Flowable fill material and method of making same

Abstract

The application discloses a kind of flow state filling materials and preparation method thereof, flow state filling material includes the following weight parts of raw material components: argillaceous siltstone shield muck is 80-95 parts by dry weight, recycled micro powder is 5-20 parts, granulated blast furnace slag is 3-20 parts, fly ash is 1-10 parts, cement clinker is 1-10 parts, industrial byproduct gypsum is 0.2-2 parts, silica fume is 0.5-2 parts, tung oil is 1-6 parts, cellulose ether is 0.1-0.4 parts, water reducing agent is 0.1-0.7 parts, dispersing agent is 0.1-0.7, activator is 0.5-2 parts, the flow state filling material not only realizes argillaceous siltstone shield muck, recycled micro powder and other solid waste high-mixing amount resource utilization, but also has the advantages of good fluidity, low bleeding rate, short setting time, high early strength, low shrinkage and not easy to crack.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular, to a fluidized filler material and its preparation method. Background Technology

[0002] Shield tunneling excavation waste is a fluid plastic soil with high water content, high viscosity, and low permeability generated during the tunneling process of a tunnel boring machine (TBM). Currently, for shield tunneling waste with high sand and gravel content and high quality, sand washing and sand making are commonly used for resource utilization; for shield tunneling waste with high clay content, landfill disposal is the main method. Muddy siltstone shield tunneling waste is mainly composed of silt and clay, with silt content not less than 50% and clay content ranging from 25% to 50%. However, because muddy siltstone is prone to disintegration and softening when exposed to water, and its strength decreases rapidly, it is not suitable as aggregate for concrete and mortar, resulting in a very low resource utilization rate.

[0003] Fluidized solidified soil is a filling material with good fluidity, made primarily from excavated soil and a solidifying agent. Water is added and stirred until homogeneous. It can be used for backfilling in projects such as trenches, mined-out areas, foundation pits, pipe trenches, and pipe galleries. Compared to traditional manual rammed earth backfilling, fluidized solidified soil offers advantages such as faster construction speed, higher strength, and controllable quality. However, because the main raw material of fluidized solidified soil is clay, which has high viscosity and strong water absorption capacity, the amount of water used for mixing far exceeds the amount required for the hydration of the solidifying agent to achieve good fluidity. This results in severe bleeding after filling, long setting time, low early strength, high shrinkage rate, and easy cracking, seriously affecting construction progress and project quality.

[0004] Therefore, how to provide a fluidized filler material with high fluidity, low bleeding rate, short setting time, high early strength, low shrinkage rate, and resistance to cracking, as well as its preparation method, is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention provides a fluidized filling material and its preparation method to solve the problems of existing fluidized solidified soil, such as severe bleeding, long setting time, low early strength, large shrinkage rate, and easy cracking.

[0006] According to one aspect of the present invention, a fluidized filler material is provided, comprising the following raw material components in parts by weight: 80-95 parts of silty mudstone shield tunnel slag (dry weight), 5-20 parts of recycled micro powder, 3-20 parts of granulated blast furnace slag, 1-10 parts of fly ash, 1-10 parts of cement clinker, 0.2-2 parts of industrial by-product gypsum, 0.5-2 parts of silica fume, 1-6 parts of tung oil, 0.1-0.4 parts of cellulose ether, 0.1-0.7 parts of water-reducing agent, 0.1-0.7 parts of dispersant, and 0.5-2 parts of activator, wherein the silty mudstone shield tunnel slag comprises silt and clay, and the mass percentage of silt is not less than 50%; the recycled micro powder is recycled waste concrete micro powder; and the water-reducing agent is polymethyl methacrylate-methacrylic acid copolymer.

[0007] Further, the raw material components include the following parts by weight: 85-95 parts of muddy siltstone shield tunnel slag (dry weight), 5-15 parts of recycled micro powder, 5-15 parts of granulated blast furnace slag, 1-5 parts of fly ash, 2-8 parts of cement clinker, 0.3-1.5 parts of industrial by-product gypsum, 0.5-1 parts of silica fume, 3-5 parts of tung oil, 0.1-0.2 parts of cellulose ether, 0.1-0.5 parts of water-reducing agent, 0.1-0.5 parts of dispersant, and 0.5-1.5 parts of activator.

[0008] Furthermore, the residue of the recycled waste concrete powder after sieving through a 45μm square-hole sieve does not exceed 30%.

[0009] Furthermore, the specific surface area of ​​the granulated blast furnace slag is not less than 400 m². 2 / kg.

[0010] Furthermore, the fly ash residue after passing through a 45μm square-hole sieve does not exceed 30%; and / or, the silica fume has a specific surface area of ​​not less than 15m². 2 / g.

[0011] Furthermore, the mineral composition of the industrial by-product gypsum includes CaSO4·2H2O and / or CaSO4; and / or,

[0012] The industrial by-product gypsum is one or more of the following: desulfurized gypsum, phosphogypsum, fluorogypsum, citric acid gypsum, and titanium gypsum.

[0013] Furthermore, the tung oil is natural, boiled tung oil.

[0014] Further, the cellulose ether comprises one or more of methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, and hydroxypropyl methylcellulose; and / or,

[0015] The dispersant comprises one or more of sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, sodium carbonate, sodium phosphate, and sodium oxalate; and / or,

[0016] The activator includes one or more of NaOH, Na2SiO3, Na2SO4, and Na2CO3.

[0017] According to another aspect of the present invention, a method for preparing the above-mentioned fluidized filling material is also provided, comprising the following steps:

[0018] The silty mudstone shield tunneling excavation soil is crushed to an average particle size of no more than 2 mm, and then tung oil is mixed evenly with the crushed silty mudstone shield tunneling excavation soil to obtain modified silty mudstone shield tunneling soil.

