Early strength polymer modified cement-based grouting material and preparation method thereof

Abstract

The invention belongs to the technical field of building materials, and discloses an early-strength polymer modified cement-based grouting material and a preparation method thereof. The grouting material disclosed by the invention is prepared from the following raw materials in parts by weight: 100 to 115 parts of a cementing material, 100 to 115 parts of river sand, 20 to 23 parts of water, 2 to 2.5 parts of a water reducing agent, 0.02 to 0.04 part of an expanding agent, 0.22 to 1.76 parts of an acrylic emulsion and 0.04 to 0.08 part of a de-foaming agent, wherein the cementing material comprises 71-81 parts of Portland cement, 9-19 parts of sulphoaluminate cement, 6-8 parts of silica fume and 11-15 parts of fly ash microbeads. The early-strength, high-strength and high-fluidity cement-based grouting material can be obtained under the conventional curing condition by adopting the combined action of the acrylic emulsion polymer, the Portland cement and the sulphoaluminate cement, the plastic expanding agent, the polycarboxylate superplasticizer and the defoaming agent, and has good economic benefits and practical values.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to an early-strength polymer-modified cement-based grouting material and a preparation method thereof. Background Art

[0002] With the rise of prefabricated buildings and offshore wind power, grouting materials play a crucial connecting role, which makes the performance requirements of cement-based grouting materials continuously increasing. However, in actual use, cement-based grouting materials usually have difficulty in balancing fluidity and compressive strength. Generally, cement-based grouting materials with high fluidity lack coarse aggregates, have low compressive strength, and will cause large shrinkage resulting in cracking, posing significant potential safety hazards at grouting joints and other problems. While cement-based grouting materials with high compressive strength have poor fluidity and short operable time, which is not conducive to the construction progress. Therefore, it is of great significance to develop a grouting material with early strength, high strength, high fluidity and low shrinkage.

[0003] In current research, external addition of fibers such as basalt fibers, steel fibers, PVA fibers, etc. is mostly used to achieve the purpose of improving its strength and reducing shrinkage, but it will significantly reduce the fluidity of the grouting material, and the relatively high price of the fibers makes it difficult to reduce the overall cost of the grouting material. The present invention prepares a high-strength cement-based grouting material by adding polymer modification. Summary of the Invention

[0004] In order to overcome the above-mentioned disadvantages and deficiencies of the prior art, the primary object of the present invention is to provide an early-strength polymer-modified cement-based grouting material.

[0005] Another object of the present invention is to provide a preparation method of the above-mentioned early-strength polymer-modified cement-based grouting material.

[0006] The object of the present invention is achieved by the following solutions:

[0007] An early-strength polymer-modified cement-based grouting material, comprising the following raw materials in parts by weight: 100-115 parts of cementitious material, 100-115 parts of river sand, 20-23 parts of water, 2-2.5 parts of water reducer, 0.02-0.04 parts of expansive agent, 0.22-1.76 parts of acrylic emulsion, 0.04-0.08 parts of defoamer; wherein, the cementitious material comprises 71-81 parts of portland cement, 9-19 parts of sulfoaluminate cement, 6-8 parts of silica fume, and 11-15 parts of fly ash cenosphere.

[0008] The particle size of the river sand is less than 5 mm.

[0009] The specific surface area of the silica fume is 15-27 m 2 / g, the mass content of silicon dioxide is 90%-96%, and its mass accounts for 5%-7% of the mass of the cementitious material.

[0010] The density of the fly ash microspheres is 1.9 - 2.5 g / cm 3 , the loss on ignition is 0.7 - 1.0%, the strength activity index is 85%, and its mass accounts for 10 - 14% of the mass of the cementitious material.

[0011] The water reducing agent is a polycarboxylate water reducing agent, with a water reducing rate of 30 - 32%, a solid content of 32 - 34%, an average particle size of 0.1 - 0.15 μm, an air content of 3.0%, and a dosage of 1.8 - 2.2% of the mass of the cementitious material.

[0012] The expansive agent is a plastic expansive agent, with a yellow powder appearance and a bulk density of 300 - 600 kg / m 3 , and the mass content of chloride ions ≤ 0.05%.

[0013] The solid content of the acrylic emulsion is 37%, the viscosity is 1200 - 1600 cps, and the dosage is 0.2% - 1.6% of the mass of the cementitious material.

[0014] The defoaming agent is tributyl phosphate, and the dosage is 2 - 4% of the mass of the water reducing agent.

