Modified ferruginous mineral material for improving the wear and corrosion resistance of cement and method for its production

Abstract

The application discloses a modified ferruginous mineral material for improving wear resistance and corrosion resistance of cement and a preparation method of the modified ferruginous mineral material, and raw materials include calcium components 40-70%, aluminum components 5-30%, ferruginous components 5-30% and active regulators 0-5% in percentage of mass. The modified ferruginous mineral material for improving wear resistance and corrosion resistance of cement can significantly improve cement chloride solidification capacity, wear resistance, reduce the probability of steel surface corrosion by chloride ions, and achieve the purposes of steel corrosion prevention and cement wear resistance in reinforced concrete when the modified ferruginous mineral material is added into cement as admixture.

Description

Technical Field

[0001] This invention belongs to the field of building materials, specifically relating to a modified ferrous mineral material and its preparation method for improving the wear resistance and corrosion resistance of cement. Background Technology

[0002] Concrete possesses excellent compressive strength but poor flexural strength; reinforcing steel exhibits superior tensile and flexural strength. Therefore, reinforced concrete systems are currently the most widely used structural systems. Reinforced concrete structures are widely used in building construction, road construction, bridge construction, and tunnel construction. However, chloride ions migrate to the surface of the reinforcing steel, causing electrochemical corrosion. This corrosion forms iron oxide on the steel surface, leading to internal stress in the concrete and ultimately causing cracking and spalling of the reinforced concrete structure. Simultaneously, increased wear on the concrete surface reduces the chloride ion diffusion distance, increasing the likelihood of steel corrosion. Reinforced concrete failure poses significant safety hazards and causes substantial economic losses.

[0003] To improve the stability of reinforced concrete structures, enhancing the wear resistance and chloride ion solidification resistance of cement is crucial. Cement has limited ability to solidify chloride ions, hence the development of cement admixtures. Cement solidifies chloride ions primarily through two pathways: 1. Physical solidification, where chloride ions solidify through gels generated during cement hydration (mainly calcium silicate hydrate gel, aluminum hydroxide gel, and ferric hydroxide gel). This method has low solidification efficiency and unstable solidification. 2. Chemical solidification, where chloride ions react with cement hydration products to form stable compounds (3CaO·[Al2O3, Fe2O3]·CaCl2·10H2O). Chemical solidification has high efficiency and structural stability. Therefore, increasing the aluminum content in the active minerals of the cement system plays a vital role in resisting chloride ion solidification.

[0004] However, simply increasing the aluminum content in pure cement increases the tricalcium aluminate content, which greatly affects the cement's setting process, causing volume expansion and thus deteriorating its performance. Therefore, significantly increasing the aluminum content in cement is harmful. Currently, among the most widely used mineral admixtures: mineral powder has low aluminum content and limited curing ability; fly ash has poor activity, a slow aluminum release rate, and poor resistance to chloride ions. Therefore, it is urgent to improve the wear resistance and chloride ion resistance of cement by preparing active mineral admixtures. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a modified ferrous mineral material and its preparation method for improving the wear resistance and corrosion resistance of cement, thereby solving the technical problem that mineral admixtures in the prior art are unable to simultaneously improve the wear resistance and chloride ion resistance of cement.

[0006] To achieve the above-mentioned technical objectives, the technical solution provided by this invention is as follows:

[0007] In a first aspect, the present invention provides a modified ferrous mineral material for improving the wear resistance and corrosion resistance of cement. The raw materials, by mass percentage, include 40-70% calcium component, 5-30% aluminum component, 5-30% ferrous component, and 0-5% activity regulator.

[0008] Secondly, the present invention provides a method for preparing a modified ferrous mineral material that improves the wear resistance and corrosion resistance of cement, comprising the following steps: mixing raw materials in proportion to form a uniform raw meal; calcining the raw meal to obtain clinker; rapidly cooling the clinker to form an active mineral; and crushing the active mineral to obtain the modified ferrous mineral material that improves the wear resistance and corrosion resistance of cement.

[0009] Compared with the prior art, the beneficial effects of the present invention include:

[0010] The modified ferrous mineral material obtained in this invention, which improves the wear resistance and corrosion resistance of cement, significantly enhances the cement's chloride ion curing ability while improving wear resistance and reducing the probability of chloride ion corrosion on the surface of reinforcing steel. Simultaneously, this mineral admixture exhibits controllable activity, a wide range of applications, and provides a certain level of later-stage strength. Compared to traditional admixtures (fly ash, mineral powder), this mineral possesses high activity and wear resistance, while ensuring that the later-stage strength of the cement does not decline. Therefore, the modified ferrous mineral material of this invention, when added to cement as an admixture, can achieve the goals of reinforcing steel corrosion prevention and cement wear resistance in reinforced concrete.

