A calcium aluminoferrite-calcium sulfosilicate cement-based expansion agent and its preparation method and application

Abstract

The present invention relates to the technical field of cement material preparation, and specifically discloses a calcium aluminoferrite-calcium sulfosilicate cement-based expansion agent and its preparation method and application. The expansion agent includes expansion source powder, gypsum powder and a regulating agent. The expansion source powder includes: calcium aluminoferrite 45~55wt.%, calcium sulfosilicate 30~40wt.%, calcium sulfoaluminate 5~10wt.%, dicalcium silicate 5~10wt.%, calcium sulfate 2~4 wt.%; the remainder is an inevitable impurity mineral phase; the calcium aluminoferrite includes dicalcium ferrite, hexacalcium dialuminate, tetracalcium aluminoferrite, and hexacalcium dialuminate. The gypsum powder is 12~18% of the mass of the expansion source powder; the regulating agent is triethanolamine or propanolamine, which is 0.1~0.5% of the total mass of the expansion source powder and gypsum powder. The expansion agent of the present invention can provide continuous and coherent expansion for the entire hydration and hardening stage of cement-based cementitious materials without interference with the fluidity of concrete, and the expansion performance is stable for a long time.

Description

Technical Field

[0001] The invention relates to the technical field of cement material preparation, and in particular to a calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent and a preparation method and application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the 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 a person skilled in the art.

[0003] Concrete shrinkage cracking accelerates the invasion of corrosive media, seriously endangering the durability and service life of building structures, and is a major technical problem plaguing the field of civil engineering. Expansive agents react with water to form expansive substances, which can compensate for the shrinkage cracking of concrete during the hardening stage and are an important measure to inhibit the generation of cracks in concrete structures.

[0004] At present, the commonly used expansion agents in concrete mainly include: calcium sulfoaluminate, calcium oxide, magnesium oxide, etc. Among them, after the gypsum in the calcium sulfoaluminate expansion agent system is consumed, the SO4 2- The concentration decreases, causing calcium sulfoaluminate to be converted into monosulfur hydrated calcium sulfoaluminate. In addition, high temperatures inside large-volume concrete will also promote the above conversion, resulting in reduced expansion performance. The calcium oxide expansion agent has a high expansion rate, but the hydration rate is too fast. The hydration degree can reach 50% in 2 hours under normal temperature conditions, resulting in reduced expansion performance during the concrete hardening stage, and the expansion is mainly concentrated before 3 days, resulting in unstable expansion performance, high in the early stage, and low in the middle and late stages. Calcium oxide-calcium sulfoaluminate composite expansion agent will reduce the fluidity of concrete. The magnesite required for the preparation of magnesium oxide is mainly distributed in the Liaodong Peninsula and Jiaodong Peninsula in my country, and is a strategic resource, which largely limits the widespread application of the expansion agent. Summary of the invention

[0005] The present invention provides a calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent and a preparation method and application thereof, which has no interference with the fluidity of concrete, can provide continuous and coherent expansion for the entire hydration and hardening stage of cement-based cementitious materials, and has the advantage of long-term stable expansion performance. Specifically, the technical solution of the present invention is as follows.

[0006] First, the present invention provides a calcium aluminoferrite-calcium sulfosilicate cement-based expansion agent, comprising an expansion source powder, gypsum powder and a regulator. The expansion source powder comprises: calcium aluminoferrite (Ca2Al x F 2-xO5) 45~55wt.%, calcium sulfosilicate (C5S2$) 30~40wt.%, calcium sulfoaluminate (C4A3$) 5~10 wt.%, dicalcium silicate (C2S) 5~10 wt.%, calcium sulfate (CaSO4) 2~4wt.%, and the remainder is an inevitable impurity mineral phase. The calcium aluminoferrite includes at least two of dicalcium ferrite (C2F), hexacalcium aluminoferrate (C6AF2), tetracalcium aluminoferrate (C4AF), and hexacalcium aluminoferrate (C6A2F). The gypsum powder is 12~18% of the mass of the expansion source powder. The regulating agent is triethanolamine or propanolamine, which is 0.1~0.5% of the total mass of the expansion source powder and the gypsum powder.

