Salt-erosion-resistant high-performance pervious concrete and preparation method thereof

Abstract

The application discloses a kind of salt-resistant high-performance pervious concrete and preparation method thereof, belong to pervious concrete material and its preparation technical field.The pervious concrete includes: Portland cement, graded gravel aggregate, composite mineral admixture, double-fiber compound system, water-based surface treatment agent, superplasticizer, mixing water by mass fraction;The composite mineral admixture is compounded by fly ash and slag powder, the double-fiber compound system is compounded by polypropylene coarse fiber and micro steel fiber, and the surface modification additive is compounded by water-based silicone-acrylate emulsion, nano-silica and inorganic wear-resistant filler.The preparation method includes aggregate pretreatment, dry material premixing, wet mixing, synchronous protection of surface layer and segmented moisture curing steps.The application can be widely applied to coastal rural roads, leisure squares, landscape paths and other pervious pavement engineering through the synergistic effect of internal mineral dense chlorine resistance, double-fiber hierarchical toughening and surface layer hydrophobic self-cleaning.

Description

Technical Field

[0001] This invention relates to the field of permeable concrete materials and their preparation technology, specifically to a high-performance permeable concrete and its preparation method that combines salt corrosion resistance, heavy load resistance, self-cleaning and anti-clogging properties, and is suitable for simple construction conditions in rural areas. It is applicable to road hardening, leisure squares, landscape walkways and other engineering scenarios in the improvement of the living environment in coastal rural areas. Background Technology

[0002] Permeable concrete, as an eco-friendly pavement material, can effectively mitigate surface runoff and replenish groundwater, and is widely used in urban and rural roads and landscape projects. However, the pores of permeable concrete are easily clogged by sludge and debris, leading to a decrease in its permeability. At the same time, it also faces durability problems caused by chloride ion corrosion in coastal high-salt spray environments.

[0003] Existing anti-clogging permeable concrete solutions primarily alleviate clogging problems by reducing matrix porosity and incorporating functional fibers for water conduction. For example, Chinese patent application CN106186943A uses a combination of crushed stone and quartz sand to construct a small-pore system, combined with hydrophilic modified polypropylene fibers to achieve both permeability and anti-clogging properties. However, this type of technical solution still has significant limitations in coastal rural settings: First, there is a lack of specific design for salt corrosion resistance. The mineral admixtures in this scheme are used in low amounts and are only used as auxiliary modifiers. They cannot effectively fill the capillary pores inside the concrete or block the chloride ion penetration channels. In the high salt spray environment of the coast, salt corrosion expansion, aggregate interface cracking, and surface sanding and peeling are likely to occur, which will significantly shorten the service life of the pavement.

[0004] Secondly, it lacks the ability to withstand heavy loads and impacts. This design uses only a single modified polypropylene fiber in extremely low amounts, which mainly serves to conduct water and cannot effectively improve the flexural strength and impact resistance of concrete. It is difficult to withstand repeated rolling by heavy machinery such as agricultural trucks and tractors, and rural heavy-load road sections are prone to slab breakage and surface damage.

[0005] Third, the anti-blocking mechanism has limitations. This solution relies on the small pore structure inside the substrate to block large particles of dirt, but mud, weeds and stains can still easily accumulate on the road surface. Long-term accumulation of dirt will gradually block the surface pores, and it does not have self-cleaning ability. In rural areas, cleaning conditions are limited, and the later maintenance is difficult and costly.

[0006] Fourth, the construction adaptability is insufficient. The raw material composition of this scheme is complex. Components such as quartz sand and redispersible latex powder have high requirements for batching accuracy. The construction process requires precise mixing in stages, which places high demands on the technical level of equipment and personnel. It is difficult to adapt to the site conditions of small-scale construction equipment and limited skills of workers in rural areas.

[0007] Fifth, the scheme lacks differentiated application scenarios. It fails to design tiered formulations for different load levels, making it difficult to simultaneously meet the performance requirements and cost control of heavy-duty roads, leisure plazas, and scenic walkways.

