Nanometer modified anti-rebound full-hole slag shotcrete

Abstract

The application relates to the technical field of hydraulic concrete materials, and specifically discloses a nano-modified anti-rebound full-tunnel-slag shotcrete, which is prepared from the following raw materials in parts by weight: tunnel-slag aggregate 665 parts, tunnel-slag sand 950 parts, ordinary Portland cement 396-436.5 parts, water 225 parts, polycarboxylate-based water reducing agent 10 parts and quickening agent 8.5 parts; the tunnel-slag aggregate is further subjected to nano-admixture modification treatment, and the nano-admixture is composed of nano-kaolin, nano-silicon dioxide and precision PCE solution. The anti-rebound shotcrete is prepared by modifying the tunnel-slag aggregate with the nano-admixture, full-quantization resource utilization of tunnel excavation slag is realized, the problems of land occupation and potential ecological pollution caused by the stacking of the slag are effectively alleviated, the cement consumption in the concrete is reduced, the construction cost is lowered, the rebound rate of the shotcrete can be obviously reduced, the compactness of the concrete is improved, and the compressive strength and crack resistance of the concrete are enhanced.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic concrete materials technology, specifically a nano-modified anti-rebound full-cavity slag sprayed concrete. Background Technology

[0002] In the excavation of hydraulic tunnels, the drill-and-blast method is widely used as the main construction technique. The blasting action results in a large amount of irregularly shaped rock debris with well-developed internal fissures. Traditionally, this debris needs to be transported to landfill sites for disposal, which not only increases transportation and treatment costs but also imposes an environmental burden. If this debris can be utilized as aggregate in shotcrete, turning waste into treasure, it can save on project investment, create considerable economic benefits, and be environmentally friendly.

[0003] Shotcrete is a core material for the initial support of tunnels, and its construction quality has a significant impact on the performance of the engineering structure. However, traditional shotcrete generally suffers from excessively high rebound rates (typically reaching 20%-25%, or even higher). Rebound not only causes huge material waste and increases project costs, but also deteriorates the construction environment, threatens the health of workers, and affects the uniformity and overall load-bearing capacity of the shotcrete layer. To address this, functional materials (minerals, metal oxides, organic compounds, etc.) are often added to shotcrete as admixtures to improve concrete performance and reduce the rebound rate. For example, patent CN115478880B proposes a construction method to reduce the rebound rate of shotcrete, with a binder-to-aggregate ratio of 1:3.5-5, aggregate sand content of 45%-60%, and water-to-binder ratio of 0.4-0.5. This method enhances the adhesion between slurries by adding a binder mainly composed of silica, calcium hydroxide, calcium oxide, magnesium hydroxide, carbon nanotubes, and cellulose to the original shotcrete raw materials, thereby reducing the rebound rate. For example, patent CN114538820B discloses a method for suppressing rebound of shotcrete based on full-process control, with material parameters as follows: cementitious material dosage 480~530kg / m³. 3 The water-cement ratio is 0.35–0.40, and the sand ratio is ≥60%. A key rebound-inhibiting material composed of hydroxypropyl methylcellulose, triethanolamine, sodium sulfate, polycarboxylate superplasticizer powder, and water is added to the concrete mix to adjust the fluidity and early strength of the shotcrete, so as to meet the requirements of low rebound shotcreting.

[0004] However, current research and applications are mainly based on conventional aggregates with good morphology and excellent gradation. Their technical approach focuses on optimizing the cementitious material system, without fully considering the fundamental challenges posed by the unique properties of the aggregates themselves. The content of needle-shaped and flaky particles (approximately 22%) and stone powder (approximately 30%) in tunnel slag aggregate significantly exceeds the requirements for aggregates in the "Technical Specification for Application of Shotcrete" (JGJ / T 372-2016) (needle-shaped and flaky particle content ≤12%, stone powder content ≤10%). This easily leads to insufficient paste bonding and weakened mechanical interlocking between aggregates in fresh concrete, jointly disrupting the "adhesion-cohesion-flexibility" performance balance required for shotcrete, thus causing severe rebound and paste loss problems. Therefore, there is an urgent need to develop a novel nano-admixture specifically designed for the characteristics of tunnel slag aggregate to effectively solve the problems of high rebound rate and deteriorated mechanical properties caused by high needle-shaped and flaky particle content and high stone powder content, thereby promoting the large-scale, efficient, and resource-based utilization of tunnel slag in shotcrete.