[0007] Furthermore, the calcium thiosilicate contains a solid solution of sodium element, and the content of sodium element is 0.1-0.6% of the mass of the calcium thiosilicate.

[0008] Secondly, the present invention provides a method for preparing a calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent, comprising the following steps:

[0009] (1) The calcium oxide source, red mud, silicon source, aluminum source and calcium sulfate source are mixed evenly and then calcined. After the calcination is completed, the calcined product is sequentially quenched and crushed to obtain the expansion source powder.

[0010] (2) The expansion source powder and gypsum powder are mixed evenly to obtain component A, which is set aside.

[0011] (3) The component A is mixed evenly with the regulating agent to obtain the cement expansion agent.

[0012] Furthermore, in step (1), the weight ratio of each raw material is: 81.73-84.86 parts of calcium oxide source, 22.44-32.74 parts of red mud, 12.77-19.11 parts of silicon source, 6.15-11.32 parts of aluminum source, and 8.61-12.13 parts of calcium sulfate source.

[0013] Furthermore, in step (1), 0.95 to 1.45 parts by weight of a sodium source is also included. Optionally, the sodium source includes at least one of sodium oxide, sodium carbonate, sodium hydroxide, etc. Trace element Na can significantly increase the hydration activity of the calcium sulfosilicate mineral, prompting it to produce a large amount of dihydrate gypsum in the early and middle hydration stages, which can further react with the active aluminum component in silicate cement to form calcium sulfonate, and produce micro-expansion in the late stage of cement hydration.

[0014] Furthermore, in step (1), the calcium oxide source includes at least one of limestone, carbide slag, quicklime, calcium hydroxide, etc. After high-temperature calcination, the calcium oxide source can form the effective ingredient required by the present invention, providing the required components for the formation of calcium aluminoferrite and calcium sulfosilicate.

[0015] Furthermore, in step (1), the red mud includes at least one of Bayer process red mud, sintering process red mud, combined process red mud, etc.

[0016] Furthermore, in step (1), the silicon source includes at least one of sandstone, fly ash, etc. In the present invention, the silicon source is mainly used to form the calcium sulfosilicate and dicalcium silicate, providing good expansion properties.

[0017] Furthermore, in step (1), the aluminum source includes at least one of aluminum ash, bauxite, etc. In the present invention, the main function of the aluminum source is to provide Al2O3 for the formation of active aluminum-containing minerals such as calcium ferroaluminate, thereby stimulating the hydration activity of the calcium sulfosilicate mineral phase to form ettringite.

[0018] Furthermore, in step (1), the calcium sulfate source includes at least one of phosphogypsum, fluorgypsum, titanium gypsum, desulfurized gypsum, and pure calcium sulfate reagent.

[0019] Furthermore, in step (1), the calcination temperature is 1100-1200° C., and the calcination time is 5-20 min.

[0020] Furthermore, in step (1), the rapid cooling method includes any one of wind cooling, air cooling, liquid nitrogen cooling, etc.

[0021] Finally, the present invention provides the use of the calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent in a silicate cement-based cementitious material. Optionally, the expansion agent is added in an amount of 5-15% of the mass of the silicate cement-based cementitious material.

[0022] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0023] (1) When the cement-based expansive agent of the present invention is added to the cement-based cementitious material, the calcium aluminoferrate, calcium sulfoaluminate and calcium sulfate react with each other to form expansive ettringite, which provides expansion for the early hydration stage of the cement-based cementitious material. Then the calcium sulfosilicate with lower hydration activity begins to play a role, and the calcium sulfate formed by its hydration continues to react with the remaining calcium aluminoferrate to form expansive ettringite (AFt), which provides micro-expansion for the middle and late hydration stages of the cement-based cementitious material, so that the expansive agent of the present invention provides continuous and coherent expansion throughout the cement hydration and hardening stage, and compacts and fills the pores generated in the cement hydration and hardening stage. At the same time, in this process, the triethanolamine acts as a regulator to coordinate the hydration of calcium aluminoferrate. This is because the hydration activity of calcium aluminoferrate (hexacalcium dialuminoferrate, tetracalcium dialuminoferrate, hexacalcium dialuminoferrate) with different iron-aluminum ratios is inconsistent. Among them, the hydration activity of hexacalcium dialuminoferrate is relatively high, and it can be hydrated in the early stage of cement hydration, while the hydration activity of dicalcium ferrite, hexacalcium dialuminoferrate, etc. is very low, and it is difficult to relay after the hydration of the hexacalcium dialuminoferrate is completed. The triethanolamine can accelerate the calcium aluminoferrate with low hydration activity, so that the calcium aluminoferrate with different iron-aluminum ratios can relay each other, thereby providing continuous micro-expansion throughout the entire stage of cement hydration and hardening. The CSH gel generated by the hydration of dicalcium silicate and the above-mentioned calcium sulfonate also help to improve the strength of cement-based materials. The propanolamine can accelerate the dissolution of gypsum. As the curing age increases, more sulfate will be consumed to form AFt. At the same time, propanolamine will promote the hydration of aluminum-containing phase minerals and react with sulfate to generate AFt faster.

