High-strength low-energy-consumption cement and preparation method thereof

Abstract

The invention relates to the technical field of cement, and discloses high-strength low-energy-consumption cement and a preparation method thereof.The high-strength low-energy-consumption cement is prepared from, by weight, 65-80 parts of cement clinker, 180-230 parts of quartz sand, 4-10 parts of waterborne epoxy resin, 0.5-1.2 parts of lignin water reducing agent and the like; the cement clinker comprises the following components in parts by weight: 80-90 parts of limestone, 1.6-6.6 parts of coal gasification ash, 2-5.8 parts of sandstone tailings and the like. The lignin water reducer contains a large amount of sulfonate groups, so that the fluidity of the concrete is remarkably improved under the condition that the water consumption is not increased, and the mechanical strength of the cement mortar is improved. The lignin water reducer contains a large amount of chemical imino groups and can be subjected to a curing reaction with the epoxy resin, the cohesion of the cement mortar is improved through the cementing effect of the epoxy resin, and the mechanical properties such as compression resistance and breaking strength are improved.

Description

Technical Field

[0001] This invention relates to the field of cement technology, specifically to a high-strength, low-energy cement and its preparation method. Background Technology

[0002] Cement can be prepared by high-temperature firing of raw materials such as limestone, clay, gypsum, and slag. It can be made into cement mortar, grouting materials, concrete, and other products, and is widely used in transportation, water conservancy and hydropower, marine engineering, and other fields. In order to improve the bonding properties, mechanical strength, and other properties of cement materials, high molecular polymers can be used to modify cement, such as epoxy resin, polyurethane, and styrene-butadiene latex.

[0003] Epoxy resin possesses excellent adhesion and resistance to high and low temperatures. When added to cementitious materials, it can improve their mechanical strength, freeze-thaw resistance, and waterproofing properties. Water-reducing agents are functional additives that can reduce the amount of mixing water, improve the fluidity of cement and concrete pastes, reduce slump, and enhance mechanical properties. Examples include lignin sulfonate water-reducing agents and polyacrylic acid water-reducing agents. Patent CN109320123B discloses a modified lignin sulfonate water-reducing agent prepared from sugarcane bagasse, chloroacetic acid, tea polyphenols, betaine, and sulfonating agents, which exhibits good compatibility with cement and stable storage performance. However, this water-reducing agent does not significantly improve the compressive and flexural strength of cement materials. Summary of the Invention

[0004] This invention solves the problem of low compressive and flexural mechanical properties of cement.

[0005] The technical solution of this invention: a high-strength, low-energy cement and its preparation method. (1) Add alkali lignin to an aqueous sodium hydroxide solution, stir and then add epichlorohydrin. Stir to react. At this time, the phenolic hydroxyl groups of alkali lignin react with epichlorohydrin. After filtration, wash with ethanol and dry the filter cake to obtain epoxy lignin.

[0006] (2) Add epoxy lignin and 2-aminoethanesulfonic acid to water, stir, and then add sodium hydroxide aqueous solution dropwise. Stir to react. At this time, the amino group of 2-aminoethanesulfonic acid reacts with the epoxy group of epoxy lignin. Heat to evaporate and precipitate the product. Cool in an ice-water bath, filter, and dry the precipitate to obtain lignin water-reducing agent. The reaction formula is: .

[0007] (3) After the limestone, coal gasification ash, sandstone tailings, desulfurized gypsum and iron tailings are mixed and homogenized, they are preheated in a preheater, then thermally decomposed in a decomposition furnace, and finally solid-phase reaction, calcination and cooling are carried out in a rotary kiln to obtain cement clinker.

[0008] (4) Add cement clinker, fly ash, quartz sand and lignin water-reducing agent to water, mix and blend, then add water-based epoxy resin, add to the mold, stir and mix, demold and cure to obtain high-strength low-energy cement.

[0009] Preferably, the mass fraction of sodium hydroxide aqueous solution in (1) is 15-22%.

[0010] Preferably, (1) the amount of alkali lignin is 100 parts by weight and the amount of epichlorohydrin is 800-1500 parts by weight.

[0011] Preferably, the reaction temperature in (1) is 70-85℃ and the reaction time is 3-5h.

