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    • 专利摘要:
    Wet chemical analysis method to determine the reactive alumina content of natural and artificial pozzolans. It is a chemical method consisting of a series of steps to determine the reactive alumina sesquioxide content (Al2 O3r-) in natural and artificial pozzolans that can be used in the manufacture of Portland clinker base cements, as well as in the manufacture of Portland cement based concrete and mortars, and is applicable to all of them, considered, regardless of their natural or artificial origin, as materials consisting of small crystalline fractions randomly distributed in a mostly vitreous and/or amorphous matrix in which their most significant and major reactive fractions mentioned above reside: reactive silica, SiO2r-, and reactive alumina, Al2 O3r-, which can be determined its content through this method; since its chemical content depends on its lower or higher content, whether or not it is projected according to the natural aggressive environment considered: sulfates, chlorides or seawater, respectively. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2725320A1
    申请号:ES201800071
    申请日:2018-03-23
    公开日:2019-09-23
    发明作者:Morales Rafael Talero
    申请人:Silico Aluminatos De Calcio Anhidros E Hidratados S L；
    IPC主号:
    专利说明:

    [0001]
    [0002] Wet chemical analysis method to determine the reactive alumina content of natural and artificial pozzolans.
    [0003]
    [0004] Object of the invention
    [0005]
    [0006] The present invention relates to a wet chemical method for determining the content of reactive aluminum sesquioxide (Al203r-) (hereinafter and for short, reactive alumina without further ado) in natural and artificial pozzolans that can be used in the Portland clinker base cement manufacturing.
    [0007]
    [0008] At present, the importance of the construction sector in all countries, from the economic and social point of view, together with the availability of the necessary natural and artificial resources and their sustainable development in addition to the environmental pollution that the clinker manufacturing Portland entails, for several decades now, this part has had to increase, in quantity and types, the incorporation of mineral additions to Portland cement (CP). The interaction that is generated between the two and with the rest of the materials that make up the concrete, mortar or paste, added to the rest of the variables involved in each derived product (reinforced and mass concretes, mortars, pastes and prefabricated) both at the moment of its manufacture and early ages, as in its future benefits, that is, its mechanical strength and durability, above all, constitutes a very broad and extensive subject of research and development. * What has motivated the organization of numerous international events where it is discussed, validated or invalidated, as appropriate, the aptitude or not of the use of these or those mineral additions in certain types of works and / or in certain media, to the To exchange experiences.
    [0009]
    [0010] All this has also been accelerated today in trying to achieve two fundamental objectives:
    [0011]
    [0012] - The first, exclusive to the cement industry, which is to reduce production costs in addition to pollution by partially replacing Portland cement with these mineral additions, thus obtaining considerable energy savings without any reduction in the production of cement itself and, in addition, greater care and respect for the environment thus making its manufacture sustainable.
    [0013]
    [0014] - The second, of an environmental nature and of double effect, whereby the quantities of cement needed for construction are manufactured without necessarily increasing the manufacture of Portland clinker, but even the opposite, reducing it, which, in accordance with the requirements set for the first time in the Kyoto Protocol, entails the reduction of carbon dioxide emissions into the atmosphere, also being carried out and, on the other hand, the material recovery of different by-products from other industrial sectors that were previously waste and were destined for landfill but now and thus have risen to the range of industrial by-products.
    [0015]
    [0016] Therefore, one of the lines of research with more projection in this sector is the search, detection and achievement of new active and non-active mineral additions or misnamed "inert", to add them to Portland cement but not before having characterized and validated its physical-chemical compatibility with it, whether of natural, artificial, or semi-artificial origin.
    [0017] From 1975 to date it is allowed to build in Spain Building and Civil Works structures with reinforced concrete whose Portland cements could contain up to 20% of natural and / or artificial pozzolanic additions, content that was later expanded by the Instruction of Structural concrete EHE-98 and maintained by its successor in force, EHE-08, up to 35% of fly ash, and silica smoke only up to 10%, by weight of Portland cement type CEM I, in the case of prestressed concrete, and a mixture of both for the case of high-strength concrete that, in any case, will not exceed 20% and 10%, respectively, of the weight of said Portland cement as well, but its quality as well as its durability was very low causing a lot of pathologies in construction with the consequent legal and economic claims for problems in concrete structures, motivated at different stages s of the project, materials manufacturing, execution, maintenance, etc.
    [0018]
    [0019] And all this is due to the natural and artificial pozzolanic additions like fly ash and all other artificial ones, to the steel slags in high amounts of replacement by CP, and to the fillers, referred to earlier, that have been incorporated by regulation in Spain for some time now. more than four decades, to manufacture cements and / or their derivative products, concretes, mortars, pastes and prefabricated products (and in most of the industrialized countries as well), under the same conditions and identical constructive uses as concrete and mortars from CP pure, also dictated, as said before, said use of these residual materials, today industrial by-products, for economic and environmental reasons especially.
    [0020]
    [0021] This is where the main objective of the method of the present invention arises, by circumscribing only natural and artificial pozzolans because they are all considered, regardless of their origin, as materials consisting of small crystalline fractions randomly distributed in a matrix mostly vitreous and / or amorphous which is what gives it its reactivity with calcium hydroxide in the form of lime or portlandite from the hydration of the CP with which they have been mixed. In turn, said vitreous and / or amorphous fractions are constituted, for the most part, by reactive silica, SiO2r “, reactive alumina, AhO3r ~, and reactive iron oxide, Fe2 O3r ~, also receiving, together, the name generic "hydraulic factors" of the pozzolana, which and usually differ quantitatively from their total contents determined by alkaline fusion by standard procedures and, in addition, to a substantial extent most of the time, which justifies their enormous importance and interest for the durability that the pozzolana can confer to the CP to which it is incorporated and its derived products, concretes, mortars, pastes and prefabricated products.
