Micro-swelling anti-cracking waterproof composite deep groove filling material and preparation method thereof

Abstract

The application belongs to the technical field of building materials, and particularly relates to a micro-peng anti-cracking waterproof composite deep groove filling material and a preparation method thereof. The micro-peng anti-cracking waterproof composite deep groove filling material provided by the application comprises cement, gypsum, mineral powder, nano silicon oxide, coarse aggregate, fine aggregate, modified fiber, expansion agent, polycarboxylic acid water reducing agent and water. The application adopts polyacrylamide, calcium sulphoaluminate and magnesium oxide to jointly form the expansion agent, and jointly form the early-late full-cycle shrinkage compensation in the hydration process of the concrete, effectively improves the compactness of the concrete, and further improves the waterproof performance of the concrete. Sodium dodecyl benzene sulfonate and propylene glycol block polyether are used to compound and modify the graphene oxide, and the graphene oxide is connected to the surface of the basalt fiber through gamma-aminopropyl triethoxysilane, so that the bonding strength of the basalt fiber and the cement matrix and the compactness of the cement matrix are improved, and the waterproof and anti-cracking performance of the concrete is further improved.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a micro-expansion crack-resistant and waterproof composite deep trench filler and its preparation method. Background Technology

[0002] In the field of building construction, the filling construction of deep trenches (such as underground utility tunnel trenches, building trenches, and foundation pit side trenches) is a crucial step in ensuring structural stability and durability, and its filling quality directly affects the overall safety and service life of the building. As infrastructure construction expands into deeper and more confined spaces, the technical challenges of deep trench filling are becoming increasingly prominent.

[0003] Traditional filling materials often use plain soil, lime-soil, or graded sand and gravel, requiring layered compaction and involving cumbersome construction processes. Mechanical work is difficult to implement in confined spaces, and manual operation can easily lead to insufficient compaction, resulting in uneven settlement later on, which can tear the waterproofing layer and cause leakage. At the same time, frequent extreme weather events cause increased fluctuations in environmental humidity. Traditional materials, with their insufficient crack resistance, are prone to macroscopic cracks, further exacerbating water seepage problems, severely affecting structural durability and increasing maintenance costs.

[0004] While existing improved filler materials attempt to enhance performance by adding fibers or modifiers, significant limitations remain: single materials struggle to simultaneously achieve both crack resistance and waterproofing; organic modifiers exhibit poor compatibility with inorganic matrix materials, resulting in insufficient long-term performance; fiber materials possess sufficient toughness but insufficient hardness, and modification treatments significantly increase costs; furthermore, some materials exhibit poor flowability, failing to meet the self-sealing construction requirements of deep trenches in confined spaces. Currently, the requirements for deep trench fillers in underground engineering, transportation, and water conservancy fields have evolved from simple compaction to a comprehensive approach encompassing micro-expansion compensation for shrinkage, high-efficiency crack resistance, long-term waterproofing, convenient construction, and environmental protection and energy conservation. Therefore, developing a composite filler that can adapt to the complex construction environment of deep trenches and achieve synergistic crack resistance and waterproofing has become a key direction for addressing existing technological pain points and promoting improvements in engineering quality.

[0005] Chinese patent application CN119750963A discloses a self-healing material for waterproofing, crack resistance, and moisture protection of concrete structures, comprising cement, sand, gravel, reinforcing materials, polymer-modified asphalt, water-reducing agent, admixtures, chemical self-healing agent, foaming agent, and water. The admixtures are one or more of concrete expansion agents, fast hardeners, plasticizers, polyurethane-type flexible agents, and concrete retarders. The reinforcing materials are one or more of microfibers, slag, fly ash, silane ash, and cellulose materials. The cellulose materials are one or more of wood, hemp, polypropylene fibers, and polyester fibers. This material enhances the crack resistance of concrete structures through its formulation design and improves its waterproof performance by adding asphalt and foaming agents. However, the combined use of expanding agents and foaming agents in its formulation can easily lead to excessively high porosity and uneven pore distribution within the concrete, resulting in reduced crack resistance and thus affecting the waterproofing effect. In addition, the amount of polymer-modified asphalt used is only 5%-10%, and the mixing process with cementitious materials and aggregates is simple, making it easy for it to precipitate during hydration, failing to form a continuous waterproof membrane and causing the waterproof barrier to break. Summary of the Invention

