MXPA99011839A - Admixture and method for optimizing addition of eo/po superplasticizer to concrete containing smectite clay-containing aggregates - Google Patents

Abstract

In the preparation of aqueous cement compositions containing a plasticizer, such as an EO/PO polymer-containing plasticizer, or EO/PO comb polymer-containing plasticizer, and further containing clay, such as a smectite clay, which expands when in contact with water, the step of providing an agent operative to modify the clay whereby the plasticizer absorbing capability of the clay is reduced. In exemplary methods of the invention, the plasticizer is an EO/PO (e.g., oxyalkylene) plasticizer and preferably an EO/PO comb polymer, and the clay-activity-modifiying agent may comprise an inorganic cation, an organic cation, a polar organic molecule capable of being absorbed by the clay, a clay dispersant (such as a polyphosphate), or a mixture thereof. For clay-activity-modifying agents which comprise a cation or a polar organic molecule, the agent is preferably added to the clay before water is introduced to the clay. For clay dispersant agents and some organic cations such as quaternary amines (which have a strong affinity for cationic exchange with the clay), the agent may be added before, during, or after water is introduced to theclay.

Description

MIXTURE AND METHOD TO OPTIMIZE THE ADDITION OF QE / OP SUPERPLASTIFIER IN CONCRETE CONTAINING AGGREGATES WITH ESMECTIC CLAY The present application is a continuation application in part based on the provisional patent application series No. 60 / 050,697 filed on June 25, 1997.

FIELD OF THE INVENTION The present invention relates to an improvement of the efficiency of the dosage in mixtures used in hydraulic cement compositions, such as Portland cement concrete, and more specifically, to the improvement of the efficacy of the polymeric additives that they have oxyalkylene, or the so-called "OE / OP" groups including the comb polymers having a bone, such as a carbon containing bone to which the oxyalkylene groups are attached.

GROUND OF THE INVENTION It is known to use so-called "OE / OP", or oxyalkylene polymers in hydraulic cement compositions such as Portland cement concrete. For example, in the Patent No. 5,393,343, which is fully incorporated herein by reference, Darwin et al. Describes an OE / OP type comb polymer useful as a superplasticizer or water reducer to maintain a high degree of settlement in concrete (e.g. fluidity) for a prolonged period of time. As used herein, the term "OE / OP" is synonymous with the term "oxyalkylene group" and serves as a convenient abbreviation for designating polyoxyalkylene groups (e.g., ethylene oxide / propylene oxide copolymers). Thus, for the purposes of the present, the term "comb polymer type OE / OP" means and refers to a polymer having a main chain, such as a carbon bone to which the carboxylate groups are attached. (which function as cement anchoring groups in the cement mixture) and pending groups such as ethylene oxide (OE) groups, propylene oxide (PO) groups and / or a combination of OE / OP groups. The pending groups can be ionic or non-ionic. Other examples of polymeric comb plastic superplasticizers • OE / OP type and water reducers. are shown in US Patent Nos. 4,946,904, 4,471,100, 5,100,984 and 5,369,198. "These patents describe comb polymers which are for example copolymers of polycarboxylic monomers such as maleic acid or anhydride and monomers containing polymerizable OE / OP such as the polyalkylene glycol monoalkyl ethers, et cetera.

Although the aforementioned OE / OP comb-like polymeric superplasticizers have been found to be effective, the efficacy of the dose (the amount of the polymer necessary to obtain the desired fluidity or plasticizing effect) tends to vary between different mixtures of cement or concrete.

