High-strength impermeable commercial concrete formula and preparation process

Abstract

The application relates to the field of building materials and discloses a high-strength anti-permeation commercial concrete formula and a preparation process; the commercial concrete comprises cement, S95 mineral powder, first-class fly ash, silica fume, fine aggregate, coarse aggregate, water, a polycarboxylic acid water reducing agent, a slow-release polycarboxylic acid slump retaining agent, a calcium sulphoaluminate expansive agent and gradient-liquid-releasing type interface blocking particles. The gradient-liquid-releasing type interface blocking particles comprise porous silicon-aluminum particles, inner active liquid and an outer coating layer; the inner active liquid comprises nano-silica sol, non-chlorine calcium salt and slow-release adjusting agent; and the outer coating layer comprises silica fume, S95 mineral powder, sulphoaluminate clinker fine powder and powder polycarboxylic acid water reducing agent. During preparation, pre-dispersed silica fume paste and a basic paste are formed first, then the gradient-liquid-releasing type interface blocking particles are added and stirred at low speed. The application can improve the transportation stability and the anti-permeation stability after hardening of the commercial concrete.

Description

Technical Field

[0001] This invention relates to the field of building materials, specifically to a high-strength, impermeable commercial concrete formula and preparation process. Background Technology

[0002] Ready-mixed concrete is typically made by mixing cement, mineral admixtures, aggregates, water, and additives in a centralized manner, then transporting it to the construction site by truck and finally pouring it using a pump. For basements, water-retaining structures, bridge abutments, and structures that are exposed to humid environments for extended periods, the concrete must not only meet high compressive strength requirements but also possess stable impermeability.

[0003] Existing high-strength, impermeable ready-mixed concrete often improves density by reducing the water-cement ratio and adding silica fume, mineral powder, fly ash, expanding agents, water-reducing agents, or impermeable agents. Some solutions also utilize porous particles for internal curing or microencapsulated materials to release repair components after cracks form. While these solutions can improve the pore structure of concrete to some extent, most materials directly participate in the slurry dispersion during the mixing stage, making it difficult to balance workability during transportation and continuous sealing during the early hardening stage.

[0004] Especially in low water-cement ratio ready-mixed concrete, silica fume tends to agglomerate, and the paste shows a clear tendency for early water loss and autogenous shrinkage. If the anti-permeability components are released too early, it can easily cause local fluctuations in the water-cement ratio and affect pumping stability. If only later crack repair is relied upon, it is difficult to seal the capillary channels in the early stage of their formation. As a result, the interface transition zone and capillaries are prone to forming continuous permeation paths, leading to insufficient stability of the anti-permeability performance of high-strength concrete. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-strength, impermeable commercial concrete formula and preparation process to solve the technical problems existing in the prior art.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A high-strength, impermeable commercial concrete formula, comprising: The concrete per cubic meter comprises the following components: 300 to 360 kg of cement, 80 to 130 kg of S95 mineral powder, 35 to 70 kg of Grade I fly ash, 20 to 40 kg of silica fume, 650 to 760 kg of fine aggregate, 900 to 1050 kg of coarse aggregate, 130 to 155 kg of water, 8 to 13 kg of polycarboxylate superplasticizer, 1.5 to 4 kg of slump retention component, 15 to 30 kg of expansion agent, and 25 to 60 kg of gradient release interface sealing particles. The gradient-release interface plugging particles include porous aluminosilicate particles, an intrapore active liquid loaded in the pores of the porous aluminosilicate particles, and an outer coating layer covering the outside of the porous aluminosilicate particles. The active liquid within the pores includes nano-silica sol, calcium salts, and a slow-release regulator; The outer coating includes silica fume, S95 mineral powder, fine sulfoaluminate clinker powder, and powdered polycarboxylate superplasticizer; The mass ratio of the outer coating layer to the porous aluminosilicate particles loaded with the porous internal active liquid is 0.08 to 0.20:1; Gradient-release interface-sealing particles are formed by vacuum impregnation to allow active liquid to enter the pores of porous aluminosilicate particles, followed by low-temperature coating with an outer coating layer. The release rate of active liquid in the pores of gradient-release interface plugging particles after soaking in simulated concrete pore liquid with a pH of 12.5 to 13.5 for 2 hours was no higher than 20%, and the release rate of active liquid in the pores after soaking for 24 hours was 55% to 85%.

[0007] Preferably, the fine aggregate accounts for 38% to 43% of the total mass of fine and coarse aggregates, and the gradient release interface sealing particles account for 4% to 12% of the total mass of cementitious materials.

[0008] Preferably, the fine aggregate is medium sand or manufactured sand with a fineness modulus of 2.6 to 3.0, and the coarse aggregate is continuously graded crushed stone with a particle size of 5 to 20 mm, wherein the mass ratio of crushed stone with a particle size of 5 to 10 mm to crushed stone with a particle size of 10 to 20 mm in the continuously graded crushed stone is 1:1.2 to 1:2.5.