    [0022]
    [0023] Of the three reactive oxides mentioned and from the technical point of view, the most important due to their greater presence in almost all natural and artificial pozzolans and, also, greater importance in chemical durability that can confer them to reinforced concrete and in dough, mortar or Portland cement paste that contains them, are the SiO2r "and the Al2O3r". The first of the two, the SiO2r “, reacts chemically nothing more than with the portlandite (and with Ca (OH) 2) to form CSH gels later transformed into tobermorites or jennites, similar to those that originate the wing and the CP belita in its hydration. And from the normative point of view, the presence of this reactive silicic fraction in the pozzolans is regulated by the UNE-EN 197-1 standard, in general, being also referred to by the standard EN 450-1: 2006, in the context of fly ash in its addition to concrete, such as "a fine powder of particles mainly of spherical and crystalline form, coming from the combustion of pulverized coal, which has pozzolanic properties and which is mainly composed of SiO2 and Al2O3. In addition and in accordance with the first of the two standards, "The content of reactive silicon dioxide (defined and determined according to EN 196-2 or its equivalent UNE 80225) must not be less than 25% by mass ".
    [0024]
    [0025] On the other hand, numerous studies have shown that if pozzolan is not "adequate" in quality or quantity, the chemical durability of the Portland cement to which it is replaced and, consequently, of the derived products that are manufactured with it, mentioned above, may become seriously compromised and undermined by being abnormally low because, unlike reactive silica, SiO2r ", reactive alumina, AhO3r". On the other hand, numerous studies have shown that if pozzolan is not "adequate" in quality or quantity, the chemical durability of the Portland cement to which it is replaced and, consequently, of the derived products that are manufactured with it, mentioned above, it can be seriously compromised and undermined by being abnormally low because, unlike reactive silica, SiO2 r ~, reactive alumina, AhO3r ~, (or tetra- or penta-coordinated aluminum that constitutes it for the most part plus a very small fraction with a polycrystalline aspect corresponding to the crystalline structure of the y-AI2O3 although in its metastable form) it is involved and participates as such in a very direct way and with completely opposed results even, in the most common natural aggressive chemical attacks that occur. they produce from:
    [0026]
    [0027] i. Of selenite lands and waters: sulfates (very abundant in Spain and in many other Mediterranean countries), which attack where appropriate the concrete, mortar, paste and prefabricated material that contains it to form ettringite of rapid formation, ett-rf, the which can even lead to a justifying expansive synergistic effect in turn of a "rapid plaster attack" and some of the "expansive hydraulic cements".
    [0028]
    [0029] ii. Of the de-icing salts and sea dew, especially in the case of Spain: chlorides, which attack, however, the steel reinforcements of the concrete causing their electrochemical corrosion by "pitting", although in this other chemical attack said AhO3r " what originates is Friedel salt of rapid formation, sF-rf, also whose effect is, instead, collimator and protector, in short, so that such electrochemical corrosion does not occur.
    [0030]
    [0031] iii. From seawater: mutual aggressive action of chlorides and sulfates.
    [0032]
    [0033] iv. From "negative" carbonation and arid-alkali reactivity.
    [0034]
    [0035] In addition to intervening:
    [0036]
    [0037] v. In the release of the heat of hydration which can become too high and therefore cause a Calorific Synergistic Effect, as well as,
    [0038]
    [0039] saw. In the inappropriate rheological behavior of their fresh pastes for proper mixing and kneading, transport, pouring, placement and commissioning and vibrating, especially if they are self-compact that do not need it, being able to produce unwanted segregations and exudations of some (s) of its components thus shortening their expected durability and, sometimes, very seriously even. The first four "directly" and the second "indirectly" by generating the concrete or mortar material microcracks and cracks even by thermal retraction, drying and hydraulics which are the perfect atrium through which the aggressive enter with ease previous natural chemicals. Hence, as a final task, the “sealing of fissures” of these concretes had to be implanted for some time.
    [0040]
    [0041] In 1998 a new Structural Concrete Instruction, EHE-98, entered into force in Spain, motivated by the precarious chemical durability shown by such concretes with Pozzolanic additions mentioned as their "useful life" is shorter, this problem residing in the so-called "hydraulic factors" of natural and artificial pozzolanic additions, in general, and in their reactive alumina content, AhO3r- (%), vitrea and / or amorphous, in particular, that said EHE-98 Structural Concrete Instruction did not contemplate. Nor is the new Structural Concrete Instruction that came to replace it ten years later and is in force, EHE-08. And much less still contemplated by the current Instruction for the Reception of Cements RC-16 or any of those that preceded it, which is the most serious of all.
    [0042]
    [0043] At the national level there is a standardized chemical method since 1993, which has also been updated in 2012 and is contemplated by the current Instruction for the Reception of Cements RC-16, for the determination of the content of reactive silica, SiO2r- (%), of any pozzolana, whether natural or artificial. And the most paradoxical of all is that, despite its aforementioned completely opposed behavior against sulfates and chlorides and that to determine its SiO2r content (%), the UNE 80225 standard has been available since 1993, to determine its corresponding AhO3r content (%),
    [0044]
    [0045] - a wet chemical analysis method is not yet available for quantitative determination that is also relatively simple in its operability, truthful, precise, rapid response, from the technical point of view of construction (no more than 28 days ), repeatable, reproducible, that does not imply any danger to the vital security of the people who have to manipulate and put it into practice (technicians of the Chemical Analysis Laboratory by conventional wet route, grade FP II, Bachelor's Degree, COU or equivalent ), economical, and that also serves both for research - scientific background - and especially for quality control - technical background -, and
    [0046]
    [0047] - far from it is not yet available any chemical specification that requires the maximum content of AhO3r- (%) that must have a natural or artificial pozzolan to be able to be added to Portland cement and / or the concrete that will be subjected to a certain aggressive chemical attack of those mentioned above and, especially, sulfates, chlorides or seawater.