[0019] Cement clinker is ground into fine powder to obtain finely ground cement clinker.

[0020] The finely ground cement clinker is mixed evenly with recycled micro powder, granulated blast furnace slag, fly ash, industrial by-product gypsum, silica fume, and activator to obtain a composite curing agent;

[0021] First, the water-reducing agent, dispersant and modified silty mudstone shield tunnel slag are mixed together, then the composite curing agent is added and mixed together, and finally the cellulose ether is added and mixed together to obtain the fluid filling material.

[0022] Furthermore, the cement clinker includes silicate cement clinker, sulfoaluminate cement clinker, or a mixture of silicate cement clinker and sulfoaluminate cement clinker, wherein the silicate cement clinker, after fine grinding, has a specific surface area of ​​not less than 350 m². 2 / kg, the specific surface area of ​​the finely ground sulfoaluminate cement clinker is not less than 400m². 2 / kg; the spread of the fluidized filling material is not less than 1000mm.

[0023] The present invention has the following beneficial effects:

[0024] This invention uses silty mudstone shield tunneling slag as the main raw material and employs recycled micro powder, granulated blast furnace slag, fly ash and other active waste residues as cementing materials to co-solidify the shield tunneling slag and prepare a fluid filling material. The shield tunneling slag accounts for more than 90% of the total mass, and the total solid waste accounts for more than 99%, realizing the high-content resource utilization of silty mudstone shield tunneling slag, recycled micro powder and other solid wastes.

[0025] The fluidized bed filling material of this invention uses silty mudstone shield tunneling slag as the main raw material. The silty mudstone shield tunneling slag contains a large amount of silt, which not only acts as a skeleton but also reduces the viscosity of the filling material, thereby improving its rheological properties. At the same time, the fluidized bed filling material of this invention uses tung oil to modify the shield tunneling slag. The tung oil adheres to the surface of the clay particles, forming a tung oil film coating, which not only weakens its water adsorption capacity and the water film binding effect between particles, making the bound water film thinner and releasing free water, but also reduces the friction between aggregates and improves its rheological properties. In addition, the water-reducing agent added to the fluidized bed filling material of this invention has good compatibility with clay and works synergistically with the dispersant to achieve a good water-reducing and dispersing effect. The fluid filler material of this invention uses silty mudstone shield tunnel slag as the main raw material, modifies it with tung oil, and adds water-reducing agents and dispersants that are compatible with clay. Through the ball-bead effect of silt, the hydrophobic modification and lubrication of clay by tung oil, and the water-reducing and dispersing effects of water-reducing agents and dispersants, the adsorption capacity of clay to water is weakened and its rheological properties are improved. Thus, while ensuring the high fluidity of the filler material, the amount of mixing water is reduced, thereby reducing the bleeding rate of the filler material, shortening its setting time, reducing its shrinkage and cracking, and improving its strength.

[0026] The fluidized filler material of this invention uses recycled micro powder, granulated blast furnace slag, fly ash, cement clinker, industrial by-product gypsum, silica fume, and an activator as a composite cementitious material. The recycled micro powder mainly consists of hardened cement stone, unhydrated particles, and ground sand and stone aggregate. During the hydration process of cement clinker, it exhibits a nucleation effect, accelerating the formation of Ca(OH)₂, CSH, and CAH, and promoting the reaction of tricalcium aluminate with sulfate, thereby improving the early strength of the filler material. The granulated blast furnace slag, fly ash, and recycled micro powder possess pozzolanic activity. Under alkaline conditions and with the aid of the activator, they can rapidly undergo hydration reactions to generate cementitious substances such as CSH, CAH, CASH, and NASH, further enhancing the early strength of the filler material. The synergistic effect of the raw materials in the above-mentioned composite cementitious material enables it to undergo rapid hydration reactions, resulting in high early strength. Therefore, the fluidized filler material of this invention has the advantages of short setting time and high early strength, which can shorten the construction cycle.

[0027] The fluidized bed material of this invention uses silty mudstone shield tunneling slag as the main raw material. The silty mudstone shield tunneling slag contains a large amount of silt, which acts as a good skeleton in the hardened body, thereby limiting the drying shrinkage of the bed material. The fluidized bed material of this invention uses recycled micro-powder, granulated blast furnace slag, fly ash, cement clinker, industrial by-product gypsum, silica fume, and an activator as a composite cementitious material. Compared with ordinary silicate cement, it has low chemical shrinkage and micro-expansion characteristics, which can further reduce the shrinkage rate of the bed material. The fluidized bed material of this invention uses tung oil-modified shield tunneling slag, which improves the hydrophobicity of clay minerals. Under the same fluidity conditions, it can reduce the amount of water used for mixing the bed material. At the same time, the addition of water-reducing agents and dispersants can further reduce the amount of water used in the bed material, thereby significantly reducing its drying shrinkage. Therefore, the fluidized bed material of this invention has the advantages of low shrinkage and resistance to cracking.

[0028] The fluidized filler material of this invention uses silty mudstone shield tunneling excavation soil as the main raw material. Tung oil is used to modify the shield tunneling excavation soil, and water-reducing agents and dispersants with good compatibility with clay are added, significantly reducing the amount of water required for mixing the filler material. Simultaneously, a small amount of cellulose ether is added to improve the water retention of the mixed slurry. By reducing the amount of water required for mixing and improving the water retention of the mixed slurry, the bleeding rate of the filler material decreases, and the evaporation rate of water is slowed down, thus reducing cracking.