[0008] In summary, existing permeable concrete technology cannot simultaneously solve the four core pain points of coastal rural roads: salt corrosion damage, heavy load cracking, pore blockage, and poor construction adaptability. There is an urgent need to develop targeted high-performance permeable concrete materials and preparation processes. Summary of the Invention

[0009] In response to the technical shortcomings of ordinary concrete pavements in rural coastal areas of western Guangdong, such as salt corrosion cracking, sanding and peeling, easy accumulation of dirt and blockage of permeability, poor construction adaptability and high maintenance costs, this invention provides a salt corrosion resistant high-performance permeable concrete and its preparation method suitable for the improvement of the living environment in rural coastal areas.

[0010] To address the aforementioned problems, this invention provides a high-performance permeable concrete suitable for salt corrosion resistance, comprising the following raw material components by weight: 280-330 parts of silicate cement; Graded crushed stone aggregate: 1450–1550 parts; 70-110 parts of composite mineral admixture; The dual-fiber compound system comprises 2.8–5.0 parts; 12-20 parts of water-based surface treatment agent; High-efficiency water-reducing agent, 3.0–5.0 parts; Mix with 100-130 parts of water.

[0011] Furthermore, the composite mineral admixture is prepared by mixing fly ash and slag powder at a mass ratio of 1:0.8 to 1.1. Fly ash has a ball-bearing lubrication effect, which can optimize the workability of permeable concrete mixtures, reduce slurry viscosity, and reduce the agglomeration of steel fibers and polypropylene fibers during mixing. At the same time, the active components of fly ash can undergo a secondary pozzolanic reaction with Ca(OH)2 produced by cement hydration to generate hydrated calcium silicate and hydrated calcium aluminate gels, which fill the micron-level capillaries inside the concrete and block chloride ion penetration channels. Slag powder has a higher activity index, faster hydration speed, and significantly improved early strength; it is rich in CaO and Al2O3, and has a stronger ability to consume calcium hydroxide produced by cement hydration, significantly reducing the alkalinity of the system and inhibiting alkali-aggregate reaction in coastal environments; slag powder has a better pore-refining effect than fly ash, which can further reduce the chloride ion diffusion coefficient. The mass ratio of fly ash to slag powder is limited to 1:0.8–1.1. Fly ash improves the workability of the mixture and helps fill capillary pores through spherical microspheres, while slag powder enhances early strength and strengthens the calcium hydroxide consumption capacity to block chloride ion corrosion. Within this ratio range, the two form a complementary and synergistic effect of pozzolanic activity. If the slag powder content is less than 0.8 times that of fly ash, the early strength of the system is insufficient and the salt corrosion resistance decreases. If the slag powder content is more than 1.1 times that of fly ash, the viscosity of the mixture increases significantly, fibers are prone to agglomeration, and the heat of hydration increases, easily leading to thermal shrinkage cracks. This ratio range can simultaneously balance the workability, early mechanical strength, and long-term chloride ion corrosion resistance of permeable concrete.

[0012] Furthermore, the dual-fiber composite system comprises coarse polypropylene fibers and fine steel fibers blended at a mass ratio of 1:1.5 to 4.5. Coarse polypropylene fibers have a low elastic modulus and good dispersibility, uniformly distributed at the interface between the concrete surface and the slurry. They primarily constrain early-stage plastic shrinkage cracks in concrete and inhibit the initiation of surface micro-cracks during paving and curing. The fibers are soft, making them less likely to scratch aggregates or clump during mixing, thus improving the workability of the mixture. However, polypropylene fibers themselves have weak tensile, flexural, and impact resistance, making them unable to withstand repeated heavy-load compaction by agricultural machinery. Relying solely on polypropylene fibers is insufficient to improve the overall structural strength of the pavement, and under heavy loads, slab breakage and surface damage are likely to occur. Fine steel fibers have a much higher elastic modulus and tensile strength than polypropylene fibers. They penetrate the concrete matrix, forming a three-dimensional rigid toughening skeleton, significantly improving 28-day flexural strength, impact resistance, and fatigue resistance, making them suitable for long-term reciprocating compaction by agricultural trucks and tractors. The steel fibers can bridge macroscopic cracks caused by loads, preventing crack propagation. However, steel fibers have high density and rigidity. If the dosage or proportion is too high, they are prone to clumping and agglomeration during mixing, disrupting the continuous and interconnected pores of permeable concrete, reducing the permeability coefficient, and significantly increasing material costs. By limiting the mass ratio of coarse polypropylene fibers to fine steel fibers to 1:1.5–4.5, the coarse polypropylene fibers primarily inhibit surface plastic shrinkage microcracks during the concrete curing stage, while the fine steel fibers form a rigid and toughening skeleton within the matrix, improving flexural strength, impact resistance, and heavy-load fatigue performance. Within this ratio range, they form a synergistic toughening system that prevents surface microcracks and internal macrocracks. If the proportion of fine steel fibers is less than 1.5 times that of polypropylene fibers, the matrix's resistance to heavy-load cracking is insufficient, and coastal salt erosion easily penetrates the interior along load-bearing cracks. If the proportion of fine steel fibers is greater than 4.5 times that of polypropylene fibers, surface plastic cracks are difficult to control, and the steel fibers easily agglomerate and clog permeable pores, significantly increasing material costs. This ratio range can simultaneously balance early-stage crack prevention, mid-to-late-stage mechanical bearing capacity, and permeability of permeable concrete.

