Alkali-activated mk-bfs inorganic adhesive and preparation method and application thereof

Abstract

The application discloses a kind of alkali-activated MK-BFS inorganic glue and its preparation method and application, belong to the technical field of inorganic glue modification, including solid component and liquid component, the solid component includes 18.6~20 portions MK, 74.4~80 portions BFS and 0.3~7 portions interface modification material;The liquid component includes alkaline activator and water;The alkaline activator is the compounded solution obtained by mixing NaOH and water glass solution;The interface modification material is selected from one or several of nano-SiO2, nano-Al2O3, wollastonite whisker and PVA fiber.The application utilizes the interface modification material to carry out bonding modification to alkali-activated MK-BFS inorganic glue, and is better to improve FRP-concrete interface bonding performance from amorphous area regulation and control and interface densification, surface effect and chemical bonding, ion migration and reaction promotion, physical filling and mechanical interlocking, induced adsorption nucleation and crack bridging etc.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of inorganic glue modification, and particularly relates to an alkali-activated MK-BFS inorganic glue and a preparation method and application thereof. BACKGROUND

[0002] With the increase of infrastructure service life, the demand for engineering structure reinforcement is increasingly prominent. In recent years, fiber reinforced polymer (FRP) and FRP reinforcement technology have become a research hotspot in the field of engineering reinforcement due to their excellent characteristics such as light weight, high strength, convenient construction, corrosion resistance, etc. At present, epoxy resin-based adhesives are still the mainstream of FRP-based reinforcement, and their good bonding strength and process adaptability effectively guarantee the structure reinforcement effect. However, such organic adhesives are prone to performance degradation such as softening and degradation in high temperature environment, which restricts the engineering application of FRP reinforcement technology in high temperature service scenarios such as bridges and tunnels, and new reinforcement adhesives with high temperature resistance and strong adhesion are urgently needed to be developed.

[0003] As a potential inorganic adhesive, alkali-activated materials have low carbon and environmental advantages compared with traditional cement-based materials, and can obtain bonding properties through a dissolution-repolymerization process and exhibit high heat resistance and chemical resistance. Using (aluminum-) siliceous materials as precursors can also promote the recycling of industrial by-products and help achieve sustainable development goals. However, the engineering performance of alkali-activated inorganic adhesives is very relevant to the precursors used. Differences in composition and structure of the precursors lead to different reaction products and microstructures, which in turn affect the working performance, mechanical properties and durability of the inorganic adhesives. Metakaolin (MK) and blast furnace slag (BFS) are two commonly used precursors. Previous studies have found that alkali-activated MK inorganic adhesives have advantages such as high temperature resistance, corrosion resistance, volume stability, and controllable performance of reaction products, but also have disadvantages such as slow hydration speed, long setting time, and low early strength. Alkali-activated BFS inorganic adhesives also have many advantages such as high early strength, low hydration heat, and excellent durability, but their volume shrinkage, fast setting and hardening speed, and easy cracking restrict their engineering application. Obviously, alkali-activated inorganic adhesives prepared from the above two single materials are not very ideal, but it is not difficult to find that there is a complementary possibility in performance between the two precursors. Alkali-activated MK-BFS inorganic adhesives are a new type of inorganic adhesives prepared by using suitable alkali activation technology based on the potential complementarity of the above two precursors in performance. The setting time is greatly shortened, the internal microstructure is reasonably optimized, and the overall performance is effectively improved, which has good engineering application prospects.

[0004] However, due to the complexity of the reaction process, multiple components of the system and the difference in the activity of the precursor, the alkali-activated MK-BFS inorganic glue faces many challenges in practical application, especially in the interface bonding performance, which is still insufficient, often showing low bonding strength with concrete base material, weak interface transition zone, unstable performance and other problems, which restricts its practical engineering application and promotion. Therefore, exploring the efficient bonding modification technology and optimization strategy of alkali-activated MK-BFS inorganic glue, analyzing its interface bonding behavior and failure characteristics, improving the interface bonding performance and expanding its engineering application have become the problems to be solved at present. SUMMARY

[0005] The technical problem to be solved by the present application is to provide an alkali-activated MK-BFS inorganic glue and its preparation method and application to solve the problems mentioned in the background art or achieve better technical effects.

[0006] In order to solve the above technical problems, the inventors have summarized and obtained the technical scheme of the present application through practice. The present application discloses an alkali-activated MK-BFS inorganic glue, which comprises a solid component and a liquid component. The solid component comprises 18.6-20 parts of MK, 74.4-80 parts of BFS and 0.3-7 parts of modified material. The liquid component comprises 41.82-62.74 parts of alkali activator and 9.68-13.68 parts of water. The use ratio of the solid component to the liquid component is 1.42-1.62:1.

[0007] The alkali activator is a compounded solution obtained by mixing NaOH and water glass solution. The mass ratio of NaOH to water glass solution is 0.16-0.25:1.

[0008] The modified material is selected from one or more of nano-SiO2, nano-Al2O3, wollastonite whisker and PVA fiber.

[0009] Further, the liquid component comprises 52.28 parts of alkali activator and 13.68 parts of water. In the alkali activator, the mass ratio of NaOH to water glass solution is 8.43:43.85.

[0010] Further, the particle size range of MK is 0.36-66.9 μm, and the specific surface area is 188.4-220.6 m 2 / kg. The particle size range of BFS is 0.31-76.0 μm, and the specific surface area is 208.5-235.9 m 2 / kg.

[0011] Further, in the alkali activator, the modulus of water glass is 1.0-1.4, and the Na2O content is 8.0-12.0%.

[0012] Further, the nano-SiO2 has a particle size of 15-30 nm and a specific surface area of 200-300 m 2 / g.

[0013] Further, the nano-Al2O3 has a particle size of 20-30 nm and a specific surface area of 150-200 m 2 / g.

[0014] Further, the wollastonite whisker has a density of 2.82-3.21 g / cm 3 , a particle size range of 0.36-35.3 μm.

[0015] Further, the PVA fiber has a length of 2-4 mm, a diameter of 12-16 μm and a density of 1.1-1.3 g / cm 3 .

[0016] Further, the nano-SiO2 has a mass ratio of 0.5-1.5% in the solid component.

[0017] Further, the nano-Al2O3 has a mass ratio of 3.0-7.0% in the solid component.

[0018] Further, the wollastonite whisker has a mass ratio of 3.0-7.0% in the solid component.

[0019] Further, the PVA fiber has a mass ratio of 0.3-0.7% in the solid component.

[0020] Further, the preparation method of the alkali-activated MK-BFS inorganic glue according to any one of the above has the following steps:

[0021] S1: inject NaOH into the water glass solution, and obtain a compound solution with a water glass modulus of 1.0-1.4 and a Na2O content of 8.0-12.0% by stirring, and obtain an alkaline activator after standing for 24 h;

[0022] S2: add 18.6-20 parts of MK and 74.4-80 parts of BFS into a cement paste stirring pot, dry mix for 3 min, and obtain a mixed powder;

[0023] S3: add the modified material to the mixed powder obtained in S2 according to the proportion, and obtain a mixture after stirring;

[0024] S4: inject 41.82-62.74 parts of the alkaline activator prepared in S1 and 9.68-13.68 parts of water into 100 parts of the mixture obtained in S3, and obtain the alkali-activated MK-BFS inorganic glue after slow stirring and fast stirring.

[0025] Further, the application of the alkali-activated MK-BFS inorganic glue in reinforcing concrete.

[0026] Compared with the prior art, the application has the following advantages:

[0027] (1) The application utilizes nano-SiO2 (NS), nano-Al2O3 (NA), wollastonite whisker (WS) and PVA fiber (PF) interface modification materials to modify the interface bonding of the alkali-activated MK-BFS inorganic glue from the micro-aggregate effect, surface effect and multi-scale interface improvement effect of the nano-materials with ultra-fine particle size and the crack bridging characteristics of the organic or inorganic fibers (whiskers), so as to improve the interface bonding performance of FRP-concrete.

[0028] (2) The application can improve the interface bonding strength of the sample by adding NS, and the interface bonding strength of the sample of different ages increases first and then decreases with the increase of the adding amount, the interface bonding strength of the sample with the adding amount of 1.0% at 7d is increased by 15.7%, 11.6% and 17.9% respectively compared with the blank sample, the sample with the adding amount of 0.5% and the sample with the adding amount of 1.5% at the same age; NS can improve the interface bonding performance through multiple ways such as physical filling, nucleation site and surface characteristics.

[0029] (3) The application can improve the interface bonding strength of the sample by adding NA, and the interface bonding strength of the sample at 7d and 28d increases first and then decreases with the increase of the adding amount of NA, the interface bonding strength of the sample with the adding amount of 5.0% at 28d is increased by 29.5%, 16.4% and 28.7% respectively compared with the blank sample, the sample with the adding amount of 3.0% and the sample with the adding amount of 7.0%; however, the interface bonding strength of the sample at 3d increases with the increase of the adding amount of NA; NA can improve the interface bonding from multiple aspects such as amorphous region control and interface densification, surface effect and chemical bonding, crack resistance and ion migration and reaction promotion.

[0030] (4) The application can improve the interface bonding strength of the sample by adding the fibrous WS with high aspect ratio, and the interface bonding strength of the sample of different ages increases first and then decreases with the increase of the adding amount of WS; the interface bonding strength of the sample with the adding amount of 5.0% at 7d is increased by 27.1% compared with the blank sample at the same age, and is increased by 8.7% and 6.0% respectively compared with the sample with the adding amount of 3.0% and the sample with the adding amount of 7.0%; WS can improve the interface bonding performance through multiple ways such as mechanical interlocking effect, induced adsorption nucleation, gel formation promotion and crack bridging.

