Super-early-strength grouting material and preparation method thereof

Abstract

The invention discloses a super-early-strength grouting material and a preparation method thereof, and belongs to the technical field of building materials. The concrete comprises the following components in parts by weight: 81-93 parts of composite cement, 3-8 parts of silica fume, 4-9 parts of nano metakaolin, 0.1-0.8 part of lithium carbonate, 0.3-1.5 parts of a water reducing agent, 0.05-0.2 part of a defoaming agent and mixing water, and the water-to-material ratio of the grouting material is 0.14 to 0.18. The grouting material prepared from the cement compounded by the sulphoaluminate cement, the aluminate cement and the gypsum has relatively high early strength and also has relatively good workability and micro-expansion performance; wherein the silica fume and the nano metakaolin obviously improve the workability of the slurry and effectively inhibit the strength shrinkage of the slurry; the raw materials used in the method are easy to obtain, operation is easy, and the method is suitable for grouting scenes with high requirements for early strength, workability and construction convenience.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of building materials, and particularly relates to a super-early-strength grouting material and a preparation method thereof. BACKGROUND

[0002] Grouting materials are widely used in building engineering. With the rapid development of building materials and construction technology, cement-based grouting materials are widely used in crack repair, engineering reinforcement and repair. The flow performance and physical and mechanical properties of grouting materials directly determine whether the grouting engineering is successful. However, in grouting engineering, complex and changeable construction environments are often faced, especially in engineering reinforcement and repair operations, and the performance requirements of grouting materials are higher.

[0003] Application No. 202311784001.5 discloses the preparation of a super-early-strength grouting material using sulphoaluminate cement, which has high early strength but is expensive. The cement completely uses sulphoaluminate cement, which has a short setting time, which easily leads to construction risks. Application Nos. 202410600291.1 and 201810095594.7 both disclose the preparation of grouting materials using sulphoaluminate cement and Portland cement, which has high impermeability and other properties, but the strength performance is poor. Due to the characteristics of gypsum materials, the setting time, strength and volume stability of cement can be controlled within a certain range. Based on this, a super-early-strength grouting material is prepared by using sulphoaluminate cement, aluminate cement and gypsum. SUMMARY

[0004] The purpose of the present application is to provide a super-early-strength grouting material and a preparation method thereof, which solves the problems of high cost of grouting materials prepared by simply using sulphoaluminate cement and poor strength performance of grouting materials prepared by using sulphoaluminate cement and Portland cement. The grouting material has high early strength while meeting the workability, and can be well applied to crack repair, engineering reinforcement and repair.

[0005] The purpose of the present application can be achieved by the following technical solutions: A super-early-strength grouting material, comprising composite cement, microsilica powder, nano-metakaolin, lithium carbonate, water reducing agent, defoaming agent and mixing water.

[0006] Further, the weight ratio of the composite cement, microsilica powder, nano-metakaolin, lithium carbonate, water reducing agent and defoaming agent is (81-93):(3-8):(4-9):(0.1-0.8):(0.3-1.5):(0.05-0.2).

[0007] Further, the water-to-material ratio of the grouting material is 0.14-0.18.

[0008] Further, the composite cement is sulfaluminate cement, aluminate cement and gypsum in a weight ratio of (4-6):(1.5-3):(1-2.5).

[0009] Further, the microsilica powder contains not less than 95.0% of SiO2, and the specific surface area is not less than 25000 m 2 / kg.

[0010] Further, the nano metakaolin has a specific surface area of not less than 30000 m 2 / kg.

[0011] Further, the lithium carbonate is of industrial grade, and the content is not less than 99%.

[0012] Further, the water reducing agent is polycarboxylic acid high performance water reducing agent, white powder, and the water reducing rate is not less than 30%.

[0013] Further, the defoaming agent is powder organic silicon defoaming agent.

[0014] Further, the mixing water is tap water, and all indexes meet the relevant provisions of JGJ63 "Water Standard for Concrete".

[0015] A preparation method of an ultra-early-strength grouting material, comprising the following steps: The composite cement, microsilica powder, nano metakaolin, lithium carbonate, water reducing agent and defoaming agent are added into a stirrer and stirred for 3-5 minutes, then the mixing water is added into the stirrer and stirred uniformly, so that the ultra-early-strength grouting material is obtained.

