Improved preparation method of super-strong cement-based inorganic cementing material

Abstract

The invention provides an improved preparation method of a super-strong cement-based inorganic cementing material. The improved preparation method comprises the following steps: step 1, carrying out superfine mixing on Portland cement, silica fume and fly ash to obtain a super-strong cement base material; 2, coating the mixed material, adding mineral fibers in a grading manner, and continuously stirring and mixing; and step 3, firstly adding the superfine limestone powder and the superfine steel slag powder, then adding the efficient water reducing agent and the rheological agent, in addition, simultaneously adding the boric oxide modifier, and uniformly mixing. Based on the problem that the performance of an existing super-strong cement-based cementing material is reduced after being used for a period of time in an environment with high chloride ion content, the stability of the performance is kept by adding mineral fibers because the mineral fibers play a role in framework connection and play a role in hooking and fusing the cement-based cementing material, so that the performance of the cement-based cementing material is improved, and the service life of the cement-based cementing material is prolonged. The elasticity modulus and the pressure resistance are improved, and the quality of the inorganic cementing material is improved.

Description

Technical Field

[0001] The present invention relates to the modification of inorganic cementitious materials, and specifically to the modification technology of materials based on super-strong cement types. Background Art

[0002] Super-strong cement (usually referred to as high-performance cement or ultra-high-strength cement) is a very important inorganic cementitious material. It is a type of cement designed to obtain very high strength and durability characteristics. Super-strong cement not only has high compressive strength but also usually has very high impermeability, frost resistance, and chemical corrosion resistance. In some applications, it can withstand instantaneous and continuous loading. Cement, as an important inorganic cementitious material, is mainly used in building and infrastructure projects.

[0003] The characteristics of super-strong cement are generally as follows: High strength: The compressive strength of super-strong cement can usually reach above 80 MPa, and can even reach 100 MPa or higher, suitable for structures that bear large loads. Low water-binder ratio: Usually, a lower water-binder ratio (w / c) is adopted to improve the compactness and strength of concrete. Excellent durability: Super-strong cement often has very high impermeability and erosion resistance, suitable for projects in harsh environments. Good workability: The use of high-performance water-reducing agents and rheology modifiers can improve the fluidity of concrete, making it easier to operate during construction.

[0004] However, for existing super-strong cement materials, in some extreme cases, these concretes may have problems of cracking. Especially in environments with high chloride ion content, the application of super-strong cement (or high-performance cement) needs to be particularly cautious because chloride ions can affect the durability and strengthening structure of concrete. Chloride ions can cause corrosion of steel bars in concrete, shortening the service life and safety of the structure. Environments with high chloride ions may accelerate the deterioration process of concrete, affecting its strength and durability, and thus affecting the safety and service life of the structure. Summary of the Invention

[0005] To solve the problems existing in the above technologies, the present invention provides a mineral fiber-based modifier to solve this problem, thereby improving the characteristics of this super-strong cement-based cementitious material and obtaining better applications.

[0006] The present invention provides a method for modifying and preparing an inorganic cementitious material based on super-strong cement, which includes the following steps:

[0007] Step 1: Portland cement, silica fume, and fly ash are superfine-mixed to obtain a super-strong cement base material;

[0008] Step 2: The mixed materials are coated, mineral fibers are added in stages and continuously stirred and mixed; in addition, a boron oxide modifier is added simultaneously and uniformly mixed;

[0009] Step 3: First add ultrafine limestone powder and ultrafine steel slag powder, then add high-range water reducer and rheology modifier. Additionally, add boron oxide modifier simultaneously and mix evenly.

[0010] Preferably, the dosage ratio of mineral fiber to super-strong cement base material is 1:100 to 0.1:100.

[0011] Preferably, after the first classification and modification in Step 2, it is carried out in a new type of mixer and modifier.

[0012] Preferably, the dosage components are: 100 parts of portland cement, 10 parts of silica fume, 20 parts of fly ash, and 1 to 5 parts of high-range water reducer and rheology modifier. Further, 10 parts of ultrafine limestone powder and 10 parts of ultrafine steel slag powder. This ratio can also be: 100 parts of portland cement, 10 to 20 parts of silica fume, 10 to 20 parts of fly ash, and 0.5 to 5 parts of high-range water reducer and rheology modifier. Further, 10 to 20 parts of ultrafine limestone powder and 10 to 20 parts of ultrafine steel slag powder

[0013] Preferably, boron oxide is 5% to 20% of the dosage ratio of mineral fiber.