    [0048]
    [0049] And for greater abundance and justification of both needs, it must also be said that the current EHE-08 Structural Concrete Instruction, mentioned above, also does not include any chemical specification on both “hydraulic factors”, in general, nor the content of AhO3r- (%) of fly ash, in particular, in its Article 30 "Additions" or in any other Article thereof.
    [0050]
    [0051] There are, however, some chemical methods that, due to some significant or other contrariety, have never deserved or deserved due consideration to be able to be elevated to the UNE standard range, in principle, and much less EN then, which is what essential, which is why they are only used for research only at times but not for quality control, these being the following:
    [0052]
    [0053] > The Florentín Method for all types of Natural and Artificial Puzolanas.
    [0054]
    [0055] > The A. López Ruiz Method for activated clays.
    [0056]
    [0057] > The Method of E. Raask and M.C. Bhaskar for ashes of fuel oil incineration.
    [0058]
    [0059] > The M. Murat and M. Driouche Method for activated clays.
    [0060] > The Method of P. Arjuan, M.R. Silbee and D.M. Roy for fly ash.
    [0061]
    [0062] > The Modification of the method of Arjuan and cois, for fly ash, by A. Fernández-Jiménez et al.,
    [0063]
    [0064] > The determination of the SiO2r- / AhO3r- relationship for activated clays and fly ash, by C. Ruiz-Santaquiteria and cois., And
    [0065]
    [0066] > The thermogravimetric method of L. Trusilewicz for natural and artificial pozzolans that was the subject of his Doctoral Thesis:
    [0067]
    [0068] S Titled: determination of the reactive alumina content of natural and artificial pozzolanic additions, by thermogravimetry and by the Rietveld method.
    [0069]
    [0070] S Read and defended publicly at the Higher Technical School of Engineering and Industrial Design of the Polytechnic University of Madrid (UPM), on January 30, 2014.
    [0071]
    [0072] S Directed by: Dr. D. Rafael Talero Morales and Dr. D. Francisco Fernández Martínez, and
    [0073] S To which it was granted:
    [0074]
    [0075] - Highest academic qualification: outstanding unanimously - cum laude, and
    [0076] - the extraordinary Prize for the best PhD thesis read and defended at the UPM in the 2013-2014 academic year.
    [0077]
    [0078] S This thermogravimetric method is the only one of them that is capable of being able to be elevated to the normative range, so that inter-laboratory reproducibility and repeatability analyzes are essential to achieve it.
    [0079]
    [0080] S This method requires a superior qualified person with enough proven experience in the management of the advanced analytical technique called: Differential Thermal and Thermogravimetric Analysis.
    [0081]
    [0082] Of all of them and to determine the content of the "hydraulic factors" to natural pozzolans, there is only one analytical method, that of Florentín, while to determine them to activated clays and fly ash there is another, that of C. Ruiz-Santaquiteria and cois., while to determine the reactive alumina content, nothing more than natural and artificial pozzolans, there is also Trusilewicz but by means of thermogravimetry. The other five, or are only worth to determine them to activated clays or ashes, whether they are flying or not, although, however and in any case, what must be reviewed and highlighted of all of them is that none has been validated by their authors or elevated at a normative level either for one reason or another.
    [0083]
    [0084] It is here that this method of chemical analysis by wet route is framed, which can be applied to all natural and artificial pozzolans, which, regardless of their origin, are considered as materials consisting of small crystalline fractions randomly distributed in a mostly vitreous matrix and / or amorphous in which their major reactive fractions mentioned above reside: reactive silica, SiO2r- and reactive alumina, A ^ O3r -, being those that actually give them their reactivity with calcium hydroxide in the form of muted lime or of portlandite from the hydration of the synthetic hydraulic constituents of the Portland cement with which they are mixed and, in such a way, that their mixing cements comply with the pozzolanicity test, object of the standard UNE-EN 196-5, at the age of 28 days, although it must be met at the age of 15 days at most. Likewise, both the natural pozzolans and, above all, the artificial type fly ash, also have a reactive Fe III sesquioxide fraction, Fe O3r_, which is usually the smallest and least reactive of the three so, in any In this case, it is the least important of all from the point of view of its contribution to the mechanical strengths and durability referred to before the mixing cement of which its pozzolana is part.
    [0085]
    [0086] So, whatever the natural or artificial pozzolan that is analyzed by means of this analytical method by wet method that is desired to be patented, the quantitative determinations intended and carried out successfully through it can be carried out in a relatively short space of time: in 28 days at most. Therefore, this new method has so much scientific utility, for research, but, above all, technical, for quality control of natural and artificial pozzolanic additions that are regularly and routinely added to Portland cement in the factory and / or its concretes and mortars in plant with a view to ensuring its chemical durability.
    [0087]
    [0088] In addition and on the other hand, the determination of the reactive alumina content, AhO3r ~ (%), of any natural or artificial pozzolan, carried out by the method object of the present invention, allows to deduce without more than the more than probable behavior of the concrete, mortar or CP paste containing the pozzolan thus analyzed against the attack of an aggressive or undetermined chemical medium: sulfates, chlorides, seawater, negative carbonation, RAA, etc., or simply that its hydration without further water does not cause excessive amount of heat and not even high either, or that the Theological behavior of its fresh pasta is inappropriate because it causes difficulties in mixing and kneading its components, transport, pouring, placement and commissioning and vibrating or pumping in the case of that are self-compact, translatable into unnecessary unwanted segregations and exudations in addition to microfisurations and cracks even after setting, which It will inevitably also shorten its expected durability but this time indirectly rather.
