker ones, in turn, add only their volume of solids to the apparent volume. The model is shown in Eq. 5.

Where :

a _L = apparent volume of a discrete distribution of the size range i, with i ranging from 1 to n, with i = 1 being the thickest range and not the total range of mixtures;

Xj = volumetric fraction of size class i V _ai ⁼ apparent volume with reference to class i

[014] As a priori, it is not known which is the dominant fraction, in the present invention the apparent volume was calculated for all cases and, due to the impenetrability constraint (the apparent volume of the mixture is always greater than or equal to that of the pure dominant fraction ), the actual apparent volume is the highest value obtained.

Mobility

[015] The separation distance between particles is defined as: "average distance between any two adjacent particles in the mixture, assuming that all particles are separate entities, that is, that there are no clusters".

[016] A model for calculating this distance in suspensions, called IPS (Interpaticle Separation Distance), is described by Eq. 6 (FUNK, JE; DINGER, D. Predictive Process Control of Crowded Particulate Suspensions Applied to Ceramic Manufacturing. L.ed Clemson: Springer Verlag, 1994).

IPS = 2 / VSA [l / Vsol- (l / (l-))] (Eq. 6) where:

IPS = separation distance between particles (pm);

VSA = volumetric surface area (m ² / (cm ³ ));

Vsol = volumetric fraction of fine solids;

e = porosity of the fines packaging.

VSA = SSA p_sol (Eq. 7)

Where :

SSA = specific surface area (m ² / g) and

p_sol = density of the solid (g / m ³ )

[017] The IPS affects the rheological behavior of the suspension, as water needs to cover the surface of the particles, fill in the voids and space the particles. This space between the particles is what will allow the suspension concentrated flow. Thus, it is noted that the higher the IPS, the lower the viscosity of the suspension.

[018] The IPS shows that the factors that affect the rheological behavior include the particle size distribution, that is, the volume fraction of solids and the fraction of pores in the system, as well as the particle morphology, reflected in the volumetric surface area and the volume of water.

[019] The lower the porosity of the packaging, the greater the IPS and, therefore, the lower its resistance to movement. And yet, the more porous the particles, representing a larger volumetric surface area, the lower the IPS and the higher its viscosity.

[020] It is noteworthy that the IPS is evaluated in volume, although the materials are quantified in mass. This is because the packaging study is a spatial problem and the masses alone are not relevant, because what impacts the porosity properties of the packaging are the volumes.

[021] In a concrete, the IPS is applied to the paste, in which the particles are fine and the fluid that drives them away is water. In this context, the predominant forces are the superficial ones. However, in concrete, in addition to the suspension (which is its matrix), there are also aggregates. In this context, the most relevant forces are masses. Thus, the diameter of 100 pm is defined as the boundary between fine and coarse particles, since in this diameter is the transition region between the predominance of each type of force: superficial and mass.

Surface area - BET

[022] The surface of a real particle is not smooth, it contains pores, which influence its interaction with the medium, for example, with water in a concentrated suspension. The study of the surface of a particle is done through the analysis of the isothermal process of gas adsorption on the surface, analyzing the variation of the volume as a function of the partial pressure of the gas. [023] For sands, the assumption is made that the form factor of the entire sample is the same. Thus, the fines form factor is calculated based on the specific surface area and the granulometric curve and, considering this factor for all fractions, the specific surface area of the sand is determined.

Specific mass - Pycnometry

[024] Helium gas pycnometry determines the specific mass of a sample by comparing the pressure exerted by Helium gas in a closed container with the sample and another reference. Thus, the actual volume of the sample is determined, considering that there are no closed pores in the particles. Weighing the sample, the specific mass is calculated.

Particle size distribution

[025] Laser granulometry determines the granulometric distribution of fine materials, below the order of 355 pm. The principle of the technique is to launch a laser beam into the sample and measure the angular variation of the light that diffracts in the particles. Based on Mie's diffusion theory, it is possible to correlate the dispersion pattern of the sample with the diameter of its particles.

Dynamic Image Analysis (AID)

[026] Dynamic image analysis is done by moving the sample in front of digital camera lenses that capture your images projected by a light source. The movement can be generated by gravity or flow of a carrier fluid. As digital cameras have a high frequency of image capture, it is possible to obtain several images of the same particle, in different positions. So, although each image is captured in 2D, it is possible to make a projection of the third dimension based on the various images of the particle. Image processing is carried out to discard blurred images and overlays. This analysis allows the calculation of geometric parameters and sample size distribution.

[027] In addition to the size distribution, it is possible to calculate the theoretical volumetric area, based on this diameter. With this result, it is possible to calculate the Form Factor, a relationship between the specific BET area and the theoretical volumetric area. This factor indicates how far the actual surface area of the particles is from the theoretical sphere area.

[028] In the present invention, the following characterizations were performed:

_• Aggregates

- Dynamic Image Analysis: for Brita 1 and other aggregates;

- Pycnometry;

- BET for small and thin coarse aggregates.

