A silicate cement carbonization early strength agent with negative carbon function and its preparation method and application

Abstract

The present invention discloses a carbonization early strength agent for silicate cement with negative carbon function and its preparation method and application. The early strength agent comprises the following components: Ca2SiO4-α' L 0~8 parts by weight of powder, 0~5 parts by weight of Ca3Al2O6-o powder, 0~5 parts by weight of CaO powder, wherein: the Ca2SiO4-α' L , Ca3Al2O6‑o respectively through K + The preparation method comprises the following steps: doping the Ca2SiO4-α' L The powder, Ca3Al2O6-O powder, and CaO powder are uniformly mixed with an anhydrous solvent to form a slurry, and the slurry is dried to obtain the early strength agent. The early strength agent of the present invention can not only effectively solve the problems of high pollution, high price, and poor effect over a long period of time in the prior art, but also enable cement to absorb CO2 in the air, thereby having a certain carbon capture function.

Description

Technical Field

[0001] The present invention relates to the technical field of cement early strength agent preparation, and in particular to a silicate cement carbonization early strength agent with negative carbon function, and a preparation method and application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] With the introduction of the national dual carbon policy, the cement industry faces a formidable task of carbon reduction. Currently, there are three primary pathways for emissions reduction in the cement industry: source reduction, process reduction, and carbon capture technology. Source reduction is the most fundamental approach. Since the primary source of carbon is clinker, reducing the amount of clinker added during cement production can achieve this goal. However, cement's 28-day strength is directly related to the clinker content. According to empirical data from the cement industry, for every 1 MPa decrease in clinker strength, 1.5-2% more clinker must be added during cement production. Therefore, the most effective approach to source reduction is to maximize the 28-day strength of the clinker.

[0004] At present, the main measures to improve the 28-day strength of clinker are: (1) adjusting the clinker calcination conditions and mineral composition. However, this method will hinder the normal production process and has the disadvantage of high technical threshold, so cement manufacturers rarely adopt this method. (2) Adding early-strengthening admixtures. This method is currently widely used at home and abroad. However, most of the early-strengthening agents currently used on a large scale adopt organic synthesis, which is highly polluting and expensive. In addition, the early-strengthening principle of the early-strengthening agents circulating on the market is to accelerate the hydration of clinker minerals through the complexation of ions in the hydration process. However, this method has no effect on the strength of longer-term concrete structures, that is, it does not contribute to the later strength of concrete structures. Summary of the Invention

[0005] The present invention provides a carbonization accelerator for silicate cement with negative carbon functionality, as well as its preparation method and application. This agent not only effectively addresses the existing issues of high pollution, high cost, and poor long-term effectiveness, but also enables cement to absorb CO₂ from the air, providing a certain degree of carbon capture. Specifically, the present invention discloses the following technical solutions.

[0006] First, the present invention discloses a carbonization early strength agent for silicate cement with negative carbon function, comprising the following components: Ca2SiO4-α' L 0~8 parts by weight of powder, 0~5 parts by weight of Ca3Al2O6-o powder, and 0~5 parts by weight of CaO powder.L 、Ca3Al2O6-o were respectively + It is obtained by doping Ca2SiO4 and Ca3Al2O6, and its chemical formulas are K2O·23CaO·12SiO2 and K2O·8CaO·3Al2O3 respectively.

[0007] Furthermore, the Ca2SiO4-α' L The powder was prepared by the following method:

[0008] (1) Take the following raw materials: 6.13-6.34 parts by weight of CaO, 3.42-3.52 parts by weight of SiO2, and 0.23-0.4 parts by weight of K2O.

[0009] (2) After mixing the above raw materials, perform primary calcination, and then perform secondary calcination. The calcined product is rapidly cooled and ground into powder to obtain the Ca2SiO4-α' L powder.

[0010] Furthermore, in step (2), the temperature of the initial calcination is 1050-1100°C and the time is 1-2 hours. During this process, CaO begins to react with SiO2 to form Ca2SiO4, and the volume of the sample begins to change.

[0011] Furthermore, in step (2), the secondary calcination temperature is 1400-1450°C and the time is 5-6 hours. During this process, the reaction between CaO and SiO2 is accelerated, and K + Ions begin to dissolve into the Ca2SiO4 lattice, forming Ca2SiO4-α' L .