SUMMARY OF THE INVENTION After a substantial investigation, it has been found that the problem in the variation of the efficiencies in the dosage of the OE / OP plasticizer can be attributed to the presence of certain inflatable clays, namely the ectites as mnotmorillonite of sodium, in the aggregate (sand) used to make the concrete or mortar. It has been found that negative interactions occur between the OE / OP superplasticizers and the mortar or concrete that contains the ectite clays. In theory, these clays are said to expand when they are initially wetted by the water in the mixture and in the extended state they absorb or trap the superplasticizer. These negative interactions cause a poor functioning of the mortar or fresh concrete and give rise to a poor response of the dosage. In addition, it has been found that various approaches are effective in restoring the dosing response of these superplasticizers. Effective methods generally include reducing or preventing clay expansion before clay contact and superplasticizer and include modifications of the mixing procedure, the addition of soluble calcium salts (for example calcium nitrite, calcium nitrate), and the addition of OE or OE / OP glycols to the mortar or fresh concrete. The combinations of these methods produce the best performance, especially for very rough sands of poor quality (clay carriers). In a broader sense, then, the invention includes the preparation of aqueous cement compositions containing a plasticizer and further containing clay which expands when in contact with water, and refers to providing an operative agent to modify the activity of clay. For example, the absorbent capacity of the OE / OP plasticizer in the clay is reduced. Preferably, the clay activity modifying agent is added to the clay before introducing the water to the clay, although in certain cases the agent can be added in any sequence and this has an affinity for the clay that exceeds the of the OE / OP plasticizer. In other exemplary methods, the clay is a smectite clay and the plasticizer consists of an OE / OP polymer (which includes the comb polymers having OE / OP portions in the main chain and / or in the pendant groups).