[0011] Furthermore, by controlling the mass ratio of alumina and iron oxide, the present invention fires different active minerals to control the release rate of aluminum elements and achieve phased solidification of chloride ions. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0013] This invention mainly achieves rapid aluminum dissolution by firing active admixtures; by adding iron elements to the admixtures and firing them to form admixtures with wear-resistant properties, thereby enhancing the wear resistance of cement; the modified iron mineral materials of this invention, when added to cement as admixtures, can achieve the purpose of steel reinforcement corrosion prevention and cement wear resistance in reinforced concrete.

[0014] This invention provides a modified ferrous mineral material for improving the wear resistance and corrosion resistance of cement. By weight, the raw materials include 40-70 parts of calcium carbonate, 5-30 parts of alumina, 5-30 parts of iron oxide, and 0-5 parts of an activity regulator.

[0015] This invention provides a method for preparing modified ferrous mineral materials that improve the wear resistance and corrosion resistance of cement, comprising the following steps:

[0016] 1) Mix calcium carbonate, aluminum oxide, iron oxide and activity regulator into a uniform raw material;

[0017] 2) The uniformly mixed raw materials are calcined at 1100–1350℃ for 0.5–3 hours to produce clinker;

[0018] 3) Rapid cooling of clinker transforms it into active minerals;

[0019] 4) Grinding active minerals yields modified iron mineral materials that improve the wear resistance and corrosion resistance of cement.

[0020] Preferably, by mass ratio, alumina:iron oxide = A; 1 < A ≤ 6 yields iron-containing mineral material X with a high aluminum-iron ratio, and 0.2 ≤ A ≤ 1 yields iron-containing mineral material Y with a low aluminum-iron ratio. This invention, by sintering minerals with different aluminum-iron ratios, achieves varying reactivity during cement hydration when used as admixtures, thereby controlling the aluminum release rate and realizing phased chloride ion solidification. For example, early chloride ion solidification can be achieved in seawater-mixed concrete; using low-activity minerals in road concrete achieves excellent chloride ion solidification capabilities, and the later hydration products can densely fill the voids in the cement, while the generated ferric hydroxide colloid enhances wear resistance.

[0021] Further preferred, the modified iron mineral material includes materials X and Y in any proportion, that is, the modified iron mineral material can be compounded in any proportion as a composite admixture.

[0022] Preferably, the average particle size of mineral powder with a high alumina:iron oxide ratio is no greater than 70 μm, and the average particle size of mineral powder with a low alumina:iron oxide ratio is less than 20 μm.

[0023] Preferably, the activity regulator is a combination of one or more sulfates and fluorides.

[0024] Preferably, the sulfate comprises one or any combination thereof of sodium sulfate, potassium sulfate, and calcium sulfate; the fluoride is calcium fluoride.

[0025] Preferably, the rapid cooling method includes air cooling, oil cooling, or liquid nitrogen cooling; wherein, for air cooling: 100-200℃ / min for 1350-900℃, and a cooling rate of not less than 70℃ / min for below 900℃; for oil cooling: 150-300℃ / min for 1350-900℃, and a cooling rate of not less than 100℃ / min for below 900℃; for liquid nitrogen cooling: 300-500℃ / min for 1350-900℃, and a cooling rate of not less than 100℃ / min for below 900℃.

[0026] The present invention will be further described in detail below through specific embodiments.

[0027] Comparative Example 1

[0028] 1) Mix 60 wt.% calcium carbonate, 10 wt.% aluminum oxide, 20 wt.% iron oxide, and 10 wt.% silicon oxide into a homogeneous raw material;

[0029] 2) Calcination of raw materials after uniform mixing: The heating rate is 10℃ / min at 30-900℃, the holding time at 900℃ is 60min, the heating rate is 5℃ / min at 900-1350℃, and the holding time at the firing temperature (1350℃) is 1h.

[0030] 3) Rapid cooling of clinker to form highly active minerals: Air cooling rate: not less than 150℃ / min for 1350-900℃, and not less than 70℃ / min for temperatures below 900℃;

[0031] 4) Grinding clinker minerals: The average particle size of the clinker minerals after grinding is 20μm, and the clinker powder is stored at a humidity of 30%; thus, modified iron mineral materials that improve the wear resistance and corrosion resistance of cement are obtained.