[0015] The early strength polymer modified cementitious grouting material comprises the following raw materials in parts by weight: 109 - 110 parts of cementitious material, 110 parts of river sand, 21.1 - 22 parts of water, 2.2 parts of water reducing agent, 0.02 parts of expansive agent, 0.44 - 1.32 parts of acrylic emulsion, 0.06 parts of defoaming agent; among them, the cementitious material includes 71 - 81 parts of portland cement, 9 - 19 parts of sulphoaluminate cement, 6.8 parts of silica fume, and 13 parts of fly ash microspheres.

[0016] The preparation method of the above early strength polymer modified cementitious grouting material comprises the following steps:

[0017] (1) Weigh portland cement, sulphoaluminate cement, river sand, silica fume, and fly ash microspheres according to the formula, and mix and stir for 3 - 4 minutes;

[0018] (2) Weigh water, water reducing agent, expansive agent, acrylic emulsion, and defoaming agent, mix them evenly and then add them to the slurry obtained in step (1), and stir for 4 - 5 minutes to obtain the early strength polymer modified cementitious grouting material.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] 1. The early-strength polymer-modified cement-based grouting material provided by the present invention, compared with the existing grouting materials, is added with an appropriate amount of acrylic emulsion polymer modification. The cement particles can be wrapped by the acrylic polymer, which can not only enhance its ball bearing effect and improve its fluidity to a certain extent, but also delay the rapid setting of the compound admixture of sulfoaluminate cement and ordinary Portland cement to a certain extent, so as to achieve the purpose of controllable setting time. The main cementitious material of the present invention is ordinary Portland cement, and then sulfoaluminate cement with its own micro-expansion performance is incorporated, and a small amount of plastic expansion agent is supplemented to compensate for the shrinkage during the early hydration process of the grouting material. The prepared grouting material can achieve a relatively high early strength on the premise of ensuring quick setting. Under the combined action of the acrylic polymer and the sulfoaluminate cement, the shrinkage of the grouting material can be effectively reduced while maintaining a relatively high fluidity and strength.

[0021] 2. The early-strength polymer-modified cement-based grouting material provided by the present invention can achieve the purpose of early strength and high strength. Its compressive strength can reach 50.4 - 57.0 Mpa at 1 day and 92.1 - 107.6 Mpa at 28 days, and the strength at 1 day can reach more than 50% of the strength at 28 days. Moreover, it has a high fluidity, and the fluidity out of the mixer can reach 320.5 mm - 353.3 mm. It can be used directly at the construction site only after stirring, and can achieve self-leveling without vibration.

[0022] 3. The early-strength polymer-modified cement-based grouting material provided by the present invention adds a relatively large amount of silica fume and fly ash microspheres (accounting for 18% of the mass of the cementitious material), which can reduce the usage amount of cement, achieve the purpose of reducing carbon emissions, and the preparation method is simple to operate. It can ensure a certain operation time while achieving quick setting, has low technical requirements for operators, and is easy to implement, popularize and apply. Description of the Drawings

[0023] Figure 1 Dry shrinkage rates of the grouting materials obtained in Examples 1 - 4 and Comparative Examples 1 - 2. Detailed Embodiments

[0024] The present invention will be further described in detail below in conjunction with the embodiments and the drawings, but the embodiments of the present invention are not limited thereto. For those not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0025] The reagents used in the embodiments can be conventionally purchased from the market without special instructions.

[0026] River sand: particle size less than 5 mm;

[0027] Silica fume: specific surface area 22 m 2 / g, silicon dioxide mass content is 94%;

[0028] Fly ash microspheres: density is 2.0 g / cm 3 , loss on ignition is 0.9%, and strength activity index is 85%;

[0029] Polycarboxylate water reducer: water reducing rate is 31%, solid content is 34.24%, average particle size is 0.12 μm, and air content is 3.0%;

[0030] Plastic expansion agent: appearance is yellow powder, bulk density is 500 kg / m 3 , chloride ion mass content is 0.03%;

[0031] Acrylic emulsion: solid content is 37%, viscosity is 1300 cps.

[0032] In the following examples and comparative examples, 1 part = 10 kg.