[0016] The beneficial effects of the present application are as follows: (1) The sulfaluminate cement used in the present application provides extremely fast hydration speed and early strength skeleton, and the gypsum effectively controls the setting time and participates in the formation of ettringite and other expansive hydration products. The three components synergistically act in a specific ratio, not only ensuring that the grouting material can reach an ultra-high early strength of more than 15 MPa in a very short time (2 hours), but also endowing the grout with moderate micro-expansion characteristics, compensating for shrinkage and improving the bonding and compactness with the matrix. In addition, lithium carbonate can accelerate the hydration reaction of the cementitious materials in the grouting material, significantly improving the early strength of the grouting material; the water reducing agent can improve the fluidity of the grouting material at a low water-to-material ratio, ensuring its pumpability, while reducing the amount of mixing water to improve the compactness and strength; the defoaming agent can eliminate the air bubbles generated during the mixing process of the grouting material, avoid the formation of internal pores, and ensure the compactness and mechanical property stability of the grouting material; the mixing water, as the mixing medium of the solid components of the grouting material, participates in the hydration reaction of the cementitious materials, ensuring that the grouting material has a workable fluidity.

[0017] (2) The micro-silica powder used in the application has a high specific surface area and rich active SiO2, which plays a super-filling effect on one hand, and tightly accumulates in the gap between cement particles to greatly improve the density of the matrix; on the other hand, its high activity enables it to quickly react with Ca(OH)2 released by cement hydration to generate more C-S-H gel with cementitious properties, which not only improves early and late strength, but also effectively consumes Ca(OH)2 crystals that can easily lead to weak interfaces and late strength reduction. Nano-metakaolin further strengthens the filling effect and pozzolanic activity, and its nano-scale particles can penetrate into smaller pores, while providing active Al2O3 to promote the formation of complex and stable hydration products (C-A-S-H gel), significantly improving the uniformity and long-term stability of the paste structure, and jointly inhibiting the late strength reduction phenomenon commonly seen in high early strength materials, and optimizing the rheological properties of the paste.

[0018] (3) The application uses appropriate proportions to balance the functions of each component, and cooperatively ensures the ultra-early strength, density and workability of the grouting material, avoiding performance imbalance caused by excessive or insufficient single component. The raw materials used take into account high performance and easy availability, and the composite cement component, micro-silica powder, nano-metakaolin and various additives are all commonly used industrial materials that do not require special preparation; the operation process is simple, and workers can master it after being briefed, reducing the construction technical threshold and performance fluctuations caused by complex operation, and being suitable for grouting scenes with high requirements for early strength, workability and construction convenience. DETAILED DESCRIPTION

[0019] The application provides an ultra-early strength grouting material, which comprises composite cement, micro-silica powder, nano-metakaolin, lithium carbonate, water reducing agent, defoaming agent and mixing water.

[0020] In some embodiments, the weight ratio of the composite cement, micro-silica powder, nano-metakaolin, lithium carbonate, water reducing agent and defoaming agent is (81-93):(3-8):(4-9):(0.1-0.8):(0.3-1.5):(0.05-0.2).

[0021] Preferably, the weight ratio of the composite cement, micro-silica powder, nano-metakaolin, lithium carbonate, water reducing agent and defoaming agent is 88:4:6:0.5:0.8:0.08.

[0022] The above components and proportions can balance the functions of each component, and cooperatively ensure the ultra-early strength, density and workability of the grouting material, avoiding performance imbalance caused by excessive or insufficient single component.

[0023] In some embodiments, the water-to-material ratio of the grouting material is 0.14-0.18. Setting a suitable water-to-material ratio can take into account the fluidity of the paste and the density of the hardened body, reducing the pores formed by excess water and laying a foundation for high strength development.

[0024] In some embodiments, the composite cement is a combination of sulphoaluminate cement, aluminate cement and gypsum in a weight ratio of (4-6):(1.5-3):(1-2.5).

[0025] Preferably, the weight ratio of sulphoaluminate cement, aluminate cement and gypsum is 5:2:1.8. The three components work together to achieve a 2h≥15MPa ultra-early strength performance, while regulating the setting time, generating ettringite to impart micro-expansion, and avoiding the problems of high cost or rapid setting of pure sulphoaluminate cement.

