A low-carbon high-belliite / high-iron phase mineral material, a preparation method and application thereof

Abstract

The present application relates to a kind of low-carbon high belite / high iron phase mineral materials and its preparation method and application, by mass parts, raw material includes calcareous raw material 90~110 parts, siliceous raw material 0~26 parts, aluminium raw material 2~29 parts, iron raw material 7~45 parts, firing additive 1~5 parts.The present application is with calcareous raw material, siliceous raw material, aluminium raw material and iron raw material as main raw material, by controlling raw material proportion and under the action of firing additive, generate low-carbon high belite / high iron phase mineral materials, the content of belite and iron phase in the mineral material is high, also contain part high cementitious activity α' type dicalcium silicate, can be used as cement mixed material and cement clinker combined grinding to make cement or as admixture directly added in concrete, in keeping the high compressive strength of concrete, reduce hydration heat release, improve the anti-cracking performance, while enhancing the resistance to chloride ion penetration performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of building materials, and particularly relates to a low-carbon high-belite / high-iron phase mineral material and a preparation method and application thereof. BACKGROUND

[0002] As an important building material, Portland cement is widely used in concrete structures. The main phase C3S of Portland cement accounts for about 50-70%. C3S has the characteristics of early strength and fast hardening, but its CaO content is high and the sintering temperature is high, so the corresponding carbon emission and sintering energy consumption are relatively high, and the early hydration heat release is high, which is easy to cause internal stress and cracking. Therefore, in the cement industry, new methods need to be used to reduce carbon emission and sintering energy consumption, and reduce the risk of cement cracking.

[0003] In order to improve the crack resistance and corrosion resistance of cement-based materials and enhance the stability of the structure, it is an extremely important method to control the hydration heat release and aluminum content of cementitious materials. At present, in basic theoretical research, actual production and application, the following methods are mainly used: adjusting the mineral composition of cement clinker, reducing the content of high heat release components such as C3S and C3A, and producing low-heat Portland cement; using a large amount of fly ash, mineral powder and other mineral admixtures to reduce the amount of cement and reduce the occurrence of cracks.

[0004] However, this method has limited ability to reduce the heat release of cement, and greatly affects the setting and hardening of cement-based materials and the strength of cement-based materials. At the same time, the lower the aluminum content in cement, the lower the chloride ion solidification amount, which is not conducive to the development of cement resistance to chloride salt corrosion. Therefore, it is urgent to reduce the heat release of cement by preparing active mineral materials to enhance the crack resistance and corrosion resistance of cement. SUMMARY

[0005] The purpose of the present application is to overcome the above technical deficiencies, provide a low-carbon high-belite / high-iron phase mineral material and a preparation method and application thereof, and solve the technical problem of poor crack resistance and corrosion resistance caused by high hydration heat release of Portland cement in the prior art.

[0006] To achieve the above technical purpose, the technical scheme provided by the present application is as follows:

[0007] In a first aspect, the present application provides a low-carbon high-belite / high-iron phase mineral material, wherein the raw materials include, by mass fraction, 90-110 parts of calcium raw materials, 0-26 parts of silicon raw materials, 2-29 parts of aluminum raw materials, 7-45 parts of iron raw materials, and 1-5 parts of sintering additives.

[0008] In a second aspect, the present application provides a preparation method of a low-carbon high-belite / high-iron phase mineral material, comprising the following steps: crushing and grinding calcium raw material, silicon raw material, aluminum raw material and iron raw material respectively, mixing the crushed and ground raw materials with a sintering additive in proportion to obtain raw meal; and calcining the raw meal, and then cooling, grinding and sieving to obtain the low-carbon high-belite / high-iron phase mineral material.

[0009] In a third aspect, the present application provides an application of the low-carbon high-belite / high-iron phase mineral material as a concrete admixture or a cement mixing material.

[0010] In a fourth aspect, the present application provides a cement prepared by mixing cement clinker and a mixing material, wherein the mixing material is the low-carbon high-belite / high-iron phase mineral material; and the mixing material accounts for 5-80% of the total mass of the cement.

[0011] In a fifth aspect, the present application provides a concrete comprising cement, coarse aggregate, fine aggregate, admixture and water, wherein the admixture is the low-carbon high-belite / high-iron phase mineral material; and the admixture accounts for 5-60% of the total mass of the admixture and the cement.