[0013] Furthermore, the water-based surface treatment agent is formulated from water-based silicone-acrylic emulsion, nano-silica, and inorganic wear-resistant filler, and contains no organic solvents; the mass ratio of water-based silicone-acrylic emulsion, nano-silica, and inorganic wear-resistant filler is 30:3:3; the inorganic wear-resistant filler is white corundum micro powder and / or silicon carbide micro powder. As a continuous film-forming substrate, the solvent-free water-based silicone-acrylic emulsion combines the advantages of high adhesion of acrylic resin and low surface energy hydrophobicity of siloxane, enabling it to uniformly wet the inner walls of the capillary pores on the surface of permeable concrete, forming a continuous, flexible, ultra-thin protective film after curing; it has a strong interface bond with cement hydration products and will not peel off even after long-term exposure to agricultural machinery rolling and alternating wet and dry conditions. Simultaneously, the emulsion itself does not contain organic solvents such as ethanol, alcohol ethers, or aromatics, meeting the requirements for green construction and pollution-free management in rural areas. If the emulsion content is too low, a complete and continuous film cannot be formed, resulting in a significant reduction in hydrophobic and chloride-barrier effects. If the emulsion content is too high, the wear-resistant filler and nano-silica are diluted, leading to insufficient surface wear resistance and micro / nano hydrophobic structure, making the road surface prone to scratches and reducing self-cleaning performance. Nano-silica particles are extremely small, filling the micro-gaps within the silicone-acrylic emulsion and the nano-scale pores on the concrete surface, constructing a micro / nano composite rough structure, increasing the water contact angle of the coating, and achieving rainwater self-cleaning. Simultaneously, the nanoparticles can block the capillary channels on the concrete surface, forming a second chloride ion barrier, working synergistically with the internal composite mineral admixtures to improve overall salt corrosion resistance. The dosage of nano-silica should not be too high; excessive amounts will cause instability and stratification of the emulsion system, easily clogging the spray gun during application, making it suitable for simple rural spraying equipment. Insufficient dosage will prevent the construction of a hydrophobic microstructure, allowing sludge to adhere to the road surface and resulting in a loss of anti-clogging and self-cleaning effects. White fused alumina micro powder has high hardness and strong chemical inertness, resisting seawater chloride ion corrosion, increasing the Mohs hardness of the coating surface, and resisting scratches from agricultural machinery tires and hard objects. Silicon carbide micro powder has a low coefficient of friction, reducing long-term wear and tear on the road surface. The two can be used alone or in combination. The filler is only a functional powder dispersed inside the silicone-acrylic organic film, does not participate in cement hydration, and will not block the permeable pores of the concrete. Excessive filler will disrupt the continuity of the silicone-acrylic emulsion film formation, making the film brittle and prone to peeling off; insufficient filler will result in insufficient surface wear resistance, and the hydrophobic protective layer will wear out rapidly after long-term use.

[0014] Furthermore, the graded crushed stone aggregate is continuously graded crushed stone after grading and screening, and the moisture content of the aggregate after pretreatment is ≤2%.