[0026] In some embodiments, the microsilica has a silicon dioxide content of not less than 95.0%, and a specific surface area of not less than 25000m 2 / kg. The high-activity silicon dioxide can participate in the pozzolanic reaction to generate cementitious products, and the large specific surface area can achieve ultra-fine filling, optimizing the pore structure of the paste and inhibiting the late strength reversal.

[0027] In some embodiments, the nano-metakaolin has a specific surface area of not less than 30000 m 2 / kg. The nano-sized particles can penetrate into the micro-pores to strengthen the filling, while providing active aluminum to promote the generation of stable C-A-S-H gel, improving the uniformity and long-term stability of the paste.

[0028] In some embodiments, the lithium carbonate is of industrial grade, with a content of not less than 99%. High purity ensures efficient acceleration of the cement hydration process, and synergistically improves the early strength, avoiding the performance fluctuations caused by impurities interfering with the hydration reaction.

[0029] In some embodiments, the water reducing agent is a polycarboxylic acid high-performance water reducing agent, which is a white powder with a water-reducing rate of not less than 30%. It can effectively disperse the cementitious particles at a low water-cement ratio, ensuring the initial and 30min fluidity of the paste, and reducing the amount of mixing water to improve the density

[0030] In some embodiments, the defoaming agent is a powdered silicone defoaming agent. It can eliminate the air bubbles generated during the mixing process, preventing the formation of internal pores after hardening, and further ensuring the density and compressive strength of the paste.

[0031] The specific embodiments of the present application are described in detail below, but it should be understood that the scope of protection of the present application is not limited by the specific embodiments.

[0032] Example 1

[0033] This embodiment provides an ultra-early strength grouting material, which is prepared by the following steps: The composite cement 88 parts, microsilica powder 4 parts, nano metakaolin 6 parts, lithium carbonate 0.5 parts, water reducing agent 0.8 parts, defoaming agent 0.08 parts and 14.9 parts of mixed water (water material ratio is 0.15) are added into the stirrer and stirred for 5 minutes, and then the mixed water is added into the stirrer and stirred uniformly to obtain the ultra-early strength grouting material; The composite cement is 50 parts of sulphoaluminate cement, 20 parts of aluminate cement and 18 parts of gypsum by weight; The microsilica powder contains 99.1% of silicon dioxide and has a specific surface area of 28000 m 2 / kg; The nano metakaolin has a specific surface area of 31000 m 2 / kg; The lithium carbonate has a content of not less than 99% and is an industrial grade; The water reducing agent is a polycarboxylic acid high-performance water reducing agent, which is a white powder and has a water reducing rate of 36%; The defoaming agent is a powdery organic silicon defoaming agent; The mixed water is tap water, and all indexes meet the relevant provisions of JGJ63 "Concrete Water Standard".

[0034] Example 2

[0035] The composite cement 90 parts, microsilica powder 4 parts, nano metakaolin 5 parts, lithium carbonate 0.7 parts, water reducing agent 1.0 parts, defoaming agent 0.1 parts and 16.1 parts of mixed water (water material ratio is 0.16) are added into the stirrer and stirred for 5 minutes, and then the mixed water is added into the stirrer and stirred uniformly; The composite cement is 55 parts of sulphoaluminate cement, 20 parts of aluminate cement and 15 parts of gypsum by weight; The microsilica powder contains 98.2% of silicon dioxide and has a specific surface area of 26500 m 2 / kg; The nano metakaolin has a specific surface area of 31000 m 2 / kg; The lithium carbonate has a content of not less than 99% and is an industrial grade; The water reducing agent is a polycarboxylic acid high-performance water reducing agent, which is a white powder and has a water reducing rate of 38%; The defoaming agent is a powdery organic silicon defoaming agent; The mixed water is tap water, and all indexes meet the relevant provisions of JGJ63 "Concrete Water Standard".

[0036] The remaining raw materials and preparation process are the same as those of Example 1.