[0012] Preferably, in (2), the amount of epoxy lignin is 100 parts by weight and the amount of 2-aminoethanesulfonic acid is 30-70 parts by weight.

[0013] Preferably, in (2), sodium hydroxide aqueous solution is added dropwise to adjust the pH to 10-11.

[0014] Preferably, the reaction temperature in (2) is 60-70℃ and the reaction time is 10-16h.

[0015] Preferably, the preheating temperature of the preheater in (3) is 720-760℃.

[0016] Preferably, the temperature of thermal decomposition in the decomposition furnace in (3) is 780-850°C.

[0017] Preferably, the temperature of the solid-phase reaction in (3) is 1150-1250℃ and the time is 6-10min.

[0018] Preferably, in (3), the firing temperature in the rotary kiln is 1300-1450℃ and the firing time is 4-7min.

[0019] Preferably, in (3), the amount of limestone is 80-90 parts by weight, the amount of coal gasification ash is 1.6-6.6 parts by weight, the amount of sandstone tailings is 2-5.8 parts by weight, the amount of desulfurized gypsum is 0.2-2.3 parts by weight, and the amount of iron tailings is 1.2-5.8 parts by weight.

[0020] Preferably, in (4), the amount of cement clinker is 65-80 parts by weight, fly ash is 20-35 parts by weight, quartz sand is 180-230 parts by weight, waterborne epoxy resin is 4-10 parts by weight, lignin water-reducing agent is 0.5-1.2 parts by weight, and water is 32-38 parts by weight.

[0021] Preferably, the temperature during curing in (4) is 20-25℃, the relative humidity is 90-95%, and the time is 3-30 days.

[0022] The beneficial technical effects of this invention are as follows: This invention uses industrial solid waste such as coal gasification ash, sandstone tailings, and iron tailings to replace some of the raw materials such as limestone used in cement production. This makes it easier to reduce the clinker firing temperature and energy consumption, thus solving resource and environmental pollution problems.

[0023] This invention utilizes epichlorohydrin and 2-aminoethanesulfonic acid to react sequentially with alkali lignin, obtaining a lignin water-reducing agent containing sulfonic acid groups and chemical imino groups. This agent is then compounded with cement clinker, water-based epoxy resin, and quartz sand to produce high-strength, low-energy-consumption cement mortar. The lignin water-reducing agent contains a large number of sulfonate groups, which can act on the surface of cement particles through physical and chemical adsorption such as van der Waals forces and ionic bonds. This causes the cement silicate particles to acquire a uniform negative charge, resulting in mutual repulsion between adjacent cement silicate particles. This reduces the agglomeration of cement particles and simultaneously disrupts the original flocculated structure, releasing trapped free water. Without increasing water consumption, this significantly improves the fluidity of concrete, thereby enhancing the mechanical strength of the cement mortar.

[0024] The lignin water-reducing agent of the present invention contains a large number of chemical imino groups, which can undergo a curing reaction with epoxy resin, so that the epoxy resin forms a continuous chemical cross-linking network inside the cement mortar. Through the cementing effect of epoxy resin, the cohesion of the cement mortar is improved, and the mechanical properties such as compressive strength and flexural strength are improved. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0026] Example 1: (1) Add 50g of alkali lignin to 300mL of sodium hydroxide aqueous solution with a mass fraction of 18%, stir, add 520g of epichlorohydrin, heat to 75℃, stir for 3h, filter, wash with ethanol, dry the filter cake to obtain epoxy lignin.

[0027] (2) Add 100g of epoxy lignin and 45g of 2-aminoethanesulfonic acid to 1.2L of water, stir, add sodium hydroxide aqueous solution to adjust the pH to 10, heat to 70℃, stir and react for 10h, heat to evaporate and precipitate the precipitate, cool in an ice water bath, filter, dry the precipitate to obtain lignin water-reducing agent.

[0028] (3) Mix 8.3 kg of limestone, 320 g of coal gasification ash, 580 g of sandstone tailings, 20 g of desulfurized gypsum and 430 g of iron tailings and homogenize them. Then put them into the preheater and preheat at 750 °C. Then put them into the decomposition furnace and thermally decompose at 780 °C. Finally put them into the rotary kiln and carry out solid-phase reaction at 1200 °C for 7 min and calcination at 1450 °C for 4 min. After cooling, cement clinker is obtained.