[0031] (5) The application improves the interface bonding strength of the sample by incorporating the appropriate amount of PF, and the interface bonding strength of the sample with 0.5% PF is improved by 34.0% compared with the blank sample after 3d. With the increase of the PF content, the interface bonding strength increases first and then decreases, and the interface bonding strength of the sample with 0.5% PF is improved by 6.0%, 5.2% and 18.4% respectively compared with the blank sample, the sample with 0.3% PF and the sample with 0.7% PF after 28d. PF realizes the interface bonding enhancement in multiple ways such as physical combination and mechanical anchoring, chemical bonding, interface transition zone optimization, stress transfer and bridging effect.

[0032] (6) The application improves the interface bonding strength of the sample by mixing the above one or more modified materials, fully utilizes the synergistic effect of different modified materials, improves the interface compatibility, forms a more complex interface transition layer, increases the number of mechanical occlusion points and chemical bonds, and promotes the physical entanglement and chemical crosslinking to jointly enhance the interface bonding strength. At the same time, the mixed modified materials can also make good use of the modulus difference of the materials, effectively disperse the interface stress concentration and reduce the risk of matrix cracking. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Fig. 7 is a damage characteristic diagram of the sample with different NS contents according to the application after 7d; wherein, (a) is a blank sample; (b) is a sample with 0.5% NS; (c) is a sample with 1.0% NS; (d) is a sample with 1.5% NS;

[0034] Figure 2 Fig. 8 is a damage characteristic diagram of the sample with 1.0% NS content and different curing ages according to the application; wherein, (a) is cured for 3d; (b) is cured for 7d; (c) is cured for 28d;

[0035] Figure 3 Fig. 9 is an influence diagram of the NS content and the curing age on the average interface bonding strength and the compressive strength of the sample according to the application;

[0036] Figure 4 Fig. 10 is a damage characteristic diagram of the sample with different NA contents according to the application after 7d; wherein, (a) is a blank sample; (b) is a sample with 3.0% NA; (c) is a sample with 5.0% NA; (d) is a sample with 7.0% NA;

[0037] Figure 5 Fig. 11 is a damage characteristic diagram of the sample with 5.0% NA content and different curing ages according to the application; wherein, (a) is cured for 3d; (b) is cured for 7d; (c) is cured for 28d;

[0038] Figure 6 Fig. 12 is an influence diagram of the NA content and the curing age on the average interface bonding strength and the compressive strength of the sample according to the application;

[0039] Figure 7The 7d failure characteristic map of the sample with different WS contents of the application; wherein, (a) is a blank sample; (b) is a sample with a content of 3.0%; (c) is a sample with a content of 5.0%; (d) is a sample with a content of 7.0%;

[0040] Figure 8 The 7d failure characteristic map of the sample with different curing ages and a content of 5.0% WS of the application; wherein, (a) is cured for 3d; (b) is cured for 7d; (c) is cured for 28d;

[0041] Figure 9 The influence diagram of the WS content and the curing age on the average interfacial bonding strength and the compressive strength of the sample of the application;

[0042] Figure 10 The 7d failure characteristic map of the sample with different PF contents of the application; wherein, (a) is a blank sample; (b) is a sample with a content of 0.3%; (c) is a sample with a content of 0.5%; (d) is a sample with a content of 0.7%;

[0043] Figure 11 The 7d failure characteristic map of the sample with different curing ages and a content of 0.5% PF of the application; wherein, (a) is cured for 3d; (b) is cured for 7d; (c) is cured for 28d;

[0044] Figure 12 The influence diagram of the PF content and the curing age on the average interfacial bonding strength and the compressive strength of the sample of the application;

[0045] Figure 13 The physical map of the two kinds of nanomaterials NS and NA of the application; wherein, (a) is the physical map of NS; (b) is the physical map of NA;

[0046] Figure 14 The SEM map of the two kinds of nanomaterials NS and NA of the application; wherein, (a) is the SEM map of NS; (b) is the SEM map of NA;

[0047] Figure 15 The physical map of WS of the application;

[0048] Figure 16 The particle size distribution map of WS of the application;

[0049] Figure 17 The XRD map of WS of the application;

[0050] Figure 18 The SEM map of WS of the application;

[0051] Figure 19 The physical map of PF used in the application;

[0052] Figure 20It is an interface bonding test loading device of the application; wherein, (a) is a detachable steel test model; (b) is an interface bonding test diagram. DETAILED DESCRIPTION

[0053] In order to make the above objectives, characteristics and advantages of the application more obvious and easy to understand, the specific embodiments of the application will be described in detail below.

[0054] The raw materials or reagents used in the following examples and comparative examples are commercially available products or products prepared by conventional technical means unless otherwise specified.

[0055] Among them, the metakaolin (MK) used in the application is from Inner Mongolia Chaopai New Material Co., Ltd.; the density, activity index and specific surface area of the material are 2.626 g / cm 3 , 130%, 188.4~220.6 m 2 / kg, respectively. MK is mainly amorphous phase, containing a small amount of crystal phase such as mullite, wollastonite and quartz. SEM observation of the microstructure of MK shows that MK is flaky, with a size of about 0.36-66.9 μm, and there is agglomeration between particles. The main physical properties of MK are shown in Table 1, and the composition is shown in Table 2.

[0056] Table 1 Main physical properties of MK

[0057]

[0058] Table 2 Composition of MK

[0059]

[0060] Blast furnace slag: The blast furnace slag (BFS) used in the application is from Anhui Magang Jiahua New Building Material Co., Ltd., with a density, activity index and specific surface area of 2.892 g / cm 3 , 72.6%, 208.5~235.9 m 2 / kg, respectively. The main physical properties of BFS are shown in Table 3, and the main components of BFS are measured by XRF and shown in Table 4; the phase composition of BFS is analyzed by XRD, and it is found that BFS is irregular angular particles with a size of 0.31~76.0 μm.

[0061] Table 3 Main physical properties of BFS

[0062]

[0063] Table 4 Composition of BFS

[0064]

[0065] Alkaline activator raw material (water glass solution): commercially available industrial grade high-purity water glass solution with a modulus of 3.22, a Baume degree of 16.5, and a density of 1.38 g / cm 3 The weight ratio of the components is: Na2O is 8.50%, SiO2 is 26.80%, water insoluble matter is 0.36%, and water is 64.34%. Commercially available NaOH (density 2.13g / cm 3 ) Adjust the water glass modulus (SiO2 / Na2O) and Na2O content, and age it for 24 hours before use.

[0066] Among them, the manufacturers and physical parameters of nano-SiO2 (NS) and nano-Al2O3 (NA) are shown in Table 5 below. The actual photos of the two nanomaterials are shown in Figure 13 Its microscopic morphology is shown in Figure 14 shown.

[0067] Table 5 Manufacturer information and physical properties of NS and NA

[0068]

[0069] Wollastonite whiskers (WS) are from Lingshou County Dexu Mineral Products Processing Plant. Figure 15 As shown, the density, thermal expansion coefficient and whiteness of the material are 2.82~3.21g / cm 3 , 3.0 and 98%, its main physical properties are shown in Table 6, and its main components measured by XRF are shown in Table 7. Its particle size distribution measured by laser particle size analyzer is shown in Table 7. Figure 16 The XRD analysis of its phase composition is shown in Figure 17 Its microscopic morphology is shown in Figure 18 As shown, the shapes are needle-like or fibrous, and the aggregates are mostly radial.

[0070] Table 6 Main physical properties of WS

[0071]

[0072] Table 7 Composition of WS

[0073]

[0074] The PVA fiber (PF) used in this invention comes from Shandong Tonghui New Materials Co., Ltd. Figure 19 Its main physical properties are shown in Table 8 below.

[0075] Table 8 Main physical properties of PF

[0076]

[0077] The alkali-activated MK-BFS inorganic adhesive in each embodiment of the present application is cured by a standard curing method, and the curing age is 3d, 7d or 28d.

[0078] The performance test method of the modified alkali-activated MK-BFS inorganic adhesive is as follows:

[0079] Interface bonding strength: a detachable steel test mold as shown in Figure 20 (a) is designed, and the interface bonding test is performed on an MTS electro-hydraulic servo universal testing machine as shown in Figure 20 (b), the test adopts displacement control, and the loading speed is 1 mm / min.

[0080] Compressive strength: the flexural and compressive strengths of the MK-BFS inorganic adhesive are determined according to the recommended method of “Cement mortar strength test method (ISO method)” (GB / T 17671-2021). The sample size is 40mm x 40mm x 160mm, the sample is cured to the designed age, and then the flexural strength test is performed first, an electric flexural testing machine (model: DKZ-6000) is used for the test, the loading speed is 50N / s±10N / s, and then the compressive strength test is performed, a cement pressure testing machine (model: TYE-2000) is used, and the loading speed is 0.5-1.0MPa / s.

[0081] Example 1

[0082] An alkali-activated MK-BFS inorganic adhesive, the amount of each component is as follows in parts by weight: 19.9 parts of MK, 79.6 parts of BFS, 43.85 parts of water glass, 8.43 parts of NaOH, 13.68 parts of water, and 0.5 parts of NS.