[0037] Example 3

[0038] The embodiment is compared with example 1, the difference lies in, the dosage of gypsum in composite cement is reduced, the dosage of nano metakaolin is increased, the specific steps are as follows: The composite cement 85 parts, the microsilica powder 6 parts, the nano metakaolin 9 parts, the lithium carbonate 0.3 parts, the water reducing agent 0.5 parts, the defoaming agent 0.05 parts and 14.3 parts of mixed water (water material ratio 0.14) are added into the mixer and stirred for 4 min, and then stirred to be uniform after mixing uniformly; The composite cement is as follows in weight parts: the sulphoaluminate cement 52 parts, the aluminate cement 25 parts, the gypsum 12 parts; The microsilica powder is as follows: the content of silicon dioxide 96.5%, the specific surface area 27000 m 2 / kg; the nano metakaolin is as follows: the specific surface area 32000 m 2 / kg.

[0039] The rest of the raw materials and the preparation process are the same as example 1.

[0040] Example 4

[0041] The embodiment is compared with example 1, the difference lies in, the dosage of microsilica powder is increased, the dosage of lithium carbonate is reduced, the specific steps are as follows: The composite cement 81 parts, the microsilica powder 8 parts, the nano metakaolin 7 parts, the lithium carbonate 0.1 parts, the water reducing agent 1.2 parts, the defoaming agent 0.15 parts and 15.8 parts of mixed water (water material ratio 0.17) are added into the mixer and stirred for 3 min, and then stirred to be uniform after mixing uniformly; The composite cement is as follows in weight parts: the sulphoaluminate cement 48 parts, the aluminate cement 22 parts, the gypsum 16 parts; The microsilica powder is as follows: the content of silicon dioxide 97.8%, the specific surface area 29000 m 2 / kg; the nano metakaolin is as follows: the specific surface area 30500 m 2 / kg.

[0042] The rest of the raw materials and the preparation process are the same as example 1.

[0043] Example 5

[0044] The embodiment is compared with example 1, the difference lies in, the dosage of composite cement is increased, the water material ratio is reduced, the specific steps are as follows: The composite cement 93 parts, the microsilica powder 3 parts, the nano metakaolin 4 parts, the lithium carbonate 0.6 parts, the water reducing agent 0.3 parts, the defoaming agent 0.2 parts and 13.0 parts of mixed water (water material ratio 0.14) are added into the mixer and stirred for 5 min, and then stirred to be uniform after mixing uniformly; The composite cement is as follows in weight parts: the sulphoaluminate cement 60 parts, the aluminate cement 30 parts, the gypsum 25 parts; The microsilica powder is as follows: the content of silicon dioxide 95.8%, the specific surface area 25500 m2 / kg; nano metakaolin specific surface area 31500 m 2 / kg.

[0045] The remaining raw materials and preparation process remain the same as in Example 1.

[0046] Example 6

[0047] The difference between this example and Example 1 is that the amount of water reducing agent is increased, and the water material ratio is increased. The specific steps are as follows: The composite cement 90 parts, microsilica 5 parts, nano metakaolin 8 parts, lithium carbonate 0.8 parts, water reducing agent 1.5 parts, defoaming agent 0.12 parts and 16.6 parts of mixed water (water material ratio 0.18) are added into the mixer and stirred for 4 min. After mixing evenly, it is stirred to uniformity; The composite cement is as follows in weight parts: sulphoaluminate cement 45 parts, aluminate cement 28 parts, gypsum 20 parts; The microsilica has a silicon dioxide content of 98.5% and a specific surface area of 28500 m 2 / kg; nano metakaolin specific surface area 32500 m 2 / kg.

[0048] The remaining raw materials and preparation process remain the same as in Example 1.

[0049] Comparative Example 1

[0050] The difference between this example and Example 1 is that 100 parts of sulphoaluminate cement is used to replace the composite cement (no aluminate cement, gypsum). The specific steps are as follows: The sulphoaluminate cement 88 parts (the original composite cement 88 parts is replaced by pure sulphoaluminate cement), microsilica 4 parts, nano metakaolin 6 parts, lithium carbonate 0.5 parts, water reducing agent 0.8 parts, defoaming agent 0.08 parts and 14.9 parts of mixed water (water material ratio 0.15) are added into the mixer and stirred for 5 min. After mixing evenly, it is stirred to uniformity; The remaining raw materials and preparation process remain the same as in Example 1.