[0024] (2) After calcium sulfosilicate has reacted with the remaining calcium aluminoferrate, the remaining calcium sulfosilicate continues to hydrate, releasing SO4 2- The concentration can increase the SO4 2- The concentration of SO4 in the hydrated liquid phase effectively inhibits the transformation of the slightly expanded ettringite into the monosulfur type calcium sulfoaluminate hydrate which does not have the expansion property. 2- The increase in concentration can also inhibit the high-temperature decomposition of ettringite. Therefore, the expansion provided by the expansion agent of the present invention also has good long-term stability.

[0025] (3) The expansion agent of the present invention does not interfere with the fluidity of cement-based cementitious materials, thus avoiding the problem of reduced fluidity and increased difficulty in pumping and transportation. In addition, the concrete calcium aluminoferrite-calcium sulfosilicate expansion agent of the present invention uses industrial solid waste as a source material, which is conducive to the safe management and recycling of industrial solid waste, reduces environmental pollution and resource waste, and reduces costs, thereby having significant environmental and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings in the specification, 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.

[0027] Figure 1 This is a picture of the expansion source powder sample prepared in the following Example 1.

[0028] Figure 2 This is the XRD test diagram of the expansion source powder prepared in the following Example 1.

[0029] Figure 3 This is a test chart of the limited expansion rate of the calcium aluminate-calcium sulfosilicate cement-based expansive agent prepared in the following Example 1.

[0030] Figure 4 The compressive strength test diagram of the specimen containing the expansion agent prepared in the following Example 1.

[0031] Figure 5 This is a picture of the expansion source powder sample prepared in the following Example 2.

[0032] Figure 6 This is a picture of the expansion source powder sample prepared in the following Example 3.

[0033] Figure 7 This is a picture of the expansion source powder sample prepared in the following Example 4.

[0034] Figure 8 This is a picture of the expansion source powder sample prepared in the following Example 5.

[0035] Fig. 9 This is the XRD test pattern of the expansion source powder prepared in the following Example 5.

[0036] Fig.10 This is a picture of the expansion source powder sample prepared in the following Example 6.

[0037] Fig.11 This is the XRD test pattern of the expansion source powder prepared in the following Example 6.

[0038] Fig.12 This is a picture of the expansion source powder sample prepared in the following Example 7. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0040] 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 or raw materials used in the present invention can be purchased through conventional channels. Unless otherwise specified, the reagents or raw materials used in the present invention are used in a conventional manner in the art or in accordance with the product instructions.

[0041] In addition, any method and material similar or equivalent to the described content can be applied to the method of the present invention. The technical solution of the present invention is further described in conjunction with the accompanying drawings and specific embodiments.

[0042] Example 1

[0043] A method for preparing a calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent comprises the following steps:

[0044] (1) Take the following raw materials in the following weight ratios: 84.31 parts of calcium oxide source (limestone), 26.29 parts of Bayer red mud, 19.11 parts of silicon source (fly ash), 11.32 parts of aluminum source (aluminum ash), 10.18 parts of calcium sulfate source (fluorgypsum), and 1.45 parts of sodium source (sodium carbonate).