[0029] (4) Add 8kg of cement clinker, 2kg of fly ash, 21kg of quartz sand (standard sand, the same below) and 50g of lignin water-reducing agent to 3.8L of water, mix well, add 0.4kg of water-based epoxy resin (model Hansen 3522-W-60A, Hubei Langbowan Biomedical), add to the mold, stir and mix, demold, and cure at 20℃ and 95% relative humidity for 28 days to obtain high-strength low-energy cement.

[0030] Example 2: (1) Add 50g of alkali lignin to 300mL of sodium hydroxide aqueous solution with a mass fraction of 15%, stir, add 400g of epichlorohydrin, heat to 85℃, stir for 3h, filter, wash with ethanol, dry the filter cake to obtain epoxy lignin.

[0031] (2) Add 100g of epoxy lignin and 30g of 2-aminoethanesulfonic acid to 1.2L of water, stir, add sodium hydroxide aqueous solution to adjust the pH to 11, heat to 70℃, stir and react for 12h, heat to evaporate and precipitate, cool in ice water bath, filter, dry the precipitate to obtain lignin water-reducing agent.

[0032] (3) Mix 9kg limestone, 160g coal gasification ash, 240g sandstone tailings, 230g desulfurized gypsum and 120g iron tailings evenly and homogenize them before putting them into a preheater and preheating them at 720℃. Then put them into a decomposition furnace and thermally decompose them at 800℃. Finally put them into a rotary kiln and carry out solid-phase reaction at 1150℃ for 10min and calcination at 1400℃ for 4min. After cooling, cement clinker is obtained.

[0033] (4) Add 7.5kg of cement clinker, 2.5kg of fly ash, 23kg of quartz sand and 70g of lignin water-reducing agent to 3.6L of water, mix well and then add 0.6kg of water-based epoxy resin into the mold, stir and mix, demold, and cure at 20℃ and 95% relative humidity for 28 days to obtain high-strength low-energy cement.

[0034] Example 3: (1) Add 50g of alkali lignin to 250mL of sodium hydroxide aqueous solution with a mass fraction of 20%, stir, add 750g of epichlorohydrin, heat to 70℃, stir for 5h, filter, wash with ethanol, dry the filter cake to obtain epoxy lignin.

[0035] (2) Add 100g of epoxy lignin and 70g of 2-aminoethanesulfonic acid to 1.5L of water, stir, add sodium hydroxide aqueous solution to adjust the pH to 11, heat to 65℃, stir and react for 16h, heat to evaporate and precipitate, cool in ice water bath, filter, dry the precipitate to obtain lignin water-reducing agent.

[0036] (3) Mix 8.6 kg of limestone, 660 g of coal gasification ash, 200 g of sandstone tailings, 120 g of desulfurized gypsum and 290 g of iron tailings and homogenize them. Then put them into a preheater and preheat them at 720 °C. Then put them into a decomposition furnace and thermally decompose them at 850 °C. Finally put them into a rotary kiln and carry out solid-phase reaction at 1250 °C for 6 min and calcination at 1400 °C for 5 min. After cooling, cement clinker is obtained.

[0037] (4) Add 7kg of cement clinker, 3kg of fly ash, 18kg of quartz sand and 95g of lignin water-reducing agent to 3.5L of water, mix well and then add 0.8kg of water-based epoxy resin into the mold, stir and mix, demold, and cure at 20℃ and 95% relative humidity for 28 days to obtain high-strength and low-energy cement.

[0038] Example 4: (1) Add 50g of alkali lignin to 250mL of sodium hydroxide aqueous solution with a mass fraction of 22%, stir, add 630g of epichlorohydrin, heat to 80℃, stir for 5h, filter, wash with ethanol, dry the filter cake to obtain epoxy lignin.

[0039] (2) Add 100g of epoxy lignin and 58g of 2-aminoethanesulfonic acid to 1.4L of water, stir, add sodium hydroxide aqueous solution to adjust the pH to 11, heat to 60℃, stir and react for 16h, heat to evaporate and precipitate, cool in ice water bath, filter, dry the precipitate to obtain lignin water-reducing agent.