[0032] Example 1

[0033] 1) Mix 60 wt.% calcium carbonate, 15 wt.% aluminum oxide, and 25 wt.% iron oxide into a uniform raw material;

[0034] 2) Calcination of raw materials after uniform mixing: The heating rate is 10℃ / min at 30-1350℃, the holding time at 900℃ is 60min, the heating rate is 5℃ / min at 900-1350℃, and the holding time at 1350℃ is 1h.

[0035] 3) Rapid cooling of clinker to form highly active minerals: Air cooling rate: not less than 150℃ / min for 1350-900℃, and not less than 70℃ / min for temperatures below 900℃;

[0036] 4) Grinding clinker minerals: The average particle size of the clinker minerals after grinding is 20μm, and the clinker powder is stored at a humidity of 30%; thus, modified iron mineral materials that improve the wear resistance and corrosion resistance of cement are obtained.

[0037] Example 2

[0038] 1) Mix 60 wt.% calcium carbonate, 20 wt.% aluminum oxide, and 20 wt.% iron oxide into a uniform raw material;

[0039] 2) Calcination of raw materials after uniform mixing: The heating rate is 10℃ / min at 30-1350℃, the holding time at 900℃ is 60min, the heating rate is 5℃ / min at 900-1350℃, and the holding time at 1350℃ is 1h.

[0040] 3) Rapid cooling of clinker to form highly active minerals: Air cooling rate: not less than 150℃ / min for 1350-900℃, and not less than 70℃ / min for temperatures below 900℃;

[0041] 4) Grinding clinker minerals: The average particle size of the clinker minerals after grinding is 20μm, and the clinker powder is stored at a humidity of 30%; thus, modified iron mineral materials that improve the wear resistance and corrosion resistance of cement are obtained.

[0042] Example 3

[0043] 1) Mix 58 wt.% calcium carbonate, 15 wt.% aluminum oxide, 25 wt.% iron oxide, and 2 wt.% calcium fluoride into a homogeneous raw material;

[0044] 2) After uniform mixing, the raw materials are calcined: the heating rate is 10℃ / min at 30-1250℃, the holding time at 900℃ is 60min, the heating rate at 900-1250℃ is 5℃ / min, and the holding time at the firing temperature (1250℃) is 1h.

[0045] 3) Rapid cooling of clinker to form highly active minerals: Air cooling rate: not less than 150℃ / min for 1250-900℃, and not less than 70℃ / min for temperatures below 900℃;

[0046] 4) Grinding clinker minerals: The average particle size of the clinker minerals after grinding is 20μm, and the clinker powder is stored at a humidity of 30%; thus, modified iron mineral materials that improve the wear resistance and corrosion resistance of cement are obtained.

[0047] Example 4

[0048] 1) Mix 55 wt.% calcium carbonate, 20 wt.% aluminum oxide, 20 wt.% iron oxide, and 5 wt.% calcium fluoride into a uniform raw material;

[0049] 2) After uniform mixing, the raw materials are calcined: the heating rate is 10℃ / min at 30-1250℃, the holding time at 900℃ is 60min, the heating rate at 900-1250℃ is 5℃ / min, and the holding time at the firing temperature (1250℃) is 1h.

[0050] 3) Rapid cooling of clinker to form highly active minerals: Air cooling rate: not less than 150℃ / min for 1250-900℃, and not less than 70℃ / min for temperatures below 900℃;

[0051] 4) Grinding clinker minerals: The average particle size of the clinker minerals after grinding is 20μm, and the clinker powder is stored at a humidity of 30%; thus, modified iron mineral materials that improve the wear resistance and corrosion resistance of cement are obtained.

[0052] Example 5

[0053] 1) Mix 55 wt.% calcium carbonate, 20 wt.% aluminum oxide, 20 wt.% iron oxide, and 5 wt.% calcium sulfate into a uniform raw material;

[0054] 2) Calcination of raw materials after uniform mixing: The heating rate is 10℃ / min at 30-1300℃, the holding time at 900℃ is 60min, the heating rate is 5℃ / min at 900-1300℃, and the holding time at the firing temperature (1300℃) is 1h.

[0055] 3) Rapid cooling of clinker to form highly active minerals: Air cooling rate: not less than 150℃ / min for 1300-900℃, and not less than 70℃ / min for temperatures below 900℃;

[0056] 4) Grinding clinker minerals: The average particle size of the clinker minerals after grinding is 20μm, and the clinker powder is stored at a humidity of 30%; thus, modified iron mineral materials that improve the wear resistance and corrosion resistance of cement are obtained.