In other exemplary methods, the agent modifying the activity of the clay consists of an inorganic cation, an organic cation, a polar organic molecule capable of being absorbed by the clay, a dispersant of the clay (for example, a polyphosphate) or a mix of them. Preferably, when a cation or polar organic molecule is used, the agent modifying the activity of the clay is added to the clay before adding the water to moisten the clay in the preparation of the aqueous cementitious composition. Where the clay modifying agent is a clay dispersant, such as a polyphosphate or where the cation has a stronger affinity for cation exchange compared to the piastifier (such as organic cations). quaternary amines), then the agent can be intrc Jii? before, during or after the water is added -J the clay. The inventors c: .5- were that there are at least three possible mechanisms - to build the clay. One is by reducing the surface activity (or reactivity) of the clay, such as reducing the ability of the clay particles to absorb the OE / OP plasticizer. A second mechanism or mode of action is to reduce the viscosity of the clay that contributes to the global settlement of the concrete. It can be achieved by dispersing the clay (which separates the individual platelets from the clay) or by flocculating the clay (whereby the clay collapses or aggregates into a denser unit that produces less viscosity in the concrete mix) . A third mode of action is by prior absorption of the clay using a sacrificial agent. The invention further pertains to blends containing an OE / OP plasticizer and a clay activity modifying agent, as described above. Preferred blending compositions of the invention contain an OE / OP plasticizer, preferably an OE / OP comb polymer (with OE / OP groups in the main chain and / or in pendant groups) and a dispersant of the clay, as be polyphosphate, or an organic cation having a strong affinity for clay such as a quaternary amine, a polymer containing OE / OP (which is different from the OE / OP plasticizer dosed in the cement mixture), or mixtures thereof. same. Other advantages and features of the invention may be more apparent from the following detailed description. Detailed description of the exemplary embodiments The term "cement composition" as it may be used herein refers to pastes, mortars, slurries such as the binder grouts of oil wells, and concrete compositions containing a cement binder. hydraulic. The terms "paste", "mortar" and "concrete" are technical terms: pastes are mixtures composed of a hydraulic cement binder (usually, but not exclusively, Portland cement, Masonry cement or Mortar cement and can also include limestone, hydrated lime, ash dust, blast furnace slag, and fumes of silica or other materials commonly included in these cements) and water; mortars are pastes that additionally include fine aggregates, and concretes are mortars that also include coarse aggregates. The cement compositions tested in this invention are formed by mixing the necessary amounts of certain materials, for example, a hydraulic cement, water and fine or coarse aggregate, such as that applicable to make the specific cement composition to be formed. The term "clay" as used in the present invention refers specifically to 2: 1 clays which are usually swellable, absorbent clays often labeled as smectites, mont orillonite, illite, hectorite or BENTONITE commercially available. . It is also contemplated that volcanic ash and amorphous clays will also be included in absorbent materials considered within the definition of "clay". The inventors "are interested in the aforementioned 2: 1 clays (and not in clays 1: 1 such as kaolin clay which is not usually considered as inflatable clays.) Problematic clays 2: 1 (e.g., smectite) are present in certain arenas, and this is what the inventors have surprisingly found to be the cause of the absorption problem of the OE / OP plasticizer which they have solved by the invention described herein. The invention presents this proposal specifically for use and increase the efficiency in the dosing of polymeric OE / OP plasticizers. This includes polymers having oxyalkylene (or OE / OP) constituents, including but not limited to "comb" polymers having OE / OP constituents located in the main chains and / or in the pending groups. The OE / OP comb polymers were specifically tested in the present invention, and were most frequently acrylic polymers or copolymers thereof, which are imitated, as shown in U.S. Patent No. 5,393,343 assigned to W. R. Grace &; Co.-Conn. and is incorporated herein by reference. These plasticizers are marketed under the brand name "ADVA®". The ADVA® comb polymer (specifically polyacrylic acid) is prepared by grafting a polyoxyalkyleneamine onto a polycarboxylic acid backbone (amidation / imidation reaction). Another comb polymer (containing OE / OP groups) tested was the type obtained by polymerization of maleic anhydride and an ethylenically polymerizable polyalkylene, as prepared in the Patent No. 4,471,100, the entire description of which is incorporated herein by reference. This product is marketed under the brand name "MALIALIM". Both commercial products are sold in the form of metal salts formed by the final reaction of the polymers with a base such as sodium or calcium hydroxide. It is also contemplated that the invention may increase the efficiency of the dosing of OE / OP plasticizers that do not have a comb structure (i.e., the main chain with the pendant groups), but which may have a linear or branched structure, or other structures. In the tests carried out, various cement compositions, specifically concrete samples with Portland cement were separated containing the normal amount of cement, water, stone and sand. To these mixtures were added variable amounts of the comb polymer OE / OP "ADVA®" described above. The efficiency of the polymer dosage was determined by measuring the flow and settlement (ASTM procedure) of each of the mixtures. Test samples prepared using sand from the southwestern United States, CB Rilite sand from Reno, Nevada, ("CB") and sand from Placitas de