Heavy-load pervious concrete road surface material and preparation method thereof

Abstract

The application discloses a kind of heavy load water-permeable concrete road surface layer material and preparation method thereof, belong to road engineering material technical field.The material is composed of specific proportion hard counter-break stone, Portland cement, full inorganic composite functional cementitious agent and mixing water, composite functional cementitious agent is compounded by inorganic water reducing agent, inorganic early strength agent, inorganic water retaining agent, the cement reinforcing effect is realized by the synergy of three, material initial setting time can be accurately controlled at about 2 hours, with excellent water permeability, bearing capacity and weather resistance and anti-aging performance, the design service life of prepared road surface layer can reach 15-20 years, solve the technical problems of traditional water-permeable concrete insufficient strength, organic additive easy aging, poor road durability.The material formula of the application is scientific and reasonable, preparation process is simple, production cost is controllable, suitable for heavy load traffic road surface layer laying, with good popularization and application prospect.

Description

Technical Field

[0001] This invention relates to the field of road engineering materials technology, and in particular to a heavy-duty permeable concrete road surface material and its preparation method. Background Technology

[0002] Permeable concrete, also known as porous concrete or drainage concrete, is a type of porous lightweight concrete made from aggregates, cement, and water. It is characterized by its air permeability, water permeability, and light weight, and is widely used in projects such as sidewalks and non-motorized vehicle lanes in sponge city construction.

[0003] Traditional permeable concrete is permeable concrete with added organic additives. This type of material has certain advantages: First, organic additives (such as redispersible latex powder and naphthalene-based water-reducing agents) can improve the cohesiveness and fluidity of cement paste, reduce aggregate segregation, and make paving and vibration construction smoother; Second, organic polymer components can form a flexible film at the interface between cement paste and aggregate, improving the material's early crack resistance and flexural strength compared to pure inorganic permeable concrete; Third, there is a wide variety of organic additives that can be compounded as needed, allowing for rapid adaptation to different aggregates and construction environments, and the technology is highly mature. However, this type of material has two major drawbacks: First, its strength is relatively low. Its structural framework relies on point contact between aggregates and cement paste bonding. Even if the 28-day compressive strength can be increased to about 25 MPa through formula optimization, it is still difficult to withstand the long-term rolling of heavy vehicles, and it is prone to surface damage, cracking, collapse, and other defects. Second, its weather resistance is extremely poor. The organic components are prone to degradation and pulverization under natural environments such as sunlight, rain, and high and low temperature cycles, leading to a rapid decline in material strength. After 25 freeze-thaw cycles, the strength reduction rate can reach 20%. Under ideal laboratory conditions, the designed service life is 5-8 years. In actual engineering, due to the influence of heavy rolling, extreme temperature and humidity, and ultraviolet radiation, the actual service life is generally only 2-3 years, which significantly increases the cost of road resurfacing. At the same time, the organic components are prone to softening and decomposition at high temperatures, and their high-temperature stability is insufficient, making them unsuitable for heavy-load road scenarios exposed to high temperatures and sunlight. In addition, the production of some organic additives is highly polluting and expensive, and they are difficult to degrade naturally after disposal, posing potential risks to environmental protection and cost.

[0004] To address the aforementioned technical shortcomings of traditional permeable concrete, the development of permeable concrete materials that combine high permeability, high load-bearing strength, and high weather resistance and durability has become a key research focus in the field of road engineering. By employing a fully inorganic additive system, the problem of organic component aging can be fundamentally solved. Simultaneously, optimizing aggregate types, particle sizes, and cementitious system proportions can effectively improve the mechanical properties of permeable concrete, enabling it to meet the requirements of heavy-duty roads. Summary of the Invention

[0005] This invention provides a heavy-duty permeable concrete road surface material and its preparation method to solve the technical defects of traditional permeable concrete, such as insufficient strength, easy aging of organic additives, and poor road durability.

[0006] This application provides a heavy-duty permeable concrete road surface material, which, by weight, comprises: 1600 parts of hard impact crushed stone, 400 parts of silicate cement, 10 parts of all-inorganic composite functional cementitious agent, and an appropriate amount of mixing water (water-cement ratio 1:0.3-0.33).

[0007] The hard impact crusher aggregate is preferably made of basalt or granite, and secondarily limestone. The aggregate size is 3-12mm (5-12mm for the bottom layer and 3-5mm for the surface layer), the crushing value is ≤10%, the content of needle-like and flaky particles (by mass) is ≤10%, the mud content is ≤1%, the sand content is ≤10%, the apparent density is ≥2500kg / m³, the compacted bulk density is ≥1350kg / m³, and the porosity is ≤47%.

