FI124633B - Structured cementitious binder - Google Patents

Description

Structured cementitious binder

The present invention relates to a granular composition which is suitable for the preparation of a concrete mass, and to a concrete mass containing a granular composition. The invention further relates to processes for the preparation of granular composition and concrete mass.

Cement and concrete made from it are difficult to define, and at least neither concept can be described unambiguously, especially when changes occur, for example, with time, ambient temperature and humidity. However, most common binders have in common that they are water-curable and such binders are called hydraulic binders. An example of such binders is Portland cement. The present invention contemplates, inter alia, this type of cement, its components, and the accompanying and recovery events of its hydration.

The main components of Portland cement are tricalcium silicate (C3S, 54%), di-silicate (C2S, 17%), tricalcium aluminate (C3A, 10%) and tetracalcium aluminoferrite (C4AF, 10%). The latter two are essentially only clinker formers, which do not play a major role in the strength provided by the binder.

One mole of CsS releases 3 moles of hydroxy dioxide (Ca (OH) 2) when hydrated, and one mole of C2S, respectively, liberates one mole of Ca (OH) 2 in hydration. The fastest cured is C3A, which requires 6 moles of water to cure, such as C3AF. Compressive strength initially develops mainly from C3S hydration and over a long period (> 90 days) of C2S hydration, which gives the same final strength as the C3S hydration product. These strengths reach about 25 ° C in about one year at normal temperature, i.e. substantially the same time. The theoretical co-water / cement ratio where all water would be consumed for hydration would be 0.245 for the co composition described above. In practice, however, the water-cement ratio is higher in the so-called. gel x water solution, which is about 18%. Here, water has penetrated pores of about 2 nm. This water, which is slowly consumed for hydration, causes shrinkage in the concrete mass, as does carbonation of Ca (OH) 2.

m 00 o o

C \ J

When making concrete, it is also possible to achieve bond strength by means of reactions other than the so-called. by reaction of clinker minerals and water. The pozzolanic reaction is called when the silicate mineral reacts with lime and water, ie, binds lime instead of liberating it as happens in the reaction of CsS and C2S. The pozzolanic reaction is basically the reaction of potassium hydroxide (CH), silica S1O2 [in cement (S)] and water (H) where CSH is formed, as well as CAH and CASH, according to the pozzolanic material. When heat treated at 500-800 ° C 5, kaolin loses its crystalline water and produces Al 2 O 3 · S 1 O 2, which is pozzolanically active in water, called metakaolin. Among other things, metakaolin has been studied to be more potent than microsilica and more effective to compact concrete.

A third way to achieve bond strength in a mineral binder is to allow the small particles to combine to crystallize into larger ones. According to Gibbs's law: Σ ai gi - »minimum, where ai is the surface area of the particles and gi = the surface energy of the particle surface. This means that small particles always try to grow larger, and further that the smaller the particles, the faster the growth, provided that the material is even slightly water-soluble.

Previously, U.S. Patent No. 6,027,561 to Engelhard Corporation, for example, has treated the use of metakaolin with a cementitious binder such that metakaolin has been spray-dried to form metakaolin agglomerates mixed with cement in a proportion of at least 40% metakaolin to water. According to this patent, the agglomerates of met-metakaolin remain intact when mixing the concrete mass and reduce the veden 25 water requirement by about 10% compared to having the same amount of metakaolin as separate particles. However, the previous patent does not determine the ratio of these two basic components, which would be advantageous and even optimal for generating strength.

X

X

CL

In U.S. Patent No. 5,788,762, Ash Grove Company discloses the use of metakaolin as pozzolan in cement m 5) 30 so that after burning, the metakaolin is milled to a working water / binder ratio of 33% or less. This means that the

CVJ

the line cannot be milled further because the need for water is increasing significantly. According to the present invention, metakaolin is introduced into the mixture together with the other binder components 3 in moderately sized agglomerates, whereby the need for mixing water does not increase due to the high content of fines and the viscosity of the pulp is not high.

