High impermeability structure self-waterproofing concrete and preparation method thereof

Abstract

The application discloses a kind of high anti-permeability structure self-waterproof concrete and preparation method thereof, it is related to concrete technical field, including, the particle size composition of coarse aggregate is obtained, surface density and particle shape data, the effective surface area of the coarse aggregate is determined, the sum of cement, fly ash and cement-based permeable crystalline waterproof agent mass required by concrete mix proportion is defined as total cementitious material mass, according to the target water-powder ratio of interface reaction slurry, first stage water is mixed with the interface powder, interface reaction slurry is prepared, under the condition that no fine aggregate is added, the interface reaction slurry is mixed with all coarse aggregate, so that the interface reaction slurry coats the outer surface of the coarse aggregate, the concrete preparation method of the application utilizes coarse aggregate effective surface area to determine the dosage of interface powder and interface waterproof agent, so that the unit area dosage under different particle size composition and particle shape conditions is comparable, and through upper and lower limit of proportion, avoid abnormal grading to cause too little or too much.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, and in particular to a high-permeability self-waterproof concrete and its preparation method. Background Technology

[0002] The coarse aggregate-cement paste interface transition zone in concrete typically features a high local water-cement ratio, numerous pores, and oriented enrichment of calcium hydroxide, making it a continuous channel for the migration of water and corrosive media. Using a staged mixing method that pre-coats aggregates with neat cement paste or admixtures allows for the formation of a paste film on the aggregate surface before conventional mixing, thereby adjusting the composition and nucleation conditions of the interface zone.

[0003] For example, CN1031962A / CN1004540B, "Process for Coating Aggregate Concrete with Neat Paste," discloses a process of first preparing a neat paste with a water-cement ratio of 0.25 to 0.4, then mixing it with aggregate and adding the remaining water; CN1994709A / CN100556640C, "A Method for Preparing Aggregate Concrete with Admixtures," discloses a process of first pre-absorbing water into the aggregate, then coating the aggregate with slag, silica fume, fly ash, or calcined kaolin; CN112876169A / CN112876169B, "A Paste Composition, Paste-Coated Aggregate, and Preparation Method Thereof," discloses a paste containing calcined clay, limestone, gypsum, and cement, and its coating of aggregate. The above scheme demonstrates that adjusting the feeding sequence and the slurry film on the aggregate surface can improve the interface zone, but it does not establish a linkage relationship between the amount of waterproof active material and the amount of water used in the first stage, taking into account the effective surface area of ​​different batches of coarse aggregate and the actual water absorption behavior in the coating stage.

[0004] Two-stage mixing studies further demonstrate that the coarse aggregate coating method is one of the two-stage mixing pathways that can be used to improve the homogeneity of conventional concrete. Related studies categorize two-stage mixing into types such as pre-mixing mortar, coarse aggregate coating with mortar, and aggregate coating with cement, noting that the suitable pathway varies depending on the concrete system. Other studies have added silica fume and some cement during the premixing stage of recycled aggregate to fill weak areas on the aggregate surface and form a denser interface layer. These studies mainly compare the order of addition or premixed components, without providing quantitative control methods applicable to fluctuations in aggregate gradation, particle shape, and moisture content. Summary of the Invention

[0005] In view of the above problems, the present invention proposes the following technical solution.

[0006] Therefore, this invention provides a method for preparing high impermeability self-waterproof concrete to solve the problem that different coarse aggregate gradations and particle shapes lead to different interfacial material amounts per unit surface area for the same fixed material proportion, and that the water absorption of coarse aggregate during the short-term coating stage changes the actual water-powder ratio of the interfacial slurry.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing highly impermeable, self-waterproof concrete, comprising: obtaining data on the particle size distribution, surface density, and particle shape of coarse aggregate; and determining the effective surface area of ​​the coarse aggregate. The coating water absorption rate of coarse aggregates from the same material source is determined according to the predetermined coating time. The coating water absorption rate For coarse aggregate, the water-to-powder ratio is reduced to the target water-to-powder ratio within the predetermined coating time. Furthermore, the ratio of water absorbed by the reference cement slurry without waterproofing agent to the dry weight of coarse aggregate;

[0009] The total mass of cementitious materials is defined as the sum of the masses of cement, fly ash, and cement-based penetrating crystalline waterproofing agent required for the concrete mix design. According to the effective surface area Determine the quality of the interface waterproofing agent separately and interface powder quality The same type of cement-based penetrating crystalline waterproofing agent is divided into interface waterproofing agent and matrix waterproofing agent. Interface cement and interface fly ash are separated from cement and fly ash, and the interface powder is composed of the interface cement, interface fly ash and interface waterproofing agent.

[0010] Before the interface coating, the moisture content of all coarse aggregates is adjusted to the coating water absorption rate by adding water, draining, or air drying. ;

[0011] According to the target water-to-powder ratio of the interfacial reaction slurry The first stage water is mixed with the interface powder to prepare an interface reaction slurry.

[0012] Without adding fine aggregate, the interfacial reaction slurry is mixed with all the coarse aggregate so that the interfacial reaction slurry coats the outer surface of the coarse aggregate.

[0013] Fine aggregate, remaining cement, remaining fly ash and the aforementioned matrix waterproofing agent are added and mixed. Then, second-stage water, after the moisture content of coarse and fine aggregates has been corrected, and water-reducing agent are added and wet-mixed to obtain the high impermeability self-waterproof concrete.

[0014] Secondly, the present invention provides a high-permeability self-waterproof concrete structure, which is prepared by the method for preparing the high-permeability self-waterproof concrete structure.