[0029] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0030] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0031] Figure 1 This is a diagram showing the state of the fluidized filling material prepared in Example 1 before it fully hardens after backfilling the trough;

[0032] Figure 2 This is a diagram showing the hardened state of the fluid filling material prepared in Example 1 after backfilling the trough. Detailed Implementation

[0033] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0034] One embodiment of this application provides a fluid filling material composed of silty mudstone shield tunneling slag, comprising the following raw material components by weight: 80-95 parts silty mudstone shield tunneling slag (dry weight), 5-20 parts recycled micro powder, 3-20 parts granulated blast furnace slag, 1-10 parts fly ash, 1-10 parts cement clinker, 0.2-2 parts industrial by-product gypsum, 0.5-2 parts silica fume, 1-6 parts tung oil, 0.1-0.4 parts cellulose ether, 0.1-0.7 parts water-reducing agent, 0.1-0.7 parts dispersant, and 0.5-2 parts activator. The silty mudstone shield tunneling slag comprises silt and clay, with the silt comprising not less than 50% by weight. The recycled micro powder is recycled waste concrete micro powder. The water-reducing agent is polymethyl methacrylate-methacrylic acid copolymer.

[0035] In the embodiments of this application, the muddy siltstone shield tunneling muck is the original shield tunneling muck generated during the tunneling process of the shield machine.

[0036] According to the embodiments of this application, cement clinker undergoes a hydration reaction upon contact with water. The Ca(OH)2 contained in the recycled powder and the unhydrated cement particles can hydrate to form calcium aluminate and calcium silicate, becoming nuclei for cement clinker hydration, accelerating the hydration reaction and increasing the density of the cement stone. As the cement clinker hydration reaction continues, the pH value of the mixed slurry increases. Under the synergistic effect of the alkaline environment and activator, the recycled powder, granulated blast furnace slag, and fly ash react rapidly to generate cementitious substances such as CSH, CAH, CASH, and NASH. During the reaction of cement clinker, recycled powder, granulated blast furnace slag, and fly ash, Ca is released. 2+ Al 3+ High-valence cations, and Na adsorbed on the surface of clay particles + K + Ion exchange reduces the zeta potential on the surface and decreases the thickness of the electric double layer, causing clay particles to gradually aggregate. Gel substances such as CSH, CAH, CASH, and NASH bind clay particles and silt together. As water is continuously consumed and lost, the concentration of Ca(OH)2 in the pore solution increases. In an alkaline environment, the active mineral components in the clay particles react with hydration gels such as CSH and CAH to form plate-like, fibrous, or needle-like crystals, further increasing the connection between particles and hydration gels, forming a stable network structure.

[0037] The carbon aluminates formed by the reaction of recycled micro powder with cement clinker hydration products can inhibit the conversion of type III calcium sulfoaluminate (AFt) to type I calcium sulfoaluminate (AFm). Recycled micro powder also has a micro-aggregate effect, which can form a macro-fine continuous gradation with silt and sand, playing a skeleton role in the hardening of filler materials, which is beneficial to improving the strength of the hardened body and limiting its shrinkage. Silica fume has extremely strong pozzolanic activity and can react with Ca(OH)2 to form CSH gel, thereby improving the pore structure of the hardened body, reducing macropores and increasing micropores. Industrial by-product gypsum reacts with CAH to form type III calcium sulfoaluminate, which has the characteristics of micro-expansion, can fill the pores in the hardened body, improve its density, and reduce its shrinkage and cracking.

[0038] Tung oil adheres to the surface of clay particles, forming a tung oil film coating. This improves the hydrophobicity of the clay and enhances its rheological properties, thereby reducing the amount of water needed for mixing the filler material and consequently decreasing the drying shrinkage of the hardened body. Simultaneously, tung oil possesses high polymerization reactivity and excellent film-forming properties. It can form a tung oil film on the surface of clay particles, strengthening the bonding force between them. It can also react with Ca(OH)₂ to produce calcium carboxylate salts, which synergistically solidify with gelling substances such as CSH and CAH, resulting in a refined pore structure and increased strength in the hardened body. Furthermore, the tung oil film can interrupt the capillary channels of the hardened body, improving… The hardened body exhibits improved water permeability; the dispersant increases the thickness of the double electric layer of clay particles, increases the repulsive force between clay particles' edges and faces or edges, prevents clay particles from contacting each other, and maintains the dispersed structure of clay particles; the water-reducing agent has a linear structure, which can be fully adsorbed on the surface of solid particles, hindering the collision and aggregation caused by the thermal motion of particles, promoting the dispersion of particles, and releasing the encapsulated free water, thereby effectively improving the fluidity of the slurry; the synergistic effect of tung oil, dispersant, and water-reducing agent significantly reduces the amount of mixing water, lowers the water-cement ratio of the composite cementitious material, and greatly improves the strength of the hardened body.

[0039] Cellulose ethers have thickening and water-retaining effects, which can improve the cohesiveness of the mixture slurry, reduce segregation and bleeding of the mixture slurry, and reduce the rate of water evaporation, thus helping to reduce cracking.

[0040] The synergistic effect among the above raw materials enables the obtained fluidized filler material to have advantages such as high fluidity, low bleeding rate, short setting time, high strength, low shrinkage rate, and resistance to cracking.

[0041] According to an embodiment of this application, the expansion of the fluidized filling material is not less than 1000 mm.

[0042] According to the embodiments of this application, the fluid filling material can be applied to backfilling of trenches, goaf areas, foundation pits, pipe corridors, and synchronous grouting of shield tunnels. It has the advantages of good fluidity, low bleeding rate, short setting time, high strength, low shrinkage rate, and resistance to cracking, which can improve construction efficiency, shorten the construction cycle, and ensure project quality.

