High-performance cement adhesive and preparation method thereof

Abstract

The invention discloses a high-performance cement adhesive and a preparation method thereof, and belongs to the technical field of cement adhesives, the cement adhesive comprises 100 parts of cement, 80-150 parts of river sand, 20-30 parts of water, 3-10 parts of an expanding agent, 5-15 parts of silica powder, 2-7 parts of wollastonite fiber, 0.1-0.4 part of a defoaming agent, and 1-2.5 parts of a water reducing agent. By introducing the wollastonite fiber, the core mechanical property of the cement adhesive can be obviously optimized, and the crack initiation and instability toughness, fracture resistance and compressive strength of the cement adhesive are greatly improved. The optimal grading of the sand is determined by adopting a closest packing method, and the water-cement ratio and the cement-sand ratio are further optimized, so that the number of abnormal pores and cracks in the adhesive can be effectively reduced, the internal microstructure and compactness of the adhesive are remarkably improved, and the risk of local stress concentration is reduced. Through the controllable expansion effect generated by the expanding agent, dry shrinkage and self-shrinkage generated in the cement hardening process are accurately compensated, and the internal stress concentration phenomenon caused by unbalanced shrinkage is effectively relieved.

Description

Technical Field

[0001] This invention relates to the field of cement adhesives for porcelain insulators, specifically to a high-performance cement adhesive and its preparation method. Background Technology

[0002] In power transmission, insulators are crucial components ensuring the safe and reliable operation of the power grid. Damage to insulators can lead to line breaks or disconnections, jeopardizing grid safety. Ultra-high voltage (UHV) transmission projects, due to their high voltage, high current, and strong electric fields, place even higher demands on insulator performance. The structure of porcelain insulators consists of porcelain components, cement adhesive, and fittings (metal accessories). While the porcelain components and fittings possess high mechanical strength, the cement adhesive, as the core connector, has relatively low strength and toughness, forming a weak point in the structure and potentially causing safety hazards.

[0003] In cementitious adhesives, the generation of air bubbles is mainly due to the high surface activity of raw material powders, which carries gas molecules, the air-entraining effect of additives, etc.; high temperature in the environment accelerates the evaporation of moisture, causing air bubbles to form on the surface, while low temperature causes air bubbles to shrink, leaving pores inside; and the stirring process during preparation causes air bubbles to form and vibrate, resulting in air bubbles not being completely eliminated or air bubbles reorganizing and becoming larger.

[0004] Cracks can also easily form in cement adhesives. Improper use of water or water-reducing agents during the preparation process can also increase the risk of cracking. External forces such as wind vibration and mechanical loads during operation subject cement adhesives to repeated stress, which may cause micro-cracks over a long period of time. At the same time, rainwater infiltration can cause corrosive expansion of cement stone, which can exacerbate crack propagation.

[0005] Based on this, the present invention designs a high-performance cementitious adhesive with high strength, high toughness, high crack resistance, and high volume stability to solve the above problems. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the existing technology, the present invention provides a high-performance cement adhesive and its preparation method.

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

[0008] A high-performance cementitious adhesive comprises the following components by weight:

[0009] 100 parts silicate cement, 80-150 parts river sand, 20-30 parts water, 3-10 parts CSA expanding agent, 5-15 parts silica powder, 2-7 parts wollastonite fiber, 0.1-0.4 parts fatty alcohol polyether defoamer, and 1-2.5 parts polycarboxylate superplasticizer.

[0010] Furthermore, the river sand is composed of 30-70 mesh sand and 60-120 mesh sand in a mass ratio of 1.7-2.3:1.

[0011] Furthermore, the CSA expanding agent is a mixture of anhydrous calcium sulfoaluminate and calcium oxide.

[0012] A method for preparing the high-performance cementitious adhesive, characterized by comprising the following steps:

[0013] S1: Raw material pretreatment, mixing polycarboxylate superplasticizer with deionized water at 5-10℃ to prepare a 20-30wt% superplasticizer solution;

[0014] S2: Dry material mixing: Weigh silicate cement, river sand, CSA expanding agent, silica powder, wollastonite fiber, and fatty alcohol polyether defoamer, and stir at 73-78 r / min for 2-5 min;

[0015] S3: Wet mixing, add water, stir at 109-114 r / min for 2-5 min, first add 80-90% of the total amount of water-reducing agent solution, and continue stirring for 2-5 min;

[0016] S4: Fine stirring, stir for 6-8 minutes at a speed of 143-148 r / min, add the remaining 10-20% water-reducing agent solution until the flow value reaches 250-300 mm;

[0017] S5: Discharge the material. After mixing for 12-23 minutes, discharge the material to obtain a high-performance cementitious adhesive.

