A construction method for a permeable sidewalk based on iron-based polymer cementitious materials

Abstract

The present invention discloses a construction method for a permeable sidewalk based on an iron-based polymer cementitious material. The method comprises the following steps: firstly configuring an alkali activator for standby use; then mixing the iron-based polymer precursor powder with the alkali activator, and fully stirring to obtain a viscous iron-based polymer gel slurry; then compacting the road soil base, supporting a mold, and pouring the iron-based polymer slurry into the mold to obtain a waterproof base; then fully mixing and stirring the open-graded aggregate and the iron-based polymer gel to obtain a mixed slurry, pouring the mixed slurry into the waterproof base in the mold supported in step S3 and leveling the slurry to obtain a permeable layer; after film coating and curing, removing the mold and the film to obtain the cured iron-based polymer gel permeable layer; finally, laying the upper layer of permeable bricks and curbstones to complete the construction of the permeable sidewalk. The present invention utilizes the high strength characteristics of the iron-based polymer to prepare a permeable concrete with both high strength and high permeability; thus, the sidewalk of the present invention has good bearing capacity and anti-water accumulation capability.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste resource utilization, and in particular relates to a construction method of a permeable sidewalk based on an iron-based polymer cementitious material. Background Art

[0002] To address the threat posed to public health and safety by scrap steel and aluminum ash, research on the resource utilization of these waste materials has increased. The primary approach is to recycle the iron and aluminum from these materials as secondary metals. However, this method only utilizes a portion of the waste. For steel scrap, comprehensive utilization currently stands at only 50%, leaving a significant amount of waste material abandoned in landfills. The comprehensive utilization of aluminum ash faces a similar dilemma. Low-aluminum solid waste is primarily disposed of by landfill, a method that poses significant environmental risks. Under varying climatic conditions, toxic metal ions can leach into groundwater and produce toxic and odorous gases such as NH3, CH4, PH4, and H2S. This not only occupies significant land but also pollutes the environment. Expanding the utilization of these waste materials would not only save landfill space and mitigate the environmental pollution associated with these solid wastes, but also create significant social and economic value by transforming waste into valuable resources.

[0003] Permeable concrete, also known as porous concrete, sandless concrete, or permeable flooring, is a porous, lightweight concrete made from aggregate, cement, a reinforcing agent, and water; it contains no fine aggregate. Permeable concrete consists of a thin layer of cement slurry coated on the surface of coarse aggregate, which bonds together to form a honeycomb structure with evenly distributed pores. This structure is breathable, water-permeable, and lightweight. The most common cement in existing technology is calcium silicate cement. Because permeable concrete requires a very low cement content and forms only a thin layer on the aggregate surface, permeable concrete made with ordinary Portland cement has very limited strength and a short service life, limiting its development and use. Therefore, a material that can replace Portland cement is needed to make permeable concrete that maintains its permeability while also providing high strength. Summary of the Invention

[0004] The purpose of the present invention is to provide a construction method for a permeable sidewalk based on an iron-based polymer cementitious material in response to the problems existing in the prior art. The present invention adopts an iron-based polymer cementitious material to configure permeable concrete, which not only solves the contradiction between the strength and permeability of the permeable concrete, but also realizes the recycling of scrap steel and scrap aluminum ash, thereby achieving the purpose of protecting the environment and realizing social and economic benefits.

[0005] In order to achieve the above object, the present invention adopts the following counting scheme:

[0006] A construction method for a permeable sidewalk based on an iron-based polymer cementitious material comprises the following steps:

[0007] S1. Prepare the alkaline activator for standby use;

[0008] S2. Mixing the iron-based polymer precursor powder and the alkaline activator, and stirring thoroughly to obtain a viscous iron-based polymer gel slurry;

[0009] S3. Compact the road soil base, support the formwork, and then pour the iron-based polymer slurry into the base to form a waterproof base;

[0010] S4, the 10-25mm open-graded aggregate and the iron-based polymer gel are thoroughly mixed and stirred to obtain a mixed slurry, and the mixed slurry is poured into the waterproof base in the mold supported in step S3 and leveled to obtain a permeable layer;

[0011] S5. After film coating and curing, the mold and film are removed to obtain the cured iron-based polymer gel permeable layer.

[0012] S6. Lay the upper layer of permeable bricks and curb stones to complete the construction of the permeable sidewalk.

[0013] The present invention uses iron-based polymer precursor powder and alkali activator instead of ordinary Portland cement to prepare permeable concrete. Even if a very thin layer is formed on the aggregate surface, it can provide good bonding ability and strength, so that the iron-based polymer gel permeable layer of the present invention has both high strength and high permeability.

[0014] Preferably, in step S1, the alkaline activator is one or more of alkali metal hydroxides, alkali metal carbonates, and alkali metal silicates.

[0015] Preferably, in step S1, the concentration of the base activator is 6 to 8 mol / L.

[0016] Preferably, the alkaline activator is composed of a mixture of sodium silicate and alkali metal hydroxide.

[0017] Alkali metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, francium hydroxide, etc.; alkali metal carbonates include sodium carbonate, potassium carbonate, sodium bicarbonate, disodium bicarbonate, potassium bicarbonate, dipotassium bicarbonate, etc.; alkali metal silicates include lithium silicate, sodium silicate, potassium silicate, rubidium silicate, cesium silicate, francium silicate, etc.

[0018] Preferably, in step S2, the iron-based polymer precursor and the alkaline activator are mixed at a water-to-binder ratio of 0.5 to 0.6;

[0019] Preferably, in step S3, the thickness of the waterproof base layer is 3-6 cm, and a slope of 1% to 2% is set in the longitudinal direction.