    [0089]
    [0090] Background of the invention
    [0091]
    [0092] Although no invention identical to that described has been found, we present below the documents found that reflect the state of the inventive technique related thereto.
    [0093]
    [0094] Thus, ES2369843T3 refers to new hydraulic cements that include reactive magnesium oxide prepared by low temperature calcination. Cements can be formulated to adapt to a large number of applications with various setting times, strength and sustainability levels, either by adding iron salts such as ferrous sulfate or mixing them with other faster-compatible compatible cements such as Portland cement or using both methods The compositions are capable of incorporating relatively large amounts of low-cost pozzolans, such as fly ash, which is one as it is industrial waste or waste. Many excellent properties are exhibited and, in particular, good integral strength and sulfate resistance can be achieved. The aforementioned invention does not include a method for determining the reactive alumina content of pozzolans as it appears in the main invention.
    [0095]
    [0096] EP2744767A2 describes, instead, a production of a clinker ternesitabelite-calcium-sulfoaluminate (ferrit). The invention also relates to the use of alternative raw materials, raw materials based on industrial auxiliary products, in particular, which have a low quality, such as slag and ash pieces with a low content of glass and / or high content of unlaminated lime and / or high content of high temperature crystalline phases, and naturally present minerals and igneous glass of a similar chemical composition for clinker production. Again, it is a production of a type of material where its scope does not include the method for determining the reactive alumina content of the pozzolans, the main object of the present invention.
    [0097]
    [0098] Document ES0264733A1 refers to a calculation rule for the control of the thermal performance of cement kilns from gas analysis, where its scales drawn by concentric circumferences organized in such a way that a circular, rotating band with respect to the other elements, contain on its outer edge a scale and on its inner edge another scale, sliding each of these scales next to the other fixed ones, when the circular band rotates. The process described in said invention for the control of thermal efficiency in cement kilns is not directly related to the analysis procedure described in the main invention.
    [0099]
    [0100] Document ES2569415B1 proposes a method of testing the state of materials, comprising the steps of injecting an input ultrasound signal xinp (n) with a frequency f given in a sample of material to be tested, being f lower or equal to the characteristic frequency of the material under test; receive an output signal x (n) after passing through the sample of material; select a value for a delay between consecutive samples L; select a value for an embedded dimension E; reconstruct a phase space of the signal x (n); calculate a matrix of recurring representations; calculate the degree of determinism; and determining the presence of damage to the material for a DET value of less than 1. Again, said method is not related to the exclusive purpose pursued by the method object of the main invention.
    [0101]
    [0102] Conclusions: As can be seen from the research carried out, none of the documents found solves the problems raised as the proposed invention does.
    [0103]
    [0104] Description of the invention
    [0105]
    [0106] The wet chemical analysis method for determining the reactive alumina content of natural and artificial pozzolans, object of the present invention, describes a conventional wet chemical method for determining the reactive aluminum sesquioxide content (AhO3r ") in the natural and artificial pozzolans that can be used in the manufacture of Portland clinker base cements, and is applicable to ALL of them, considered, regardless of their natural or artificial origin, as materials consisting of small crystalline fractions randomly distributed in a matrix mostly vitreous and / or amorphous in which their major reactive fractions mentioned above reside: reactive silica, SiO2r ", and reactive alumina, AhO3r", which are what actually give them their reactivity with calcium hydroxide in form lime off or portlandite from the hydration of the consti synthetic hydraulic Portland cement stents and, in such a way, that their mixing cements comply with the pozzolanicity test, object of the LINEEN 196-5 standard, at the age of 28 days although they must be met by the age of 15 days at most.
    [0107]
    [0108] The reactive aluminum sesquioxide, expressed as such or as reactive alumina (AhO3r ") of natural and artificial pozzolans is defined, for the purposes of this method of chemical analysis by wet route, as the amount of tetra- or penta-coordinated aluminum in for the most part, plus a very small fraction with a polycrystalline aspect corresponding to the crystalline structure of x-Al2O3 although in its metastable form (in its vitreous and / or amorphous form) that is extracted from them by solubilization at 40 ° C and constant stirring with a saturated solution of calcium hydroxide (Ca (OH) 2) and sodium chloride (NaCl), over time given (maximum: 28 days), in the form of a chemical compound called Friedel's salt (CaO AI2O3 CaCl2 10H2O). Said solubilization is achieved, in fact, by a chemical reaction type><solid-base>> liquid which is produced in an accelerated way in a tightly basic and tightly sealed saline medium.
    [0109]
    [0110] The chemical reaction in particular that takes place in aqueous medium, between the AhO3 r- of the pozzolan (natural or artificial), Ca (OH) 2 and NaCI is as follows:
    [0111]
    [0112] 40 °
    [0113] Al2O3r- 4Ca (OH) 2 2NaCl 6H20 ^
    [0114]
    [0115] The amounts of Ca (OH) 2 and NaCI required for each pozzolan analyzed are determined by calculation, based on the chemical composition of the original pozzolan and the stoichiometry of the chemical reaction (1). Additionally, an excess of both chemical reagents is dosed to ensure adequate conditions of the attack, dissolution and leaching process of the AhO3r-content of the pozzolan and, ultimately, its referred solubilization.