[0005] To address this, this invention develops a novel nano-admixture composed of a nano-nucleating agent and a nano-regulator for use in shotcrete systems using high-defect tunnel slag aggregate. This material strengthens the ITZ (interfacial transition zone between cement matrix and aggregate) structure through the micro-filling effect and pozzolanic activity of the nano-nucleating agent, and optimizes the thixotropic properties of the slurry, resulting in good pumpability during spraying, a rapid increase in viscosity upon impact for low rebound, and rapid stabilization upon settling to prevent slurry loss. Simultaneously, the innovative introduction of a nano-regulator provides excellent dispersibility for the nano-nucleating agent. This invention aims to promote the in-depth application of nano-modification technology in hydraulic tunnel support and provide key technical support for the high-value utilization of high-defect tunnel slag aggregate.

[0006] The above background information is disclosed only to assist in understanding the inventive concept and technical solution of this invention patent. It does not necessarily belong to the prior art of this invention. In the absence of clear evidence that the above content was disclosed on the filing date of this invention, the above background information should not be used to evaluate the novelty and inventiveness of this invention. Summary of the Invention

[0007] This invention addresses the technical problems of existing shotcrete, which easily leads to insufficient slurry bonding and weakened mechanical interlocking between aggregates in fresh concrete, thus disrupting the required balance of "adhesion-cohesion-flexibility" properties and causing severe rebound and slurry loss. It provides a nano-modified anti-rebound full-cavity slag shotcrete.

[0008] The shotcrete with full-cavity slag provided by this invention not only uses amorphous slag aggregate as raw material, but also significantly reduces energy consumption in slag aggregate processing, reduces cement usage in concrete, lowers construction costs, and reduces heat of hydration in concrete. In this system, the synergistic effect of nano-nucleating agents (a blend of nano-kaolin and nano-silica) and nano-regulators (precision PCE (PCE is a polycarboxylate superplasticizer) solution: precision PCE is a copolymer of TPEG (polyethylene glycol monomethyl ether methacrylate) macromonomer and acrylic acid, with a small amount of acrylamide introduced as a functional monomer, and polyether-modified polysiloxane as a surfactant and ammonium persulfate as an initiator) and nano-kaolin provides sufficient thixotropy and water retention to prevent water loss during concrete spraying. Rebound and dripping; nano-silica particles penetrate the pores of the ITZ (interfacial transition zone between cement matrix and aggregate), significantly reducing the total porosity of shotcrete and refining the pore size. Simultaneously, they consume the CH (calcium hydroxide) enriched in the ITZ, generating high-strength CSH (calcium silicate hydrate) gel. The high dispersibility of the nano-regulator provides excellent initial dispersion, better encapsulating the nanoparticles, preventing agglomeration, and ensuring uniform distribution within the slurry. This system significantly improves mechanical properties while optimizing the rheological properties of the slurry, enhancing aggregate encapsulation and cohesion, and reducing aggregate-slurry separation during spraying, thereby significantly reducing the rebound rate of shotcrete and improving its density.

[0009] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0010] A nano-modified anti-rebound shotcrete for tunnel slag includes the following raw materials in parts by weight: 665 parts of tunnel slag aggregate, 950 parts of tunnel slag sand, 396-436.5 parts of ordinary Portland cement, 225 parts of water, 10 parts of polycarboxylate superplasticizer, and 8.5 parts of accelerator; the tunnel slag aggregate is further modified by nano-admixtures, wherein the nano-admixtures are composed of nano-kaolin, nano-silica, and a refined PCE solution.

[0011] As a preferred technical solution of the present invention: the amount of the nano-admixture is 1-54 parts; wherein the mass ratio of nano-kaolin, nano-silica and precision PCE solution is 1:1:0.02.

[0012] As a preferred technical solution of the present invention: the precision PCE solution comprises the following components: TPEG-3000, acrylic acid, acrylamide, polyether-modified polysiloxane, and ammonium persulfate; the mass ratio of each component is 300:26:5:1:2.

[0013] As a preferred technical solution of the present invention, the specific preparation method of the precision PCE solution is as follows:

[0014] (1) Add TPEG-3000 macromonomer and appropriate amount of deionized water to a four-necked flask, slowly heat to 30°C and continuously stir magnetically until the system is uniform and transparent to obtain TPEG aqueous solution.

