Tunnel lining concrete and preparation method thereof

Abstract

The invention relates to the technical field of concrete, and particularly discloses tunnel lining concrete and a preparation method thereof. The tunnel lining concrete is prepared from the following raw materials in parts by mass: 320 to 380 parts of Portland cement, 60 to 100 parts of fly ash, 40 to 80 parts of superfine slag powder, 950 to 1100 parts of coarse aggregate, 750 to 850 parts of fine aggregate, 30 to 55 parts of expanding agent, 0.8 to 1.2 parts of polypropylene short fiber, 4.5 to 6.5 parts of polycarboxylate superplasticizer and 150 to 170 parts of water, the expanding agent is prepared from calcium aluminosilicate clinker, sodium fluoroaluminate and water through double decomposition reaction. The expanding agent is prepared from the calcium aluminosilicate clinker, sodium fluoroaluminate and water through a double decomposition reaction, the main product of the expanding agent is calcium aluminofluorosilicate expanding crystals, meanwhile, generated sodium hydroxide and aluminum hydroxide serve as beneficial by-products, concrete shrinkage can be compensated in a staged mode, the pore structure can be optimized, and the crack resistance, impermeability and durability of concrete can be synergistically improved; the compatibility with all the raw materials is good, and the problem that the tunnel lining concrete is poor in anti-cracking and anti-permeability synergism can be solved.

Description

Technical Field

[0001] This application relates to the field of concrete technology, and more specifically, to a tunnel lining concrete and a method for preparing the same. Background Technology

[0002] As the core load-bearing and protective component of the underground tunnel structure, the tunnel lining concrete directly bears complex loads such as surrounding rock pressure, ground stress, and groundwater pressure. At the same time, it is used for a long time in the harsh underground environment of humid, corrosive media and temperature fluctuations. Its mechanical properties, crack resistance, impermeability, durability and construction adaptability directly affect the safety and service life of the tunnel structure.

[0003] Crack resistance and impermeability are the two most critical properties of tunnel lining concrete, and they are highly correlated and synergistic: crack resistance is the foundation of impermeability. Once cracks appear in concrete, no matter how dense the pore structure, the cracks become channels for the rapid intrusion of groundwater and corrosive ions, directly leading to the failure of impermeability. Conversely, impermeability is the long-term guarantee of crack resistance. Good impermeability can prevent groundwater from softening the concrete and corrosive ions from corroding the reinforcing steel, avoiding the formation of rust-induced cracks and maintaining the overall crack resistance of the structure. Especially in Shaanxi, Gansu, Ningxia, and Northwest China, tunnels often traverse loess soft rock, high-pressure aquifers, and saline soil areas. Uneven deformation of the surrounding rock in loess soft rock areas can easily cause cracks in the lining concrete structure, while high-pressure groundwater places stringent requirements on the impermeability of concrete. Therefore, the synergistic improvement of the crack resistance and impermeability of concrete is particularly important.

[0004] In the prior art, patent application CN105503076A discloses a high-performance impermeable concrete for tunnels and its preparation method. The high-performance impermeable concrete for tunnels is made from the following components by mass fraction: 69-75 parts ordinary silicate cement, 12-15 parts desulfurized gypsum, 10-12 parts oil shale waste, 8-10 parts quartz sand, 8-10 parts kaolin, 6-8 parts serpentine powder, 0.8-1 parts polypropylene short fiber, 3-4 parts hydrogenated rosin powder, 4-5 parts hydroxypropyl guar gum, 36-40 parts water, 1.5-2 parts barium petroleum sulfonate, and 0 parts polydimethyldiallyl ammonium chloride. The application document uses polypropylene short fibers to achieve toughening and crack resistance, but does not include components to compensate for concrete volume shrinkage. This fails to effectively compensate for the drying and thermal shrinkage deformations that occur during the hydration and hardening process of concrete, resulting in poor concrete volume stability. Under the uneven deformation of the surrounding rock in loess soft rock tunnels, the concrete is prone to early plastic cracks, drying shrinkage cracks, and internal through-cracks, leading to insufficient crack resistance. Furthermore, the formation of cracks directly damages the internal pore structure of the concrete, significantly reducing its impermeability and failing to achieve a synergistic improvement in crack resistance and impermeability. Summary of the Invention

[0005] To address the problems of insufficient crack resistance and poor synergy between crack resistance and impermeability in existing tunnel lining concrete, this application provides a tunnel lining concrete and its preparation method.

[0006] In a first aspect, this application provides a tunnel lining concrete, employing the following technical solution: A tunnel lining concrete comprises the following raw materials in parts by weight: 320-380 parts silicate cement, 60-100 parts fly ash, 40-80 parts slag powder, 950-1100 parts coarse aggregate, 750-850 parts fine aggregate, 30-55 parts expansion agent, 0.8-1.2 parts polypropylene short fiber, 4.5-6.5 parts polycarboxylate superplasticizer, and 150-170 parts water; The expanding agent is prepared by a metathesis reaction of calcium aluminosilicate clinker, sodium fluoroaluminate, and water.