[0051] Comparative Example 2

[0052] The difference between this example and Example 1 is that the composite cement is replaced by "sulphoaluminate cement: Portland cement = 1:1" (no aluminate cement, gypsum). The specific steps are as follows: The composite cement 88 parts (sulphoaluminate cement 44 parts and Portland cement 44 parts), microsilica 4 parts, nano metakaolin 6 parts, lithium carbonate 0.5 parts, water reducing agent 0.8 parts, defoaming agent 0.08 parts and 14.9 parts of mixed water (water material ratio 0.15) are added into the mixer and stirred for 5 min. After mixing evenly, it is stirred to uniformity; The remaining raw materials and preparation process are the same as Example 1.

[0053] Comparative Example 3

[0054] The present comparative example is different from Example 1 in that the microsilica powder is removed, and the remaining components are proportionally adjusted (the composite cement is increased to 92 parts to make up for the lack of microsilica powder). The specific steps are as follows: The composite cement 92 parts (the original 88 parts and the replacement amount of 4 parts of microsilica powder), nano-metakaolin 6 parts, lithium carbonate 0.5 parts, water reducing agent 0.8 parts, defoaming agent 0.08 parts, and 14.9 parts of mixed water (water material ratio 0.15) are added into the mixer and stirred for 5 min. After mixing uniformly, it is stirred again to homogenize; The remaining raw materials and preparation process are the same as Example 1.

[0055] Comparative Example 4

[0056] The present comparative example is different from Example 1 in that the nano-metakaolin is removed, and the remaining components are proportionally adjusted (the composite cement is increased to 94 parts to make up for the lack of nano-metakaolin). The specific steps are as follows: The composite cement 94 parts (the original 88 parts and the replacement amount of 6 parts of nano-metakaolin), microsilica powder 4 parts, lithium carbonate 0.5 parts, water reducing agent 0.8 parts, defoaming agent 0.08 parts, and 14.9 parts of mixed water (water material ratio 0.15) are added into the mixer and stirred for 5 min. After mixing uniformly, it is stirred again to homogenize; The remaining raw materials and preparation process are the same as Example 1.

[0057] Comparative Example 5

[0058] The present comparative example is different from Example 1 in that the lithium carbonate is removed, and the remaining components remain unchanged. The specific steps are as follows: The composite cement 88 parts, microsilica powder 4 parts, nano-metakaolin 6 parts, water reducing agent 0.8 parts, defoaming agent 0.08 parts, and 14.9 parts of mixed water (water material ratio 0.15) are added into the mixer and stirred for 5 min. After mixing uniformly, it is stirred again to homogenize; The remaining raw materials and preparation process are the same as Example 1.

[0059] Comparative Example 6

[0060] The present comparative example is different from Example 1 in that the amount of gypsum in the composite cement exceeds the upper limit (3 parts, exceeding the range of 1~2.5). The specific steps are as follows: The composite cement 88 parts (sulfoaluminate cement 50 parts, aluminate cement 20 parts, and gypsum 30 parts, with gypsum accounting for 3 parts), microsilica powder 4 parts, nano-metakaolin 6 parts, lithium carbonate 0.5 parts, water reducing agent 0.8 parts, defoaming agent 0.08 parts, and 14.9 parts of mixed water (water material ratio 0.15) are added into the mixer and stirred for 5 min. After mixing uniformly, it is stirred again to homogenize; The remaining raw materials and preparation process are the same as in Example 1.

[0061] Performance test

[0062] According to GB / T 50448-2015 "Technical Specification for Application of Cement-based Grouting Materials", the super early strength grouting material prepared from Example 1 to Example 6 and Comparative Example 1 to Comparative Example 6 is tested as follows: 1. Fluidity: test initial fluidity and 30 min fluidity; 2. Compressive strength: test 2h, 3d, 28d compressive strength; 3. Vertical expansion rate: test 3h vertical expansion rate and the difference between 24h and 3h expansion rate (specification requires 3h≥0.1%, 24h difference≤0.15%); The results are shown in Table 1: Table 1

[0063] As can be seen from Table 1, the initial fluidity is 305-340mm, the 30min fluidity is 260-290mm, which is much higher than that of the comparative examples (220-290mm), indicating that the synergistic effect of composite cement and admixture can ensure good fluidity; the 2h compressive strength is 16.8-21.5MPa (all >15MPa), the 3d strength is 56.8-62.8MPa, and the 28d strength is 59.3-65.5MPa (no strength reversal), which reflects the characteristics of super early strength and long-term stable strength; the 3h vertical expansion rate is 0.12%-0.20% (specification≥0.1%), and the difference between 24h and 3h is 0.05%-0.12% (specification≤0.15%), which can effectively compensate for shrinkage and improve bonding density.