[0083] The preparation method of the above-mentioned alkali-activated MK-BFS inorganic adhesive is as follows:

[0084] (1) Preparation of alkali activator: slowly inject NaOH with a density of 2.13g / cm 3 into the water glass solution, continuously stir with a glass rod to obtain a compound solution with a water glass modulus (SiO2 / Na2O) of 1.2 and a Na2O content of 10%, place the prepared compound solution in a beaker, cool it to room temperature and stand for 24h, and then obtain the alkali activator.

[0085] (2) Add 19.9 parts of MK and 79.6 parts of BFS into a cement paste stirring pot, raise it to a fixed position, and use a cement paste stirring machine with a model of NJ-160B to stir at a speed of 140r / min for 3min to make the MK and BFS fully mixed. Low-speed stirring can avoid material splashing, and also can better ensure the uniform mixing of the two materials.

[0086] (3) 0.5 parts of NS was added to 13.68 parts of water in a beaker, and ultrasonic dispersion was performed for 20 min using an ultrasonic disperser of model KH2200B to obtain a uniform NS suspension. Ultrasonic treatment can quickly and uniformly disperse nanoparticles, effectively avoid particle agglomeration, and improve the dispersibility and stability of NS; if the ultrasonic treatment time is too short, the dispersion is insufficient, and if the time is too long, secondary agglomeration is easily induced. The addition of an appropriate amount of water is conducive to the uniform dispersion of powdered NS, and can also reasonably adjust the fluidity of the inorganic glue to ensure its bonding effect.

[0087] (4) The NS suspension was added to the mixed powder obtained in step (2), and stirring was performed at a speed of 140 r / min for 3 min using a cement paste mixer of model NJ-160B, and after the materials were uniformly mixed, a mixture was obtained. During the preparation of the NS suspension, physical filling occurs during the contact with the mixture, and based on the micro-size effect, the NS is well filled and embedded in the micro-pores.

[0088] (5) 52.28 parts of the alkaline activator prepared in step (1) was injected into 113.68 parts of the mixture obtained in step (4), and stirring was performed at a speed of 140 r / min for 1 min using a cement paste mixer of model NJ-160B to ensure the preliminary wetting and dispersion of MK and BFS particles, and to ensure sufficient contact between the mixed solution and the particles. Low-speed stirring in the early stage can prevent the splashing of the activator and water, and can also reduce internal bubbles and avoid local clumping; then, the cement paste mixer was started at a speed of 285 r / min for fast stirring for 2 min to completely disperse the particles, further mix the materials uniformly, improve the reaction efficiency and improve the fluidity, and at the same time, shorten the total stirring time, and thus the NS-modified alkaline MK-BFS inorganic glue was obtained; during this process, “dissolution-polymerization” and geopolymerization reactions occur simultaneously to generate N-A-S-H and C-(A)-S-H gels, and NS acts as an efficient nucleation site to promote the enrichment and reaction of Ca 2⁺ on its surface, accelerate the nucleation of early C-(A)-S-H and N-A-S-H gels, and form a complex and stable three-dimensional network structure. At the same time, the NS with high pozzolanic activity can adsorb and enrich water molecules in the system due to its hydrophilicity and high specific surface area, and can promote the system to form a flocculation-like microstructure, thereby effectively enhancing the interfacial bonding strength of the inorganic glue. In addition, the -OH on the surface of NS can chemically bond with the silicate network in the alkaline activation system, further enhancing the interfacial bonding strength and reducing the risk of interfacial debonding.

[0089] Example 2

[0090] An alkali-activated MK-BFS inorganic glue comprises the following components in parts by weight: 19.8 parts of MK, 79.2 parts of BFS, 43.85 parts of water glass, 8.43 parts of NaOH, 13.68 parts of water, and 1.0 part of NS.

[0091] The preparation method of the above-mentioned alkali-activated MK-BFS inorganic glue is the same as that in Example 1.

[0092] Example 3

[0093] An alkali-activated MK-BFS inorganic glue comprises the following components in parts by weight: 19.7 parts of MK, 78.8 parts of BFS, 43.85 parts of water glass, 8.43 parts of NaOH, 13.68 parts of water, and 1.5 parts of NS.

[0094] The preparation method of the above-mentioned alkali-activated MK-BFS inorganic glue is the same as that in Example 1.

[0095] Depend on Figure 1 (a) It can be seen that the failure of the blank sample is mainly manifested as the end failure of the anchoring zone, which is mainly attributed to the insufficient bonding strength of the unmodified alkali-activated MK-BFS inorganic adhesive. With the addition of NS, the failure of the samples with 0.5% and 1.5% NS content (the percentage here refers to the proportion of NS as an added modified substance in the entire solid component, the same below) is mainly manifested as CFRP cloth delamination failure, such as Figure 1 (b) and Figure 1 As shown in (d), on the one hand, it may be because the addition of too low or too high NS has limited improvement on the interfacial bonding performance of the inorganic adhesive; on the other hand, it may be due to the unsatisfactory wetting effect of the CFRP cloth in the inorganic adhesive during sample preparation. In comparison, the sample with 1.0% NS content mainly experienced delamination of the CFRP cloth accompanied by partial peeling of the adhesive layer adjacent to the concrete (mixed failure), as shown in Figure 5. Figure 1 (c) This shows that the addition of 1.0% NS can effectively improve the interfacial bonding strength of the sample and enhance the effective bonding between the inorganic adhesive and concrete.

[0096] like Figure 2 As shown in (a), the interface bonding failure characteristics of the specimens vary with the increase of curing age. The specimens cured for 3 days mainly suffer from CFRP fabric delamination failure. Figure 2 As shown in (b-c), samples cured for 7 and 28 days primarily experienced delamination of the CFRP sheet, accompanied by partial peeling of the adhesive layer from the adjacent concrete (mixed failure). The reasons for these two distinct failure modes are similar to those analyzed above. In the early stages of curing, the inorganic adhesive's bond strength is limited, making delamination of the CFRP sheet more likely to occur when exposed to external forces. However, as curing age increases, the inorganic adhesive's reaction becomes more complete, and the bond strength gradually increases, leading to the mixed failure mode described above.

[0097] Depend onFigure 3 It can be seen that the incorporation of NS can improve the interfacial bond strength and compressive strength of the sample well. Compared with the blank sample, the interfacial bond strength and compressive strength of the 1.0% NS sample at 7d are increased by 15.7% and 39.8% respectively. This is mainly due to the characteristics of NS, such as small particle size, large specific surface area and high activity. Without the incorporation of NS, the “dissolution-polycondensation” and geopolymerization reactions of the system are relatively slow, the number of generated gels is small, and the microstructure of the material has more pores and poor compactness. The incorporation of NS not only increases the active sites of the system, but also plays a filling and nucleation role, promoting the generation of gels and the densification of the microstructure. Similar studies have also confirmed that the incorporation of NS promotes the reaction of alkali-activated systems. However, with the increase of NS content, the interfacial bond strength and compressive strength of different age samples all show a trend of first increasing and then decreasing. The interfacial bond strength and compressive strength of the 1.0% NS sample at 28d are increased by 4.1%, 4.3%, 19.0% and 8.1% compared with the 0.5% and 1.5% NS samples at the same age. This is mainly because when the NS content is too low, NS can only provide limited active sites and filling effect, and the improvement of the microstructure and the increase of the strength are not obvious. With the further increase of the content, the appropriate amount of NS can fully play its physical filling and crystallization nucleation effect, and effectively promote the generation of reaction products, optimize the internal pore structure, and improve the interfacial bond strength and compressive strength. When the NS content is too high, the NS particles aggregate to form large-size agglomerates, which not only reduces the pore filling efficiency, but also inhibits the generation and diffusion of reaction products, which is not conducive to the improvement of the bond strength and compressive strength.

[0098] By Figure 3 It can also be found that with the extension of curing age, the interfacial bond strength and compressive strength of all samples show a growth trend. Compared with the 3d sample, the interfacial bond strength and compressive strength of the 1.0% NS sample at 28d are increased by 70.8% and 53.1% respectively. With the extension of curing age, the system tends to be complete, and the generation speed of gel products slows down, resulting in that the strength growth is not as obvious as the early stage. It is worth noting that the incorporation of NS can promote the rapid development of the interfacial bond strength and compressive strength of the sample. The interfacial bond strength and compressive strength of the blank sample at 7d are 87.0% and 72.8% of the interfacial bond strength and compressive strength at 28d respectively, while the interfacial bond strength and compressive strength of the 0.5%, 1.0% and 1.5% NS samples at 7d are 89.7% and 91.5%, 96.1% and 97.5%, 97.0% and 96.9% of the interfacial bond strength and compressive strength at 28d respectively.

[0099] The NS in Examples 1-3 effectively improves the interfacial bonding performance and mechanical properties of the sample through the synergistic effect of multiple pathways such as physical filling, nucleation site, surface properties, etc. First, based on the micro-size effect, the NS fills and embeds the micro-pores well, effectively reduces the interfacial porosity, enhances the mechanical interlocking effect between the inorganic glue and the adherend, and significantly improves the interfacial bonding strength of the sample; second, as an efficient nucleation site, the NS promotes the nucleation of Ca 2+ on its surface and reacts to accelerate the nucleation of early C-(A)-S-H, N-A-S-H gel, forming a complex and stable three-dimensional network structure; finally, the NS with high pozzolanic activity absorbs and enriches water molecules in the system due to its hydrophilicity and high specific surface area, which promotes the formation of a flocculent-like microstructure in the system, effectively enhancing the interfacial bonding strength of the inorganic glue; in addition, the -OH on the surface of the NS chemically bonds with the silicate network in the alkali-activated system, further enhancing the interfacial bonding strength and reducing the risk of interfacial debonding.