[0007] By adopting the above technical solution, an expansive agent prepared by metathesis reaction of calcium aluminosilicate clinker, sodium fluoroaluminate, and water produces calcium aluminosilicate expanded crystals as its main product. The accompanying sodium hydroxide and aluminum hydroxide, as beneficial byproducts, play multiple beneficial roles in tunnel lining concrete: When mixed into concrete, this expansive agent can achieve volume compensation in stages. In the early stage, it slowly initiates crystal growth, compensating for plastic shrinkage and initial drying shrinkage of concrete, and inhibiting the formation of early microcracks. In the middle stage, rapid crystal growth forms a needle-like network structure, continuously compensating for drying shrinkage and thermal shrinkage deformation of concrete, while simultaneously optimizing the microporous structure of concrete, improving density, and enhancing impermeability to resist high temperatures. Water pressure reduces groundwater infiltration; subsequent crystal growth tends to stabilize without shrinkage rebound, continuously compensating for long-term concrete drying shrinkage and ensuring long-term volume stability of the lining; among them, the reaction byproduct sodium hydroxide can increase the alkalinity of the concrete system, assisting in promoting cement hydration and accelerating early strength development, aluminum hydroxide can fill the micropores of concrete, further enhancing impermeability, and the fluorine element contained in the crystals can also form a corrosion-resistant protective layer, inhibiting corrosion ion erosion, and synergistically improving the strength and durability of concrete; in addition, this expansive agent has excellent compatibility with various concrete raw materials, does not affect pumping performance, and can effectively solve the problems of easy cracking and poor synergy between crack resistance and impermeability in tunnel lining concrete.

[0008] Preferably, the preparation method of the expanding agent is as follows: 70-80 parts by weight of calcium aluminosilicate clinker and 20-30 parts by weight of sodium fluoroaluminate are added to 5-8 parts by weight of deionized water, and the mixture is reacted at room temperature for 2-3 hours to obtain the expanding agent.

[0009] By adopting the above technical solution, the preparation method of this expansion agent is scientifically formulated and the reaction conditions are reasonable, which can ensure that the reaction proceeds fully and generate high-purity, stable expansion crystals. At the same time, it simplifies the preparation process, reduces production costs, and avoids problems such as waste of raw materials and incomplete reaction, laying the foundation for its subsequent good expansion compensation and crack resistance and impermeability in tunnel lining concrete.

[0010] Preferably, the preparation method of the expanding agent is as follows: 70-80 parts by weight of calcium aluminosilicate clinker, 20-30 parts by weight of sodium fluoroaluminate and 0.5-1 parts by weight of γ-aminopropyltriethoxysilane are added to 5-8 parts by weight of deionized water and reacted at room temperature for 2-3 hours to obtain the expanding agent.

[0011] By adopting the above technical solution, adding γ-aminopropyltriethoxysilane (KH-550) during the preparation of the expanding agent does not interfere with the core metathesis reaction of calcium aluminosilicate clinker and sodium fluoroaluminate, nor with the formation of core expanding crystals. This significantly improves the dispersibility of the expanding agent, prevents particle agglomeration, ensures uniform dispersion when mixed into concrete, and guarantees the uniformity of expansion compensation. At the same time, it strengthens the adhesion between the expanding agent and various concrete components, synergistically improves the concrete strength, and forms a protective film on the surface of the expanding crystals, improving the storage stability, long-term water resistance, and durability of the expanding effect of the expanding agent. In synergy with the original reaction byproducts, it further optimizes the microporous structure of concrete, enhances its impermeability and corrosion resistance, better adapts to the complex geological conditions in the Shaanxi-Gansu-Ningxia region, and extends the service life of tunnel linings.

[0012] Preferably, the preparation method of the expanding agent is as follows: 70-80 parts by weight of calcium aluminosilicate clinker, 20-30 parts by weight of sodium fluoroaluminate and 0.3-0.8 parts by weight of nano-silica are added to 5-8 parts by weight of deionized water and reacted at room temperature for 2-3 hours to obtain the expanding agent.

[0013] By adopting the above technical solution, adding nano-silica during the preparation of the expanding agent can fill the micropores inside the expanding crystals and at the interface without affecting the in-situ reaction between calcium aluminosilicate clinker and sodium fluoroaluminate, thereby improving the density and uniformity of the expanding agent structure. At the same time, it enhances the interfacial bonding force between the expanding agent and the concrete matrix, improves dispersibility, and avoids agglomeration and uneven local expansion. Nano-silica can also synergistically enhance the matrix strength with concrete hydration products, further improve the concrete's impermeability and volume stability, make expansion compensation more stable and durable, and significantly improve the long-term crack resistance and erosion resistance of tunnel lining concrete.

[0014] Preferably, the preparation method of the expanding agent is as follows: 70-80 parts by weight of calcium aluminosilicate clinker, 20-30 parts by weight of sodium fluoroaluminate, 0.3-0.8 parts by weight of nano-silica and 0.5-1 parts by weight of γ-aminopropyltriethoxysilane are added to 5-8 parts by weight of deionized water and reacted at room temperature for 2-3 hours to obtain the expanding agent.

[0015] By adopting the above technical solution, nano-silica and γ-aminopropyltriethoxysilane (KH-550) are introduced simultaneously during the preparation of the expansive agent. The two can produce a synergistic optimization effect: nano-silica can fill the micropores of the crystal, increase the density of the expansive agent and enhance the strength of the concrete matrix, while KH-550 can improve the dispersion uniformity of the expansive agent, strengthen the interfacial bond with cement paste and improve long-term stability. The synergy between the two makes the expansion process of the expansive agent more stable and its compatibility with concrete better, further improving the crack resistance, impermeability and durability of tunnel lining concrete.