_• Thin

- Laser granulometry;

- Pycnometry;

- BET

Paste and concrete rheometry

[029] The purpose of rheometry is to correlate the stress with the shear rate in the concrete. The rotational rheometry test uses a device with plate-plate geometry in the paste rheometer and in the concrete rheometer, the same being coupled to the planetary axis in the concrete rheometer.

TECHNICAL STATUS

[030] Usually, in concrete dosing by the conventional method, the aim is to reduce fines (particles smaller than 100 pm) in the formulation of concrete. The concept is that these fines have a very high specific surface area, compared to aggregates and, therefore, demand a larger volume of water to cover their particles and, thus, damage the concrete workability. However, research and development work, which resulted in the present invention, showed that this is only part of the problem.

[031] The packaging of fines is an important factor in this analysis. As shown by the IPS formula, mobility depends, in addition to the specific surface area, on the packaging of the particles. That is, in the R&D of the present invention, the particle size distribution of the filler was chosen in order to reduce the porosity of the packaging of the fines and guarantee an increase in mobility, which is reflected in the reduction of the demand for additives or reduction of the demand for water and gain of resistance.

[032] The R&D results of the present invention were unexpected, considering the conventional dosing logic, which was created based on the use of fillers with particle sizes that did not significantly reduce the porosity of the fines packaging and, thus, the impact negative of the specific area overlapped.

[033] With regard to patent literature, US 8246739 discloses a composition of clinker, plaster and a supplementary material, this supplementary material being defined by D90 <200pm. This definition of supplementary material is generic and encompasses all composite cements, that is, clinker composition, plaster and supplementary material, currently commercialized.

[034] On the other hand, it was observed in the examples of supplementary materials presented in that patent, that all consist of materials with d98> 70pm (as shown in Figure 2 of the American patent document). Thus, supplementary materials with d98 <70pm were not evaluated by the authors, who do not mention at any time, the optimal range with the unexpected effects achieved with the present invention. The invention of the aforementioned American patent focuses on the granulometry of Portland clinker with a Dv97 of 10 to 30 pm or with a specific Blaine surface greater than or equal to 5300 cm ² / g. That is, a vital characteristic of the American patent is the characteristic of clinker. Usually, Portland clinker is thicker than this range, with d97> 30pm. The advantage of adjusting the grain size curve of the filler and not of the clinker is the control of the specific area. As clinker is a reactive material, its specific area significantly increases when it comes in contact with water, however, this effect is much less with the filler. Thus, using the thin filer it is possible to increase mobility through the planned packaging porosity and the low specific surface area, which advantageously reduces the demand for additives, water and increases the efficiency of binders.

[035] US patent document 2012/0012034 discloses the use of a cement with a narrower grain size curve than that of conventional Portland cement. This curve of this American document was obtained in all examples through the sieving of conventional Portland cement and comminution of the retained particles - defined by d90 <25pm and d90 / dl0 <17.5, with the highest d90 mentioned being less than 30 pm. That is, the main feature of this patent document, as well as the US patent 8246739, is the characteristic of clinker. Usually Portland clinker is thicker than this range with d97> 30pm. The present invention uses conventional Portland cement and the examples have cements with d90> 30pm. The advantage of adjusting the filler and not the cement is due to the fact that the clinker is a reactive material, its specific area increases significantly when it comes into contact with water, this effect is much less with the filler.

[036] American patent US 9238591 also mentions an invention composed of a cement with narrow particle size range. The document mentions a fraction of cementitious supplementary material with an average diameter larger than cement, a fraction that the present invention does not contemplate. This patent uses the concept of particle packaging of the paste. It is important to mention that, in the present invention, the concept of porosity of packaging is different, as this is a characteristic that refers only to the particles of the mixture, whereas in US patent 9238591 the reference is on the set of particles plus water. These two concepts are different and cannot be compared in any way.

[037] The Brazilian patent document PI0711469 necessarily reveals the use in the composition of the mixture of a material of ultrafine granulometric class with d90 <lpm and specific surface area BET> 6m ² / g. The production of this material, being ultrafine, demands a high comminution energy, as well as specific equipment, in general, with low productivity and, in many cases, a wet grinding process, which requires a drying operation of the material after grinding. Process residues with this specification can be found, but their availability is limited and their value is high. That said, it is noted that the material revealed in the Brazilian document is more complex and noble than the material of the present invention. In this way, the filler of the present invention advantageously has a coarse particle size that requires less energy to obtain it. That is, the present invention presents balanced granulometry in order to maximize the properties of the cement.

[038] Patent document WO 93/21122 discloses a mixture consisting of a carbonate material with particle d50 <14pm. This specification defines only half the mass of the material, the fraction of 50% below 14 pm. It is known that, depending on the material properties, type of comminution equipment, separation technology and process adjustments, the granulometric curve of the output material can vary widely. Thus, for the present invention it is vitally important to ensure that 98% of the material is below the limit diameter, so that the packaging phenomenon presented certainly occurs. In the patent document WO 93/21122 it is shown in its example (Table 10), the use of the same amount of additive for both mixtures, not achieving the reduction in the demand for additives advantageously obtained by the present invention.