[0018] S6: Curing, raise the temperature from room temperature to 42-57℃ within 30 minutes, with a relative humidity of not less than 90%, and keep warm for 5.0-6.5 hours.

[0019] Compared with the prior art, the beneficial effects of this invention are as follows:

[0020] 1. This invention improves the bonding between the added inorganic mineral wollastonite microfibers and the hydration products of silicate cement, thus enhancing the adhesion between the fibers and the interface. Furthermore, when the adhesive is damaged, it must overcome its own cohesive force, the frictional force between the wollastonite fibers and the interface, and the cohesive force required for the wollastonite fibers to fracture. These combined forces effectively improve the mechanical properties of the adhesive. The needle-like structure of the wollastonite fibers, interlocking to form a three-dimensional reinforcing network, inhibits the generation and propagation of microcracks, improves instability toughness, and mitigates brittleness. Compared to traditional organic PP fibers, inorganic wollastonite fibers significantly optimize the core mechanical properties of cement adhesives, greatly improving their flexural strength, compressive strength, toughness, and crack initiation toughness. This ensures that the adhesive is no longer a mechanical weakness in the porcelain insulator structure system, synergistically complementing the high-strength characteristics of porcelain components and fittings. This effectively enhances the load-bearing capacity and impact resistance of the entire insulator structure, providing stable support for the insulator to withstand various loads during long-term power grid operation.

[0021] 2. This invention uses polyether fatty alcohol as a defoamer, which belongs to the nonionic surfactant category. Its structure typically consists of two parts: a hydrophobic end (fatty alcohol chain) and a hydrophilic end (polyether segment). This hydrophilic-hydrophobic structure gives it excellent surface activity and interface regulation capabilities. Through its surface activity, the polyether fatty alcohol can rapidly destroy pores in the cement paste, effectively reducing the number of abnormal pores generated within the adhesive, significantly improving the density of the adhesive's internal microstructure, reducing the risk of localized stress concentration caused by pores, and simultaneously enhancing the adhesive's impermeability and resistance to environmental erosion. This prevents external moisture and corrosive media from penetrating the interior through pores and causing performance degradation, thus extending the adhesive's service life.

[0022] 3. This invention utilizes the controllable expansion effect produced by the synergistic effect of anhydrous calcium sulfoaluminate and calcium oxide in the CSA expanding agent. Specifically, anhydrous calcium sulfoaluminate reacts with cement hydration products to generate ettringite (expandable crystals), and calcium oxide reacts with water to generate calcium hydroxide (accompanied by volume expansion). This expansion can precisely compensate for the drying shrinkage and autogenous shrinkage generated during cement hardening, making the internal stress distribution of the adhesive more uniform and effectively alleviating the internal stress concentration phenomenon caused by uneven shrinkage. It can not only reduce the generation of new microcracks, but also inhibit the expansion of existing microcracks, further ensuring the structural integrity of the adhesive. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0024] Figure 1 This is a microscopic morphology diagram of wollastonite fibers;

[0025] Figure 2 The graph shows the changes in compressive and flexural strength of the cementitious adhesives prepared in the comparative example and Example 3.

[0026] Figure 3 The image shows the pore morphology of the cementitious adhesive prepared in the comparative example.

[0027] Figure 4 The image shows the pore morphology of the cementitious adhesive prepared in Example 3.

[0028] Figure 5 This is a microscopic morphology diagram of wollastonite fibers in cementitious binders. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] Example 1: This example provides a method for preparing a high-performance cementitious adhesive, including the following steps:

[0031] Weigh the raw materials: 100 parts of P·II 52.5R silicate cement, 150 parts of river sand, 30 parts of water, 10 parts of CSA expansion agent, 15 parts of silica powder, 7 parts of wollastonite fiber, 0.4 parts of fatty alcohol polyether defoamer, and 2.5 parts of polycarboxylate superplasticizer.

[0032] The river sand is composed of 30-70 mesh sand and 60-120 mesh sand in a mass ratio of 2.3:1.