[0015] On the other hand, the present invention also provides a method for preparing the above-mentioned salt-resistant high-performance permeable concrete, comprising the following steps: S1 Aggregate Pretreatment: The crushed stone aggregate is graded and screened, rinsed with clean water to remove surface mud and powder, and naturally dried until the aggregate moisture content is ≤2% for later use; Natural drying of aggregate to ≤2% moisture content can accurately stabilize the water-cement ratio of the system, prevent fiber agglomeration, inhibit surface plastic cracking, and reduce mud blockage of permeable pores, while taking into account the mechanical strength of concrete, salt corrosion resistance and durability, and on-site construction adaptability.

[0016] S2 Dry premix: Put silicate cement, composite mineral admixture, and dual fiber compound system into a forced mixer and dry mix for 90-120 seconds to ensure that the fibers are evenly dispersed and do not agglomerate. S3 Wet Mixing and Molding: Add mixing water and high-efficiency water-reducing agent and stir continuously for 60 seconds, then slowly add water-based surface treatment agent. The total wet mixing time is ≥180 seconds to obtain a uniform and stable permeable concrete mixture. S4 Simultaneous protection during paving and surface treatment: After paving the mixture, use a plate vibrator to lightly vibrate it, and spray the diluted water-based surface treatment agent of the same type evenly before the initial setting of the concrete. S5 Segmented Moisture Retention and Maintenance: After paving, cover with geotextile and continuously spray water for 7 days to maintain moisture retention. In low-temperature environments, cover with an insulation film. After the maintenance period, the road can be opened to traffic.

[0017] Furthermore, in step S2, a small forced mixer is used for dry mixing. During the dry mixing process, the fibers are dispersed by feeding them in batches to avoid fiber clumping.

[0018] Furthermore, in step S4, the mass ratio of the diluted water-based surface treatment agent to water is 1:1 to 1:2, and the spraying dosage per unit area is 200 to 300 g / m². 2 It does not clog the permeable pores of concrete after spraying.

[0019] Furthermore, in step S5, the concrete surface should be watered at least three times a day during the curing period to keep it constantly moist, and heavy-duty vehicles are prohibited from passing through during the curing period.

[0020] Furthermore, the high-efficiency water-reducing agent mentioned in S3 is selected from one or more of the following: polycarboxylate high-efficiency water-reducing agents, naphthalene sulfonate formaldehyde condensate, sulfonated melamine formaldehyde condensate, aliphatic hydroxysulfonate high-efficiency water-reducing agents, and aminosulfonate high-efficiency water-reducing agents.

[0021] The beneficial effects of this invention are: This invention utilizes a high-dosage composite mineral admixture to densify the internal pore structure, combined with the barrier effect of surface additives, thereby reducing the chloride ion permeability coefficient. This allows for long-term resistance to coastal salt spray and underground chloride ion erosion, preventing salt corrosion cracking and aggregate loss, extending the service life of the pavement, and filling the performance gap of existing permeable concrete for the salt-eroded environment of coastal villages. Furthermore, this invention employs a dual-fiber synergistic toughening system to enhance the flexural strength of the concrete and significantly improve its impact resistance, enabling it to withstand repeated rolling by agricultural trucks and tractors, greatly reducing pavement breakage and surface sanding damage, thus meeting the needs of rural production and traffic. This invention abandons the traditional approach of reducing pore size to prevent clogging, instead using surface hydrophobic self-cleaning modification to reduce contaminant adhesion and intrusion at the source. It retains the high permeability of large pores while achieving rainwater self-cleaning, reducing subsequent pavement maintenance costs and adapting to the limited cleaning conditions in rural areas. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to specific embodiments. The following embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it.

[0023] 1. Standard for experimental materials Portland cement: P.O 42.5 grade ordinary Portland cement; Graded crushed stone aggregate: 5~10mm continuously graded granite crushed stone, with a moisture content of 1.5% after pretreatment. Mineral admixtures: Grade I fly ash, S95 grade granulated blast furnace slag powder; Fibers: Coarse polypropylene fibers, 19mm in length, tensile strength 420MPa; fine steel fibers, 13mm in length, 0.2mm in diameter, tensile strength 2850MPa. Surface modifying agent: water-based silicone acrylic emulsion, nano silica, and white corundum micro powder are compounded in a mass ratio of 30:3:3; High-efficiency water-reducing agent: Polycarboxylate-based high-efficiency water-reducing agent, water reduction rate 25%; Mixing water: municipal tap water.