[0009] Preferably, the porous aluminosilicate particles are calcined zeolite particles, porous ceramsite fine particles, or recycled brick powder granulated particles. The particle size of the porous aluminosilicate particles is 0.6 to 2.36 mm, the 24-hour water absorption rate is 8% to 18%, and the apparent density is 1200 to 1800 kg / m³. 3 .

[0010] Preferably, the active liquid in the pores comprises, by weight, 80 to 96 parts of nano-silica sol, 3 to 15 parts of non-chlorinated calcium salt, and 0.2 to 2 parts of slow-release regulator. The solid content of the nano-silica sol is 15% to 25%, the non-chlorinated calcium salt is calcium formate or calcium nitrate, and the slow-release regulator is sodium gluconate or sodium citrate. The mass ratio of the active liquid inside the pores to the porous aluminosilicate particles is 0.06 to 0.16:1.

[0011] Preferably, the outer coating layer comprises, by weight, 35 to 55 parts silica fume, 20 to 40 parts S95 mineral powder, 10 to 25 parts sulfoaluminate clinker fine powder, and 1 to 5 parts powdered polycarboxylate superplasticizer, wherein the specific surface area of ​​the sulfoaluminate clinker fine powder is 350 to 550 m². 2 / kg.

[0012] Preferably, the preparation process of the gradient release type interface blocking particles includes: drying porous aluminosilicate particles at 90 to 110°C until the water content is not higher than 1.5%; and placing the dried porous aluminosilicate particles under a vacuum of -0.075 to -0.095 MPa for 10 to 25 minutes. Add the pore-active liquid to the porous aluminosilicate particles and let stand for 15 to 40 minutes; After filtering out the free liquid on the surface of the porous aluminosilicate particles, they are rolled and mixed with the powder raw material of the outer coating layer. Drying at 35 to 55°C allows the outer coating layer to adhere to the outside of porous aluminosilicate particles loaded with pore-containing active liquid, resulting in gradient-release interface-sealing particles.

[0013] A process for preparing high-strength, impermeable commercial concrete includes the following steps: S1: To prepare pre-dispersed silica slurry, silica ash, the first part of water and the first part of polycarboxylate superplasticizer are sheared and dispersed to obtain pre-dispersed silica slurry; S2: Prepare gradient liquid release type interface blocking particles. The active liquid inside the pores is impregnated into the pores of porous aluminosilicate particles through vacuum. The porous aluminosilicate particles loaded with the active liquid inside the pores are then mixed with the powder raw material of the outer coating layer by rolling and drying at 35 to 55°C. S3: Add coarse aggregate, fine aggregate, cement, S95 mineral powder, grade 1 fly ash and calcium sulfoaluminate expansion agent into the mixer and dry mix for 20 to 40 seconds. S4: Add the second part of water and the second part of polycarboxylate superplasticizer, and stir for 50 to 90 seconds. The second part of water is 70% to 85% of the remaining water after deducting the first part of water. S5: Add pre-dispersed silica slurry, remaining water and remaining polycarboxylate superplasticizer, and stir for 40 to 70 seconds; S6: Add gradient release interface blocking particles and stir at a speed of 20 to 45 r / min for 40 to 90 s; S7: After adding the slow-release polycarboxylate slump retainer, stir for 30 to 60 seconds to obtain high-strength impermeable commercial concrete.

[0014] Preferably, when preparing the pre-dispersed silica fume slurry, the mass ratio of silica fume to the first part of water is 1:0.8 to 1:1.5, the first part of polycarboxylate superplasticizer accounts for 15% to 35% of the total mass of polycarboxylate superplasticizer, the shearing speed is 1200 to 2500 r / min, and the shearing time is 3 to 8 min.

[0015] Preferably, when preparing gradient liquid-releasing interface sealing particles, porous aluminosilicate particles loaded with pore-active liquid are mixed with powder raw materials of the outer coating layer in a drum device, the rotation speed of the drum device is 15 to 40 r / min, and the mixing time is 5 to 15 min.

[0016] In summary, the present invention has the following main beneficial effects: Compared with existing technologies, this application sets gradient-release interface-sealing particles in a low water-cement ratio cementitious system. These particles are composed of porous aluminosilicate particles, an active liquid within the pores, and an outer coating layer. This allows the nano-silica sol, non-chlorinated calcium salt, and slow-release regulator to be loaded into the pores of the porous aluminosilicate particles rather than directly dispersed in the concrete mixing water. The release is then delayed by the outer coating layer formed by silica fume, S95 mineral powder, sulfoaluminate clinker fine powder, and powdered polycarboxylate superplasticizer. This avoids the concentrated release of the active liquid within the pores during the initial mixing stage, which would cause local fluctuations in the water-cement ratio. As a result, the system maintains stability during the transportation and pumping of ready-mixed concrete.