[0045] (2) The calcium oxide source, red mud, silicon source, aluminum source, calcium sulfate source and sodium source are mixed uniformly. The raw material is then heated to 1100°C at a heating rate of 10°C / min and calcined for 15 minutes. After completion, the calcined product is first air-cooled to room temperature and then ground to obtain an expansion source powder, such as Figure 1 shown.

[0046] (3) Take gypsum powder with a mass ratio of 12% of the expansion source powder, mix the two evenly, and obtain component A for later use.

[0047] (4) Take 0.3% by weight of triethanolamine of component A and mix the two components evenly to obtain a cement expansion agent.

[0048] Figure 2 The XRD test diagram of the expansion source powder prepared in this embodiment shows that the main components of the expansion source powder include calcium aluminoferrite (Ca2Al x F 2-x O5), calcium sulfosilicate (C5S2$), calcium sulfoaluminate (C4A3$), dicalcium silicate (C2S) and calcium sulfate (CaSO4). The calculated content of calcium aluminoferrite is 45.04wt.%, the content of calcium sulfosilicate is 31.51wt.%, the content of calcium sulfoaluminate is 9.97wt.%, the content of dicalcium silicate is 10.02wt.%, the content of calcium sulfate is 2.61wt.%, and the rest is the inevitable impurity mineral phase. Among them, calcium aluminoferrite (Ca2Al x F 2-xO5) includes dicalcium ferrite (C2F), hexacalcium dialuminoferrite (C6AF2), tetracalcium aluminoferrite (C4AF), and hexacalcium dialuminoferrite (C6A2F). The calcium sulfosilicate contains 0.608% sodium by weight in solid solution.

[0049] Performance test: The limited expansion rate of the cement expansion agent prepared in this embodiment in air (such as Figure 3 As shown) and the 28d compressive strength of the cement mortar specimens added with the expansion agent (as shown Figure 4 As shown), the results are: limited expansion rate = -0.009%, 28d compressive strength = 56MPa. In addition, a comparative example without the addition of triethanolamine was set, and the limited expansion rate = -0.011%, 28d compressive strength = 51.24Mpa were measured.

[0050] Example 2

[0051] A method for preparing a calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent comprises the following steps:

[0052] (1) Take the following raw materials in the following weight ratios: 84.86 parts of calcium oxide source (carbide slag), 32.74 parts of Bayer red mud, 12.77 parts of silicon source (fly ash), 8.14 parts of aluminum source (aluminum ash), 8.61 parts of calcium sulfate source (desulfurized gypsum), and 0.95 parts of sodium source (sodium oxide).

[0053] (2) The calcium oxide source, red mud, silicon source, aluminum source, calcium sulfate source and sodium source are mixed uniformly. The raw material is then heated to 1200°C at a heating rate of 10°C / min and calcined for 5 minutes. After completion, the calcined product is first air-cooled to room temperature and then ground to obtain an expansion source powder, such as Figure 5 shown.

[0054] (3) Take gypsum powder with a mass ratio of 15% of the expansion source powder, mix the two evenly, and obtain component A for later use.

[0055] (4) Take 0.5% by weight of propanolamine of component A and mix the two components evenly to obtain a cement expansion agent.

[0056] The main components of the expansion source powder prepared in this embodiment are measured to include: calcium aluminoferrite (Ca2Al x F 2-xO5), calcium sulfosilicate (C5S2$), calcium sulfoaluminate (C4A3$), dicalcium silicate (C2S) and calcium sulfate (CaSO4). The calculated content of calcium aluminoferrite is 54.98wt.%, the content of calcium sulfosilicate is 30.01wt.%, the content of calcium sulfoaluminate is 5.05wt.%, the content of dicalcium silicate is 6.39wt.%, the content of calcium sulfate is 1.98wt.%, and the remainder is the inevitable impurity mineral phase. Among them, calcium aluminoferrite (Ca2Al x F 2-x O5) includes dicalcium ferrite (C2F), hexacalcium dialuminoferrite (C6AF2), tetracalcium aluminoferrite (C4AF), and hexacalcium dialuminoferrite (C6A2F). The calcium sulfosilicate contains 0.102% sodium by mass in solid solution.