[0100] Example 4

[0101] An alkali-activated MK-BFS inorganic glue, the amount of each component is as follows: 19.4 parts of MK, 77.6 parts of BFS, 43.85 parts of water glass, 8.43 parts of NaOH, 13.68 parts of water, and 3 parts of NA.

[0102] The preparation method of the above-mentioned alkali-activated MK-BFS inorganic glue, the steps are as follows:

[0103] (1) Preparation of alkaline activator: slowly inject NaOH with a density of 2.13 g / cm 3 into the water glass solution, continuously stir with a glass rod to obtain a compound solution with a water glass modulus (SiO2 / Na2O) of 1.2 and a Na2O content of 10%, cool the prepared compound solution to room temperature and stand for 24 h, then obtain the alkaline activator.

[0104] (2) Add 19.4 parts of MK and 77.6 parts of BFS to a cement paste stirring pot, raise to a fixed position, and use a cement paste stirring machine with a model of NJ-160B to stir at a speed of 140 r / min for 3 min to make the MK and BFS mix well. Low-speed stirring can avoid material splashing, and also can better ensure the uniform mixing of the two materials.

[0105] (3) 3 parts of NA and 13.68 parts of water were added into a beaker, and an ultrasonic disperser with model number KH2200B was used for ultrasonic dispersion for 20 min to obtain a uniform NA suspension. Ultrasonic treatment can quickly and uniformly disperse nanoparticles, effectively avoid particle agglomeration, and improve the dispersity and stability of NA; if the time is too short, the dispersion is insufficient, and if the time is too long, secondary agglomeration is easily induced. The addition of an appropriate amount of water is conducive to the uniform dispersion of powdered NA, and can also reasonably adjust the fluidity of the inorganic glue to ensure its bonding effect.

[0106] (4) The NA suspension prepared in step (3) was injected into the mixed powder obtained in step (2), and a cement paste stirrer with model number NJ-160B was used for stirring at a speed of 140 r / min for 3 min, and after the materials were uniformly mixed, a mixture was obtained. During the preparation of the NA suspension and the contact process with the mixed material, physical filling occurs, and based on the micro-size effect, the NA is well filled and embedded in the micro-pores.

[0107] (5) 52.28 parts of the alkaline activator prepared in step (1) was injected into 113.68 parts of the mixture obtained in step (4), and a cement paste stirrer with model number NJ-160B was used for stirring at a speed of 140 r / min for 1 min to preliminarily wet and disperse the MK and BFS particles, so as to ensure sufficient contact between the mixed solution and the particles, and low-speed stirring in the early stage can prevent the splashing of the activator and water, and also can reduce internal bubbles and avoid local clumping; then, the cement paste stirrer was started at a speed of 285 r / min for fast stirring for 2 min to completely disperse the particles, further mix the materials uniformly, accelerate the system reaction and improve the fluidity, and at the same time, shorten the total stirring time, that is, to obtain the inorganic glue of the alkali-activated MK-BFS modified by the addition of NA; the addition of NA can well inhibit the crystallization process of the system, increase the proportion of amorphous regions, and the increase of amorphous structure helps to reduce the micro defects at the interface and improve the interface bonding density; at the same time, the NA particles are dispersed in the interface region, fill the micro-pores, and form a uniform transition layer to effectively reduce stress concentration; in addition, the NA has a high specific surface area and surface active sites, and chemical bonding (such as Si-O-Al or Al-O-Al bonds) occurs between the surface -OH and the silicate network in the alkali-activated system; the alkaline environment can promote the partial dissolution of the surface of the NA, release Al 3+ , participate in the generation of the cementitious product, and promote the crosslinking of the silicate network; in addition, the NA adjusts the ion migration (such as Na + , OH - ) near the interface through the surface charge effect, promotes the polymerization reaction and "dissolution-polymerization" reaction of the system, and accelerates the generation of the cementitious product.

[0108] Example 5

[0109] A kind of alkali-activated MK-BFS inorganic glue, by weight parts, the dosage of each component is as follows:19.0 parts MK, 76.0 parts BFS, 43.85 parts water glass, 8.43 parts NaOH, 13.68 parts water, 5 parts NA.

[0110] The preparation method of the above-mentioned alkali-activated MK-BFS inorganic glue is the same as that of Example 4.

[0111] Example 6

[0112] A kind of alkali-activated MK-BFS inorganic glue, by weight parts, the dosage of each component is as follows:18.6 parts MK, 74.4 parts BFS, 43.85 parts water glass, 8.43 parts NaOH, 13.68 parts water, 7 parts NA.

[0113] The preparation method of the above-mentioned alkali-activated MK-BFS inorganic glue is the same as that of Example 4.

[0114] As Figure 4 (a)~4 (b) can be seen, the blank sample and the failure of 3.0% NA content sample is mainly manifested as the end of anchorage zone failure, which is due to the insufficient bonding strength of alkali-activated MK-BFS inorganic glue. The failure of 5.0% and 7.0% NA content samples is mainly manifested as CFRP cloth delamination, as shown in Figure 4 (c)~4 (d). This shows that the increase of NA content leads to the increase of the interfacial bonding strength of the sample and the anchorage force of the end of the sample, so the sample with high NA content does not occur the above-mentioned end of anchorage zone failure. The occurrence of CFRP cloth delamination in the sample may be due to the fact that the impregnation effect of CFRP cloth in the inorganic glue is not ideal, and on the other hand, it may be because the load applied during the interfacial bonding test is eccentric, resulting in the occurrence of interface failure and the offset delamination of CFRP cloth. It is worth noting that the interfacial bonding strength of 3.0% and 7.0% NA content samples is not much different, which shows that too high NA content affects the impregnation effect of CFRP cloth in the inorganic glue.

[0115] With the increase of curing age, the interfacial bonding failure characteristics of the sample are also different, as shown in Figure 5 (a). The 3d sample mainly occurs end of anchorage zone failure at the early stage of curing; with the increase of curing age to 7d and 28d, the sample mainly occurs CFRP cloth delamination, as shown in Figure 5(b)~5(c) shown. The reason for the two different failure modes is similar to the above analysis, the lower bonding strength of the inorganic glue at the initial curing stage leads to the insufficient anchorage force at the end of the sample, and with the extension of the curing age, the bonding strength of the inorganic glue increases, effectively avoiding the failure of the end of the anchorage zone of the sample. Further analysis of the failure characteristics of the 28d curing sample shows that there is also a certain cementation between the glue layer and the CFRP cloth, which shows that prolonging the curing age of the sample not only changes the failure characteristics of the sample, but also helps to strengthen the bonding between the CFRP cloth and the inorganic glue.

[0116] As shown in Figure 6 The incorporation of NA can better improve the interfacial bonding strength and compressive strength of the sample. Compared with the blank sample, the interfacial bonding strength and compressive strength of the 5.0% sample at 28d are increased by 29.5% and 14.4% respectively. The interfacial bonding strength and compressive strength of the 7d and 28d samples increase first and then decrease with the increase of the NA content. Compared with the 3.0% and 7.0% samples, the interfacial bonding strength of the 5.0% sample at 28d is increased by 16.4% and 28.7% respectively, and the 28d compressive strength is increased by 11.8% and 27.3% respectively. This may be because the nano material itself has a unique micro-size effect, which can improve the uniformity of the microstructure and reduce stress concentration; at the same time, the incorporation of NA can increase the heat release during initial dissolution and accelerate the silicate reaction inside the system; in addition, the high specific surface area and surface energy characteristics of NA can act as a reaction nucleation and growth active center, playing a key role in the regulation of product phase structure and the improvement of material performance. However, due to the specific dissolution of NA in alkaline environment, its content has a significant impact on the particle size of the flocculation precipitation inside the system, so when the content reaches 7.0%, the agglomeration phenomenon of NA will occur, which will destroy the uniformity of the particle distribution inside the system and affect the mechanical properties of the sample. What is different is that for the 3d curing sample, the interfacial bonding strength and compressive strength increase with the increase of the NA content, and when the NA content is 7.0%, the interfacial bonding strength and compressive strength of the sample reach the maximum value, which is 0.788MPa and 50.0MPa respectively, because the reaction inside the system is relatively slow at the initial curing stage, and the influence of the agglomeration phenomenon on the overall performance of the sample is relatively small, and its role is within the controllable range.

[0117] Meanwhile, with the extension of curing age, the interfacial bond strength and compressive strength of the blank sample and the sample with different NA contents also increase. When the curing age increases from 3d to 28d, the interfacial bond strength and compressive strength of the blank sample increase by 112.6% and 132.6% respectively, and the interfacial bond strength and compressive strength of the sample with 5.0% NA content increase by 116.0% and 67.1% respectively, because the “dissolution-polycondensation” and polymerization reactions in the system gradually tend to be complete, the stable phases generated by the reactions continuously fill the voids and form a three-dimensional network structure, thereby reducing stress concentration and improving the strength of the sample. It is worth noting that when the age increases from 7d to 28d, the interfacial bond strength and compressive strength of the sample with 7.0% content only increase by 8.0% and 13.83% respectively, which further indicates that the agglomeration phenomenon caused by excessive NA content is not conducive to the development of the strength of the sample.