[0016] Preferably, the raw material further includes 8-15 parts by weight of organic bentonite.

[0017] By adopting the above technical solution, organic bentonite is introduced into the concrete system, which forms a significant synergistic effect with the expansive agent: the expansive agent compensates for concrete shrinkage and inhibits cracking through in-situ generated expansive crystals, while organic bentonite fills micropores and blocks water seepage channels through its own layered structure. The combination of the two can further reduce the porosity and permeability of concrete; at the same time, organic bentonite can improve the cohesiveness of the paste and reduce plastic cracks. Together with the volume compensation effect of the expansive agent and the crack-blocking effect of polypropylene fibers, it forms a three-dimensional crack-resistant system, which significantly improves the early crack resistance, long-term impermeability and structural density of concrete.

[0018] Preferably, the organic bentonite is obtained by modifying sodium-based bentonite with γ-polyglutamic acid and hexadecyltrimethylammonium bromide.

[0019] By adopting the above technical solution, the organic bentonite modified with γ-polyglutamic acid and hexadecyltrimethylammonium bromide has a more dispersed, stronger adsorption and barrier structure, and can interpenetrate and overlap with the calcium aluminofluorosilicate crystals generated by the expansion agent, further densifying the concrete pore structure and blocking water seepage channels. The modified bentonite can also improve the water retention and cohesiveness of the slurry, reduce early plastic cracking, and complement the volume compensation effect of the expansion agent, achieving a triple synergy of expansion crack resistance, structural crack prevention and interface densification, significantly improving the impermeability and crack resistance of tunnel lining concrete.

[0020] Preferably, the mass ratio of γ-polyglutamic acid to hexadecyltrimethylammonium bromide is 1:(3-5).

[0021] By adopting the above technical solution, the above ratio enables γ-polyglutamic acid and hexadecyltrimethylammonium bromide to fully exert their synergistic modification effect, so that bentonite can obtain a suitable organic intercalation effect and dispersibility. This ensures that the bentonite layers are fully delaminated, and the concrete strength is not affected by excessive organic components. The modified bentonite has better compatibility with the expansive agent crystals, which can effectively improve the compactness, impermeability and crack resistance of concrete. The synergistic effect of the two is stable and significant.

[0022] Preferably, the organic bentonite is sodium-based bentonite that has been modified by a composite of γ-polyglutamic acid and hexadecyltrimethylammonium bromide, and then subjected to ultrasonic activation treatment; The mass ratio of γ-polyglutamic acid to hexadecyltrimethylammonium bromide is 1:(3-5). The ultrasonic activation treatment is performed at a power of 120-200W, a temperature of 40-60℃, and a time of 30-60min.

[0023] By adopting the above technical solution, ultrasonic activation can significantly promote the intercalation and dispersion of the modifier between bentonite layers, enabling the layers to fully peel off and the structure to become more loose and porous. This interacts with the calcium aluminofluorosilicate crystals generated by the expansive agent, greatly improving the compactness and impermeability of concrete. At the same time, the water retention, thickening, and plastic crack reduction effects of the modified bentonite are further enhanced. Together with the volume compensation effect of the expansive agent and the crack-resistant effect of the polypropylene fiber, a three-dimensional synergistic system is formed, significantly improving the early crack resistance and long-term durability of concrete.

[0024] Secondly, this application provides a method for preparing tunnel lining concrete, which adopts the following technical solution: A method for preparing tunnel lining concrete includes the following steps: According to the formula, silicate cement, fly ash, slag powder, coarse aggregate, fine aggregate, and polypropylene short fiber are mixed evenly, and then the remaining raw materials are added and stirred to obtain tunnel lining concrete.

[0025] The above technical solution provides a simple and feasible preparation method that allows for thorough mixing and synergistic effects of various raw materials. This effectively ensures the optimized effects of components such as the expanding agent and modified organic bentonite, significantly improving the crack resistance, impermeability, and durability of tunnel lining concrete.

[0026] In summary, this application has the following beneficial effects: 1. The expansion agent of this application is obtained by metathesis reaction between calcium aluminosilicate clinker and sodium fluoroaluminate to obtain calcium aluminosilicate expanded crystals, sodium hydroxide and aluminum hydroxide. It can compensate for concrete shrinkage in stages, optimize pore structure, and synergistically improve the crack resistance, impermeability and durability of concrete. It also has good compatibility with each raw material and can solve the problem of poor synergy between crack resistance and impermeability of tunnel lining concrete.

[0027] 2. This application improves the dispersibility, density and interfacial bonding of the expansive agent by introducing nano-silica and / or γ-aminopropyltriethoxysilane into the expansive agent without affecting the core reaction, thereby synergistically optimizing the crack resistance, impermeability and durability of concrete, and making the expansion compensation more stable and durable.

[0028] 3. This application introduces organic bentonite into the concrete system, which can form a synergistic effect with the expansion agent and work with polypropylene fibers to construct a three-dimensional crack-resistant system, effectively reducing the porosity of concrete and improving its early crack resistance, long-term impermeability and structural density. Detailed Implementation

[0029] The present application will be further described in detail below with reference to the embodiments.