[0024] 2. Testing Methods The 28-day compressive / flexural strength was tested using the "Standard Test Methods for Physical and Mechanical Properties of Concrete"; the permeability coefficient was tested using the "Technical Specification for Permeable Cement Concrete Pavement"; the chloride ion diffusion coefficient was tested using the RCM rapid chloride ion migration method; the salt corrosion strength loss rate was tested after 30 cycles of wet and dry treatment with 3.5% NaCl solution; the surface water contact angle was tested using a contact angle measuring instrument to measure the static water contact angle of the sample surface; the permeability coefficient retention rate was measured by using a surface coated with municipal sludge to simulate blockage, and the ratio of the permeability coefficient to the initial value after 10 rainwater washes; the number of initial impact cracks was recorded using a drop hammer impact test with a 5kg drop hammer at a drop distance of 300mm.

[0025] 3. Examples and Comparative Examples

[0026] Example 1 The salt-resistant high-performance permeable concrete of this embodiment, by mass parts, has the following raw material components: 300 parts silicate cement; 1500 parts graded crushed stone aggregate; 90 parts composite mineral admixture, of which fly ash and slag powder are compounded in a 1:1 mass ratio; 3.9 parts dual-fiber compound system, of which polypropylene coarse fiber and micro steel fiber are compounded in a 1:3 mass ratio; 16 parts water-based surface treatment agent, which is compounded from water-based silicone acrylic emulsion, nano silica, and white corundum micro powder in a 30:3:3 mass ratio and does not contain organic solvents; 4.0 parts polycarboxylate-based high-efficiency water-reducing agent; 115 parts mixing water.

[0027] The preparation method of this embodiment includes the following steps: S1 Aggregate Pretreatment: 5~10mm continuous graded crushed stone is graded and screened, rinsed with clean water to remove surface mud and powder, and naturally dried until the aggregate moisture content is 1.5% for later use; S2 Dry Premix: Silicate cement, composite mineral admixture, and dual-fiber compound system are all put into a forced mixer. The fibers are dispersed by feeding them in batches and dry-mixed for 105 seconds to ensure that the fibers are evenly dispersed and do not agglomerate. S3 Wet Mixing and Molding: Add mixing water and high-efficiency water-reducing agent and stir continuously for 60 seconds, then slowly add water-based surface treatment agent. The total wet mixing time is 200 seconds, and a uniform and stable permeable concrete mixture is obtained. S4 Simultaneous Paving and Surface Protection: After paving the mixture, lightly compact it using a plate vibrator. Before the initial setting of the concrete, evenly spray the same diluted water-based surface treatment agent at a dilution ratio of 1:1.5, with a spraying dosage of 250g / m² per unit area. 2 It does not clog the permeable pores of concrete after spraying; S5 Segmented Moisture Curing: After paving, cover with geotextile and continuously spray water for 7 days to maintain moisture. During the curing period, spray water 4 times a day to keep the concrete surface moist. Heavy vehicles are prohibited from passing during the curing period. The road will be open to traffic after the curing period is over.

[0028] Example 2 The salt-resistant high-performance permeable concrete of this embodiment, by mass parts, has the following raw material components: 280 parts silicate cement; 1450 parts graded crushed stone aggregate; 70 parts composite mineral admixture, of which fly ash and slag powder are compounded at a mass ratio of 1:0.8; 2.8 parts dual-fiber compound system, of which polypropylene coarse fiber and micro steel fiber are compounded at a mass ratio of 1:1.5; 12 parts water-based surface treatment agent, which is compounded from water-based silicone acrylic emulsion, nano silica, and silicon carbide micro powder at a mass ratio of 30:3:3, and does not contain organic solvents; 3.0 parts naphthalene sulfonate formaldehyde condensate high-efficiency water-reducing agent; 100 parts mixing water.

