Inhibitor for relieving cement false setting as well as preparation method and application thereof

Abstract

The invention discloses an inhibitor for relieving cement false setting as well as a preparation method and application thereof. The inhibitor comprises the following components in parts by weight: 5-10 parts of a retarding component, 0.5-3 parts of a surface active component and 87-94 parts of a metal impurity component, the retarding component is selected from one or more of sodium tripolyphosphate, sodium hexametaphosphate, hydroxyethylidene diphosphonic acid, amino trimethyl phosphonic acid, ethylenediamine tetra (methylene phosphonic acid), pentasodium diethylene triamine penta (methylene phosphonic acid) and 2-phosphonobutane-1, 2, 4-tricarboxylic acid; the metal impurity component is monovalent or divalent metal sulfate. The inhibitor can effectively relieve / solve the problems that the flowing property of fresh concrete becomes poor and the viscosity is sharply increased due to cement false setting, the working performance of the concrete is kept stable, and it is guaranteed that the concrete is easy to construct.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and in particular relates to an inhibitor for alleviating false setting of cement, and a preparation method and application thereof. Background Art

[0002] Cement is an important component of the building material concrete, and the normal setting of cement is very important for its practical application. Cement false setting refers to the fact that cement hardens quickly without releasing a lot of heat shortly after mixing with water. The cement slurry can still recover its plasticity without adding water and re-mixing, but its fluidity is significantly weakened.

[0003] There are several reasons for the false setting of cement: (1) During the cement grinding process, the temperature will rise, usually above 110°C, and dihydrate gypsum (CaSO4·2H2O) will dehydrate to form hemihydrate gypsum (CaSO4·0.5H2O) and soluble anhydrous gypsum (CaSO4). The dissolution rate of hemihydrate gypsum is higher than that of dihydrate gypsum. In theory, it can better control the hydration of C3A. However, hemihydrate gypsum can dissolve faster than C3A, combine with water and transform back into dihydrate gypsum, forming a supersaturated solution and crystals of dihydrate gypsum, causing false setting of cement. (2) The false setting phenomenon is related to the alkali present in cement. For some cements with high alkali content, the potassium sulfate contained in it will react according to the following formula: K2SO4+CaSO4·2H2O=K2SO4·CaSO4·H2O+H2O. The resulting pseudo-gypsum crystals grow rapidly, which can also cause false setting.

[0004] Today, with the widespread use of commercial concrete, the problem of cement false setting has attracted more and more attention in the industry. Among them, JC / T602-2009 "Test Method for Early Setting of Cement" stipulates that when the needle penetration percentage is less than 50%, cement is judged to be early setting; if it can restore plasticity after stirring without adding water, it is judged to be false setting. The standard stipulates that the needle penetration of 5 minutes is the final needle penetration. In fact, many cement false setting occurs after 5 minutes. For example, hemihydrate gypsum begins to hydrate and crystallize in 5 to 6 minutes, and is basically completely hydrated into dihydrate gypsum in 30 minutes. The specific time of false setting is uncertain, and most of them occur before 30 minutes. At the same time, cement false setting is directly related to the ambient temperature. Although it is qualified when leaving the factory, false setting may also occur due to the difference in ambient temperature during application. Therefore, the phenomenon of cement false setting often occurs.

[0005] Cement false setting does not undergo a true hydration reaction, and has no effect on the setting time and strength, but it will cause the working performance of fresh concrete to deteriorate. This is particularly serious with high-grade concrete. When high-grade concrete falsely sets, it will recover some fluidity after mixing, but the viscosity will increase significantly, seriously affecting the judgment of the fresh concrete's state out of the machine and the concrete pumping construction performance.

[0006] When the problem of false setting of cement is encountered in practical applications, the problem of false setting can only be alleviated / solved in the process or the stirring device. CN114474363A discloses a method for eliminating false setting of prestressed cement slurry, cement slurry and its false setting test method, which mainly eliminates false setting of prestressed cement slurry by adding mixing water and admixtures for a second time, and supplemented by secondary stirring, that is, adding water and admixtures in batches during stirring. CN112608095A discloses an expansion slurry for prestressed pipeline grouting and a preparation method thereof, which adopts a secondary stirring method to stir the slurry for a second time to reduce the adverse effect of early false setting of cement on the fluidity of the slurry, that is, after a few minutes of stirring, stir again after false setting occurs. However, the above-mentioned prior art has not found a solution to the problem of false setting of cement in terms of materials, and at the same time, adjusting the process or changing the stirring device during the production process will reduce production efficiency or increase production costs. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention provides an inhibitor for alleviating false setting of cement and a preparation method and application thereof, which can effectively alleviate / solve the problems of poor flow properties and sharp increase in viscosity of freshly mixed concrete caused by false setting of cement, maintain the stability of concrete working performance, and ensure that concrete is easy to construct.