Albuquerque, New Mexico ("MI"), showed poor efficacy in dosing. It was found that the replacement of the laboratory sand (from Kane-Perkins in Milton, NH) to the CB Rilite sand and the WMI Placitas sand improved the effectiveness of the dosage. This operation was confirmed in mixtures of microconcrete and mortar. That is, replacing the Kane-Perkins laboratory sand for CB or WMI sand produced substantially higher flow and settlement values. After analyzing the CB and WMI sands, it was found that both sands contained smectite clay. In parallel experiments it was found that the addition of sodium montmorillonite '(a clay sr. Citrate) to the Kane-Perkins sand resulted in mortar with poor fluidity. Additional tests of other clays showed that the hectorite, another type of smectite clay, also predicted the operation of the mortar, and that the kaolinite was different from smectite (for example 2). : 1), not an adverse effect on performance The poor performance observed for the mortar or concrete that had the ADVA® superplasticizer and the carrier sands and clay was also demonstrated for other OE / OP superplasticizers. It was found that other commercially available OE / CF superplasticizers (eg MALIALIM AKM 1511), caused a similar drastic reduction in the flowability of the mortar containing smectite clay, based on these data and previous tests, it appears that the Negative interactions with smectite clays can be attributed to a range of OE / OP plasticizers and not only ADVA® superplasticizers, after discovering the interactions between the smectite clays and the OE / OP superplasticizers in mortar and concrete, significant efforts were focused on trying to remedy the problem. Mainly three different effective approaches were found in the restoration of the effectiveness of the OE / OP polymers in the mortar or concrete with a smectite clay content. First, the addition of operant agents to reduce the absorptive capacities of OE / OP of the clay contained in the clay-bearing aggregate, whose agents were added to the mortar mixtures before the addition of the superplasticizer, effectively improved the performance of the mortars. containing smectite clays and the ADVA® superplasticizer. Where the agent consisted of a glycol, such as polyethylene glycol ("PEG"), it was observed that the PEG of higher molecular weight produced a significant improvement in the flow of the mortar. The use of glycol with a content of ethylene oxide and propylene glycol was also found effective in improving the flow of the mortar. Thus, it was demonstrated that the OE and OE / OP materials can be used to partially restore the operation of the mortar. In any case, it is very likely that these compounds are absorbed on the surface of the clay, thus satisfying some of the affinity of the clays for the absorption of the polymer, and essentially acting as a "sacrificial lamb". A second method found to be extremely effective was the restoration of the efficiency of the OE / OP plasticizer dosage through the modification of the mixing procedures of the mortar or concrete. In particular, it was found that the order of addition of the materials in a mixer can have an effect on the operation of the mortar or concrete with a content of OE / OP superplasticizer (for example the ADVA® superplasticizer) and the clay carrier sand. It was found that by delaying the addition of the clay-bearing sand (until after all other materials had been added) the efficiency of the ADVA® superplasticizer dosage could be restored. In addition, it was found that only a small portion of cement is initially necessary to activate this effect. The essential element of this discovery is that the cement (in some quantity) must be present in the mixture before or at the same time that the clay-bearing sand comes into contact with the mixing water. If this order of addition can be ensured, the effectiveness of the dosing of the OE / OP superplasticizers in the mortar or concrete can be significantly improved regardless of the presence of the smectite clays. It was also found that changing the order of addition during mixing can reduce the total water demand of the mortar (regardless of the superplasticizer). Therefore, when treating the mortar containing conventional condensed naphthalene / formaldehyde plasticizer in an identical manner to the mortar containing the ADVA® superplasticizer, the operation of each mixture can be improved. If this modified mixing method is used for the aforementioned mortars (each containing 0.6% clay), it is possible to improve the efficiency of the new dosage. When smaller dosages of clay are used, the effectiveness of the dosage can be increased. It was also observed that the mortar (with clay carrier sand) that does not contain superplasticizer can be improved using the modified mixing method, ie the fluidity of the reference mortar can also be improved with this mixing technique. Finally, it was found that a promising method is the addition of soluble calcium salts (preferably calcium nitrate) before the introduction of the clay-bearing sand. It was shown that the dosage response of the OE / OP superplasticizer can be restored with this method. It was further found that the addition of calcium nitrate directly to the clay-bearing sand was more effective than the addition of calcium nitrate to the water in the mixture. It is further considered that soluble potassium salts may also be suitable for the invention. When studying the behavior of an extremely poor quality sand with a smectite content (from Reno), it was found that the change in the order of addition of the materials was not enough to remedy the malfunction of the mortar containing the ADVAü superplasticizer. . Additional work showed that for cases like this sand of poor quality, it is sometimes necessary to combine the three methods described above (ie, the modified mixing method + polyethylene glycol + calcium nitrate). This combined method produces optimal performance and demonstrated a combined synergistic effect. It was further demonstrated that an optimal mixture of polyethylene glycols of different