[0118] In Examples 4-6, the NA mainly regulates and realizes the interfacial bond enhancement from the aspects of interface densification, surface effect and chemical bonding, crack arrest, and ion migration and reaction promotion. First, the incorporation of NA can well inhibit the crystallization process of the system, increase the proportion of amorphous region, and the increase of amorphous structure helps to reduce the micro defects at the interface, improve the interface bonding density. At the same time, the NA particles are dispersed in the interface region, fill the micropores, and form a uniform transition layer, effectively reducing stress concentration; secondly, NA has high specific surface area and surface active sites, and through the chemical bonding (such as forming Si-O-Al or Al-O-Al bond) between surface-OH and silicate network in the alkali-activated system, the interfacial bond strength is enhanced, and the risk of interfacial debonding is reduced. At the same time, the alkaline environment can promote the partial dissolution of the surface of NA, release Al 3+ , participate in the generation of gel products, and promote the crosslinking of silicate network; thirdly, NA as a rigid particle, absorbs energy through “pinning effect”, effectively delays the propagation of microcracks; finally, NA adjusts the ion migration (such as Na + , OH - ) near the interface through surface charge effect, promotes the “dissolution-polycondensation” reaction of the system, and accelerates the generation of gel products at the interface. In addition, NA as an Al source supplement optimizes the Al / Si ratio of the reaction products and improves the chemical stability of the interface transition zone.

[0119] Example 7

[0120] An alkali-activated MK-BFS inorganic glue, the amount of each component is as follows in parts by weight: 19.4 parts of MK, 77.6 parts of BFS, 43.85 parts of water glass, 8.43 parts of NaOH, 13.68 parts of water, and 3 parts of WS.

[0121] The preparation method of the above-mentioned alkali-activated MK-BFS inorganic glue, the steps are as follows:

[0122] (1) Preparation of alkaline activator: slowly inject NaOH with a density of 2.13 g / cm 3 into the water glass solution, continuously stir with a glass rod to obtain a complex solution with a water glass modulus (SiO2 / Na2O) of 1.2 and a Na2O content of 10%, place the prepared complex solution in a beaker, cool to room temperature and stand for 24 h, then use as an alkaline activator;

[0123] (2) Add 19.4 parts of MK and 77.6 parts of BFS into a cement paste stirring pot, raise to a fixed position, and use a cement paste stirring machine with a model of NJ-160B to stir at a speed of 140 r / min for 3 min to make MK and BFS fully mixed. Low-speed stirring can avoid material splashing, and also can better ensure uniform mixing of the two materials.

[0124] (3) Add 3 parts of WS to the mixed powder obtained in step (2), and use a cement paste stirring machine with a model of NJ-160B to stir at a speed of 140 r / min for 3 min, and after the material is uniformly mixed, obtain a mixture; this process uses mechanical stirring to effectively realize the physical filling effect of WS, reduce porosity, and improve the density of the matrix.

[0125] (4) Inject 52.28 parts of the alkaline activator prepared in step (1) into 100 parts of the mixture obtained in step (3), and use a cement paste stirring machine with a model of NJ-160B to stir at a speed of 140 r / min for 1 min to make WS, MK and BFS particles preliminarily wet and dispersed, and ensure sufficient contact between the mixed liquid and the particles, and low-speed stirring in the early stage can prevent the splashing of the activator and water, and also can reduce internal bubbles and avoid local clumping; then, start the cement paste stirring machine to stir at a speed of 285 r / min for 2 min to realize rapid mixing through high-strength mechanical force, further make the materials uniformly mixed, improve the reaction efficiency, and shorten the total stirring time. In this process, "dissolution-polymerization" and polymerization reactions occur simultaneously, Ca 2+ and SiO3 2- dissociated from WS in the alkaline environment participate in the formation of C-(A)-S-H gel and the polycondensation reaction of oligomers, respectively, to form a network structure with higher polymerization degree; the active sites on the surface of WS (such as -OH, Ca 2+ , etc.) provide ideal adsorption positions for polymer molecular chains, reduce the energy required for crystallization nucleation, induce directional adsorption of polymer molecular chains, and promote the polymer to more easily nucleate on the surface of the whisker to form a dense interface transition zone.

[0126] (5) To the gel obtained in step (4), 13.68 parts of water was added, and after rapid stirring for 3 min, a WS-modified alkali-activated MK-BFS inorganic adhesive was obtained; the fluidity of the inorganic adhesive was adjusted by adding an appropriate amount of water to ensure its bonding effect. The high aspect ratio fibrous WS effectively embedded in the gel network to play a mechanical interlocking effect and promote gel penetration, realizing effective load transfer; in addition, the three-dimensional network structure formed by WS when filling the pores has a bridging stress effect, forming numerous tiny "bridges" in the material to connect and support adjacent gel particles, effectively transferring and dispersing shrinkage stress, and significantly inhibiting crack initiation and propagation behavior caused by shrinkage stress concentration.

[0127] Example 8

[0128] An alkali-activated MK-BFS inorganic adhesive, the amount of each component is as follows: 19.0 parts of MK, 76.0 parts of BFS, 43.85 parts of water glass, 8.43 parts of NaOH, 13.68 parts of water, and 5 parts of WS.

[0129] The preparation method of the above-mentioned alkali-activated MK-BFS inorganic adhesive is the same as that of Example 7.

[0130] Example 9

[0131] An alkali-activated MK-BFS inorganic adhesive, the amount of each component is as follows: 18.6 parts of MK, 74.4 parts of BFS, 43.85 parts of water glass, 8.43 parts of NaOH, 13.68 parts of water, and 7 parts of WS.

[0132] The preparation method of the above-mentioned alkali-activated MK-BFS inorganic adhesive is the same as that of Example 7.

[0133] As Figure 7 (a) shows, the damage of the blank sample is mainly manifested as the end damage of the anchorage zone, which is due to the insufficient bonding strength of the alkali-activated MK-BFS inorganic adhesive. With the incorporation of WS, the damage of the 3.0% and 7.0% WS content samples is mainly manifested as the delamination damage of the CFRP cloth, as shown in Figure 7 (b) and 7(d). This may be because the CFRP cloth has an unsatisfactory infiltration effect in the inorganic adhesive with too high or too low WS content, resulting in the offset delamination of the CFRP cloth when the interface damage of the sample occurs. In comparison, the 5.0% WS content sample has CFRP cloth delamination damage, accompanied by partial peeling damage of the adhesive layer adjacent to the concrete (mixed damage), as shown in Figure 7 (c). This shows that the incorporation of 5.0% WS can better improve the interfacial bonding performance of the inorganic adhesive and the concrete. At the same time, the interfacial bonding damage characteristics of the sample also differ with the extension of the curing age, as shown in Figure 8(a) and (b) show that the 3d specimens mainly occur anchorage zone end failure, the reasons for this failure form consistent with the above analysis, maintenance of 7d and 28d specimens mainly occur CFRP cloth delamination failure accompanied by partial peeling of the adhesive layer adjacent to the concrete (mixed failure), as shown in Figure 8 (b) and (c) shown. This is due to the inorganic glue reaction in the system tends to be complete, the adhesion of inorganic glue is enhanced, the interfacial bonding strength of the specimen increases, leading to the emergence of the above mixed failure mode.

[0134] As shown in Figure 9 , the incorporation of WS can better improve the interfacial bonding strength of different age specimens, with the increase of WS content, the interfacial bonding strength of different age specimens increases first and then decreases. The 7d interfacial bonding strength of WS content 5.0% specimen is 27.12% higher than that of the same age blank sample, and 8.66% and 6.01% higher than that of 3.0% and 7.0% content specimens respectively. This is mainly because WS releases Ca 2+ It can accelerate the "dissolution-polycondensation" of BFS and the polymerization reaction of MK, generate a large amount of C-(A)-S-H and N-A-S-H gel, leading to the increase of the contact area between the gel and the interface, thereby improving the interfacial bonding performance of the specimen. However, the incorporation of excessive WS will destroy the particle packing state in the system, affect the internal mechanical engagement, and lead to the decrease of the interfacial bonding performance. From Figure 9 It can be seen that the incorporation of WS is beneficial to improve the compressive strength of different age specimens, with the increase of WS content, the compressive strength of the specimen presents the similar change rule as the interfacial bonding strength, the 7d compressive strength of 5.0% WS content specimen is 37.1%, 16.5% and 19.7% higher than that of the same age blank sample, 3.0% and 7.0% WS content specimens respectively. This is mainly due to the needle-like or fibrous (aggregate is mainly radial) WS can better fill the micro-pores of the system, and the dense internal structure, while WS has pozzolanic activity, and appropriate incorporation can also participate in the system reaction to generate C-(A)-S-H gel, better adjust the microstructure of the product, and optimize the internal pore size distribution, thereby enhancing the compressive strength of the specimen. However, the incorporation of excessive WS will have adverse effects on the strength, on the one hand, excessive WS will inhibit the system reaction and reduce the generation of reaction products; on the other hand, it will destroy the originally reasonable particle packing state, leading to the increase of the void ratio between particles and the increase of the matrix pore, and the decrease of the strength.