[039] In all the patent documents analyzed, it was not presented, observed, nor quantified the reduction in the demand for additives resulting from the use of supplementary cement materials pure or mixed with cement, as presented in the present invention.

[040] No patent document of the state of the art mentions the viscosity of the concretes in these formulations. It is important to note that the single-point test (such as the reduction of the cone trunk) is inappropriate for complex fluids (such as these concretes) because their responses to different shear rates are different. A single point test is only satisfactory for a Newtonian fluid that has a behavior described by a linear function passing through the origin. As concrete normally has a shear stress, it is impossible to describe it with just one test point. The behavior of the concrete described as heavy, cohesive, with pumping difficulties and coarse bubbles in the removal in the form (possible when these formulations are poorly dosed) is correlated with viscosity.

SUMMARY OF THE INVENTION

[041] The present invention discloses a mixture of fines, comprising a Portland cement and a first filler or a second filler or a mixture thereof.

[042] Portland cement comprises a fraction of 50 to 90% of the mixture.

[043] Said cement is any Portland cement defined according to the European standard, such as: a fraction of clinker plus calcium sulfate from 5 to 100% of the cement and, alternatively, a fraction of granulated blast furnace slag from 0 to 95% of cement, a fraction of pozzolanic material from 0 to 55% of cement, a fraction of carbonate material from 0 to 35% of cement, a fraction of cooked shale from 0 to 35% of Portland cement.

[044] One or both fillets comprise a fraction of 10 to 50% of the mixture.

[045] The filer of the present invention is an inorganic material from the grinding of its raw material or obtained by granulometric classification of its raw material, said raw material, including but not limited to, limestone or quartz or silica or cristobalite or nepheline or dolomite or granite or dust from the oven dust removal system or slag or fly ash or pozzolans or concrete waste or construction and demolition waste or a mixture of these.

[046] The first filer has a BET surface area less than or equal to 6 m ² / g and has a granulometric distribution with an average area defined by the range of 4pm <d98 <40pm, and a second filer has a BET surface area less than or equal to 2.3 m ² / g and a granulometric distribution of an average area of 6pm <d85 <40pm.

[047] In either of the two combinations of surface area and granulometry, the porosity of the packaging of the mixture must be at least 0.5 percentage point less than the porosity of the packaging of Portland cement used in this mixture.

[048] The present invention also has as its object a fresh or hardened concrete composed of said mixture, in which:

- the amount of the mixture is 200 to 500 kg / m ³ ;

- the amount of water is less than 180 l / m ³ ;

- incorporated air content is 0.5 to 5%; - the small aggregates have a particle size distribution with an average area of dlO> 90pm and d90 <5mm: from 500 to 1200 kg / m ³ ;

- coarse aggregates have a granulometric distribution with an average area characterized by dlO> 5mm: from 600 to 1400 kg / m ³ ;

- chemical additives for concrete, including, but not limited to: water reducing additive, air incorporating agent, viscosity reducing agent, setting accelerator or retarder, resistance accelerator or retarder: dosed between 0.3% and 5% of the mass of said mixture.

[049] The invention also has as its scope a process of mixing and homogenizing said mixture of fines in which, the elements of said mixture are mixed in a particle mixer in one unit, the said unit receiving, mixing, homogeneity and dispatches said mixture of fines. The mixing and homogenization of fines can also occur at the exit of the grinding of one of the constituents through a dosing scale and feeding to the flow of ground materials.

[050] The invention also teaches a production process of the said fresh or hardened concrete in which the production is carried out in a concrete batching or mixing plant, in which Portland cement, one or both fillers of said mixture, are received mixed or separately, both Portland cement and one or both fillers are dosed, mixed and homogenized with the other materials.

BRIEF DESCRIPTION OF THE FIGURES

[051] Figure 1 shows the discrete grain size curve of the fillers of the present invention.

[052] Figure 2 shows the accumulated grain size curve of the fillers. [053] Figure 3 shows the deflocculation curve of pure materials (yield stress as a function of additive content).

[054] Figure 4 shows the deflocculation curve of pure materials (apparent viscosity depending on the additive content).

[055] Figure 5 shows the deflocculation curve of pure materials (hysteresis area depending on the additive content).

[056] Figure 6 shows the change in yield strength (Figure 6a), apparent viscosity (Figure 6b) and hysteresis area (Figure 6c) as a function of the variation in Filer 2 content (replacement filer) for different levels of Water.

[057] Figure 7 shows the demand for additive according to the Filer 2 content.

[058] Figure 8 shows the change in yield stress (Figure 8a), apparent viscosity (Figure 8b) and hysteresis area (Figure 8c) depending on the variation of the replacement filer ratio (Filer 2) and performance (Filer 1) .

[059] Figure 9 shows the apparent viscosity of the mixtures as a function of the porosity of the fines packaging.

[060] Figure 10 shows the additive content as a function of the flow torque of Filer 1 in the concrete.