[0015] The beneficial effects of this invention are: by using the effective surface area of ​​coarse aggregate to determine the amount of interface powder and interface waterproofing agent, the amount of material per unit area under different particle size composition and particle shape conditions is comparable, and by using the upper and lower limits of the ratio to avoid abnormal gradation leading to too little or too much material distribution.

[0016] Pre-moisten the coarse aggregate to the required water absorption rate, then press it separately. To prepare the interface slurry, avoid directly incorporating the 24-hour saturated surface-dry compensation water into the interface slurry, which would result in a higher actual water-powder ratio. Also, reduce the amount of water taken from the interface slurry by the dried aggregate during the coating process, which would result in a lower actual water-powder ratio.

[0017] A portion of the same cement-based penetrating crystalline waterproofing agent is placed in the reaction zone of the coarse aggregate interface, while the other portion is retained in the main slurry. This allows the early formation of the slurry film in the weak interface zone to share a common material basis with the subsequent crystallization reaction in the capillaries and microcracks of the main body. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of a method for preparing highly impermeable, self-waterproof concrete. Detailed Implementation

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0021] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0022] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0023] This invention provides a method for preparing highly impermeable, self-waterproof concrete, comprising: obtaining data on the particle size distribution, surface density, and particle shape of coarse aggregate; and determining the effective surface area of ​​the coarse aggregate. The coating water absorption rate of coarse aggregates from the same material source is determined according to the predetermined coating time. The coating water absorption rate For coarse aggregate, the water-to-powder ratio is reduced to the target water-to-powder ratio within the predetermined coating time. Furthermore, the ratio of water absorbed by the reference cement slurry without waterproofing agent to the dry weight of coarse aggregate;

[0024] The total mass of cementitious materials is defined as the sum of the masses of cement, fly ash, and cement-based penetrating crystalline waterproofing agent required for the concrete mix design. According to the effective surface area Determine the quality of the interface waterproofing agent separately and interface powder quality The same type of cement-based penetrating crystalline waterproofing agent is divided into interface waterproofing agent and matrix waterproofing agent. Interface cement and interface fly ash are separated from cement and fly ash, and the interface powder is composed of the interface cement, interface fly ash and interface waterproofing agent.

[0025] Before the interface coating, the moisture content of all coarse aggregates is adjusted to the coating water absorption rate by adding water, draining, or air drying. ;

[0026] According to the target water-to-powder ratio of the interfacial reaction slurry The first stage water is mixed with the interface powder to prepare an interface reaction slurry.

[0027] Without adding fine aggregate, the interfacial reaction slurry is mixed with all the coarse aggregate so that the interfacial reaction slurry coats the outer surface of the coarse aggregate.

[0028] Fine aggregate, remaining cement, remaining fly ash and the aforementioned matrix waterproofing agent are added and mixed. Then, second-stage water, after the moisture content of coarse and fine aggregates has been corrected, and water-reducing agent are added and wet-mixed to obtain the high impermeability self-waterproof concrete.

[0029] Preferably, the cement-based penetrating crystalline waterproofing agent meets the performance requirements of the corresponding product in GB / T18445—2025, and its total mass accounts for a certain percentage of the total mass of cementitious materials. The content of polycarboxylate superplasticizer is 0.5%–2.0%; the water-cement ratio of concrete is 0.38–0.42, the sand ratio is 44%–47%, the coarse aggregate particle size is 5–25 mm, the fineness modulus of fine aggregate is 2.5–2.8, and the solid mass of polycarboxylate superplasticizer accounts for 0.5%–2.0% of the total mass. 0.20% to 0.35%.

[0030] Preferably, the approximate spherical surface area and effective surface area of ​​the coarse aggregate are determined according to formula (1):

[0031] (1)

[0032] The area equivalent representative particle size for each particle size class is determined according to equation (2):

[0033] (2)

[0034] The morphology correction coefficient is determined according to formula (3):

[0035] (3)

[0036] in, The surface area is obtained by three-dimensional scanning of coarse aggregate samples from the same source, extracted according to the mass ratio of each particle size. This is the approximate spherical surface area of ​​the same sample. The same equipment parameters are used for 3D scanning, mesh reconstruction, hole repair, and noise filtering; when the material source, crushing process, and needle-like / flaky content remain largely unchanged, the verified parameters can be reused. .

[0037] Preferably, the mass of the interface waterproofing agent, the matrix waterproofing agent, and the interface powder is determined according to formulas (4) to (6):

[0038] (4)

[0039] (5)

[0040] (6)

[0041] In the formula, It is 4-12 g / m². It is 100-150 g / m²; in the formula The coefficient for converting g to kg. By using the upper and lower limits of equations (4) and (6), even when the effective surface area of ​​coarse aggregate is abnormally large or small, the interface waterproofing agent and interface powder are still kept within a reasonable ratio range between the total amount of waterproofing agent and the total amount of cementitious material. and They are 0.20 and 0.35 respectively; and The values ​​are 0.05 and 0.09, respectively.

[0042] Preferably, when the initial moisture content of the coarse aggregate is lower than the coating water absorption rate, the amount of conditioning water is determined according to formula (7):

[0043] (7)

[0044] When the initial moisture content of coarse aggregate is higher than the target value, it is drained or air-dried to satisfy equation (8):

[0045] (8)

[0046] The water in the first stage and the water in the second stage are determined according to equations (9) and (10), respectively:

[0047] (9)

[0048] (10)

[0049] If the polycarboxylate superplasticizer is a water-based agent, then the water carried by the first superplasticizer is included in the calculation. The water carried by the second water-reducing agent is included in the calculation. The corresponding amount of additional mixing water added at each stage shall be deducted. The moisture content of the coarse aggregate in formula (10) is the moisture content after conditioning. This avoids repeatedly including the moisture conditioning water volume in the first stage slurry water volume.