[0043] In the embodiments of this application, the content of each raw material in the fluidized filling material is further optimized to achieve better comprehensive performance. Specifically, it includes the following raw material components in parts by weight: 85-95 parts of muddy siltstone shield tunnel slag (dry weight), 5-15 parts of recycled micro powder, 5-15 parts of granulated blast furnace slag, 1-5 parts of fly ash, 2-8 parts of cement clinker, 0.3-1.5 parts of industrial by-product gypsum, 0.5-1 parts of silica fume, 3-5 parts of tung oil, 0.1-0.2 parts of cellulose ether, 0.1-0.5 parts of water-reducing agent, 0.1-0.5 parts of dispersant, and 0.5-1.5 parts of activator.

[0044] In the embodiments of this application, the silty mudstone shield tunneling excavation soil includes silt and clay, and the mass percentage of silt is not less than 50%.

[0045] According to the embodiments of this application, the aforementioned shield tunneling excavation soil is silty mudstone, mainly composed of silt and clay. Because clay has high viscosity and strong water absorption capacity, to achieve good fluidity in the solidified soil, a much higher amount of water than required for the hydration of the solidifying agent needs to be added. This excess water will gradually evaporate after filling, causing severe shrinkage and cracking of the hardened body. The silty mudstone shield tunneling excavation soil has a silt content of not less than 50%. The ball-bearing effect of the silt can effectively improve the workability of the clay, reduce its mixing water consumption, and also act as a skeleton during the hardening process, limiting the shrinkage of the hardened body and improving its strength.

[0046] In the embodiments of this application, the water-reducing agent is polymethyl methacrylate-methacrylic acid copolymer.

[0047] According to the embodiments of this application, the above-mentioned polymethyl methacrylate-methacrylic acid copolymer molecules have a linear structure and extremely short molecular side chains, which can effectively avoid the side chains from chemically embedding into the interlayer of clay minerals, causing a reduction in the effective concentration of the water-reducing agent in the liquid phase, and weakening or even losing the water-reducing effect; the above-mentioned water-reducing agent can be fully adsorbed on the surface of cement and clay particles, hindering the collision and aggregation caused by the thermal motion of particles, and promoting the dispersion of particles.

[0048] In the embodiments of this application, the waste concrete recycled powder has a residue of no more than 30% after being sieved through a 45μm square hole sieve.

[0049] According to embodiments of this application, the aforementioned recycled waste concrete powder mainly consists of hardened cement paste, unhydrated particles, and ground sand and aggregate. Due to the low content of unhydrated clinker after long-term hydration, the recycled powder, which has an extremely high paste content, also has a low activity index. Mechanical grinding not only disrupts its crystal structure and introduces defects or other metastable characteristics, but also effectively improves its particle morphology, reduces surface cracks, and exposes the unhydrated internal portion, thereby effectively increasing its activity index. When the recycled powder leaves no more than 30% residue on a 45μm square-hole sieve, it exhibits high activity.

[0050] In the embodiments of this application, the specific surface area of ​​the granulated blast furnace slag is not less than 400 m². 2 / kg.

[0051] In the embodiments of this application, the fly ash residue after sieving through a 45μm square-hole sieve does not exceed 30%; and / or, the silica fume has a specific surface area of ​​not less than 15m². 2 / g.

[0052] According to embodiments of this application, the aforementioned granulated blast furnace slag and fly ash possess potential hydration activity, but their hydration reaction is very slow. To meet early strength requirements, it is necessary to improve their activity. Methods to improve their activity mainly include mechanical activation and chemical activation. Mechanical activation refers to grinding the powder to change the particle size, shape, and chemical bond strength, thereby increasing its specific surface area and surface energy, and thus improving its activity. When the specific surface area of ​​the blast furnace slag is not less than 400 m²... 2 When the particle size of fly ash is more than 70% less than 45μm, its activity is relatively high. Under the action of alkaline activators, it can react quickly and produce high early strength.

[0053] In the embodiments of this application, the mineral composition of the industrial by-product gypsum includes CaSO4·2H2O and / or CaSO4; and / or, the industrial by-product gypsum is one or more of desulfurized gypsum, phosphogypsum, fluorogypsum, citric acid gypsum, and titanium gypsum.

[0054] According to the embodiments of this application, the industrial by-product gypsum of the above components reacts with CAH in the system to generate an expansive hydration product, ettringite, which can fill the pores in the hardened body structure, improve the density of the hardened body, and also compensate for the shrinkage of the matrix caused by water evaporation, thereby reducing the shrinkage and cracking of the solidified soil.

[0055] In the embodiments of this application, the tung oil is natural boiled tung oil.

[0056] In the embodiments of this application, the main components of the above-mentioned tung oil are tung oil acid and linoleic acid, with very low water content, and it has good hydrophobicity, lubricity and fast drying film formation speed.

[0057] In embodiments of this application, the cellulose ether includes one or more of methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, and hydroxypropyl methylcellulose; and / or,

[0058] The dispersant comprises one or more of sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, sodium carbonate, sodium phosphate, and sodium oxalate; and / or,

[0059] The activator includes one or more of NaOH, Na2SiO3, Na2SO4, and Na2CO3.

[0060] According to the embodiments of this application, the above-mentioned methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, and hydroxypropylmethylcellulose have good thickening and water retention effects, which can improve the cohesiveness of the mixture slurry, reduce the segregation and bleeding of the mixture slurry, and reduce the rate of water evaporation, which is beneficial to reducing cracking.

[0061] According to the embodiments of this application, the above-mentioned sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, sodium carbonate, sodium phosphate and sodium oxalate can increase the double electric layer thickness of clay particles, increase the repulsive force between clay particles side-to-side or side-to-side, prevent clay particles from contacting each other, maintain their dispersed structure, and release the encapsulated free water.