[0006] In order to solve the technical problems such as poor crack resistance and waterproofing effect in the above-mentioned related technologies, the purpose of this invention is to provide a micro-expanded crack-resistant and waterproof composite deep trench filler and its preparation method.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A micro-expansion, crack-resistant, and waterproof composite deep trench filler comprises the following components in parts by weight:

[0009] 500-600 parts cement, 50-60 parts gypsum, 100-120 parts mineral powder, 30-50 parts nano-silica, 800-1000 parts coarse aggregate, 1100-1300 parts fine aggregate, 60-80 parts modified fiber, 40-50 parts expansion agent, 15-20 parts polycarboxylate superplasticizer, and 450-600 parts water;

[0010] The expanding agent includes polyacrylamide, calcium sulfoaluminate, and magnesium oxide.

[0011] In the above scheme, the polyacrylamide molecular chains in the expanding agent form an interwoven network structure inside the concrete. When cracks appear in the concrete due to shrinkage, the network structure can absorb energy through molecular chain stretching, inhibiting the propagation of crack tips. The polyacrylamide molecules absorb and expand, forming a gel-like structure that further seals the microchannels and improves the concrete's impermeability. Calcium sulfoaluminate reacts with gypsum and calcium hydroxide in the early stages of cement hydration to produce a large number of needle-like ettringite crystals, generating rapid and concentrated expansion pressure. This can compensate for the plastic shrinkage and short-term drying shrinkage of the concrete, preventing microcracks caused by water evaporation or volume shrinkage in the early stages of hydration. Simultaneously, the water-retention properties of polyacrylamide can delay water evaporation, providing a stable hydration environment for the expansion of ettringite crystals and promoting secondary cement hydration, thus self-repairing microcracks. Magnesium oxide undergoes a slow hydration reaction, and its hydration process can compensate for the later temperature shrinkage and long-term drying shrinkage of the concrete, forming a full-cycle shrinkage compensation from early to late stages together with calcium sulfoaluminate. Nano-silica can fill the micropore structure and improve interfacial adhesion.

[0012] Furthermore, the preparation method of the expansion agent is as follows: calcium sulfoaluminate and magnesium oxide are added to deionized water, ultrasonically dispersed, hexadecyltrimethoxysilane is added, stirred for 3-4 hours, allowed to stand and separate into layers, filtered, washed, dried, polyacrylamide is added, and mixed evenly to obtain the expansion agent.

[0013] In the above scheme, the modification of calcium sulfoaluminate and magnesium oxide with hexadecyltrimethoxysilane can not only improve the interfacial compatibility between calcium sulfoaluminate and magnesium oxide and cement paste, reduce the bonding defects between the expansion agent and the matrix, and make the expansion force evenly transmitted to the interior of the concrete, avoiding local expansion and stress concentration that could lead to concrete cracking, but also the long carbon chain and siloxane bond of the silane coupling agent can form a strong hydrophobic network protective layer inside the capillary pores of the concrete, making it difficult for water to enter the interior of the concrete through capillary action, thus significantly improving the waterproofness and impermeability of the concrete.

[0014] Furthermore, in the preparation method of the expanding agent, the mass ratio of calcium sulfoaluminate, magnesium oxide and polyacrylamide is (11-15):(6-11):(3-7).

[0015] In the above scheme, the compensation shrinkage mechanism of concrete is controlled by adjusting the mass ratio of calcium sulfoaluminate, magnesium oxide and polyacrylamide. If calcium sulfoaluminate is excessive, the excessive formation of ettringite in the early stage will lead to stress relaxation of concrete and increase internal porosity. If magnesium oxide is excessive, the large expansion of concrete in the later stage will destroy the stable structure of the hardened concrete and produce internal microcracks. If polyacrylamide is excessive, it will increase the viscosity of concrete, making it easy to trap air bubbles during mixing, forming stress concentration points and reducing crack resistance.