[0012] Compared with the prior art, the present application has the following beneficial effects:

[0013] The present application uses calcium raw material, silicon raw material, aluminum raw material and iron raw material as main raw meal, adjusts the calcination system under the action of a sintering additive by controlling the proportion of raw materials, so as to generate a low-carbon high-belite / high-iron phase mineral material. The mineral material contains high content of belite and iron phase, and also contains part of high-gelling activity α'-type dicalcium silicate, which can be used as a cement mixing material to be combined with cement clinker for cement grinding or directly added to concrete as an admixture. When added to concrete, the low-carbon high-belite / high-iron phase mineral material can reduce hydration heat while maintaining high compressive strength of the concrete, improve crack resistance, and enhance chloride ion permeability. Therefore, the low-carbon high-belite / high-iron phase mineral material mixed into cement can effectively improve the stability of low-heat and corrosion-resistant products, and is suitable for mass concrete engineering projects in marine environments. At the same time, the preparation method of the low-carbon high-belite / high-iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement is simple, which is conducive to industrial production, and can reduce environmental load while improving the sustainability and durability of cement-based material structure. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is the rock phase distribution of Example 2 of the present application; wherein 1: β C2S; 2: C4AF; 3: C3A. DETAILED DESCRIPTION

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0016] Currently, silicate cement suffers from high hydration heat release, resulting in poor crack and corrosion resistance. Simply adjusting the mineral composition of cement clinker has a limited effect on reducing the heat release of cement and can affect its mechanical properties, leading to low strength. Therefore, existing technologies cannot reduce the heat release of cement while ensuring strength and enhancing its crack and corrosion resistance. Based on this, the present invention is established.

[0017] In a first aspect, the present invention provides a low-carbon, high-belite / high-iron phase mineral material, which, by mass, comprises 90-110 parts of calcium raw material, 0-26 parts of silicon raw material, 2-29 parts of aluminum raw material, 7-45 parts of iron raw material, and 1-5 parts of calcination additives.

[0018] Preferably, based on oxides, the CaO content in the calcium-based raw material is above 45%, the SiO2 content in the silicon-based raw material is above 80%, the Al2O3 content in the aluminum-based raw material is above 20%, and the Fe2O3 content in the iron-based raw material is above 30%.

[0019] Preferably, the calcareous raw materials include limestone, carbide slag, and steel slag; the siliceous raw materials include high-silica sandstone and coal gangue; the aluminous raw materials include secondary alumina ash and red mud; and the ferrous raw materials include iron tailings, copper slag, and steel slag. Limestone is preferably used as the calcareous raw material in the mineral raw materials; high-silica sandstone, with its extremely high silica content, serves as a siliceous raw material without the need for additional corrective materials, and its close intermolecular contact and fine particles have minimal impact on grindability, thus facilitating calcination; secondary alumina ash is a byproduct of the aluminum industry and can be used as an aluminum raw material to promote the resource utilization of solid waste in the building materials industry; and iron tailings, a metallurgical industrial waste, can be used as an ferrous raw material in the mineral raw materials.

[0020] Preferably, the calcination additives include minerals containing one or more elements selected from boron, phosphorus, magnesium, and fluorine.

[0021] Further preferred, the boron-containing mineral includes borax.

[0022] Preferably, the phase composition of the low-carbon high-belite / high-iron phase mineral material formed by calcination is obtained by Rietveld refinement using High Score software, and the composition includes: tricalcium silicate (C3S) 0-6%, dicalcium silicate 25%-79%, tricalcium aluminate (C3A) 0-2%, and iron phase (one or more of C4AF, C6AF2 or C6A2F) 18%-75%.

[0023] Further preferred, dicalcium silicate includesβ β-dicalcium silicate and α β-dicalcium silicate; the mineralogical composition of the low-carbon high belite / high-iron phase mineral material includes: tricalcium silicate (C3S) 0-1.8%, β β-dicalcium silicate β -C2S) 23.5%-69.8%, α β-dicalcium silicate α '-C2S) 5.1%-9.1%, tricalcium aluminate (C3A) 0-1.5%, iron phase (one or more of C4AF, C6AF2 or C6A2F) 18.6%-66.8%.

[0024] In a second aspect, the present application provides a preparation method of a low-carbon high belite / high-iron phase mineral material, comprising the following steps:

[0025] The calcareous raw material, siliceous raw material, aluminous raw material and ferruginous raw material are respectively crushed and finely ground, and then mixed with the sintering additive in proportion to obtain a raw material;

[0026] The raw material is calcined, and then cooled, ground and sieved to obtain the low-carbon high belite / high-iron phase mineral material.

