A carbon reduction additive specially used for low calcium cement

Abstract

The present invention provides a carbon reduction additive dedicated to low-calcium cement, which belongs to the technical field of cement production, and is made of the following raw materials in mass percentage: 15%-25% of mixed alcohol amine, 10%-15% of dispersed components, 10%-15% of organic acid salt, and the balance is water. The carbon reduction additive provided by the present invention is mainly for the clinker produced by low-calcium limestone, improves the hydration degree of low-calcium clinker, and can effectively improve the strength of cement at all ages; when producing cement, although the strength of cement clinker is low, more admixtures can still be added to achieve the purpose of reducing carbon emissions in cement production.

Description

Technical Field

[0001] The invention relates to the technical field of cement production, and in particular to a carbon reduction additive dedicated to low-calcium cement. Background Art

[0002] With the development of economy and the improvement of living standards, buildings are springing up like mushrooms after rain. Cement is indispensable in the construction of these buildings. Cement grinding aids are often used in the cement production process. Cement grinding aids are cement additives mainly composed of alcohols and alcohol amines, supplemented by inorganic substances such as sodium chloride and sodium thiocyanate. Its effective components have a promoting effect on cement strength. Adding cement grinding aids in cement production can reduce the amount of clinker by 3-4% and replace it with mixed materials.

[0003] However, the limestone minerals used in cement production are mined every year, and the high-grade (high CaO content) minerals are gradually reduced. Low-grade minerals have to be used in production, which will lead to a decrease in the strength of cement clinker. The performance of cement grinding aids is limited. Under the "dual carbon policy", it is difficult to further improve the strength of cement. Moreover, the components in cement grinding aids basically affect the acceleration of cement clinker hydration, and have limited effects on admixtures, especially low-activity admixtures. Therefore, when low-activity admixtures are added, they often cannot play their due role. Therefore, a carbon reduction aid dedicated to low-calcium cement is needed. Summary of the invention

[0004] The purpose of the present invention is to provide a carbon reduction additive dedicated to low-calcium cement to solve the technical problems mentioned in the background technology. The carbon reduction additive provided by the present invention is mainly for the clinker produced by low-calcium limestone, which can improve the hydration degree of low-calcium cement clinker, thereby improving the strength of cement, thereby increasing the amount of cement admixtures, and achieving the purpose of reducing carbon emissions in cement production.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A carbon reduction additive specially used for low-calcium cement is prepared from the following raw materials in percentage by mass: 15%-25% of mixed alcohol amine, 10%-15% of dispersed components, 10%-15% of organic acid salt, and the balance being water.

[0007] Furthermore, the mixed alcohol amine is a mixture of modified triisopropanolamine and diethanol monoisopropanolamine, and the mass ratio of the modified triisopropanolamine to the diethanol monoisopropanolamine is 1:1.5-2.

[0008] Furthermore, the modified triisopropanolamine is produced by reacting triisopropanolamine and dimethyl carbonate.

[0009] Furthermore, the modification process of the modified triisopropanolamine is generated by adding a reaction solvent to triisopropanolamine and dimethyl carbonate in a molar ratio of 1:1 under non-aqueous conditions, the reaction temperature is 40-80°C, the reaction time is 6-8h, a reflux condenser is installed, the reaction solvent is isopropanol, and the conversion rate is 75%-85%.

[0010] Furthermore, the dispersing component is one or more of xylitol, mannitol, sodium gluconate, sucrose, and yellow dextrin.

[0011] Furthermore, the organic acid salt component is organic acid salts such as sodium formate, calcium formate, sodium acetate, sodium citrate, etc.

[0012] Triisopropanolamine is a cationic quaternary ammonium salt. When grinding cement, it can repel volcanic ash admixtures through electrostatic action and selectively adsorb on clinker and slag admixtures to bring out greater activity of clinker. When low-calcium cement is hydrated, due to its low CaO content in clinker, hydration enters dormancy prematurely. The superposition of modified triisopropanolamine and diethanol monoisopropanolamine can achieve deep acceleration of hydration of low-calcium clinker in the early stage of hydration, thereby improving cement strength.

[0013] The function of the dispersed component is to complex the calcium ions adsorbed on the surface of the silicon-rich layer of cement particles in the early stage of cement hydration, thereby improving the hydration degree of cement, reducing the porosity of the hydration product, and improving the later strength of cement;

[0014] When cement is hydrated, the organic acid salt components can be adsorbed on the surface of active admixtures, increasing their pozzolanic reactivity and thus improving the later strength of cement.

[0015] The present invention has the following beneficial effects due to the adoption of the above technical solution:

[0016] The carbon reduction additive provided by the present invention is mainly aimed at the clinker produced by low-calcium limestone, which improves the hydration degree of low-calcium clinker and can effectively improve the strength of cement at all ages. When producing cement, although the strength of cement clinker is low, more admixtures can still be added to achieve the purpose of reducing carbon emissions in cement production. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail with reference to the embodiments and preferred embodiments below. However, it should be noted that many details listed in the specification are only for the purpose of enabling the reader to have a thorough understanding of one or more aspects of the present invention, and these aspects of the present invention can be realized even without these specific details.

