Nanometer reinforced internal curing sulfate-resistant cave residue concrete and preparation method thereof

Abstract

The application provides a kind of nano-reinforced internal curing anti-sulfate cave slag concrete and its preparation method, relating to the technical field of building materials, according to weight parts, the raw materials of the concrete include: Portland cement 100-500 parts, cave slag stone powder 30-300 parts, fine aggregate 1000-1500 parts, nano Fe2O3 1-5 parts, water-absorbing resin 0.5-2 parts, barium hydroxide 3-5 parts and water 200-300 parts.The nano-reinforced internal curing anti-sulfate cave slag concrete provided by the application realizes the replacement of cement by cave slag stone powder, can effectively reduce CO2 emission, has good mechanical properties and working performance, excellent anti-sulfate erosion performance and other characteristics, improves the service performance of concrete structure, greatly improves the service life of building, and is especially suitable for bridge engineering and other engineering construction with high requirements for building life.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a nano-reinforced internally cured sulfate-resistant caving concrete and its preparation method. Background Technology

[0002] With the increasing awareness of sustainable development strategies in the construction industry, reducing CO2 emissions related to the construction sector is imperative. Portland Cement produces an average of 4 billion tons annually, accounting for 8-10% of global anthropogenic CO2 emissions. Replacing cement with travertine powder can effectively reduce CO2 emissions. Furthermore, travertine powder has filling, nucleation, and dilution properties, improving the density of the matrix. Replacing cement with travertine powder and river sand with manufactured sand represents a mainstream trend in the green development of engineering materials.

[0003] However, the incorporation of travertine powder weakens the resistance of cementitious materials to sulfate attack. Travertine powder reacts with the aluminum phase in the matrix, hindering the transformation of ettringite into monosulfide-type hydrated calcium sulfoaluminate. In cementitious materials containing travertine powder, gypsum becomes the main erosion product, and its formation occurs before that of ettringite. Furthermore, cementitious materials containing travertine powder are more prone to carbon-sulfur-silica-calcium-lithium type damage. How to fully utilize travertine powder while ensuring the sulfate resistance of concrete is a pressing issue that needs to be addressed.

[0004] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide a nano-reinforced, internally cured, sulfate-resistant tunnel slag concrete, so as to realize the effective utilization of tunnel slag powder and solve the problem that concrete is not resistant to sulfate erosion after incorporating tunnel slag powder.

[0006] The present invention also aims to provide a method for preparing the above-mentioned nano-reinforced internally cured sulfate-resistant slag concrete.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A nano-reinforced, internally cured, sulfate-resistant cave slag concrete comprises, by weight, the following components: 100-500 parts silicate cement, 30-300 parts cave slag powder, 1000-1500 parts fine aggregate, 1-5 parts nano Fe2O3, 0.5-2 parts water-absorbing resin, 3-5 parts barium hydroxide, and 200-300 parts water.

[0009] Preferably, the silicate cement is ordinary silicate cement with a strength grade of not less than 42.5, and the fine aggregate is manufactured sand.

[0010] Preferably, the quarry slag is composed of dolomite with a specific surface area ≥ 500 m². 2 / kg, CaCO3 content ≥85%.

[0011] Preferably, the manufactured sand is crushed cave debris sand, with dolomite as the lithology and a particle size ≤ 5mm.

[0012] Preferably, the nano-Fe2O3 particles have a size of 10–100 nm and a purity of ≥99%.

[0013] Preferably, the absorbent resin has a particle size of 50-150 mesh.

[0014] Preferably, the barium hydroxide is a monohydrate with a purity of ≥98%.

[0015] Preferably, the water is tap water.

[0016] This invention also provides a method for preparing any of the above-mentioned nano-reinforced internally cured sulfate-resistant slag concrete, comprising the following steps:

[0017] S1. After fully dissolving barium hydroxide in an aqueous solution, add the water-absorbing resin to the barium hydroxide solution and disperse it fully to obtain a water-absorbing resin-barium hydroxide dispersion.

[0018] S2. Weigh out silicate cement, slag powder, water-absorbing resin-barium hydroxide dispersion, nano Fe2O3, and fine aggregate according to the proportions, pour them into a concrete mixer and dry mix, then add water and mix again to obtain nano-reinforced internal curing sulfate-resistant slag concrete.

[0019] Preferably, in step S1, a magnetic stirrer or a paddle stirrer is used for stirring; in step S2, dry mixing is performed for 1 to 2 minutes, followed by adding water and stirring for 2 to 4 minutes.