[0008] The present invention is achieved through the following technical solutions:

[0009] An inhibitor for alleviating cement false setting, comprising the following components by weight: 5 to 10 parts of a retarding component, 0.5 to 3 parts of a surfactant component, and 87 to 94 parts of a metal impurity component;

[0010] Wherein, the retarding component is selected from one or more of sodium tripolyphosphate, sodium hexametaphosphate, hydroxyethylene diphosphonic acid, aminotrimethylphosphonic acid, ethylenediamine tetramethylenephosphonic acid, diethylenetriamine pentasodium methylenephosphonic acid, and 2-phosphonobutane-1,2,4-tricarboxylic acid;

[0011] The metal impurity component is a monovalent or divalent metal sulfate.

[0012] Preferably, the surfactant component is selected from one or more of cetyltrimethylammonium bromide, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, and cetylpentyldimethylammonium bromide.

[0013] Preferably, the metal impurity component is selected from one or more of lithium sulfate, copper sulfate, zinc sulfate, cadmium sulfate and magnesium sulfate.

[0014] Preferably, the retarding component is any one of sodium tripolyphosphate and hydroxyethylene diphosphonic acid or a mixture of the two.

[0015] Preferably, the surfactant component is any one of sodium dodecyl sulfate and sodium dodecyl sulfonate, or a mixture of the two.

[0016] Preferably, the metal impurity component is any one of lithium sulfate and zinc sulfate or a mixture of the two.

[0017] Furthermore, the preparation method of the above-mentioned inhibitor for alleviating cement false setting comprises the following steps:

[0018] The retarding component, the surfactant component and the metal impurity component are uniformly mixed according to the solid mass ratio to prepare a powder.

[0019] The above inhibitor for alleviating cement false setting is used in alleviating cement false setting. The inhibitor is added to cement in an amount of 0.5% to 2.0% of the total mass of the added cement. The false setting degree of cement is alleviated by controlling the adding ratio.

[0020] The beneficial effects of the present invention are as follows:

[0021] The components of the inhibitor for alleviating cement false setting of the present invention have good synergistic effects, and simultaneously affect the solubility and dissolution rate of hemihydrate gypsum, the crystal structure of dihydrate gypsum, and the solubility of potassium sulfate, inhibit different types of cement false setting, and can effectively alleviate / solve the problem of cement false setting, especially significantly improve the false setting of high-grade concrete; and there is no need to adjust the process or change the process of the stirring device during the production process, so it is suitable for popularization and application. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below with reference to specific embodiments.

[0023] An inhibitor for alleviating cement false setting comprises the following components by weight: 5 to 10 parts of a retarding component, 0.5 to 3 parts of a surfactant component, and 87 to 94 parts of a metal impurity component.

[0024] The retarding component is selected from one or more of sodium tripolyphosphate, sodium hexametaphosphate, hydroxyethylene diphosphonic acid, aminotrimethylphosphonic acid, ethylenediamine tetramethylenephosphonic acid, pentasodium diethylenetriamine pentamethylenephosphonic acid, and 2-phosphonobutane-1,2,4-tricarboxylic acid.

[0025] The surface active component is selected from one or more of hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, and hexadecylpentyldimethylammonium bromide.

[0026] The metal impurity component is selected from one or more of lithium sulfate, copper sulfate, zinc sulfate, cadmium sulfate and magnesium sulfate.

[0027] Determination of cement false setting: refer to the requirements of JC / T 602-2009 "Test Method for Early Setting of Cement", measure the percentage of pure slurry penetration after adding the cement false setting inhibitor in the following examples, test the initial penetration with reference to the standard, and select the final penetration of pure slurry at 6 time periods of 5min, 10min, 15min, 20min, 25min and 30min, and take the minimum penetration as the final penetration to calculate the percentage of penetration. Determine whether it is false setting according to the standard, that is, the penetration percentage is less than 50%, and the cement is judged to be early setting; if no water is added and the plasticity can be restored by stirring, it is judged to be false setting.

[0028] Three types of cement were selected for testing. Cement-1 is ordinary cement, and cement-2 and cement-3 are both pseudo-setting cements. The mineral composition of the cements is shown in Table 1 below. The components in Table 1 are in mass percentage.

[0029] Table 1 Mineral composition of three cements

[0030]

[0031] Example 1

[0032] A method for preparing an inhibitor for alleviating cement false setting, the specific steps are as follows:

[0033] (1) Weigh the following raw materials by mass:

[0034] (sodium tripolyphosphate + hydroxyethylene diphosphonic acid): sodium lauryl sulfate: lithium sulfate = 5:1:94.