[0057] Performance test: The limited expansion rate of the cement expansive agent prepared in this embodiment in air and the 28d compressive strength of the cement mortar specimen added with the expansive agent were tested with reference to the national standard GB / T 23439-2017 "Concrete Expansive Agent". The results are: limited expansion rate = -0.008%, 28d compressive strength = 59MPa. In addition, a comparative example without the addition of the propanolamine was set, and the limited expansion rate = -0.010%, 28d compressive strength = 55.36Mpa were measured.

[0058] Example 3

[0059] A method for preparing a calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent comprises the following steps:

[0060] (1) Take the following raw materials in the following weight ratios: 81.73 parts of calcium oxide source (calcium hydroxide), 24.22 parts of sintered red mud, 14.41 parts of silicon source (sandstone), 6.15 parts of aluminum source (alumina), 12.13 parts of calcium sulfate source (phosphogypsum), and 1.13 parts of sodium source (sodium hydroxide).

[0061] (2) The calcium oxide source, red mud, silicon source, aluminum source, calcium sulfate source and sodium source are mixed uniformly. The raw material is then heated to 1130°C at a heating rate of 10°C / min and calcined for 20 minutes. After completion, the calcined product is first air-cooled to room temperature and then ground to obtain an expansion source powder, such as Figure 6 shown.

[0062] (3) Take gypsum powder with a mass ratio of 18% of the expansion source powder, mix the two evenly, and obtain component A for later use.

[0063] (4) Take 0.1% propanolamine by weight of the A component and mix the two components evenly to obtain a cement expansion agent.

[0064] The main components of the expansion source powder prepared in this embodiment are measured to include: calcium aluminoferrite (Ca2Al x F 2-x O5), calcium sulfosilicate (C5S2$), calcium sulfoaluminate (C4A3$), dicalcium silicate (C2S) and calcium sulfate (CaSO4). The calculated content of calcium aluminoferrite is 42.26wt.%, the content of calcium sulfosilicate is 40.03wt.%, the content of calcium sulfoaluminate is 7.14wt.%, the content of dicalcium silicate is 4.99wt.%, the content of calcium sulfate is 4.06wt.%, and the remainder is the inevitable impurity mineral phase. Among them, calcium aluminoferrite (Ca2Al x F 2-x O5) includes dicalcium ferrite (C2F), hexacalcium dialuminoferrite (C6AF2), tetracalcium aluminoferrite (C4AF), and hexacalcium dialuminoferrite (C6A2F). The calcium sulfosilicate contains 0.37% sodium by weight in solid solution.

[0065] Performance test: The limited expansion rate of the cement expansive agent prepared in this embodiment in air and the 28d compressive strength of the cement mortar specimen added with the expansive agent were tested with reference to the national standard GB / T 23439-2017 "Concrete Expansive Agent". The results are: limited expansion rate = -0.012%, 28d compressive strength = 53MPa. In addition, a comparative example without the addition of the propanolamine was set, and the limited expansion rate = -0.014%, 28d compressive strength = 49.25Mpa were measured.

[0066] Example 4

[0067] A method for preparing a calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent comprises the following steps:

[0068] (1) Take the following raw materials in the following weight ratios: 84.86 parts of calcium oxide source (carbide slag), 32.74 parts of Bayer red mud, 12.77 parts of silicon source (fly ash), 8.14 parts of aluminum source (aluminum ash), and 8.61 parts of calcium sulfate source (desulfurized gypsum).

[0069] (2) The calcium oxide source, red mud, silicon source, aluminum source and calcium sulfate source are mixed evenly. The raw material is then heated to 1200°C at a heating rate of 10°C / min and calcined for 5 minutes. After completion, the calcined product is first air-cooled to room temperature and then ground to obtain an expansion source powder, such as Figure 7 shown.

[0070] (3) Take gypsum powder with a mass ratio of 15% of the expansion source powder, mix the two evenly, and obtain component A for later use.

[0071] (4) Take 0.5% by weight of propanolamine of component A and mix the two components evenly to obtain a cement expansion agent.