[0020] Beneficial effects:

[0021] (1) This invention uses quarry stone powder as a powder material, utilizing its filling, nucleation, and dilution effects, as well as the filling and pozzolanic effects of nano-Fe2O3, the internal curing effect of water-absorbing resin, and the chemical effect of barium hydroxide, to influence the hydration products of cement-based materials, increase the phase volume, thereby reducing the porosity of cement-based materials, improving pore size distribution, and increasing the overall density of cement-based materials. This can improve the strength of cement-based materials, reduce volume shrinkage, improve the later-stage strength and durability of concrete, and effectively inhibit SO2. 4 2- Migration of harmful ions in capillaries improves the sulfate resistance of concrete.

[0022] (2) The nano-reinforced internal curing sulfate-resistant slag concrete provided by the present invention has good workability and volume stability. The manufactured sand is evenly distributed in the slurry and has high robust self-compacting properties. It has excellent mechanical properties and durability. When applied to bridge engineering, it can provide a guarantee for the service life of the building. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0024] The present invention will now be described in detail with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0025] This invention addresses the problem of weak sulfate resistance in current tunnel slag concrete by providing a nano-reinforced, internally cured, sulfate-resistant tunnel slag concrete. By weight, it comprises the following components: 100-500 parts of silicate cement (e.g., 110, 150, 200, 250, 300, 350, 400, 450, 490 parts), 30-300 parts of tunnel slag powder (e.g., 40, 70, 100, 130, 160, 190, 200, 230, 260, 290 parts), and 1000-1500 parts of fine aggregate (e.g., 1010, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 14...). 0.00 parts, 1450 parts, 1490 parts), 1-5 parts of nano Fe2O3 (e.g., 1.1 parts, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4.0 parts, 4.5 parts, 4.9 parts), 0.5-2 parts of water-absorbing resin (e.g., 0.6 parts, 0.8 parts, 1.0 parts, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 1.9 parts), 3-5 parts of barium hydroxide (e.g., 3.1 parts, 3.3 parts, 3.5 parts, 3.7 parts, 3.9 parts, 4.0 parts, 4.1 parts, 4.3 parts, 4.5 parts, 4.7 parts, 4.9 parts), and 200-300 parts of water (210 parts, 220 parts, 230 parts, 240 parts, 250 parts, 260 parts, 270 parts, 280 parts, 290 parts).

[0026] In a preferred embodiment of the present invention, the silicate cement is ordinary silicate cement with a strength grade of not less than 42.5, and the fine aggregate is manufactured sand.

[0027] In a preferred embodiment of the present invention, the quarry slag powder is composed of dolomite with a specific surface area ≥ 500 m².2 / kg (e.g., 500m) 2 / kg, 510m 2 / kg, 550m 2 / kg), CaCO3 content ≥85% (e.g., 85%, 86%, 89%).

[0028] In a preferred embodiment of the present invention, the manufactured sand is crushed cave debris sand, the lithology is dolomite, and the particle size is ≤5mm (e.g., 0.1mm, 0.5mm, 1mm, 2mm, 3mm, 5mm).

[0029] In a preferred embodiment of the present invention, the nano Fe2O3 particles have a particle size of 10-100 nm (e.g., 11 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 99 nm) and a purity of ≥99% (e.g., 99%, 99.1%, 99.9%, 99.99%).

[0030] In a preferred embodiment of the present invention, the particle size of the water-absorbing resin is 50-150 mesh (e.g., 51 mesh, 60 mesh, 70 mesh, 80 mesh, 90 mesh, 100 mesh, 110 mesh, 120 mesh, 130 mesh, 140 mesh, 149 mesh).

[0031] In a preferred embodiment of the present invention, barium hydroxide is a monohydrate with a purity ≥98% (e.g., 98%, 98.1%, 98.5%, 99.0%, 99.5%, 99.9%, 99.99%), or anhydrous barium hydroxide may be used instead.

[0032] In a preferred embodiment of the present invention, the water is tap water.

[0033] This invention also provides a method for preparing any of the above-mentioned nano-reinforced internally cured sulfate-resistant slag concrete, comprising the following steps:

[0034] S1. After fully dissolving barium hydroxide in an aqueous solution, add the water-absorbing resin to the barium hydroxide solution and disperse it fully to obtain a water-absorbing resin-barium hydroxide dispersion.

[0035] S2. Weigh out silicate cement, slag powder, water-absorbing resin-barium hydroxide dispersion, nano Fe2O3, and fine aggregate according to the proportions, pour them into a concrete mixer and dry mix, then add water and mix again to obtain nano-reinforced internal curing sulfate-resistant slag concrete.