[0017] This application limits the release rates of calcium salts within the pores of gradient-release interface-sealing particles in simulated concrete pore fluid over 2 hours and 24 hours, making the release process of these particles correspond to the stages of ready-mixed concrete from mixing and transportation to the early hardening stage. During the mixing and transportation stages, the outer coating layer delays the escape of components from the pores. In the early hardening stage, the active liquid within the pores is gradually released as the pore fluid wets the particles. Nano-silica sol, non-chlorinated calcium salts, and related components in the cement hydration environment undergo subsequent reactions, and together with silica fume, mineral powder, and sulfoaluminate clinker fine powder, form a filling structure around the particles, thereby reducing the interfacial transition zone and the continuity of capillary channels, thus improving the impermeability stability of the concrete.

[0018] This application employs a preparation sequence of first preparing pre-dispersed silica fume slurry, then forming a base slurry, followed by the addition of gradient-release interface-sealing particles and low-speed stirring. This allows the silica fume to disperse in a low water-cement ratio system first, preventing agglomeration caused by direct dry addition, and simultaneously preventing premature damage to the outer coating layer by the gradient-release interface-sealing particles during the high-shear stage. This process achieves a continuous balance between silica fume dispersion, particle coating layer maintenance, and uniform particle distribution, thus balancing the workability, hardened strength, and impermeability of ready-mixed concrete. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 refer to Figure 1 A high-strength, impermeable commercial concrete formula, comprising: This product is suitable for applications where ready-mixed concrete is centrally mixed at a plant, transported to the construction site, and then pumped for pouring. The commercial concrete is based on a silicate cement system, forming a low water-to-binder ratio cementitious system through cement, S95 mineral powder, grade I fly ash, silica fume, and calcium sulfoaluminate-based expanding agents. Gradient-release interface-sealing particles are added to this cementitious system. These gradient-release interface-sealing particles are not ordinary water-absorbing particles, nor are they crack-triggering microcapsules. Instead, they are composite particles formed by porous aluminosilicate particles, an intrapore active liquid loaded within the pores of the porous aluminosilicate particles, and an outer coating layer covering the outside of the porous aluminosilicate particles.

[0022] In this embodiment, the ready-mixed concrete, per cubic meter, comprises the following components: 300 to 360 kg of cement, 80 to 130 kg of S95 mineral powder, 35 to 70 kg of Grade I fly ash, 20 to 40 kg of silica fume, 650 to 760 kg of fine aggregate, 900 to 1050 kg of coarse aggregate, 130 to 155 kg of water, 8 to 13 kg of polycarboxylate superplasticizer, 1.5 to 4 kg of slow-release polycarboxylate slump retainer, 15 to 30 kg of calcium sulfoaluminate expansive agent, and 25 to 60 kg of gradient-release interface sealing particles.

[0023] In this embodiment, cement, S95 mineral powder, grade I fly ash, silica fume, and calcium sulfoaluminate-based expanding agents together constitute the cementitious material, with a water-to-cement ratio of 0.26 to 0.32. The water referred to here is the added mixing water during the concrete mixing stage, excluding the water dispersion medium carried by the nano-silica sol itself, and also excluding the active liquid within the pores of the porous aluminosilicate particles. The active liquid within the pores is included in the mass of the gradient-release interface-sealing particles as an internal loading component, but is not included in the water-cement ratio as added mixing water. Therefore, the water-cement ratio is calculated as the ratio of the mass of added mixing water to the total mass of the cementitious material, avoiding double-counting of the liquid medium carried by the nano-silica sol and the mixing water.

[0024] Ordinary Portland cement can be used. The specific surface area of ​​S95 mineral powder is 400 to 480 m². 2 / kg. The water requirement of Grade I fly ash shall not exceed 95%. The silica content in silica fume shall not be less than 90% by mass. Calcium sulfoaluminate-based expanding agents shall be used as part of the cementitious materials in the proportioning calculation and shall not be deducted separately from the total amount of cementitious materials.

[0025] Fine aggregate consists of medium sand or manufactured sand with a fineness modulus of 2.6 to 3.0. Coarse aggregate consists of continuously graded crushed stone with a particle size of 5 to 20 mm. In continuously graded crushed stone, the mass ratio of crushed stone with a particle size of 5 to 10 mm to crushed stone with a particle size of 10 to 20 mm is 1:1.2 to 1:2.5. The mass percentage of fine aggregate in the total mass of fine and coarse aggregate is 38% to 43%. When the proportion of fine aggregate is less than 38%, the continuity of the low water-cement ratio paste's coating on the aggregate is insufficient; when the proportion of fine aggregate is greater than 43%, the water demand of the system increases, which can easily weaken the stability of the low water-cement ratio design.

[0026] In one specific mix proportion, each cubic meter of ready-mixed concrete includes 330 kg of cement, 110 kg of S95 mineral powder, 50 kg of Grade I fly ash, 30 kg of silica fume, 700 kg of fine aggregate, 980 kg of coarse aggregate, 145 kg of water, 10 kg of polycarboxylate superplasticizer, 2.5 kg of slow-release polycarboxylate slump retainer, 20 kg of calcium sulfoaluminate expansive agent, and 40 kg of gradient-release interface sealing particles. In this specific mix proportion, the total amount of cementitious materials is 540 kg, the water-cement ratio is 0.268, the mass percentage of fine aggregate in the total mass of fine and coarse aggregate is 41.7%, and the mass percentage of gradient-release interface sealing particles in the total mass of cementitious materials is 7.4%, all of which fall within the scope defined in this application.