[0012] Furthermore, the Ca3Al2O6-o powder is prepared by the following method:

[0013] (i) Take the following raw materials: 5.29-5.32 parts by weight of CaO, 3.48-3.73 parts by weight of Al2O3, and 0.95-1.21 parts by weight of K2O.

[0014] (ii) The raw materials are mixed and then subjected to primary calcination, followed by secondary calcination. The calcined product is rapidly cooled and then ground into powder to obtain the Ca3Al2O6-o powder.

[0015] Furthermore, in step (ii), the temperature of the initial calcination is 850-950°C and the time is 2-4 hours. During this process, CaO and Al2O3 form CaAl2O4, a precursor product of the final product.

[0016] Furthermore, in step (ii), the secondary calcination temperature is 1250-1300°C and the time is 4-6 hours. During this process, the precursor product CaAl2O3 continues to react with CaO to form Ca3Al2O6, and at the same time a small amount of high temperature liquid phase is formed to make K + The ions quickly enter the Ca3Al2O6 lattice to form Ca3Al2O6-o.

[0017] Secondly, the present invention discloses a method for preparing the silicate cement carbonization early strength agent with negative carbon function, comprising the following steps: L The powder, Ca3Al2O6-o powder, CaO powder and anhydrous solvent are uniformly mixed to form a slurry, and the early strength agent is obtained after drying.

[0018] Furthermore, the mass ratio of the total mass of each of the powders to the anhydrous solvent is 1:0.5 to 1:1.5; optionally, the anhydrous solvent includes at least one of anhydrous ethanol, isopropanol, anhydrous methanol, glycerol, etc.

[0019] Furthermore, the drying temperature is 80-90° C., and the drying time is 1-2 hours.

[0020] Finally, the present invention discloses the use of the carbonization accelerator for silicate cement with negative carbon function in silicate cement. Optionally, the mass fraction of the accelerator in silicate cement is 2-7%.

[0021] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0022] First, the present invention provides a new type of silicate cement carbonization early strength agent. Compared with the preparation of organic synthetic early strength agents, the preparation process of the early strength agent of the present invention is pollution-free and the raw materials are very easy to obtain, which effectively reduces the preparation cost of the early strength agent.

[0023] Secondly, the Ca3Al2O6-o in the early strength agent of the present invention has the chemical property of significantly promoting water dissociation, so that when it encounters the mixing water in the silicate cement, it can promote the Ca3Al2O6-o to dissociate through the metal-proton exchange reaction. 2+ ions and K + The desorption of ions effectively increases the alkalinity of the hydration solution in silicate cement 3 days ago, allowing the cement to absorb a large amount of CO2 from the air at the initial stage of hydration. These carbon dioxide react with calcium hydroxide, the hydration product of silicate cement, to form calcium carbonate, which not only fills the pores of the cement paste but also generates a stronger hydration product, thereby improving the strength of the cement. The Ca2SiO4-α' L The hydration of α requires a long time to undergo metal-proton exchange reaction, so it releases K +The speed is relatively slow, thus replacing the Ca3Al2O6-o to improve the alkalinity of the hydration solution in the silicate cement after 3 days, achieving the effect of long-term carbon fixation, and not only has a very considerable negative carbon function. The CaO in the early strength agent forms a large number of calcium hydroxide crystal nuclei at the beginning of hydration, accelerating the hydration of silicate cement, and then forming more hydration products calcium hydroxide. At the same time, the absorbed CO2 further carbonizes the calcium hydroxide into calcium carbonate, which also plays a role in improving the strength of cement. The present invention uses Ca3Al2O6-o and Ca2SiO4-α' L The mutual synergy between them and the utilization of calcium hydroxide, the hydration product of silicate cement, and carbon dioxide in the air achieve the effect of improving the full-age strength of silicate cement. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0025] Figure 1 The Ca2SiO4-α' prepared in Example 1 below L XRD pattern of powder.

[0026] Figure 2 The XRD pattern of the Ca3Al2O6-o powder prepared in the following Example 1.

[0027] Figure 3 The following is an SEM image of cement hydrated for 28 days containing the early strength agent prepared in Example 1.

[0028] Figure 4 This is a SEM image of cement hydrated for 28 days containing the early strength agent prepared in Example 2 below.

[0029] Figure 5 This is a SEM image of cement hydrated for 28 days containing the early strength agent prepared in Example 3 below.

[0030] Figure 6 The following is an SEM image of cement hydrated for 28 days containing the early strength agent prepared in Example 4.