[0029] The preparation method of this embodiment includes the following steps: S1 Aggregate Pretreatment: 5~10mm continuous graded crushed stone is graded and screened, rinsed with clean water to remove surface mud and powder, and naturally dried until the aggregate moisture content is 1.8% for later use; S2 Dry Premix: Silicate cement, composite mineral admixture, and dual-fiber compound system are all put into a small forced mixer. The fibers are dispersed by feeding them in batches and dry-mixed for 90 seconds to ensure that the fibers are evenly dispersed and do not agglomerate. S3 Wet Mixing and Molding: Add mixing water and high-efficiency water-reducing agent and stir continuously for 60 seconds, then slowly add water-based surface treatment agent. The total wet mixing time is 180 seconds, and a uniform and stable permeable concrete mixture is obtained. S4 Simultaneous Paving and Surface Protection: After paving the mixture, lightly vibrate it with a plate vibrator. Before the initial setting of the concrete, evenly spray the diluted water-based surface treatment agent of the same type. The dilution ratio is 1:1, and the spraying dosage per unit area is 200g / m². 2 It does not clog the permeable pores of concrete after spraying; S5 Segmented Moisture Curing: After paving, cover with geotextile and continuously spray water for 7 days to maintain moisture. During the curing period, spray water 3 times a day to keep the concrete surface moist. Heavy vehicles are prohibited from passing during the curing period. The road will be open to traffic after the curing period is over.

[0030] Example 3 The salt-resistant high-performance permeable concrete of this embodiment, by mass parts, has the following raw material components: 330 parts silicate cement; 1550 parts graded crushed stone aggregate; 110 parts composite mineral admixture, of which fly ash and slag powder are compounded at a mass ratio of 1:1.1; 5.0 parts dual-fiber compound system, of which polypropylene coarse fiber and micro steel fiber are compounded at a mass ratio of 1:4.5; 20 parts water-based surface treatment agent, which is composed of water-based silicone acrylic emulsion, nano silica, white corundum micro powder and silicon carbide micro powder mixed at a mass ratio of 1:1, and inorganic wear-resistant filler compounded at a mass ratio of 30:3:3, without organic solvents; 5.0 parts aliphatic hydroxysulfonate high-efficiency water-reducing agent; 130 parts mixing water.

[0031] The preparation method of this embodiment includes the following steps: S1 Aggregate Pretreatment: 5~10mm continuously graded crushed stone is graded and screened, rinsed with clean water to remove surface mud and powder, and naturally dried until the aggregate moisture content is 1.2% for later use; S2 Dry Premix: Silicate cement, composite mineral admixture, and dual-fiber compound system are all put into a forced mixer. The fibers are dispersed by feeding them in batches and dry-mixed for 120 seconds to ensure that the fibers are evenly dispersed and do not agglomerate. S3 Wet Mixing and Molding: Add mixing water and high-efficiency water-reducing agent and stir continuously for 60 seconds, then slowly add water-based surface treatment agent. The total wet mixing time is 220 seconds, and a uniform and stable permeable concrete mixture is obtained. S4 Simultaneous Paving and Surface Protection: After paving the mixture, lightly vibrate it with a plate vibrator. Before the initial setting of the concrete, evenly spray the diluted water-based surface treatment agent of the same type. The mass ratio of the diluted water-based surface treatment agent to water is 1:2, and the spraying dosage per unit area is 300g / m². 2 It does not clog the permeable pores of concrete after spraying; S5 Segmented Moisture Curing: After paving, cover with geotextile and continuously spray water for 7 days to maintain moisture. In low-temperature environments, cover with an insulation film. Spray water 4 times a day during the curing period to keep the concrete surface moist. Heavy-duty vehicles are prohibited from passing during the curing period. The road will be open to traffic after the curing period is over.

[0032] Comparative Example 1 Compared with Example 1, only 90 parts of fly ash were used, and no slag powder was used; the remaining components were completely the same as those in Example 1.

[0033] Comparative Example 2 Compared to Example 1, only 3.9 parts of fine steel fiber were used, with no coarse polypropylene fiber; the remaining components were completely identical to those in Example 1.

[0034] Comparative Example 3 Compared with Example 1, no water-based surface treatment agent is added in S3, and the S4 spraying process is omitted; the remaining components are completely the same as in Example 1.