[0016] Furthermore, in the preparation method of the expanding agent, the amount of hexadecyltrimethoxysilane used is 2%-5% of the sum of the mass of calcium sulfoaluminate and magnesium oxide.

[0017] Further, the preparation method of the modified fiber is as follows: Graphene oxide is dispersed in deionized water to obtain a dispersion; sodium dodecylbenzenesulfonate and propylene glycol block polyether are added to deionized water and stirred at 60-70℃ to dissolve. The dispersion is added while stirring, and after stirring for 1-2 hours, it is ultrasonically treated for 20-40 minutes, centrifuged, washed, and dried to obtain modified graphene oxide; basalt fibers are soaked in anhydrous ethanol and dried, then immersed in sodium hydroxide solution and kept at 60-65℃ for 2-2.5 hours. After washing with deionized water, they are soaked in hydrochloric acid solution for 20-30 minutes until the washing solution is neutral, and then dried to obtain active basalt fibers; the modified graphene oxide is dispersed in deionized water, γ-aminopropyltriethoxysilane is added, stirred evenly, and then active basalt fibers are added. Stirring is continued for 4-6 hours, the fibers are removed, washed with deionized water, and dried to obtain modified fibers.

[0018] In the above scheme, sodium dodecylbenzenesulfonate and propylene glycol block polyether are used to modify graphene oxide. The dispersibility of graphene oxide is improved through electrostatic interaction and steric hindrance. This uniform dispersion can ensure that the modified graphene oxide is distributed to every microcrack and fills the capillary pores of cement hydration products, thereby reducing the porosity of concrete. At the same time, the sulfonic acid groups, hydroxyl groups and other oxygen-containing functional groups on the surface of graphene oxide can serve as crystal nuclei for cement hydration, accelerate the formation of calcium silicate gel, increase the density of hydration products, and improve the waterproof performance of concrete.

[0019] Sodium hydroxide was used to etch the inert layer on the surface of basalt fibers, exposing more silicate hydroxyl groups. Neutralization of sodium hydroxide with hydrochloric acid further increased the number of surface active sites, providing more active sites for the subsequent introduction of silane coupling agents and modified graphene oxide. One end of γ-aminopropyltriethoxysilane reacts with the hydroxyl groups on the basalt fiber surface to form a covalent bond, while the other end forms hydrogen bonds or electrostatic interactions with sulfonic acid groups and carboxyl groups on the modified graphene oxide surface. This loading of modified graphene oxide onto the basalt fiber surface eliminates interfacial gaps between the basalt fiber and the cement matrix, improving the crack resistance of concrete.

[0020] Furthermore, in the method for preparing the modified fiber, the mass ratio of graphene oxide to sodium dodecylbenzenesulfonate and propylene glycol block polyether is 1:(4-5):(2-3).

[0021] Furthermore, in the method for preparing the modified fiber, the sodium hydroxide solution has a mass percentage of 5%-10%, and the hydrochloric acid solution has a concentration of 0.3-0.5 mol / L.

[0022] Furthermore, in the preparation method of the modified fiber, the mass ratio of modified graphene oxide to γ-aminopropyltriethoxysilane and active basalt fiber is (10-15):(7-10):(25-30).

[0023] In the above scheme, the loading of graphene oxide on the surface of basalt fiber is adjusted by adjusting the mass ratio of modified graphene oxide, γ-aminopropyltriethoxysilane and active basalt fiber. If the loading of graphene oxide is too high, agglomerates will form on the surface of basalt fiber, which will not only fail to improve the crack resistance of concrete, but will also become stress concentration points and induce new cracks.

[0024] Furthermore, the coarse aggregate is 10-25mm continuously graded crushed stone with an apparent density of 2900 kg / m³. 3 The fine aggregate is coarse sand with a fineness modulus of 3.3-3.7.