[0033] The CSA expanding agent is a mixture of anhydrous calcium sulfoaluminate and calcium oxide in a molar ratio of 1:1.

[0034] S1: Raw material pretreatment: Polycarboxylate superplasticizer is mixed with 10℃ deionized water to prepare a 30wt% superplasticizer solution;

[0035] S2: Dry material mixing: Weigh silicate cement, river sand, CSA expansion agent, silica powder, wollastonite fiber, and fatty alcohol polyether defoamer, and stir at 78 r / min for 5 min;

[0036] S3: Wet mixing, add water, stir at 114 r / min for 5 min, add 90% of the total amount of water-reducing agent solution, and continue stirring for 5 min;

[0037] S4: Fine stirring, stir for 8 minutes at a speed of 148 r / min, add the remaining 20% ​​water-reducing agent solution until the flow value reaches 300 mm;

[0038] S5: Discharge. After stirring for 23 minutes, discharge to obtain a high-strength, high-toughness, and low-shrinkage cementitious adhesive.

[0039] S6: Curing, rapid steam curing, raising the product from room temperature to 49°C in 28 minutes, with relative humidity not lower than 90%, and heat preservation time of 5.5 hours.

[0040] Example 2: This example provides a method for preparing a high-performance cementitious adhesive, including the following steps:

[0041] Weigh the raw materials: 100 parts silicate cement, 80 parts river sand, 20 parts water, 3 parts CSA expansion agent, 5 parts silica powder, 2 parts wollastonite fiber, 0.1 parts fatty alcohol polyether defoamer, and 1 part polycarboxylate superplasticizer.

[0042] The river sand is composed of 30-70 mesh sand and 60-120 mesh sand in a mass ratio of 1.7:1.

[0043] The CSA expanding agent is a mixture of anhydrous calcium sulfoaluminate and calcium oxide in a molar ratio of 1:1.

[0044] S1: Raw material pretreatment: Polycarboxylate superplasticizer is mixed with 5℃ deionized water to prepare a 20wt% superplasticizer solution;

[0045] S2: Dry material mixing: Weigh silicate cement, river sand, CSA expansion agent, silica powder, wollastonite fiber, and fatty alcohol polyether defoamer, and stir at 73 r / min for 2 min;

[0046] S3: Wet mixing, add water, stir at 109 r / min for 2 min, first add 80% of the total amount of water-reducing agent solution, and continue stirring for 2 min;

[0047] S4: Fine stirring, stir for 6 minutes at 143 r / min, add the remaining 10% water-reducing agent solution until the flow value reaches 250 mm;

[0048] S5: Discharge. After stirring for 12 minutes, discharge to obtain ultra-high performance cementitious adhesive.

[0049] S6: Curing, raise the product from room temperature to 57°C in 30 minutes, with relative humidity not lower than 90%, and keep it warm for 6.5 hours.

[0050] Example 3: This example provides a method for preparing a high-performance cementitious adhesive, including the following steps:

[0051] Weigh the raw materials: 100 parts silicate cement, 122 parts river sand, 25 parts water, 6 parts CSA expansion agent, 10 parts silica powder, 4 parts wollastonite fiber, 0.26 parts fatty alcohol polyether defoamer, and 1.8 parts polycarboxylate superplasticizer.

[0052] The river sand is composed of 30-70 mesh sand and 60-120 mesh sand in a mass ratio of 1.9:1.

[0053] The CSA expanding agent is a mixture of anhydrous calcium sulfoaluminate and calcium oxide in a molar ratio of 1:1.

[0054] S1: Raw material pretreatment: Polycarboxylate superplasticizer is mixed with deionized water at 8°C to prepare a 28wt% superplasticizer solution;

[0055] S2: Dry material mixing: Weigh silicate cement, river sand, CSA expansion agent, silica powder, wollastonite fiber, and fatty alcohol polyether defoamer, and stir at 75 r / min for 3 min;

[0056] S3: Wet mixing, add water, stir at 112 r / min for 4 min, first add 84% of the total amount of water-reducing agent solution, and continue stirring for 4 min;

[0057] S4: Fine stirring, stir for 7 minutes at 146 r / min, add the remaining 16% water-reducing agent solution until the flow value reaches 270 mm;

[0058] S5: Discharge. After mixing for 18 minutes, discharge to obtain a high-performance cementitious adhesive.