[0008] The silicate cement used is selected as P·O42.5 or P·O52.5 according to the compressive strength requirements of the road surface.

[0009] The aforementioned inorganic composite functional cementitious agent is a composite high-concentration functional solution type, with a total weight of 10 parts. It is composed of 3 parts of inorganic water-reducing agent high-concentration functional solution, 6 parts of inorganic early-strength agent high-concentration functional solution, and 1 part of inorganic water-retaining agent colloidal dispersion. All components are stable systems at 20°C. The three types of components work synergistically to achieve cement strengthening effect. There is no independent cement strengthening agent component. Its specific functions are as follows: 1. Inorganic water-reducing agent: High-concentration functional solution of anhydrous sodium sulfate is selected, which can be adsorbed on the surface of cement particles, reduce the attraction between particles, reduce the amount of mixing water, optimize the fluidity of cement paste, and improve the density and compressive strength of concrete. 2. Inorganic early strength agent: High-concentration functional solution of calcium nitrate is selected, which can accelerate the cement hydration reaction rate, generate more hydration products, shorten the setting time, and accurately control the initial setting time of the material to about 2 hours, which is suitable for the construction rhythm. 3. Inorganic water-retaining agent: 325-mesh dense silica fume colloidal dispersion is selected. It relies on micro-nano particle size and high specific surface area to adsorb water, avoid surface cracking caused by excessive water evaporation, ensure full hydration of cement, and improve material durability and later strength.

[0010] The preparation of 3 parts of high-concentration functional solution of inorganic water-reducing agent is as follows: Take about 0.90 parts of anhydrous sodium sulfate and dissolve it in about 2.10 parts of water to prepare a stable high-concentration solution.

[0011] The preparation of 6 parts of high-concentration functional solution of inorganic early strength agent is as follows: Take about 3.54 parts of calcium nitrate and dissolve it in about 2.46 parts of water to prepare a stable high-concentration solution.

[0012] The preparation of 1 part of inorganic water-retaining agent colloidal dispersion is as follows: Take 1.0 part of 325 mesh dense silica fume, add it to the mixed solution and disperse it at high speed to form a stable colloidal dispersion.

[0013] The three components, when combined, form a stable composite solution system that synergistically exerts four major effects: water reduction, early strength, water retention, and reinforcement. This fundamentally solves the problem of easy aging of traditional organic additives, while significantly improving the load-bearing capacity and weather resistance of permeable concrete.

[0014] The amount of mixing water added should be based on the workability of the concrete and should be flexibly adjusted according to the actual construction environment temperature and humidity to ensure that the mixture has good paving and vibration performance and that the initial setting time is stable at about 2 hours.

[0015] The inorganic water-reducing agent is one or two of anhydrous sodium sulfate, sodium hexametaphosphate, and sodium tripolyphosphate; the inorganic early-strength agent is one or two of calcium nitrate, lithium carbonate, and anhydrous sodium sulfate; and the inorganic water-retaining agent is one of silica fume, bentonite, attapulgite, or zeolite powder.

[0016] The amount of mixing water added is based on meeting the workability requirements of the concrete, and the initial setting time of the material is precisely controlled at around 2 hours.

[0017] This invention also discloses a method for preparing the heavy-duty permeable concrete road surface material, comprising the following steps: 1. Raw material pretreatment: Select hard impact crusher stones that meet the requirements according to claim 1, and set them aside for later use.

[0018] 2. Preparation of gelling agent: Prepare high-concentration functional solutions of inorganic water-reducing agent, inorganic early-strength agent, and inorganic water-retaining agent colloidal dispersions according to the specified ratios. Then, thoroughly mix the three components to obtain a uniform, sediment-free, all-inorganic composite functional gelling agent.

[0019] 3. Dry mixing: Add the prepared hard impact crushed stone and silicate cement into a forced mixer according to the proportion, and dry mix at a speed of 120-150 r / min for 2-3 minutes to ensure that the aggregate and cement are mixed evenly.

[0020] 4. Wet mixing: Mix water and inorganic composite functional binder thoroughly at a water-cement ratio of 1:0.3 to 0.33, then add the mixture to the dry mix. Keep the mixer speed constant and continue mixing for 2 to 3 minutes until a homogeneous, lump-free permeable concrete mixture with a slump of 10 to 50 mm is formed.