[0015] (2) Premix acrylic acid (AA) and acrylamide (AM) in a beaker and dilute with an appropriate amount of deionized water to prepare an AA-AM mixed monomer aqueous solution; dissolve ammonium persulfate (APS) in deionized water to prepare an initiator solution with a mass fraction of 6.7% for later use;

[0016] (3) Add half the amount of polyether-modified polysiloxane to the above TPEG aqueous solution, and bubble with high-purity nitrogen for 15 min to remove dissolved oxygen. Then heat the reaction system to 80°C and keep it constant. Start to add AA-AM mixed monomer solution dropwise at a uniform rate. After the dropwise addition is completed, continue to keep the reaction at 80°C for 1 h to allow the monomer to fully polymerize. After the reaction is completed, cool the system to below 40°C, add the remaining half of the polyether-modified polysiloxane, and continue to stir for 30 min to disperse evenly. The preparation of the precision PCE solution is then completed.

[0017] As a preferred technical solution of the present invention: the tunnel slag aggregate is made from waste tunnel slag from tunnel excavation as raw material, and after crushing and screening, the tunnel slag aggregate with a particle size of 5-15mm is obtained; the tunnel slag aggregate is modified by stirring nano-kaolin, nano-silica and precision PCE solution evenly.

[0018] As a preferred technical solution of the present invention, the ordinary silicate cement has a specification of P·O42.5.

[0019] As a preferred embodiment of the present invention, the water reduction rate of the polycarboxylate superplasticizer is 25%.

[0020] Compared with the prior art, the advantages and beneficial effects of the present invention include:

[0021] 1. This invention uses nano-admixtures to modify tunnel excavation aggregate to prepare anti-rebound shotcrete, realizing the full-scale resource utilization of tunnel excavation excavation excavation, significantly reducing the demand for natural aggregate mining and the environmental burden of engineering waste, effectively alleviating the problems of land occupation and potential ecological pollution caused by waste dumping, and providing a systematic technical solution for the high-value-added resource utilization of solid waste from tunnel engineering. It is in line with the concept of green and low-carbon construction, and the promotion of this technology will help improve the level of resource recycling in the field of engineering construction.

[0022] 2. This invention uses a nano-admixture, formulated with nano-kaolin and nano-silica precision PCE solution, to strengthen the interface between the aggregate and slurry in tunnel slag, significantly improving the cohesiveness and encapsulation of concrete. It can reduce the rebound rate of spraying to below 10%, greatly improving construction efficiency and reducing material waste. The impermeability grade reaches W8, and the frost resistance grade reaches F50. At the same time, the nano-effect promotes the hydration reaction and optimizes the microstructure, which greatly improves the cubic compressive strength and splitting tensile strength of concrete, significantly enhancing its crack resistance and meeting the durability performance design index. It is especially suitable for the support of hydraulic tunnels in high-stress and high-humidity environments.

[0023] 3. The nano-modified anti-rebound full-tunnel slag shotcrete developed in this invention not only has superior mechanical properties, but also better construction friendliness and environmental adaptability. It can be widely used in the support structures of highway tunnels, railway tunnels, water conservancy tunnels and various underground engineering projects, and has significant technological advancement, economic benefits and engineering promotion value. Attached Figure Description

[0024] Figure 1 The images are of the cut-off material from the drill-and-blast method. In the images, (a) is a picture of the tunnel excavation, (b) is the overall morphology of the cut-off material, (c) is a partial morphology of the cut-off material 1, and (d) is a partial morphology of the cut-off material 2.

[0025] Figure 2 The graph shows the relationship between compressive strength and age for different amounts of nano-admixtures.

[0026] Figure 3 The relationship between splitting tensile strength and age for different amounts of nano-doped materials;

[0027] Figure 4 The graph shows the relationship between compressive strength and age for different nano-admixture components.

[0028] Figure 5 The figure shows the relationship between splitting tensile strength and age for different nano-admixture components. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] The precision PCE solution described in the following examples comprises the following components: TPEG-3000, acrylic acid, acrylamide, polyether-modified polysiloxane, and ammonium persulfate; the mass ratio of each component is 300:26:5:1:2.

[0031] The specific preparation method of the precision PCE solution is as follows:

[0032] (1) Add TPEG-3000 macromonomer and appropriate amount of deionized water to a four-necked flask, slowly heat to 30°C and continuously stir magnetically until the system is uniform and transparent to obtain TPEG aqueous solution.