[061] Figure 11 shows the deflocculation curve of the concretes, apparent viscosity as a function of the additive content.

[062] Figure 12 shows the additive content (by weight of the fines) necessary to reach the apparent viscosity of 0.025 N.m / RPM as a function of the Filer 1 content.

[063] Figure 13 shows the relative expansion by aggregated alkali reaction, depending on the filer content.

[064] Figure 14 shows the retraction in 28 days, depending on the Filer 2 content of the mixture, for two different volumes of paste. [065] Figure 15 shows the torque curve per rotation of the concretes.

DETAILED DESCRIPTION OF THE INVENTION

Mixture

[066] The present invention reveals a mixture of fines, comprising a Portland cement according to the European standard and a first filer, here also called Filer 1 and a second filer, here also called Filer 2. Filer 1 can also be called filler filer, Filer 2, replacement filer.

[067] Portland cement comprises a fraction of 50 to 90% of the mixture, preferably 60 to 80%, with an even more preferable fraction of 65 to 75% of Portland cement in the mixture.

[068] Said cement is any Portland cement defined according to the present or future European standard, such as: a fraction of clinker plus calcium sulfate from 5 to 100% of the cement and, alternatively, a fraction of high granulated slag - furnace from 0 to 95% of cement, a fraction of pozzolanic material from 0 to 55% of cement, a fraction of carbonate material from 0 to 35% of cement, a fraction of cooked shale from 0 to 35% of Portland cement.

[069] One or more filer comprises a fraction of 10 to 50% of the mixture, preferably said fraction of 20% to 40% of the filer, being even more preferable, the fraction of 25% to 35% of filer in the mixture.

[070] Said fillers are comprised of an inorganic material obtained from the grinding of its raw material or its granulometric classification, being the raw material of the filer, including, but not limited to: limestone or quartz or silica or cristobalite or nepheline or dolomite or granite or electrofilter powder or slag or fly ash or pozzolans or concrete waste or construction and demolition waste or a mixture of these.

[071] The present invention has a first filler with a BET surface area less than or equal to 6 m ² / g, and has a granulometric distribution with an average area defined by the range of 4pm <d98 <40pm. The second filler may have a BET surface area less than or equal to 2.3 m ² / g, with a granulometric distribution of an average area of 6pm <d85 <40pm.

[072] In any form or combination of surface area and granulometry, the porosity of the packaging of the mixture must be at least 0.5 percentage point less than the porosity of the packaging of Portland cement used in this mixture. Preferably, the porosity of the packaging of the mixture is at least 1 percentage point less than the porosity of the packaging of the Portland cement, with even more preferable the porosity of the packaging of the mixture being at least 2.5 percentage points less than the porosity. Portland cement packaging.

[073] The mixture of fines of the present invention provides a reduction of the additive demand in the concrete or in the paste, compared to Portland cement of at least 10%, preferably this reduction of at least 20%, being even more preferable, a reduction of at least 40%.

[074] The mixture of fines of the present invention reduces the viscosity in concrete or slurry. This reduction compared to Portland cement is greater than or equal to 10%, being preferably greater than or equal to 20%, being more preferably greater than or equal to 40%.

[075] Preferably, the fines mixture of the present invention has the first filler with a BET surface area less than or equal to 6 m ² / g and particle size distribution with an average area in the range 5pm <d98 <30pm, preferably being the range of 5pm <d98 <20pm. [076] Even more preferable, the mixture of fines has the first filler of BET surface area less than or equal to 6 m ² / g and granulometric distribution with average area defined by the range 6pm <d98 <16pm.

[077] The mixture of fines of the present invention also provides a reduction of the expansion by the alkali reaction aggregated in concrete, compared to Portland cement, of at least 10%, being preferably the reduction of the expansion by the alkali reaction aggregated in concrete of at least 25 %, being even more preferred the reduction of the expansion by the alkali reaction aggregated in concrete of at least 40%.

[078] The mixture of fines of the present invention provides a reduction of mortar shrinkage, compared to Portland cement, of at least 10%, and, preferably, the invention provides reduction of mortar shrinkage, compared to Portland cement, of at least 20%, and, even more preferably, it provides a reduction of shrinkage in mortar, compared to Portland cement, of at least 30%.

[079] Figure 1 shows the characterization of limestone fillers, discrete particle size distribution, according to the laser granulometry method, as well as cement. Figure 2 shows the accumulated particle size curve of the filers.

[080] The specific masses of the fillers of the present invention are predominantly in the range of 2.6 to 2.7 g / cm ³ , however, the specific masses are not limited to the range used for limestone fillers, covering other fillers, with different specific masses.

[081] Table 1 shows the specific mass (g / cm ³ ) and the BET specific surface area (m ² / g) of fillers and cement of an embodiment of the present invention. Table 1 - specific mass and specific surface area of the filers

Demand for additive in the mixture paste using filer

[082] The evaluation of the properties of the pastes in the fresh state was carried out in two stages: determination of the optimum content of water-reducing additive for each raw material and determination of the rheological properties of the mixed pastes.

