High-durability anti-freezing composite grouting material and preparation method thereof

Abstract

The invention belongs to the technical field of building materials, and particularly discloses a high-durability anti-freezing composite grouting material and a preparation method thereof. The high-durability anti-freezing composite grouting material comprises the following components: cement, silica fume, fly ash, aggregate, water, a composite air entraining agent, polypropylene fibers and an additive, the aggregate is quartz sand, the composite air entraining agent comprises modified polycarboxylate and nano aerogel, and the additive comprises a water reducing agent and nano aluminum oxide. By optimizing the material ratio and introducing the composite air entraining agent and the polypropylene fiber, the compressive strength, the freeze-thaw durability, the construction fluidity and the dimensional stability of the slurry are improved, so that the slurry is more suitable for constructional engineering in severe cold areas, and the problems existing in application of an existing cement-based grouting material in the severe cold areas are solved; in addition, the grouting material also has the cost advantage, and the market competitiveness is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to a high-durability anti-freezing composite grouting material and a preparation method thereof. BACKGROUND

[0002] Cement-based grouting materials are widely used in the fields of building structure reinforcement, equipment foundation grouting, prestressed duct filling, bridge support installation, etc. due to their good bonding performance, high early strength and convenient construction. However, in severe cold regions or low temperature environments, the performance of traditional cement-based grouting materials shows obvious shortcomings, mainly in the aspects of insufficient frost resistance, poor construction fluidity, low dimensional stability, etc., which seriously restricts their engineering application effect.

[0003] In view of the problems existing in the application of traditional cement-based grouting materials in severe cold regions, the existing technology attempts to improve by adjusting the material ratio, introducing additives or admixtures, etc., for example:

[0004] Chinese invention patent application CN115093180A discloses a freeze-proof non-shrinkage grouting material, which is configured by mixing and adding gel material, aggregate, defoaming agent, silk protein spun fiber, silica fume and air entraining agent. The frost resistance and freeze-proof effect of the grouting material are improved as a whole by selecting the type of aggregate, controlling the water-binder ratio, absorbing the air content and controlling the air bubble spacing, but the dimensional stability is not improved, and the performance index parameters of the grouting material are not provided, so it is difficult to judge the quality level of the grouting material.

[0005] Chinese invention patent application CN117800677A discloses a salt-resistant and freeze-resistant high-durability concrete, which is prepared from fly ash, cement, sand, stone, modified nano-silicon dioxide, modified polyacrylonitrile fiber additive and water. The prepared concrete has good salt resistance, freeze resistance and durability, but it does not have advantages in fluidity, expansion rate and strength, and is not as good as the present application.

[0006] In the academic paper "Influence of Air Entraining Agent on Frost Resistance of New Cement-based Materials" (Song Pengcheng, 2010), it is mentioned that the frost resistance of the material can be improved by adding an air entraining agent, but the combination of fluidity optimization and fiber reinforcement technology is not involved, and it is difficult to successfully apply it to cement-based grouting materials with multiple component and multi-functional requirements.

[0007] In summary, while the existing technology improves the frost resistance of cement-based grouting materials, it is often difficult to meet the requirements of construction fluidity, dimensional stability and mechanical properties, etc. SUMMARY

[0008] The present application aims to solve the problems of insufficient frost resistance, poor construction fluidity and low dimensional stability of existing cement-based grouting materials in the application in severe cold regions. By optimizing the material ratio, introducing composite air entraining agent and polypropylene fiber, the compressive strength, freeze-thaw durability, construction fluidity and dimensional stability of the slurry are improved, so that it is more suitable for building engineering in severe cold regions.

[0009] To achieve the above purpose, the specific technical solutions adopted by the present application are as follows:

[0010] In the first aspect, the present application provides a high durability frost-resistant composite grouting material, which comprises the following components: cement, silica fume, fly ash, aggregate, water, composite air entraining agent, polypropylene fiber and admixture; the aggregate is quartz sand, the composite air entraining agent comprises modified polycarboxylate and nano aerogel, and the admixture comprises water reducing agent and nano aluminum oxide.