[0036] In a preferred embodiment of the present invention, in step S1, a magnetic stirrer or a paddle stirrer is used for stirring; in step S2, dry stirring is performed for 1 to 2 minutes (e.g., 1.1 min, 1.2 min, 1.3 min, 1.4 min, 1.5 min, 1.6 min, 1.7 min, 1.8 min, 1.9 min), followed by adding water and stirring for 2 to 4 minutes (e.g., 2.1 min, 2.3 min, 2.5 min, 2.7 min, 2.9 min, 3.0 min, 3.1 min, 3.3 min, 3.5 min, 3.7 min, 3.9 min).

[0037] The present invention provides a detailed description of a nano-reinforced, internally cured, sulfate-resistant tunnel slag concrete and its preparation method through specific embodiments.

[0038] In the following examples and comparative examples:

[0039] The silicate cement used was ordinary silicate cement with a strength grade of 42.5. The quarry slag was composed of dolomite with a specific surface area of ​​500 m². 2 / kg, CaCO3 content ≥85%, fine aggregate is crushed sand from cave debris, lithology is dolomite, particle size ≤5mm; water-absorbing resin is purchased from Zhejiang Ningbo Formosa Plastics Water-absorbing Resin Co., Ltd., particle size is 50-150 mesh; barium hydroxide is purchased from Shanghai Maclean Biochemical Technology Co., Ltd., purity ≥98%.

[0040] Example 1

[0041] A nano-reinforced, internally cured, sulfate-resistant cave slag concrete is made from the following raw materials in parts by weight: 405 kg of ordinary silicate cement, 45 kg of cave slag powder, 1200 kg of crushed cave slag sand, 250 kg of water, 3 kg of nano Fe2O3, 0.8 kg of water-absorbing resin, and 5 kg of barium hydroxide.

[0042] The preparation method is as follows:

[0043] S1. After fully dissolving barium hydroxide in an aqueous solution using a magnetic stirrer, add the water-absorbing resin to the barium hydroxide solution and continue stirring to fully disperse it, thus obtaining a water-absorbing resin-barium hydroxide dispersion.

[0044] S2. Weigh out silicate cement, slag powder, water-absorbing resin-barium hydroxide dispersion, nano Fe2O3, and fine aggregate according to the proportion, pour them into a concrete mixer and dry mix for 1 minute, then add water and mix for 2 minutes to obtain nano-reinforced internal curing sulfate-resistant slag concrete.

[0045] Example 2

[0046] A nano-reinforced, internally cured, sulfate-resistant cave slag concrete is made from the following raw materials in parts by weight: 360 kg of ordinary silicate cement, 90 kg of cave slag powder, 1200 kg of crushed cave slag sand, 250 kg of water, 3 kg of nano Fe2O3, 0.8 kg of water-absorbing resin, and 5 kg of barium hydroxide.

[0047] The method for preparing nano-reinforced internally cured sulfate-resistant tunnel slag concrete provided in this embodiment is the same as in Embodiment 1.

[0048] Example 3

[0049] A nano-reinforced, internally cured, sulfate-resistant cave slag concrete is made from the following raw materials in parts by weight: 315 kg of ordinary silicate cement, 135 kg of cave slag powder, 1200 kg of crushed cave slag sand, 250 kg of water, 3 kg of nano Fe2O3, 0.8 kg of water-absorbing resin, and 5 kg of barium hydroxide.

[0050] The method for preparing nano-reinforced internally cured sulfate-resistant tunnel slag concrete provided in this embodiment is the same as in Embodiment 1.

[0051] Example 4

[0052] A nano-reinforced, internally cured, sulfate-resistant cave slag concrete is made from the following raw materials in parts by weight: 270 kg of ordinary silicate cement, 180 kg of cave slag powder, 1200 kg of crushed cave slag sand, 250 kg of water, 3 kg of nano Fe2O3, 0.8 kg of water-absorbing resin, and 5 kg of barium hydroxide.

[0053] The method for preparing nano-reinforced internally cured sulfate-resistant tunnel slag concrete provided in this embodiment is the same as in Embodiment 1.

[0054] Example 5

[0055] A nano-reinforced, internally cured, sulfate-resistant cave slag concrete is made from the following raw materials in parts by weight: 225 kg of ordinary silicate cement, 225 kg of cave slag powder, 1200 kg of crushed cave slag sand, 250 kg of water, 3 kg of nano Fe2O3, 0.8 kg of water-absorbing resin, and 5 kg of barium hydroxide.