[0050] Preferably, the calibration of the coating water absorption rate uses the same cement-fly ash mass ratio and optional silica fume ratio as the actual interface slurry, but without adding cement-based penetrating crystalline waterproofing agent. A coarse aggregate sample from the same source, dried to constant weight at 105±5℃ and cooled to room temperature, is brought into contact with a reference cement slurry. The water-to-powder ratio of the reference slurry is taken as the actual target water-to-powder ratio. The total contact time is taken from the actual process time. At the end of the predetermined time, coarse aggregates are separated by wet screening, and the moisture content of the slurry obtained from wet screening is immediately determined. Let the mass of the reference powder be [value]. The initial water volume of the reference slurry is The dry weight of coarse aggregate used for calibration is Then it can be calculated according to formula (11):

[0051] (11)

[0052] In the formula, φw,t is the wet basis moisture content of the remaining reference slurry after wet sieving, and φw,t / (1−φw,t) is the water to dry powder mass ratio of the remaining reference slurry; Formula (11) calculates the remaining water content after contact based on the initial reference powder mass Mp. To control the systematic errors caused by slurry adhesion, sampling and early hydration, a blank group of non-absorbent particles should be set up for correction under the same time, wet sieving and weight loss procedures.

[0053] To minimize the impact of hydration water consumption on rapid determination, the time from sieving to moisture measurement was kept consistent, and a pre-validated rapid loss-in-weight method was employed. At least three parallel calibrations were performed for each material source, and the average value was taken. For ordinary low-absorption crushed stone, a mass balance method based on the same principle can also be used for verification. During production, recalibration is required when there are significant changes in the material source, crushing process, gradation, or surface cleanliness. and .

[0054] Preferably, the cement used is silicate cement or ordinary silicate cement; the fly ash used is fly ash used in cement and concrete; the silica content of the silica fume is not less than 90%. The coarse aggregate and fine aggregate meet the current standard requirements for construction pebbles, crushed stone, and construction sand, respectively; the cement-based penetrating crystalline waterproofing agent uses the same batch of powdered product and meets GB / T18445—2025; the total mass of the cement-based penetrating crystalline waterproofing agent... percentage of the total cementitious material mass 0.5% to 2.0%.

[0055] Preferably, the mass ratio of the interface cement to the interface fly ash is 2.5:1 to 4.0:1, and the interface waterproofing agent, interface cement, and interface fly ash are all included in the mass of the interface powder. .

[0056] Preferably, the total cementitious material further includes materials accounting for a certain percentage of the total cementitious material mass. 0.5% to 2.5% silica fume, and in calculating the total mass of the cementitious material. The mass of the silica fume is included in the total mass; 50% to 70% of the total mass of the silica fume is added to the interface powder as interface silica fume, and the remaining silica fume is added together with the remaining cement, remaining fly ash and matrix waterproofing agent, and the sum of the masses of the interface waterproofing agent, interface cement, interface fly ash and interface silica fume is equal to the mass of the interface powder. .

[0057] Preferably, the water-reducing agent is a polycarboxylate water-reducing agent, and is divided into a first water-reducing agent and a second water-reducing agent according to the solid mass. The first water-reducing agent accounts for 5% to 15% of the total solid mass of the water-reducing agent. The first stage water, the first water-reducing agent and the interface powder are mixed for 30 to 45 seconds to obtain the interface reaction slurry. Within 3 minutes after obtaining the interface reaction slurry, it is mixed with all the moistened coarse aggregate for 30 to 45 seconds. Fine aggregate, remaining cement, remaining fly ash and matrix waterproofing agent are added and mixed for 20 to 30 seconds. Then, the second stage water and the second water-reducing agent are added and wet-mixed for 60 to 90 seconds.

[0058] Preferably, the water-cement ratio of the high-permeability self-waterproof concrete is 0.38–0.42, the sand ratio is 44%–47%, the coarse aggregate particle size is 5–25 mm, the fine aggregate fineness modulus is 2.5–2.8, and the solid mass of the polycarboxylate superplasticizer accounts for a certain percentage of the total cementitious material mass. 0.20% to 0.35%.

[0059] It should be noted that the following embodiments use P·O42.5 ordinary Portland cement, Class II fly ash, 5-25mm continuously graded crushed stone with a surface density of 2650kg / m³, and medium sand with a fineness modulus of 2.5-2.8. The crushed stone is divided into three particle sizes: 5-10mm, 10-20mm, and 20-25mm, and their area equivalent representative particle sizes determined by formula (2) are 6.667mm, 13.333mm, and 22.222mm, respectively.

[0060] The waterproofing agent used is a powdered cement-based penetrating crystalline waterproofing agent conforming to GB / T18445—2025. The water-reducing agent is a 20% solids content liquid polycarboxylate superplasticizer aqueous solution; the proportions of the first and second water-reducing agents are calculated based on the effective solids mass of the polycarboxylate superplasticizer. The silica fume has a silica content of not less than 90%. The mixing water used meets the requirements for concrete water.

[0061] In this embodiment of the invention, a forced mixing device with an interface slurry premixing unit and a main mixing unit is used. The raw materials required for each embodiment are weighed before mixing begins; the first-stage water, the second-stage water, the first water-reducing agent aqueous solution, and the second water-reducing agent aqueous solution are metered separately. After the interface reaction slurry is prepared, it is pumped or transported by gravity to the main mixing unit, which already contains coarse aggregate.