[0033] (2) Premix acrylic acid (AA) and acrylamide (AM) in a beaker and dilute with an appropriate amount of deionized water to prepare an AA-AM mixed monomer aqueous solution; dissolve ammonium persulfate (APS) in deionized water to prepare an initiator solution with a mass fraction of 6.7% for later use;

[0034] (3) Add half the amount of polyether-modified polysiloxane to the above TPEG aqueous solution, and bubble with high-purity nitrogen for 15 min to remove dissolved oxygen. Then heat the reaction system to 80°C and keep it constant. Start to add AA-AM mixed monomer solution dropwise at a uniform rate. After the dropwise addition is completed, continue to keep the reaction at 80°C for 1 h to allow the monomer to fully polymerize. After the reaction is completed, cool the system to below 40°C, add the remaining half of the polyether-modified polysiloxane, and continue to stir for 30 min to disperse evenly. The preparation of the precision PCE solution is then completed.

[0035] Example 1

[0036] A nano-modified anti-rebound shotcrete made from tunnel slag is composed of the following raw materials in parts by weight: 665 parts of tunnel slag aggregate, 950 parts of tunnel slag sand, 436.5 parts of ordinary Portland cement, 225 parts of water, 10 parts of polycarboxylate superplasticizer, and 8.5 parts of accelerator; the tunnel slag aggregate is further modified by 13.5 parts of nano-admixtures.

[0037] The nano-admixture is composed of nano-kaolin, nano-silica, and a precision PCE solution in a mass ratio of 1:1:0.02; the ordinary silicate cement has a specification of P·O42.5; the polycarboxylate superplasticizer is PCV-9 polycarboxylate superplasticizer with a water reduction rate of 25%; and the accelerator is SBT-N accelerator.

[0038] The tunnel muck aggregate is made from waste tunnel muck excavated from tunnels, which is crushed and screened to obtain aggregate with a particle size of 5-15mm. Images of the tunnel muck aggregate are shown below. Figure 1 As shown in the figure, (a) is a picture of the tunnel excavation, (b) is the overall morphology of the tunnel muck, (c) is the partial morphology of the tunnel muck 1, and (d) is the partial morphology of the tunnel muck 2.

[0039] Example 2

[0040] A nano-modified anti-rebound shotcrete made from tunnel slag is composed of the following raw materials in parts by weight: 665 parts of tunnel slag aggregate, 950 parts of tunnel slag sand, 423 parts of ordinary Portland cement, 225 parts of water, 10 parts of polycarboxylate superplasticizer, and 8.5 parts of accelerator; the tunnel slag aggregate is further modified by 27 parts of nano-admixtures.

[0041] The nano-admixture is composed of nano-kaolin, nano-silica, and a precision PCE solution in a mass ratio of 1:1:0.02; the ordinary silicate cement has a specification of P·O42.5; the polycarboxylate superplasticizer is PCV-9 polycarboxylate superplasticizer with a water reduction rate of 25%; and the accelerator is SBT-N accelerator.

[0042] Example 3

[0043] A nano-modified anti-rebound shotcrete made from tunnel slag is composed of the following raw materials in parts by weight: 665 parts of tunnel slag aggregate, 950 parts of tunnel slag sand, 409.5 parts of ordinary Portland cement, 225 parts of water, 10 parts of polycarboxylate superplasticizer, and 8.5 parts of accelerator; the tunnel slag aggregate is further modified by 40.5 parts of nano-admixtures.

[0044] The nano-admixture is composed of nano-kaolin, nano-silica, and a precision PCE solution in a mass ratio of 1:1:0.02; the ordinary silicate cement has a specification of P·O42.5; the polycarboxylate superplasticizer is PCV-9 polycarboxylate superplasticizer with a water reduction rate of 25%; and the accelerator is SBT-N accelerator.

[0045] Example 4

[0046] A nano-modified anti-rebound shotcrete made from tunnel slag is composed of the following raw materials in parts by weight: 665 parts of tunnel slag aggregate, 950 parts of tunnel slag sand, 396 parts of ordinary Portland cement, 225 parts of water, 10 parts of polycarboxylate superplasticizer, and 8.5 parts of accelerator; the tunnel slag aggregate is further modified by 54 parts of nano-admixtures.

[0047] The nano-admixture is composed of nano-kaolin, nano-silica, and a precision PCE solution in a mass ratio of 1:1:0.02; the ordinary silicate cement has a specification of P·O42.5; the polycarboxylate superplasticizer is PCV-9 polycarboxylate superplasticizer with a water reduction rate of 25%; and the accelerator is SBT-N accelerator.

[0048] Comparative Example 1

[0049] A type of shotcrete with full tunnel slag is composed of the following raw materials in parts by weight: 665 parts of tunnel slag aggregate, 950 parts of tunnel slag sand, 450 parts of ordinary Portland cement, 225 parts of water, 10 parts of polycarboxylate superplasticizer, and 8.5 parts of quick-setting agent.