[0021] 5. Molding and Curing: Spread the mixture on the prepared construction base surface in a timely manner, and vibrate it with a plate vibrator for 30-60 seconds. Avoid over-vibration during the vibration process to prevent aggregate segregation. After vibration, level the surface. If layered construction is required, continue the above steps and then spread the surface layer. After spreading, cover with a film to retain moisture and cure for no less than 24 hours. Remove the film after 24 hours and allow it to cure in the open air for no less than 28 days. Once the strength reaches the relevant national standards for heavy-duty roads, the road can be opened to traffic.

[0022] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses hard impact crushed stone as aggregate, combined with silicate cement and an inorganic composite functional binder. The formula is scientific and reasonable, and the permeable concrete prepared not only has high porosity and excellent permeability, but also has excellent compressive strength and wear resistance. It can withstand the long-term rolling of heavy vehicles and is suitable for heavy-duty road surface layers.

[0023] 2. The core innovation of this invention lies in the use of a precisely proportioned all-inorganic composite functional binder, which is composed of water-reducing agent, early-strength agent and water-retaining agent. It works synergistically to achieve a strengthening effect, completely eliminates organic additives, fundamentally solves the problem of easy aging of organic components in traditional permeable concrete, greatly improves the weather resistance and anti-aging ability of the material, and significantly extends the service life of the road.

[0024] 3. This invention precisely controls the initial setting time of materials to about 2 hours by adjusting the early strength agent in the inorganic binder, which is suitable for the construction period requirements of road construction, shortens the construction waiting time, and improves construction efficiency.

[0025] 4. The preparation method of the present invention is simple and easy to implement, requires no special equipment, has controllable production costs, is suitable for large-scale industrial production and on-site construction, and has broad application value.

[0026] 5. Long service life: The all-inorganic system of this invention has no risk of aging and degradation. Combined with high compressive strength and low weathering attenuation rate, the heavy-duty permeable concrete road surface layer prepared can have a design service life of 15-20 years. In contrast, the service life of traditional organic additive permeable concrete road surface layers is 5-8 years under ideal laboratory conditions, and generally only 2-3 years in actual engineering. The road service life of the material of this invention is significantly extended, which can greatly reduce the later maintenance costs. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the preparation process of the heavy-duty permeable concrete road surface material of the present invention. Detailed Implementation

[0028] Various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0029] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0030] Example 1: A heavy-duty permeable concrete road surface material, by weight, the raw materials are: 1600 parts of basalt gravel with a particle size of 8-10mm and a moisture content of 0.8%, 400 parts of P·O52.5 silicate cement, 10 parts of all-inorganic composite functional cementitious agent, and 120 parts of mixing water.

[0031] Preparation of the all-inorganic composite functional gelling agent (at 20°C): 1. Saturated solution of inorganic water-reducing agent (3 parts): Dissolve about 0.90 parts of anhydrous sodium sulfate in about 2.10 parts of water to prepare a stable saturated solution; 2. Saturated solution of inorganic early strength agent (6 parts): Dissolve about 3.54 parts of calcium nitrate in about 2.46 parts of water to prepare a stable saturated solution; 3. Inorganic water-retaining agent colloidal dispersion (1 part): Take 1.0 part of 325 mesh dense silica fume, add it to the mixed solution and disperse it at high speed to form a stable colloid; 4. Mixing: Thoroughly mix the above three components to obtain 10 parts of uniform, sediment-free composite functional binder. The three components work synergistically to achieve the effects of promoting cement hydration, optimizing paste, and improving strength.

[0032] Its preparation method includes the following steps: (1) Raw material pretreatment: Screen basalt stones that meet the requirements of particle size and moisture content, and remove impurities for later use; (2) Dry mixing: Add basalt gravel and P·O42.5 silicate cement to the mixer and dry mix at 130r / min for 2.5min; (3) Wet mixing: Add 10 parts of all-inorganic composite functional cementitious agent and 120 parts of mixing water, stir at 130r / min for 2min to obtain permeable concrete mixture; (4) Molding and curing: Spread the mixture, vibrate it with a plate vibrator for 45 seconds, level it, cover it with a film for curing, and cure it for no less than 24 hours. After 24 hours, remove the film and cure it in the open air for 28 days to obtain the finished product.

[0033] The finished product has a permeability coefficient of 0.762 mm / s, a 28-day compressive strength of 51.4 MPa, an initial setting time of 1 hour and 55 minutes, and weather resistance tests show that after 25 freeze-thaw tests, the strength attenuation rate is less than 10%, which is far lower than the 20% strength attenuation rate of traditional organic additive permeable concrete.