[0031] Figure 7 The following is an SEM image of cement hydrated for 28 days containing the early strength agent prepared in Example 5. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the invention. The experimental methods in the following examples, for which specific conditions are not specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0033] Unless otherwise defined, all professional and scientific terms used in the present invention have the same meanings as those familiar to those skilled in the art. The reagents and raw materials used in the present invention can be purchased through conventional channels. Unless otherwise specified, the reagents and raw materials used in the present invention are used in accordance with conventional methods in the art or in accordance with the product instructions.

[0034] In addition, any methods and materials similar or equivalent to those described herein can be applied to the method of the present invention. The technical solution of the present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0035] Comparative Example 1

[0036] To demonstrate the effects of admixtures throughout the curing period, this comparative example used the same 42.5% cement as in the following examples and prepared test specimens. Compressive strength tests were conducted at 3 and 28 days of curing according to "Test Methods for Cement Mortar Strength (ISO Method)" (GB / T 17671-1999). The results are shown below.

[0037]

[0038] Example 1

[0039] A method for preparing a silicate cement carbonization early strength agent with negative carbon function comprises the following steps:

[0040] 1. Ca2SiO4-α' L Powder preparation:

[0041] (1) The raw materials are as follows, by mass: 6.13 parts of CaO, 3.49 parts of SiO2, and 0.38 parts of K2O.

[0042] (2) The above raw materials were mixed with anhydrous ethanol in a mass ratio of 1:1 and magnetically stirred for 4 hours (rotation speed 300 rpm). The obtained slurry was then dried at 90°C for 10 hours. After completion, the dried product was loaded into a mold and pressed (pressure of 100 kN, the holding time of the pressure was 15 seconds) into a cylindrical raw material cake with a diameter of 50 mm and a thickness of 8 mm.

[0043] (3) The raw material cake is first heated to 1080°C at a temperature of 10°C / min and calcined for 1.5 hours, and then continued to be heated to 1420°C and calcined for 6 hours. After completion, the calcined product is quenched by blowing air, then ground and passed through an 80um square hole sieve to obtain the Ca2SiO4-α' L The powder has an X-ray diffraction pattern as shown Figure 2 shown.

[0044] 2. Preparation of Ca3Al2O6-o powder:

[0045] (1) The raw materials are as follows, by mass: 5.29 parts of CaO, 3.52 parts of Al2O3, and 1.19 parts of K2O.

[0046] (2) The above raw materials were mixed with isopropyl alcohol in a mass ratio of 1:0.5 and then magnetically stirred for 4 hours (rotation speed 300 rpm). The obtained slurry was then dried at 90°C for 10 hours. After completion, the dried product was loaded into a mold and pressed (pressure of 100 kN, the holding time of the pressure was 15 seconds) into a cylindrical raw cake with a diameter of 50 mm and a thickness of 8 mm.

[0047] (3) The raw cake is first heated to 900°C at a temperature of 10°C / min and calcined for 3 hours, and then further heated to 1300°C and calcined for 4 hours. After completion, the calcined product is quenched by blowing air, then ground and passed through an 80 μm square hole sieve to obtain the Ca3Al2O6-o powder, whose X-ray diffraction pattern is as follows: Figure 1 shown.

[0048] 3. Take the Ca2SiO4-α' prepared in this example L 5 parts by weight of powder, 3 parts by weight of Ca3Al2O6-O powder, and 2 parts by weight of CaO powder. Mix these powders with anhydrous ethanol in a 1:1 mass ratio and magnetically stir for 5 hours (300 rpm). Afterwards, dry the resulting slurry at 90°C for 1 hour to obtain the early strength agent.

[0049] Take 2 parts by weight of the early strength agent prepared in this example and 98 parts by weight of 42.5 ordinary Portland cement, mix the two and stir them evenly, then make test pieces of the obtained cement, and test the compressive strength of the test pieces after curing for 3 days and 28 days according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-1999). The results are shown in the table below. In addition, the microstructure of the test piece at the age of 28 days was observed under a scanning electron microscope. The results are as follows: Figure 3 As shown in the figure, the hydration products are mainly composed of coral-like CHS gel and cubic CaCO3, which are interlocked with each other, effectively filling the pores in the cement paste and improving the mechanical strength.

[0050]

[0051] Example 2

[0052] A method for preparing a silicate cement carbonization early strength agent with negative carbon function comprises the following steps:

[0053] 1. Ca2SiO4-α' L Powder preparation:

[0054] (1) The raw materials are as follows, calculated by mass: 6.34 parts of CaO, 3.43 parts of SiO2, and 0.23 parts of K2O.