[0062] According to embodiments of this application, the aforementioned NaOH, Na2SiO3, Na2SO4, and Na2CO3 can dissolve the aluminosilicate glass in blast furnace slag and fly ash, releasing Si and Al ions to form free [SiO4]. 4- and [AlO4] 5- This process generates amorphous gels and crystalline structures; with the release of free [SiO4]... 4- and [AlO4] 5- The increase in [SiO4] occurs within a short period of time. 4- and [AlO4] 5- A condensation reaction occurs, generating gel substances such as CASH and NASH, which causes the filler material to solidify and harden rapidly, resulting in high strength.

[0063] Another embodiment of this application provides a method for preparing the above-mentioned fluidized filling material, comprising the following steps:

[0064] The silty mudstone shield tunneling excavation soil is crushed to an average particle size of no more than 2 mm, and then tung oil is mixed evenly with the crushed silty mudstone shield tunneling excavation soil to obtain modified silty mudstone shield tunneling soil.

[0065] Cement clinker is ground into fine powder to obtain finely ground cement clinker.

[0066] The finely ground cement clinker is mixed evenly with recycled micro powder, granulated blast furnace slag, fly ash, industrial by-product gypsum, silica fume, and activator to obtain a composite curing agent;

[0067] First, the water-reducing agent, dispersant and modified silty mudstone shield tunnel slag are mixed together, then the composite curing agent is added and mixed together, and finally the cellulose ether is added and mixed together to obtain the fluid filling material.

[0068] The embodiments of this application involve crushing the silty mudstone shield tunneling excavation soil to an average particle size of no more than 2 mm. This is because the excavated shield tunneling excavation soil often contains large boulders. Crushing it ensures that the particle size remains within a reasonable range, improving the uniformity of the shield tunneling excavation soil particles and helping to guarantee the quality of the filling material. Simultaneously, since the fluid filling material of this application has excellent flowability and is mainly used for pumping during construction, excessively large shield tunneling excavation soil particles are prone to settling during pumping, easily leading to pipe blockage. Mixing tung oil evenly with the crushed silty mudstone shield tunneling excavation soil allows the tung oil to fully and evenly adhere to the surface of the shield tunneling excavation soil particles, changing the clay particles from hydrophilic to hydrophobic, thereby reducing the amount of water adsorbed by the clay and decreasing the amount of water required for mixing. At the same time, the formed tung oil film coating acts as a lubricant, reducing the friction between clay particles and improving its rheological properties.

[0069] In the embodiments of this application, the cement clinker includes silicate cement clinker, sulfoaluminate cement clinker, or a mixture of silicate cement clinker and sulfoaluminate cement clinker, wherein the silicate cement clinker, after fine grinding, has a specific surface area of ​​not less than 350 m². 2 / kg, the specific surface area of ​​the finely ground sulfoaluminate cement clinker is not less than 400m². 2 / kg; the spread of the fluidized filling material is not less than 1000mm.

[0070] According to the embodiments of this application, because the curing agent dosage of the fluidized filler material is relatively low, and its mixing water consumption is much higher than the water consumption required for curing agent hydration, the setting time of the fluidized filler material is relatively long, and its early compressive strength is also relatively low. Silicate cement is made by grinding silicate cement clinker and gypsum retarder. Directly grinding silicate cement clinker can accelerate the hydration rate of the composite curing agent, thereby improving the early strength of the fluidized filler material and shortening its setting time. Sulfoaluminate cement has the characteristics of rapid hardening and micro-expansion, which can improve the early strength of the fluidized filler material, shorten its setting time, and compensate for the shrinkage of the hardened body. The silicate cement clinker and gypsum are ground to a fineness of not less than 350 μm. 2 / kg, grind sulfoaluminate cement clinker to a fineness of not less than 400m³. 2 / kg, finely ground cement clinker can undergo rapid hydration reaction, which helps to shorten the setting time of fluid filler materials and improve their early strength.

[0071] In some embodiments, the method for preparing the above-mentioned fluidized filling material includes the following steps:

[0072] (1) Crush the muddy siltstone shield tunneling slag to a particle size of no more than 2 mm, and then mix tung oil with the crushed muddy siltstone shield tunneling slag evenly to obtain modified muddy siltstone shield tunneling slag with a moisture content of no less than 30%.

[0073] (2) Grind the cement clinker into a fine powder, wherein the specific surface area of ​​the silicate cement clinker is not less than 350 m². 2 / kg, the specific surface area of ​​sulfoaluminate cement clinker is not less than 400m² 2 / kg, to obtain finely ground cement clinker;

[0074] (3) The finely ground cement clinker is mixed evenly with recycled micro powder, granulated blast furnace slag, fly ash, industrial by-product gypsum, silica fume and activator to obtain a composite curing agent;

[0075] (4) First, mix the water-reducing agent, dispersant and modified silty mudstone shield tunnel slag for 0.5 minutes, then add the composite curing agent and mix for 2 minutes, and finally add cellulose ether and mix for 0.5 minutes to obtain the fluid filling material.

[0076] Example

[0077] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0078] In the following examples, the silty mudstone shield tunneling excavation soil is shield tunneling excavation soil generated during the construction of a subway, wherein the silt content is 55%, the clay content is 45%, and the moisture content is 25%; the recycled micro powder is recycled micro powder generated in the preparation of recycled aggregate from waste concrete, mainly composed of hardened cement stone, unhydrated particles, finely ground sand and stone aggregate. In the comparative example, the completely weathered slate is shield tunneling excavation soil generated during the construction of a subway, wherein the clay content is 96%, the sand and stone content is 4%, and the moisture content is 36%.