[0035] Comparative Example 4 Compared with Example 1, the S3 internal additive is retained, and only the S4 spraying process is omitted; the remaining components are completely the same as in Example 1.

[0036] Comparative Example 5 Compared with Example 1, the ratio of fly ash to slag is 1:1.5; the rest is completely the same as Example 1.

[0037] Comparative Example 6 Compared with Example 1, the polypropylene coarse fiber and micro steel fiber were compounded at a mass ratio of 1:0.5, and the rest was completely the same as Example 1.

[0038] 4. Summary of Experimental Data

[0039] 5. Experimental Data Analysis Based on the experimental data above, it can be seen that, in Comparative Example 1, which uses only a single component of fly ash, the chloride ion diffusion coefficient increases to 4.8 × 10⁻⁶. -12 m 2 / s, the salt corrosion intensity loss rate reached 9.5%, which is 128.6% and 126.2% higher than that of Example 1, respectively. The reason is that the reaction rate of fly ash and pozzolanic material alone is slow, and the early pore refinement ability is insufficient, so it cannot effectively block the chloride ion penetration channel; while the highly active component of slag powder in Example 1 can quickly consume calcium hydroxide, and work with the secondary hydration of fly ash to fill the capillary pores, forming a gradient protection of early chloride inhibition and long-term denseness, which significantly reduces the chloride ion penetration rate.

[0040] Comparative Example 5, where the ratio of fly ash to slag powder was adjusted to 1:1.5, increased its chloride ion diffusion coefficient to 3.2 × 10⁻⁶. -12 m 2 / s, the salt corrosion loss rate rose to 6.7%, which was worse than Example 1. The reason is that the excessive slag powder caused the slurry viscosity to rise sharply, the uneven fiber dispersion produced internal micro-defects, and chloride ions penetrated rapidly along the defect path; at the same time, the increased heat of hydration easily caused thermal shrinkage micro-cracks, further weakening the salt corrosion resistance.

[0041] Comparative Example 2 used only a single type of fine steel fiber, with the same total fiber content as Example 1. However, the flexural strength decreased to 4.47 MPa, and the number of initial impact cracks was only 78, representing a decrease of 14.2% and 35.5% respectively compared to Example 1. This is because the lack of polypropylene coarse fiber inhibits early plastic shrinkage cracking. During the concrete forming and curing stage, a large number of microcracks emerge on the surface. Although steel fibers can improve the rigidity of the matrix, they cannot compensate for the original micro-defects. Under stress, the cracks propagate rapidly along the microcracks, ultimately resulting in a significant decrease in flexural and impact resistance.

[0042] Comparative Example 6 reduced the steel fiber ratio to 1:0.5, resulting in a flexural strength of 4.12 MPa and only 69 initial impact cracks, representing decreases of 20.9% and 43.0% respectively compared to Example 1. This is because insufficient steel fiber content prevents the formation of a complete three-dimensional rigid toughening skeleton within the matrix, significantly weakening its ability to resist macroscopic crack propagation and making it unsuitable for withstanding repeated crushing by heavy agricultural machinery. In Examples 1-3, within the specified ratio range, flexural strength and impact performance steadily increased with increasing steel fiber ratio, while the permeability coefficient did not show a significant decrease. This demonstrates that the compound range achieved layered synergistic toughening through surface micro-crack control and internal macro-crack prevention, balancing mechanical load-bearing capacity and permeability.

[0043] Comparative Example 3 completely eliminated internal additives and surface coating, resulting in a surface water contact angle of only 68°, indicating a hydrophilic state. The water permeability retention rate plummeted to 58.1%, while the chloride ion diffusion coefficient increased to 3.8 × 10⁻⁶. -12 m 2 / s. This indicates that without a hydrophobic surface structure, sludge easily adheres and seeps into the surface pores, causing blockage, and chloride ions can directly penetrate the interior through the surface capillaries, resulting in decreased salt corrosion resistance.

[0044] Comparative Example 4, retaining the internal additives but omitting surface spraying, achieved a water contact angle of 89° and a water permeability retention rate of 72.4%, demonstrating better salt corrosion resistance than Comparative Example 3, but still significantly lower than Example 1. This is because the internal additives can only fill some capillaries within the matrix, and the small amount of components migrating to the surface cannot form a continuous and complete hydrophobic protective film. Surface spraying, on the other hand, can construct a continuous micro-nano hydrophobic structure on the surface, achieving both rainwater self-cleaning and anti-clogging, and forming the first chloride ion barrier. Together with the internal additives and mineral admixtures, it constitutes an externally sealed and internally blocked salt corrosion resistant system.