[0050] The ordinary silicate cement has a specification of P·O42.5, the polycarboxylate superplasticizer is PCV-9 polycarboxylate superplasticizer with a water reduction rate of 25%, and the accelerator is SBT-N accelerator.

[0051] Comparative Example 2

[0052] A nano-modified anti-rebound shotcrete made from tunnel slag is composed of the following raw materials in parts by weight: 665 parts of tunnel slag aggregate, 950 parts of tunnel slag sand, 423 parts of ordinary Portland cement, 225 parts of water, 10 parts of polycarboxylate superplasticizer, and 8.5 parts of accelerator; the tunnel slag aggregate is further modified by 27 parts of nano-admixtures.

[0053] The nano-admixture is composed of nano-kaolin and nano-silica in a 1:1 mass ratio. The ordinary silicate cement has a specification of P·O42.5, the polycarboxylate superplasticizer is PCV-9 polycarboxylate superplasticizer with a water reduction rate of 25%, and the accelerator is SBT-N accelerator.

[0054] Comparative Example 3

[0055] A nano-modified anti-rebound shotcrete made from tunnel slag is composed of the following raw materials in parts by weight: 665 parts tunnel slag aggregate, 950 parts tunnel slag sand, 423 parts ordinary Portland cement, 225 parts water, 10 parts polycarboxylate superplasticizer, and 8.5 parts accelerator. The tunnel slag aggregate is further modified by 27 parts of nano-admixtures. The nano-admixtures consist of nano-kaolin and a refined PCE solution at a mass ratio of 1:0.02. The ordinary Portland cement has a P·O42.5 specification, the polycarboxylate superplasticizer is PCV-9 polycarboxylate superplasticizer with a water reduction rate of 25%, and the accelerator is SBT-N accelerator.

[0056] Comparative Example 4

[0057] A nano-modified anti-rebound shotcrete made from tunnel slag is composed of the following raw materials in parts by weight: 665 parts of tunnel slag aggregate, 950 parts of tunnel slag sand, 423 parts of ordinary Portland cement, 225 parts of water, 10 parts of polycarboxylate superplasticizer, and 8.5 parts of accelerator; the tunnel slag aggregate is further modified by 27 parts of nano-admixtures.

[0058] The nano-admixture is composed of nano-silica and a precision PCE solution at a mass ratio of 1:0.02. The ordinary silicate cement has a specification of P·O42.5, the polycarboxylate superplasticizer is PCV-9 polycarboxylate superplasticizer with a water reduction rate of 25%, and the accelerator is SBT-N accelerator.

[0059] Comparative Example 5

[0060] A nano-modified anti-rebound shotcrete made from tunnel slag is composed of the following raw materials in parts by weight: 665 parts of tunnel slag aggregate, 950 parts of tunnel slag sand, 423 parts of ordinary Portland cement, 225 parts of water, 10 parts of polycarboxylate superplasticizer, and 8.5 parts of accelerator; the tunnel slag aggregate is further modified by 27 parts of nano-admixtures.

[0061] The nano-admixture is composed of nano-kaolin, nano-silica, and a precision PCE solution in a mass ratio of 1:1:0.04; the ordinary silicate cement has a specification of P·O42.5; the polycarboxylate superplasticizer is PCV-9 polycarboxylate superplasticizer with a water reduction rate of 25%; and the accelerator is SBT-N accelerator.

[0062] That is, Comparative Example 1 has the same concrete composition as Examples 1, 2, 3, and 4, but no nano-admixtures were added for modification in the comparative example. The amount of nano-admixtures in Examples 1, 2, 3, and 4 is different. Compared with Example 2, Comparative Example 2 did not add precise PCE solution to the nano-admixture. Compared with Example 2, Comparative Example 3 did not add nano-kaolin in the nano-admixture. Compared with Example 2, Comparative Example 4 did not add nano-silica in the nano-admixture. Compared with Example 2, Comparative Example 5 has a different composition ratio of nano-kaolin, nano-silica, and precise PCE solution in the novel nano-admixture.

[0063] The preparation methods of the sprayed concrete described in Examples 1-4 and Comparative Examples 1-5 are as follows: Weigh the coarse and fine aggregates of the slag and half of the cement, and dry mix for 60-90 seconds. Mix the nano-admixture with the remaining half of the cement evenly beforehand, and then put it into the mixing pot and continue to dry mix for 60 seconds to ensure that the nano-scale materials are dispersed. Dissolve the high-efficiency water-reducing agent and the quick-setting agent in most of the mixing water, pour the liquid into the mixture in the mixing at a uniform speed, and pour it out after stirring for three minutes.