[083] After determining the optimum content for each pure raw material, the mixed pastes were evaluated by varying the proportions and using the ideal amount of additive for each case.

[084] The optimized additive content is obtained from the rheological parameters: yield stress, apparent viscosity and hysteresis area. The choice of the optimized content of the additive was made after the viscosity stabilized, but the flow stress and, mainly, the hysteresis area as close to zero as possible should also be taken into account.

Reduction of additive demand through the use of paste filer

[085] In the evaluated raw materials, the optimized levels of the superplasticizer additive were:

_• Cement = 1.0%

_• Filer 2 = 0.3%

Filer 1 = 0.5%

[086] Figure 3 shows the deflocculation curve of pure materials, yield stress as a function of the additive content. Figure 4 shows the deflocculation curve of the pure materials, apparent viscosity depending on the additive content. Figure 5 shows the deflocculation curve of pure materials, area of hysteresis as a function of the additive content.

[087] The evaluation of the properties of mixed pastes, with the optimized additive content, was carried out in two stages: variation of the cement content, Filer 2 and water and variation of the cement proportion, Filer 1 and Filer 2.

[088] All additive contents were dosed in bulk and for use in mixed pastes, the weighted average criterion was adopted according to the proportion of raw materials in each paste. For example, for a paste with 70% cement, 10% Filer 2 and 20% Filer 1, the content of 0.83% additive (0.7 * 1.0% + 0.1 *) was used 0.3% + 0.2 * 0.5%).

[089] From the analysis of Figures 3 and 4, it is very clear that the use of filer results in a change in yield stress and apparent viscosity. While changing the flow voltage, the minimum tension required to start the flow is observed, the apparent viscosity indicates the resistance of the fluid to the flow (energy dissipation parameter).

[090] However, it can be seen in Figure 4 that after the replacement of cement by 30% Filer 2, there is no considerable reduction in viscosity, even with a drop in the yield stress. This fact is linked to the small change in packaging, since the replacement by Filer 2 does not enhance the packaging of particles so much. As will be presented later, this target was achieved using Filer 1.

[091] Figure 6 shows the rheological properties of pastes with different contents of Filer 2 and water contents (0.75; 0.9; 1.05 and 1.20%). It should be noted that the results for pastes with 1.05 and 1.20% water did not indicate considerable differences, since they were very fluid and the tests were performed on the minimum detection scale of the equipment. [092] Figure 7 shows the additive demand as a function of the filer content for the mixtures shown in Figures 6a, 6b and 6c. Note that the increase in filer content directly results in a reduction in the dosage of the additive from 1.0% for pure cement to 0.65% of additive with 50% filer. Even with the significant reduction in the dosage of the additive, in up to 30% of filer content, reductions in viscosity and yield stress were still observed. These results show the reduction of the additive demand with the use of filer.

[093] In the case of using Filer 1, better particle packing was obtained and, consequently, changes in rheological properties were intensified, as shown in Figure 8.

[094] The most considerable changes occurred in viscosity with the increase in the amount of Filer 1. There was a decrease of an order of magnitude in apparent viscosity. It can also be noted a linear correlation between the porosity of the fines packaging and the apparent viscosity of the pastes, as shown in Figure 9.

[095] Likewise, it was observed that the hysteresis area decreased by two orders of magnitude as shown in Figure 8c, indicating the best dispersion of the pastes and that the rheological profile tends to change from dilator to pseudoplastic, with the increase of Filer 1 fill quantity.

[096] Regarding the alteration of the rheological profile, it is also possible to obtain pastes with pseudoplastic behavior, increasing the amount of water, but this is not an advantageous alternative, since the greater the amount of liquid used in the mixture , the greater the amount of pores and, consequently, the lesser the mechanical resistance.

Fresh or hardened concrete

[097] The present invention also has as its object a fresh or hardened concrete composed of said mixture in which: - the amount of the mixture is 200 to 500 kg / m ³ , more preferably 300 to 400 kg / m ³ ;

- the amount of water is less than 180 l / m ³ , with 165 l / m ³ being more preferable, with 150 l / m ³ being even more preferable;

- the incorporated air content is 0.5 to 5%;

- the small aggregates have a granulometric distribution with an average area of dlO> 90pm and d90 <5mm: from 500 to 1200 kg / m ³ ;

- chemical additives for concrete, including, but not limited to, water reducing additive, air incorporating agent, viscosity reducing agent, setting accelerator or retarder, resistance accelerator or retarder: dosed between 0.3% and 5% of the mass of the said mixture.

[098] In fresh or hardened concrete obtained by means of the mixture of the present invention, fine aggregates are dosed in quantities between 700 and 900 kg / m ³ and coarse aggregates are dosed in quantities between 600 and 1400 kg / m ³ .

[099] The fresh or hardened concrete obtained by means of the mixture of the present invention, has compressive strength at 28 days between 20 and 80 MPa in the hardened state, and apparent viscosity of the concrete below 0.06 Nm / rpm in the fresh state .