[0056] The method for preparing nano-reinforced internally cured sulfate-resistant tunnel slag concrete provided in this embodiment is the same as in Embodiment 1.

[0057] Comparative Example 1

[0058] A type of concrete, which differs from Example 1 in that the slag powder is replaced with an equal mass of cement, and no nano Fe2O3, water-absorbing resin and barium hydroxide are added. The preparation method is the same as step S2 in Example 1.

[0059] Comparative Example 2

[0060] A type of slag concrete is made from raw materials comprising the following parts by weight: 225 kg of ordinary silicate cement, 225 kg of slag powder, 1200 kg of fine aggregate, and 250 kg of water, and its preparation method is the same as that of Comparative Example 1.

[0061] Comparative Example 3

[0062] A nano-reinforced caving muck concrete is made from the following raw materials in parts by weight: 225 kg of ordinary silicate cement, 225 kg of caving muck powder, 1200 kg of crushed caving muck sand, 250 kg of water, and 3 kg of nano-Fe2O3.

[0063] The method for preparing nano-reinforced internally cured sulfate-resistant tunnel slag concrete provided in this comparative example is the same as that in Comparative Example 1.

[0064] Comparative Example 4

[0065] An internally cured sulfate-resistant cave slag concrete is made from the following raw materials in parts by weight: 225 kg of ordinary silicate cement, 225 kg of cave slag powder, 1200 kg of crushed cave slag sand, 250 kg of water, 0.8 kg of water-absorbing resin, and 5 kg of barium hydroxide.

[0066] The method for preparing nano-reinforced internally cured sulfate-resistant tunnel slag concrete provided in this comparative example is the same as in Example 1.

[0067] Comparative Example 5

[0068] A type of slag concrete, which differs from Example 1 in that it does not contain nano Fe2O3, water-absorbing resin, or barium hydroxide, and is prepared using the same method as Comparative Example 1.

[0069] Performance evaluation:

[0070] 1. Concrete strength testing:

[0071] The 28-day compressive strength and flexural strength of the concrete prepared in Examples 1-5 and Comparative Examples 1-5 were tested according to GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete". During the test, the load should be applied continuously and uniformly at a rate of 0.5–0.8 MPa / s. When the specimen approached failure and began to deform rapidly, the throttle of the testing machine was stopped and adjusted until failure occurred. The failure load was then recorded in Table 1.

[0072] 2. Sulfate resistance test:

[0073] The sulfate resistance coefficients of the concrete samples prepared in Examples 1-5 and Comparative Examples 1-4 were tested. The erosion environment temperature was 20℃±3℃, the sulfate concentration was 15% (mass fraction), and the erosion age was 28 days. The sulfate resistance coefficients of the concrete samples were calculated.

[0074] The sulfate resistance coefficient is calculated as follows: the ratio of the flexural strength of a concrete sample after immersing it in a 15% sodium sulfate solution for 28 days to the flexural strength of a concrete sample of the same age immersed in clean drinking water is the sulfate resistance coefficient.

[0075] Table 1 Compressive strength and sulfate attack resistance coefficient of different concrete types

[0076] sample 28-day compressive strength (MPa) 28-day flexural strength (MPa) Sulfate erosion resistance coefficient Example 1 55.2 9.8 0.94 Example 2 50.9 8.5 0.87 Example 3 45.2 7.9 0.82 Example 4 40.9 6.9 0.79 Example 5 34.8 6.4 0.73 Comparative Example 1 53.6 9.1 0.88 Comparative Example 2 29.0 5.8 0.55 Comparative Example 3 40.6 7.0 0.66 Comparative Example 4 28.3 5.7 0.61 Comparative Example 5 53.4 8.9 Untested

[0077] As shown in Table 1, with constant additions of nano-Fe2O3, water-absorbing resin, and barium hydroxide, the 28-day compressive strength and 28-day flexural strength of the concrete samples gradually decreased with increasing incorporation of slag powder. The mechanical properties and sulfate resistance of the concrete also gradually declined, but good mechanical properties and sulfate resistance were still maintained. Meanwhile, as seen in Example 5 and Comparative Example 2, adding a certain proportion of slag powder, along with nano-Fe2O3, water-absorbing resin, and barium hydroxide, can improve the mechanical properties and sulfate resistance of the concrete. This demonstrates that the pozzolanic effect of nano-Fe2O3, the internal curing effect of water-absorbing resin, and the chemical effect of barium hydroxide can effectively activate the cement and slag powder. The filling of nanoparticles and hydration products increases the matrix density, thereby significantly improving the sulfate resistance of the concrete.