[0025] The present invention also provides a method for preparing the micro-expansion crack-resistant and waterproof composite deep trench filler, specifically: mixing and stirring cement, gypsum, mineral powder, nano-silica and an expansion agent to obtain mixture I; mixing and stirring water and polycarboxylate superplasticizer to obtain mixture II; adding mixture II to mixture I, stirring evenly, then adding coarse aggregate, fine aggregate and modified fiber, and stirring to obtain the micro-expansion crack-resistant and waterproof composite deep trench filler.

[0026] In the above scheme, the solid powder and liquid components are mixed evenly in stages to avoid the water-reducing agent and solid powder from clumping together directly, and to prevent the modified fiber from being wrapped by dry powder and difficult to disperse. The expansion agent and modified fiber work together to form a dual protection of shrinkage compensation and crack blocking, which effectively improves the waterproof and crack-resistant performance of concrete.

[0027] Compared with existing technologies, the micro-expansion crack-resistant and waterproof composite deep trench filler and its preparation method provided by the present invention have the following technical advantages:

[0028] (1) The present invention provides that by adding nano-silica, modified fiber, expansion agent and other components to the formula and adjusting the amount of each component in the formula, the waterproof and crack-resistant performance of the composite deep trench filler is effectively improved.

[0029] (2) The present invention uses polyacrylamide, calcium sulfoaluminate and magnesium oxide to form an expansion agent, and adjusts the dosage of each component to form early-late full-cycle shrinkage compensation during the concrete hydration process, effectively improving the density of concrete and thus improving the waterproof performance of concrete.

[0030] (3) In this invention, sodium dodecylbenzenesulfonate and propylene glycol block polyether are used to modify graphene oxide. γ-aminopropyltriethoxysilane is attached to the surface of basalt fiber, which improves the bonding strength between basalt fiber and cement matrix and the density of cement matrix, thereby improving the waterproof and crack-resistant performance of concrete. Attached Figure Description

[0031] Figure 1 , Figure 2 This is a scanning electron microscope image of the modified fiber obtained in Example 3. Detailed Implementation

[0032] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments. Those skilled in the art can make various modifications based on the fundamental principles of the present invention, but all modifications that do not depart from the fundamental principles of the present invention are within its scope.

[0033] Unless otherwise specified, all raw materials mentioned in this specific embodiment are commercially available. The cement mentioned in this specific embodiment is P·O 52.5 silicate cement; the propylene glycol block polyether mentioned in the preparation method of the modified fiber is propylene glycol block polyether L-64.

[0034] The preparation method of the micro-expansion crack-resistant and waterproof composite deep trench filler described in this specific embodiment is as follows: cement, gypsum, mineral powder, nano-silica and expansion agent are mixed and stirred evenly to obtain mixture I; water and polycarboxylate superplasticizer are mixed and stirred evenly to obtain mixture II; mixture II is added to mixture I, stirred evenly, and then coarse aggregate, fine aggregate and modified fiber are added and stirred to obtain the micro-expansion crack-resistant and waterproof composite deep trench filler.

[0035] Preparation Example 1

[0036] The modified fiber was prepared as follows: 60g of graphene oxide was dispersed in deionized water to obtain a dispersion with a mass concentration of 1mg / mL; 240g of sodium dodecylbenzenesulfonate and 120g of propylene glycol block polyether were added to 500mL of deionized water and stirred at 60℃ to dissolve. The dispersion was slowly added while stirring at 400rpm. After stirring for 1h, the mixture was ultrasonically treated at a frequency of 20kHz for 20min, centrifuged, washed three times with deionized water, and dried to obtain modified graphene oxide.

[0037] Basalt fibers were soaked in anhydrous ethanol for 20 minutes and then dried. They were then immersed in a 5% sodium hydroxide solution and kept at 60°C for 2.5 hours. After filtration, they were washed three times with deionized water and then soaked in a 0.3 mol / L hydrochloric acid solution for 20 minutes. After filtration, they were washed with deionized water until the washing solution was neutral and then dried to obtain active basalt fibers.