[0030] Unless otherwise specified, the raw materials used in the preparation examples, embodiments, and comparative examples of this application are all commercially available.

[0031] Preparation Examples 1-5 Expanding Agent Preparation Example 1 This preparation example discloses a method for preparing an expanding agent, specifically including the following steps: 75 kg of calcium aluminosilicate clinker and 25 kg of sodium fluoroaluminate were stirred at 320 r / min for 18 min. 6.5 kg of deionized water was added dropwise at a rate of 65 mL / min. The stirring speed was adjusted to 190 r / min at room temperature, and the reaction was continued for 2.5 h. After the reaction was completed, the product was placed in a vacuum drying oven and dried at 82 °C for 1.5 h. After pulverizing, it was passed through a 100-mesh sieve to obtain the expanding agent.

[0032] Preparation Example 2 This preparation example discloses a method for preparing an expanding agent, specifically including the following steps: 75 kg of calcium aluminosilicate clinker, 25 kg of sodium fluoroaluminate, and 0.8 kg of γ-aminopropyltriethoxysilane (KH-550) were stirred at 320 r / min for 18 min. 6.5 kg of deionized water was added dropwise at a rate of 65 mL / min. The stirring speed was adjusted to 190 r / min at room temperature, and the reaction was continued for 2.5 h. After the reaction was completed, the product was placed in a vacuum drying oven and dried at 82 °C for 1.5 h. After pulverizing, the product was passed through a 100-mesh sieve to obtain the expanding agent.

[0033] Preparation Example 3 This preparation example discloses a method for preparing an expanding agent, specifically including the following steps: 75 kg of calcium aluminosilicate clinker, 25 kg of sodium fluoroaluminate, and 0.5 kg of nano-silica were stirred at 320 r / min for 18 min. 6.5 kg of deionized water was added dropwise at a rate of 65 mL / min. The stirring speed was adjusted to 190 r / min at room temperature, and the reaction was continued for 2.5 h. After the reaction was completed, the product was placed in a vacuum drying oven and dried at 82 °C for 1.5 h. After pulverizing, the product was passed through a 100-mesh sieve to obtain the expanding agent.

[0034] Preparation Example 4 This preparation example discloses a method for preparing an expanding agent, specifically including the following steps: 75 kg of calcium aluminosilicate clinker, 25 kg of sodium fluoroaluminate, 0.8 kg of γ-aminopropyltriethoxysilane (KH-550), and 0.5 kg of nano-silica were stirred at 320 r / min for 18 min. 6.5 kg of deionized water was added dropwise at a rate of 65 mL / min. The stirring speed was adjusted to 190 r / min at room temperature, and the reaction was continued for 2.5 h. After the reaction was completed, the product was placed in a vacuum drying oven and dried at 82 °C for 1.5 h. After pulverizing, the product was passed through a 100-mesh sieve to obtain the expanding agent.

[0035] Preparation Example 5 This preparation example discloses a method for preparing an expanding agent, specifically including the following steps: 70 kg of calcium aluminosilicate clinker, 30 kg of sodium fluoroaluminate, 0.5 kg of γ-aminopropyltriethoxysilane (KH-550), and 0.3 kg of nano-silica were stirred at 320 r / min for 18 min. Then, 5 kg of deionized water was added dropwise at a rate of 65 mL / min. The stirring speed was adjusted to 190 r / min at room temperature, and the reaction was continued for 2.5 h. After the reaction was completed, the product was placed in a vacuum drying oven and dried at 82 °C for 1.5 h. After pulverizing, the product was passed through a 100-mesh sieve to obtain the expanding agent.

[0036] Preparation Example 6 This preparation example discloses a method for preparing an expanding agent, specifically including the following steps: 80 kg of calcium aluminosilicate clinker, 20 kg of sodium fluoroaluminate, 1 kg of γ-aminopropyltriethoxysilane (KH-550), and 0.8 kg of nano-silica were stirred at 320 r / min for 18 min. 8 kg of deionized water was added dropwise at a rate of 65 mL / min. The stirring speed was adjusted to 190 r / min at room temperature, and the reaction was continued for 2.5 h. After the reaction was completed, the product was placed in a vacuum drying oven and dried at 82 °C for 1.5 h. After pulverizing, the product was passed through a 100-mesh sieve to obtain the expanding agent.

[0037] Preparation Example 7-10: Organobentonite Preparation Example 7 This preparation example discloses a method for preparing organic bentonite, which specifically includes the following steps: At a stirring speed of 300 r / min, 2 kg of γ-polyglutamic acid and 8 kg of hexadecyltrimethylammonium bromide were added to 100 kg of sodium bentonite and stirred for 25 min. Then, 30 kg of deionized water was added, the stirring speed was adjusted to 180 r / min, and stirring was continued for 60 min at room temperature. After the reaction was completed, the product was placed in a vacuum drying oven and dried at 85 °C for 2 h. After pulverizing, it was passed through a 120 mesh sieve to obtain organobentonite.