[0035] Wherein, the mass ratio of sodium tripolyphosphate to hydroxyethylene diphosphonic acid is 1:1.

[0036] (2) Mix well and make into powder to obtain cement pseudo-setting inhibitor.

[0037] In this example, cement-2 was selected for testing, and the prepared cement pseudo-setting inhibitor was added to the cement paste, and the added amount was 1% of the total mass of the cement.

[0038] Example 2

[0039] A method for preparing an inhibitor for alleviating cement false setting, the specific steps are as follows:

[0040] (1) Weigh the following raw materials by mass:

[0041] (sodium tripolyphosphate + hydroxyethylene diphosphonic acid): sodium lauryl sulfate: lithium sulfate = 5:1:94.

[0042] Wherein, the mass ratio of sodium tripolyphosphate to hydroxyethylene diphosphonic acid is 1:1.

[0043] (2) Mix well and make into powder to obtain cement pseudo-setting inhibitor.

[0044] In this example, cement-2 was selected for testing, and the prepared cement pseudo-setting inhibitor was added to the cement paste, and the added amount was 2% of the total mass of the cement.

[0045] Example 3

[0046] A method for preparing an inhibitor for alleviating cement false setting, the specific steps are as follows:

[0047] (1) Weigh the following raw materials by mass:

[0048] (Sodium hexametaphosphate + ethylenediaminetetramethylenephosphonic acid): sodium dodecylsulfonate: cadmium sulfate = 5:3:92.

[0049] Wherein, the mass ratio of sodium hexametaphosphate to ethylenediaminetetramethylenephosphonic acid is 1:1.

[0050] (2) Mix well and make into powder to obtain cement pseudo-setting inhibitor.

[0051] In this example, cement-2 was selected for testing, and the prepared cement pseudo-setting inhibitor was added to the cement paste, and the added amount was 1% of the total mass of the cement.

[0052] Example 4

[0053] A method for preparing an inhibitor for alleviating cement false setting, the specific steps are as follows:

[0054] (1) Weigh the following raw materials by mass:

[0055] (sodium tripolyphosphate + hydroxyethylene diphosphonic acid): sodium lauryl sulfate: lithium sulfate = 5:3:92.

[0056] Wherein, the mass ratio of sodium tripolyphosphate to hydroxyethylene diphosphonic acid is 1:1.

[0057] (2) Mix well and make into powder to obtain cement pseudo-setting inhibitor.

[0058] In this example, cement-3 was selected for testing, and the prepared cement pseudo-setting inhibitor was added to the cement paste, and the added amount was 1% of the total mass of the cement.

[0059] Example 5

[0060] A method for preparing an inhibitor for alleviating cement false setting, the specific steps are as follows:

[0061] (1) Weigh the following raw materials by mass:

[0062] (Sodium hexametaphosphate + aminotrimethylphosphonic acid): (hexadecyltrimethylammonium bromide + sodium dodecylsulfonate): (lithium sulfate + zinc sulfate) = 5:1:94.

[0063] Among them, the mass ratio of sodium hexametaphosphate to aminotrimethylphosphonic acid, the mass ratio of hexadecyltrimethylammonium bromide to sodium dodecylsulfonate, and the mass ratio of lithium sulfate to zinc sulfate are all 1:1.

[0064] (2) Mix well and make into powder to obtain cement pseudo-setting inhibitor.

[0065] In this example, cement-2 was selected for testing, and the prepared cement pseudo-setting inhibitor was added to the cement paste, and the added amount was 1% of the total mass of the cement.

[0066] Example 6

[0067] A method for preparing an inhibitor for alleviating cement false setting, the specific steps are as follows:

[0068] (1) Weigh the following raw materials by mass:

[0069] (Sodium hexametaphosphate + aminotrimethylphosphonic acid): (hexadecyltrimethylammonium bromide + sodium dodecylsulfonate): (lithium sulfate + zinc sulfate) = 10:1:89.

[0070] Among them, the mass ratio of sodium hexametaphosphate to aminotrimethylphosphonic acid, the mass ratio of hexadecyltrimethylammonium bromide to sodium dodecylsulfonate, and the mass ratio of lithium sulfate to zinc sulfate are all 1:1.

[0071] (2) Mix well and make into powder to obtain cement pseudo-setting inhibitor.

[0072] In this example, cement-2 was selected for testing, and the prepared cement pseudo-setting inhibitor was added to the cement paste, and the added amount was 1% of the total mass of the cement.

[0073] Comparative Example 1

[0074] Weigh sodium dodecyl sulfate and lithium sulfate in a mass ratio of 1:99, mix well and prepare powder.

[0075] In this example, cement-2 was selected for testing, and the prepared powder was added to the cement paste, and the added amount was 1% of the total mass of the cement.