[0064] Comparative Example 1 (pure sulphoaluminate cement) 2h strength 14.2MPa (lower than Example 8.5MPa), 28d strength 42.8MPa (reversal occurs), fluidity 280mm (poor workability), and the cost of pure sulphoaluminate cement is 30%-40% higher than that of composite cement; Comparative Example 2 (sulphoaluminate-silicate composite) 2h strength only 8.5MPa (much lower than Example 15MPa threshold), 28d strength 36.2MPa (serious reversal), indicating that the hydration compatibility of silicate cement and sulphoaluminate cement is poor.

[0065] The fluidity of the comparative example 3 is reduced to 260 mm, the 2h strength is 12.7 MPa, and the 28d strength is reversed; the 28d strength of the comparative example 4 is 47.9 MPa (reversed) after the nano metakaolin is omitted, which indicates that the "nano filling + C-A-S-H gel generation" can inhibit the strength reversal; the 2h strength of the comparative example 5 is only 9.8 MPa after the lithium carbonate is omitted, which proves the early strength synergistic effect of the "accelerating hydration nucleation"; the difference between the 24h and 3h expansion rates of the comparative example 6 is 0.25% (over standard) after the gypsum is over-proportioned, which is easy to cause the hardened body to crack, and which proves the importance of the proportion control of the gypsum in the composite cement.

[0066] The above disclosure is only several specific embodiments of the present application, but the embodiments of the present application are not limited thereto, and any changes that can be thought of by any person skilled in the art shall fall within the protection scope of the present application.

Claims

1. An ultra-early strength grouting material, characterized in that, The composite cement, the microsilica powder, the nano metakaolin, the lithium carbonate, the water reducing agent, the defoaming agent and the mixing water are 81-93 parts, 3-8 parts, 4-9 parts, 0.1-0.8 parts, 0.3-1.5 parts, 0.05-0.2 parts and 0.1-0.8 parts by weight respectively.

2. The ultra-high early-strength grouting material according to claim 1, characterized in that, The water-material ratio of the grouting material is 0.14-0.

18.

3. The ultra-high early-strength grouting material according to claim 1, characterized in that, The composite cement is a composite of sulphoaluminate cement, aluminate cement and gypsum in a weight ratio of (4-6):(1.5-3):(1-2.5).

4. The ultra-high early-strength grouting material according to claim 1, wherein The microsilica silicon dioxide content is not less than 95.0%, the specific surface area is not less than 25000 m 2 / kg.

5. The ultra-high early-strength grouting material according to claim 1, wherein The nano-partially kaolin has a specific surface area not less than 30000 m 2 / kg.

6. The ultra-high early-strength grouting material according to claim 1, wherein The lithium carbonate is an industrial grade with a content of not less than 99%.

7. The ultra-high early-strength grouting material according to claim 1, wherein The water reducing agent is a polycarboxylic high-performance water reducing agent in white powder form with a water-reducing rate of not less than 30%.

8. The ultra-high early-strength grouting material according to claim 1, wherein, The defoaming agent is a powdered organic silicon defoaming agent.

9. The ultra-high early-strength grouting material according to claim 1, wherein The mixing water is tap water, and all indexes meet the relevant provisions of JGJ63 'Water Standard for Concrete'.

10. A method for preparing an ultra-high early-strength grouting material, characterized by, The method for preparing the ultra-early-strength grouting material of any one of claims 1-9 comprises the following steps: The composite cement, the microsilica powder, the nano metakaolin, the lithium carbonate, the water reducing agent and the defoaming agent are added into a stirrer and stirred for 3-5 minutes, and then the mixing water is added into the stirrer and stirred until uniform, to obtain the ultra-early-strength grouting material. The composite cement, the microsilica powder, the nano metakaolin, the lithium carbonate, the water reducing agent and the defoaming agent are added into a stirrer and stirred for 3-5 minutes, and then the mixing water is added into the stirrer and stirred until uniform, to obtain the ultra-early-strength grouting material.

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