[0062] Unless otherwise specified, the mixing time for each segment is calculated from the date all required materials for that segment are added to the corresponding mixing unit, excluding the time for weighing, conveying, and feeding materials. (Predetermined coating time) The process begins when the interfacial reactive slurry first contacts the coarse aggregate and ends when the fine aggregate and remaining cementitious materials are added. After 30–45 seconds of active coating mixing, the interfacial reactive slurry continues to maintain contact with the coarse aggregate until the appropriate mixing effect is achieved. .

[0063] The slump and spread of the concrete mixture were determined according to GB / T50080—2016. The compressive strength of the concrete was determined using 150mm cube specimens after 28 days of standard curing, according to GB / T50081—2019. Water permeability resistance and seepage height were determined according to the corresponding methods in GB / T50082—2024. The waterproofing agent and its reference concrete properties were verified according to GB / T18445—2025.

[0064] After the coarse aggregate coating step, 20 coarse aggregates were randomly selected from each batch, and images of each coarse aggregate were taken from three mutually spaced directions. The images were binarized, and the ratio of the area covered by the slurry film to the visible surface area of ​​the coarse aggregate was defined as the coverage rate of a single coarse aggregate. The arithmetic mean of the coverage rates of the 20 coarse aggregates was taken as the average coverage rate of the concrete in that batch. Each embodiment and comparative example used the same batch of raw materials, and three batches were independently prepared under the same molding and curing conditions.

[0065] Example 1, the overall concrete mix design of Examples 1 to 7 is shown in Table 1, the interface distribution and water content parameters are shown in Table 2, and the staged water use, water-reducing agent distribution and mixing parameters are shown in Table 3.

[0066] Table 1. Overall concrete mix proportions for Examples 1-7

[0067] cement / kg 294 294 296 292 300 304 302 fly ash / kg 98 98 98 96 96 80 96 Waterproofing agent / kg 8 8 6 6 4 8 2 silica fume / kg 0 0 0 6 0 8 0 Total cementitious materials / kg 400 400 400 400 400 400 400 Coarse aggregate / kg 1000 1000 1000 1000 970 1020 970 Fine aggregate / kg 835 835 835 840 860 810 860 Target effective water consumption / kg 160 160 160 158 164 152 168 Water-reducing agent solids / kg 1.00 1.00 1.00 1.10 1.40 1.20 0.80 Water-to-glue ratio 0.400 0.400 0.400 0.395 0.410 0.380 0.420 Sand ratio / % 45.5 45.5 45.5 45.7 47.0 44.3 47.0

[0068] Table 2 Interface distribution and water content parameters of Examples 1-7

[0069] Coarse aggregate three-stage proportion / % 25∶55∶20 35∶50∶15 15∶55∶30 25∶55∶20 30∶50∶20 20∶60∶20 25∶55∶20 1.20 1.30 1.10 1.25 1.35 1.15 1.20 / m² 238.42 284.77 192.40 248.35 271.29 223.09 231.26 / (g / m²) 8 10 8 8 6 7 4 / (g / m²) 130 140 120 130 110 105 100 Interface waterproofing agent / kg 1.91 2.80 1.54 1.99 1.40 1.60 0.70 Substrate waterproofing agent / kg 6.09 5.20 4.46 4.01 2.60 6.40 1.30 Interface powder / kg 30.99 36.00 23.09 32.29 29.84 23.42 23.13 Interface cement / kg 21.81 25.30 15.39 20.03 20.32 12.98 16.82 Interfacial fly ash / kg 7.27 7.90 6.16 6.67 8.12 3.24 5.61 Interface silica fume / kg 0 0 0 3.60 0 5.60 0 / s 90 120 60 90 180 75 90 0.39 0.40 0.39 0.39 0.41 0.38 0.42 / % 0.55 0.65 0.45 0.55 0.70 0.60 0.50 Initial moisture content of coarse aggregate / % 0.30 0.10 0.90 0.55 0.20 0.40 0.30 Coarse aggregate 24h water absorption rate / % 0.80 1.00 0.70 0.80 1.10 0.90 0.80 Current moisture content of fine aggregate / % 1.20 1.00 2.00 1.50 1.00 1.20 1.20 Fine aggregate 24h water absorption rate / % 1.50 1.60 1.40 1.50 1.80 1.40 1.80 Humidification water / kg 2.50 5.50 not applicable 0 4.85 2.04 1.94 Phase 1 Total Water / kg 12.09 14.40 9.00 12.59 12.24 8.90 9.71 Second phase total water / kg 152.92 154.11 148.49 147.91 162.52 147.78 166.36

[0070] Table 3. Water-reducing agent, water volume, and stirring parameters for Examples 1-7

[0071] First water-reducing agent solid content / % 10 15 5 10 15 5 10 First water-reducing agent aqueous solution / kg 0.50 0.75 0.25 0.55 1.05 0.30 0.40 First water-reducing agent introduces water / kg 0.40 0.60 0.20 0.44 0.84 0.24 0.32 Add water / kg for the first stage 11.69 13.80 8.80 12.15 11.40 8.66 9.39 Second water-reducing agent aqueous solution / kg 4.50 4.25 4.75 4.95 5.95 5.70 3.60 Second water-reducing agent introduces water / kg 3.60 3.40 3.80 3.96 4.76 4.56 2.88 Second stage: Add additional water / kg 149.32 150.71 144.69 143.95 157.76 143.22 163.48 Interface slurry mixing / s 35 45 30 40 45 30 35 Active coating mixing / s 40 45 30 40 45 35 40 Mix after adding the remaining dry material / s 25 30 20 25 30 20 25 Final wet mix / s 75 90 60 75 90 60 75

[0072] According to Table 1, weigh out 294 kg of cement, 98 kg of fly ash, 8 kg of waterproofing agent, 1000 kg of coarse aggregate, 835 kg of fine aggregate, and 1.00 kg of solid polycarboxylate superplasticizer. The mass ratio of the three coarse aggregate sizes is 25:55:20. The composition was calibrated using 3D scanning. Calculated according to formulas (1) to (3) and .Pick and According to formulas (4) to (6), 1.91 kg of interface waterproofing agent, 6.09 kg of matrix waterproofing agent and 30.99 kg of interface powder are calculated; 21.81 kg and 7.27 kg are taken from cement and fly ash respectively, and combined with the interface waterproofing agent to form the interface powder.