[0011] Preferably, the high durability frost-resistant composite grouting material comprises, by weight: cement 55-65 parts, silica fume 5-15 parts, fly ash 10-20 parts, aggregate 25-35 parts, water 15-20 parts, composite air entraining agent 0.1-0.2 parts, polypropylene fiber 0.2-0.4 parts, water reducing agent 0.5-1.5 parts, and nano aluminum oxide 1-2 parts. Further preferably, the formula is: cement 60 parts, silica fume 10 parts, fly ash 15 parts, aggregate 30 parts, water 18 parts, composite air entraining agent 0.1 part, polypropylene fiber 0.3 part, water reducing agent 1 part, and nano aluminum oxide 1.5 parts.

[0012] Preferably, the composite air entraining agent is compounded as an air entraining agent by mixing modified polycarboxylate and nano aerogel at a mass ratio of (3-5):1, and further preferably at a mass ratio of 4:1. Through the synergistic effect of modified polycarboxylate and nano aerogel, the present application forms uniformly distributed closed micro-bubbles (diameter 10-200 μm) in the slurry, blocks the frost heaving stress transmission path, improves the frost resistance of the material, and has better frost resistance compared to other combinations or single air entraining agent.

[0013] Preferably, the length of the polypropylene fiber is 6-10 mm, and further preferably 6 mm. By adding polypropylene fiber, the crack resistance and dimensional stability of the material are enhanced.

[0014] Preferably, the cement is P.O52.5R portland cement, and 52.5R high-grade portland cement is selected, with the content of C3A (aluminate tricalcium) controlled at 5-8%, to provide basic strength as the main cementing phase.

[0015] Preferably, the aggregate is 0.1-1.2 mm graded quartz sand, which provides basic structural support and increases the overall strength and stability. By mixing quartz sand of different particle sizes, the particle size distribution is optimized, and the density and mechanical properties of the concrete are improved.

[0016] Preferably, silica fume with SiO2 content greater than 70% is selected as an active admixture, which can react with alkaline substances in cement to generate hydrated calcium silicate, improve strength and durability, and fill the voids between cement particles to increase the density of the grout, thereby improving impermeability and frost resistance.

[0017] Preferably, the water reducing agent is a polycarboxylic acid water reducing agent with a water reducing rate greater than 15%, a molecular weight of 8000-12000, a side chain density of 25-30%, and a copolymerization of phosphoric acid groups (-15.3 kJ / mol) and carboxylic acid groups (-9.8 kJ / mol). The advantage is that the water reducing rate is high, the shrinkage is small, the compatibility with the selected cement aggregate is good, and the early and late strength can be improved.

[0018] In a second aspect, the present application provides a preparation method of the high-durability frost-resistant composite grout as described above, comprising the following steps:

[0019] S1. Raw material preparation: weigh the cement, aggregate, silica fume, fly ash, water, and admixtures;

[0020] S2. Preparation of composite air entraining agent: mix various air entraining agents in proportion to prepare a composite air entraining agent;

[0021] S3. Grout preparation: mix and stir the cement, aggregate, silica fume, fly ash, water, and composite air entraining agent, then add polypropylene fibers and continue stirring until uniform;

[0022] S4. Molding and curing: pour the prepared grout into a mold for molding and curing for 28 days.

[0023] The high-durability frost-resistant composite grout of the present application significantly improves the compressive strength and durability of the grout by optimizing the ratio of cement, aggregate, water, and admixtures; uses a composite air entraining agent to improve the flowability of the grout, and the modified polycarboxylic acid ester in the composite air entraining agent cooperates with nano aerogel to form uniformly distributed closed micro-bubbles in the grout, blocking the frost heaving stress transmission path and improving the frost resistance; by adding polypropylene fibers, the material's crack resistance and dimensional stability are enhanced, and the polypropylene fibers + nano aluminum oxide form a "macro-micro" dual anti-cracking network to improve the residual strength after freezing and thawing; and by mixing, stirring, molding, and curing the raw materials to prepare the grout, the grout performance is ensured to be in the best state.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] 1. Excellent frost resistance: the combination of the composite air entraining agent and polypropylene fibers significantly improves the number of freeze-thaw cycles and the mass loss rate of the grout.