[0055] (2) The above raw materials were mixed with anhydrous ethanol in a mass ratio of 1:1 and magnetically stirred for 4 hours (rotation speed 300 rpm). The obtained slurry was then dried at 90°C for 10 hours. After completion, the dried product was loaded into a mold and pressed (pressure of 100 kN, the holding time of the pressure was 15 seconds) into a cylindrical raw material cake with a diameter of 50 mm and a thickness of 8 mm.

[0056] (3) The raw material cake is first heated to 1100°C at a temperature of 10°C / min and calcined for 1 hour, and then further heated to 1450°C and calcined for 5 hours. After completion, the calcined product is rapidly cooled by blowing air, then ground and passed through an 80 μm square hole sieve to obtain the Ca2SiO4-α' L powder.

[0057] 2. Preparation of Ca3Al2O6-o powder:

[0058] (1) The raw materials are as follows: 5.3 parts of CaO, 3.6 parts of Al2O3, and 1.1 parts of K2O.

[0059] (2) The above raw materials were mixed with anhydrous ethanol in a mass ratio of 1:1 and magnetically stirred for 4 hours (rotation speed 300 rpm). The obtained slurry was then dried at 90°C for 10 hours. After completion, the dried product was loaded into a mold and pressed (pressure of 100 kN, the holding time of the pressure was 15 seconds) into a cylindrical raw material cake with a diameter of 50 mm and a thickness of 8 mm.

[0060] (3) The raw cake was first heated to 920°C at a temperature of 10°C / min and calcined for 3.5 hours, and then continued to be heated to 1280°C and calcined for 5 hours. After completion, the calcined product was quenched by blowing air, then ground and passed through an 80 μm square mesh sieve to obtain the Ca3Al2O6-o powder.

[0061] 3. Take the Ca2SiO4-α' prepared in this example L 4 parts by weight of powder, 3 parts by weight of Ca3Al2O6-O powder, and 3 parts by weight of CaO powder. Mix these powders with anhydrous ethanol in a 1:1 mass ratio and magnetically stir for 5 hours (300 rpm). Afterwards, dry the resulting slurry at 90°C for 1 hour to obtain the early strength agent.

[0062] Take 2 parts by weight of the early strength agent prepared in this example and 98 parts by weight of 42.5 ordinary Portland cement, mix the two and stir them evenly, then make test pieces of the obtained cement, and test the compressive strength of the test pieces after curing for 3 days and 28 days according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-1999). The results are shown in the table below. In addition, the microstructure of the test piece at the age of 28 days was observed under a scanning electron microscope. The results are as follows: Figure 4 As shown in the figure, the hydration products are mainly composed of a large number of fine CaCO3 and needle-shaped ettringite. Both products can effectively fill the pores of cement paste and greatly improve the mechanical strength.

[0063]

[0064] Example 3

[0065] A method for preparing a silicate cement carbonization early strength agent with negative carbon function comprises the following steps:

[0066] 1. Ca2SiO4-α' L Powder preparation:

[0067] (1) The raw materials are as follows, calculated by mass: 6.18 parts of CaO, 3.42 parts of SiO2, and 0.4 parts of K2O.

[0068] (2) The above raw materials were mixed with anhydrous ethanol in a mass ratio of 1:1 and magnetically stirred for 4 hours (rotation speed 300 rpm). The obtained slurry was then dried at 80°C for 12 hours. After completion, the dried product was loaded into a mold and pressed (pressure of 100 kN, the holding time of the pressure was 15 seconds) into a cylindrical raw material cake with a diameter of 50 mm and a thickness of 8 mm.

[0069] (3) The raw material cake is first heated to 1050°C at a temperature of 10°C / min and calcined for 2 hours, and then further heated to 1400°C and calcined for 6 hours. After completion, the calcined product is quenched by blowing air, then ground and passed through an 80 μm square hole sieve to obtain the Ca2SiO4-α' L powder.

[0070] 2. Preparation of Ca3Al2O6-o powder:

[0071] (1) The raw materials are as follows, by mass: 5.31 parts of CaO, 3.48 parts of Al2O3, and 1.21 parts of K2O.