[0073] by and Calibration obtained Add 2.50 kg of conditioning water to the coarse aggregate with an initial moisture content of 0.30%, mix well, seal and let stand for 30 minutes, and then mix once after standing for 15 minutes to bring the moisture content of the coarse aggregate to 0.55%.

[0074] The first water-reducing agent has a solid content of 0.10 kg, corresponding to a 20% solid content water-reducing agent aqueous solution of 0.50 kg, of which 0.40 kg of water is introduced. The second water-reducing agent has a solid content of 0.90 kg, corresponding to a 4.50 kg water-reducing agent aqueous solution, of which 3.60 kg of water is introduced. Therefore, the additional water added in the first stage is 11.69 kg, and the additional water added in the second stage is 149.32 kg.

[0075] 11.69 kg of water, 0.50 kg of the first water-reducing agent aqueous solution, and 30.99 kg of interface powder were added to the interface slurry premixing unit. After the addition was completed, the mixture was stirred for 35 seconds to obtain the interface reaction slurry.

[0076] All the conditioned coarse aggregate was added to the main mixing unit and pre-mixed for 15 seconds. No more than 3 minutes after the interfacial reaction slurry was prepared, the slurry was added. After the interfacial reaction slurry was added, it was mixed for 40 seconds, and then kept in contact with the coarse aggregate until the total contact time reached 90 seconds.

[0077] Fine aggregate, remaining cement, remaining fly ash, and 6.09 kg of matrix waterproofing agent were added, and mixed for 25 seconds after the addition was completed. Then, 149.32 kg of water for the second stage and 4.50 kg of the second water-reducing agent aqueous solution were added, and wet-mixed for 75 seconds after the addition was completed to obtain concrete E1 of Example 1. The concrete was poured into the mold, vibrated, covered and kept moist for 24 hours, then demolded, and cured at 20±2℃ and relative humidity not less than 95%.

[0078] Example 2: Concrete E2 of Example 2 was prepared according to the parameters listed in Tables 1-3. Specifically, the mass ratio of the three coarse aggregate sizes was 35:50:15. Calculations yielded and .Pick and The interface waterproofing agent is 2.80 kg, the matrix waterproofing agent is 5.20 kg, and the interface powder is 36.00 kg; the interface powder consists of 2.80 kg of interface waterproofing agent, 25.30 kg of interface cement and 7.90 kg of interface fly ash.

[0079] The coarse aggregate with an initial moisture content of 0.10% was conditioned to 0.65% using 5.50 kg of conditioning water. The first and second water-reducing agent aqueous solutions were 0.75 kg and 4.25 kg, respectively, with corresponding additional water added in the first and second stages at 13.80 kg and 150.71 kg, respectively. The interface reaction slurry was stirred for 45 seconds, and no more than 3 minutes after its preparation, it was mixed with all the coarse aggregate. Active coating and mixing were performed for 45 seconds, maintaining contact until the total contact time reached 120 seconds. After adding the remaining dry material, mixing was performed for 30 seconds, followed by adding the second stage additional water and the second water-reducing agent aqueous solution, and then wet mixing for 90 seconds. The resulting concrete was molded and cured according to the conditions of Example 1.

[0080] Example 3: Concrete E3 of Example 3 was prepared according to the parameters listed in Tables 1-3. The mass ratio of the three coarse aggregate sizes was 15:55:30. Calculations yielded and The 23.09 kg interface powder consists of 1.54 kg interface waterproofing agent, 15.39 kg interface cement and 6.16 kg interface fly ash, and the matrix waterproofing agent is 4.46 kg.

[0081] The initial moisture content of the coarse aggregate was 0.90%, which is higher than... The concrete was spread out and air-dried, and the moisture content was retested until it reached 0.45%. Approximately 4.50 kg of water was removed per cubic meter of concrete compared to the initial state. The first and second water-reducing agent aqueous solutions were 0.25 kg and 4.75 kg, respectively. Additional water was added in the first and second stages, respectively, at amounts of 8.80 kg and 144.69 kg. The interface reaction slurry was stirred for 30 seconds, actively mixed with all coarse aggregate for 30 seconds, and kept in contact for 60 seconds. After adding the remaining dry material, it was mixed for 20 seconds, and finally wet-mixed for 60 seconds. The resulting concrete was molded and cured according to the conditions of Example 1.

[0082] Example 4: Concrete E4 of Example 4 was prepared according to the parameters listed in Tables 1-3. The total amount of silica fume in this example was 6 kg, of which 60% (3.60 kg) was added as interface silica fume to the interface powder, and the remaining 2.40 kg was added to the main cementitious material. The coarse aggregate gradation was the same as in Example 1. Calculations yielded The 32.29 kg interface powder consists of 1.99 kg interface waterproofing agent, 20.03 kg interface cement, 6.67 kg interface fly ash, and 3.60 kg interface silica fume, while the matrix waterproofing agent is 4.01 kg.