[0038] Preparation Example 8 This preparation example discloses a method for preparing organic bentonite, which specifically includes the following steps: At a stirring speed of 300 r / min, 2 kg of γ-polyglutamic acid and 8 kg of hexadecyltrimethylammonium bromide were added to 100 kg of sodium bentonite and stirred for 25 min. Then, 30 kg of deionized water was added, the stirring speed was adjusted to 180 r / min, and stirring was continued for 60 min at room temperature. After the reaction was completed, the product was ultrasonically treated at 160 W ultrasonic power and 50 °C for 45 min. The ultrasonically treated product was placed in a vacuum drying oven and dried at 85 °C for 2 h. After pulverization, it was passed through a 120 mesh sieve to obtain organic bentonite.

[0039] Preparation Example 9 This preparation example discloses a method for preparing organic bentonite, which specifically includes the following steps: At a stirring speed of 300 r / min, 2 kg of γ-polyglutamic acid and 6 kg of hexadecyltrimethylammonium bromide were added to 100 kg of sodium bentonite and stirred for 25 min. Then, 30 kg of deionized water was added, the stirring speed was adjusted to 180 r / min, and stirring was continued for 60 min at room temperature. After the reaction was completed, the product was ultrasonically treated at 120 W ultrasonic power and 40 °C for 60 min. The ultrasonically treated product was placed in a vacuum drying oven and dried at 85 °C for 2 h. After pulverization, it was passed through a 120 mesh sieve to obtain organobentonite.

[0040] Preparation Example 10 This preparation example discloses a method for preparing organic bentonite, which specifically includes the following steps: At a stirring speed of 300 r / min, 2 kg of γ-polyglutamic acid and 10 kg of hexadecyltrimethylammonium bromide were added to 100 kg of sodium bentonite and stirred for 25 min. Then, 30 kg of deionized water was added, the stirring speed was adjusted to 180 r / min, and stirring was continued for 60 min at room temperature. After the reaction was completed, the product was ultrasonically treated at 200 W ultrasonic power and 60 °C for 30 min. The ultrasonically treated product was placed in a vacuum drying oven and dried at 85 °C for 2 h. After pulverization, it was passed through a 120 mesh sieve to obtain organobentonite.

[0041] Example 1 This embodiment provides a tunnel lining concrete, comprising 350 kg of silicate cement (grade 42.5), 80 kg of fly ash (grade I), 60 kg of slag powder (grade S95), 1025 kg of coarse aggregate (5-31.5 mm continuously graded granite aggregate), 800 kg of fine aggregate (fineness modulus 2.4-2.7), 42.5 kg of expansion agent (obtained from Preparation Example 1), 1 kg of polypropylene short fiber (polypropylene monofilament fiber, length 6 mm, diameter 20 μm), 5.5 kg of polycarboxylate superplasticizer, and 160 kg of deionized water; This embodiment also provides a method for preparing the above-mentioned tunnel lining concrete, including the following steps: According to the above formula, first dilute the polycarboxylate superplasticizer with 5 kg of deionized water and set aside. Silicate cement, fly ash, slag powder, coarse aggregate, fine aggregate, and polypropylene short fibers are mixed at a stirring speed of 300 r / min for 15 min. Then, an expansion agent, diluted polycarboxylate superplasticizer, and the remaining deionized water are added, and the mixture is stirred at a stirring speed of 220 r / min for 10 min to obtain tunnel lining concrete.

[0042] Example 2 This embodiment provides a tunnel lining concrete, comprising 320 kg of silicate cement (grade 42.5), 60 kg of fly ash (grade I), 40 kg of slag powder (grade S95), 1100 kg of coarse aggregate (5-31.5 mm continuously graded granite aggregate), 850 kg of fine aggregate (fineness modulus 2.4-2.7), 55 kg of expansion agent (obtained from Preparation Example 1), 1.2 kg of polypropylene short fiber (polypropylene monofilament fiber, length 6 mm, diameter 20 μm), 11 kg of organic bentonite (commercially available product), 6.5 kg of polycarboxylate superplasticizer, and 150 kg of deionized water; This embodiment also provides a method for preparing the above-mentioned tunnel lining concrete, including the following steps: According to the above formula, first dilute the polycarboxylate superplasticizer with 5 kg of deionized water and set aside. Silicate cement, fly ash, slag powder, coarse aggregate, fine aggregate, and polypropylene short fibers are mixed at a stirring speed of 300 r / min for 15 min. Then, an expansion agent, diluted polycarboxylate superplasticizer, organic bentonite, and remaining deionized water are added, and the mixture is stirred at a stirring speed of 220 r / min for 10 min to obtain tunnel lining concrete.

[0043] Example 3 This embodiment is basically the same as Example 2, except that the expanding agent used is the one obtained in Preparation Example 2.

[0044] Example 4 This embodiment is basically the same as Example 2, except that the expanding agent used is the one obtained in Preparation Example 3.

[0045] Example 5 This embodiment is basically the same as Example 2, except that the expanding agent used is the one obtained in Preparation Example 4.

[0046] Example 6 This embodiment is basically the same as Example 5, except that the organic bentonite is the one obtained in Preparation Example 7.

[0047] Example 7 This embodiment is basically the same as Example 6, except that the organic bentonite is the one obtained in Preparation Example 8.