[0014] Preferably, the water reducer is sulfonate-based or lignosulfonate-based or polycarboxylate-based water reducer.

[0015] Preferably, the inorganic cementitious material of super-strong cement base obtained by the improved preparation method is mixed with aggregate and water to form a concrete structure. The particle size of the aggregate is 3 mm to 6 mm; the dosage of the aggregate is 80 parts to 200 parts, and the dosage of water is 100 parts to 200 parts.

[0016] The beneficial effects of the present invention are: Based on the problem that the performance of the existing super-strong cement-based cementitious material deteriorates after being used in an environment with high chloride ion content for a period of time, the addition of mineral fiber maintains the performance stability because the mineral fiber plays a role of skeleton connection, plays a role of hooking and fusing for the cement-based cementitious material, improves the elastic modulus and compressive capacity, and improves the quality of this inorganic cementitious material.

[0017] Add mineral fiber to a high-speed disperser, which ensures that the mineral fiber has a certain fluidity and does not agglomerate, so that it can better adhere to the dispersive cement material to play a role in property improvement.

[0018] The addition of boron oxide can improve the thermal stability and chemical resistance of mineral fibers, enabling the mineral fibers to maintain performance stability when mixed with cement in the coated state and avoiding the problem of losing the characteristics of mineral fibers. Boron oxide itself has poor crystallinity and thermal stability. During the process of mixing materials with water to form concrete, heat is generated up to 50°C to 70°C, which can easily cause the mineral fibers to agglomerate with the cement base materials due to uneven heating. However, due to the thermal stability, dispersibility, and non-crystallization characteristics of boron oxide, it can maintain or delay the local uneven agglomeration between molecules, thereby controlling the uneven agglomeration of mineral fibers with other cement materials and improving the quality of the final concrete. Brief Description of the Drawings

[0019] Figure 1 It is a physical picture of the cement crack in the experimental example of the improved preparation method of the inorganic cementitious material of the present invention.

[0020] Figure 2 It is a summary graph of the statistical results of different crack lengths. Detailed Embodiments

[0021] Embodiment

[0022] An improved preparation method of a super-strong cement-based inorganic cementitious material in this embodiment includes the following steps:

[0023] Step 1: 100 parts of Portland cement, 10 parts of silica fume, and 20 parts of fly ash are superfine mixed to obtain a super-strong cement base material; superfine mixing means that the particle size is controlled below 20 microns.

[0024] Step 2: The mixed materials are coated, mineral fibers are added in stages and continuously stirred and mixed; in addition, a boron oxide modifier is added simultaneously and evenly mixed; different weights of mineral fibers and boron oxide modifiers are added to obtain different proportion embodiments, and the specific components of different embodiments are shown in the following table. Coating means mixing with mineral fibers and coating the mineral fibers, or evenly dispersing the mineral fibers in the cement base material. Staging means dividing the materials in Step 1 into multiple additions for better mixing.

[0025] Step 3: First, 10 parts of superfine limestone powder and 10 parts of superfine steel slag powder are added, then 1 part of high-range water reducer and 1 part of rheology modifier are added. In addition, a boron oxide modifier is added simultaneously and evenly mixed. The particle sizes of the superfine limestone and superfine steel slag powder are less than 20 microns.

[0026] The beneficial effects of the present invention are as follows: Based on the problem that the performance of existing super-strong cement-based cementitious materials deteriorates after being used in an environment with a high chloride ion content for a period of time, the addition of mineral fibers maintains the performance stability. This is because the mineral fibers play a role in skeleton connection and have a connecting and fusing effect on the cement-based cementitious materials, improving the elastic modulus and compressive capacity, and enhancing the quality of this inorganic cementitious material. The addition of ultrafine steel slag powder can effectively play the roles of waterproofing and anti-corrosion and oxidation.