[0078] Comparative studies of Examples 1-5 and Comparative Example 1 revealed that the concrete prepared by incorporating a small amount of slag powder, along with a certain amount of nano-Fe2O3, water-absorbing resin, and barium hydroxide, exhibited superior mechanical properties and sulfate resistance compared to the concrete prepared without slag powder, nano-Fe2O3, water-absorbing resin, and barium hydroxide. The interaction between slag powder and nano-Fe2O3, water-absorbing resin, and barium hydroxide resulted in improved mechanical properties and sulfate resistance of the concrete.

[0079] Comparative Examples 2 and 4 show that the addition of water-absorbing resin and barium hydroxide leads to a decrease in the mechanical properties of concrete, but an increase in its resistance to sulfate attack. Furthermore, the applicant found in the experiments that if the amount of water-absorbing resin added was further increased compared to Comparative Example 4, the 28-day compressive strength and flexural strength of the concrete both decreased significantly, and the corrosion resistance coefficient also decreased markedly. Clearly, adding water-absorbing resin alone does not help improve the sulfate attack resistance of concrete.

[0080] In summary:

[0081] This invention uses a water-absorbing resin as an internal curing material and modifies it with barium hydroxide, enabling it to release barium ions in the later stages of erosion to react with invading sulfate ions to form BaSO4, thus reducing the formation of erosion products. Nano-Fe2O3 promotes cement hydration, forming a three-dimensional network structure within the cement paste, making the paste structure more compact. It also reacts with ettringite to form an iron-ettringite phase. The reduction in ettringite decreases the probability of carbon-sulfur-silica-calcium-type erosion, effectively hindering SO42-. 4 2- The migration of harmful ions in the capillaries improves the mechanical properties and resistance to sulfate attack of the structure.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A nano-reinforced, internally cured, sulfate-resistant caving concrete, characterized in that, The product comprises the following components by weight: 100-500 parts silicate cement, 30-300 parts quarry stone powder, 1000-1500 parts fine aggregate, 1-5 parts nano Fe2O3, 0.5-2 parts water-absorbing resin, 3-5 parts barium hydroxide, and 200-300 parts water. After fully dissolving barium hydroxide in an aqueous solution, the water-absorbing resin is added to the barium hydroxide solution and fully dispersed to obtain a water-absorbing resin-barium hydroxide dispersion.

2. The nano-reinforced, internally cured, sulfate-resistant caving concrete according to claim 1, characterized in that, The silicate cement is ordinary silicate cement with a strength grade of not less than 42.5, and the fine aggregate is manufactured sand.

3. The nano-reinforced, internally cured, sulfate-resistant caving concrete according to claim 1, characterized in that, The quarry slag is composed of dolomite with a specific surface area ≥ 500 m². 2 / kg, CaCO3 content ≥85%.

4. The nano-reinforced, internally cured, sulfate-resistant caving concrete according to claim 2, characterized in that, The manufactured sand is crushed cave debris sand, with a lithology of dolomite and a particle size ≤5mm.

5. The nano-reinforced, internally cured, sulfate-resistant caving concrete according to claim 1, characterized in that, The nano-Fe2O3 particles have a size of 10~100nm and a purity of ≥99%.

6. The nano-reinforced, internally cured, sulfate-resistant caving concrete according to claim 1, characterized in that, The absorbent resin has a particle size of 50-150 mesh.

7. The nano-reinforced, internally cured, sulfate-resistant caving concrete according to claim 1, characterized in that, The barium hydroxide is a monohydrate with a purity of ≥98%.

8. The nano-reinforced, internally cured, sulfate-resistant caving concrete according to claim 1, characterized in that, The water in question is tap water.

9. A method for preparing a nano-reinforced, internally cured, sulfate-resistant slag concrete according to any one of claims 1-8, characterized in that, Includes the following steps: S1. After fully dissolving barium hydroxide in an aqueous solution, add the water-absorbing resin to the barium hydroxide solution and disperse it fully to obtain a water-absorbing resin-barium hydroxide dispersion. S2. Weigh out silicate cement, slag powder, water-absorbing resin-barium hydroxide dispersion, nano Fe2O3, and fine aggregate according to the proportions, pour them into a concrete mixer and dry mix, then add water and mix again to obtain nano-reinforced internal curing sulfate-resistant slag concrete.

10. The method for preparing a nano-reinforced, internally cured, sulfate-resistant slag concrete according to claim 9, characterized in that, In step S1, a magnetic stirrer or a paddle stirrer is used for stirring; in step S2, dry stir for 1-2 minutes, then add water and stir for 2-4 minutes.