[0040] (3) Mix 8.5 kg of limestone, 410 g of coal gasification ash, 370 g of sandstone tailings, 170 g of desulfurized gypsum and 580 g of iron tailings and homogenize them. Then put them into a preheater and preheat them at 760 °C. Then put them into a decomposition furnace and thermally decompose them at 800 °C. Finally put them into a rotary kiln and carry out solid-phase reaction at 1200 °C for 10 min and calcination at 1300 °C for 7 min. After cooling, cement clinker is obtained.

[0041] (4) Add 6.5kg of cement clinker, 3.5kg of fly ash, 20kg of quartz sand and 120g of lignin water-reducing agent to 3.2L of water, mix well, add 1kg of water-based epoxy resin, add to the mold, stir and mix, demold, and cure at 20℃ and 95% relative humidity for 28 days to obtain high-strength low-energy cement.

[0042] Comparative Example 1: (1) Add 8 kg of cement clinker (prepared from Example 1), 2 kg of fly ash, and 21 kg of quartz sand to 3.8 L of water, mix well, add 0.4 kg of waterborne epoxy resin, add to the mold, stir and mix, demold, and cure at 20°C and 95% relative humidity for 28 days to obtain cement.

[0043] Comparative Example 2: (1) Add 8 kg of cement clinker (prepared from Example 1), 2 kg of fly ash, 21 kg of quartz sand and 50 g of alkali lignin to 3.8 L of water, mix well and then add 0.4 kg of water-based epoxy resin into the mold, stir and mix, demold, and cure at 20 °C and 95% relative humidity for 28 days to obtain cement.

[0044] Comparative Example 3: (1) Add 100g of epoxy lignin and 45g of n-propylene to 1.2L of water, stir, add sodium hydroxide solution to adjust the pH to 10, heat to 70℃, stir, reflux for 10h, heat to evaporate and precipitate, cool in an ice water bath, filter, dry the precipitate to obtain amination lignin.

[0045] (1) Add 8 kg of cement clinker (prepared from Example 1), 2 kg of fly ash, 21 kg of quartz sand and 50 g of aminated lignin to 3.8 L of water, mix well and then add 0.4 kg of waterborne epoxy resin into the mold, stir and mix, demold, and cure at 20 °C and 95% relative humidity for 28 days to obtain cement.

[0046] Comparative Example 4: (1) Add 8 kg of cement clinker (prepared from Example 1), 2 kg of fly ash, 21 kg of quartz sand, and 50 g of lignin water-reducing agent (calcium lignin sulfonate, effective ingredient content 99%, Jinan Zhiheng Zhiyuan Chemical Technology) to 3.8 L of water. After mixing, add 0.4 kg of water-based epoxy resin, add it to the mold, stir and mix, demold, and cure at 20℃ and 95% relative humidity for 28 days to obtain cement.

[0047] Comparative Example 5: (1) Add 8 kg of cement clinker (prepared from Example 1), 2 kg of fly ash, 21 kg of quartz sand, and 50 g of amine curing agent (model 593 aliphatic modified amine, Guangzhou Qihua Chemical) to 3.8 L of water. After mixing, add 0.4 kg of waterborne epoxy resin, add it to the mold, stir and mix, demold, and cure at 20 °C and 95% relative humidity for 28 days to obtain cement.

[0048] The compressive strength and flexural strength of cement were tested according to the method of GB / T 17671-2021.

[0049] Table 1. Properties of Cement The cement mortars in Examples 1-4 exhibit higher compressive and flexural strengths, primarily due to the addition of lignin water-reducing agents and epoxy resin binders. The lignin water-reducing agent contains a large number of sulfonate groups, which can act on the surface of cement particles through physical and chemical adsorption via van der Waals forces and ionic bonds. This causes the cement silicate particles to acquire a uniform negative charge, resulting in mutual repulsion between adjacent particles, thus reducing particle agglomeration. Simultaneously, it disrupts the original flocculated structure, releasing trapped free water and significantly improving concrete fluidity without increasing water consumption, thereby enhancing the mechanical strength of the cement mortar. Furthermore, the lignin water-reducing agent contains a large number of chemical imino groups, which can undergo a curing reaction with epoxy resin, forming a continuous chemical cross-linking network within the cement mortar. Through the binding effect of the epoxy resin, the cohesion of the cement mortar is increased, further improving mechanical properties such as compressive and flexural strength.