[0057] Example 6

[0058] 1) Mix 60 wt.% calcium carbonate, 15 wt.% aluminum oxide, and 25 wt.% iron oxide into a homogeneous raw meal (low aluminum-iron ratio); or mix 60 wt.% calcium carbonate, 25 wt.% aluminum oxide, and 15 wt.% iron oxide into a homogeneous raw meal (high aluminum-iron ratio).

[0059] 2) Calcination of raw materials after uniform mixing: The heating rate is 10℃ / min at 30-1350℃, the holding time at 900℃ is 60min, the heating rate is 5℃ / min at 900-1350℃, and the holding time at 1350℃ is 1h.

[0060] 3) Rapid cooling of clinker to form highly active minerals: Air cooling rate: not less than 150℃ / min for 1350-900℃, and not less than 70℃ / min for temperatures below 900℃;

[0061] 4) Grinding clinker minerals: According to the ratio of high aluminum-iron ratio to low aluminum-iron ratio iron mineral materials of 3:5, iron mineral materials with the same aluminum-iron ratio as in Example 2 are obtained. The average particle size of the clinker minerals after grinding is 20μm, and the moisture content of the clinker powder is 30%. Modified iron mineral materials that improve the wear resistance and corrosion resistance of cement are obtained.

[0062] Performance testing

[0063] The modified iron mineral materials obtained in the above comparative examples and embodiments were used as admixtures in the preparation of concrete, and the performance was tested. The results are shown in Table 1 below. Wherein:

[0064] The control group used cement, sand, and water to prepare concrete, with a water-cement ratio of 0.5 and a sand-cement ratio of 3. P·I 42.5 cement and standard sand were selected.

[0065] The experimental group was based on the control group, with the modified iron mineral material obtained from the comparative and example examples used as an admixture to replace 10% of the cement mass fraction, according to a water-cement ratio of 0.5 and a sand-cement ratio of 3. P·I 42.5 cement and standard sand were selected.

[0066] Table 1. Performance test results of the modified iron mineral materials obtained in each embodiment and comparative example.

[0067]

[0068] The control group was tested without mineral modifiers; the compressive strength performance was tested according to standard GB / T17671-2021; the impact and abrasion performance was tested according to standard SL 352-2006, and the impact and abrasion resistance was measured according to the mass loss before and after impact and abrasion; the chloride ion adsorption performance was tested by the adsorption amount of 10g cement sample after hydration for 28 days in 100mL of NaCl solution (1mmol / L).

[0069] As shown in Table 1, compared with the control group, the mineral calcined at high temperature with 10% silica in Comparative Example 1 can improve chloride ion adsorption performance, but it reduces compressive strength and impact resistance. The compressive strength and impact resistance of the control group are not as good as those in Example 1. This is mainly because the silicate minerals in the low-temperature calcined minerals have low (or no) activity, resulting in a decrease in overall strength and poor impact resistance; indicating that not just any substance can be used as an activity regulator in the formulation of this invention.

[0070] In the silica-free examples (Examples 1-5), compared to the control group, the impact resistance and chloride ion adsorption performance were effectively improved simultaneously at 28d and 56d without strength reduction.

[0071] Compared with Example 1, Example 2 shows that the aluminum content in the admixture is increased and the iron content is decreased, which has a slight effect on improving the compressive strength, but weakens the chloride ion adsorption performance and wear resistance.

[0072] Compared with Example 1, Example 3 added calcium fluoride as an active regulator, which lowered the firing temperature and was beneficial to strength development, while improving chloride ion adsorption performance and wear resistance; this was also demonstrated in Example 4 compared with Example 2.

[0073] Compared with Example 1, Example 4 added calcium fluoride as an active regulator. The minerals calcined at low temperature, high aluminum and low iron content had strong chloride ion adsorption energy, and their anti-abrasion properties remained basically unchanged.

[0074] Compared with Example 3, Example 4 shows that, in the presence of the active regulator calcium fluoride, increasing the aluminum-iron ratio is beneficial to strength development, enhances chloride ion resistance, and slightly reduces impact and abrasion resistance.

[0075] Compared with Example 4, Example 5 shows that the mineral admixture calcined with calcium sulfate as the active regulator is more favorable for the 28-day strength development than calcium fluoride. However, the use of calcium fluoride shows better chloride ion adsorption performance and impact resistance.

[0076] Compared with Example 2, Example 6 shows that the composite iron mineral with high activity and low activity has better 28-day and 56-day strength than the iron mineral material with the same Al / Fe ratio calcined alone, and its resistance to chloride ions and abrasion is improved; this is attributed to the better stepwise hydration performance of the composite iron mineral material.