5 When looking at mixing technology from the point of view of cement production, there is little literature on how difficult near-solid phase mixing is. When mixing liquids, there is always turbulence and diffusion, which helps the final mix. When agitating the concrete mass, no agitation occurs, but the pressure and kinetic energy of the mixing member must bring all the materials as close together as desired. 10 Thus, a substantially complete mix of concrete masses is practically non-existent. The situation is still simple when mixing only aggregate, cement and water. When other components are included, the need for mixing is emphasized. Sidney Diamond, School of Civil Engineering, Purdue University, West Lafayette USA, 2005, has reported that the aggregates of the fines do not separate even during 30 minutes of concrete mixing, while the corresponding normal mixing time is 1.5-2 minutes.

There is a need for a binder composition which gives high strength to the concrete or mortar produced therefrom, thereby preventing, inter alia, the formation of cracks, from which a substantially homogeneous concrete mass can be easily and quickly produced.

20

It is an object of the present invention to provide such a high strength composition wherein the binder composition is in a form where its components are already very close to one another.

Surprisingly, it has been found that by forming granules of the components of the binder composition, each of which contains the required components in predetermined proportions, a composition is obtained which is easily mixed with the other components of the concrete mass.

cc

CL

The present invention thus relates to a granular composition for the preparation of concrete mass, m

10 IA

More particularly, the granular composition according to the present invention is characterized by what is set forth in the characterizing parts of claim 1.

4

The process for preparing the composition according to the invention, in turn, is characterized by what is claimed in claim 9, the concrete mass according to the invention is characterized by what is stated in claim 16 and the process for producing concrete mass according to the invention is characterized by claim 18.

The invention thus provides all strength enhancing components at the same time correctly positioned and proportional to the concrete mass production and utilizes separate strength-providing mechanisms optimally at the same time.

10

Reactive materials introduced in close proximity to the granule are an advantageous route and will also remain in close proximity to one another during the normal mixing of concrete where the reactions occur. The part which is disintegrated in the mix is homogeneously distributed in the mass, since the sources of distribution (granules) are already homogeneously distributed in the mixing of the concrete.

Other details and advantages of the invention will be apparent from the following detailed description.

Fig. 1 is a drawing showing the appearance of granules at 240 times magnification, differently prepared, the fluid of Fig. 1a, and non-fluid in Figs. Ib, le and Id, wherein the fluid refers to metakaolin agglomerates coated in the gas stream and non-fluid.

Fig. 2 shows electron microscope images of the metakaolin grid according to the invention, Fig. 2a as a 250x magnification and Fig. 2b as a 4,000x magnification.

c \ j

X

X

o_

The present invention relates to a granular composition suitable for the preparation of concrete mass, wherein the granules of the composition each contain binder, excipient and fines in predetermined proportions.

c \ j 5

Preferably, the granules of the granular composition comprise: - a hydraulic binder, - a pozzolanic binder, pre-agglomerated, a fines, preferably calcium carbonate, finely ground, preferably 5 calcium carbonate nanoparticles, a plasticizer, and - a small amount of water.

The pozzolanic binder is preferably kaolinite-containing calcined clay or kaolin, most preferably metakaolin. This agglomerated binder is calcined in the final composition to such an extent that at least its outer surfaces are substantially calcined.

The ratio of hydraulic binder to pozzolanic binder in hydrocarbon di a hydration is such that the pozzolanic binder binds up to 90% of the released carbohydrate.

In the present invention, the third binder is a dimension that is not based on a hydraulic reaction but on an autonomous reduction of surface energy. These together optimize the strength of the mortar or concrete. The use of the pozzolan reaction, in turn, is optimized according to the present invention. For example, Engelhaard's U.S. Patent No. 6,027,561 does not justify the use of pozzolans other than to provide a higher purity of comminution compared to the non-agglomeration of metakaolin before mixing with cement and finally water. In that patent, calcining is performed prior to agglomeration, when these steps are performed in the reverse order of the present invention.

It is generally known that limestone in concrete corrects even cracks in it because g CaCO3 is slightly soluble in water (thus forming cave stalagmites). Limestone i as a concrete aggregate gives Puri stusluj a new concrete which is at least the same, preferably

CL

larger than that obtained with the granite aggregate.

ro λ a c \ i 30

LO

The fine aggregate used in the invention, i.e., "filler" or "microfiller," is preferably limestone because it achieves both carbonate coalescence and so-called "carbonate". solid solution between CaCO 3 and Ca (OH) 2 (Lea, The Chemistry of Cement and Concrete, Third Edition, 1970, page 266). Tricalcium aluminum hydrate is also rapidly formed. This limestone can be blended with the '' granule '' preferably in the range of 2 to 30% by weight of the granule, most preferably about 15%.