[0038] 30g of modified graphene oxide was dispersed in 500mL of deionized water, 21g of γ-aminopropyltriethoxysilane was added, and after stirring evenly, 75g of active basalt fiber was added. Stirring was continued for 4 hours. The fiber was then removed, washed with deionized water, and dried to obtain the modified fiber.

[0039] Preparation Example 2

[0040] The modified fiber was prepared as follows: 60g of graphene oxide was dispersed in deionized water to obtain a dispersion with a mass concentration of 1mg / mL; 300g of sodium dodecylbenzenesulfonate and 180g of propylene glycol block polyether were added to 500mL of deionized water and stirred at 70℃ to dissolve. The dispersion was slowly added while stirring at 400rpm. After stirring for 2h, the mixture was ultrasonically treated at a frequency of 30kHz for 40min, centrifuged, washed three times with deionized water, and dried to obtain modified graphene oxide.

[0041] Basalt fibers were soaked in anhydrous ethanol for 20 minutes and then dried. They were then immersed in a 10% sodium hydroxide solution and kept at 65°C for 2 hours. After filtration, they were washed three times with deionized water and then soaked in a 0.5 mol / L hydrochloric acid solution for 30 minutes. After filtration, they were washed with deionized water until the washing solution was neutral and then dried to obtain active basalt fibers.

[0042] 45g of modified graphene oxide was dispersed in 500mL of deionized water, 30g of γ-aminopropyltriethoxysilane was added, and after stirring evenly, 90g of active basalt fiber was added. Stirring was continued for 6 hours. The fiber was then removed, washed with deionized water, and dried to obtain the modified fiber.

[0043] Preparation Example 3

[0044] The modified fiber was prepared as follows: 60g of graphene oxide was dispersed in deionized water to obtain a dispersion with a mass concentration of 1mg / mL; 265g of sodium dodecylbenzenesulfonate and 150g of propylene glycol block polyether were added to 500mL of deionized water and stirred at 65℃ to dissolve. The dispersion was slowly added while stirring at 400rpm. After stirring for 1.5h, the mixture was ultrasonically treated at a frequency of 25kHz for 30min, centrifuged, washed three times with deionized water, and dried to obtain modified graphene oxide.

[0045] Basalt fibers were soaked in anhydrous ethanol for 20 minutes and then dried. They were then immersed in an 8% sodium hydroxide solution and kept at 63°C for 2.2 hours. After filtration, they were washed three times with deionized water and then soaked in a 0.4 mol / L hydrochloric acid solution for 25 minutes. After filtration, they were washed with deionized water until the washing solution was neutral and then dried to obtain active basalt fibers.

[0046] 40g of modified graphene oxide was dispersed in 500mL of deionized water, 26g of γ-aminopropyltriethoxysilane was added, and after stirring evenly, 82g of active basalt fiber was added. Stirring was continued for 5h, the fiber was removed, washed with deionized water, and dried to obtain modified fiber.

[0047] Preparation Example 4

[0048] The modified fiber was prepared as follows: 60g of graphene oxide was dispersed in deionized water to obtain a dispersion with a mass concentration of 1mg / mL; 272g of sodium dodecylbenzenesulfonate and 145g of propylene glycol block polyether were added to 500mL of deionized water and stirred at 65℃ to dissolve. The dispersion was slowly added while stirring at 400rpm. After stirring for 1.5h, the mixture was ultrasonically treated at a frequency of 25kHz for 30min, centrifuged, washed three times with deionized water, and dried to obtain modified graphene oxide.

[0049] Basalt fibers were soaked in anhydrous ethanol for 20 minutes and then dried. They were then immersed in an 8% sodium hydroxide solution and kept at 63°C for 2.2 hours. After filtration, they were washed three times with deionized water and then soaked in a 0.4 mol / L hydrochloric acid solution for 25 minutes. After filtration, they were washed with deionized water until the washing solution was neutral and then dried to obtain active basalt fibers.

[0050] 42g of modified graphene oxide was dispersed in 500mL of deionized water, 27g of γ-aminopropyltriethoxysilane was added, and after stirring evenly, 84g of active basalt fiber was added. Stirring was continued for 5h, the fiber was removed, washed with deionized water, and dried to obtain modified fiber.