[0072] (2) The above raw materials were mixed with anhydrous ethanol in a mass ratio of 1:1 and magnetically stirred for 4 hours (rotation speed 300 rpm). The obtained slurry was then dried at 80°C for 12 hours. After completion, the dried product was loaded into a mold and pressed (pressure of 100 kN, the holding time of the pressure was 15 seconds) into a cylindrical raw material cake with a diameter of 50 mm and a thickness of 8 mm.

[0073] (3) The raw cake was first heated to 850°C at a temperature of 10°C / min and calcined for 4 hours, and then continued to be heated to 1250°C and calcined for 6 hours. After completion, the calcined product was quenched by blowing air, then ground and passed through an 80 μm square mesh sieve to obtain the Ca3Al2O6-o powder.

[0074] 3. Take the Ca2SiO4-α' prepared in this example L 5 parts by weight of powder, 4 parts by weight of Ca3Al2O6-O powder, and 1 part by weight of CaO powder. Mix these powders with anhydrous ethanol in a 1:1 mass ratio and magnetically stir for 5 hours (300 rpm). Afterwards, dry the resulting slurry at 90°C for 1 hour to obtain the early strength agent.

[0075] Take 2 parts by weight of the early strength agent prepared in this example and 98 parts by weight of 42.5 ordinary Portland cement, mix the two and stir them evenly, then make test pieces of the obtained cement, and test the compressive strength of the test pieces after curing for 3 days and 28 days according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-1999). The results are shown in the table below. In addition, the microstructure of the test piece at the age of 28 days was observed under a scanning electron microscope. The results are as follows: Figure 5 As shown in the figure, the hydration products are covered with tiny cubic CaCO3 and a small amount of CSH gel. The tiny calcium carbonate not only has excellent mechanical strength, but also can effectively reduce the porosity of cement paste and improve its strength.

[0076]

[0077] Example 4

[0078] A method for preparing a silicate cement carbonization early strength agent with negative carbon function comprises the following steps:

[0079] 1. Ca2SiO4-α' L Powder preparation:

[0080] (1) Raw materials by mass: 6.21 parts of CaO, 3.51 parts of SiO2, and 0.28 parts of K2O

[0081] (2) The above raw materials were mixed with anhydrous ethanol in a mass ratio of 1:1 and magnetically stirred for 4 hours (rotation speed 300 rpm). The obtained slurry was then dried at 90°C for 10 hours. After completion, the dried product was loaded into a mold and pressed (pressure of 100 kN, the holding time of the pressure was 15 seconds) into a cylindrical raw material cake with a diameter of 50 mm and a thickness of 8 mm.

[0082] (3) The raw material cake is first heated to 1080°C at a temperature of 10°C / min and calcined for 1.5 hours, and then continued to be heated to 1420°C and calcined for 6 hours. After completion, the calcined product is quenched by blowing air, then ground and passed through an 80um square hole sieve to obtain the Ca2SiO4-α' L powder.

[0083] 2. Preparation of Ca3Al2O6-o powder:

[0084] (1) The raw materials are as follows, by mass: 5.32 parts of CaO, 3.65 parts of Al2O3, and 1.03 parts of K2O.

[0085] (2) The above raw materials were mixed with anhydrous methanol in a mass ratio of 1:1.2 and magnetically stirred for 4 hours (rotation speed 300 rpm). The obtained slurry was then dried at 90°C for 10 hours. After completion, the dried product was loaded into a mold and pressed (pressure of 100 kN, the holding time of the pressure was 15 seconds) into a cylindrical raw material cake with a diameter of 50 mm and a thickness of 8 mm.

[0086] (3) The raw cake was first heated to 900°C at a temperature of 10°C / min and calcined for 3 hours, and then continued to be heated to 1300°C and calcined for 4 hours. After completion, the calcined product was quenched by blowing air, then ground and passed through an 80 μm square mesh sieve to obtain the Ca3Al2O6-o powder.

[0087] 3. Take the Ca2SiO4-α' prepared in this example L 7 parts by weight of powder, 1 part by weight of Ca3Al2O6-O powder, and 2 parts by weight of CaO powder. Mix these powders with anhydrous ethanol in a 1:1 mass ratio and magnetically stir for 5 hours (300 rpm). Afterwards, dry the resulting slurry at 80°C for 2 hours to obtain an early strength agent.