According to the present invention, all the components are brought as close to each other as possible by the formation of granules. The pre-mixed binder system is thus already sold to the concrete manufacturer in the dry phase. The binder system, i.e. the grain composition, can be varied for different needs. Metakaolin can be replaced or supplemented with silica, cement with aluminate cement, etc. The idea of the invention is to assemble all functional components in a single granule. The granules are easily mixed with aggregate material and water to form a more homogeneous mixture of homo-10, and the mixture is easy to dispense in the manufacture of concrete. The concrete manufacturer only needs to buy a "granule" for a particular purpose and only one silo for the binder.

The products described above form spherical granules of 20-120 µm in size, preferably 80-100 µm in size. The granules of these granules are preferably metakaolin agglomerate having a particle size of 10 to 100 µm, preferably about 50 µm. Other substances adhere to its surface such that the extender forms a band of about 10 µm on the surface of the nanoparticles of nanoparticles in the range of 2 to 500 µm, preferably about 50 µm. Cement particles typically expand 2.06 times during granule production and fill the gap between aggregate particles.

A typical granular composition according to the invention is as follows: Metakaolin agglomerate 20-60 kg / m3 concrete 10-100 µm 25 Portland cement 250 - "- 2-100 µm CaCO3 nanoparticles 10-40 -" - 2-1000 nm

Of fine aggregate 100 - ”- 0.1 to 100 µm

Er Plasterer 2

CL

m m 5) Typically, polyacrylamide, lignosulfonate, naphthalene sulfonate or melamine sulfonate or more of these, most preferably their polymers, may be used as plasticizers.

Advantageously, all of the adjuvants and adjuvants and the like are brought into the same granule for mixing the concrete mass, while the customer only has to dispense the aggregates and water in addition to the granules.

The granules contain a large number of pores which bind and absorb water with their capillary forces over a period of time which is subsequently used for hydration of hydraulic binder components. At the same time, the apparent water-to-cement ratio during mixing and during concrete casting is relatively high, which makes it easy to cast and yet stiffens within the mold relatively quickly. If the calcination of kaolin has been carried out with flue gases or otherwise in a carbon dioxide atmosphere, the Ca (OH) 2 formed by hydration immediately forms more precipitated CaCCE. The Gibbs equation (Ea® - »minimum) also explains why precipitating substances always precipitate on the surface of another particle. Minimization occurs faster when the contact point is not counted as a formed surface.

According to a preferred embodiment of the present invention, the granules are prepared by first bringing together a pozzolanic binder such as metakaolin, fines and hydraulic cement, followed by the addition of water, presumably carbonate, and a hardener. In the present invention, the extender is preferably attached to CaCOs before being added to the mixture.

20

Preferably, kaolin is first agglomerated, e.g., by spray drying, and then calcined to metakaolin, preferably with hot flue gases. Thereafter, the metakaolin agglomerate (MKA) is contacted with the desired type of hydraulic cement, preferably in the presence of a dispersant, and finally the structured o-bicomponent agglomerate is coated, e.g. in a gas stream, with finely divided calcium carbonate powder. nano-particle with calcium carbonate (n-PCC), i co prepared by precipitation. All of these particles have been found to have a tendency to x agglomerate into ever larger particle aggregates, which are only decomposed by a high shear force. It is still advantageous to contact the granulate with the finest powder.

LO

Drain with 30 lime limestone filler. The ground limestone can preferably be used in a quantity of about 15% of cement, preferably increasing the workability of the concrete mass.

CVJ

According to another embodiment, the granule is prepared by first mixing a pozzolanic binder such as kaolinite clay with water and optionally adding 8 additives, preferably inorganic, to a dry matter content of 30-70%, drying the slurry in a gas stream and further calcining at least 500 850 ° C in a gas stream, in a manner known per se, but preferably in a gas stream containing carbon dioxide. On the surface of the quenched chilled metakaolin agglomerate, 5 concrete compactors are sprayed in an appropriate amount to bond the cement particles to the surface of the agglomerate when the cement dust and agglomerates are contacted. It should be noted that cement dust and metakaolin adhere to one another due to triboelectric charge without the use of a concrete grout. During the studies of the invention, metakaolin has been found to collect other particles on its surface.