    [0116]
    [0117] Finally, the reactive aluminum sesquioxide (AhO3r -) content of the pozzolan is determined, also according to the stoichiometry of the Friedel salt formation chemical reaction (1), also based on the amount of leftover chlorides or residuals of said chemical reaction that are present in the filtered liquids obtained in the previous operative procedure of solubilization of said AhO3r - content. Said determination consists in the quantitative chemical analysis of the content of said chlorides (Cl-, in mg / l) in excess and that are present in said filtered liquids, by means of the operating procedure object of the UNE 77041: 2002 norm or Mohr method.
    [0118]
    [0119] The general requirements for the tests are as follows:
    [0120]
    [0121] - Number of tests: this determination must be made in duplicate or triplicate at least, at the ages of 7 and 14 and / or 21 (not mandatory) and 28 days (mandatory) in a chemical reactor of alkali-resistant glass or polyethylene with airtight closure in any case. In the event that the pozzolan to be analyzed with this method is a fly ash, this last determination at the age of 28 days does not admit any option and, in addition, it has to be done in quadruplicate.
    [0122]
    [0123] - Repeatability: the repeatability of the test comprises an accuracy under repeatability conditions, where the results of individual determinations have been obtained with the same method, on a material of the same batch tested, in the same laboratory, by the same operator, using the same team and in short intervals of time. Repeatability is expressed as a standard deviation of repeatability according to the characteristic tested.
    [0124]
    [0125] - Expression of the masses, volumes and results: the masses are expressed in grams, with an accuracy of ± 0.0005 g; the volumes measured with burette or pipette, are expressed in milliliters with an accuracy of ± 0.05 ml; and the results of the tests, average of two / three / four determinations at least, referring to the sample of natural or calcined pozzolana or dry fly ash, are expressed as a percentage and with two decimal places. If the difference between two / three individual determinations is greater than 0.3%, a new determination is made and, if the difference between the values does not differ more than twice the standard repeatability deviation, the average value of the closest values of the two / three determinations taken into account.
    [0126] However, in the event that four determinations have to be made at once because it is a fly ash, the result of the test will be the average of these four determinations with the condition of complying with the standard repeatability deviation of the method and corresponding reproducibility when established, like all other natural and artificial pozzolans regardless of the number of determinations that must be made.
    [0127] - Drying of the initial sample: the sample of natural or artificial pozzolan, taken according to the UNE 80401 standard, is dried in an oven at 105 ± 5 ° C for 2 hours, according to the UNE 80220 standard.
    [0128]
    [0129] For the realization of the various chemical reactions and analytical determinations, only reagents of recognized analytical quality (chemically pure for analysis) as well as distilled water (H2O dda.) Will be used:
    [0130]
    [0131] - Calcium hydroxide: Ca (OH) 2 (stored in a tightly closed bottle or container).
    [0132]
    [0133] - Sodium chloride: NaCI (dried at 105 ° C).
    [0134]
    [0135] - Additional chemical reagents: In addition to the chemical reagents referred to, those of the Mohr method are required, with the exception of the special reagents “Suspension of aluminum hydroxide” (dissolve 125 g of potassium aluminum sulfate, AIK (SO4) -12H2O , or of aluminum-ammonium sulfate, AINH4 (SO4) -12H2O, in 1 liter of H2O dda.), and “Hydrogen peroxide, H2O2, 30%”, because the filtered liquids of the HB-SA of the pozzolana very they will hardly be colored or contain sulfides, sulphites or thiosulfates, respectively. However, since these filtered liquids will all be quite basic for the amount of residual Ca (OH) 2 that still had to be left over from the initial amount that had to be initially dosed in justified excess to the pozzolana for its basic and saline hydration Accelerated (HB-SA), their corresponding excess or residual NaCI content can also not be directly entitled to the initial amount that had to be dosed also, for which before proceeding to the titration of its corresponding chloride content leftovers still (expressed in mg / l, according to UNE 77041), the volumetric sample of said filtered liquids must be made to have a pH between 7 and 10, which is achieved again according to said UNE 77041, adjusting it with the necessary drops of nitric acid, HNO3, diluted (1:20) according to manuals and / or rules of good practice in this matter by other authors. The quantity of liquids filtered to title or problem solution of chlorides must have a neutral or near neutral pH, since if the pH «7 would dissolve the Ag2CrO4 and make it difficult to detect the endpoint of the titration, while a pH» 7 would cause precipitation of the Ag + cation as AgOH (silver hydroxide) brown and an error would be made.
    [0136]
    [0137] Below are the necessary devices to perform and implement the method:
    [0138]
    [0139] - Analytical balance (s), with an accuracy of ± 0.0001 g.
    [0140]
    [0141] - Stove (s), which can be regulated from 105 ° C to 110 ° C, with an accuracy of ± 5 ° C.
    [0142]
    [0143] - Thermostatic bath, (or other incubator chamber), which can be adjusted from 30 to 50 ° C, with an accuracy of 0.05 ° C, equipped with a platform of magnetic multi-agitators with the appropriate number of seats with continuous speed regulation (rpm)
    [0144] - Bottles with a tight seal, 250 ml capacity (Erlenmeyer flask made of alkali resistant glass or polyethylene but with a tight seal in any case). - Magnetic stirrers, resistant to the alkaline environment, adapted for the previous bottles.
    [0145] - Desiccator (s), provided with a key, with the desiccant gel with a moisture indicator. - Filter papers, fine pore 12 cm in diameter, free of ashes.
    [0146] - Vacuum equipment.
    [0147] - Büchner funnel, 9 cm in diameter.
    [0148] - Kitasato flask, 250 ml.
    [0149] - Volumetric glass material, analytical precision.
    [0150] - Glass material, the usual one of a chemical analysis laboratory.
    [0151] - Sieve, 44 pm mesh light.
    [0152] - Agate ball mill.