[0033] Example 1

[0034] (1) Weigh 81 parts of portland cement, 9 parts of sulfoaluminate cement, 110 parts of river sand, 6.8 parts of silica fume, and 13 parts of fly ash microspheres, add them to a mortar mixer, and start stirring simultaneously. The stirring time is 3 minutes;

[0035] (2) Weigh 22 parts of water, 2.2 parts of polycarboxylate water reducer, 0.02 part of plastic expansion agent, 0.44 part of acrylic emulsion, and 0.06 part of tributyl phosphate, stir and mix them evenly, then add them to the mortar mixer. The stirring time is 4 minutes to obtain an early-strength polymer-modified cement-based grouting material.

[0036] Example 2

[0037] (1) Weigh 81 parts of portland cement, 9 parts of sulfoaluminate cement, 110 parts of river sand, 6.8 parts of silica fume, and 13 parts of fly ash microspheres, add them to a mortar mixer, and start stirring simultaneously. The stirring time is 3 minutes;

[0038] (2) Weigh 21.5 parts of water, 2.2 parts of polycarboxylate water reducer, 0.02 part of plastic expansion agent, 0.88 part of acrylic emulsion, and 0.06 part of tributyl phosphate, stir and mix them evenly, then add them to the mortar mixer. The stirring time is 4 minutes to obtain an early-strength polymer-modified cement-based grouting material.

[0039] Example 3

[0040] (1) Weigh 81 parts of portland cement, 9 parts of sulfoaluminate cement, 110 parts of river sand, 6.8 parts of silica fume, and 13 parts of polycarboxylate water reducer, add them to a mortar mixer, and start stirring simultaneously. The stirring time is 3 minutes;

[0041] (2) Weigh 21.1 parts of water, 2.2 parts of polycarboxylate water reducer, 0.02 parts of plastic expansion agent, 1.32 parts of acrylic emulsion, and 0.06 parts of tributyl phosphate. After stirring and mixing evenly, add them to a mortar mixer and stir for 4 minutes to obtain an early-strength polymer-modified cement-based grouting material.

[0042] Example 4

[0043] (1) Weigh 71 parts of portland cement, 19 parts of sulfoaluminate cement, 110 parts of river sand, 6.8 parts of silica fume, and 13 parts of polycarboxylate water reducer, add them to a mortar mixer, and start stirring simultaneously. The stirring time is 3 minutes;

[0044] (2) Weigh 22 parts of water, 2.2 parts of polycarboxylate water reducer, 0.02 parts of plastic expansion agent, 0.44 parts of acrylic emulsion, and 0.06 parts of tributyl phosphate. After stirring and mixing evenly, add them to a mortar mixer and stir for 4 minutes to obtain an early-strength polymer-modified cement-based grouting material.

[0045] Comparative Example 1

[0046] (1) Weigh 89 parts of existing high-strength steel fiber cement grouting material and add it to a mortar mixer, and start stirring simultaneously. The stirring time is 3 minutes

[0047] (2) Weigh 11 parts of water into the mortar mixer and stir for 4 minutes to obtain a steel fiber cement-based grouting material.

[0048] Comparative Example 2

[0049] Different from Examples 1 - 4, sulfoaluminate cement and acrylic emulsion were not added.

[0050] (1) Weigh 90 parts of portland cement, 110 parts of river sand, 6.8 parts of silica fume, and 13 parts of fly ash cenospheres, add them to a mortar mixer, and start stirring simultaneously. The stirring time is 3 minutes

[0051] (2) Weigh 22 parts of water, 2.2 parts of polycarboxylate water reducer, 0.06 parts of tributyl phosphate, and 0.02 parts of plastic expansion agent. After stirring and mixing evenly, add them to a mortar mixer and stir for 4 minutes to obtain an unmodified cement-based grouting material.

[0052] In accordance with the standard JGT 408 - 2013 "Grouting Sleeves for Steel Bar Connection", relevant performance indicators of the grouting materials obtained in Examples 1 - 4 and Comparative Examples 1 - 2 were tested. Among them, the compressive strength and flexural strength were tested on the set test blocks (prepared by pouring the materials obtained in Examples 1 - 4 and Comparative Examples 1 - 2 into molds and demolding after 24 hours). The performance of the grouting materials is shown in Table 1, and the dry shrinkage rate is as Figure 1 shown.