10

In the next step, CaCO 3 nano particles and ground limestone are blown into the powder stream.

In a third embodiment, the corresponding binder granule is prepared by bringing the metakaolin-agglomerate and hydraulic binder and limestone filler together in a dusty (fluid) form and allowing the particles to stabilize, e.g., in a fluidized bed for 10-60 seconds and then spray with a plasticizer. The amount of water introduced into the mixture with the precipitated calcium carbonate is such that it does not provide more than 5-10% of the chemical water requirement of the hydraulic binder.

According to a fourth embodiment, the other powders are mixed dry with one another and lastly mixed with metakaolin agglomerates which collect the other particles on their surface.

't δ 25

CM

co Concrete or mortar mixes normally have moderate shear forces that remove the i co excess layers from the surface of the formed granule, but we find that x leaves all three layers sufficiently in place. The method for forming metakaolin agglomerates described in Engelhard's patent differs substantially from the present invention.

LO

cm 30 only for the process whereby the agglomerates are formed in the aqueous solution before calcination and co § which guarantees that the agglomerate (calcining) has a strong structure. At the same time, it saves energy.

CM

when it is essentially necessary to calcine only the outer surface of the agglomerate.

9

The strength of the structure can be further improved by mixing the water-soluble inorganic compound with the mixing water, e.g. spray-drying mixing water, which dries the inorganic material and binds more particles to each other. Such a water-soluble material is preferably a water glass, which upon drying dissolves only in boiling water. The gypsum can be used for the same purpose, or soluble organic salts of calcium, such as formate or acetate, in which case the organic portion is calcined when calcined. This agglomeration before calcination or partial calcination is discussed, inter alia, in our previous patent application, US 20050000393.

According to a preferred embodiment of the invention, the so-called lime-stone component of this binder is introduced into the binder granule. on a nano-scale because, in a suitable environment, it is precisely the nanoscale particles that tend to grow the fastest. The growing, recrystallizing particle adheres to the surface of the other particles, usually by mechanical forces and so called. van der Waals proximity forces. In addition, the calcium carbonate-nano particles have the property that they facilitate the workability of the concrete mass.

Further, when dispersants which are placed inside the granule are introduced into the binder granule, a product with only binder granules, aggregate and water is measured.

20

The concrete mass according to the invention, when mixed with each other, contains the granular composition described above, as well as aggregate and water.

The pulp is made from this composition, which contains at least a binder, excipient and a fines in predetermined proportions, followed by mixing said granules co with rock and water, co

C \ J

The only deviating requirement of the present invention as compared to normal concrete mixing is that it requires a mixer and mixing energy which is more intense, not temporally, but in terms of power / volume. Preferably, the mixing is continuous.

o c \ j

The following non-limiting example illustrates the invention and its advantages.

10

Example

The kaolin was slurried by first mixing it in a 55% aqueous slurry, then treating it with a dispersant and adjusting the pH to 7.5 with NaOH. A slurry having a viscosity of 5 520 cP at 21 ° C was obtained. A saturated solution of Ca (HCO3) 2-a was added to the slurry so that,

Calculated as CaCOs, the dissolved carbonate was 1.8% of the dry matter. This slurry was spray dried to give particles of 11.4 μιη, with a dgo of 9.9 μιη. It was found that the agglomerate particles formed were almost uniform in size and spherical.

10 In this experiment, calcination took place in an electric resistance furnace manufactured by Bentrup and was heated in a crucible in batches of 1.5 kg so that the temperature was slowly raised from room temperature to 1050 ° C for one hour. The total weight loss was 12.61%, from which it could be calculated that the kaolinite content was apparently 88%.

The granules of the invention (Figure 2) were prepared by mixing under dry conditions the ingredients of the following composition (Figure 1, non-fluid):

Metakaolin agglomerate 20-40 kg / m3 concrete 10-100 µm

Portland cement 250 - "- 2-100 µm 20 CaCCL nanoparticles 10-40 -" - 2-500 pm

Microfillers 100 - ”- 0.1-100 µm

Extender 2 '' t To this composition, nano-PCC was first added with a small amount of water and? 25 with the water supplied with the extender. Water was used in a total of 7% of the total solids and 10% of the cement. The composition of each formed granule corresponded to this average composition of co cm.