[0072] The main components of the expansion source powder prepared in this embodiment are measured to include: calcium aluminoferrite (Ca2Al x F 2-x O5), calcium sulfosilicate (C5S2$), calcium sulfoaluminate (C4A3$), dicalcium silicate (C2S) and calcium sulfate (CaSO4). The calculated content of calcium aluminoferrite is 54.32wt.%, the content of calcium sulfosilicate is 28.76wt.%, the content of calcium sulfoaluminate is 6.13wt.%, the content of dicalcium silicate is 7.42wt.%, the content of calcium sulfate is 2.43wt.%, and the remainder is the inevitable impurity mineral phase. Among them, calcium aluminoferrite (Ca2Al x F 2-x O5) includes dicalcium ferrite (C2F), hexacalcium aluminoferrite (C6AF2), tetracalcium aluminoferrite (C4AF), and hexacalcium ferrite dicalcium (C6A2F).

[0073] Performance test: Referring to the national standard GB / T 23439-2017 "Concrete Expansion Agent", the limited expansion rate of the cement expansive agent prepared in this embodiment in the air and the 28d compressive strength of the cement mortar specimen added with the expansive agent were tested. The results were: limited expansion rate = -0.016%, 28d compressive strength = 47.04MPa.

[0074] Example 5

[0075] A method for preparing a calcium aluminoferrite cement-based expansion agent comprises the following steps:

[0076] (1) Take the following raw materials in the following weight ratios: 85.42 parts of calcium oxide source (limestone), 47.93 parts of Bayer red mud, 12.17 parts of silicon source (fly ash), 7.32 parts of aluminum source (aluminum ash), 3.01 parts of calcium sulfate source (fluorgypsum), and 1.45 parts of sodium source (sodium carbonate).

[0077] (2) The calcium oxide source, red mud, silicon source, aluminum source, calcium sulfate source and sodium source are mixed uniformly. The raw material is then heated to 1100°C at a heating rate of 10°C / min and calcined for 15 minutes. After completion, the calcined product is first air-cooled to room temperature and then ground to obtain an expansion source powder.

[0078] (3) Take gypsum powder with a mass ratio of 12% of the expansion source powder, mix the two evenly, and obtain component A for later use.

[0079] (4) Take 0.3% by weight of triethanolamine of component A and mix the two components evenly to obtain a cement expansion agent.

[0080] Fig. 9The XRD test diagram of the expansion source powder prepared in this embodiment shows that the main components of the expansion source powder include: calcium aluminoferrite (Ca2Al x F 2-x O5), calcium sulfoaluminate (C4A3$), dicalcium silicate (C2S) and calcium sulfate (CaSO4). The calculated content of calcium aluminoferrite is 53.45wt.%, the content of calcium sulfoaluminate is 19.97wt.%, the content of dicalcium silicate is 18.17wt.%, the content of calcium sulfate is 4.21wt.%, and the rest is the inevitable impurity mineral phase. x F 2-x O5) includes dicalcium ferrite (C2F), hexacalcium aluminoferrite (C6AF2), tetracalcium aluminoferrite (C4AF), and hexacalcium ferrite dicalcium (C6A2F).

[0081] Performance test: Referring to the national standard GB / T 23439-2017 "Concrete Expansion Agent", the limited expansion rate of the cement expansive agent prepared in this embodiment in the air and the 28d compressive strength of the cement mortar specimen added with the expansive agent were tested. The results were: limited expansion rate = -0.023%, 28d compressive strength = 44.51 MPa.

[0082] Example 6

[0083] A method for preparing a calcium sulfosilicate cement-based expansion agent comprises the following steps:

[0084] (1) Take the following raw materials in the following weight ratios: 90.92 parts of calcium oxide source (limestone), 15.59 parts of silicon source (sandstone), 19.29 parts of aluminum source (fly ash), 18.07 parts of calcium sulfate source (fluorgypsum), and 1.13 parts of sodium source (sodium hydroxide).

[0085] (2) The calcium oxide source, silicon source, aluminum source, calcium sulfate source and sodium source are mixed evenly. The raw material is then heated to 1130°C at a heating rate of 10°C / min and calcined for 15 minutes. After completion, the calcined product is first air-cooled to room temperature and then ground to obtain an expansion source powder, such as Fig.10 shown.

[0086] (3) Take gypsum powder with a mass ratio of 15% of the expansion source powder, mix the two evenly, and obtain component A for later use.