[0083] The current moisture content of coarse aggregate is equal to No further water was added for conditioning. The aqueous solutions of the first and second water-reducing agents were 0.55 kg and 4.95 kg, respectively. Additional water was added in the first and second stages, respectively, at 12.15 kg and 143.95 kg. The interface reaction slurry was stirred for 40 seconds, actively coated and mixed with all coarse aggregates for 40 seconds, and kept in contact for 90 seconds. After adding the remaining dry materials, it was mixed for 25 seconds, and finally wet-mixed for 75 seconds. The resulting concrete was molded and cured according to the conditions of Example 1.

[0084] Example 5: Concrete E5 of Example 5 was prepared according to the parameters listed in Tables 1 to 3. The mass ratio of the three coarse aggregate sizes was 30:50:20. Calculations yielded The 29.84 kg interface powder consists of 1.40 kg interface waterproofing agent, 20.32 kg interface cement and 8.12 kg interface fly ash, and the matrix waterproofing agent is 2.60 kg.

[0085] The moisture content of the coarse aggregate was adjusted from 0.20% to [a specific value] using 4.85 kg of conditioning water. The aqueous solutions of the first and second water-reducing agents were 1.05 kg and 5.95 kg, respectively. Additional water was added in the first and second stages, respectively, at 11.40 kg and 157.76 kg. The interface reaction slurry was stirred for 45 seconds, actively coated and mixed with all coarse aggregates for 45 seconds, and kept in contact for 180 seconds. After adding the remaining dry materials, it was mixed for 30 seconds, and finally wet-mixed for 90 seconds. The resulting concrete was molded and cured according to the conditions of Example 1.

[0086] Example 6: Concrete E6 of Example 6 was prepared according to the parameters listed in Tables 1-3. The total amount of silica fume in this example was 8 kg, of which 70%, or 5.60 kg, was added as interface silica fume to the interface powder, and the remaining 2.40 kg was added to the main cementitious material. The mass ratio of the three coarse aggregate sizes was 20:60:20. Calculations yielded The 23.42 kg interface powder consists of 1.60 kg interface waterproofing agent, 12.98 kg interface cement, 3.24 kg interface fly ash, and 5.60 kg interface silica fume, while the matrix waterproofing agent is 6.40 kg.

[0087] Use 2.04 kg of conditioning water to adjust the moisture content of the coarse aggregate from 0.40% to... The aqueous solutions of the first and second water-reducing agents were 0.30 kg and 5.70 kg, respectively. Additional water was added in the first and second stages, amounting to 8.66 kg and 143.22 kg, respectively. The interface reaction slurry was stirred for 30 seconds, actively coated and mixed with all coarse aggregates for 35 seconds, and kept in contact for 75 seconds. After adding the remaining dry materials, it was mixed for 20 seconds, and finally wet-mixed for 60 seconds. The resulting concrete was molded and cured according to the conditions of Example 1.

[0088] Example 7: Concrete E7 of Example 7 was prepared according to the parameters listed in Tables 1 to 3. This example illustrates the implementation method when the total dosage of waterproofing agent and the solid dosage of water-reducing agent are at the lower limit of the stated range. The mass ratio of the three coarse aggregate sizes is 25:55:20. Calculations yielded The 23.13 kg interface powder consists of 0.70 kg interface waterproofing agent, 16.82 kg interface cement and 5.61 kg interface fly ash, and the matrix waterproofing agent is 1.30 kg.

[0089] The moisture content of the coarse aggregate was adjusted from 0.30% to [a specific value] using 1.94 kg of conditioning water. The aqueous solutions of the first and second water-reducing agents were 0.40 kg and 3.60 kg, respectively. Additional water was added in the first and second stages, respectively, at 9.39 kg and 163.48 kg. The interface reaction slurry was stirred for 35 seconds, actively mixed with all coarse aggregates for 40 seconds and kept in contact for 90 seconds; the remaining dry materials were added and mixed for 25 seconds, followed by a final wet mix of 75 seconds. The resulting concrete was molded and cured according to the conditions of Example 1.

[0090] Comparative Example 1 used the same overall concrete mix proportion, coarse aggregate gradation, and aggregate moisture content as Example 1. The coarse and fine aggregates were mixed for 30 seconds, then all cement, fly ash, and waterproofing agent were added and dry-mixed for 30 seconds. Next, 161.01 kg of additional mixing water and 5.00 kg of polycarboxylate superplasticizer aqueous solution were added, with the 4.00 kg of water introduced by the superplasticizer aqueous solution included in the total mixing water. The mixture was wet-mixed for 120 seconds to obtain concrete C1 of Comparative Example 1. C1 was molded and cured according to the conditions of Example 1.

[0091] Comparative Example 2 used the same total concrete mix proportion, coarse aggregate gradation, moisture content, and feeding sequence as Example 2, but did not follow the same procedures as Example 2. The dosages of the interface waterproofing agent and interface powder were adjusted, while the amounts of interface waterproofing agent (1.90 kg) and interface powder (31.00 kg) were fixed. The interface powder consisted of 1.90 kg of interface waterproofing agent, 22.17 kg of interface cement, and 6.93 kg of interface fly ash, while the matrix waterproofing agent was 6.10 kg. The total water content in the first stage was calculated as follows: The total water content for the first stage was calculated to be 12.40 kg, including 0.75 kg of the first water-reducing agent aqueous solution, 0.60 kg of water introduced, and an additional 11.80 kg of water added in the first stage. The total water content for the second stage was adjusted accordingly to 156.11 kg, including 4.25 kg of the second water-reducing agent aqueous solution, 3.40 kg of water introduced, and an additional 152.71 kg of water added in the second stage. The mixing time for each stage was the same as in Example 2, resulting in concrete C2 of Comparative Example 2.