[0051] Example 1

[0052] A micro-expansion, crack-resistant, and waterproof composite deep trench filler comprises the following components in parts by weight:

[0053] 500g cement, 50g gypsum, 100g mineral powder, 30g nano-silica, 1000g coarse aggregate, 1300g fine aggregate, 60g modified fiber, 40g expansion agent, 15g polycarboxylate superplasticizer, and 450g water; the modified fiber was prepared by Preparation Example 1.

[0054] The preparation method of the swelling agent is as follows: 22g of calcium sulfoaluminate and 12g of magnesium oxide are added to deionized water, ultrasonically dispersed at 30kHz for 30min, 0.68g of hexadecyltrimethoxysilane is added, stirred for 3h, allowed to stand and separate into layers, filtered, washed with deionized water, dried at 60℃, 6g of polyacrylamide is added, and mixed evenly to obtain the swelling agent.

[0055] The coarse aggregate is 10mm continuously graded crushed stone with an apparent density of 2900 kg / m³. 3Fine aggregate is coarse sand with a fineness modulus of 3.3.

[0056] Example 2

[0057] A micro-expansion, crack-resistant, and waterproof composite deep trench filler comprises the following components in parts by weight:

[0058] 600g cement, 60g gypsum, 120g mineral powder, 50g nano-silica, 800g coarse aggregate, 1100g fine aggregate, 80g modified fiber, 50g expansion agent, 20g polycarboxylate superplasticizer, and 600g water; the modified fiber was prepared by Preparation Example 2.

[0059] The preparation method of the swelling agent is as follows: 30g of calcium sulfoaluminate and 22g of magnesium oxide are added to deionized water, ultrasonically dispersed at 40kHz for 20min, 2.6g of hexadecyltrimethoxysilane is added, stirred for 4h, allowed to stand and separate into layers, filtered, washed with deionized water, dried at 70℃, 14g of polyacrylamide is added, and mixed evenly to obtain the swelling agent.

[0060] The coarse aggregate is 25mm continuously graded crushed stone with an apparent density of 2900 kg / m³. 3 Fine aggregate is coarse sand with a fineness modulus of 3.7.

[0061] Example 3

[0062] A micro-expansion, crack-resistant, and waterproof composite deep trench filler comprises the following components in parts by weight:

[0063] 550g cement, 55g gypsum, 110g mineral powder, 40g nano-silica, 900g coarse aggregate, 1200g fine aggregate, 70g modified fiber, 45g expansion agent, 17g polycarboxylate superplasticizer, and 480g water; the modified fiber was prepared by Preparation Example 3.

[0064] The preparation method of the swelling agent is as follows: 28g of calcium sulfoaluminate and 16g of magnesium oxide are added to deionized water, ultrasonically dispersed at 35kHz for 25min, 1.32g of hexadecyltrimethoxysilane is added, stirred for 3.5h, allowed to stand and separate into layers, filtered, washed with deionized water, dried at 65℃, 10g of polyacrylamide is added, and mixed evenly to obtain the swelling agent.

[0065] The coarse aggregate is 15mm continuously graded crushed stone with an apparent density of 2900 kg / m³. 3 Fine aggregate is coarse sand with a fineness modulus of 3.5.

[0066] Example 4

[0067] A micro-expansion, crack-resistant, and waterproof composite deep trench filler comprises the following components in parts by weight:

[0068] 550g cement, 58g gypsum, 110g mineral powder, 40g nano-silica, 900g coarse aggregate, 1200g fine aggregate, 70g modified fiber, 45g expansion agent, 17g polycarboxylate superplasticizer, and 480g water; the modified fiber was prepared by Preparation Example 4.

[0069] The preparation method of the swelling agent is as follows: 26g of calcium sulfoaluminate and 19g of magnesium oxide are added to deionized water, ultrasonically dispersed at 35kHz for 25min, 1.8g of hexadecyltrimethoxysilane is added, stirred for 3.5h, allowed to stand and separate into layers, filtered, washed with deionized water, dried at 65℃, 11g of polyacrylamide is added, and mixed evenly to obtain the swelling agent.