    [0153] - Platinum crucible, 50-60 ml.
    [0154] The wet chemical analysis method itself to determine the reactive alumina content, AhO3r - (%), of the natural and artificial pozzolans, object of the present invention, is developed in the following steps:
    [0155] Prior operating procedure
    [0156] i. Sample preparation
    [0157] The initial dry sample of the pozzolana is sprayed in an agate mortar until all of it passes through the 44 pm sieve.
    [0158] The sample of pozzolana is stored in an airtight desiccant container, thus avoiding exposure to the atmosphere.
    [0159] The initial sample should be analyzed in accordance with UNE-EN 196-2 (or ASTM C311) to obtain its total chemical composition, in mass%.
    [0160] ii. Dosage of stoichiometric and excess amounts of Ca (OH) 2 and NaCI. The stoichiometric and excess amounts of Ca (OH) 2 and NaCI that each pozzolan needs are dosed using the following mathematical expressions or models, using the corresponding values, in mass percent, that have been previously determined to the original pozzolana:
    [0161]
    [0162]
    [0163]
    [0164] Excess MNaCI = 0.01 • m1 • (1,146 • A 37,986 - 1.65 • Cl ')
    [0165]
    [0166] Where:
    [0167]
    [0168] m1 is the initial mass of pozzolan sample needed for the test, in g.
    [0169]
    [0170] A is the total AhO3 content of the pozzolan, determined by UNE-EN 196-2 (or ASTM C311), in% by weight.
    [0171]
    [0172] F is the total Fe2O3 content of the pozzolan, determined by UNE-EN 196 2 (or ASTM C311), in% by weight.
    [0173]
    [0174] S is the total SiO2 content of the pozzolan, determined by UNE-EN 196-2 (or ASTM C311), in% by weight.
    [0175]
    [0176] M is the total MgO content of the pozzolan, determined by UNE-EN 196-2 (or ASTM C311), in% by weight.
    [0177]
    [0178] CI- is the total chloride content of the pozzolan, determined by UNE-EN 196-2 (or ASTM C311), in% by weight.
    [0179]
    [0180] iii. Basic Hydration and Accelerated Saline (HB-SA) of the pozzolana.
    [0181]
    [0182] The basic hydration time and accelerated saline (HB-SA) for each pozzolan has been determined before also by the UNE-EN 196-5 Standard, adapted for this other purpose, with a number of test ages greater than those regulated by the In force Instruction for the reception of RC-16 cements, even up to 28 days when necessary, it will surely be the majority of cases. For this determination, a Portland cement type CEM I 42.5R with high C3A content (%) must be used, so that its corresponding Na2Oeq content. be greater than 0.60% without difficulty.
    [0183]
    [0184] If the pozzolan complies with said pozzolanicity test at the age of 1 and / or 2 days it is indicative that at the age of 7 days it must have already generated and developed all the pozzolanic activity it is capable of, so in the case of the present method 7 days is also the appropriate age, in principle, to be applied in this previous determination as time of HB-SA of the pozzolana within which is the chemical reaction, proper, of formation and precipitation of Friedel salt for the content of, AhO3 r ~ of the pozzolan that is to be determined, but not vice versa; although and as said HB-SA must be carried out in duplicate or triplicate at least, one HB-SA of both duplicate or triplicate will last 7 days while the other or other two will last 14 days. And if the standard deviation of repeatability of the results obtained in any case at both ages is <0.3%, HB-SA will be terminated, so that the value of the A ^ O3r “content of the pozzolana will be the average value of these two determinations or three, but otherwise and if it were necessary to know in addition to said content as soon as possible, HB-SA will be repeated once more from the pozzolana until the age of 21 days, which would have justified then having started it in quadruplicate, and with the new result that the last of the last tripled that it was not determined by not having met the first two values obtained its standard deviation of repeatability at 14 days of age, and that its HB-SA was therefore continued until the age of 21 days, its new arithmetic mean is obtained, and so on until the age of 28 days if necessary, at which in any case the HB-SA will end and, consequently, the trial, in which case and at the beginning it should have been done in six-fold. On the other hand, if such speed is not needed in knowing the value of the content of AhO3r_ of the pozzolana, the HB-SA until the age of 21 days would be replaced without more than that of 28 days and the value of the content of AhO3r “of the Puzolana will finally be the average value of these last two determinations, made at the common age of 28 days, to ensure that the dissolution and leaching of the total AhO3r_ content of the analyzed pozzolana has been completed in any way and in any case. Lastly, and in the case of similar fly ash and natural pozzolanas in hardness and / or composition, it will always be done in quadruplicate, the HB-SA must necessarily last 28 days with the relevant arithmetic consequences for its definitive determination with statistical analysis included.
    [0185]
    [0186] iv. Formation and Precipitation of Friedel salt of origin the content of AhO3r “of the pozzolan that is to determine:
    [0187]
    [0188] The amounts of Ca (OH) 2 and NaCI that the pozzolan needs to be analyzed, previously determined (by the mathematical expressions of step ii), are weighed and carefully poured into a clean and dry 50 ml beaker. Then, 100 ml of distilled water are taken, for example, by means of a clean and dry 50 ml burette and, in principle, the least possible amount of said solid chemical reagents is added to the vessel 100 ml of distilled water, to obtain the dispersion in it and dissolution of both chemical reagents.
    [0189]
    [0190] Next, 2,000 ± 0.005 g of pozzolana (m1), dried at (105 ± 5) ° C according to the UNE 80220 standard, with an accuracy of 0.0005 g, are weighed and carefully poured into a 250 ml airtight bottle that It is perfectly clean and dry too, to which is added little by little the distilled water left over from the initial 100 ml, stirring gently but constantly during the pouring process. Maintaining said agitation, the aqueous solution of Ca (OH) 2 and NaCl that had been prepared at the beginning is finally added to this last bottle.