[0018] A carbon reduction additive for low-calcium cement, comprising the following raw materials in percentage by mass: 15%-25% of mixed alcohol amine, 10%-15% of dispersed components, 10%-15% of organic acid salt, and the balance of water; the mixed alcohol amine is a mixture of modified triisopropanolamine and diethanol monoisopropanolamine, the mass ratio of the modified triisopropanolamine to the diethanol monoisopropanolamine is 1:1.5-2; the modified triisopropanolamine is generated by the reaction of triisopropanolamine and dimethyl carbonate; the modified triisopropanolamine is prepared ... The modification process of propanolamine is that triisopropanolamine and dimethyl carbonate with a molar ratio of 1:1 are added to a reaction solvent under non-aqueous conditions to react, the reaction temperature is 40-80°C, the reaction time is 6-8h, a reflux condenser is arranged, the reaction solvent is isopropanol, and the conversion rate is 75%-85%; the dispersed component is one or more of xylitol, mannitol, sodium gluconate, sucrose, and yellow dextrin; the organic acid salt component is organic acid salts such as sodium formate, calcium formate, sodium acetate, and sodium citrate.

[0019] Embodiment 1,

[0020] The invention relates to a mixed alcohol amine comprising 20%, a dispersed component comprising 15%, an organic acid salt comprising 10%, and the balance comprising water; the mixed alcohol amine being a mixture of modified triisopropanolamine and diethanol monoisopropanolamine, wherein the mass ratio of the modified triisopropanolamine to the diethanol monoisopropanolamine is 1:1.5; the modified triisopropanolamine is generated by the reaction of triisopropanolamine and dimethyl carbonate; the modified triisopropanolamine is generated by the reaction of triisopropanolamine and dimethyl carbonate in a molar ratio of 1:1 under non-aqueous conditions by adding a reaction solvent, the reaction temperature being 60°C, the reaction time being 7 hours, a reflux condenser being arranged, the reaction solvent being isopropanol, and the conversion rate being 80%; the dispersed components being xylitol and sodium gluconate, wherein the mass ratio of xylitol to sodium gluconate is 1:1, and the organic acid salt being sodium formate.

[0021] The CaO content of the limestone raw material used for low-calcium clinker is 43%. The 3-day compressive strength of the clinker is 26MPa, and the 28-day compressive strength is 53MPa.

[0022] Conventional P.O42.5 cement includes the following raw materials in percentage by mass: clinker 86%, desulfurized gypsum 3%, limestone 5%, basalt 3%, bottom slag 3%;

[0023] Comparative P.O42.5 cement includes the following raw materials in percentage by mass: clinker 80%, desulfurized gypsum 3%, limestone 7%, basalt 5%, bottom slag 5%;

[0024] The activity of basalt is about 68, the activity of bottom slag is about 70, conventional P.O42.5 without carbon reduction additive is used as blank sample, and P.O42.5 with one thousandth of carbon reduction additive is used as comparison sample. The grinding time is the same. The experimental data are shown in Table 1:

[0025] Table 1 Carbon reduction additive P.O42.5 cement small mill experimental data

[0026]

[0027] Example 2

[0028] The invention relates to a mixed alcohol amine comprising 15%, a dispersed component comprising 10%, an organic acid salt comprising 15%, and the balance comprising water; the mixed alcohol amine being a mixture of modified triisopropanolamine and diethanol monoisopropanolamine, wherein the mass ratio of the modified triisopropanolamine to the diethanol monoisopropanolamine is 1:2; the modified triisopropanolamine is generated by the reaction of triisopropanolamine and dimethyl carbonate; the modified triisopropanolamine is generated by the reaction of triisopropanolamine and dimethyl carbonate in a molar ratio of 1:1 with the addition of a reaction solvent under non-aqueous conditions, the reaction temperature being 40°C, the reaction time being 6 hours, a reflux condenser being arranged, the reaction solvent being isopropanol, the conversion rate being 75%, the dispersed components being xylitol and sucrose, wherein the mass ratio of xylitol to sucrose is 1:1, and the organic acid salt being calcium formate and sodium citrate, wherein the mass ratio of calcium formate to sodium citrate is 2:1.

[0029] The CaO content of the limestone raw material used for low-calcium clinker is 46.52%. The 3-day compressive strength of the clinker is 27MPa, and the 28-day compressive strength is 55MPa.

[0030] Conventional P.O42.5 cement includes the following raw materials in percentage by mass: 83% clinker, 4% desulfurized gypsum, 3% limestone, 6% black stone and 4% fly ash.

[0031] The activity of black stone is about 66, and the activity of fly ash is about 72.