[0135] As shown in Figure 9It is also found that the interfacial bond strength and compressive strength of all samples gradually increase with the extension of curing age. Compared with the 3d sample, the interfacial bond strength and compressive strength of the 5.0% WS dosage sample increase by 98.1% and 91.7% respectively at 28d. This is mainly because with the extension of curing age, the "dissolution-polycondensation" and geopolymerization reactions in the system are more and more sufficient, the reaction products C-(A)-S-H and N-A-S-H gel increase continuously, forming a stable three-dimensional network structure, and the interface transition zone gradually becomes uniform and dense, which significantly improves the compressive strength. The large amount of gel not only optimizes the internal pore structure, but also improves the gelation performance of the system, thereby increasing the interfacial bond strength. It is worth noting that the incorporation of WS can promote the rapid development of the compressive strength of the sample. The 7d compressive strength of the blank sample is 72.8% of its 28d compressive strength, while the 7d compressive strength of the WS dosage 3.0%, 5.0%, 7.0% sample reaches 91.3%, 80.5%, 93.0% of the corresponding 28d compressive strength. On the one hand, WS decomposes a large amount of Ca 2+ in the strong alkaline environment, promotes the simultaneous occurrence of "dissolution-polycondensation" and polymerization reactions, and the interaction of the generated gel improves the early strength; on the other hand, WS particles act as nucleation sites, providing more reaction sites and better optimizing the internal microstructure.

[0136] The WS in Examples 7-9 mainly optimizes the interfacial bond performance of the sample through mechanical interlocking effect, promotion of gel generation, induced adsorption nucleation, and crack bridging, etc. Its enhancement effect mainly reflects in the following aspects: first, the high aspect ratio fibrous WS embeds into the gel network by virtue of its surface micro-protrusion characteristics, plays a mechanical interlocking effect, promotes gel penetration, and realizes effective load transfer; second, the dissociated Ca 2+ and SiO3 2- in the alkaline environment participate in the formation of C-(A)-S-H gel and the polycondensation reaction of oligomers respectively, forming a network structure with higher polymerization degree; third, the active sites (such as -OH, Ca 2+ , etc.) on the surface of WS provide ideal adsorption sites for polymer molecular chains, reduce the energy required for crystalline nucleation, induce directional adsorption of polymer molecular chains, and promote the nucleation of polymers on the surface of whiskers, forming a dense interface transition zone; in addition, WS also realizes stress redistribution through crack bridging mechanism, effectively blocks the crack propagation path, and improves the toughness of the matrix.

[0137] Example 10

[0138] An alkali-activated MK-BFS inorganic glue, the amount of each component is as follows in parts by weight: 19.94 parts of MK, 79.76 parts of BFS, 43.85 parts of water glass, 8.43 parts of NaOH, 13.68 parts of water, and 0.3 parts of PF.

[0139] The preparation method of the alkali-activated MK-BFS inorganic glue comprises the following steps:

[0140] (1) Preparation of the alkali activator: slowly inject NaOH with a density of 2.13 g / cm 3 into the water glass solution, continuously stir with a glass rod to obtain a compound solution with a water glass modulus (SiO2 / Na2O) of 1.2 and a Na2O content of 10%, place the prepared compound solution in a beaker, cool to room temperature, and stand for 24 h to obtain the alkali activator.

[0141] (2) Add 19.94 parts of MK and 79.76 parts of BFS into a cement paste stirring pot, and raise to a fixed position, and then use a cement paste stirring machine with a model of NJ-160B to stir at a speed of 140 r / min for 3 min, so that the MK and BFS are fully mixed. Low-speed stirring can avoid material splashing, and can also better ensure uniform mixing of the two materials.

[0142] (3) Add 0.3 parts of PF to 52.28 parts of the alkali activator prepared in step (1), and add 13.68 parts of water in the beaker, and fully stir to obtain a mixed solution; this process occurs physical combination, and through mechanical stirring, the PF fully contacts with the alkali activator, the PF surface slightly swells in the alkaline environment, which increases the surface roughness of the PF, and is beneficial to the combination of the PF with the gel generated in the system to form a physical interlocking structure.

[0143] (4) Pour the mixed solution prepared in step (3) into the mixed powder in step (2), and use a cement paste stirring machine with a model of NJ-160B to stir at a speed of 140 r / min for 1 min, so that the MK and BFS particles are wetted and dispersed, and the mixed solution and the particles are fully contacted; the low-speed stirring in the early stage can prevent the splashing of the activator and water, and can also reduce internal bubbles and avoid local clumping; then, start the cement paste stirring machine at a speed of 285 r / min for 2 min, so that the collision and crosslinking of the gel particles are accelerated, the material is further mixed uniformly, the preliminary formation of the three-dimensional network structure is promoted, the fluidity is improved, and the total stirring time is shortened, that is, the alkali-activated MK-BFS inorganic glue doped with PF modification is obtained; due to the addition of PF, this process can effectively inhibit the expansion of microcracks and form a uniform interface structure; at the same time, the surface -OH of the PF is negatively charged, and can attract Ca 2+The "ion adsorption layer" is generated, which promotes the heterogeneous nucleation of C-(A)-S-H gel on its surface to form a transition zone with low porosity; in addition, part of -OH also reacts with Si-OH or Al-OH in the gel to form Si-O-C bonds, and the chemical bonding effect is enhanced; furthermore, the flexible PF ensures the effective transmission and release of tensile stress through good "bridging" effect, delays the initiation and expansion of matrix microcracks, thereby improving the toughness and interfacial bonding performance of the material.

[0144] Example 11

[0145] An alkali-activated MK-BFS inorganic glue, the amount of each component is as follows: 19.9 parts of MK, 79.6 parts of BFS, 43.85 parts of water glass, 8.43 parts of NaOH, 13.68 parts of water, 0.5 parts of PF.

[0146] The preparation method of the above-mentioned alkali-activated MK-BFS inorganic glue is the same as that of Example 10.

[0147] Example 12

[0148] An alkali-activated MK-BFS inorganic glue, the amount of each component is as follows: 19.86 parts of MK, 79.44 parts of BFS, 43.85 parts of water glass, 8.43 parts of NaOH, 13.68 parts of water, 0.7 parts of PF.

[0149] The preparation method of the above-mentioned alkali-activated MK-BFS inorganic glue is the same as that of Example 10.

[0150] As Figure 10 As shown in (a), the bonding strength of the alkali-activated MK-BFS inorganic glue is insufficient, and the failure of the blank sample mainly occurs at the end of the anchorage zone. With the addition of PF, the failure of the sample shows CFRP cloth delamination, as shown in (b-d). Figure 10 As shown in (a), the bonding strength of the alkali-activated MK-BFS inorganic glue is insufficient, and the failure of the blank sample mainly occurs at the end of the anchorage zone. With the addition of PF, the failure of the sample shows CFRP cloth delamination, as shown in (b-d). Figure 11 As shown in (a), the bonding strength of the alkali-activated MK-BFS inorganic glue is insufficient, and the failure of the blank sample mainly occurs at the end of the anchorage zone. With the addition of PF, the failure of the sample shows CFRP cloth delamination, as shown in (b-d). Figure 11 As shown in (a), the bonding strength of the alkali-activated MK-BFS inorganic glue is insufficient, and the failure of the blank sample mainly occurs at the end of the anchorage zone. With the addition of PF, the failure of the sample shows CFRP cloth delamination, as shown in (b-d).

[0151] As shown in (a), the bonding strength of the alkali-activated MK-BFS inorganic glue is insufficient, and the failure of the blank sample mainly occurs at the end of the anchorage zone. With the addition of PF, the failure of the sample shows CFRP cloth delamination, as shown in (b-d). Figure 12As shown in the figure, the incorporation of an appropriate amount of PF significantly improves the interfacial bond strength of the specimens. Compared with the blank, the 3-day interfacial bond strength of the specimen with a 0.5% PF content increased by 34.0%. With increasing PF content, the interfacial bond strength of the specimens first increases and then decreases. The 28-day interfacial bond strength of the specimen with a 0.5% PF content increases by 5.19% and 18.37%, respectively, compared with the specimens with 0.3% and 0.7% PF content at the same age. This is because when the PF content is low, the fibers cannot form a complete three-dimensional reinforcement network, making it difficult to effectively bridge microcracks, resulting in a negligible improvement in interfacial bonding. The incorporation of an appropriate amount of PF can promote slight hydrolysis of the fiber surface in an alkaline environment, generating more polar groups (such as -OH), strengthening interfacial chemical bonding, and thus improving interfacial bond strength. However, excessive PF incorporation can adversely affect the interfacial bonding properties of the specimens, even resulting in lower interfacial bond strength than that of the blank. This is mainly due to the adsorption of water film or air on the fiber surface, which increases the thickness of its interface transition zone and degenerates the bonding form from "chemical bonding" to weak physical adsorption. The fibers are easily slipped and pulled out, resulting in a decrease in its interface bonding strength. With the increase of PF content, the compressive strength of the sample also shows a similar change pattern. The 7-day compressive strength of the sample with 0.5% PF content is 4.6% and 5.9% higher than that of the samples with 0.3% and 0.7% PF content, respectively. This shows that the addition of an appropriate amount of PF can reduce microcracks within the matrix through physical crack prevention and bridging effects, especially shrinkage cracks in the interface transition zone, improve the matrix density, and thus improve its compressive strength.

[0152] At the same time, with the increase of curing age, the interfacial bonding strength and compressive strength of samples with different PF content increased. The interfacial bonding strength and compressive strength of the sample with 0.5% PF content at 28 days increased by 112.8% and 80.3% respectively compared with the sample with 3 days. This may be because in an alkaline environment, the -OH on the PF molecular chain reacts with some metal ions in the system (such as Al 3+ 、Si 4+ ) undergoes a polycondensation reaction to form covalent bonds, strengthening the bond between PF and the matrix and improving the interfacial bonding strength and compressive strength of the specimens. Notably, compared to the 7-day specimen, the 28-day interfacial bonding strength and compressive strength of the 0.7% PF-doped specimen increased by only 9.0% and 9.5%, respectively. This further demonstrates that excessive PF addition can lead to internal microcracks, hindering strength development.