[0027] Add mineral fibers and a rheological agent to a high-speed disperser (new type mixer), which ensures that the mineral fibers have a certain fluidity and do not agglomerate, so that they can be better bonded and adhered to the dispersive cement materials to play a role in property improvement. Through the control of agglomeration by the high-speed disperser, the mineral fibers are completely dispersed without agglomeration, that is, when in a completely dispersed state, they are more easily fused with the cement base materials and maintain the original characteristics of the mineral fibers.

[0028] The addition of boron oxide can improve the thermal stability and chemical resistance of the mineral fibers, so that the mineral fibers maintain performance stability when mixed with cement in the coated state, avoiding the problem of losing the characteristics of the mineral fibers. Boron oxide itself has the characteristics of difficult crystallization and thermal stability. When the material is mixed with water to form concrete, heat will be generated up to 50°C to 70°C, which is likely to cause the mineral fibers to agglomerate with the cement base materials due to uneven heating. However, through the thermal stability, dispersibility and non-crystallization characteristics of boron oxide, it can maintain or delay the local uneven agglomeration between molecules, thereby controlling the uneven agglomeration of the mineral fibers and other cement materials and improving the quality of the final concrete.

[0029] Table 1 shows the components of the materials with 100 parts of inorganic cementitious materials and different weight ratios of mineral fibers and boron oxide added in different embodiments. It can be prepared according to the above steps. In the following table, the total mass of the inorganic cementitious materials in the embodiments is 100 parts, and the total proportion of mineral fibers and boron oxide is given separately.

[0030] Inorganic cementitious material Mineral fiber Boron oxide Example 1 100 1 0.1 Example 2 100 0.6 0.06 Example 3 100 0.2 0.02 Example 4 100 0.1 0.01 Control Example 1 100 0 0 Control Example 2 100 1 0

[0031] As can be seen from Table 1 above, in Examples 1 to 4, different gravity ratios of mineral fibers were added for modification, the weight parts of the inorganic cementitious materials were all 100, and the total parts of the added mineral fibers were from 1 to 0.1. Correspondingly, the added amount of boron oxide was 10% of the mineral fibers.

[0032] In addition, in Comparative Example 1, no mineral fibers were added to form a comparative control experiment. Furthermore, in Comparative Example 2, the added amount of mineral fibers was 1, and the added amount of boron oxide was 0, thus forming a difference to verify the influence of the added boron oxide on the material modification.

[0033] The samples obtained from the above-mentioned Example 1 and Comparative Example 1 were subjected to sample testing. According to the existing testing techniques, their compressive strength and elastic modulus were measured. The following tabular data were obtained. As can be seen in Table 2, the compressive strength of this modified concrete material reached 190, while that of the comparative example was 140, and the elastic modulus was 60, while that of Comparative Example 1 was 45. This shows that after the samples obtained in Example 1 of the present invention were made into concrete, both their compressive strength and elastic modulus were significantly improved.

[0034] The cement materials in Table 2 were made into concrete, that is, the super-strong cement-based inorganic binder obtained by improving the preparation method was mixed with aggregates and water to form a concrete structure. The particle size of the aggregates was from 1 mm to 7 mm. The aggregates included coarse aggregates and fine aggregates. The fine aggregates were sand and gravel, and the coarse aggregates were diabase; the dosage of each aggregate was 80 parts, and the dosage of water was 200 parts. Then the following data in Table 2 were obtained after testing.

[0035] Experimental example: The cement components of different component examples were subjected to construction verification, and the strength changes were observed in a saline environment. The amount of sodium chloride in the saline environment was 20% by mass ratio, and this mass ratio was several times the seawater concentration of the saline water to achieve corrosion in a more severe environment to observe the strength changes of the cement; observations were made after immersion in the saline environment for 12 months and 24 months.

[0036] Table 2

[0037]

[0038] As can be seen in Table 2, the concrete of Example 1 showed stability after 12 months and 24 months, and there was no problem of decrease in compressive strength and elastic modulus. However, in the comparative example, a slight decrease occurred after 24 months, which shows that the cement of the present invention has been improved and its performance stability has been enhanced.

[0039] Table 3. After immersion for 24 months, observations were made on the statistical analysis of the surface crack areas after construction under the conditions of the experimental example for different examples.