[0027] In this embodiment, the gradient-release interface sealing particles comprise porous aluminosilicate particles, an intrapore active liquid loaded within the pores of the porous aluminosilicate particles, and an outer coating layer covering the outside of the porous aluminosilicate particles. The porous aluminosilicate particles are calcined zeolite particles, fine porous ceramsite particles, or granulated particles from recycled brick powder. The particle size of the porous aluminosilicate particles is 0.6 to 2.36 mm, the 24-hour water absorption rate is 8% to 18%, and the apparent density is 1200 to 1800 kg / m³. 3 .

[0028] The particle size of the porous aluminosilicate particles was determined by sieving. Particles that could pass through a 2.36 mm sieve but could not completely pass through a 0.6 mm sieve were considered to meet the particle size requirements. The apparent density of the porous aluminosilicate particles was calculated by dividing the dry mass of the particles by the volume of water displaced by the particles. Before measurement, there should be no free water on the surface of the particles.

[0029] The 24-hour water absorption rate of porous aluminosilicate particles was determined as follows: the porous aluminosilicate particles were dried at 105±5°C to constant weight, and the dried mass was measured. Soak the particles in water at 20±2°C for 24 hours. After removing them, wipe off the excess water on the surface of the particles with a damp cloth and weigh them to determine their surface dryness. 24-hour water absorption rate Calculate using the following formula:

[0030] in, To actively reject drift weights, To proactively reject drifting, the initial weight is set as follows: M represents the number of times push events were turned off, N represents the number of times events were ignored, and T represents the push event unsubscription flag. , , This is the rejection weight coefficient generated by the e-commerce platform server based on historical push feedback logs. T is set to 1 when a target user unsubscribes from push notifications; otherwise, T is set to 0. The number of push notification events closed (M) and the number of events ignored (N) are both calculated based on push notifications for the same product category within the current session window and the 24 hours preceding the start of the current session window.

[0031] The in-pore active liquid comprises, by weight, 80 to 96 parts of nano-silica sol, 3 to 15 parts of non-chlorinated calcium salt, and 0.2 to 2 parts of a slow-release regulator. The solid content of the nano-silica sol is 15% to 25%. The non-chlorinated calcium salt is calcium formate or calcium nitrate. The slow-release regulator is sodium gluconate or sodium citrate. The mass ratio of the in-pore active liquid to the porous aluminosilicate particles is 0.06 to 0.16:1.

[0032] In one specific embodiment, the pore-active liquid is prepared by mixing 90 parts by weight of nano-silica sol, 8 parts by weight of calcium formate, and 1 part by weight of sodium gluconate, wherein the solid content of the nano-silica sol is 20%. To prepare the pore-active liquid, calcium formate and sodium gluconate are first added to the nano-silica sol and stirred until the system is homogeneous to obtain the pore-active liquid. If calcium nitrate is used instead of calcium formate, it is added within the same weight range. When calcium nitrate exists in different hydration states, the calcium element mass fraction in the calculation of the pore-active calcium salt release rate is determined according to the hydration state and purity of the calcium nitrate product used. The calcium element mass fraction in the calculation of the non-chlorinated calcium salt release rate is based on the nominal calcium content or measured calcium content of the same batch of non-chlorinated calcium salts.

[0033] The outer coating, by weight, comprises 35 to 55 parts silica fume, 20 to 40 parts S95 mineral powder, 10 to 25 parts sulfoaluminate clinker fine powder, and 1 to 5 parts powdered polycarboxylate superplasticizer. The specific surface area of ​​the sulfoaluminate clinker fine powder is 350 to 550 m². 2 / kg. The mass ratio of the outer coating layer to the porous aluminosilicate particles loaded with the porous internal active liquid is 0.08 to 0.20:1.

[0034] In one specific embodiment, the outer coating layer is formed by mixing 45 parts by weight of silica fume, 30 parts of S95 mineral powder, 20 parts of fine sulfoaluminate clinker powder, and 3 parts of powdered polycarboxylate superplasticizer. The above-mentioned powder raw materials are pre-dry mixed for 3 to 5 minutes to ensure uniform dispersion before being used to coat porous aluminosilicate particles loaded with the active liquid within the pores. The outer coating layer is a powder layer on the outer side of the particles formed by powder adhesion and low-temperature drying; it is not required to form a continuous, non-porous sealing film layer, nor is it used as the microcapsule wall. The outer coating layer is used to delay the release of the active liquid within the pores during the initial mixing stage, but it is not intended to completely block the contact between the active liquid within the pores and the external pore liquid.

[0035] The preparation process of gradient release type interface blocking particles is as follows.