[0048] Example 8 This embodiment is basically the same as Embodiment 7, except that this embodiment provides a tunnel lining concrete, including 320 kg of silicate cement (42.5 grade), 60 kg of fly ash (Grade I), 40 kg of slag powder (S95 grade), 1100 kg of coarse aggregate (5-31.5 mm continuously graded granite aggregate), 850 kg of fine aggregate (fineness modulus 2.4-2.7), 55 kg of expansion agent (obtained from Preparation Example 5), 1.2 kg of polypropylene short fiber (polypropylene monofilament fiber, length 6 mm, diameter 20 μm), 8 kg of organic bentonite (obtained from Preparation Example 9), 6.5 kg of polycarboxylate superplasticizer, and 150 kg of deionized water.

[0049] Example 9 This embodiment is basically the same as Embodiment 7, except that this embodiment provides a tunnel lining concrete, including 380 kg of silicate cement (42.5 grade), 100 kg of fly ash (Grade I), 80 kg of slag powder (S95 grade), 950 kg of coarse aggregate (5-31.5 mm continuously graded granite aggregate), 750 kg of fine aggregate (fineness modulus 2.4-2.7), 35 kg of expansion agent (obtained from Preparation Example 6), 0.8 kg of polypropylene short fiber (polypropylene monofilament fiber, length 6 mm, diameter 20 μm), 15 kg of organic bentonite (obtained from Preparation Example 10), 4.5 kg of polycarboxylate superplasticizer, and 170 kg of deionized water.

[0050] Comparative Example 1 This comparative example is basically the same as Example 1, except that this comparative example provides a tunnel lining concrete, comprising 350 kg of silicate cement (42.5 grade), 80 kg of fly ash (Grade I), 60 kg of slag powder (S95 grade), 1025 kg of coarse aggregate (5-31.5 mm continuously graded granite aggregate), 800 kg of fine aggregate (fineness modulus 2.4-2.7), 1 kg of polypropylene short fiber (polypropylene monofilament fiber, length 6 mm, diameter 20 μm), 5.5 kg of polycarboxylate superplasticizer, and 160 kg of deionized water.

[0051] Testing standards: 1. Crack resistance: Referring to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" GB / T50082-2009, the early plastic cracking area and 28-day drying shrinkage of the concrete obtained in Examples 1-9 and Comparative Example 1 were tested; the 28-day drying shrinkage was tested using 100mm×100mm×515mm prism specimens, which were transferred to an environment with a temperature of 20±2℃ and a humidity of 60±5% after standard curing. The test results are recorded in Table 1.

[0052] 2. Impermeability: Referring to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" GB / T50082-2009, the impermeability grades of the concrete obtained in Examples 1-9 and Comparative Example 1 were tested, and the test results are recorded in Table 1.

[0053] 3. Mechanical properties: Referring to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" GB / T50081-2019, the 7-day and 28-day compressive strength and 28-day flexural strength of the concrete obtained in Examples 1-9 and Comparative Example 1 were tested, and the test results are recorded in Table 2.

[0054] 4. Corrosion resistance: A salt solution erosion test was conducted (immersion in 5wt% NaCl solution). Referring to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" GB / T50081-2019, the compressive strength of concrete obtained from Examples 1-9 and Comparative Example 1 after 28 days of salt solution immersion was tested, and the salt erosion loss rate was calculated by comparing it with the compressive strength after 28 days of standard curing. The test results are recorded in Table 2.

[0055] 5. Construction performance: Referring to the "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" GB / T50080-2016, the slump of the concrete obtained in Examples 1-9 and Comparative Example 1 was tested, and the test results are recorded in Table 2.

[0056] Table 1 Performance test data of tunnel lining concrete in Examples 1-9 and Comparative Example 1

[0057] Table 2 Performance test data of tunnel lining concrete in Examples 1-9 and Comparative Example 1

[0058] Referring to Table 1, and combining Example 1 and Comparative Example 1, it can be seen that, compared with Comparative Example 1, Example 1, due to the addition of a specifically prepared expansive agent, exhibits significantly improved crack resistance, effectively inhibiting the generation of early-stage plastic cracks in concrete, reducing long-term drying shrinkage deformation, and improving the volume stability of concrete. Simultaneously, the addition of the expansive agent optimizes the microporous structure of concrete, significantly enhancing its impermeability, effectively blocking seepage channels, and strengthening its durability. In terms of mechanical properties, Example 1 shows improved early and long-term strength, better meeting the load-bearing requirements of tunnel lining concrete. Both examples meet the requirements for tunnel pumping construction, but Example 1 exhibits better construction compatibility due to the good compatibility of the expansive agent with the raw materials. Regarding corrosion resistance, the salt erosion strength loss rate of Example 1 is significantly lower than that of Comparative Example 1. The fluorine element contained in the expansive agent can form a corrosion-resistant protective layer, synergistically enhancing impermeability, effectively blocking the intrusion of corrosive ions, reducing concrete strength loss, significantly improving the concrete's ability to resist corrosive ion erosion in saline soil areas, and further enhancing the concrete's durability.