[0050] Compared with Example 1, Comparative Example 1 did not add lignin water-reducing agent, which is not conducive to improving the strength of cement mortar, and the added epoxy resin cannot undergo curing reaction, which seriously affects the compressive and flexural strength.

[0051] The alkali lignin added in Comparative Example 2 does not contain sulfonate groups, making it difficult for the water-reducing agent to work effectively. Furthermore, it does not contain imino groups, so it cannot undergo a curing reaction with epoxy resin. Consequently, the compressive and flexural strengths of the cement mortar are lower than those in Example 1.

[0052] The aminated lignin in Comparative Example 3 does not contain sulfonate groups, making it difficult to act as a water-reducing agent. The compressive and flexural strengths of the cement mortar are lower than those in Example 1.

[0053] Comparative Example 4 added a commercially available lignin water-reducing agent, which does not contain active imino groups and is difficult to cure with epoxy resin. The compressive and flexural strengths of the cement mortar were lower than those in Example 1.

[0054] Comparative Example 5 added a commercially available amine curing agent, but did not add a water-reducing agent. The compressive and flexural strengths of the cement mortar were lower than those of Example 1.

[0055] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-strength, low-energy-consumption cement, characterized in that, The high-strength, low-energy cement comprises 65-80 parts by weight of cement clinker, 20-35 parts by weight of fly ash, 180-230 parts by weight of quartz sand, 4-10 parts by weight of water-based epoxy resin, 0.5-1.2 parts by weight of lignin water-reducing agent, and 32-38 parts by weight of water. The cement clinker comprises 80-90 parts by weight of limestone, 1.6-6.6 parts by weight of coal gasification ash, 2-5.8 parts by weight of sandstone tailings, 0.2-2.3 parts by weight of desulfurized gypsum, and 1.2-5.8 parts by weight of iron tailings.

2. The high-strength, low-energy-consumption cement according to claim 1, characterized in that, The preparation method of the lignin water-reducing agent is as follows: (1) Add alkali lignin to an aqueous sodium hydroxide solution, stir, add epichlorohydrin, stir to react, filter and wash, dry the filter cake to obtain epoxy lignin; (2) Add epoxy lignin and 2-aminoethanesulfonic acid to water, stir, add sodium hydroxide solution dropwise, stir to react, heat to evaporate, cool in an ice water bath, filter, dry the precipitate to obtain lignin water-reducing agent.

3. The high-strength, low-energy-consumption cement according to claim 2, characterized in that, The mass fraction of the sodium hydroxide aqueous solution in (1) is 15-22%.

4. The high-strength, low-energy-consumption cement according to claim 2, characterized in that, The amount of alkali lignin used in (1) is 100 parts by weight, and the amount of epichlorohydrin is 800-1500 parts by weight.

5. The high-strength, low-energy-consumption cement according to claim 2, characterized in that, The reaction temperature in (1) is 70-85℃ and the reaction time is 3-5h.

6. The high-strength, low-energy-consumption cement according to claim 2, characterized in that, In (2), the amount of epoxy lignin is 100 parts by weight and the amount of 2-aminoethanesulfonic acid is 30-70 parts by weight.

7. The high-strength, low-energy-consumption cement according to claim 2, characterized in that, In step (2), sodium hydroxide aqueous solution is added dropwise to adjust the pH to 10-11.

8. The high-strength, low-energy-consumption cement according to claim 2, characterized in that, The reaction temperature in (2) is 60-70℃ and the reaction time is 10-16h.

9. The high-strength, low-energy-consumption cement according to claim 1, characterized in that, The method for preparing cement clinker includes: mixing and homogenizing limestone, coal gasification ash, sandstone tailings, desulfurized gypsum, and iron tailings, then feeding them into a preheater, preheating them, and then feeding them into a decomposition furnace for thermal decomposition. Finally, the mixture is fed into a rotary kiln for solid-phase reaction, calcination, and cooling to obtain cement clinker.

10. A method for preparing high-strength, low-energy-consumption cement as described in any one of claims 1-9, characterized in that, The preparation method includes: adding cement clinker, fly ash, quartz sand, and lignin water-reducing agent to water, mixing and blending them, adding water-based epoxy resin, adding the mixture to a mold, stirring and mixing, demolding, and curing to obtain high-strength, low-energy cement.

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