[0027] Preferably, the crushing is crushing into particles with a particle size of ≤5 mm; and the finely grinding is grinding to a powder particle size of ≤75 μm.

[0028] Preferably, the calcination temperature is 1200 ℃-1350 ℃, and the time is 30-120 min.

[0029] Preferably, the cooling is air cooling to room temperature.

[0030] In a third aspect, the present application provides an application of the low-carbon high belite / high-iron phase mineral material as a concrete admixture or cement mixture.

[0031] In a fourth aspect, the present application provides a cement prepared by mixing a cement clinker and a mixture, wherein the mixture is the low-carbon high belite / high-iron phase mineral material; and the mixture accounts for 5-80% of the total mass of the cement (i.e. the total mass of the mixture and the cement clinker).

[0032] The low-carbon high belite / high-iron phase mineral material obtained by the present application can be used as a cement mixture to be ground together with a cement clinker to prepare cement.

[0033] Preferably, the cement clinker includes one or more of Portland cement clinker, ferrum-aluminate cement clinker and sulpho-aluminate cement clinker.

[0034] Preferably, the cement clinker includes one or more of moderate-heat cement clinker and low-heat cement clinker.

[0035] In a fifth aspect, the present application provides a concrete, comprising cement, coarse aggregate, fine aggregate, admixture and water, wherein the admixture is the low-carbon high belite / high-iron phase mineral material described above; the admixture accounts for 5-60% of the total mass of the admixture and cement.

[0036] Preferably, the high belite / high-iron phase mineral materials with different aluminum-iron ratios prepared within the above range can be mixed with each other at any ratio as a composite active admixture to effectively improve the crack resistance and corrosion resistance of the system.

[0037] Mechanism of action and advantages of the present application:

[0038] (1) The principle that the low-carbon high belite / high-iron phase mineral material of the present application can enhance the crack resistance and corrosion resistance of cement is based on the composition and reaction process of the mineral phases in cement clinker. The present application uses limestone, high-silicon sandstone, secondary aluminum ash, and iron tailings as raw materials, and borax as a sintering additive, to produce high belite / high-iron phase mineral materials. The content of belite and iron phase in the mineral material is high. Among them, the belite / iron phase refers to a specific mineral phase in the clinker, mainly including β C2S and iron phase (one of C4AF, C6AF2 and C6A2F), and part of high-gelatinous α'-type dicalcium silicate. These mineral phases have extremely low C3S content, low synthesis temperature, and can effectively reduce the heat release of cement-based materials when added as an admixture to cement. In the middle and later stages of the hydration process, they continue to react and still form a large amount of hydration products, such as hydrated calcium silicate (C-S-H) gel and hydrated calcium aluminate. These gels have high gelatinous and crystalline activity and can form a dense hydration product structure. And the different active calcium aluminates designed by reasonable matching can continuously solidify chloride ions, effectively enhancing the crack resistance and corrosion resistance of cement.

[0039] (2) The low-carbon high belite / high-iron phase mineral material of the present application has excellent sinterability, with a calcination temperature of 1200-1350°C. The lower decomposition and calcination temperature makes it have a significant energy-saving and emission-reducing effect compared to traditional cement clinker. In the production process, the coal consumption and carbon emissions of the clinker are reduced, the impact on the environment is smaller, and the production cost of the clinker is also reduced, which has the characteristics of being economical and practical.

[0040] (3) The low-carbon high-belite / high-iron phase mineral material fully plays a synergistic effect of belite and iron phase minerals. In the middle and later hydration process, the belite has a high strength growth rate, low hydration heat, and good water resistance, and the iron phase continues to grow in strength in the later stage, and has good resistance to chloride salt. After matching the composition of the two minerals, reasonably controlling the aluminum / iron ratio and the amount of the iron phase mineral, and directly adding the active admixture to the existing bulk Portland cement, not only can the cement hydration heat be greatly reduced, and the cracking of Portland cement can be reduced, but also the aluminum dissolution rate can be controlled, and the mechanical properties and erosion resistance of the cement can be improved according to the difference in the reaction activity in the cement hydration process.