[0053] Table 1

[0054]

[0055]

[0056] From the test data of Example 1, Example 2, Example 3, and Comparative Example 1, it can be seen that after the dosage of acrylic emulsion is increased, the initial setting time and final setting time of the grouting material are both extended, indicating that it can effectively delay the rapid setting phenomenon caused by the compounding of portland cement and sulfoaluminate cement, giving sufficient operation time at the construction site. The flexural strength and early compressive strength increase with the increase of its dosage, and the fluidity and 28d compressive strength reach the highest when 0.88 parts of acrylic emulsion are incorporated. The dry shrinkage rate decreases with the increase of acrylic emulsion, and acrylic emulsion is beneficial to reducing the shrinkage of the grouting material.

[0057] From the test data of Example 1, Example 4, Comparative Example 1, and Comparative Example 2, it can be seen that as the dosage of sulfoaluminate cement increases, the setting time of the grouting material shortens accordingly, the flexural strength and early strength increase, and the 28d compressive strength decreases slightly. The dry shrinkage rate decreases with the increase of the dosage of sulfoaluminate cement, and sulfoaluminate cement can effectively reduce the shrinkage of the grouting material.

[0058] Based on the above results, it can be known that the polymer-modified cement-based grouting material can obtain better early and late strengths, and at the same time it has better fluidity and low shrinkage effect.

[0059] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. An early strength polymer modified cement-based grouting material, characterized in that: The method comprises the following raw materials in parts by weight: 100-115 parts of cementitious materials, 100-115 parts of river sand, 20-23 parts of water, 2-2.5 parts of water reducing agent, 0.02-0.04 parts of expansion agent, 0.22-1.76 parts of acrylic emulsion and 0.04-0.08 parts of defoaming agent; wherein the cementitious materials comprise 71-81 parts of silicate cement, 9-19 parts of sulphoaluminate cement, 6-8 parts of silica fume and 11-15 parts of fly ash microbeads.

2. The early strength polymer modified cement-based grouting material according to claim 1, characterized in that: The particle size of the river sand is less than 5 mm.

3. The early strength polymer modified cement-based grouting material according to claim 1, characterized in that: The specific surface area of ​​the silica fume is 15 to 27 m 2 / g, the mass content of silicon dioxide is 90% to 96%, and its mass accounts for 5 to 7% of the mass of the cementitious material.

4. The early strength polymer modified cement-based grouting material according to claim 1, characterized in that: The density of the fly ash microspheres is 1.9-2.5 g / cm 3 The loss on ignition is 0.7-1.0%, the strength activity index is 85%, and its mass accounts for 10-14% of the mass of the cementitious material.

5. The early strength polymer modified cement-based grouting material according to claim 1, characterized in that: The water reducing agent is a polycarboxylic acid water reducing agent, with a water reducing rate of 30-32%, a solid content of 32-34%, an average particle size of 0.1-0.15 μm, an air content of 3.0%, and a dosage of 1.8-2.2% of the mass of the cementitious material.

6. The early strength polymer modified cement-based grouting material according to claim 1, characterized in that: The expansion agent is a plastic expansion agent, which is yellow powder in appearance and has a bulk density of 300-600 kg / m 3 , chloride ion mass content ≤0.05%.

7. The early strength polymer modified cement-based grouting material according to claim 1, characterized in that: The acrylic emulsion has a solid content of 37%, a viscosity of 1200-1600 cps, and a dosage of 0.2% to 1.6% of the mass of the gelling material.

8. The early strength polymer modified cement-based grouting material according to claim 1, characterized in that: The defoaming agent is tributyl phosphate, and the dosage is 2-4% of the mass of the water reducing agent.

9. The early strength polymer modified cement-based grouting material according to claim 1, characterized in that: It includes the following raw materials in parts by weight: 109-110 parts of cementitious materials, 110 parts of river sand, 21.1-22 parts of water, 2.2 parts of water reducing agent, 0.02 parts of expansion agent, 0.44-1.32 parts of acrylic emulsion, and 0.06 parts of defoaming agent; wherein, the cementitious materials include 71-81 parts of silicate cement, 9-19 parts of sulphoaluminate cement, 6.8 parts of silica fume, and 13 parts of fly ash microbeads.

10. The method for preparing the early strength polymer modified cement-based grouting material according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Weigh silicate cement, sulphoaluminate cement, river sand, silica fume and fly ash microspheres according to the formula, mix and stir for 3 to 4 minutes; (2) Weigh water, a water reducing agent, an expansion agent, an acrylic emulsion, and a defoaming agent, mix them evenly, and then add them to the slurry obtained in step (1), and stir for 4 to 5 minutes to obtain an early strength polymer modified cement-based grouting material.

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