[0092] Comparative Example 3 used the same total concrete mix proportion and preparation method as Example 1, but all 8 kg of waterproofing agent was used as interface waterproofing agent, and no matrix waterproofing agent was added to the main cementitious material. The total amount of interface powder was kept at 30.99 kg, which consisted of 8.00 kg of interface waterproofing agent, 17.24 kg of interface cement, and 5.75 kg of interface fly ash. The remaining parameters were the same as in Example 1, and concrete C3 was obtained in Comparative Example 3.

[0093] Comparative Example 4 used the same concrete mix proportions and preparation methods as Example 1, but no interface waterproofing agent was added to the interface powder. All 8 kg of waterproofing agent was added to the main cementitious material as a matrix waterproofing agent. The total amount of interface powder was kept at 30.99 kg, consisting of 23.24 kg of interface cement and 7.75 kg of interface fly ash. The remaining parameters were the same as in Example 1, resulting in concrete C4 for Comparative Example 4.

[0094] Comparative Example 5 uses the same total mix proportion, effective surface area, interfacial powder composition and feeding sequence as Example 2, but instead of using 5.50 kg of conditioning water to pre-condition the coarse aggregate to 0.65%, it directly uses coarse aggregate with an initial moisture content of 0.10% for coating; the total water in the first stage is still 14.40 kg, and the total water in the second stage is still 154.11 kg, with the remaining parameters being the same as in Example 2, to obtain concrete C5 of Comparative Example 5.

[0095] For concrete E1 to E7 and C1 to C5, the average coverage, slump or spread, 28-day compressive strength, water permeability resistance, and water seepage height were determined according to the above test methods. All groups of tests used the same batch of raw materials, the same specimen size, and the same molding and curing conditions. Except for the technical characteristics explicitly changed in each comparative example, all other conditions remained consistent.

[0096] Table 4 Performance results of E1~E7 and C1~C5

[0097] E1 91.8±1.9 190±8 49.1±1.4 P12 14.8±2.0 E2 93.2±1.7 180±9 49.6±1.5 P12 13.8±1.8 E3 88.9±2.4 205±8 48.7±1.4 P10 17.2±2.4 E4 93.8±1.6 185±8 51.8±1.5 ≥P12 11.9±1.6 E5 94.5±1.5 215±10 46.6±1.6 P10 16.8±2.3 E6 91.3±2.0 175±9 54.0±1.7 ≥P12 10.4±1.5 E7 87.5±2.7 200±11 44.7±1.5 P8 21.5±3.2 C1 80.4±4.2 195±9 46.2±1.6 P8 22.2±3.6 C2 86.7±3.0 188±10 47.1±1.7 P10 18.6±2.8 C3 90.2±2.3 174±10 48.0±1.6 P10 18.1±2.7 C4 91.0±2.1 190±9 48.3±1.5 P10 18.8±2.9 C5 81.9±4.0 162±12 45.8±1.8 P8 22.8±3.8

[0098] Example 1 and Comparative Example 1 had the same total mix proportion and total amount of waterproofing agent. After distributing the interface powder according to the effective surface area and pre-conditioning, the average coverage of E1 was about 11 percentage points higher than that of C1, the 28-day compressive strength was about 6% higher, and the maximum water penetration height was about 33% lower. This trend mainly came from the reduction in the continuity of the slurry film on the coarse aggregate surface and the pore connectivity of the interface transition zone, rather than the increase in the total amount of waterproofing agent.

[0099] The difference between Example 2 and Comparative Example 2 lies in whether the interface dosage was adjusted to accommodate a larger effective surface area. E2 showed an approximately 6.5 percentage point increase in coverage compared to C2, and a approximately 26% decrease in maximum water penetration height, indicating that a fixed interface powder quality, under conditions of finer gradation and a larger morphology correction coefficient, may result in insufficient material feeding per unit area. Compared to Comparative Example 5, pre-conditioning in Example 2 prevented the dry coarse aggregate from rapidly drawing water from the interface slurry, resulting in an approximately 11 percentage point increase in coverage, an approximately 18 mm increase in slump, and a reduction in water penetration height.

[0100] Comparative Examples 3 and 4 involved applying the waterproofing agent entirely to either the interface powder or the main cementitious material. The immediate coverage of both was not significantly lower than E1, but the maximum seepage height was higher than E1, indicating that coverage only reflects the integrity of the slurry film in the fresh mixing stage and cannot solely represent the impermeability of hardened concrete. Retaining active components simultaneously in both the interface zone and the main slurry is more beneficial for simultaneously restricting both interface channels and main capillary channels.

[0101] Examples 4 and 6, which have both a low water-binder ratio and a silica fume distribution at the interface and bulk, exhibit better impermeability than the silica fume-free examples.

[0102] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing high-permeability, self-waterproof concrete, characterized in that, Includes the following steps: Obtain the particle size distribution, surface density, and particle shape data of the coarse aggregate, and determine the effective surface area of ​​the coarse aggregate. The coating water absorption rate of coarse aggregates from the same material source is determined according to the predetermined coating time. The coating water absorption rate For coarse aggregate, the water-to-powder ratio is reduced to the target water-to-powder ratio within the predetermined coating time. Furthermore, the ratio of water absorbed by the reference cement slurry without waterproofing agent to the dry weight of coarse aggregate; The total mass of cementitious materials is defined as the sum of the masses of cement, fly ash, and cement-based penetrating crystalline waterproofing agent required for the concrete mix design. According to the effective surface area Determine the quality of the interface waterproofing agent separately and interface powder quality The same type of cement-based penetrating crystalline waterproofing agent is divided into interface waterproofing agent and matrix waterproofing agent. Interface cement and interface fly ash are separated from cement and fly ash, and the interface powder is composed of the interface cement, interface fly ash and interface waterproofing agent. Before the interface coating, the moisture content of all coarse aggregates is adjusted to the coating water absorption rate by adding water, draining, or air drying. ; According to the target water-to-powder ratio of the interfacial reaction slurry The first stage water is mixed with the interface powder to prepare an interface reaction slurry; Without adding fine aggregate, the interfacial reaction slurry is mixed with all the coarse aggregate so that the interfacial reaction slurry coats the outer surface of the coarse aggregate. Fine aggregate, remaining cement, remaining fly ash and the aforementioned matrix waterproofing agent are added and mixed. Then, second-stage water, after the moisture content of coarse and fine aggregates has been corrected, and water-reducing agent are added and wet-mixed to obtain the high impermeability self-waterproof concrete.