[0041] In summary, the present application solves the defects of high carbon emission and poor permeability resistance of Portland cement products from the source, and provides a low-carbon high-belite / high-iron phase mineral material for enhancing the crack resistance and erosion resistance of cement; the low-carbon high-belite / high-iron phase mineral material can be used as a cement admixture or as a concrete admixture. When added to concrete, the compressive strength of the concrete is maintained, the hydration heat is reduced, the crack resistance is improved, the chloride ion permeability resistance is enhanced, the engineering application performance of the high-belite / high-iron phase cement mineral material is expanded, and the service life of the engineering structure is prolonged.

[0042] The present application will be further described in detail below with specific examples. The limestone, high-silicon sandstone, secondary aluminum ash and iron tailings are crushed into particles with a particle size of ≤5 mm, and then ground into powders with a particle size of ≤75 μm using a ball mill, and the chemical composition of the raw materials is shown in Table 1.

[0043] Table 1 Chemical composition of each raw material (%)

[0044]

[0045] Example 1

[0046] (1) The limestone 110 parts, high-silicon sandstone 25 parts, secondary aluminum ash 5 parts, iron tailings 11 parts and borax 3 parts are mixed as uniform raw materials according to the mineral design composition of the mineral material; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 80%, iron phase (C4AF) 20%;

[0047] (2) The raw material is calcined at 1300 ℃ for 120 min, and then rapidly cooled (rapidly cooled to room temperature by air);

[0048] (3) The average particle size of the clinker mineral after grinding and screening is 15 μm, and the low-carbon high-belite / high-iron phase mineral material for enhancing the crack resistance and erosion resistance of cement is obtained.

[0049] Example 2

[0050] (1) Limestone 106 parts, high silica sandstone 20 parts, secondary aluminum ash 8 parts, iron tailings 17 parts and borax 3 parts are mixed as uniform raw meal according to the mineral design composition of the mineral material; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 70%, iron phase (C4AF) 30%;

[0051] (2) The raw meal is calcined at 1300 ℃ for 120 min, and then rapidly cooled;

[0052] (3) After the clinker mineral is ground and sieved, the average particle size is 15 μm, and a low-carbon high belite / high iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement is obtained.

[0053] Example 3

[0054] (1) Limestone 102 parts, high silica sandstone 15 parts, secondary aluminum ash 11 parts, iron tailings 22 parts and borax 2 parts are mixed as uniform raw meal according to the mineral design composition of the mineral material; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 60%, iron phase (C4AF) 40%;

[0055] (2) The raw meal is calcined at 1300 ℃ for 120 min, and then rapidly cooled;

[0056] (3) After the clinker mineral is ground and sieved, the average particle size is 15 μm, and a low-carbon high belite / high iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement is obtained.

[0057] Example 4

[0058] (1) Limestone 98 parts, high silica sandstone 10 parts, secondary aluminum ash 14 parts, iron tailings 28 parts and borax 2 parts are mixed as uniform raw meal according to the mineral design composition of the mineral material; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 50%, iron phase (C4AF) 50%;

[0059] (2) The raw meal is calcined at 1240 ℃ for 120 min, and then rapidly cooled;

[0060] (3) After the clinker mineral is ground and sieved, the average particle size is 15 μm, and a low-carbon high belite / high iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement is obtained.

[0061] Example 5

[0062] (1) Limestone 94 parts, high silica sandstone 4 parts, secondary aluminum ash 17 parts, iron tailings 34 parts and borax 1 part are mixed as uniform raw meal according to the mineral design composition of the mineral material; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 40%, iron phase (C4AF) 60%;

[0063] (2) The raw meal is calcined at 1240 °C for 120 min, and then rapidly cooled;

[0064] (3) The average particle size of the ground and sieved clinker mineral is 15 μm, obtaining the low-carbon high belite / high iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement.

[0065] Example 6

[0066] (1) According to the mineral design composition of the mineral material, limestone 92 parts, high-silicon sandstone 1 part, secondary aluminum ash 19 parts, iron tailings 37 parts and borax 1 part are mixed into uniform raw meal; the mineral mass composition of the designed mineral material includes: tricalcium silicate (C3S) 3%, dicalcium silicate (C2S) 30%, tricalcium aluminate (C3A) 1%, iron phase (C4AF) 66%;

[0067] (2) The raw meal is calcined at 1240 °C for 120 min, and then rapidly cooled;

[0068] (3) The average particle size of the ground and sieved clinker mineral is 15 μm, obtaining the low-carbon high belite / high iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement.