[0059] Referring to Table 1 and combining Examples 1 and 2, it can be seen that, compared to Example 1, Example 2, due to the introduction of organic bentonite, forms a synergistic effect with the expansive agent, further improving the crack resistance of concrete, effectively reducing the generation of early plastic cracks, reducing long-term drying shrinkage deformation, and further optimizing the volume stability of concrete. Simultaneously, the layered structure of organic bentonite can fill the micropores of concrete and block seepage channels, complementing the effect of the expansive agent in optimizing the pore structure, significantly improving the impermeability and durability of concrete. In terms of mechanical properties, the addition of organic bentonite strengthens the interfacial bonding force between components, resulting in a certain improvement in both the early and long-term strength of concrete. Regarding corrosion resistance, the synergistic effect of organic bentonite and the expansive agent further blocks the penetration of corrosive ions, reducing the strength loss rate due to salt erosion in concrete. Compared to Example 1, the corrosion resistance of Example 2 is significantly improved, making it more suitable for the corrosive environment of the Shaanxi-Gansu-Ningxia region.

[0060] Referring to Table 1 and combining Examples 2 and 3, it can be seen that, compared to Example 2, Example 3 uses an expansive agent with added γ-aminopropyltriethoxysilane, which effectively improves the dispersibility of the expansive agent, avoids particle agglomeration, and ensures uniform dispersion of the expansive agent in the concrete, further improving the uniformity of expansion compensation, thereby enhancing the crack resistance of the concrete, reducing crack formation, and optimizing the volume stability of the concrete. Simultaneously, γ-aminopropyltriethoxysilane strengthens the bond between the expansive agent and various concrete components, and synergistically optimizes the microporous structure of the concrete with organic bentonite, improving the concrete's impermeability and durability, and better resisting groundwater infiltration and corrosive ion erosion. In terms of mechanical properties, the improved dispersibility of the expansive agent and the enhanced interfacial adhesion result in a certain improvement in both the early and long-term strength of the concrete. Regarding corrosion resistance, γ-aminopropyltriethoxysilane strengthens the interfacial bonding between the expansive agent and the concrete matrix, reduces corrosive ion penetration channels, and synergistically enhances the corrosion resistance of the expansive agent's fluorine element, further reducing the salt erosion strength loss rate, improving the corrosion resistance of the concrete, and extending the service life of the tunnel lining.

[0061] Referring to Table 1 and combining Examples 2 and 4, it can be seen that, compared to Example 2, Example 4 uses an expansion agent with added nano-silica. Without interfering with the core metathesis reaction and expansion crystal formation of the expansion agent, it effectively fills the micropores inside and at the interface of the expansion crystals, improving the structural density and uniformity of the expansion agent. Simultaneously, it enhances the interfacial bonding force between the expansion agent and the concrete matrix, improves the dispersibility of the expansion agent in concrete, and avoids localized performance unevenness caused by particle agglomeration. The synergistic effect of nano-silica and organic bentonite further optimizes the microporous structure of the concrete and reduces porosity. It blocks water seepage channels and effectively inhibits the formation of early plastic cracks and long-term drying shrinkage cracks in concrete, significantly improving the crack resistance, impermeability, and volume stability of concrete. In terms of mechanical properties, the synergistic effect of nano-silica and concrete hydration products further strengthens the strength of the concrete matrix. In terms of corrosion resistance, nano-silica fills the micropores of concrete, further blocking the intrusion of corrosive ions, and forms a synergistic effect with the fluorine element corrosion-resistant protective layer of the expansion agent, reducing the strength loss rate of concrete due to salt erosion. Compared with Example 2, the corrosion resistance is significantly optimized, and it is more resistant to the erosion of complex corrosive environments.

[0062] Referring to Table 1 and combining Examples 3, 4, and 5, it can be seen that, compared to Examples 3 and 4, Example 5 uses an expansion agent modified with a combination of KH-550 and nano-silica, achieving complementary advantages of the two modifiers: KH-550 effectively improves the dispersibility of the expansion agent, strengthens its interfacial adhesion with various concrete components, and ensures the uniformity of expansion compensation; nano-silica fills the expansion crystals and micropores of the concrete, improving the density of the expansion agent and the strength of the concrete matrix. The synergistic effect of the two further optimizes the microporous structure of the concrete, significantly enhancing its crack resistance and impermeability. This more effectively inhibits the formation of various cracks, blocks water seepage channels, and improves the volume stability and durability of concrete. In terms of mechanical properties, the synergistic effect of compound modification further enhances the early and long-term strength of concrete. In terms of corrosion resistance, the two modifiers work synergistically, strengthening interfacial adhesion and reducing corrosion channels through KH-550, and filling pores and blocking corrosion ions through nano-silica. At the same time, the fluorine element of the expansion agent has a synergistic effect on corrosion resistance, making the salt erosion strength loss rate of Example 5 significantly lower than that of Examples 3 and 4, and achieving a better level of corrosion resistance, fully demonstrating the synergistic effect of compound modification.

[0063] Referring to Table 1 and combining Examples 5 and 6, it can be seen that, compared to Example 5, Example 6 uses the composite modified organic bentonite specially prepared in this application, which has a more significant synergistic effect with the expansive agent. It can better exert the filling and blocking effect of the lamellar structure, further optimize the microporous structure of concrete, reduce porosity, block water seepage channels, and effectively reduce the generation of early plastic cracks in concrete, reduce long-term drying shrinkage deformation, and significantly improve the crack resistance and impermeability of concrete. In terms of mechanical properties, the composite modified organic bentonite prepared in this application can more strongly strengthen the interfacial bonding force between the components, forming a more stable overall structure with the expansive agent and concrete matrix, thus improving the early and long-term strength of concrete. In terms of corrosion resistance, the composite modified organic bentonite prepared in this application has better lamellar dispersion than commercially available organic bentonite, and its effect of blocking corrosion ions is more significant. In synergy with the expansive agent, it further reduces the salt erosion strength loss rate. Compared with Example 5, the corrosion resistance is further improved, making it more suitable for the corrosive environment of the Shaanxi-Gansu-Ningxia saline soil area.