[0045] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A high-performance permeable concrete suitable for salt corrosion resistance, characterized in that, By mass, it includes the following raw material components: 280-330 parts of silicate cement; Graded crushed stone aggregate: 1450–1550 parts; 70-110 parts of composite mineral admixture; The dual-fiber compound system comprises 2.8–5.0 parts; 12-20 parts of water-based surface treatment agent; High-efficiency water-reducing agent, 3.0–5.0 parts; Mix with 100-130 parts of water.

2. The salt-resistant, high-performance permeable concrete according to claim 1, characterized in that, The composite mineral admixture is made by mixing fly ash and slag powder in a mass ratio of 1:0.8 to 1.

1.

3. The salt-resistant, high-performance permeable concrete according to claim 1, characterized in that, The dual-fiber composite system is composed of polypropylene coarse fibers and micro-fine steel fibers in a mass ratio of 1:1.5 to 4.

5.

4. The salt-resistant, high-performance permeable concrete according to claim 1, characterized in that, The water-based surface treatment agent is composed of water-based silicone-acrylic emulsion, nano-silica, and inorganic wear-resistant filler, and does not contain organic solvents; the mass ratio of water-based silicone-acrylic emulsion, nano-silica, and inorganic wear-resistant filler is 30:3:3; the inorganic wear-resistant filler is white corundum micro powder and / or silicon carbide micro powder.

5. The salt-resistant, high-performance permeable concrete according to claim 1, characterized in that, The graded crushed stone aggregate is continuously graded crushed stone after grading and screening, and the moisture content of the aggregate is ≤2% after pretreatment.

6. A method for preparing salt-resistant, high-performance permeable concrete as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1 Aggregate Pretreatment: Gradually screen the crushed stone aggregate, rinse with clean water to remove surface mud and powder, and air dry naturally until the aggregate moisture content is ≤2% for later use; S2 Dry premix: Put silicate cement, composite mineral admixture, and dual fiber compound system into a forced mixer and dry mix for 90-120 seconds to ensure that the fibers are evenly dispersed and do not agglomerate. S3 Wet Mixing and Molding: Add mixing water and high-efficiency water-reducing agent and stir continuously for 60 seconds, then slowly add water-based surface treatment agent. The total wet mixing time is ≥180 seconds to obtain a uniform and stable permeable concrete mixture. S4 Simultaneous protection during paving and surface treatment: After paving the mixture, use a plate vibrator to lightly vibrate it, and spray the diluted water-based surface treatment agent of the same type evenly before the initial setting of the concrete. S5 Segmented Moisture Retention and Maintenance: After paving, cover with geotextile and continuously spray water for 7 days to maintain moisture retention. In low-temperature environments, cover with an insulation film. After the maintenance period, the road can be opened to traffic.

7. The preparation method according to claim 6, characterized in that, In step S2, a small forced mixer is used for dry mixing. During the dry mixing process, the fibers are dispersed by feeding them in batches to avoid fiber clumping.

8. The preparation method according to claim 6, characterized in that, In step S4, the mass ratio of the diluted water-based surface treatment agent to water is 1:1 to 1:2, and the spraying dosage per unit area is 200 to 300 g / m². 2 It does not clog the permeable pores of concrete after spraying.

9. The preparation method according to claim 6, characterized in that, In step S5, water should be sprayed no less than 3 times a day during the curing period to keep the concrete surface moist. Heavy-duty vehicles are prohibited from passing through during the curing period.

10. The preparation method according to claim 6, characterized in that, The high-efficiency water-reducing agent mentioned in step S3 is selected from one or more of the following: polycarboxylate high-efficiency water-reducing agents, naphthalene sulfonate formaldehyde condensate, sulfonated melamine formaldehyde condensate, aliphatic hydroxysulfonate high-efficiency water-reducing agents, and aminosulfonate high-efficiency water-reducing agents.

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