[0036] The porous aluminosilicate particles are first dried at 90 to 110°C until the moisture content is no higher than 1.5%. The moisture content is the dry basis moisture content, calculated based on the mass difference before and after drying, using the following formula:

[0037] In the formula, M is the dry basis moisture content of the porous aluminosilicate particles, in %; m_a is the mass of the porous aluminosilicate particles before drying, in g; and m° is the mass of the porous aluminosilicate particles after drying.

[0038] The dried porous aluminosilicate particles were placed in a vacuum container and maintained under a vacuum of -0.075 to -0.095 MPa for 10 to 25 minutes to expel some of the air from the pores. Then, an active liquid was added to the vacuum container, covering the particles. After releasing the vacuum, the particles were allowed to stand for 15 to 40 minutes to allow the active liquid to penetrate the pores. After standing, the free liquid on the surface of the particles was filtered off, yielding porous aluminosilicate particles loaded with the active liquid. The loading of the active liquid was determined by the mass difference of the porous aluminosilicate particles before and after impregnation; the final mass was the mass after removing the free liquid from the surface.

[0039] Porous aluminosilicate particles loaded with an internally active liquid are tumble-mixed with an outer coating of powder raw material. The tumbling mixing is carried out inside a drum mixer at a speed of 15 to 40 rpm for 5 to 15 minutes. During mixing, the wetted layer on the surface of the loaded particles acts as a powder adhesion medium, allowing silica fume, S95 mineral powder, sulfoaluminate clinker fine powder, and powder polycarboxylate superplasticizer to adhere to the outer side of the particles. After tumbling mixing, the particles are dried at 35 to 55°C, allowing the outer coating to adhere to the outer side of the porous aluminosilicate particles loaded with the internally active liquid, resulting in gradient-release interface-sealing particles. This drying step ends with no free liquid on the particle surface and the particles able to flow freely, not with the aim of removing the internally active liquid.

[0040] To clarify the release performance of gradient-release interface-blocking particles, this embodiment uses the intrapore calcium salt release rate to characterize the particle release behavior. The simulated concrete pore fluid was prepared from a saturated calcium hydroxide solution and a sodium hydroxide solution. The preparation method was as follows: a saturated calcium hydroxide solution was prepared at 20±2℃, allowed to stand, and then filtered to obtain a clear liquid; sodium hydroxide solution was added to the clear liquid to adjust the pH to 12.5 to 13.5. The pH value was measured using a calibrated pH meter. The blank simulated concrete pore fluid and the simulated concrete pore fluid used in the immersion test were prepared from the same batch.

[0041] When detecting the calcium salt release rate within the pores, gradient-release interface sealing particles with no free water on their surface and in a loose state were used as the test sample. The test sample was not crushed. The test sample was added to the simulated concrete pore fluid at a mass-to-volume ratio of 1g:20mL, and then allowed to stand and soak at 20±2℃. The soaking time was calculated from the moment the test sample was completely immersed in the simulated concrete pore fluid. After soaking for 2 hours or 24 hours, the solution was filtered, and the calcium ion concentration was measured. The calcium ion concentration could be detected using ethylenediaminetetraacetic acid titration or inductively coupled plasma atomic emission spectrometry. The same detection method was used for both the 2-hour and 24-hour release rates in the same embodiment.

[0042] The calcium salt release rate within the pores is calculated using the following formula:

[0043] In the formula, The soaking time is Calcium salt release rate within the pores at that time; The soaking time is The mass concentration of calcium ions in the soaking solution; This serves as a blank to simulate the calcium ion mass concentration in the pore fluid of concrete. This refers to the volume of the soaking liquid; The mass of non-chlorinated calcium salt loaded in the gradient release interface blocking particles to be tested; The mass fraction of calcium in the non-chlorinated calcium salt; The soaking time is 2 hours or 24 hours.

[0044] in, The calculation was based on the weight gain of the same batch of particles before and after impregnation, and the mass fraction of non-chlorinated calcium salts in the active solution within the pores. If the non-chlorinated calcium salt is calcium formate, then... The determination is based on the mass fraction of calcium in calcium formate; if the non-chlorinated calcium salt is calcium nitrate, then... The determination should be based on the hydration state and purity of the calcium nitrate product used. The test results should meet the following requirements: the calcium salt release rate of the gradient release interface sealing particles after soaking in simulated concrete pore fluid for 2 hours should not exceed 20%, and the calcium salt release rate after soaking for 24 hours should be 55% to 85%.

[0045] The above release rate range applies to the transportation stage and early hardening stage of ready-mixed concrete. A 2-hour release rate of no more than 20% indicates that the particles do not release a large amount of material during the initial mixing and transportation stages; a 24-hour release rate of 55% to 85% indicates that the particles can release pore components during the early hardening stage. This release rate range is not simply a material performance indicator, but is determined by a combination of factors including the pore loading capacity of the porous aluminosilicate particles, the mass ratio of the outer coating, the wetting state of the outer coating, and the low-speed post-construction process.