[0079] Example 1

[0080] This embodiment provides a fluidized filler material comprising the following components in parts by weight: 80 parts of silty mudstone shield tunnel slag (dry weight), 20 parts of recycled micro powder, 3 parts of granulated blast furnace slag, 10 parts of silicate cement clinker, 1 part of fly ash, 2 parts of phosphogypsum, 0.5 parts of silica fume, 1 part of tung oil, 0.4 parts of hydroxypropyl methylcellulose, 0.1 parts of water-reducing agent (polymethyl methacrylate-methacrylic acid copolymer), 0.7 parts of sodium hexametaphosphate, 0.15 parts of NaOH, and 0.35 parts of Na2SO4.

[0081] The preparation method of this fluidized filling material includes the following steps:

[0082] (1) Crush the muddy siltstone shield tunneling slag to a particle size of no more than 2 mm, and then mix tung oil with the crushed muddy siltstone shield tunneling slag evenly to obtain modified muddy siltstone shield tunneling slag with a moisture content of no less than 30%.

[0083] (2) Grind silicate cement clinker to a specific surface area of ​​not less than 350 m². 2 / kg, to obtain finely ground silicate cement clinker;

[0084] (3) The finely ground silicate cement clinker is mixed evenly with recycled micro powder, granulated blast furnace slag, fly ash, industrial by-product gypsum, silica fume and activator to obtain a composite curing agent;

[0085] (4) First, mix the water-reducing agent, dispersant and modified silty sandstone shield tunnel slag evenly, then add composite curing agent and cellulose ether and stir evenly to obtain the fluid filling material.

[0086] Example 2

[0087] This embodiment provides a fluidized filler material comprising the following components in parts by weight: 95 parts of silty mudstone shield tunnel slag (dry weight), 5 parts of recycled micro powder, 20 parts of granulated blast furnace slag, 1 part of sulfoaluminate cement clinker, 10 parts of fly ash, 0.2 parts of phosphogypsum, 2 parts of silica fume, 6 parts of tung oil, 0.1 parts of hydroxypropyl methylcellulose, 0.7 parts of water-reducing agent (polymethyl methacrylate-methacrylic acid copolymer), 0.1 parts of sodium tripolyphosphate, 0.8 parts of NaOH, and 1.2 parts of Na2SiO3.

[0088] The preparation method of this fluidized filling material includes the following steps:

[0089] (1) Crush the muddy siltstone shield tunneling slag to a particle size of no more than 2 mm, and then mix tung oil with the crushed muddy siltstone shield tunneling slag evenly to obtain modified muddy siltstone shield tunneling slag with a moisture content of no less than 30%.

[0090] (2) Grind the sulfoaluminate cement clinker to a specific surface area of ​​not less than 400 m². 2 / kg, to obtain finely ground sulfoaluminate cement clinker;

[0091] (3) The finely ground sulfoaluminate cement clinker is mixed evenly with recycled micro powder, granulated blast furnace slag, fly ash, industrial by-product gypsum, silica fume and activator to obtain a composite curing agent;

[0092] (4) First, mix the water-reducing agent, dispersant and modified silty sandstone shield tunnel slag evenly, then add composite curing agent and cellulose ether and stir evenly to obtain the fluid filling material.

[0093] Example 3

[0094] This embodiment provides a fluidized bed material comprising the following components by weight: 90 parts of silty mudstone shield tunnel slag (dry weight), 10 parts of recycled micro powder, 5 parts of granulated blast furnace slag, 2 parts of silicate cement clinker, 1 part of fly ash, 0.3 parts of phosphogypsum, 0.5 parts of silica fume, 3 parts of tung oil, 0.15 parts of hydroxypropyl methylcellulose, 0.3 parts of water-reducing agent (polymethyl methacrylate-methacrylic acid copolymer), 0.3 parts of sodium hexametaphosphate, and 0.5 parts of Na2SO4. The preparation method of this fluidized bed material includes the following steps:

[0095] (1) Crush the muddy siltstone shield tunneling slag to a particle size of no more than 2 mm, and then mix tung oil with the crushed muddy siltstone shield tunneling slag evenly to obtain modified muddy siltstone shield tunneling slag with a moisture content of no less than 30%.

[0096] (2) Grind silicate cement clinker to a specific surface area of ​​not less than 350 m². 2 / kg, to obtain finely ground silicate cement clinker;

[0097] (3) The finely ground silicate cement clinker is mixed evenly with recycled micro powder, granulated blast furnace slag, fly ash, industrial by-product gypsum, silica fume and activator to obtain a composite curing agent;

[0098] (4) First, mix the water-reducing agent, dispersant and modified silty sandstone shield tunnel slag evenly, then add composite curing agent and cellulose ether and stir evenly to obtain the fluid filling material.

[0099] Example 4

[0100] This embodiment provides a fluidized filler material comprising the following components in parts by weight: 85 parts of silty mudstone shield tunnel slag (dry weight), 15 parts of recycled micro powder, 9 parts of granulated blast furnace slag, 5 parts of sulfoaluminate cement clinker, 1 part of fly ash, 1.2 parts of desulfurized gypsum, 0.8 parts of silica fume, 5 parts of tung oil, 0.15 parts of methyl cellulose, 0.5 parts of water-reducing agent (polymethyl methacrylate-methyl acrylic acid copolymer), 0.5 parts of sodium hexametaphosphate, 0.4 parts of NaOH, and 1.0 parts of Na2SiO3.

[0101] The preparation method of this fluidized filling material includes the following steps:

[0102] (1) Crush the muddy siltstone shield tunneling slag to a particle size of no more than 2 mm, and then mix tung oil with the crushed muddy siltstone shield tunneling slag evenly to obtain modified muddy siltstone shield tunneling slag with a moisture content of no less than 30%.