[0034] Example 2: A heavy-duty permeable concrete road surface material, by weight, the raw materials are: 1600 parts of basalt gravel with a particle size of 8-10mm, 400 parts of P·O 42.5 silicate cement, 10 parts of all-inorganic composite functional cementitious agent, and 125 parts of mixing water.

[0035] Preparation of the all-inorganic composite functional gelling agent (at 20°C): 1. Saturated solution of inorganic water-reducing agent (4 parts): Dissolve about 0.18g of sodium tripolyphosphate in 3.82g of water to prepare a stable saturated solution; 2. Saturated solution of inorganic early strength agent (4 parts): Dissolve about 1.63g of sodium sulfate in 2.37g of water to prepare a stable saturated solution; 3. Inorganic water-retaining agent colloidal dispersion (2 parts): Take 0.4g of 300-mesh bentonite, add 1.6g of water and stir at high speed to disperse into a uniform colloid; 4. Mixing: Thoroughly mix the above three components to obtain 10 parts of uniform, non-precipitated composite functional gelling agent.

[0036] The preparation method is the same as in Example 1.

[0037] The finished product was tested and found to have a permeability coefficient of 11 mm / s, a 28-day compressive strength of 40 MPa, an initial setting time of 2 hours and 5 minutes, and a strength decay rate of less than 10% after 25 freeze-thaw tests.

[0038] Example 3: A heavy-duty permeable concrete road surface material, the raw materials by weight are: 1600 parts of basalt gravel with a particle size of 8-10mm and a moisture content of 0.7%, 400 parts of P·O42.5 silicate cement, 10 parts of all-inorganic composite functional cementitious agent, and 130 parts of mixing water.

[0039] Preparation of the all-inorganic composite functional gelling agent (at 20°C): 1. Saturated solution of inorganic water-reducing agent (4 parts): Take 0.08g sodium hexametaphosphate + 0.05g sodium carbonate, dissolve in 3.87g water, and prepare a stable mixed saturated solution; 2. Saturated solution of inorganic early strength agent (4 parts): Dissolve about 1.63g of sodium sulfate in 2.37g of water to prepare a stable saturated solution; 3. Inorganic water-retaining agent colloidal dispersion (2 parts): Take 0.4g of 300-mesh zeolite powder, add 1.6g of water and stir at high speed to disperse into a uniform colloid; 4. Mixing: Thoroughly mix the above three components to obtain 10 parts of uniform, non-precipitated composite functional gelling agent.

[0040] The preparation method is the same as in Example 1.

[0041] The finished product was tested and found to have a permeability coefficient of 11.5 mm / s, a 28-day compressive strength of 41 MPa, an initial setting time of 2 hours and 5 minutes, and a strength decay rate of less than 10% after 25 freeze-thaw tests.

[0042] Performance Comparison Analysis To further verify the superiority of the material of the present invention, the heavy-duty permeable concrete prepared in Example 1 of the present invention was compared with the performance of conventional organic additive permeable concrete and ordinary basalt permeable concrete by means of conventional process formulation.

[0043] Conventional organic additive permeable concrete formula: 1600 parts by weight of basalt gravel (8-10mm), 400 parts by weight of 425# silicate cement, 15 parts by weight of EVA redispersible latex powder, 3 parts by weight of naphthalene-based water-reducing agent, and 80 parts by weight of mixing water. The preparation process has no special optimization. The test results are shown in the table below: Table 1 Concrete Test Results Data , Note: The freeze-thaw resistance test consists of a low-temperature freezing (-20℃, 4h) + thawing (20℃, 4h) cycle, for a total of 25 cycles, 200h, continuous testing, in accordance with GB / T50082-2009; the service life calculation is based on the correlation model between the weathering cycle strength attenuation rate and the actual service life of the road, in accordance with the "Code for Construction and Quality Acceptance of Urban Road Engineering" CJJ 1-2008.

[0044] Explanation of the necessity of comparison: Setting up two control groups establishes a performance gradient from "organic modified permeable concrete → the all-inorganic functional modified permeable concrete of this invention." This invention, through the synergistic effect of an all-inorganic composite functional binder, significantly improves the early strength, 28-day compressive strength, and freeze-thaw durability of permeable concrete while ensuring high permeability. Initial setting time is controllable, there is no risk of aging or shedding of organic components, and the service life is greatly extended, meeting the long-term stable service requirements of heavy-duty traffic road surfaces. This clearly highlights the significant advantages of the material in core indicators such as strength, durability, and service life, enhancing the persuasiveness of the patented technical solution.