[0087] (4) Take 0.5% by weight of triethanolamine of component A and mix the two components evenly to obtain a cement expansion agent.

[0088] Fig.11From the XRD test diagram of the expansion source powder prepared in this embodiment, it can be seen that the main components of the expansion source powder include: calcium sulfosilicate (C5S2$), calcium sulfoaluminate (C4A3$), dicalcium silicate (C2S) and calcium sulfate (CaSO4). The calculated content of calcium sulfosilicate is 47.32wt.%, the content of calcium sulfoaluminate is 17.45wt.%, the content of dicalcium silicate is 30.26wt.%, the content of calcium sulfate is 1.93wt.%, and the balance is the inevitable impurity mineral phase. The calcium sulfosilicate has a solid solution of 0.42% of the mass of sodium element.

[0089] Performance test: Referring to the national standard GB / T 23439-2017 "Concrete Expansion Agent", the limited expansion rate of the cement expansive agent prepared in this embodiment in the air and the 28d compressive strength of the cement mortar specimen added with the expansive agent were tested. The results were: limited expansion rate = -0.039%, 28d compressive strength = 43.72MPa.

[0090] Example 7

[0091] A method for preparing a calcium sulfosilicate cement-based expansion agent comprises the following steps:

[0092] (1) Take the following raw materials in the following weight ratios: 91.30 parts of calcium oxide source (carbide slag), 28.18 parts of Bayer red mud, 11.52 parts of silicon source (fly ash), 10.24 parts of calcium sulfate source (desulfurized gypsum), and 0.95 parts of sodium source (sodium oxide).

[0093] (2) The calcium oxide source, red mud, silicon source, calcium sulfate source and sodium source are mixed uniformly. The raw material is then heated to 1200°C at a heating rate of 10°C / min and calcined for 5 min. After completion, the calcined product is first air-cooled to room temperature and then ground to obtain an expansion source powder, such as Fig.12 shown.

[0094] (3) Take gypsum powder with a mass ratio of 15% of the expansion source powder, mix the two evenly, and obtain component A for later use.

[0095] (4) Take 0.5% by weight of propanolamine of component A and mix the two components evenly to obtain a cement expansion agent.

[0096] The main components of the expansion source powder prepared in this embodiment are measured to include: calcium aluminoferrite (Ca2Al x F 2-xO5), calcium sulfosilicate (C5S2$), dicalcium silicate (C2S) and calcium sulfate (CaSO4). The calculated content of calcium aluminoferrite is 51.78wt.%, the content of calcium sulfosilicate is 32.41wt.%, the content of dicalcium silicate is 8.72wt.%, the content of calcium sulfate is 3.04wt.%, and the rest is the inevitable impurity mineral phase. x F 2-x O5) includes dicalcium ferrite (C2F), hexacalcium dialuminoferrite (C6AF2), tetracalcium aluminoferrite (C4AF), and hexacalcium dialuminoferrite (C6A2F). The calcium sulfosilicate contains 0.17% sodium by weight in solid solution.

[0097] Performance test: Referring to the national standard GB / T 23439-2017 "Concrete Expansion Agent", the limited expansion rate of the cement expansive agent prepared in this embodiment in the air and the 28d compressive strength of the cement mortar specimen added with the expansive agent were tested. The results were: limited expansion rate = -0.013%, 28d compressive strength = 50.41 MPa.

[0098] Example 8

[0099] A method for preparing a calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent comprises the following steps:

[0100] (1) Take the following raw materials in the following weight ratios: 84.31 parts of calcium oxide source (limestone), 26.29 parts of Bayer red mud, 19.11 parts of silicon source (fly ash), 11.32 parts of aluminum source (aluminum ash), 10.18 parts of calcium sulfate source (fluorgypsum), and 1.45 parts of sodium source (sodium carbonate).

[0101] (2) The calcium oxide source, red mud, silicon source, aluminum source, calcium sulfate source and sodium source are mixed uniformly. The raw material is then heated to 1100°C at a heating rate of 10°C / min and calcined for 15 minutes. After completion, the calcined product is first air-cooled to room temperature and then ground to obtain an expansion source powder.

[0102] (3) Take 0.3% of the mass of the expansion source powder and triethanolamine, mix the two evenly, and obtain a cement expansion agent.