[0088] Take 5 parts by weight of the early strength agent prepared in this example and 95 parts by weight of 42.5 ordinary Portland cement, mix the two and stir them evenly, then make test pieces of the obtained cement, and test the compressive strength of the test pieces after curing for 3 days and 28 days according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-1999). The results are shown in the following table. In addition, the microstructure of the test piece at the age of 28 days was observed under a scanning electron microscope. The results are as follows: Figure 6 As shown in the figure, the hydration products are mainly composed of flaky CSH gel, cubic CaCO3 and a small amount of needle-shaped ettringite. These hydration products are bonded and interlocked with each other, effectively improving the mechanical strength.

[0089]

[0090] Example 5

[0091] A method for preparing a silicate cement carbonization early strength agent with negative carbon function comprises the following steps:

[0092] 1. Ca2SiO4-α' L Powder preparation:

[0093] (1) The raw materials are as follows, calculated by mass: 6.18 parts of CaO, 3.52 parts of SiO2, and 0.3 parts of K2O.

[0094] (2) The above raw materials were mixed with isopropyl alcohol in a mass ratio of 1:1 and magnetically stirred for 4 hours (rotation speed 300 rpm). The obtained slurry was then dried at 90°C for 10 hours. After completion, the dried product was loaded into a mold and pressed (pressure of 100 kN, the holding time of the pressure was 15 seconds) into a cylindrical raw material cake with a diameter of 50 mm and a thickness of 8 mm.

[0095] (3) The raw material cake is first heated to 1050°C at a temperature of 10°C / min and calcined for 2 hours, and then further heated to 1450°C and calcined for 5 hours. After completion, the calcined product is quenched by blowing air, then ground and passed through an 80 μm square hole sieve to obtain the Ca2SiO4-α' L powder.

[0096] 2. Preparation of Ca3Al2O6-o powder:

[0097] (1) The raw materials are as follows, by mass: 5.32 parts of CaO, 3.73 parts of Al2O3, and 0.95 parts of K2O.

[0098] (2) The above raw materials were mixed with isopropyl alcohol in a mass ratio of 1:1.5 and then magnetically stirred for 4 hours (rotation speed 300 rpm). The obtained slurry was then dried at 90°C for 10 hours. After completion, the dried product was loaded into a mold and pressed (pressure of 100 kN, the holding time of the pressure was 15 seconds) into a cylindrical raw cake with a diameter of 50 mm and a thickness of 8 mm.

[0099] (3) The raw cake was first heated to 950°C at a temperature of 10°C / min and calcined for 2 hours, and then continued to be heated to 1300°C and calcined for 4 hours. After completion, the calcined product was quenched by blowing air, then ground and passed through an 80 μm square mesh sieve to obtain the Ca3Al2O6-o powder.

[0100] 3. Take the Ca2SiO4-α' prepared in this example L 5 parts by weight of powder, 2 parts by weight of Ca3Al2O6-O powder, and 3 parts by weight of CaO powder. Mix these powders with isopropyl alcohol in a 1:1 mass ratio and magnetically stir for 5 hours (300 rpm). Dry the resulting slurry at 80°C for 2 hours to obtain the early strength agent.

[0101] Take 7 parts by weight of the early strength agent prepared in this example and 93 parts by weight of 42.5 ordinary Portland cement, mix the two and stir them evenly, then make test pieces of the obtained cement, and test the compressive strength of the test pieces after curing for 3 days and 28 days according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-1999). The results are shown in the following table. In addition, the microstructure of the test piece at the age of 28 days was observed under a scanning electron microscope. The results are as follows: Figure 7 As shown in the figure, the hydration products are mainly composed of flaky CSH gel and cubic CaCO3. These hydration products are bonded and interlocked with each other, effectively improving the mechanical strength.

[0102]

[0103] Example 6

[0104] A preparation method of a carbonization early strength agent for silicate cement with negative carbon function, which differs from the above embodiment 1 in that the early strength agent in this embodiment is composed of Ca2SiO4-α' L The powder is 8 parts by weight and the CaO powder is 2 parts by weight, that is, it does not contain Ca3Al2O6-o powder.

[0105] The same method as in Example 1 was used to test the 3d and 28d compressive strength of the cement specimens containing the early strength agent of this example. The results are shown in the following table.

[0106]

[0107] Example 7

[0108] A method for preparing a carbonization early strength agent for silicate cement with negative carbon function, which differs from the above embodiment 2 in that the early strength agent in this embodiment is composed of 5 parts by weight of Ca3Al2O6-o powder and 5 parts by weight of CaO powder, i.e., it does not contain Ca2SiO4-α' L powder.