[0069] Example 7

[0070] (1) According to the mineral design composition of the mineral material, limestone 109 parts, high-silicon sandstone 25 parts, secondary aluminum ash 2 parts, iron tailings 14 parts and borax 3 parts are mixed into uniform raw meal; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 80%, iron phase (C6AF2) 20%;

[0071] (2) The raw meal is calcined at 1240 °C for 120 min, and then rapidly cooled;

[0072] (3) The average particle size of the ground and sieved clinker mineral is 15 μm, obtaining the low-carbon high belite / high iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement.

[0073] Example 8

[0074] (1) According to the mineral design composition of the mineral material, limestone 105 parts, high-silicon sandstone 19 parts, secondary aluminum ash 4 parts, iron tailings 22 parts and borax 3 parts are mixed into uniform raw meal; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 70%, iron phase (C6AF2) 30%;

[0075] (2) The raw meal is calcined at 1240 °C for 120 min, and then rapidly cooled;

[0076] (3) The average particle size of the ground and sieved clinker mineral is 15 μm, obtaining the low-carbon high belite / high iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement.

[0077] Example 9

[0078] (1) According to the mineral design composition of the mineral material, limestone 101 parts, high-silicon sandstone 13 parts, secondary aluminum ash 5 parts, iron tailings 29 parts and borax 2 parts are mixed into uniform raw meal; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 60%, iron phase (C6AF2) 40%;

[0079] (2) The raw meal is calcined at 1240 °C for 120 min, and then rapidly cooled;

[0080] (3) After the clinker mineral is ground and sieved, the average particle size is 15 μm, obtaining a low-carbon high belite / high iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement.

[0081] Example 10

[0082] (1) According to the mineral design composition of the mineral material, limestone 97 parts, high-silicon sandstone 8 parts, secondary aluminum ash 7 parts, iron tailings 37 parts and borax 2 parts are mixed into uniform raw meal; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 50%, iron phase (C6AF2) 50%;

[0083] (2) The raw meal is calcined at 1200 °C for 120 min, and then rapidly cooled;

[0084] (3) After the clinker mineral is ground and sieved, the average particle size is 15 μm, obtaining a low-carbon high belite / high iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement.

[0085] Example 11

[0086] (1) According to the mineral design composition of the mineral material, limestone 92 parts, high-silicon sandstone 2 parts, secondary aluminum ash 9 parts, iron tailings 44 parts and borax 1 part are mixed into uniform raw meal; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 40%, iron phase (C6AF2) 60%;

[0087] (2) The raw meal is calcined at 1200 °C for 120 min, and then rapidly cooled;

[0088] (3) After the clinker mineral is ground and sieved, the average particle size is 15 μm, obtaining a low-carbon high belite / high iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement.

[0089] Example 12

[0090] (1) According to the mineral design composition of the mineral material, limestone 92 parts, secondary aluminum ash 10 parts, iron tailings 45 parts and borax 1 part are mixed into uniform raw meal; the mineral mass composition of the designed mineral material includes: tricalcium silicate (C3S) 3%, dicalcium silicate (C2S) 34%, tricalcium aluminate (C3A) 1%, iron phase (C6AF2) 62%;

[0091] (2) The raw meal is calcined at 1200 ℃ for 120 min, and then rapidly cooled;

[0092] (3) After the clinker mineral is ground and sieved, the average particle size is 15 μm, and a low-carbon high belite / high iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement is obtained.

[0093] Example 13

[0094] (1) According to the mineral design composition of the mineral material, limestone 110 parts, high-silicon sandstone 26 parts, secondary aluminum ash 8 parts, iron tailings 7 parts and borax 3 parts are mixed into uniform raw meal; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 80%, iron phase (C6A2F) 20%;

[0095] (2) The raw meal is calcined at 1350 ℃ for 120 min, and then rapidly cooled;

[0096] (3) After the clinker mineral is ground and sieved, the average particle size is 15 μm, and a low-carbon high belite / high iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement is obtained.

[0097] Example 14

[0098] (1) According to the mineral design composition of the mineral material, limestone 107 parts, high-silicon sandstone 21 parts, secondary aluminum ash 12 parts, iron tailings 11 parts and borax 3 parts are mixed into uniform raw meal; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 70%, iron phase (C6A2F) 30%;

[0099] (2) The raw meal is calcined at 1350 ℃ for 120 min, and then rapidly cooled;

[0100] (3) After the clinker mineral is ground and sieved, the average particle size is 15 μm, and a low-carbon high belite / high iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement is obtained.