X

DC

CL

LO

LO

C \ 1

LO

C/O

O

O

C \ 1

Claims (17)

1. A granular composition for the production of concrete pulp, characterized in that the granules of the composition each contain binder, auxiliary material and immaterial in a predetermined proportion, wherein the binder contains agglomerated pozzolant binder which is calcined so long that at least its outer surfaces are substantial. Composition according to claim 1, characterized in that the size of the granules is up to 20-120 µm, preferably up to 80-100 µm, and they are spherical. 10 Composition according to any of the preceding claims, characterized in that its granules contain - hydraulic binder, - pozzolant binder, optionally pre-agglomerated, 15. immaterial, preferably finely ground calcium carbonate, plasticizer and - a small amount of water. Composition according to any of the preceding claims, characterized in that the fine material is present as the calcium carbonate nanoparticles. Composition according to any of the preceding claims, characterized in that the calcium carbonate in the granules is in the range of 2-30% of the total weight of the granule, preferably in about 15%. δ 25 CvJ cd Composition according to claim 3, characterized in that the pozzolanic binder and cd are kaolinite containing calcined clay or kaolin. CvJ X X o_ Composition according to claim 3, characterized in that the ratio of the hydraulic binder which secretes calcium hydroxide in the hydration to the pozzolanic binder is such that the pozzolanic binder binds at most 90% of the released calcium hydroxide. Process for preparing a granular composition suitable for preparing concrete pulp, characterized in that the process is agglomerated and then calcined the pozzolanic binder, after which this pozzolanic binder, fine material and hydraulic cement are added to the mixture and water is added to the mixture. , kai ci u mcarb onat 5 and plasticizers. 9. A process according to claim 8, characterized in that the pozzolanic binder is agglomerated and then calcined, after which the agglomerate is contacted with hydraulic cement, and finally the formed structured two-component agglomerate is coated with granulated carbonate or calcium agglomerate in calcium agglomerate in calcium agglomerate. a gas flow containing this. Process according to claim 8, characterized in that the pozzolanic binder is mixed in water to a dry matter content of 30 - 70%, the formed agglomerate slurry is dried in a gas flow and at least the surfaces of the agglomerate are calcined in a gas flow of a temperature. of 500 - 850 ° C, on the surface of the calcined cooled agglomerates, concrete softeners are sprayed, cement dust and the agglomerates are contacted with each other and finally biases CaCCF nanoparticles and ground limestone powder into the powder flow. 20 Process according to claim 9 or 10, characterized in that the gas flow contains carbon dioxide. Process according to claim 10, characterized in that kaolin binder or clay containing kaolinite is mixed in water and agglomerated in such a way that in the mixing water o before dissolving a small amount of soluble site, such as water glass, Ca citrate, is dissolved. plaster cows or calcium bicarbonate. cp co C \ 1 x 13. A process according to claim 8, characterized in that the metakaolin agglomerate and hydraulic binder and limestone filler are brought together in fluid form and the particles LO 30 are allowed to stabilize in fluidized bed for a period of 10-60 seconds and then 00 g of the precipitated cesium carbonate slurry is sprayed. along with plasticizers. C \ l Process according to Claim 8, characterized in that the binder, immaterial and calcium carbonate are mixed in a dry state with each other, after which the metakaolin agglomerates which collect other particles on their surface are added. Softener 2 15. Concrete pulp, characterized in that it contains, mixed with each other, a granular composition according to any one of claims 1 to 7 as well as stone material and the water. 16. Concrete pulp according to claim 15, characterized in that it contains the following components in said amounts: 10 Metakaolin agglomerate 20-60 kg / m3 concrete 10-100 µm Portland cement 250 2-100 µm CaCO 3 nanoparticles 10-40 ”- 2-1000 nm Fine milled stone material 100 -” - 0.1-100 pm Process for the preparation of concrete pulp, characterized in that the composition containing binder, auxiliary material and molding material in predetermined proportions is granulated according to any one of claims 8 to 14, after which said granules are mixed with stone material and water. 't δ CM co cp co CM X DC CL LO LO CM LO CO O O CM