molecular weights can be determined which produces the most beneficial flow properties. furtherOther exemplary methods of the invention may include agents that do not need to be introduced preferentially before the addition of a plasticizer or the addition of water to the clay. For example, the use of a polyphosphate, such as sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate and sodium acid pyrophosphate, or a mixture thereof, does not require the addition of a superplasticizer after the agent proposed for use. reduce the absorptive capacities of OE and / or OP of the clay. Exemplary clay activity modifying agents that are suitable for use in the invention can be classified as follows. Exemplary multivalent, inorganic cations which are useful for modifying the activity of the clay include multivalent cations, such as calcium, magnesium, aluminum, hir or a mixture thereof. The calcium nitrite and calcium nitrate are preferred inorganic cations, jcao already mentioned, which can also be used: cr. oxyalkylenes such as (poly) ethylene glycol (PEG). Exemplary modifying agents of clay activity also include monovalent inorganic cations such as K +, NH. , Is', Rb +, Fr +, or a mixture thereof). Among these, potassium nitrate is preferred. Other exemplary clay activity modifying agents include organic cations, such as a quaternary amine, (poly) quaternary amine, an amine oxide, or a mixture thereof. The term "organic cation" as used herein refers to any exchange agent (any compound capable of exchanging interlamellar cations associated with 2: 1 clays (eg, smectite) containing: (a) an organic group attached to a cation salt group selected from phosphonium, pyridinium, sulfonium and quaternary ammonium (including polyquaternary ammonium), or (b) an organic compound containing a single cationic amine salt group and no other amino group. the exchange agents in any category can be a polymeric group, Included among the organic cations which can be used in the present invention are amphoteric materials (eg, amphoteric surfactants) Organic cations which are considered useful in the invention include, but are not limited to, hexadecyltrimethylammonium, methyltriphenylphosphonium, benzyltriphenylphosphonium and tensoact such as N, N-dimethyl-l-hexadecanamine oxide (commercially available from Akzo Novel Chemical, Chicago Illinois, under the trademark Aromox® DM-16, and N, N, N ', N' chloride, N '-pentamethyl-n-bait-1,3, propandiammonium (also commercially available from Akzo under the trademark Duoquad® T-50). Other exemplary organic cations considered useful in the invention include fatty amines (of C 2 -C 18) and amino acids (for example lysine). The organic cation modifiers of the activity of the clay are preferably provided in aqueous solution, for safety and low cost. However, in some cases, such as when it is desired to use an organic cation agent in the form of a commercially available organic surface active agent, the organic cationic agent can be provided in an organic solvent. A preferred organic cation is a quaternary amine, such as a (poly) quaternary amine in combination with polyethylene glycol (PEG), a combination that facilitated the improved performance of the OE / OP plasticizer that was better than using the quaternary amine or PEG alone The use of a quaternary amine having a bound polyoxyethylene functional group was also found to be more effective than other quaternary amines without polyoxyethylene attached, particularly when it was added at the beginning of the mixing cycle. Other exemplary clay activity modifying agents include polar organic molecules that can be absorbed by clays (smectite type), such as an oxyalkylene (for example, ethylene and / or propylene glycols such as PEG), a crowned ether, a psvyl alcohol, a polyacrylic acid, a polymethacrylic acid, a polyacrylate, a polymethacrylate, a gluconate, a heptaglucsnate, a heptagluconic acid , a gluconic acid, a corn syrup or a mixture thereof. If the polar organic molecule is a polyacrylic acid, a polymethacrylic acid, a polyacrylate or a polymethacrylate, then the molecular weight should be 2,000 or less. These are preferably added before the plasticizer of type OE / OP is introduced into the clay. This can be done by having the agent modifying the activity of the clay present before the water is added to the clay with which it is plasticizer type OE / OP then it is put in chemical contact with the clay. It was found that certain clay modifying agents that have an affinity for clay stronger than the affinity of the OE / OP type plasticizer for clay, such as quaternary amines (for example polyquaternary amines), and polyphosphates can be added simultaneously with the OE / OP plasticizer or before the OE / OP plasticizer is added. Another agent modifying the activity of the exemplary clay consists of a polyphosphates, such as metaphosphate (sodium metaphosphate), a tripolyphosphate (for example sodium tripolyphosphate), a pyrophosphate (for example sodium pyrophosphate, sodium acid pyrophosphate) , or a mixture thereof. Still other exemplary methods and mixtures of the invention consist in using a cement dispersant, such as a lignosulfate, a hydroxylated carboxylate, a carbohydrate or mixtures thereof, in addition to the dispersant of the clay. Experts in cement and concrete techniques will understand that the amount of the clay-modifying agent (either the cationic, polar, organic molecule that can be absorbed by the clay, or a dispersing variety of the clay) will vary. according to the nature of the sand, the amount and nature of the plasticizer to be dosed, the particular addition sequence of the components used, the mixing conditions and other factors. It is considered that a range such as 0.005% s / s (percent by weight based on solid cement) can be used up to 12% s / s, with a range of approximately 0.01-10.0% s / s being preferred. However, again the range depends on the nature of the conditions and nature of the mixing operation. A better understanding of the present invention can be more readily understood when the following examples are considered.