[0101] Example 15

[0102] (1) According to the mineral design composition of the mineral material, limestone 103 parts, high-silicon sandstone 17 parts, secondary aluminum ash 16 parts, iron tailings 15 parts and borax 2 parts are mixed into uniform raw meal; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 60%, iron phase (C6A2F) 40%;

[0103] (2) The raw meal is calcined at 1350 °C for 120 min, followed by quenching;

[0104] (3) The average particle size of the ground and sieved clinker minerals is 15 μm, obtaining the low-carbon high belite / high-iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement.

[0105] Example 16

[0106] (1) Limestone 99 parts, high-silicon sandstone 12 parts, secondary aluminum ash 21 parts, iron tailings 19 parts and borax 2 parts are mixed as uniform raw meal according to the mineral design composition of the mineral material; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 50%, iron phase (C6A2F) 50%;

[0107] (2) The raw meal is calcined at 1270 °C for 120 min, followed by quenching;

[0108] (3) The average particle size of the ground and sieved clinker minerals is 15 μm, obtaining the low-carbon high belite / high-iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement.

[0109] Example 17

[0110] (1) Limestone 96 parts, high-silicon sandstone 7 parts, secondary aluminum ash 25 parts, iron tailings 23 parts and borax 1 part are mixed as uniform raw meal according to the mineral design composition of the mineral material; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 40%, iron phase (C6A2F) 60%;

[0111] (2) The raw meal is calcined at 1270 °C for 120 min, followed by quenching;

[0112] (3) The average particle size of the ground and sieved clinker minerals is 15 μm, obtaining the low-carbon high belite / high-iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement.

[0113] Example 18

[0114] (1) Limestone 92 parts, high-silicon sandstone 2 parts, secondary aluminum ash 29 parts, iron tailings 27 parts and borax 1 part are mixed as uniform raw meal according to the mineral design composition of the mineral material; the mineral mass composition of the designed mineral material includes: dicalcium silicate (C2S) 30%, iron phase (C6A2F) 70%.

[0115] (2) The raw meal is calcined at 1270 °C for 120 min, followed by quenching;

[0116] (3) The average particle size of the ground and sieved clinker minerals is 15 μm, obtaining the low-carbon high belite / high-iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement.

[0117] To highlight the final mineral composition change of the mineral material, the comparative example test is set by the raw material and the calcination temperature synergistic change. The mineral mass of the mineral material is designed by referring to the general Portland cement clinker mineral composition.

[0118] Comparative Example 1

[0119] (1) According to the mineral composition of the mineral material, 123 parts of limestone, 22 parts of high-silicon sandstone, 7 parts of secondary aluminum ash, and 5 parts of iron tailings are mixed into uniform raw materials. The mineral mass composition of the mineral material includes: tricalcium silicate (C3S) 62%, dicalcium silicate (C2S) 20%, tricalcium aluminate (C3A) 8%, and iron phase (C4AF) 10%.

[0120] (2) The raw materials are calcined at 1430 ℃ for 120 min, and then rapidly cooled;

[0121] (3) After the clinker minerals are ground, the average particle size is 15 μm, and the low-carbon high-belite / high-iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement is obtained.

[0122] Comparative Example 2

[0123] (1) According to the mineral composition of the mineral material, 123 parts of limestone, 22 parts of high-silicon sandstone, 5 parts of secondary aluminum ash, and 7 parts of iron tailings are mixed into uniform raw materials. The mineral mass composition of the mineral material includes: tricalcium silicate (C3S) 62%, dicalcium silicate (C2S) 20%, tricalcium aluminate (C3A) 8%, and iron phase (C6AF2) 10%.

[0124] (2) The raw materials are calcined at 1400 ℃ for 120 min, and then rapidly cooled;

[0125] (3) After the clinker minerals are ground, the average particle size is 15 μm, and the low-carbon high-belite / high-iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement is obtained.

[0126] Comparative Example 3

[0127] (1) According to the mineral composition of the mineral material, 123 parts of limestone, 22 parts of high-silicon sandstone, 8 parts of secondary aluminum ash, and 4 parts of iron tailings are mixed into uniform raw materials. The mineral mass composition of the mineral material includes: tricalcium silicate (C3S) 62%, dicalcium silicate (C2S) 20%, tricalcium aluminate (C3A) 8%, and iron phase (C6A2F) 10%.