[0077] Compared with existing technologies, this invention discloses a modified ferrous mineral material and its preparation method for improving the wear resistance and corrosion resistance of cement. This admixture mainly produces a highly active, highly wear-resistant, and chloride-resistant modified ferrous mineral material for cement through calcination and rapid cooling of calcium, aluminum, iron, and an activity regulator. The process includes the following steps: preparing a uniformly mixed raw meal of 40-70 parts calcium carbonate, 5-30 parts alumina, 5-30 parts iron oxide, and 0-5 parts an activity regulator; calcining the uniformly mixed raw meal at 1100-1350℃ for 0.5-3 hours to obtain clinker; and rapidly cooling the clinker to obtain a highly active mineral. Rapid cooling is beneficial for increasing the glass content, increasing mineral activity, and improving early strength. Under the same calcination conditions, the faster the cooling rate, the higher the glass content. Calcination time affects mineral formation, thus affecting performance. Calcination times below 0.5 hours result in incomplete chemical reactions, producing a large amount of calcium oxide in the product, which reduces the performance of cement concrete.

[0078] The functional cement-modified ferrous mineral material of this invention increases the content of chloride ion curing agent in the cement system by increasing the aluminum content within a suitable range. This ensures high strength (28-day compressive strength of 49.6–53.0 MPa, 56-day compressive strength of 54.9–56.7 MPa) while improving chloride ion resistance (56-day chloride ion adsorption reaches 4.75–5.09 mg / g). Simultaneously, increasing the iron content in the system enhances the cement's abrasion resistance (56-day impact abrasion resistance of 2.8–3.7 g). The increase in cement system strength stems from the ferrous mineral reducing the cement's water demand, increasing the effective water / cement ratio, improving the cement's hydration degree, and the ferrous mineral itself contributing to strength development. The improved impact abrasion resistance mechanism arises from two factors: firstly, Al enters the cement hydration product calcium silicate hydrate (CSH), forming C-(A,S)-H, increasing the hardness of the hydration product; secondly, it stems from the high hardness value of the mineral admixture itself.

[0079] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A modified ferrous mineral material for improving the wear resistance and corrosion resistance of cement, characterized in that, By mass percentage, the raw material consists of 55-60% calcium, 15-20% aluminum, 20-25% iron, and 0-5% activity regulator. The calcium component is calcium carbonate, the aluminum component is aluminum oxide, and the iron component is iron oxide. The activity regulator is any combination of one or more of sulfates and fluorides; The modified iron mineral material is a mineral admixture; The preparation method of the modified iron mineral material includes the following steps: Take the raw materials in the specified proportions and mix them to form a uniform raw meal; Raw materials are calcined to obtain clinker; calcination is carried out at a firing temperature of 1100~1350 ℃ for 0.5~3 h; Rapid cooling of clinker transforms it into active minerals; The active mineral crushing process yields modified ferrous mineral materials that improve the wear resistance and corrosion resistance of cement.

2. The modified ferrous mineral material for improving the wear resistance and corrosion resistance of cement according to claim 1, characterized in that, A mass ratio of alumina to iron oxide is A, where 1 < A ≤ 6 to obtain a modified iron mineral material X with a high aluminum-iron ratio, and 0.2 ≤ A ≤ 1 to obtain a modified iron mineral material Y with a low aluminum-iron ratio; the modified iron mineral material includes materials X and Y compounded in any proportion.

3. The modified ferrous mineral material for improving the wear resistance and corrosion resistance of cement according to claim 1, characterized in that, The modified iron mineral material has an average particle size of less than 70 µm.

4. The modified ferrous mineral material for improving the wear resistance and corrosion resistance of cement according to claim 1, characterized in that, The sulfate is any combination of one or more of sodium sulfate, potassium sulfate, and calcium sulfate; the fluoride is calcium fluoride.

5. The modified ferrous mineral material for improving the wear resistance and corrosion resistance of cement according to claim 1, characterized in that, Before calcination, the temperature is increased from room temperature to 900℃ at a rate of 8-12℃ / min, and held at 900℃ for 40-80 minutes; then the temperature is increased to the firing temperature at a rate of 4-6℃ / min.

6. The modified ferrous mineral material for improving the wear resistance and corrosion resistance of cement according to claim 1, characterized in that, Rapid cooling includes air cooling, oil cooling, or liquid nitrogen cooling; among them, the cooling rate is 100~500 ℃ / min between the firing temperature and 900℃; and the cooling rate is not less than 70 ℃ / min below 900℃.

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