[0103] Performance test: Referring to the national standard GB / T 23439-2017 "Concrete Expansion Agent", the limited expansion rate of the cement expansive agent prepared in this embodiment in the air and the 28d compressive strength of the cement mortar specimen added with the expansive agent were tested. The results were: limited expansion rate = -0.021%, 28d compressive strength = 42.29 MPa.

[0104] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent, characterized in that: include: The expansion source powder includes 45-55wt.% of calcium aluminoferrate, 30-40wt.% of calcium sulfosilicate, 5-10wt.% of calcium sulfoaluminate, 5-10wt.% of dicalcium silicate, and 2-4wt.% of calcium sulfate; the remainder is an inevitable impurity mineral phase; the calcium aluminoferrate is composed of dicalcium ferrite, hexacalcium aluminoferrate, tetracalcium aluminoferrate, and hexacalcium aluminoferrate; Gypsum powder, which accounts for 12-18% of the mass of the expansion source powder; The regulating agent is triethanolamine or propanolamine; the regulating agent is 0.1-0.5% of the total mass of the expansion source powder and the gypsum powder.

2. The calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent according to claim 1, characterized in that: The calcium thiosilicate contains a sodium element in solid solution, and the sodium element has a content of 0.1-0.6% of the mass of the calcium thiosilicate.

3. The method for preparing the calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent according to claim 1 or 2, characterized in that: The steps include: (1) The calcium oxide source, red mud, silicon source, aluminum source and calcium sulfate source are mixed evenly and then calcined. After the calcination is completed, the calcined product is sequentially quenched and crushed to obtain an expansion source powder; (2) uniformly mixing the expansion source powder and gypsum powder to obtain component A for later use; (3) The component A is mixed evenly with the regulating agent to obtain the cement expansion agent.

4. The method for preparing the calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent according to claim 3, characterized in that: In step (1), the weight ratio of each raw material is: 81.73-84.86 parts of calcium oxide source, 22.44-32.74 parts of red mud, 12.77-19.11 parts of silicon source, 6.15-11.32 parts of aluminum source, and 8.61-12.13 parts of calcium sulfate source.

5. The method for preparing the calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent according to claim 4, characterized in that: The raw materials also include 0.95-1.45 parts by weight of a sodium source.

6. The method for preparing the calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent according to claim 5, characterized in that: The sodium source includes at least one of sodium oxide, sodium carbonate and sodium hydroxide.

7. The method for preparing the calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent according to claim 3, characterized in that: In step (1), the calcium oxide source includes at least one of limestone, carbide slag, quicklime and calcium hydroxide.

8. The method for preparing the calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent according to claim 5, characterized in that: In step (1), the red mud comprises at least one of Bayer process red mud, sintering process red mud and combined process red mud.

9. The method for preparing the calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent according to claim 5, characterized in that: In step (1), the silicon source includes at least one of sandstone and fly ash.

10. The method for preparing the calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent according to claim 5, characterized in that: In step (1), the aluminum source includes at least one of aluminum ash and bauxite.

11. The method for preparing the calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent according to claim 3, characterized in that: In step (1), the calcium sulfate source includes at least one of phosphogypsum, fluorgypsum, titanium gypsum, desulfurized gypsum, and pure calcium sulfate reagent.

12. The method for preparing the calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent according to any one of claims 3 to 7, characterized in that: In step (1), the calcination temperature is 1100-1200° C., and the calcination time is 5-20 min.

13. The method for preparing the calcium aluminoferrate-calcium sulfosilicate cement-based expansion agent according to any one of claims 3 to 7, characterized in that: In step (1), the rapid cooling method includes any one of wind cooling, air cooling, and liquid nitrogen cooling.

14. Use of the calcium aluminoferrite-calcium sulfosilicate cement-based expansive agent according to claim 1 or 2, or the calcium aluminoferrite-calcium sulfosilicate cement-based expansive agent obtained by the preparation method according to any one of claims 3 to 13 in silicate cement-based cementitious materials.

15. The use according to claim 14, characterized in that: The amount of the expansive agent is 5-15% of the mass of the silicate cement-based cementitious material.

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