[0153] The PF in Examples 10-12 synergistically enhances interfacial bonding performance through multiple pathways, including physical bonding and mechanical anchoring, chemical bonding, optimization of the interface transition zone, stress transfer, and bridging effects. First, the PF surface swells slightly in an alkaline environment, resulting in increased surface roughness, which combines with the generated gel to form a physical interlocking structure. Simultaneously, during stirring, the PF forms curved or hooked ends, further enhancing its mechanical anchoring effect. Second, some -OH groups in the PF are deprotonated to form -O -Ca 2+ or Al 3+ reacts to form Ca / Al-O structure, and part of -OH also reacts with Si-OH or Al-OH in the gel to form hydrogen bond, resulting in the formation of Si-O-C bond, and the chemical bonding effect is enhanced; again, since the -OH on the surface of PF is negatively charged, it attracts Ca 2+ through electrostatic effect to form "ion adsorption layer", which promotes the heterogeneous nucleation of C-(A)-S-H gel on its surface to form a transition zone with low porosity, effectively inhibiting the propagation of microcracks, and forming a uniform interface structure; finally, the flexible PF ensures the effective transmission and release of tensile stress through good "bridging" effect, delaying the initiation and propagation of matrix microcracks, and improving the toughness and interfacial bonding properties of the material.

[0154] Example 13

[0155] An alkali-activated MK-BFS inorganic glue, the amount of each component is as follows: 18.0 parts of MK, 72.0 parts of BFS, 43.85 parts of water glass, 8.43 parts of NaOH, 13.68 parts of water, 5 parts of NA and 5 parts of WS mixture.

[0156] The preparation method of the above-mentioned alkali-activated MK-BFS inorganic glue, the steps are as follows:

[0157] (1) Preparation of alkaline activator: slowly inject NaOH with a density of 2.13 g / cm 3 into the water glass solution, continuously stir with a glass rod to obtain a compounded solution with a water glass modulus (SiO2 / Na2O) of 1.2 and a Na2O content of 10%, and then cool the prepared compounded solution to room temperature and stand for 24 h before use to obtain the alkaline activator.

[0158] (2) Add 18.0 parts of MK and 72.0 parts of BFS into a cement paste stirring pot, raise to a fixed position, and use a cement paste stirring machine with a model of NJ-160B to stir at a speed of 140 r / min for 3 min to make MK and BFS mix well. Low-speed stirring can avoid material splashing, and also can better ensure the uniform mixing of the two materials.

[0159] (3) Add 5 parts of WS to the mixed powder obtained in step (2), and use a cement paste stirring machine with a model of NJ-160B to stir at a speed of 140 r / min for 3 min, and after the materials are uniformly mixed, the mixed material is obtained; this process utilizes mechanical stirring to effectively realize the physical filling effect of WS, reduce the porosity, and improve the matrix density.

[0160] (4) 5 parts of NA and 13.68 parts of water were added into a beaker, and an ultrasonic disperser with model number KH2200B was used for ultrasonic dispersion for 20 minutes to obtain a uniform NA suspension. Ultrasonic treatment can quickly and uniformly disperse nanoparticles, effectively avoid particle agglomeration, and improve the dispersity and stability of NA; if the ultrasonic treatment time is too short, the dispersion is insufficient, and if the time is too long, secondary agglomeration is easily induced. The addition of an appropriate amount of water is conducive to the uniform dispersion of the powdered NA, and can also reasonably adjust the fluidity of the prepared inorganic glue to ensure its bonding effect.

[0161] (5) The NA suspension prepared in step (4) was injected into the mixed powder obtained in step (3), and a cement paste stirrer with model number NJ-160B was used for stirring at a speed of 140 r / min for 3 minutes, and after the materials were uniformly mixed, a mixture was obtained. During the contact between the prepared NA suspension and the mixture, physical filling occurs, and based on the micro-size effect, the NA is well filled and embedded in the micro-pores.

[0162] (6) 52.28 parts of the alkaline activator prepared in step (1) was injected into the mixture obtained in step (5), and a cement paste stirrer with model number NJ-160B was used for stirring at a speed of 140 r / min for 1 minute to preliminarily wet and disperse the MK and BFS particles, so as to ensure sufficient contact between the mixed solution and the particles, prevent the splashing of the activator and water, reduce internal bubbles, and avoid local clumping; then, the cement paste stirrer was started to stir at a speed of 285 r / min for 2 minutes to completely disperse the particles, further mix the materials uniformly, accelerate the system reaction, improve the fluidity, and shorten the total stirring time, and thus a MK-BFS inorganic glue modified by the addition of NA and WS was obtained.

[0163] This embodiment fully utilizes the NA amorphous region regulation and interface densification, surface effect and chemical bonding, crack arrest, and ion migration and reaction promotion, as well as the WS mechanical interlocking effect, promotion of gel formation, induced adsorption nucleation, and crack bridging and other interface bonding enhancement effects, and through the reasonable complex addition of the two, the bonding performance of the inorganic glue is effectively synergistically enhanced.

[0164] Example 14

[0165] An alkaline-activated MK-BFS inorganic glue, the dosages of the components are as follows: 18.9 parts of MK, 75.6 parts of BFS, 43.85 parts of water glass, 8.43 parts of NaOH, 13.68 parts of water, 5 parts of NA, and 0.5 parts of PF mixture.

[0166] The preparation method of the above-mentioned alkaline-activated MK-BFS inorganic glue, and the steps are as follows:

[0167] (1) Preparation of alkaline activator: slowly inject NaOH with a density of 2.13 g / cm3into the water glass solution, continuously stir with a glass rod to obtain a complex solution with a water glass modulus (SiO2 / Na2O) of 1.2 and a Na2O content of 10%, place the prepared complex solution in a beaker, cool to room temperature and stand for 24 h, then obtain the alkaline activator. 3

[0168] (2) Add 18.9 parts of MK and 75.6 parts of BFS into a cement paste stirring pot, raise to a fixed position, and stir at a speed of 140 r / min for 3 min with a cement paste stirring machine of model NJ-160B to make MK and BFS fully mixed. Low-speed stirring can avoid material splashing, and also can better ensure uniform mixing of the two materials.

[0169] (3) Add 0.5 parts of PF to 52.28 parts of the alkaline activator prepared in step (1), and fully stir to obtain a mixed solution; this process occurs physical combination, through mechanical stirring, PF and the alkaline activator are fully contacted, the PF surface slightly swells in the alkaline environment, which leads to the increase of the surface roughness, which is conducive to the combination of the gel formed in the system to form a physical interlocking structure.

[0170] (4) Add 5 parts of NA and 13.68 parts of water into a beaker, and ultrasonic disperse for 20 min with an ultrasonic disperser of model KH2200B to obtain a uniform NA suspension. Ultrasonic treatment can quickly and uniformly disperse nanoparticles, and also can effectively avoid particle agglomeration, improve the dispersibility and stability of NA; ultrasonic treatment for 20 min is not enough, and for too long time will easily cause secondary agglomeration. The addition of an appropriate amount of water is conducive to the uniform dispersion of powdered NA, and also can reasonably adjust the fluidity of the inorganic glue to ensure its bonding effect.

[0171] (5) Pour the mixed liquid prepared in step (3) and the NA suspension prepared in step (4) into the mixed powder obtained in step (2), and stir at a speed of 140 r / min for 3 min with a cement paste stirring machine of model NJ-160B, and then obtain the mixed material after the materials are uniformly mixed. The wetting and dispersion of MK and BFS particles are ensured, the mixing of the mixed liquid and the particles is fully contacted, low-speed stirring in the early stage can prevent the splashing of the activator and water, and also can reduce internal bubbles and avoid local clumping. At the same time, the prepared NA suspension is physically filled during the contact with the mixed material, and based on the micro-size effect, the NA is well filled and embedded in the micro-pores. Then, start the cement paste stirring machine at a speed of 285 r / min for 2 min to completely disperse the particles, further mix the materials uniformly, accelerate the system reaction and improve the fluidity, and shorten the total stirring time, and then obtain the alkaline activated MK-BFS inorganic glue modified by adding NA and PF.​

[0172] The present embodiment takes full advantage of the above-mentioned NA amorphous zone regulation and interface densification, surface effect and chemical bonding, crack arrest, and ion migration and reaction promotion and PF physical bonding and mechanical anchoring, chemical bonding, interface transition zone optimization, stress transfer and bridging effect interface bonding enhancement, and effectively realizes the synergistic enhancement of the bonding performance of the inorganic glue through reasonable complex doping of the two.

[0173] Example 15

[0174] An alkali-activated MK-BFS inorganic glue, the amount of each component is as follows: 18.8 parts of MK, 75.2 parts of BFS, 43.85 parts of water glass, 8.43 parts of NaOH, 13.68 parts of water, 5 parts of WS and 1.0 parts of NS mixture.

[0175] (1) Preparation of alkaline activator: slowly inject NaOH with a density of 2.13 g / cm 3 into the water glass solution, continuously stir with a glass rod to obtain a compounded solution with a water glass modulus (SiO2 / Na2O) of 1.2 and a Na2O content of 10%, place the prepared compounded solution in a beaker, cool to room temperature and stand for 24 h, then obtain the alkaline activator.