2. The preparation method according to claim 1, characterized in that, The effective surface area Determine according to the following formula: ； Among them, each particle size represents the particle size. Determine according to the following formula: ； Morphology correction factor Determine according to the following formula: ； In the formula, For granular indexing; Total number of particles; This represents the approximate spherical surface area of ​​the coarse aggregate, in m². For the first Dry weight of coarse aggregate, in kg; The surface density of coarse aggregate is expressed in kg / m³. and The first The lower and upper limits of particle size for particle size classification, in meters (m). For the first The area equivalent of the particle size is represented by the particle size in meters (m). This is a dimensionless morphology correction factor; The measured surface area is obtained by three-dimensional scanning of coarse aggregate samples from the same source, extracted according to the mass ratio of each particle size. Let be the approximate spherical surface area of ​​the sample.

3. The preparation method according to claim 1, characterized in that, The quality of the interface waterproofing agent Quality of substrate waterproofing agent and interface powder quality Determine them according to the following formulas respectively: ； ； ； In the formula, The total mass of the cement-based penetrating crystalline waterproofing agent is expressed in kg. The total mass of the cementitious material is expressed in kg. The amount of waterproofing agent used per unit effective surface area; The amount of interfacial powder used per unit effective surface area.

4. The preparation method according to claim 1, characterized in that, The predetermined covering time The water absorption rate of the coating is 60–180 s. The target water-to-powder ratio is achieved by using coarse aggregate from the same source to a water-to-powder ratio. The reference cement slurry, which does not contain waterproofing agents, is mixed for the predetermined coating time. The calibration was performed based on the difference in moisture content of the reference cement slurry before and after mixing; when the initial moisture content of the coarse aggregate was... Below the stated water absorption rate At that time, the amount of water used for adjusting the coarse aggregate moisture content Determine according to the following formula: ； When the initial moisture content Higher than the coating water absorption rate At that time, the moisture content of coarse aggregate is reduced by draining or air drying until the following conditions are met: ； First stage water volume Second stage water volume Determine them according to the following formulas respectively: ； ； In the formula, The value ranges from 0.36 to 0.

42. The target effective water consumption is expressed in kg. This represents the current moisture content of the conditioned coarse aggregate. and The values ​​are the 24-hour water absorption rates of coarse and fine aggregates relative to their dry weight, respectively. This represents the current moisture content of the fine aggregate relative to its dry weight. and The dry weights of coarse and fine aggregates are respectively, in kg; when the water-reducing agent is a liquid aqueous solution, the water it introduces is included in the corresponding stage. or .

5. The preparation method according to claim 1, characterized in that, The total mass of the cement-based penetrating crystalline waterproofing agent percentage of the total cementitious material mass 0.5% to 2.0%.

6. The preparation method according to claim 1, characterized in that, The mass ratio of the interface cement to the interface fly ash is 2.5:1 to 4.0:1, and the interface waterproofing agent, interface cement, and interface fly ash are all included in the mass of the interface powder. .

7. The preparation method according to claim 6, characterized in that, The total cementitious material also includes components accounting for a certain percentage of the total cementitious material mass. 0.5% to 2.5% silica fume, and in calculating the total mass of the cementitious material. The mass of the silica fume is included in the total mass; 50% to 70% of the total mass of the silica fume is added to the interface powder as interface silica fume, and the remaining silica fume is added together with the remaining cement, remaining fly ash and matrix waterproofing agent, and the sum of the masses of the interface waterproofing agent, interface cement, interface fly ash and interface silica fume is equal to the mass of the interface powder. .

8. The preparation method according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate water-reducing agent, and is divided into a first water-reducing agent and a second water-reducing agent according to the solid mass. The first water-reducing agent accounts for 5% to 15% of the total solid mass of the water-reducing agent. The first stage water, the first water-reducing agent and the interface powder are mixed for 30 to 45 seconds to obtain the interface reaction slurry. Within 3 minutes after obtaining the interface reaction slurry, it is mixed with all the moistened coarse aggregate for 30 to 45 seconds. Fine aggregate, remaining cement, remaining fly ash and matrix waterproofing agent are added and mixed for 20 to 30 seconds. Then, the second stage water and the second water-reducing agent are added and wet-mixed for 60 to 90 seconds.

9. The preparation method according to claim 1, characterized in that, The high-permeability self-waterproof concrete has a water-cement ratio of 0.38–0.42, a sand ratio of 44%–47%, a coarse aggregate particle size of 5–25 mm, a fine aggregate fineness modulus of 2.5–2.8, and the solid mass of the polycarboxylate superplasticizer accounts for a certain percentage of the total cementitious material mass. 0.20% to 0.35%.

10. A high-permeability, self-waterproof concrete structure, characterized in that, It is prepared by any one of claims 1 to 9.

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