    [0191] Finally, this last bottle, which contains the aqueous suspension of all solids, is placed in a thermostatic bath at a temperature of 40 ° C, with constant agitation (by means of a magnetic stirrer) and airtight seal during the adequate time of basic and saline hydration accelerated determined before, by the UNE-EN 196-5 standard, for each pozzolan.
    [0192] v. Filtration of the precipitate.
    [0193]
    [0194] Once the basic hydration and accelerated saline hydration time previously determined for the pozzolan being analyzed has elapsed, stirring stops. Then, the entire aqueous suspension resulting from the solids once at rest, is filtered under vacuum by means of a Büchner funnel, using a "fine" filter paper. (It is recommended to use two filter papers to ensure that the total amount of the solid part in suspension resulting from the HB-SA process has been retained).
    [0195]
    [0196] Once the filtering process is finished, a volume of the filtered liquids is taken (if the pozzolan has completed the Frattini test at the age of 1 day or 2, the volume of the filtered liquids taken will be 7 or 8 ml. change, if said test has been fulfilled at the age of 28 days, with 5 ml to be taken will be sufficient), by means of a clean and dry pipette or burette, and they are deposited in a clean and dry erlenmeyer of 250 ml capacity, to neutralize them before all their high basicity until a pH of 7 to 10 by means of the drops necessary nitric acid, HNO3, diluted (1:20). The quantity of liquids filtered to title or problem solution of chlorides, contained in the Erlenmeyer, are then titled according to the UNE 77041 standard, performing at the end of said titration the calculation of the results through the mathematical expression contained in said standard and expressing the Results in milligrams / liter (mg / l).
    [0197] [NaCI (mg / l) = Cl- (mg / l) x 1.65].
    [0198] Determination of the reactive aluminum sesquioxide (AhO3r_) content of the pozzolan by the new chemical wet analysis method.
    [0199] saw. Calculation and expression of the results.
    [0200]
    [0201]
    [0202]
    [0203] grs pozzolana is the initial mass of the pozzolan sample needed for HB-SA, in grams.
    [0204] grsNaCI (i) is the amount of stoichiometry NaCI plus the excess that is needed for the amount of previous pozzolan and that had been determined before by the equation in step ii, in grams.
    [0205] [Cl-] Mohr is the amount of excess chlorides actually, after HB-SA of the previous amount of pozzolana, determined by the UNE 77041: 2002 standard (Mohr method), in mg / l.
    [0206] Al2O3r “is the reactive alumina content of the pozzolan to be determined, in% by weight.
    [0207] vii. Repeatability of assay.
    [0208] The standard repeatability deviation is 0.3%.
    [0209] Description of a preferred embodiment
    [0210] A preferred embodiment of the chemical wet analysis method to determine the reactive alumina content of the natural and artificial pozzolans object of the present invention can be based on the following steps:
    [0211] Previous Operative Procedure
    [0212] i. Sample preparation
    [0213] The initial dry sample of the pozzolana is sprayed in an agate mortar until all of it passes through the 44 pm sieve.
    [0214] The sample of pozzolana is stored in an airtight desiccant container, thus avoiding exposure to the atmosphere.
    [0215] The initial sample should be analyzed in accordance with UNE-EN 196-2 (or ASTM C311) to obtain its total chemical composition, in mass%.
    [0216] ii. Dosage of stoichiometric and excess amounts of Ca (OH) 2 and NaCI. The stoichiometric and excess amounts of Ca (OH) 2 and NaCI that each pozzolan needs are dosed using the following mathematical expressions or models, using the corresponding values, in mass percent, that have been previously determined to the original pozzolana:
    [0217]
    [0218]
    [0219]
    [0220] m ca (OH) 2 junction - 0, 03 • A • mi • [1 0,01
    [0221] m _ = 0.01 NaCI in excess
    [0222] mNaCl in excess = 0.01 • m1 • (1.46 • A 37.986 - 1.65 • C1-)
    [0223] Where:
    [0224] m1 is the initial mass of pozzolan sample needed for the test, in g.
    [0225] A is the total AhO3 content of the pozzolan, determined by UNE-EN 196-2 (or ASTM C311), in% by weight.
    [0226] F is the total Fe2O3 content of the pozzolan, determined by UNE-EN 196 2 (or ASTM C311), in% by weight.
    [0227] S is the total SIO2 content of the pozzolan, determined by UNE-EN 196-2 (or ASTM C311), in% by weight.
    [0228] M is the total MgO content of the pozzolan, determined by UNE-EN 196-2 (or ASTM C311), in% by weight.
    [0229] CI "is the total chloride content of the pozzolan, determined by UNE-EN 196-2 (or ASTM C311), in% by weight.
    [0230] iii. Basic Hydration and Accelerated Saline (HB-SA) of the pozzolana.
    [0231] iv. Formation and Precipitation of Friedel salt of origin the content of AhO3r “of the pozzolan that is to determine:
    [0232] The amounts of Ca (OH) 2 and NaCI that the pozzolan needs to be analyzed, previously determined (by the mathematical expressions of step ii), are weighed and carefully poured into a clean and dry 50 ml beaker. Then, 100 ml of distilled water are taken, for example, by means of a clean and dry burette also of 50 ml and is added in principle to the vessel, with the amount of said solid chemical reagents inside, the smallest possible amount of said 100 ml of distilled water, to thereby obtain the dispersion in it and dissolution of both chemical reagents.