[0045] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A heavy-duty permeable concrete road surface material, characterized in that, By weight, the raw material composition includes: The mixture comprises 1600 parts of hard impact crusher aggregate, 400 parts of silicate cement, 10 parts of inorganic composite functional cementitious agent, and mixing water, wherein the water-cement ratio is 1:0.3-0.33; the hard impact crusher aggregate is basalt, granite, or limestone, with a particle size of 3-12mm, a crushing value ≤10%, a needle-like and flaky particle content ≤10% by mass, a mud content ≤1%, a sand content ≤10%, an apparent density ≥2500kg / m³, a compacted bulk density ≥1350kg / m³, and a porosity ≤47%; the silicate cement is P·O 42.5 or P·O 52.5; the inorganic composite functional cementitious agent is a composite saturated solution type, composed of 3 parts of inorganic water-reducing agent saturated liquid, 6 parts of inorganic early-strength agent saturated liquid, and 1 part of inorganic water-retaining agent colloidal dispersion, with a total weight of 10 parts, and all components are stable systems at 20℃.

2. The heavy-duty permeable concrete road surface material according to claim 1, characterized in that, The inorganic water-reducing agent is one or two of anhydrous sodium sulfate, sodium hexametaphosphate, and sodium tripolyphosphate; the inorganic early-strength agent is one or two of calcium nitrate, lithium carbonate, and anhydrous sodium sulfate; and the inorganic water-retaining agent is one of silica fume, bentonite, attapulgite, or zeolite powder.

3. The heavy-duty permeable concrete road surface material according to claim 1, characterized in that, The amount of mixing water added is sufficient to achieve a concrete slump of 10-50mm, and to ensure precise control of the initial setting time of the material.

4. The heavy-duty permeable concrete road surface material according to claim 1, characterized in that, The preparation of 3 parts of high-concentration functional solution of inorganic water-reducing agent is as follows: Take about 0.90 parts of anhydrous sodium sulfate and dissolve it in 2.10 parts of water to prepare a stable high-concentration solution.

5. The heavy-duty permeable concrete road surface material according to claim 1, characterized in that, The preparation of 6 parts of high-concentration functional solution of inorganic early strength agent is as follows: take 3.54 parts of calcium nitrate and dissolve it in 2.46 parts of water to prepare a stable high-concentration solution.

6. The heavy-duty permeable concrete road surface material according to claim 1, characterized in that, The preparation of 1 part of inorganic water-retaining agent is as follows: Take 1.0 part of 325 mesh dense silica fume, add it to the mixture of high concentration functional solution of water-reducing agent and high concentration functional solution of early strength agent, and disperse it at high speed to form a stable colloidal dispersion.

7. A method for preparing a heavy-duty permeable concrete road surface material, characterized in that, The method is used to prepare the pavement layer material according to any one of claims 1-6, and the method includes the following steps: (1) Raw material pretreatment: Screen hard impact crusher stones for later use; (2) Preparation of gelling agent: Prepare high-concentration functional solution of inorganic water-reducing agent, high-concentration functional solution of inorganic early strength agent and inorganic water-retaining agent according to the ratio, and then mix the three components thoroughly to obtain an all-inorganic composite functional gelling agent; (3) Dry mixing: Put the prepared hard impact crusher stones and silicate cement into the mixer and dry mix for 2-3 minutes to obtain dry mix; (4) Wet mixing: Mix water and inorganic composite functional binder thoroughly at a water-cement ratio of 1:0.3 to 0.33, then add it to the dry mix and continue mixing for 2 to 3 minutes to obtain a permeable concrete mixture with a slump of 10 to 50 mm. (5) Molding and curing: Spread the permeable concrete mixture on the construction base surface and vibrate it to form the shape. If layered construction is required, continue the above steps for paving. After paving, use a film to keep it moist and cure for no less than 24 hours. Remove the film after 24 hours and cure in the open air for 28 days to obtain the heavy-duty permeable concrete road surface.

8. The method for preparing a heavy-duty permeable concrete road surface material according to claim 7, characterized in that, The stirring speed in steps (3) and (4) is 120-150 r / min.

9. The method for preparing a heavy-duty permeable concrete road surface material according to claim 7, characterized in that, In step (5), a flat vibrator is used for compaction, and the compaction time is 30-60 seconds to avoid over-vibration that could lead to aggregate segregation.

Images