[0128] (2) The raw materials are calcined at 1450 ℃ for 120 min, and then rapidly cooled;

[0129] (3) After the clinker minerals are ground, the average particle size is 15 μm, and the low-carbon high-belite / high-iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement is obtained.

[0130] Performance testing

[0131] 1. The phase composition of the low-carbon high-belite / high-iron phase mineral material formed by calcination was obtained by Rietveld refinement using High Score software; and the design composition of the low-carbon high-belite / high-iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement obtained in the above examples and comparative examples and the Rietveld refinement results were statistically analyzed. The results are shown in Table 2 below.

[0132] Table 2. Design composition of low-carbon high-belite / high-ferrous phase mineral materials and Rietveld refinement results (%)

[0133]

[0134] As shown in Table 2, the mineral composition of the low-carbon high-belite / high-iron phase mineral material obtained in this invention includes: tricalcium silicate (C3S) 0-1.8%, β Type dicalcium silicate ( β -C2S) 23.5%~69.8%, α 'type dicalcium silicate ( α The mineral composition of the samples was 5.1%–9.1% (-C2S), 0–1.5% (tricalcium aluminate (C3A), and 18.6%–66.8% (one or more of C4AF, C6AF2, or C6A2F). In contrast, the main mineral component of the comparative examples 1–3 was tricalcium silicate.

[0135] 2. Petrographic analysis was performed on the low-carbon, high-belite / high-ferrous phase mineral material obtained in Example 4. The results are as follows: Figure 1 As shown, it can be seen that it generated a large number of... β -C2S(1) and C4AF(2), and a small amount of C3A(3).

[0136] 3. Performance tests were conducted on C45 concrete prepared using the low-carbon, high-belite / high-ferrite phase mineral materials obtained in the above examples and comparative examples as admixtures to enhance the crack and corrosion resistance of cement. The mix design is shown in Table 3. The control group consisted of tests without mineral materials. The low-carbon, high-belite / high-ferrite phase mineral materials obtained in the examples and comparative examples replaced 20% of the cement mass as admixtures. P·I 42.5 cement was used. Medium sand with a fineness modulus of 2.8 was used. Clean crushed stone with a two-gradation of 5-10 mm and 10-31.5 mm, good particle shape, hard texture, and low coefficient of linear expansion was used. An appropriate amount of polycarboxylate-based high-performance water-reducing agent was selected to regulate workability; its solid content was 30%, and its water reduction rate was 30%. Tap water was used.

[0137] Table 3. C45 Concrete Mix Design (kg / m³)3 )

[0138]

[0139] The prepared C45 concrete was standard cured for 28 d and 56 d, and performance tests were performed, the compressive strength and the adiabatic temperature rise test were performed according to GB / T 50080-2016, and the chloride ion permeability coefficient was performed according to GB / T 50082-2009, and the results are shown in Table 4.

[0140] Table 4 Concrete performance test results of the mineral materials obtained in each example and the comparative examples

[0141]

[0142] As can be seen from Table 4, compared with the control group, the low-carbon high belite / high-iron phase mineral material used as an admixture in each example can significantly improve the strength after 28 d, and the 28 d adiabatic temperature rise and the chloride ion permeability coefficient are significantly lower than those of the control group.

[0143] Compared with each comparative example and the control group, the iron phase component in the admixture is converted into C4AF, C6AF2 and C6A2F by adjusting the component ratio and the calcination temperature, and as an admixture, it can stabilize or improve the compressive strength of the concrete material, but the 28 d adiabatic temperature rise and the chloride ion permeability coefficient are not reduced, and the crack resistance and corrosion resistance are poor.

[0144] Compared with each example and the comparative example, the low-carbon high belite / high-iron phase mineral material used as an admixture has extremely low C3S and C3A content, but the strength after 28 d is significantly improved, and the 28 d adiabatic temperature rise and the chloride ion permeability coefficient are significantly lower than those of the comparative example, and the crack resistance and corrosion resistance are excellent.

[0145] Compared with Examples 1-6, the iron phase content in the admixture gradually increases, the C2S content gradually decreases, the adiabatic temperature rise has a slight increasing effect, the strength after 28 d is slightly reduced, but the chloride ion permeability performance is improved. The same applies to Examples 7-12 and Examples 13-18.

[0146] Compared with Examples 1-6, Examples 7-12 and Examples 13-18, the aluminum content increases and the iron content decreases in the admixture with the same mineral component ratio, which has a slight increasing effect on the compressive strength, but weakens the adiabatic temperature rise inhibition and the chloride ion permeability inhibition.