    [0233]
    [0234] Next, 2,000 ± 0.005 g of pozzolan (m1), dried at (105 ± 5) ° C according to the UNE 80220 standard, weighing 0.0005 g and are carefully poured into a 250 ml airtight bottle that is perfectly also clean and dry, to which the distilled water left over from the initial 100 ml is added little by little, stirring gently but constantly during the pouring process. Maintaining said agitation, the aqueous solution of Ca (OH) 2 and NaCl that had been prepared at the beginning is finally added to this last bottle.
    [0235] Finally, this last bottle, which contains the aqueous suspension of all solids, is placed in a thermostatic bath at a temperature of 40 ° C, with constant agitation (by means of a magnetic stirrer) and airtight seal during the adequate time of basic and saline hydration accelerated for each pozzolana.
    [0236]
    [0237] v. Filtration of the precipitate.
    [0238]
    [0239] Once the basic hydration and accelerated saline hydration time previously determined for the pozzolan being analyzed has elapsed, stirring stops. Then, all the aqueous suspension resulting from the solids once at rest, is filtered under vacuum by means of a Büchner funnel, using a "fine" filter paper (it is recommended to use two filter papers to ensure that the total amount of the solid part in suspension resulting from the HB-SA process).
    [0240]
    [0241] Once said filtering process is finished, a volume of the filtered liquids is taken by means of a clean and dry pipette or burette, and they are deposited in a clean and dry erlenmeyer of 250 ml capacity, to neutralize them before all their high basicity up to a pH of 7 to 10 by the necessary drops of nitric acid, HNO3, diluted (1:20). The quantity of liquids filtered to title or problem solution of chlorides, contained in the Erlenmeyer, are then titled according to the UNE 77041 standard, performing at the end of said titration the calculation of the results through the mathematical expression contained in said standard and expressing the Results in milligrams / liter (mg / l). [NaCI (mg / l) = Cl "(mg / l) x 1.65].
    [0242]
    [0243] Determination of the reactive aluminum sesquioxide (AhO3r) content of the pozzolan by the new wet chemical analysis method.
    [0244]
    [0245] saw. Calculation and expression of the results.
    [0246]
    [0247]
    [0248]
    [0249]
    [0250] Where:
    [0251]
    [0252] grs pozzolana is the initial mass of the pozzolan sample needed for HB-SA, in grams.
    [0253]
    [0254] grsNaCI (i) is the amount of stoichiometry NaCI plus the excess that is needed for the amount of previous pozzolan and that had been determined before by the equation in step ii, in grams.
    [0255] [CI'jMohr is the amount of leftover chlorides actually, after HBSA of the previous amount of pozzolana, determined by the UNE 77041: 2002 standard (Mohr method), in mg / l.
    [0256] AhO3r is the reactive alumina content of the pozzolan to be determined, in% by weight.
    [0257] vii. Test repeatability with a typical repeatability deviation is 0.3%.
    权利要求:
    Claims (2)
    [1]
    1. Wet chemical analysis method to determine the reactive alumina content of natural and artificial pozzolans, characterized in that it comprises the following stages:
    Prior operating procedure
    i. Sample preparation
    The initial dry sample of the pozzolana is sprayed in an agate mortar until all of it passes through the 44 pm sieve.
    The sample of pozzolana is stored in an airtight desiccant container, thus avoiding exposure to the atmosphere.
    The initial sample should be analyzed in accordance with UNE-EN 196-2 (or ASTM C311) to obtain its total chemical composition, in mass%.
    ii. Dosage of stoichiometric and excess amounts of Ca (OH) 2 and NaCI. The stoichiometric and excess amounts of Ca (OH) 2 and NaCI that each pozzolan needs are dosed using the following mathematical expressions or models, using the corresponding values, in mass percent, that have been previously determined to the original pozzolana:

    [2]
    2. Wet chemical analysis method for determining the reactive alumina content of natural and artificial pozzolans, according to claim 1, characterized in that only reagents of recognized analytical quality are used for carrying out the various chemical reactions and analytical determinations (chemically pure for analysis) as well as distilled water (H2O dda.):
    - Calcium hydroxide: Ca (OH) 2 (stored in a tightly closed bottle or container).
    - Sodium chloride: NaCI (dried at 105 ° C).
    - Additional chemical reagents: In addition to the chemical reagents referred to, those of the Mohr method are required, with the exception of the special reagents “Suspension of aluminum hydroxide” (dissolve 125 g of potassium aluminum sulfate, AIK (SO4) -12H2O , or of aluminum-ammonium sulfate, AINH4 (SO4) -12H O, in 1 liter of H2O dda.), and “Hydrogen peroxide, H2 O2, 30%”, because the filtered liquids of HB-SA of the pozzolana will hardly be colored or contain sulphides, sulphites or thiosulfates, respectively. However, since these filtered liquids will all be quite basic for the amount of residual Ca (OH) 2 that still had to be left over from the initial amount that had to be initially dosed in justified excess to the pozzolana for its basic and saline hydration Accelerated (HB-SA), their corresponding excess or residual NaCI content can also not be directly entitled to the initial amount that had to be dosed also, for which before proceeding to the titration of its corresponding chloride content leftovers still (expressed in mg / l, according to UNE 77041), the volumetric sample of said filtered liquids must be made to have a pH between 7 and 10, which is achieved again according to said UNE 77041, adjusting it with the necessary drops of nitric acid, HNO3, diluted (1:20) according to manuals and / or rules of good practice in this matter by other authors. The quantity of liquids filtered to title or problem solution of chlorides must have a neutral or near neutral pH, since if the pH «7 would dissolve the Ag2CrO4 and make it difficult to detect the endpoint of the titration, while a pH» 7 would cause precipitation of the Ag + cation as AgOH (silver hydroxide) brown and an error would be made.
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