[0103] (2) Grind the sulfoaluminate cement clinker to a specific surface area of ​​not less than 400 m². 2 / kg, to obtain finely ground sulfoaluminate cement clinker;

[0104] (3) The finely ground sulfoaluminate cement clinker is mixed evenly with recycled micro powder, granulated blast furnace slag, fly ash, industrial by-product gypsum, silica fume and activator to obtain a composite curing agent;

[0105] (4) First, mix the water-reducing agent, dispersant and modified silty sandstone shield tunnel slag evenly, then add composite curing agent and cellulose ether and stir evenly to obtain the fluid filling material.

[0106] Comparative Example 1

[0107] The only difference between this comparative example and Example 3 is that the muddy siltstone shield tunneling excavation soil is replaced with fully weathered slate shield tunneling excavation soil; all other aspects are the same.

[0108] Comparative Example 2

[0109] The only difference between this comparative example and Example 3 is that no tung oil is added, i.e., the amount of tung oil is 0 parts; everything else is the same.

[0110] Comparative Example 3

[0111] The only difference between this comparative example and Example 3 is that no recycled micro powder is added, that is, the recycled micro powder replaces 0 parts of the silty mudstone shield tunnel slag; all other aspects are the same.

[0112] Comparative Example 4

[0113] The only difference between this comparative example and Example 4 is that the water-reducing agent (polymethyl methacrylate-methacrylic acid copolymer) is replaced with a polycarboxylate high-performance water-reducing agent. The solid content of the two water-reducing agents is the same, and everything else is the same.

[0114] Comparative Example 5

[0115] The only difference between this comparative example and Example 4 is that no cellulose ether is added, i.e., the amount of cellulose ether is 0 parts; everything else is the same.

[0116] The fluidized filling materials prepared in Examples 1-4 and Comparative Examples 1-5 were tested for spread, setting time, bleeding rate, compressive strength, 28-day shrinkage rate, and permeability coefficient. The test methods for spread, compressive strength, and permeability coefficient were conducted according to the "Technical Standard for Premixed Fluidized Solidified Soil Filling" (T / CECS1037-2022); the test methods for setting time and shrinkage rate were conducted according to the "Standard for Basic Performance Test Methods of Building Mortar" (JGJ / T 70-2009); and the test method for bleeding rate was conducted according to the "Technical Specification for Application of Synchronous Grouting Materials in Shield Tunneling" (T / CECS 563-2018). The test results are shown in Table 1.

[0117] Table 1. Test results of Examples 1-2 and Comparative Examples 1-5

[0118]

[0119] As shown in Table 1, by comparing Examples 1-4 with Comparative Examples 1-5, the fluid filling materials prepared in Examples 1-4 have the advantage of high fluidity, as well as the characteristics of short setting time, low bleeding rate, small permeability coefficient and shrinkage rate, and high compressive strength. They can not only improve the backfilling construction efficiency, but also ensure the quality of the filling material.

[0120] The fluid filling material prepared in Example 3 met the relevant requirements of the "Technical Standard for Premixed Fluidized Solidified Soil Filling" (T / CECS1037-2022). In the backfilling of a foundation pit in a certain engineering project, the fluid filling material demonstrated self-leveling and self-compacting properties during construction, along with a short setting time, thus improving construction efficiency and shortening the construction cycle. The hardened solidified soil exhibited a low permeability coefficient, meeting the anti-buoyancy design requirements of building basements, and also showed low shrinkage and no obvious surface cracks. Figure 1 This is the condition of the fluidized filling material prepared in Example 1 before it has fully hardened after backfilling the trough; Figure 2 This is the condition after the fluid filling material prepared in Example 1 has hardened after backfilling the trough.

[0121] The properties of the fluid filling materials prepared in Examples 1, 2 and 4 all meet the relevant requirements of the "Technical Specification for Application of Synchronous Grouting Materials in Shield Tunneling" (T / CECS 563-2018) and can be applied in synchronous grouting projects of shield tunneling.

[0122] A comparison of Example 3 and Comparative Example 1 shows that, due to the higher content of silty mudstone shield tunneling slag compared to completely weathered slate shield tunneling slag, the clay absorbs significantly less water. Furthermore, the silt exhibits a ball-bead effect in the mixture, improving its flowability and thus reducing the water consumption of the slurry, resulting in a significantly lower water-to-cement ratio. Simultaneously, the silt acts as a framework during the hardening process, enhancing the strength of the hardened material and inhibiting its shrinkage. Therefore, while maintaining essentially the same fluidity, Example 3 exhibits a lower water-cement ratio compared to Comparative Example 1, with a significantly shorter setting time, reduced bleeding rate, impermeability coefficient, and shrinkage rate, and a substantial increase in compressive strength.

[0123] A comparison of Example 3 and Comparative Example 2 shows that without the use of tung oil to modify the shield tunneling soil, the water adsorption capacity of the shield tunneling soil is improved. While maintaining a similar level of fluidity, Comparative Example 2 requires a significantly larger amount of mixing water. This indicates that tung oil has a good hydrophobic modification effect on the shield tunneling soil. Tung oil has high polymerization reactivity and can react with Ca(OH)2 to produce calcium carboxylate salts, which can synergistically solidify with gelling substances such as CSH and CAH, resulting in a refined pore structure in the hardened body and thus improving its strength. Tung oil also has good drying and film-forming properties, forming a tung oil film on the surface of clay particles. This film can enhance the bonding force between clay particles and also cut off capillary channels in the hardened body, thereby improving the water permeability resistance of the hardened body.

[0124] A comparison of Example 3 and Comparative Example 3 shows that the addition of recycled micropowder improves both the early and late strength of the fluid filler material of the present invention. The recycled micropowder used in the present invention is generated from the preparation of recycled aggregate from waste concrete, and mainly consists of hardened cement stone, unhydrated particles, finely ground sand and stone aggregate. Ca(OH)2 in the hardened cement stone can react with unhydrated particles to form calcium aluminate and calcium silicate, which become crystal nuclei for cement clinker hydration, thus accelerating the hydration reaction of cement clinker and improving the early strength of the hardened body. The finely ground sand and stone aggregate have a micro-aggregate effect and can form a macro-micro continuous gradation with silt, playing a skeleton role in the hardening of the filler material, which is beneficial to improving the strength of the hardened body.