[0040] Group Number of cracks (X < 1 cm) Number of cracks (1 cm ≤ X < 5 cm) Number of cracks (5 cm ≤ X) Example 1 <![CDATA[2.2 / m 2 > <![CDATA[2.8 / m 2 > <![CDATA[0.3 / m 2 > Control Example 1 <![CDATA[5.8 / m 2 > <![CDATA[7.5 / m 2 > <![CDATA[2.6 / m 2 > Control Example 2 <![CDATA[3.3 / m 2 > <![CDATA[5.2 / m 2 > <![CDATA[0.9 / m 2 >

[0041] In the experimental example, after the cement surface was obtained after erosion in salt water for 24 months, Figure 1 The figure shows an actual photo of Comparative Example 1. That is, data statistics were carried out according to the number of cracks in the photo, that is, the number of cracks in each square meter area was counted, and the number of cracks of different sizes and lengths was counted to be summarized in the above Table 3 and Figure 2 in.

[0042] From these data, it can be seen that the number of cracks in Comparative Example 1 is relatively large, while the number of cracks in Example 1 with improved properties is reduced. Especially for the case where the crack length is greater than 5 cm, there is a significant decrease, which indicates that the addition of the mineral fiber of the present invention improves the flexibility of the concrete components, and the number of cracks on the concrete surface is significantly inhibited under the erosion of a harsh brine environment.

[0043] It should be noted that the number of cracks greater than 5 cm affects the quality of the wall, and this inhibitory effect is more significant. Cracks less than 5 cm have basically no impact on the building quality, but only have a certain impact on the flatness and appearance of the outer surface.

[0044] Furthermore, for Comparative Example 2, boron oxide was not added, and the number of cracks is higher than that in Example 1, which indicates that the addition of boron oxide improves the performance, that is, through the property of thermal stability, the performance of the added mineral fiber is more stable, avoiding the problem of performance damage of the mineral fiber.

[0045] In Figure 2 , the data is more intuitively statistically analyzed, and it can be seen that the cracks in the Example 1 group have been significantly improved, whether they are small cracks or large cracks.

[0046] The mineral fiber is a mineral fiber, for example, the commercially available Bote mineral fiber is used.

Claims

1. A method for improving the preparation of a super-strong cement-based inorganic cementitious material, characterized in that, It includes the following steps: Step 1: Superfine mix portland cement, silica fume, and fly ash to obtain a mixed material of super-strong cement base material; Step 2: Coating the mixed material, adding mineral fibers in stages and continuously stirring and mixing. Additionally, add boron oxide modifier simultaneously and mix evenly; Step 3: First add superfine limestone powder and superfine steel slag powder, then add high-range water reducer and rheology modifier, and mix evenly.

2. The preparation method for improving the super-strong cement-based inorganic cementitious material according to claim 1, characterized in that, The dosage ratio of mineral fiber to super-strong cement base material is 1:100 to 0.1:

100.

3. The preparation method for improving the super-strong cement-based inorganic cementitious material according to claim 1, characterized in that After the staged modification in Step 2, it is carried out in a new type of mixer and modifier.

4. The preparation method for improving the super-strong cement-based inorganic cementitious material according to claim 1, characterized in that, The dosage components are: 100 parts of portland cement, 10 parts of silica fume, 20 parts of fly ash, 1 to 5 parts of high-range water reducer and rheology modifier, 10 parts of superfine limestone powder, and 10 parts of superfine steel slag powder.

5. The preparation method for improving the super-strong cement-based inorganic cementitious material according to claim 4, characterized in that, Boron oxide is 5% to 20% of the dosage ratio of mineral fiber.

6. The preparation method for improving the super-strong cement-based inorganic cementitious material according to any one of claims 1 to 5, characterized in that, The high-range water reducer is a sulfonate-based or lignosulfonate-based or polycarboxylate-based water reducer.

7. The preparation method for improving the super-strong cement-based inorganic cementitious material according to any one of claims 1 to 5, characterized in that, The super-strong cement-based inorganic cementitious material obtained by the improved preparation method is mixed with aggregate and water to form a concrete structure. The particle size of the aggregate is 1 mm to 7 mm. The aggregate includes coarse aggregate and fine aggregate. The fine aggregate is sand and gravel, and the coarse aggregate is diabase; the dosage of the aggregate is 80 to 200 parts, and the dosage of water is 100 to 200 parts.

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