[0070] The coarse aggregate is 20mm continuously graded crushed stone with an apparent density of 2900 kg / m³. 3 Fine aggregate is coarse sand with a fineness modulus of 3.5.

[0071] Comparative Example 1

[0072] The composite deep trench filler in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that the expanding agent in this comparative example is calcium sulfoaluminate.

[0073] Comparative Example 2

[0074] The composite deep trench filler in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that the expanding agent in this comparative example is magnesium oxide.

[0075] Comparative Example 3

[0076] The composite deep trench filler in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that in the preparation method of the expanding agent in this comparative example, an equal amount of deionized water is used instead of hexadecyltrimethoxysilane.

[0077] Comparative Example 4

[0078] The composite deep trench filler in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that an equal amount of basalt fiber is used instead of modified fiber in this comparative example.

[0079] Comparative Example 5

[0080] The composite deep trench filler in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that an equal amount of graphene oxide is used instead of modified graphene oxide in the preparation method of the modified fiber in this comparative example.

[0081] Comparative Example 6

[0082] The composite deep trench filler in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that in the preparation method of the modified fiber in this comparative example, an equal amount of deionized water is used instead of sodium hydroxide solution and hydrochloric acid solution.

[0083] Test case

[0084] According to national standards GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", GB / T50081-2019 "Test Methods of Physical and Mechanical Properties of Concrete", GB / T50082-2024 "Standard for Test Methods of Long-Term Performance and Durability of Concrete", JC474-2008 "Mortar and Concrete Waterproofing Agents", and GB / T23439-2017 "Concrete Expansion Agents", the composite deep trench fillers prepared in Examples 1-4 and Comparative Examples 1-6 were tested for their expansion, crack resistance, and waterproofing properties. The impermeability was calculated based on the penetration height. The test results are shown in Table 1.

[0085] Table 1 Performance Test Results

[0086]

[0087] As shown in Table 1, the micro-expansion crack-resistant and waterproof composite deep trench filler provided by this invention has high mechanical properties, impermeability and waterproof performance, and crack resistance. During cement hydration, it can slightly expand to compensate for the shrinkage during concrete hydration. Combining the experimental results of Examples 1-4 and Comparative Examples 1-3, it can be seen that using polyacrylamide, calcium sulfoaluminate, and magnesium oxide as the expansive agent can form a full-cycle shrinkage compensation mechanism during cement hydration, enabling self-repair of micro-cracks generated during cement hydration and improving the density of concrete. Modifying calcium sulfoaluminate and magnesium oxide with hexadecyltrimethoxysilane can improve the bond strength between the expansive agent and the cement matrix, reduce the degree of concrete cracking, and enhance impermeability and waterproof performance. Based on the experimental results of Examples 1-4 and Comparative Examples 4-6, it can be seen that the modified basalt fiber can effectively improve the crack resistance of concrete. The compound modification of graphene oxide with sodium dodecylbenzenesulfonate and propylene glycol block polyether can fill the capillary pores of cement hydration products and promote cement hydration. The activation of basalt fiber with acid and alkali solutions can improve the adhesion rate of graphene oxide on the surface of basalt fiber, thereby improving the crack resistance and waterproof performance of concrete.

[0088] Furthermore, the modified fibers obtained in Example 3 were subjected to scanning electron microscopy tests, and the results are shown in [Figure number missing]. Figure 1 and Figure 2 .Depend on Figure 1 and Figure 2It is known that the modified fiber prepared by the present invention has graphene oxide particles uniformly attached to its surface, which improves the bonding strength between basalt fiber and cement aggregate, thereby improving the crack resistance of concrete.

[0089] The above embodiments are merely illustrative of the present invention and are not intended to limit the invention. Those skilled in the art should not modify the above embodiments without departing from the spirit and scope of the present invention. All equivalent modifications or alterations made by those skilled in the art without departing from the technical concept of the present invention are still within the protection scope of the present invention.