[0046] This application also provides the preparation process of the above-mentioned high-strength impermeable commercial concrete.

[0047] The first step is to prepare pre-dispersed silica fume slurry. Silica fume, water (part 1), and polycarboxylate superplasticizer (part 1) are sheared and dispersed to obtain pre-dispersed silica fume slurry. The mass ratio of silica fume to water (part 1) is 1:0.8 to 1:1.5. The polycarboxylate superplasticizer (part 1) accounts for 15% to 35% of the total mass of polycarboxylate superplasticizer. The shearing speed is 1200 to 2500 r / min, and the shearing time is 3 to 8 min. The water (part 1) is included in the total admixture water per cubic meter of concrete, and the polycarboxylate superplasticizer (part 1) is included in the total polycarboxylate superplasticizer content per cubic meter of concrete.

[0048] The second step is to prepare gradient-release interface sealing particles. This is carried out following the steps described above: drying porous aluminosilicate particles, vacuum impregnation, filtering out free liquid, rolling coating, and drying at 35 to 55°C. The resulting gradient-release interface sealing particles should have a surface free of free liquid and be in a loose state to avoid particle agglomeration during subsequent concrete mixing.

[0049] The third step involves adding coarse aggregate, fine aggregate, cement, S95 mineral powder, grade 1 fly ash, and calcium sulfoaluminate-based expanding agent into a mixer and dry-mixing for 20 to 40 seconds. This step allows the cementitious material powder to initially disperse and adhere to the aggregate surface, reducing the formation of clumps after subsequent water addition.

[0050] The fourth step involves adding the second portion of water and the second portion of polycarboxylate superplasticizer, and stirring for 50 to 90 seconds to form the basic slurry. The second portion of water comprises 70% to 85% of the remaining water after deducting the first portion. This second portion of water is not 70% to 85% of the total added mixing water, but rather 70% to 85% of the remaining water after deducting the first portion used for the pre-dispersed silica slurry, to avoid duplicate metering of the water used in the pre-dispersed silica slurry and subsequent water additions. The second portion of polycarboxylate superplasticizer is a portion of the polycarboxylate superplasticizer remaining after deducting the first portion.

[0051] Step 5: Add the pre-dispersed silica slurry, remaining water, and remaining polycarboxylate superplasticizer, and stir for 40 to 70 seconds. The remaining water is the water remaining after deducting the first and second portions of water, and the remaining polycarboxylate superplasticizer is the polycarboxylate superplasticizer remaining after deducting the first and second portions. This step allows the pre-dispersed silica slurry to enter the base slurry and, together with cement, S95 mineral powder, grade I fly ash, and calcium sulfoaluminate expansive agent, form a low water-to-binder ratio cementitious system.

[0052] Step 6: Add the gradient-release interface sealing particles and stir at a speed of 20 to 45 rpm for 40 to 90 seconds. This stirring speed is lower than the stirring speed during the formation of the base slurry. Adding the gradient-release interface sealing particles after the pre-dispersed silica slurry is to prevent excessive damage to the outer coating layer of the particles during the high-shear stage. Low-speed stirring is used to disperse the gradient-release interface sealing particles in the concrete while maintaining the bonding between the outer coating layer and the particle core.

[0053] Step 7: After adding the slow-release polycarboxylate slump retainer, stir for 30 to 60 seconds to obtain high-strength, impermeable ready-mixed concrete. The slow-release polycarboxylate slump retainer is added at this stage to meet the transportation and construction needs of the low water-cement ratio system. The slow-release polycarboxylate slump retainer is not included in the dosage range of the polycarboxylate superplasticizer; the two are measured separately as different admixtures.

[0054] The parameter ranges in this application are determined based on the mix design logic of high-strength commercial concrete, particle load-bearing capacity, outer coating layer formation state, and release rate test results. A water-cement ratio of 0.26 to 0.32 is used to balance the strength requirements of the cementitious system and the pumpability of C60 to C80 grade commercial concrete. The porous aluminosilicate particles have a particle size of 0.6 to 2.36 mm, placing them between fine aggregate particles and mineral admixtures, avoiding insufficient loading of the active liquid within the pores due to excessively fine particles, and also avoiding localized weak interfaces caused by excessively coarse particles. The mass ratio of the outer coating layer to the porous aluminosilicate particles loaded with the active liquid within the pores is 0.08 to 0.20:1, used to form a wettable outer powder layer. The pore calcium salt release rate ranges at 2 h and 24 h are used to distinguish between the mixing and transportation stage and the early hardening stage.

[0055] The gradient-release interface-sealing particles in this application differ from ordinary hydrophilic microporous sintered particles. Ordinary hydrophilic microporous sintered particles typically use nano-silica as one of the particle raw materials during sintering, subsequently absorbing water through the particle pores. In this application, nano-silica sol is not used as a sintering raw material, nor is it directly added to the concrete paste as a liquid admixture. Instead, it is co-loaded within the pores of porous aluminosilicate particles with non-chloride calcium salts and slow-release regulators. The outer coating layer is not a single silica protective layer, but a wettable powder layer composed of silica fume, S95 mineral powder, fine sulfoaluminate clinker powder, and powdered polycarboxylate superplasticizer.