[0032] The same cement, the same mass percentage of raw materials, a group without carbon reduction additives as a blank sample, a group with 1 / 1000 carbon reduction additives as a control sample, the same grinding time, the experimental data are shown in Table 2:

[0033] Table 2 Carbon reduction additive P.O42.5 cement small mill experimental data

[0034]

[0035] Example 3

[0036] The invention relates to a mixed alcohol amine comprising 25%, a dispersed component comprising 10%, an organic acid salt comprising 10%, and the balance comprising water; the mixed alcohol amine comprising a mixture of modified triisopropanolamine and diethanol monoisopropanolamine, wherein the mass ratio of the modified triisopropanolamine to the diethanol monoisopropanolamine is 1:1.5; the modified triisopropanolamine is generated by the reaction of triisopropanolamine and dimethyl carbonate; the modification process of the modified triisopropanolamine comprises the following steps: triisopropanolamine and dimethyl carbonate in a molar ratio of 1:1 are reacted with a reaction solvent under non-aqueous conditions, the reaction temperature is 80°C, the reaction time is 8h, a reflux condenser is arranged, the reaction solvent is isopropanol, and the conversion rate is 85%; the dispersed components are sugar alcohol, sucrose and yellow dextrin, wherein the mass ratio of xylitol, sucrose and yellow dextrin is 1:0.9:0.1, and the organic acid salts are sodium formate and sodium citrate, wherein the mass ratio of sodium formate to sodium citrate is 2:1.

[0037] The CaO content of the limestone raw material used for low-calcium clinker is 46.52%. The 3-day compressive strength of the clinker is 27MPa, and the 28-day compressive strength is 55MPa.

[0038] Conventional M32.5 cement includes the following raw materials in percentage by mass: clinker 62%, desulfurized gypsum 3.5%, limestone 13%, black stone 8.5%, slag 6%, volcanic ash 7%;

[0039] Comparative M32.5 cement includes the following raw materials in percentage by mass: 56% clinker, 3.5% desulfurized gypsum, 16% limestone, 8.5% black stone, 8% slag, and 8% volcanic ash.

[0040] The activity of black stone is about 66, the activity of slag is about 80, and the activity of volcanic ash is about 70.

[0041] Conventional M32.5 without carbon reduction additives was used as a blank sample. The M32.5 with one thousandth of carbon reduction additives added was compared with the M32.5 with the same grinding time. The experimental data are shown in Table 3:

[0042] Table 3 Carbon reduction additive P.O42.5 cement small mill experimental data

[0043]

[0044] Triisopropanolamine is a cationic quaternary ammonium salt. When grinding cement, it can repel volcanic ash admixtures through electrostatic action and selectively adsorb on clinker and slag admixtures to bring out greater activity of clinker. When low-calcium cement is hydrated, due to its low CaO content in clinker, hydration enters dormancy prematurely. The superposition of modified triisopropanolamine and diethanol monoisopropanolamine can achieve deep acceleration of hydration of low-calcium clinker in the early stage of hydration, thereby improving cement strength.

[0045] The function of the dispersed component is to complex the calcium ions adsorbed on the surface of the silicon-rich layer of cement particles in the early stage of cement hydration, thereby improving the hydration degree of cement, reducing the porosity of the hydration product, and improving the later strength of cement;

[0046] When cement is hydrated, the organic acid salt components can be adsorbed on the surface of active admixtures, increasing their pozzolanic reactivity and thus improving the later strength of cement.

[0047] The carbon reduction additive provided by the present invention is mainly aimed at the clinker produced by low-calcium limestone, which improves the hydration degree of low-calcium clinker and can effectively improve the strength of cement at all ages. When the carbon reduction additive is used in cement production, although the strength of cement clinker is low, more admixtures can still be added to reduce the carbon emissions of cement production.

[0048] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A carbon reduction additive specially used for low-calcium cement, characterized in that: The method comprises the following raw materials in percentage by weight: 15%-25% of mixed alcohol amine, 10%-15% of dispersed component, 10%-15% of organic acid salt, and the balance is water; The mixed alcohol amine is a mixture of modified triisopropanolamine and diethanol monoisopropanolamine, and the mass ratio of the modified triisopropanolamine to the diethanol monoisopropanolamine is 1:1.5-2; The modified triisopropanolamine is produced by the reaction of triisopropanolamine and dimethyl carbonate; The modified triisopropanolamine is prepared by reacting triisopropanolamine and dimethyl carbonate in a molar ratio of 1:1 under non-aqueous conditions by adding a reaction solvent, the reaction temperature is 40-80°C, the reaction time is 6-8h, a reflux condenser is arranged, the reaction solvent is isopropanol, and the conversion rate is 75%-85%.

2. The carbon reduction additive for low-calcium cement according to claim 1, characterized in that: The dispersing component is one or more of xylitol, mannitol, sodium gluconate, sucrose and yellow dextrin.

3. The carbon reduction additive for low-calcium cement according to claim 1, characterized in that: The organic acid salt components are sodium formate, calcium formate, sodium acetate and sodium citrate organic acid salts.

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