[0076] Comparative Example 2

[0077] Sodium tripolyphosphate and hydroxyethylidene diphosphonic acid are uniformly mixed in a mass ratio of 1:1 to prepare a powder.

[0078] In this embodiment, cement-2 was selected for testing, and the prepared powder was added to the cement paste, and the added amount was 0.05% of the total mass of the cement.

[0079] Comparative Example 3

[0080] In this example, cement-2 was selected for testing, and no inhibitor was added to the cement paste.

[0081] Comparative Example 4

[0082] In this example, cement-3 was selected for testing, and no inhibitor was added to the cement paste.

[0083] Comparative Example 5

[0084] In this example, cement-1 was selected for testing, and no inhibitor was added to the cement paste.

[0085] Test Example 1

[0086] Referring to the requirements of the above-mentioned JC / T 602-2009 "Test Method for Early Setting of Cement", the needle penetration percentage of the slurry after adding the cement pseudo-setting inhibitor of the present invention (Examples 1-5) was compared with that of the control group (Comparative Examples 1-5). The test results are shown in Table 2.

[0087] The rheological properties of cement paste for 5 to 30 min were tested by a rotational rheometer (R / S) at a controlled shear rate and 20°C. The water-cement ratio was 0.29. The rheological parameters of the cement pseudo-setting inhibitor (Examples 1-5) of the present invention were compared with those of the control group (Comparative Examples 1-5). The test results are shown in Table 2.

[0088] Table 2 Cement paste performance test results

[0089]

[0090] As shown in Table 2, Cement-1, as ordinary cement, does not have false setting phenomenon when the cement false setting inhibitor of the present invention is not added. However, Cement-2 and Cement-3 (false setting cements, i.e., containing components that can cause false setting phenomenon of cement) have obvious false setting phenomenon when the cement false setting inhibitor of the present invention is not added, but after adding the inhibitor of the present invention, the false setting phenomenon is significantly weakened or even disappears.

[0091] The yield stress and viscosity reflect the rheological properties of the slurry. When false coagulation occurs, the rheological properties of the slurry will change significantly, and the yield stress and viscosity will increase. When the false coagulation phenomenon weakens, the yield stress and viscosity will decrease. As shown in Table 2, the yield stress and viscosity values ​​of Examples 1-6 are generally lower than those of Comparative Examples 1-4. When there is no false coagulation at all, the yield stress and viscosity are both minimum. As shown in Table 2, the yield stress and viscosity of Comparative Example 5 are the minimum.

[0092] The embodiments described above are only some embodiments of the present invention, rather than all embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. The scope of protection of the present invention shall be subject to the scope required by the claims. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work shall fall within the scope of protection of the present invention.

Claims

1. An inhibitor for alleviating cement false setting, characterized in that: The components include the following by weight: 5 to 10 parts of a retarding component, 0.5 to 3 parts of a surfactant component, and 87 to 94 parts of a metal impurity component; Wherein, the retarding component is selected from one or more of sodium tripolyphosphate, sodium hexametaphosphate, hydroxyethylene diphosphonic acid, aminotrimethylphosphonic acid, ethylenediamine tetramethylenephosphonic acid, diethylenetriamine pentasodium methylenephosphonic acid, and 2-phosphonobutane-1,2,4-tricarboxylic acid; The metal impurity component is a monovalent or divalent metal sulfate.

2. The inhibitor for alleviating cement false setting according to claim 1, characterized in that: The surface active component is selected from one or more of cetyltrimethylammonium bromide, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, and cetylpentyldimethylammonium bromide.

3. The inhibitor for alleviating cement false setting according to claim 1, characterized in that: The metal impurity component is selected from one or more of lithium sulfate, copper sulfate, zinc sulfate, cadmium sulfate and magnesium sulfate.

4. The inhibitor for alleviating cement false setting according to claim 1, characterized in that: The retarding component is any one of sodium tripolyphosphate and hydroxyethylene diphosphonic acid or a mixture of the two.

5. The inhibitor for alleviating cement false setting according to claim 2, characterized in that: The surface active component is any one of sodium dodecyl sulfate and sodium dodecyl sulfonate or a mixture of the two.

6. The inhibitor for alleviating cement false setting according to claim 3, characterized in that: The metal impurity component is any one of lithium sulfate and zinc sulfate or a mixture of the two.

7. A method for preparing the inhibitor for alleviating cement false setting according to any one of claims 1 to 6, characterized in that: include: The retarding component, the surfactant component and the metal impurity component are uniformly mixed according to the solid mass ratio to prepare a powder.

8. A method for applying the inhibitor for alleviating cement false setting according to any one of claims 1 to 6, characterized in that: The inhibitor for alleviating cement false setting is added to cement in an amount of 0.5% to 2.0% of the total mass of the added cement.

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