[0026] 2. Good construction performance: the grout has high flowability, facilitating construction and being suitable for complex engineering environments.

[0027] 3. Dimensional stability: The addition of polypropylene fibers significantly enhances the material's resistance to cracking and dimensional stability, extending its service life.

[0028] 4. Cost advantage: Optimized material proportions and production processes reduce production costs, improving market competitiveness. DETAILED DESCRIPTION

[0029] The invention will be further illustrated below with specific examples.

[0030] In the following examples, the graded quartz sand consists of 15wt% of 0.1mm quartz sand, 30wt% of 0.4mm quartz sand, 30wt% of 0.8mm quartz sand, and 25wt% of 1.2mm quartz sand; the modified polycarboxylate is a double-phosphonic group modified polycarboxylate, which is KM2110 product purchased from Guangzhou Jincheng Chemical Co., Ltd.; the nano-aerogel is AG-D product purchased from Shenzhen Zhongning Technology Co., Ltd.; and the polycarboxylate superplasticizer is PC-100T product purchased from Shanghai Yingshan New Materials Technology Co., Ltd.

[0031] Example 1 (Optimal Proportion)

[0032] A high frost resistance cement-based grout, comprising the following components: cement 60 parts, silica fume 10 parts, fly ash 15 parts, aggregate 30 parts, water 18 parts, composite air-entraining agent 0.1 part, polypropylene fiber 0.3 part (length 6mm), admixture 2.5 parts. Among them, the cement is specifically P.O52.5R portland cement; the aggregate is specifically graded quartz sand (0.1-1.2mm); the composite air-entraining agent includes the following mass parts of several air-entraining agents: modified polycarboxylate 0.08 parts, nano-aerogel 0.02 parts; the admixture includes: polycarboxylate superplasticizer 1 part, nano-alumina 1.5 parts.

[0033] Example 2 (Composite Air-Entraining Agent Dosage Adjustment)

[0034] A high frost resistance cement-based grout, comprising the following components: cement 60 parts, silica fume 10 parts, fly ash 15 parts, aggregate 30 parts, water 18 parts, composite air-entraining agent 0.2 parts, polypropylene fiber 0.3 part (length 6mm), admixture 2.5 parts. Among them, the cement is specifically P.O52.5R portland cement; the aggregate is specifically graded quartz sand (0.1-1.2mm); the composite air-entraining agent includes the following mass parts of several air-entraining agents: modified polycarboxylate 0.15 parts, nano-aerogel 0.05 parts; the admixture includes: polycarboxylate superplasticizer 1 part, nano-alumina 1.5 parts.

[0035] Example 3 (Polypropylene Fiber Length Adjustment)

[0036] A high frost resistance cement-based grouting material, comprising the following components: cement 60 parts, silica ash 10 parts, fly ash 15 parts, aggregate 30 parts, water 18 parts, composite air entraining agent 0.1 part, polypropylene fiber 0.3 part (length 10 mm), additive 2.5 parts. Wherein the cement is specifically P.O 52.5R Portland cement; the aggregate is specifically graded quartz sand (0.1-1.2 mm); the composite air entraining agent comprises the following mass parts of several air entraining agents: modified polycarboxylate 0.08 parts, nano aerogel 0.02 parts; the additive comprises: polycarboxylate superplasticizer 1 part, nano aluminum oxide 1.5 parts.

[0037] The slurries of examples 1-3 were prepared according to the following steps:

[0038] S1. Raw material preparation: weigh the cement, aggregate, silica ash, fly ash, water and additive;

[0039] S2. Composite air entraining agent preparation: mix the various air entraining agents in proportion to prepare the composite air entraining agent;

[0040] S3. Slurry preparation: mix and stir the cement, aggregate, silica ash, fly ash, water and composite air entraining agent, then add polypropylene fiber and continue stirring until uniform;

[0041] S4. Molding and curing: pour the prepared slurry into a mold for molding and curing for 28 days.

[0042] Comparative example 1

[0043] A cement-based grouting material, basically the same as example 1, the only difference is that the type of composite air entraining agent is different, using conventional air entraining agent (rosin hot polymer), the result is low fluidity, poor frost resistance (large mass loss under freeze-thaw cycle).