[0100] More specifically, the fresh or hardened concrete obtained by means of the mixture of the present invention, has compressive strength at 28 days between 35 and 70 MPa in the hardened state and, apparent viscosity of the concrete below 0.05 Nm / rpm in the fresh state.

[0101] In fresh or hardened concrete, obtained by mixing the present invention, the binder intensity is less than 7 kg / m ³ / MPa, preferably less than 6 kg / m ³ / MPa, being even more preferable less than 5 kg / m ³ / MPa.

Demand for additive in fresh concrete using filer and compressive strength of hardened concrete

[0102] By way of example, they are shown in

Table 2, the formulation of various concretes of the present invention. The porosity of the packaging of the mixture of fines used in these concretes is shown in Table 3. The concretes F0 and A35 are references and the PF50, PF10, PF35, PC35 are examples of the present invention.

Table 2 - Formulation of each proposed concrete

Table 3 - Porosity of the packaging of the mixture of

fine of each concrete

[0103] The evaluation of the properties of the concretes in the fresh state was carried out through the determination of the rheological properties of the concretes with different contents of additive. In the hardened state, resistance to compression at the ages of 14 and 28 days was evaluated.

Reduction of additive demand through the use of filer

[0104] For each concrete evaluated, the content of the water reducing additive (by weight of the fines) to achieve the apparent viscosity of 0.025 N.m / RPM was:

_• PF0 concrete = 1.00%

_• PF50 concrete = 0.33%

_• PF10 concrete = 0.62%

_• PF35 concrete = 0.45%

_• PC35 concrete = 0.61%

_• Concrete A35 = 0.88%

[0105] Figure 10 shows the deflocculation curve of the concretes, considering the flow torque as a function of the additive content. Figure 11 shows the deflocculation curve, considering the apparent viscosity as a function of the additive content.

[0106] Figure 12 shows the additive content (by weight of the fines) necessary to reach the apparent viscosity of 0.025 N.m / RPM as a function of the Filer 1 content in the concrete. Note that the increase in filer content directly results in a reduction in the dosage of the additive from 1.0% for pure cement to 0.33% of additive with 50% filer. Even with the significant reduction in the dosage of the additive, up to 30% of filer content, reductions in viscosity and yield stress were still observed. These results show the reduction of the additive demand with the use of filer.

[0107] Fabela 4 shows the results of compressive strength of the evaluated concretes and Table 5 the binder intensity. Table 4 - Compressive strength of

proposed concrete

Table 5 - Intensity of ligands of

concrete

Durability

Aggregate Alkali Reaction

Examples

[0108] Filer 2 was used for this example and the aggregates used in this realization were a mixture of 85% standard quartz sand (non-reactive aggregates) with a density of 2.65 g / cm ³ and 15% glass sand borosilicate (Pyrex: reactive). The use of crushed borosilicate glass aggregates was justified by the need to detect a clear sign of expansion between the mixtures tested. Formulation

[0109] The formulations used are presented in

Table 6.

Table 6 - Proportion of the mixture of mortars from this embodiment

[0110] In this test, for all mixtures produced, 3 bars (25 ^c 25 ^c 250 mm ³ ) were molded and cured, according to the requirements of ABNT NBR 15577-4: 2008 and the expansion of each bar was measured .

[0111] Figure 13 shows the expansion relative to the C100 mixture as a function of the filer content, indicating a reduction in the expansion from the aggregated alkali reaction, with an increase in the filer content of the mixture.

Retraction

[0112] Normal quartz sand was used as fine aggregates and Filer 2 was used for the filer.

Mixtures

[0113] Table 7 presents the mass quantities of the strokes carried out for planning this example with replacement of cement by limestone filer, as well as two different volumes of paste, defined according to the explanations above.

Table 7 - Proportion of the mortar mixture in the experiment

[0114] The retraction measurement tests were performed according to the determinations of the technical standards ASTM C157-08 and NBR 15261.

[0115] 3 specimens of 25 x 25 x 285mm were molded for each mixture, with steel pins for measurements at the ends. The specimens are demoulded after 48 hours and pass to the dry chamber with temperature 23 ± 2 ° C and relative humidity 50 ± 5%, and measurements are taken (variation in size and mass) after 1, 2, 7, 14 and 28 days. Further details on the test procedures and calculations can be found in NBR 15261.

[0116] As shown in Figure 14, for the same paste volume conditions, shrinkage was decreased in the pastes as the limestone filler increased.

Heat of hydration

[0117] The heat released in the hydration of the cement comes from the chemical hydration reactions that take place when mixing it with water (initial formation of etringite, second formation of etringite, formation of CSH from alite, transformation of etringite into monosulfoaluminate, hydration of the ferrite phase).

[0118] As the filler is an inert material or less reactive than Portland cement, this released heat is reduced.

[0119] To determine variations in hydration kinetics, the conduction isothermal calorimetry test was performed. This technique consists in measuring the heat generated in the sample, due to the exothermic chemical reactions of hydration of the cement.