[0125] A comparison of Example 4 and Comparative Example 4 shows that the water-reducing agent of the present invention is a polymethyl methacrylate-methacrylic acid copolymer, which has a good water-reducing effect on filler materials. Because clay minerals have a layered structure composed of silicon-oxygen tetrahedra and aluminum-oxygen octahedra, the long side chains of polycarboxylate water-reducing agents are easily intercalated and adsorbed between the silicon and aluminum layers, resulting in a relative reduction in the amount of water-reducing agent that can be adsorbed by the cementitious material, thus causing a decrease in the water-reducing rate. However, the side chains of the polymethyl methacrylate-methacrylic acid copolymer are extremely short, which avoids the intercalation and adsorption of side chains between the silicon and aluminum layers of the clay minerals, thereby fully exerting its water-reducing effect. While ensuring the high fluidity of the filler material, it can reduce the amount of mixing water, thereby improving its overall performance.

[0126] A comparison of Example 4 and Comparative Example 5 shows that the addition of cellulose ether is beneficial to improving the cohesiveness of the mixture slurry, thereby reducing segregation and bleeding of the mixture slurry; at the same time, during the coagulation and hardening process of the mixture slurry, it can reduce the evaporation rate of excess water, which is beneficial to reducing cracking of the hardened body.

[0127] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fluidized filling material, characterized in that, The raw material components include the following parts by weight: 80-95 parts of silty mudstone shield tunnel slag (dry weight), 5-20 parts of recycled micro powder, 3-20 parts of granulated blast furnace slag, 1-10 parts of fly ash, 1-10 parts of cement clinker, 0.2-2 parts of industrial by-product gypsum, 0.5-2 parts of silica fume, 1-6 parts of tung oil, 0.1-0.4 parts of cellulose ether, 0.1-0.7 parts of water-reducing agent, 0.1-0.7 parts of dispersant, and 0.5-2 parts of activator. The silty mudstone shield tunneling excavation soil includes silt and clay, with the silt content being no less than 50% by mass; the recycled micro powder is recycled waste concrete micro powder, mainly composed of hardened cement stone, unhydrated particles, and ground sand and stone aggregate; the water-reducing agent is polymethyl methacrylate-methacrylic acid copolymer. The method for preparing the fluidized filling material includes the following steps: The silty mudstone shield tunneling excavation soil is crushed to an average particle size of no more than 2 mm, and then tung oil is mixed evenly with the crushed silty mudstone shield tunneling excavation soil to obtain modified silty mudstone shield tunneling soil. Cement clinker is ground into fine powder to obtain finely ground cement clinker. The finely ground cement clinker is mixed evenly with recycled micro powder, granulated blast furnace slag, fly ash, industrial by-product gypsum, silica fume, and activator to obtain a composite curing agent; First, the water-reducing agent, dispersant and modified silty mudstone shield tunnel slag are mixed together, then the composite curing agent is added and mixed together, and finally the cellulose ether is added and mixed together to obtain the fluid filling material.

2. The fluidized filling material according to claim 1, characterized in that, The raw material components include the following parts by weight: 85-95 parts of muddy siltstone shield tunnel slag (dry weight), 5-15 parts of recycled micro powder, 5-15 parts of granulated blast furnace slag, 1-5 parts of fly ash, 2-8 parts of cement clinker, 0.3-1.5 parts of industrial by-product gypsum, 0.5-1 parts of silica fume, 3-5 parts of tung oil, 0.1-0.2 parts of cellulose ether, 0.1-0.5 parts of water-reducing agent, 0.1-0.5 parts of dispersant, and 0.5-1.5 parts of activator.

3. The fluidized filling material according to claim 1, characterized in that, The residue of the recycled waste concrete powder after sieving through a 45μm square-hole sieve does not exceed 30%.

4. The fluidized filling material according to claim 1, characterized in that, The specific surface area of ​​the granulated blast furnace slag is not less than 400 m². 2 / kg.

5. The fluidized filling material according to claim 1, characterized in that, The fly ash residue after passing through a 45μm square-hole sieve does not exceed 30%; and / or, The specific surface area of ​​the silica fume is not less than 15m². 2 / g.

6. The fluidized filling material according to claim 1, characterized in that, The mineral composition of the industrial by-product gypsum includes CaSO4·2H2O and / or CaSO4; and / or, The industrial by-product gypsum is one or more of the following: desulfurized gypsum, phosphogypsum, fluorogypsum, citric acid gypsum, and titanium gypsum.

7. The fluidized filling material according to claim 1, characterized in that, The tung oil mentioned is natural, refined tung oil.

8. The fluidized filling material according to claim 1, characterized in that, The cellulose ether comprises one or more of methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, and hydroxypropyl methylcellulose; and / or, The dispersant comprises one or more of sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, sodium carbonate, sodium phosphate, and sodium oxalate; and / or, The activator includes one or more of NaOH, Na2SiO3, Na2SO4, and Na2CO3.

9. The fluidized filling material according to claim 1, characterized in that, The cement clinker includes silicate cement clinker, sulfoaluminate cement clinker, or a mixture of silicate cement clinker and sulfoaluminate cement clinker, wherein the silicate cement clinker, after fine grinding, has a specific surface area of ​​not less than 350 m². 2 / kg, the specific surface area of ​​the finely ground sulfoaluminate cement clinker is not less than 400m². 2 / kg; the spread of the fluidized filling material is not less than 1000mm.

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