[0056] The gradient-release interface-sealing particles in this application differ from ordinary porous internal curing admixtures. Ordinary porous internal curing admixtures mainly rely on particle water absorption and release to regulate internal humidity. The particles in this application not only have an internal liquid load, but also specify the nano-silica sol, non-chlorinated calcium salt, and slow-release regulator in the active liquid within the pores, and specify the composition of the outer coating layer, the mass ratio of the outer coating layer, the calcium salt release rate within the pores, and the order of subsequent low-speed mixing. Therefore, its technical features are not equivalent to adding porous materials as ordinary internal curing admixtures to concrete.

[0057] The gradient-release interface-sealing particles in this application differ from crack-triggered self-healing microcapsules. Crack-triggered self-healing microcapsules typically rely on crack propagation to destroy the capsule wall before releasing the repair agent. In this application, the outer coating layer does not seal the capsule wall, and the particle release behavior does not depend on crack destruction triggering. Instead, it gradually releases intrapore calcium salts under simulated concrete pore fluid conditions according to release rates ranging from 2h to 24h. This release boundary is jointly determined by the porous aluminosilicate particles, the intrapore active liquid, the outer coating layer, and the low-rate post-addition process.

[0058] To illustrate the synergistic relationship between the various structures, comparative samples can be set up for verification. Comparative sample one does not contain gradient-release interface-sealing particles. Comparative sample two contains porous aluminosilicate particles that are not loaded with intrapore active liquid and do not form an outer coating layer. Comparative sample three contains porous aluminosilicate particles loaded with intrapore active liquid but do not form an outer coating layer. The example sample contains the gradient-release interface-sealing particles of this application. Except for the differences in the corresponding particles, the amounts of cement, S95 mineral powder, grade I fly ash, silica fume, aggregate, water, polycarboxylate superplasticizer, slow-release polycarboxylate slump retainer, and calcium sulfoaluminate expansive agent are kept consistent for all the above samples. Through this comparison method, the influence of simply adding porous particles, simply loading intrapore active liquid, or simply increasing mineral powder on performance can be eliminated, thereby verifying the correlation between intrapore active liquid, outer coating layer, and post-injection low-speed stirring.

[0059] In practice, the slump at the machine, slump retention during transport time, 28-day compressive strength, 56-day compressive strength, impermeability grade, chloride ion flux, autogenous shrinkage, and pore morphology of the interface transition zone after hardening can be tested on the above-mentioned samples. The test results can be used to evaluate the influence of different particle structures on the workability, strength, and impermeability of ready-mixed concrete. If it is necessary to observe the microstructure, the interface transition zone around the coarse aggregate in the hardened concrete sample can be selected, and the sample can be observed using a scanning electron microscope. Alternatively, a pore size distribution test method can be used to observe capillary changes. The above tests are for effect verification purposes and do not affect those skilled in the art from preparing the ready-mixed concrete of this application according to the aforementioned formula and process.

[0060] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-strength, impermeable commercial concrete formula, characterized in that, The concrete per cubic meter comprises the following components: 300 to 360 kg of cement, 80 to 130 kg of S95 mineral powder, 35 to 70 kg of Grade I fly ash, 20 to 40 kg of silica fume, 650 to 760 kg of fine aggregate, 900 to 1050 kg of coarse aggregate, 130 to 155 kg of water, 8 to 13 kg of polycarboxylate superplasticizer, 1.5 to 4 kg of slump retention component, 15 to 30 kg of expansion agent, and 25 to 60 kg of gradient release interface sealing particles. The gradient-release interface plugging particles include porous aluminosilicate particles, an intrapore active liquid loaded in the pores of the porous aluminosilicate particles, and an outer coating layer covering the outside of the porous aluminosilicate particles. The active liquid within the pores includes nano-silica sol, calcium salts, and a slow-release regulator; The outer coating includes silica fume, S95 mineral powder, fine sulfoaluminate clinker powder, and powdered polycarboxylate superplasticizer; The mass ratio of the outer coating layer to the porous aluminosilicate particles loaded with the porous internal active liquid is 0.08 to 0.20:1; Gradient-release interface-sealing particles are formed by vacuum impregnation to allow active liquid to enter the pores of porous aluminosilicate particles, followed by low-temperature coating with an outer coating layer. The release rate of active liquid in the pores of gradient-release interface plugging particles after soaking in simulated concrete pore liquid with a pH of 12.5 to 13.5 for 2 hours was no higher than 20%, and the release rate of active liquid in the pores after soaking for 24 hours was 55% to 85%.

2. The high-strength, impermeable commercial concrete formula according to claim 1, characterized in that, The fine aggregate accounts for 38% to 43% of the total mass of fine and coarse aggregates, and the gradient release interface sealing particles account for 4% to 12% of the total mass of cementitious materials.