[0109] The same method as in Example 2 was used to test the 3d and 28d compressive strength of the cement specimens containing the early strength agent of this example. The results are shown in the following table.

[0110]

[0111] Example 8

[0112] A preparation method of a carbonization early strength agent for silicate cement with negative carbon function, which is different from the above embodiment 3 in that the early strength agent in this embodiment is composed of Ca2SiO4-α' L The powder is 6 parts by weight and the Ca3Al2O6-o powder is 4 parts by weight, that is, it does not contain CaO powder.

[0113] The same method as in Example 3 was used to test the 3d and 28d compressive strength of the cement specimens containing the early strength agent of this example. The results are shown in the following table.

[0114]

[0115] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A carbonization early strength agent for silicate cement with negative carbon function, characterized in that: Includes the following components: Ca2SiO4-α' L 0~8 parts by weight of powder, 0~5 parts by weight of Ca3Al2O6-o powder, 0~5 parts by weight of CaO powder. Among the above three components, the weight of any two or more components cannot be 0 at the same time; wherein: the Ca2SiO4-α' L 、Ca3Al2O6-o were respectively + It is obtained by doping Ca2SiO4 and Ca3Al2O6, and its chemical formulas are K2O·23CaO·12SiO2 and K2O·8CaO·3Al2O3 respectively.

2. The carbonization early strength agent for silicate cement with negative carbon function according to claim 1, characterized in that: The Ca2SiO4-α' L The powder was prepared by the following method: (1) Take the following raw materials: 6.13-6.34 parts by weight of CaO, 3.42-3.52 parts by weight of SiO2, and 0.23-0.4 parts by weight of K2O; (2) After mixing the above raw materials, perform primary calcination, and then perform secondary calcination. The calcined product is rapidly cooled and ground into powder to obtain the Ca2SiO4-α' L powder.

3. The carbonization early strength agent for silicate cement with negative carbon function according to claim 2, characterized in that: In step (2), the temperature of the initial calcination is 1050-1100° C., and the time is 1-2 hours.

4. The carbonization early strength agent for silicate cement with negative carbon function according to claim 2, characterized in that: In step (2), the secondary calcination temperature is 1400-1450° C. and the time is 5-6 hours.

5. The carbonization early strength agent for silicate cement with negative carbon function according to claim 1, characterized in that: The Ca3Al2O6-o powder is prepared by the following method: (i) Prepare the following raw materials: 5.29-5.32 parts by weight of CaO, 3.48-3.73 parts by weight of Al2O3, and 0.95-1.21 parts by weight of K2O; (ii) The above raw materials are mixed and then calcined for the first time, and then calcined for the second time. The calcined product is rapidly cooled and ground into powder to obtain the Ca2SiO4-α' L powder.

6. The carbonization early strength agent for silicate cement with negative carbon function according to claim 5, characterized in that: In step (ii), the temperature of the primary calcination is 850-950° C., and the time is 2-4 hours.

7. The carbonization early strength agent for silicate cement with negative carbon function according to claim 5, characterized in that: In step (ii), the secondary calcination temperature is 1250-1300° C. and the time is 4-6 hours.

8. The method for preparing the carbonization early strength agent for silicate cement with negative carbon function according to any one of claims 1 to 7, characterized in that: The steps include: L The powder, Ca3Al2O6-o powder, CaO powder and anhydrous solvent are uniformly mixed to form a slurry, and the early strength agent is obtained after drying.

9. The method for preparing the carbonization early strength agent for silicate cement with negative carbon function according to claim 8, characterized in that: The mass ratio of the total mass of each of the powders to the anhydrous solvent is 1:0.5 to 1:1.

5.

10. The method for preparing the silicate cement carbonization early strength agent with negative carbon function according to claim 8, characterized in that: The anhydrous solvent includes at least one of anhydrous ethanol, isopropyl alcohol, anhydrous methanol, and glycerol.

11. The method for preparing the silicate cement carbonization early strength agent with negative carbon function according to claim 8, characterized in that: The drying temperature is 80-90° C., and the drying time is 1-2 hours.

12. Use of the carbonization early strength agent for silicate cement with negative carbon function according to any one of claims 1 to 7 or the early strength agent obtained by the preparation method according to any one of claims 8 to 11 in silicate cement.

13. The use according to claim 12, wherein the mass fraction of the early strength agent in the Portland cement is 2-7%.

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