Example 1 A conventional plasticizer that does not have OE / OP groups, namely a sodium naphthalene sulfonate formaldehyde (NSFC) superplasticizer traded by. R. Grace & Co.-Conn. with the DARACEM® 19 brand, it was compared with an OE / OP plasticizer marketed by Grace under the ADVA® brand. The cement mixture was formulated with a content of 1100 g of Portland Type 1 cement with 2035 g of sand, and water was added. For mixtures # 1, # 3 and # 5, the amount of water was adjusted individually until the MC (micrccrecret) settlement of each mixture exceeded 120 mm; for mixtures # 2, # and # 6, the same amount of water corresponding to # 1, # 3 and # 5 was used for the purposes of determining the settlement. Settlement was measured by placing samples of cement / sand / plastific mixture in a cone and inverting the cone on a table to empty a cone-shaped sample, and measuring the descent - • :; the height of the cone. The cone size used was r-erium with JIS # A-1173 (cone height = 150 mm, super diameter: _r = 50 mm, lower diameter = 100 mm). First, the control test was performed to confirm that in the normal laboratory setting (Kane-Perkins, Milton, New Hampsmre) the OE / OP superplasticizer was three times or more as efficient in providing settlement.

The control samples were relatively unaffected by the laboratory sand, but the settlement of the samples containing the OE / OP plasticizer with smectite cl(Placitas sand (from Albuquerque, New Mexico, and the Rilite sand from CB Concrete, Reno Thus, surprisingly, it was found that the smectite-like clay-bearing aggregates decrease the efficiency of the OE / OP type plasticizer dosing The tests are summarized in Table 1 below.