[0044] Comparative example 2

[0045] A cement-based grouting material, basically the same as example 1, the only difference is that no nano aluminum oxide is added, the slurry has the problems of reduced compressive strength and high expansion rate, the expansion rate reflects stability and durability, and slight expansion is best.

[0046] Comparative example 3

[0047] A cement-based grouting material, basically the same as example 1, the only difference is that no polypropylene fiber is added, the slurry has the problems of poor crack resistance and stability (linear shrinkage rate increases significantly).

[0048] The slurries of the above examples and comparative examples were tested for performance, and the test results are shown in the following table:

[0049]

[0050] Note: The mass loss and linear shrinkage in the table are measured under the condition of 200 freeze-thaw cycles.

[0051] From the above table, the anti-freezing grouting material of the application has significant advantages in compressive strength, freeze-thaw durability, construction fluidity and dimensional stability, etc., and has lower preparation cost, and has good market application prospect.

[0052] The specific embodiment is only an explanation of the application, and is not a limitation of the application, and any change made by a person skilled in the art after reading the specification of the application will be protected by the patent law as long as it is within the scope of the claims of the application.

Claims

1. A high-durability antifreeze composite grouting material, characterized in that: The invention comprises the following components: cement, silica fume, fly ash, aggregate, water, composite air entraining agent, polypropylene fiber and admixture; the aggregate is quartz sand, the composite air entraining agent comprises modified polycarboxylate and nano aerogel, and the admixture comprises water reducing agent and nano alumina.

2. The high-durability antifreeze composite grouting material according to claim 1, characterized in that: The composition comprises, by weight, 55-65 parts of cement, 5-15 parts of silica fume, 10-20 parts of fly ash, 25-35 parts of aggregate, 15-20 parts of water, 0.1-0.2 parts of composite air-entraining agent, 0.2-0.4 parts of polypropylene fiber, 0.5-1.5 parts of water reducer, and 1-2 parts of nano-alumina. The composite air-entraining agent is prepared by compounding modified polycarboxylate and nano-aerogel in a mass ratio of (3-5):

1. The length of the polypropylene fiber is 6-10 mm.

3. The high-durability antifreeze composite grouting material according to claim 2, characterized in that: The composition comprises, by weight, 60 parts of cement, 10 parts of silica fume, 15 parts of fly ash, 30 parts of aggregate, 18 parts of water, 0.1 parts of composite air-entraining agent, 0.3 parts of polypropylene fiber, 1 part of water reducer, and 1.5 parts of nano-alumina; the composite air-entraining agent is a compound of modified polycarboxylate and nano-aerogel in a mass ratio of 4:1, and the length of the polypropylene fiber is 6 mm.

4. The high-durability antifreeze composite grouting material according to claim 1, characterized in that: The cement is P.O52.5R Portland cement, and the C3A content is controlled to be 5-8%.

5. The high-durability antifreeze composite grouting material according to claim 1, characterized in that: The aggregate is graded quartz sand with a particle size of 0.1-1.2 mm.

6. The high-durability antifreeze composite grouting material according to claim 1, characterized in that: The SiO2 content of the silica fume is greater than 70%.

7. The high-durability antifreeze composite grouting material according to claim 1, characterized in that: The water reducer is a polycarboxylic acid water reducer with a water reduction rate greater than 15%, a molecular weight of 8000-12000, a side chain density of 25-30%, and a copolymerization of phosphoric acid groups and carboxylic acid groups.

8. The method for preparing the high-durability antifreeze composite grouting material according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Raw material preparation: Weigh cement, aggregate, silica fume, fly ash, water, and admixtures; S2. Preparation of composite air-entraining agent: Mix multiple air-entraining agents in proportion to prepare a composite air-entraining agent; S3 slurry preparation: cement, aggregate, silica fume, fly ash, water and composite air-entraining agent are mixed and stirred, followed by addition of polypropylene fiber, and continued stirring until uniform; S4. Molding and curing: The prepared slurry is injected into a mold for molding and cured for 28 days.

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