3. The high-strength, impermeable commercial concrete formula according to claim 2, characterized in that, The fine aggregate is medium sand or manufactured sand with a fineness modulus of 2.6 to 3.0, and the coarse aggregate is continuously graded crushed stone with a particle size of 5 to 20 mm. The mass ratio of crushed stone with a particle size of 5 to 10 mm to crushed stone with a particle size of 10 to 20 mm in the continuously graded crushed stone is 1:1.2 to 1:2.

5.

4. The high-strength, impermeable commercial concrete formula according to claim 3, characterized in that, The porous aluminosilicate particles are calcined zeolite particles, porous ceramsite fine particles, or recycled brick powder granulated particles. The particle size of the porous aluminosilicate particles is 0.6 to 2.36 mm, the 24-hour water absorption rate is 8% to 18%, and the apparent density is 1200 to 1800 kg / m³. 3 .

5. The high-strength, impermeable commercial concrete formula according to claim 4, characterized in that, The active liquid in the pores comprises, by weight, 80 to 96 parts of nano-silica sol, 3 to 15 parts of non-chlorinated calcium salt, and 0.2 to 2 parts of slow-release regulator. The solid content of the nano-silica sol is 15% to 25%, the non-chlorinated calcium salt is calcium formate or calcium nitrate, and the slow-release regulator is sodium gluconate or sodium citrate. The mass ratio of the active liquid inside the pores to the porous aluminosilicate particles is 0.06 to 0.16:

1.

6. The high-strength, impermeable commercial concrete formula according to claim 5, characterized in that, The outer coating layer comprises, by weight, 35 to 55 parts silica fume, 20 to 40 parts S95 mineral powder, 10 to 25 parts sulfoaluminate clinker fine powder, and 1 to 5 parts powdered polycarboxylate superplasticizer. The specific surface area of ​​the sulfoaluminate clinker fine powder is 350 to 550 m². 2 / kg.

7. The high-strength, impermeable commercial concrete formula according to claim 6, characterized in that, The preparation process of the gradient release type interface blocking particles includes: drying porous aluminosilicate particles at 90 to 110°C until the water content is not higher than 1.5%; and placing the dried porous aluminosilicate particles under a vacuum of -0.075 to -0.095 MPa for 10 to 25 minutes. Add the pore-active liquid into the porous aluminosilicate particles and let it stand for 15 to 40 minutes; After filtering out the free liquid on the surface of the porous aluminosilicate particles, they are rolled and mixed with the powder raw material of the outer coating layer. Drying at 35 to 55°C allows the outer coating layer to adhere to the outside of porous aluminosilicate particles loaded with pore-containing active liquid, resulting in gradient-release interface-sealing particles.

8. A preparation process for high-strength impermeable commercial concrete, applicable to the high-strength impermeable commercial concrete formula according to any one of claims 1-7, characterized in that, Includes the following steps: S1: To prepare pre-dispersed silica slurry, silica ash, the first part of water and the first part of polycarboxylate superplasticizer are sheared and dispersed to obtain pre-dispersed silica slurry; S2: Prepare gradient liquid release type interface blocking particles. The active liquid inside the pores is impregnated into the pores of porous aluminosilicate particles through vacuum. The porous aluminosilicate particles loaded with the active liquid inside the pores are then mixed with the powder raw material of the outer coating layer by rolling and drying at 35 to 55°C. S3: Add coarse aggregate, fine aggregate, cement, S95 mineral powder, grade 1 fly ash and calcium sulfoaluminate expansion agent into the mixer and dry mix for 20 to 40 seconds. S4: Add the second part of water and the second part of polycarboxylate superplasticizer, and stir for 50 to 90 seconds. The second part of water is 70% to 85% of the remaining water after deducting the first part of water. S5: Add pre-dispersed silica slurry, remaining water and remaining polycarboxylate superplasticizer, and stir for 40 to 70 seconds; S6: Add gradient release interface blocking particles and stir at a speed of 20 to 45 r / min for 40 to 90 s; S7: After adding the slow-release polycarboxylate slump retainer, stir for 30 to 60 seconds to obtain high-strength impermeable commercial concrete.

9. The preparation process of high-strength impermeable commercial concrete according to claim 8, characterized in that, When preparing pre-dispersed silica fume slurry, the mass ratio of silica fume to water in the first part is 1:0.8 to 1:1.5, the first part of polycarboxylate superplasticizer accounts for 15% to 35% of the total mass of polycarboxylate superplasticizer, the shearing speed is 1200 to 2500 r / min, and the shearing time is 3 to 8 min.

10. The preparation process of high-strength impermeable commercial concrete according to claim 9, characterized in that, When preparing gradient liquid-releasing interface plugging particles, porous aluminosilicate particles loaded with pore-active liquid are mixed with powder raw materials with outer coating in a drum equipment. The rotation speed of the drum equipment is 15 to 40 r / min, and the mixing time is 5 to 15 min.

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