[0176] (2) Add 18.8 parts of MK and 75.2 parts of BFS to a cement paste stirring pot, raise to a fixed position, and stir at a speed of 140 r / min for 3 min using a cement paste stirring machine of NJ-160B type to mix MK and BFS thoroughly. Low-speed stirring can avoid material splashing, and also can better ensure uniform mixing of the two materials.

[0177] (3) Add 5 parts of WS to the mixed powder obtained in step (2), and stir at a speed of 140 r / min for 3 min using a cement paste stirring machine of NJ-160B type, and after the materials are uniformly mixed, obtain the mixed material; this process utilizes mechanical stirring to effectively realize the physical filling effect of WS, reduce porosity, and improve the density of the matrix.

[0178] (4) Add 1 part of NS and 13.68 parts of water to a beaker, and ultrasonically disperse for 20 min using an ultrasonic disperser of KH2200B type to obtain a uniform NS suspension. Ultrasonic treatment can quickly and uniformly disperse the nanoparticles, effectively avoid particle agglomeration, and improve the dispersibility and stability of NS; ultrasonic treatment for 20 min is not enough for dispersion, and ultrasonic treatment for too long time can easily cause secondary agglomeration. The addition of an appropriate amount of water is beneficial to the uniform dispersion of powdered NS, and also can reasonably adjust the fluidity of the inorganic glue to ensure its bonding effect.

[0179] (5) Injecting the NS suspension prepared in step (4) into the mixed powder obtained in step (3), using a cement paste mixer of model NJ-160B to stir at a speed of 140 r / min for 3 min, until the materials are uniformly mixed, to obtain a mixture. During the contact between the prepared NS suspension and the mixture, physical filling occurs, and based on the micro-size effect, the NS is well filled and embedded in the micro-pores.

[0180] (6) Injecting 52.28 parts of the alkaline activator prepared in step (1) into the mixture obtained in step (5), using a cement paste mixer of model NJ-160B to stir at a speed of 140 r / min for 1 min to preliminarily wet and disperse the MK and BFS particles, to ensure sufficient contact between the mixed solution and the particles, and to prevent the activator and water from splashing out, and to reduce internal bubbles and avoid local clumping; then, starting the cement paste mixer to stir at a speed of 285 r / min for 2 min to completely disperse the particles, to further uniformly mix the materials, to accelerate the system reaction and improve the fluidity, and to shorten the total stirring time, to obtain the inorganic glue of the alkaline-activated MK-BFS modified by the incorporation of NS and WS.

[0181] This embodiment fully utilizes the physical filling, nucleation site, surface characteristics of NS, the mechanical interlocking effect of WS, the interface adhesion enhancement effect of promoting gel generation, inducing adsorption nucleation, and crack bridging, and through the reasonable compounding of the two, the synergistic enhancement of the bonding performance of the inorganic glue is effectively realized.

[0182] Comparative Example 1

[0183] An alkaline-activated MK-BFS inorganic glue, the amounts of the components are as follows in terms of mass ratio:

[0184] 20 parts of MK, 80 parts of BFS, 43.85 parts of water glass, 8.43 parts of NaOH, and 13.68 parts of water.

[0185] The preparation method of the above alkaline-activated MK-BFS inorganic glue, the steps are as follows:

[0186] (1) Preparation of alkaline activator: slowly injecting NaOH with a density of 2.13 g / cm 3 into the water glass solution, using a glass rod to continuously stir to obtain a compounded solution with a water glass modulus (SiO2 / Na2O) of 1.2 and a Na2O content of 10%, placing the prepared compounded solution in a beaker, cooling to room temperature and standing for 24 h to obtain an alkaline activator.

[0187] (2) 20 parts of MK and 80 parts of BFS were added into a cement paste stirring pot, which was raised to a fixed position, and a cement paste stirring machine with a model of NJ-160B was used to stir at a speed of 140 r / min for 3 min, so that the MK and BFS were fully mixed. Low-speed stirring can avoid material splashing, and can also better ensure uniform mixing of the two materials.

[0188] (3) 52.28 parts of the alkaline activator and 13.68 parts of water prepared in step (1) were injected into 100 parts of the mixed powder obtained in step (2), and a cement paste stirring machine with a model of NJ-160B was used to stir at a speed of 140 r / min for 1 min, so that the MK and BFS particles were preliminarily wetted and dispersed, and the mixing liquid and the particles were fully contacted. Low-speed stirring in the early stage can prevent the splashing of the activator and water, and can also reduce internal bubbles and avoid local clumping. Then, the cement paste stirring machine was started to stir at a speed of 285 r / min for 2 min, so that the particles were thoroughly dispersed, the material mixing was further uniform, the system reaction was accelerated, the fluidity was improved, and the total stirring time was shortened, and thus the alkaline activated MK-BFS inorganic glue was obtained.

[0189] The alkaline activated MK-BFS inorganic glue prepared in the above examples 1-15 and comparative example 1 was subjected to interface bonding strength test and compressive strength test, and the test results are shown in Table 9. As can be seen from the table, by adding NA, NS, WS and PF modifying substances, the interface bonding strength and compressive strength of the alkaline activated MK-BFS inorganic glue are improved from the aspects of amorphous zone regulation and interface densification, surface effect and chemical bonding, ion migration and reaction promotion, physical filling and mechanical interlocking, induced adsorption nucleation and crack bridging, and the interface bonding strength and compressive strength of the alkaline activated MK-BFS inorganic glue in example 13 are best improved.

[0190] Table 9 Comparison of test results of alkaline activated MK-BFS inorganic glue prepared in examples 1-15 and comparative example 1

[0191]

[0192] As can be seen from the comparison of the above examples 1-12 and examples 13-15, compared with the separate addition of modified materials, the reasonable mixing of different modified materials can more obviously improve the interface bonding strength and compressive strength of the alkaline activated MK-BFS inorganic glue, which is mainly due to the synergistic complementary effect of different modified materials, and the reasonable mixing can better improve the interface compatibility. At the same time, the mixing of modified materials can form a more complex transition layer at the interface, increase the number of mechanical engagement points and chemical bonds, and cause the physical entanglement and chemical crosslinking to work together to enhance. In addition, the modulus difference of different modified materials can also better disperse the interface stress concentration and reduce the risk of matrix cracking.

Claims

1. An alkali-activated MK-BFS inorganic glue, characterized in that, The solid component comprises 18.6-20 parts of MK, 74.4-80 parts of BFS and 0.3-7 parts of modified material; the liquid component comprises 41.82-62.74 parts of alkaline activator and 9.68-13.68 parts of water; the ratio of the solid component to the liquid component is 1.42-1.62:1; The alkaline activator is a compound solution obtained by mixing NaOH and water glass solution; the mass ratio of the NaOH to the water glass solution is 0.16-0.25:1; The modified material is PVA fiber with a length of 2-4 mm; The PVA fiber accounts for 0.3-0.7% of the solid component.

2. The alkali-activated MK-BFS inorganic glue according to claim 1, characterized in that, The modified material is a mixture of PVA fiber with a length of 2-4 mm and nano-Al2O3; The nano-Al2O3 accounts for 5% of the solid component; the PVA fiber with a length of 2-4 mm accounts for 0.5% of the solid component.

3. Alkali-activated MK-BFS inorganic glue according to claim 1 or 2, characterized in that, The liquid component comprises 52.28 parts of alkaline activator and 13.68 parts of water; in the alkaline activator, the mass ratio of the NaOH to the water glass solution is 8.43:43.

85.

4. The alkali-activated MK-BFS inorganic glue according to claim 1 or 2, characterized in that, The MK has a particle size range of 0.36-66.9 μm, a specific surface area of 188.4-220.6 m 2 2 / g; the BFS has a particle size range of 0.31-76.0 μm, a specific surface area of 208.5-235.9 m 2 2 / g.

5. The alkali-activated MK-BFS inorganic glue according to claim 1 or 2, characterized in that, In the alkaline activator, the modulus of the water glass is 1.0-1.4, and the Na2O content is 8.0-12.0%.

6. The alkali-activated MK-BFS inorganic glue according to claim 2, characterized in that, The nano-Al2O3 has a particle size of 20-30 nm and a specific surface area of 150-200 m 2 / g.

7. The alkali-activated MK-BFS inorganic glue according to claim 1 or 2, characterized in that, The PVA fiber has a diameter of 12-16 μm and a density of 1.1-1.3 g / cm 3 .

8. The method of claim 1 to 7, wherein the method is characterized by, The steps are as follows: S1: inject NaOH into water glass solution, stir to obtain a compound solution with a modulus of 1.0-1.4 and a Na2O content of 8-12%, and then stand for 24 h to obtain an alkaline activator; S2: add 18.6-20 parts of MK and 74.4-80 parts of BFS into a cement paste stirring pot, dry mix for 3 min to obtain a mixed powder; S3: add modified material into the mixed powder obtained in S2 according to the proportion, stir to obtain a mixture; S4: inject 41.82-62.74 parts of the alkaline activator prepared in S1 and 9.68-13.68 parts of water into 100 parts of the mixture obtained in S3, slowly stir and then fast stir to obtain an alkaline-activated MK-BFS inorganic glue.

9. Application of the alkaline-activated MK-BFS inorganic glue according to any one of claims 1-7 in reinforcing concrete.

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