Table 1 As shown in the table above, the effectiveness of the OE / OP plasticizer (measured in terms of providing settlements) was not affected by the ordinary laboratory sand, since approximately a third of the OE / OP plasticizer had the same settling efficiency. of the non-OE / OP plasticizer in the laboratory sand (Grace's ADVA® superplasticizer is typically about three times or more as effective as compared to plasticizer without OE / OP content). However, when sands containing smectite clay were used, the operation of the OE / OP superplastifier settlement decreased drastically.

Example 2 Samples were tested using standard laboratory sand but with hectorite clay (a smectite) to confirm that the decrease in the operation of the OE / OP superplastifier settlement was due to clay in the aggregate. The addition of water was similar to the previous example (hectorite was added at 2% based on the weight of the sand to the cement, and then the different plasticizers were added after a few seconds.) The NSFC-type plasticizer (DARACEM® 19) was compared with an amount equivalent to the operation of OE / OP plasticizer (ADVA®) The results are given in the following Table 2. It is observed that the OE / OP plasticizer (mixture # 8) suffered a decrease in the operation of the settlement that can be attribute to the presence of hectorite clay.

Table 2 Example 3 Another test was performed to determine the effect of the addition of an inorganic cationic salt to a mixture containing a sodium montmorillonite sand. To prepare the mixture, 0.6% (based on the weight of the sand) of sodium montmorillonite (a smectite clay) was added to the standard laboratory sand. In another sample, 0.5% by weight (based on cement weight) of calcium nitrate (Grace DCI®) was used, and microconcrete settlement tests were performed. Calcium nitrate was added to the clay before the OE / OP plasticizer was added to the clay. It was observed that the use of salt improves the effectiveness of the OE / OP plasticizer dosage. The results are shown in Table 3 below. Table 3 Example 4 Another series of samples were tested to illustrate the effects of organic cations on the efficacy of OE / OP dosing. To prepare the mixture, sodium montmorillonite (a smectite clay) was again added to standard laboratory sand mixtures, and this was prepared in the same manner as the previous examples. An organic cation, namely, cetyltrimethylammonium bromide (CTB) (0.04% s / s) was added to the mixture at the same time as OE / OP (ADVA®) was added (see mix # 11). Another organic cation, tetrabutylammonium bromide (TTB) (0.04% s / s) was also tested. Another example, lauryl dimethylamine oxide (LDAO) (0.04% s / s) was also tested. This was also added at the same time as the OE / OP plasticizer. In both cases, the effectiveness of the OE / OP plasticizer dosage was increased by the presence of the organic cation when compared to the above # 9 mixture. The results are shown in the operation of the settlement in Table 4 below, where the settlement figures were restored to approximately 110 mm.

Table 4 Example 5 Another series of samples were tested to illustrate the effects of a polar molecule on the effectiveness of the dosage of "1". To prepare the mixture, scamor montmorillonite-smectite clay-was again added to standard laboratory sand re-lac, and this was repaired similar to the previous examples. An organic p-lar molecule, namely, polyethylene glycol (PEG) (approximate molecular weight 1000) (0.04% s / s) was added to the mixture before the OE / OP (ADVA®) was added. Another polar molecule, namely, polyvinyl alcohol (grade BP-03 prepared by ChemComm, Inc. of Katy, Texas) and a crowned ether (from Aldridge Chemicals) were also tested. In each of these cases, the dosage efficiency of the OE / OP plasticizer was restored, when compared to the OE / OP alone (see mixture # 9 above). The results are shown in the operation of the settlement in Table 5 below.

Table 5 Example 6 Another series of samples were tested to illustrate the effects of a polyphosphate on the efficacy in the dosing of OE / OP. To prepare the mixture, sodium montmorillonite (a smectite clay) was again added to the standard laboratory sand mixtures, and it was prepared similar to the previous examples. A polyphosphate, sodium hexametaphosphate (SHMP) (0.10% s / s) and a calcium lignosulfonate (CLS) (0.15% s / s) was added to the mixture at the same time that OE / OP (ADVA®) was added. Other polyphosphates were tested, such as sodium tripolyphosphate (STP) and sodium acid pyrophosphate (SAPP). All phosphates were obtained from Solutia, Inc. of St. Louis, Missouri. The efficiency in the dosing of the OE / OP was thus improved (compared to the OE / OP alone) (see mixture # 9 above). The results are shown in Table 6 below.

Table 6 The aforementioned examples are provided par. illustrative purposes only and are not suggested to limit the scope of the invention.

Claims (15)