[0147] The low-carbon high belite / high-iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement disclosed in the application can effectively improve the crack resistance and corrosion resistance of concrete by regulating the content of belite / iron phase and the content of aluminum and iron in the iron phase in a suitable range, and serving as a concrete admixture, while ensuring high strength (28d compressive strength of 53.5-62.8 MPa, 56d compressive strength of 59.0-65.1 MPa), improving crack resistance (28d adiabatic temperature rise of 38.5-49.2 ℃), and enhancing the resistance to chloride ion penetration (28d chloride ion penetration coefficient of 1.32x10 -12 m 2 / s~2.90x10 -12 m 2 / s). The high crack resistance is due to the increase of low heat release mineral C2S content in the system, the high corrosion resistance is due to the formation of iron phase with different aluminum-iron ratios, which regulates the entry of Al into the hydration products during the hydration process to form C-(A,F)-H, and improves the adsorption of chloride ions in the system, expands the engineering application performance of high belite / high-iron phase cement mineral material, and prolongs the service life of engineering structure.

[0148] Therefore, the application provides a low-carbon high belite / high-iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement, which can be directly added to concrete as an admixture, has low hydration heat release, high strength in the middle and later stages, and low chloride ion penetration coefficient, and can improve the stability of low-heat and corrosion-resistant products when mixed into cement, and is suitable for mass concrete engineering projects in marine environments. Meanwhile, the preparation method of the low-carbon high belite / high-iron phase mineral material for enhancing the crack resistance and corrosion resistance of cement has a low synthesis temperature, which is beneficial to industrial production.

[0149] The specific embodiments of the application described above do not constitute a limitation on the scope of protection of the application. Any various other corresponding changes and modifications made according to the technical concept of the application shall be included in the scope of protection of the claims of the application.

Claims

1. A low carbon high belite / high iron phase mineral material, characterized in that, The raw materials include calcium raw material 90-110 parts by mass, silicon raw material 0-26 parts by mass, aluminum raw material 2-29 parts by mass, iron raw material 7-45 parts by mass, and sintering additive 1-5 parts by mass; The CaO content in the calcium raw material is above 45% in terms of oxides, the SiO2 content in the silicon raw material is above 80% in terms of oxides, the Al2O3 content in the aluminum raw material is above 20% in terms of oxides, and the Fe2O3 content in the iron raw material is above 30% in terms of oxides; The calcium raw material includes one or more of limestone, carbide slag and steel slag, the silicon raw material includes one or more of sandstone and coal gangue, the aluminum raw material includes one or more of secondary aluminum ash and red mud, and the iron raw material includes one or more of iron tailings, copper slag and steel slag; The phase composition of the low-carbon high-belite / high-iron phase mineral material includes 0-6% of tricalcium silicate, 25-79% of dicalcium silicate, 0-2% of tricalcium aluminate and 18-75% of iron phase. The sintering additive includes a mineral containing one or more of boron, phosphorus, magnesium and fluorine.

2. The method for preparing low-carbon, high-belite / high-iron phase mineral materials as described in claim 1, characterized in that, The method includes the following steps: The calcium raw material, the silicon raw material, the aluminum raw material and the iron raw material are respectively crushed and finely ground, and then mixed with the sintering additive in proportion to obtain raw meal; The raw meal is calcined, and then cooled, ground and sieved to obtain the low-carbon high-belite / high-iron phase mineral material.

3. The method for preparing low-carbon high-belite / high-iron phase mineral materials according to claim 2, characterized in that, The crushing is crushing into particles with a particle size of ≤5 mm, and the finely grinding is grinding to a powder particle size of ≤75 μm; The calcination temperature is 1200-1350 ℃, and the calcination time is 30-120 min.

4. Use of the low-carbon high-belite / high-iron phase mineral material according to claim 1 as a concrete admixture or cement mixture.

5. Cement, characterized in that The mixture is prepared by mixing cement clinker and mixture, the mixture is the low-carbon high-belite / high-iron phase mineral material according to claim 1, and the mixture accounts for 5-80% of the total mass of the cement.

6. A concrete, characterized by The raw materials include cement, coarse aggregate, fine aggregate, admixture and water, the admixture is the low-carbon high-belite / high-iron phase mineral material according to claim 1, and the admixture accounts for 5-60% of the total mass of the admixture and the cement.

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