[0059] S6: Curing, rapid steam curing, raising the product from room temperature to 42°C in 25 minutes, with relative humidity not lower than 90%, and holding for 5.0 hours.

[0060] Comparative Example: The difference between this comparative example and Example 3 is that the raw material ratio is different: raw materials: 100 parts silicate cement, 40 parts river sand (30-70 mesh), 34 parts water, 6 parts CSA expansion agent, 10 parts silica powder, 0.2 parts PP fiber, and 0.6 parts naphthalene-based water-reducing agent.

[0061] According to JB / T 4307-2004 "Cement Adhesive for Insulator Installation", the cement adhesives prepared in the examples and comparative examples were tested for compressive and flexural strength, drying shrinkage, autoclaving expansion and fracture toughness.

[0062] The method for detecting pore morphology involves photographing the cross-section of the specimen using an optical microscope to obtain high-resolution cross-sectional images. Then, the pores in the cross-sectional images are binarized using ImagePro software, and statistical calculations are performed (e.g.,...). Figure 3-4 (As shown). The microstructure detection method involves using a scanning electron microscope to photograph the cross-sectional area of ​​the specimen to obtain microstructure images of wollastonite fibers achieving micro-reinforcement and toughening in cementitious adhesives (e.g., Figure 5 (As shown).

[0063] The results are shown in the table below:

[0064]

[0065]

[0066] As shown in the table above, by adding inorganic mineral wollastonite microfibers, such as Figure 1 As shown, by using the most compact packing method for the gradation of two sands with different particle sizes, adjusting the water-cement ratio and sand-cement ratio, and adding an expanding agent and a fatty alcohol polyether defoamer, the mechanical properties of the cementitious adhesive were significantly improved, such as... Figure 2 As shown (comparative example to Example 3), the 7-day flexural strength of Example 3 increased by approximately 38.5%, and the 11-day and 28-day flexural strengths increased by approximately 58.9% and 52.4%, respectively; the 7-day, 11-day, and 28-day compressive strengths increased by approximately 23.7%, 23.9%, and 34.3%, respectively; the autoclaving expansion rate decreased by approximately 55.0%; the 7-day and 11-day shrinkage rates decreased by approximately 73.1% and 65.2%, respectively; the fracture toughness increased by approximately 35%; and the number of abnormal pores decreased significantly (e.g., ...). Figure 3-4 As shown); at the microscopic level, wollastonite fibers significantly bridge cracks and fill the matrix, effectively strengthening and toughening the cementitious adhesive (as shown). Figure 5 (As shown).

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-performance cementitious adhesive, characterized in that, The following components are included by mass parts: 100 parts silicate cement, 80-150 parts river sand, 20-30 parts water, 3-10 parts CSA expanding agent, 5-15 parts silica powder, 2-7 parts wollastonite fiber, 0.1-0.4 parts fatty alcohol polyether defoamer, and 1-2.5 parts polycarboxylate superplasticizer.

2. The high-performance cementitious adhesive according to claim 1, characterized in that, The river sand is composed of 30-70 mesh sand and 60-120 mesh sand in a mass ratio of 1.7-2.3:

1.

3. The high-performance cementitious adhesive according to claim 1, characterized in that, The CSA expanding agent is a mixture of anhydrous calcium sulfoaluminate and calcium oxide.

4. A method for preparing a high-performance cementitious adhesive as described in any one of claims 1-3, characterized in that, Includes the following steps: S1: Raw material pretreatment, mixing polycarboxylate superplasticizer with deionized water at 5-10℃ to prepare a 20-30wt% superplasticizer solution; S2: Dry material mixing: Weigh silicate cement, river sand, CSA expansion agent, silica powder, wollastonite fiber, and fatty alcohol polyether defoamer, and stir at 73-78 r / min for 2-5 min; S3: Wet mixing, add water, stir at 109-114 r / min for 2-5 min, first add 80-90% of the total amount of water-reducing agent solution, and continue stirring for 2-5 min; S4: Fine stirring, stir for 6-8 minutes at a speed of 143-148 r / min, add the remaining 10-20% water-reducing agent solution until the flow value reaches 250-300 mm; S5: Discharge the material. After mixing for 12-23 minutes, discharge the material to obtain an ultra-high performance cementitious adhesive. S6: Curing, raise the temperature from room temperature to 42-57℃ within 30 minutes, with a relative humidity of not less than 90%, and keep warm for 5.0-6.5 hours.

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