Claims

1. A micro-expanding, crack-resistant, and waterproof composite deep trench filler, characterized in that, The components include the following parts by weight: 500-600 parts cement, 50-60 parts gypsum, 100-120 parts mineral powder, 30-50 parts nano-silica, 800-1000 parts coarse aggregate, 1100-1300 parts fine aggregate, 60-80 parts modified fiber, 40-50 parts expansion agent, 15-20 parts polycarboxylate superplasticizer, and 450-600 parts water; The preparation method of the expansion agent is as follows: calcium sulfoaluminate and magnesium oxide are added to deionized water, ultrasonically dispersed, hexadecyltrimethoxysilane is added, stirred for 3-4 hours, allowed to stand and separate into layers, filtered, washed, dried, polyacrylamide is added, and mixed evenly to obtain the product. The modified fiber is prepared by dispersing graphene oxide in deionized water to obtain a dispersion; adding sodium dodecylbenzenesulfonate and propylene glycol block polyether to deionized water, stirring and dissolving at 60-70℃, adding the dispersion while stirring, stirring for 1-2 hours, ultrasonically treating for 20-40 minutes, centrifuging, washing, and drying to obtain modified graphene oxide. Basalt fibers were soaked in anhydrous ethanol and dried. They were then immersed in sodium hydroxide solution and kept at 60-65℃ for 2-2.5 hours. After washing with deionized water, they were soaked in hydrochloric acid solution for 20-30 minutes until the washing solution was neutral. After drying, active basalt fibers were obtained. Modified graphene oxide was dispersed in deionized water, and γ-aminopropyltriethoxysilane was added. After stirring evenly, active basalt fibers were added and stirring was continued for 4-6 hours. The fibers were then removed, washed with deionized water, and dried to obtain modified fibers.

2. The micro-expanding, crack-resistant, and waterproof composite deep trench filler according to claim 1, characterized in that, In the preparation method of the expanding agent, the mass ratio of calcium sulfoaluminate, magnesium oxide and polyacrylamide is (11-15):(6-11):(3-7).

3. The micro-expanding, crack-resistant, and waterproof composite deep trench filler according to claim 1, characterized in that, In the preparation method of the expanding agent, the amount of hexadecyltrimethoxysilane used is 2%-5% of the sum of the mass of calcium sulfoaluminate and magnesium oxide.

4. The micro-expanding, crack-resistant, and waterproof composite deep trench filler according to claim 1, characterized in that, In the preparation method of the modified fiber, the mass ratio of graphene oxide to sodium dodecylbenzenesulfonate and propylene glycol block polyether is 1:(4-5):(2-3).

5. The micro-expanding, crack-resistant, and waterproof composite deep trench filler according to claim 1, characterized in that, In the preparation method of modified fibers, the mass percentage of sodium hydroxide solution is 5%-10%, and the concentration of hydrochloric acid solution is 0.3-0.5 mol / L.

6. The micro-expanding, crack-resistant, and waterproof composite deep trench filler according to claim 1, characterized in that, In the preparation method of modified fiber, the mass ratio of modified graphene oxide to γ-aminopropyltriethoxysilane and active basalt fiber is (10-15):(7-10):(25-30).

7. The micro-expanding, crack-resistant, and waterproof composite deep trench filler according to claim 1, characterized in that, The coarse aggregate is 10-25mm continuously graded crushed stone with an apparent density of 2900 kg / m³. 3 The fine aggregate is coarse sand with a fineness modulus of 3.3-3.

7.

8. The method for preparing the micro-expanding crack-resistant and waterproof composite deep trench filler according to any one of claims 1-7, characterized in that, Specifically, cement, gypsum, mineral powder, nano-silica and expansion agent are mixed and stirred evenly to obtain mixture I; water and polycarboxylate superplasticizer are mixed and stirred evenly to obtain mixture II; mixture II is added to mixture I, stirred evenly, and then coarse aggregate, fine aggregate and modified fiber are added and stirred to obtain micro-expansion crack-resistant waterproof composite deep trench filler.

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