[0064] The shotcrete prepared in Examples 1-4 and Comparative Examples 1-5 of this invention was used to prepare specimens of corresponding sizes according to the requirements of the "Test Procedure for Hydraulic Concrete" (SL / T 352-2020). The novel nano-admixture modified anti-rebound full-cavity slag shotcrete of the above examples and comparative examples was used to test its rebound rate, cubic compressive strength, splitting tensile strength, impermeability, and frost resistance. The results are shown in Table 1 and Appendix. Figure 2-5 As shown; among which attached Figure 2 Figure 1 shows the relationship between cubic compressive strength and age for different amounts of nano-admixtures; (Attached) Figure 3 The relationship between splitting tensile strength and age for different amounts of nano-doped materials; Figure 4 The graph shows the relationship between cubic compressive strength and age for different nano-admixture components (Example 2 and Comparative Examples 2 to 5); Figure 5The graph shows the relationship between splitting tensile strength and age for different nano-admixture components (Example 2 and Comparative Examples 2 to 5).

[0065] Table 1: Performance of Novel Nano-Admixture Modified Anti-Rebound Shotcrete with Different Formulations

[0066]

[0067] From Table 1 and the instruction manual appendix Figure 2-5 The results show that when the dosage of the nano-admixture used in this invention is 6%, and the ratio of nano-kaolin, nano-silica and precision PCE solution in the nano-admixture is 1:1:0.02 (Example 2), the performance reaches the best, the synergistic effect between the components is the best, the rebound rate is reduced to 7%, the cubic compressive strength and splitting tensile strength are better than other dosages, and the impermeability and freeze-thaw resistance are good.

[0068] The above description, in conjunction with specific / preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the inventive concept, and all such substitutions or modifications should be considered within the scope of protection of the present invention.

Claims

1. A nano-modified anti-rebound shotcrete for full-cavity slag filling, characterized in that: It is composed of the following raw materials in parts by weight: 665 parts of cave slag aggregate, 950 parts of cave slag sand, 396-436.5 parts of ordinary Portland cement, 225 parts of water, 10 parts of polycarboxylate superplasticizer, and 8.5 parts of quick-setting agent; the cave slag aggregate is also modified by nano-admixtures, wherein the nano-admixtures are composed of nano-kaolin, nano-silica, and precision PCE solution; The amount of the nano-admixture is 1-54 parts; wherein the mass ratio of nano-kaolin, nano-silica and precision PCE solution is 1:1:0.

02. The precision PCE solution comprises the following components: TPEG-3000, acrylic acid, acrylamide, polyether-modified polysiloxane, and ammonium persulfate; The mass ratio of TPEG-3000, acrylic acid, acrylamide, polyether-modified polysiloxane, and ammonium persulfate in the precision PCE solution is 300:26:5:1:

2. The specific preparation method of the precision PCE solution is as follows: (1) Add TPEG-3000 and an appropriate amount of deionized water to a four-necked flask, slowly heat to 30°C and continuously stir magnetically until the system is uniform and transparent to obtain TPEG aqueous solution. (2) Premix acrylic acid and acrylamide in a beaker and dilute with an appropriate amount of deionized water to prepare a mixed monomer aqueous solution; dissolve ammonium persulfate in deionized water to prepare an initiator solution with a mass fraction of 6.7% for later use; (3) Add half the amount of polyether-modified polysiloxane to the above TPEG aqueous solution, and bubble with high-purity nitrogen for 15 min to remove dissolved oxygen. Then heat the reaction system to 80°C and keep it constant. Start to add the mixed monomer aqueous solution at a uniform rate. After the addition is completed, continue to keep the reaction at 80°C for 1 h to allow the monomer to fully polymerize. After the reaction is completed, cool the system to below 40°C, add the remaining half of the polyether-modified polysiloxane, and continue to stir for 30 min to disperse evenly. The preparation of the precision PCE solution is then completed. The tunnel slag aggregate is made from waste tunnel slag excavated from tunnels, which is crushed and screened to obtain tunnel slag aggregate with a particle size of 5-15mm. The ordinary silicate cement has a specification of P·O42.5; The water reduction rate of the polycarboxylate superplasticizer is 25%; The TPEG-3000 is polyethylene glycol monomethyl ether methacrylate.

Images