1. CLAIMS 1. In the preparation of aqueous cement compositions containing a plasticizer and also contain clay that expands when in contact with water, the step of providing an operative agent to modify the activity of the clay.
2. 2. The method of claim 1, wherein the clay is a smectite clay.
3. 3. The method of claim 1, wherein the plasticizer consists of an OE / OP polymer.
4. 4. The method of claim 3, wherein the plasticizer consists of a comb polymer OE / OP. The method of claim 3, wherein the operative agent for modifying the clay consists of an inorganic cation. 6. The method of claim 5, wherein the inorganic cation is a multivalent. 7. The method of claim 6, wherein the inorganic multivalent cation consists of calcium, magnesium, aluminum, iron or a mixture thereof. The method of claim 6, wherein the inorganic multivalent cationic agent consists of calcium nitrite, calcium nitrate or a mixture thereof. 9. The method of claim 8 further comprises an oxyalkylene molecule having a different formula of the OE / OP plasticizer dosed in the aqueous cement composition. The method of claim 6, wherein the inorganic multivalent cation is present when water is added to the clay. The method of claim 5, wherein the inorganic cationic agent consists of a monovalent cation. The method of claim 11, wherein the inorganic monovalent cation consists of K +, NH +, Cs +, Rb +, Fr + or a mixture thereof. 13. The method of claim 12, wherein the inorganic monovalent cation is present when water is added to the clay 14. The method ie claim 3, wherein the agent consists of an organic o.tli. method of claim 14, wherein the organic cation consists of: a) an organic group attached to a cationic salt group selected from phosphonium, pyridinium, sulfonium, quaternary ammonium or ammonium (poly) quaternary, amine oxide or (b) an organic compound consisting of a single cationic amine salt group 16. The method of claim 15, wherein the organic cationic agent consists of a (poly) quaternary amine. claim 15, wherein the amine further consists of an oxyalkylene group 18. The method of claim 15, wherein the organic cation is present when water is added to the clay 19. The method of claim 3, wherein the operative agent for m odificar the activity of the clay consists of a polar organic molecule able to be absorbed by the clay. The method of claim 19, wherein the agent modifying the activity of the clay, polar organic molecule consists of an oxyalkylene, a crowned ether, a polyvinyl alcohol, a polyacrylic acid, a pslmethacrylic acid, a polyacrylate, a polymethacrylate , a gluconate, a heptagluconate, a heptagluconic acid, a gluconic acid, a corn syrup or a mixture thereof. The method of claim 20, wherein the clay activity modifier, polar organic molecule, consists of an oxyalkylene. 22. The method of claim 21, wherein the oxyalkylene consists of an ethylene glycol, a propylene glycol or a mixture thereof. 23. The method of claim 19, wherein the polar organic molecule capable of being absorbed by the clay consists of an oxyalkylene polymer having a molecular structure different from that of the plasticizer dosed into the aqueous cement composition that it feels prepared. The method of claim 19, wherein the organic molecule capable of being absorbed by the clay consists of an OE / OP comb polymer having pendant OE / OP groups with an average molecular weight of less than 1000. 25. The method of Claim 19, where the agent operative polar organic molecule to modify the clay is present when water is added to the clay. 26. The method of claim 3, wherein the operative for modifying the clay consists of a dispersant of the operating clay to reduce the ability of the clay to absorb the plasticizer. 29. The method of claim 26, wherein the clay dispersing agent consists of a polyphosphate. 30. The method of claim 29, wherein the dispersing agent of the polyphosphate clay consists of a hexametaphosphate, a tripolyphosphate, a pyrophosphate or a mixture thereof. 31. The method of claim 30, wherein the agent consists of a hexametaphosphate that is sodium hexametaphosphate. 32. The method of claim 30, wherein the agent consists of a tripolyphosphate which is sodium tripolyphosphate. 32 [sic]. The method of claim 30, wherein the agent consists of a pyrophosphate which is a sodium pyrophosphate, a sodium acid pyrophosphate, or a mixture thereof. 33. The method of claim 30 further comprises adding a cement dispersant consisting of a lignosulfonate, a hydroxylated carboxylate, a carbohydrate or a mixture thereof. 34. The method of claim 1, wherein the agent is present when water is added to the clay. 35. A cement composition consisting of a hydraulic cementitious binder, an OE / OP plasticizer, a clay carrier aggregate and an operative agent to modify the activity of the clay. 36. A mixture consisting of an OE / OP plasticizer and an operative agent to modify the activity of the clay.