[0120] Two tests were carried out on pastes with constant water / solids ratio. The first consisted of 100% Portland cement (C100) and the second, a 70% cement mixture Portland and 30% Filer 2 (C70). For both pastes, the accumulated heat released in 24 hours was measured. The C70 mixture presented a heat of hydration 23% lower than that of the C100, according to Table 8, showing the effect of the filler in reducing the release of heat of hydration.

Table 8 - Accumulated hydration heat for the mixtures

[0121] In the blend of fines of the present invention the reduction of the heat of hydration, compared to the Portland cement used in this mixture, was at least 10%, preferably at least 20%, being even more preferably 30%.

Process of mixing and homogenizing said mixture of fines

[0122] The present invention teaches a process of mixing and homogenizing the mixture of fines of the present invention, where the elements of said mixture are mixed in a particle mixer in one unit, the said unit receiving, mixing, homogeneity and dispatch said mixture of fines.

Production process of said fresh concrete

[0123] The production process of fresh or hardened concrete is carried out in a concrete batching or mixing plant, in which Portland cement and the mixture filler of the present invention are received: mixed or separately, both Portland cement and the filler is dosed, mixed and homogenized with the other materials.

Example (F35)

Concrete applied on site

[0124] The dosage of materials, mixing, transport, delivery, application and performance of the concrete (F35) exemplified in the present invention was evaluated on a full scale and compared to a conventional concrete (C). The evaluated concretes are shown in Table 9.

Table 9 - Traces

[0125] The result of the rheological behavior (torque) is shown in Figure 15 and Table 10.

Table 10 - Rheological parameters of concretes applied on site

[0126] The compressive strength results of the hardened concrete are shown in Table 11 and the binder intensity shown in Table 12. Table 11 - Results of compressive strength of the two concretes at different ages

Table 12 - Binder intensity of each concrete

Claims

1. A mixture of fines, comprising: a Portland cement, where said Portland cement comprises a fraction of clinker plus calcium sulfate from 5 to 100% of the cement and, alternatively, a fraction of granulated slag from the blast furnace from 0 to 95% of cement, a fraction of pozzolanic material from 0 to 55% of cement, a fraction of carbonate material from 0 to 35% of cement, a fraction of cooked shale from 0 to 35% of Portland cement; further comprising a first filer and / or a second filer, characterized by Portland cement having a fraction of 50 to 90% of the mixture, with the first filer or the second filer or a combination thereof having a fraction of 10 to 50% of the mixture ; one or both fillets consisting of inorganic material from the grinding of its raw material or obtained by granulometric classification of its raw material, said raw material, including but not limited to, limestone or quartz or silica or cristobalite or nepheline or dolomite or granite or dust from the oven dedusting system or slag or fly ash or pozzolans or concrete waste or construction or demolition waste or a mixture thereof, where the first filler has a BET surface area less than or equal to 6 m ² / g has a granulometric distribution with an average area defined by the range of 4pm <d98 <40pm and a second filler has a BET surface area less than or equal to 2.3 m ² / g and a granulometric distribution of an average area of 6pm <d85 <40pm, the porosity of the mixture packaging being at least 0.5 percentage point less than the porosity of the packaging of Portland cement used in the present mixture.

2. The mixture of fines, according to claim 1, characterized by the fact that the fraction preferably comprises 60 to 80% of Portland cement and preferably 20% to 40% of the filler.

3. The mixture of fines, according to claim 1, characterized by the fact that the fraction comprises more preferably 65 to 75% of Portland cement and 25% to 35% of filler.

4. The mixture of fines, according to claim 1, characterized in that the porosity of the packaging of the mixture is at least 1 percentage point less than the porosity of the packaging of the Portland cement used in the present mixture.

5. The mixture of fines, according to claim 1, characterized by the fact that the porosity of the mixture packaging is at least 2.5 percentage points less than the porosity of the packaging of Portland cement used in the present mixture.

6. The mixture of fines, according to claim 1, characterized by the fact that the reduction in demand for additives in concrete or paste, compared to Portland cement used in the present mixture, is at least 10%.

7. The mixture of fines, according to claim 1, characterized by the fact that the reduction in demand for additives in concrete or paste, compared to Portland cement used in the present mixture is at least 20%.

8. The mixture of fines, according to claim 1, characterized by the fact that the reduction in demand for additives in concrete or in paste, compared to Portland cement used in the present mixture is at least 40%.

9. The mixture of fines, according to claim 1, characterized by the fact that the reduction of viscosity in the concrete or in the paste, compared to the Portland cement used in the present mixture is greater than or equal to 10%.

10. The mixture of fines, according to claim 1, characterized by the fact that the reduction of viscosity in the concrete or in the paste, compared to the Portland cement used in the present mixture is greater than or equal to 20%.

11. The mixture of fines, according to claim 1, characterized by the fact that the reduction of viscosity in the concrete or in the paste, compared to the Portland cement used in the present mixture is greater than or equal to 40%.