[0064] Referring to Table 1 and combining Examples 6 and 7, it can be seen that, compared to Example 6, Example 7 uses ultrasonically activated composite modified organic bentonite. The ultrasonic action promotes the intercalation and dispersion of the modifier between bentonite layers, resulting in fully exfoliated organic bentonite sheets and a more porous structure. This allows for a closer interaction with the calcium aluminofluorosilicate crystals generated by the expanding agent. The synergistic effect of these two factors further optimizes the microporous structure of the concrete, more effectively blocking seepage channels and inhibiting the formation of various cracks, significantly improving the crack resistance and impermeability of the concrete. Regarding mechanical properties… The ultrasonically activated organic bentonite exhibits stronger interfacial bonding with various concrete components, which can synergistically enhance the strength of the concrete matrix and improve the early and long-term load-bearing capacity of the concrete. In terms of corrosion resistance, the ultrasonically activated organic bentonite exhibits more thorough lamellae peeling, resulting in more prominent effects in filling pores and blocking corrosion ions. In synergy with the expansion agent and modified components, it further reduces the strength loss rate due to salt erosion. Compared with Example 6, the corrosion resistance is significantly optimized, enabling it to better resist the long-term erosion of corrosion ions in saline soil areas and ensure the long-term stability of the tunnel lining structure.

[0065] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A type of tunnel lining concrete, characterized in that, The raw materials include the following parts by weight: 320-380 parts silicate cement, 60-100 parts fly ash, 40-80 parts slag powder, 950-1100 parts coarse aggregate, 750-850 parts fine aggregate, 30-55 parts expansion agent, 0.8-1.2 parts polypropylene short fiber, 4.5-6.5 parts polycarboxylate superplasticizer, and 150-170 parts water; The expanding agent is prepared by a metathesis reaction of calcium aluminosilicate clinker, sodium fluoroaluminate, and water.

2. The tunnel lining concrete according to claim 1, characterized in that, The preparation method of the expansion agent is as follows: 70-80 parts by weight of calcium aluminosilicate clinker and 20-30 parts by weight of sodium fluoroaluminate are added to 5-8 parts by weight of deionized water and reacted at room temperature for 2-3 hours to obtain the expansion agent.

3. The tunnel lining concrete according to claim 1, characterized in that, The preparation method of the expansion agent is as follows: 70-80 parts by weight of calcium aluminosilicate clinker, 20-30 parts by weight of sodium fluoroaluminate and 0.5-1 parts by weight of γ-aminopropyltriethoxysilane are added to 5-8 parts by weight of deionized water and reacted at room temperature for 2-3 hours to obtain the expansion agent.

4. The tunnel lining concrete according to claim 1, characterized in that, The preparation method of the expansion agent is as follows: 70-80 parts by weight of calcium aluminosilicate clinker, 20-30 parts by weight of sodium fluoroaluminate and 0.3-0.8 parts by weight of nano silica are added to 5-8 parts by weight of deionized water and reacted at room temperature for 2-3 hours to obtain the expansion agent.

5. The tunnel lining concrete according to claim 1, characterized in that, The preparation method of the expansion agent is as follows: 70-80 parts by weight of calcium aluminosilicate clinker, 20-30 parts by weight of sodium fluoroaluminate, 0.3-0.8 parts by weight of nano-silica and 0.5-1 parts by weight of γ-aminopropyltriethoxysilane are added to 5-8 parts by weight of deionized water and reacted at room temperature for 2-3 hours to obtain the expansion agent.

6. The tunnel lining concrete according to claim 1, characterized in that, The raw materials also include 8-15 parts by weight of organic bentonite.

7. The tunnel lining concrete according to claim 6, characterized in that, The organic bentonite is obtained by modifying sodium-based bentonite with γ-polyglutamic acid and hexadecyltrimethylammonium bromide.

8. The tunnel lining concrete according to claim 7, characterized in that, The mass ratio of γ-polyglutamic acid to hexadecyltrimethylammonium bromide is 1:(3-5).

9. The tunnel lining concrete according to claim 6, characterized in that, The organic bentonite is obtained by modifying sodium-based bentonite with γ-polyglutamic acid and hexadecyltrimethylammonium bromide, followed by ultrasonic activation. The mass ratio of γ-polyglutamic acid to hexadecyltrimethylammonium bromide is 1:(3-5). The ultrasonic activation treatment is performed at a power of 120-200W, a temperature of 40-60℃, and a time of 30-60min.

10. A method for preparing tunnel lining concrete according to any one of claims 1-9, characterized in that, Includes the following steps: According to the formula, silicate cement, fly ash, slag powder, coarse aggregate, fine aggregate, and polypropylene short fiber are mixed evenly, and then the remaining raw materials are added and stirred to obtain tunnel lining concrete.

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