12. The mixture of fines, according to claim 1, characterized by the fact that the first filer has a BET surface area less than or equal to 6 m ² / g and granulometric distribution with an average area defined by the range of 5pm <d98 <30pm.

13. The mixture of fines, according to claim 1, characterized by the fact that the first filer has a BET surface area less than or equal to 6 m ² / g and granulometric distribution with an average area defined by the range of 5pm <d98 <20pm.

14. The mixture of fines, according to claim 1, characterized by the fact that the first filer has a BET surface area less than or equal to 6 m ² / g and granulometric distribution with an average area defined by the range of 6pm <d98 <16pm.

15. The mixture of fines, according to claim 1, characterized by the fact that the reduction in expansion by the alkali reaction added to concrete, compared to the Portland cement used in the present mixture, is at least 10%.

16. The mixture of fines, according to claim 1, characterized by the fact that the reduction of expansion by the aggregated alkali reaction, compared to cement

Portland used in the present mixture, be at least 25%.

17. The mixture of fines, according to claim 1, characterized by the fact that the reduction of expansion by the aggregated alkali reaction, compared to cement

Portland used in the present mixture, be at least 40%.

18. The mixture of fines, according to claim 1, characterized by the fact that the reduction of mortar shrinkage, compared to Portland cement used in the present mixture, is at least 10%.

19. The mixture of fines, according to claim 1, characterized by the fact that the reduction of shrinkage in mortar, compared to the Portland cement used in the present mixture, is at least 20%.

20. The mixture of fines, according to claim 1, characterized by the fact that the reduction of shrinkage in mortar, compared to the Portland cement used in the present mixture, is at least 30%.

21. The mixture of fines, according to claim 1, characterized by the fact that the reduction of heat of hydration, compared to the Portland cement used in this mixture, is at least 10%.

22. The mixture of fines, according to claim 1, characterized by the fact that the reduction of the heat of hydration, compared to the Portland cement used in this mixture, is at least 20%.

23. The mixture of fines, according to claim 1, characterized by the fact that the reduction of the heat of hydration, compared to the Portland cement used in this mixture, is at least 30%.

24. A fresh or hardened concrete composed of the mixture of claim 1, characterized by the fact:

- the amount of the mixture is 200 to 500 kg / m ³ ;

- the amount of water is less than 180 l / m ³ ;

- the incorporated air content is 0.5 to 5%;

- the small aggregates have a particle size distribution with an average area of dlO> 90pm and d90 <5mm: from 500 to 1200 kg / m ³ ;

- that the coarse aggregates have a granulometric distribution average area characterized by dlO> 5mm: from 600 to 1400 kg / m ³ ; - chemical additives for concrete, including, but not limited to, water reducing additive, air incorporating agent, viscosity reducing agent, setting accelerator or retarder, resistance accelerator or retarder: dosed between 0.3% and 5% of the mass of the mixture of claim 1.

25. The fresh or hardened concrete according to claim 24, characterized in that the amount of the mixture of claim 1 is from 300 to 400kg / m ³ .

26. The fresh or hardened concrete according to claim 24, characterized in that the amount of water is less than 165 l / m ³ .

27. The fresh or hardened concrete according to claim 24, characterized in that the amount of water is less than 150 l / m ³ .

28. The fresh or hardened concrete according to claim 24, characterized in that the small aggregates are dosed in quantities between 700 and 900 kg / m ³ .

29. Fresh or hardened concrete, according to claim 24, characterized by the fact that coarse aggregates are dosed in quantities between 600 and 1400 kg / m ³ .

30. Fresh or hardened concrete, according to claim 24, characterized by the fact that it has compressive strength at 28 days between 20 and 80 MPa in the hardened state and apparent viscosity of the concrete below 0.06 N. m / rpm in the fresh state.

31. The fresh or hardened concrete, according to claim 24, characterized by the fact that it has compressive strength at 28 days between 35 and 70 MPa in the hardened state and apparent viscosity of the concrete below 0.05 N. m / rpm in the fresh state.

32. The fresh or hardened concrete according to claim 24, characterized by the fact that the binder intensity is less than 7 kg / m ³ / MPa.

33. The fresh or hardened concrete according to claim 24, characterized in that the binder intensity is preferably less than 6 kg / m ³ / MPa.

34. The fresh or hardened concrete according to claim 24, characterized in that the binder intensity is more preferably less than 5 kg / m ³ / MPa.

35. A process for mixing and homogenizing the fines mixture of claim 1, characterized in that the elements of said mixture are mixed in a particle mixer in one unit, the said unit receiving, mixing, homogenizing and dispatching said mixture of fines, and alternatively the process of mixing and homogenizing fines can also occur at the end of the grinding of one of the elements through a dosing scale and feeding the flow of ground materials.

36. The concrete production process of claim 24, characterized by the fact that the production is carried out in a concrete batching or mixing plant, in which the Portland cement and the mixture filler of claim 1 are received mixed or separately, both of which Portland cement and filler are dosed, mixed and homogenized with the other materials.