[0020] Preferably, in step S4, the mixing ratio of the open-graded aggregate to the iron-based polymer gel is 5 to 9:3, preferably 7:3, and the thickness of the permeable layer is not less than 20 cm.

[0021] Preferably, in step S4, crushed stone with a particle size of about 15 mm to 25 mm is selected as the open-graded aggregate in the mixed slurry.

[0022] Preferably, in the iron-based polymer gel slurry of step S2, the mass fractions of the components are as follows:

[0023] 40-60 parts of scrap aluminum ash

[0024] 10-30 pieces of scrap steel

[0025] 60-90 parts of ethyl silicate

[0026] 8-10 parts of alkali activator

[0027] Preferably, the aluminum ash is aluminum-containing waste generated in aluminum industry production.

[0028] Preferably, the scrap steel mainly comes from self-produced scrap steel, processed scrap steel, depreciated scrap steel, and imported scrap steel.

[0029] Preferably, the ethyl silicate is tetraethyl silicate produced in common industry.

[0030] The present invention also provides a method for preparing the above-mentioned iron-based polymer precursor powder, comprising the following steps:

[0031] (1) Crushing and grinding scrap iron and aluminum ash to obtain scrap iron powder and scrap aluminum ash powder;

[0032] (2) using an organic acid to dissolve the scrap iron powder and the scrap aluminum ash powder respectively to obtain a scrap iron organic acid solution and a scrap aluminum organic acid solution, and mixing them to obtain an iron-aluminum mixed solution;

[0033] (3) dissolving ethyl silicate in a water-soluble organic solvent to obtain an ethyl silicate solution;

[0034] (4) mixing the iron-aluminum mixed solution obtained in step (1) and the ethyl silicate solution obtained in step (2) and stirring them uniformly to obtain an Al-Fe-Si mixed system;

[0035] (5) heating the Al-Fe-Si mixed system in a water bath to perform a gel reaction to obtain a gel system, and drying the gel system to a constant weight;

[0036] (6) The dried gel system is calcined in a muffle furnace and then ball-milled into powder to obtain a highly active iron-based polymer precursor powder.

[0037] Preferably, the waste iron slag and waste aluminum ash in step (1) should be finely ground to below 100 mesh.

[0038] Preferably, in step (2), the organic acid for dissolving the waste iron powder includes salicylic acid, benzoic acid, etc., and the organic acid for dissolving the waste aluminum ash powder includes citric acid, benzoic acid, etc.

[0039] The present invention uses salicylic acid and citric acid to dissolve waste iron slag and waste aluminum ash respectively. On the one hand, it can utilize the low pH property of organic acid, and on the other hand, it can dissolve waste iron slag and waste aluminum ash by salicylic acid and citric acid. 3+ Complexation reaction increases H + The concentration further reduces the pH of the solution, which in turn promotes the dissolution of waste iron slag. The reaction principle is as follows:

[0040] 6HO-C6H4-COOH+Fe 3+ =[Fe(OC6H4COOH)6] 3- +6H +

[0041] Citric acid can be used to remove the dense oxide layer on the surface of aluminum ash, promote deep Al to participate in the reaction, and generate more active Al 3+ The reaction principle is as follows:

[0042] 3C6H8O7+2Al=Al2(C6H7O7)3+3H2↑

[0043] 6C6H8O7+2Al2O3=2Al2(C6H7O7)3+3H2O

[0044] In addition, the two organic acids salicylic acid and citric acid can be fully mixed with a water-soluble organic solvent (isopropyl alcohol solvent), and the non-polar groups in their own structures are used to form a composite system of organic acid salt-water-isopropyl alcohol, which greatly increases the collision probability of silicon with iron and aluminum salts, forming an amorphous structure of -Fe-O-Si-O-Al-, making the precursor material highly reactive.

[0045] Preferably, in step (2), the salicylic acid solution for dissolving the waste iron slag and the citric acid solution for dissolving the waste aluminum ash are both set in excess.

[0046] Further preferably, in step (2), at least 3 L of salicylic acid solution is used for every 100 g of waste iron slag, and at least 2 L of citric acid solution is used for every 100 g of waste aluminum ash.

[0047] Preferably, in step (2), the scrap iron organic acid solution and the waste aluminum organic acid solution are sealed and stored after being obtained, and specifically, the container mouth can be sealed by using plastic wrap or the like; when the scrap iron organic acid solution and the waste aluminum organic acid solution are used, the seal is opened, and after mixing, the seal is sealed again, and magnetic stirring is used to stir and mix at a speed of 800 to 1000 rpm for 30 minutes, so that the solution is fully mixed until it turns deep red; and an iron-aluminum mixed solution is obtained.

[0048] Preferably, in step (3), the water-soluble organic solvent includes alcohol organic solvents, ketone organic solvents, ether organic solvents and acid organic solvents; alcohol organic solvents include alcohol, ethanol, n-propanol, isopropanol, ethylene glycol, propylene glycol, glycerol; ketone organic solvents include acetone; ether organic solvents include tetrahydrofuran and dimethyl ether; acid organic solvents include acetic acid, etc.

[0049] Preferably, in the Al-Fe-Si mixed system of step (4), the Al-Si-Fe mixed system Si:Al=1.2 to 2.0 (molar ratio).

[0050] More preferably, in the Al-Fe-Si mixed system of step (4), Si:Fe>4.37 (molar ratio).

[0051] Preferably, in step (4), after the iron-aluminum mixed solution and the ethyl silicate solution are mixed, the container mouth is sealed again, and magnetic stirring is used to stir and mix them at 800-1000 rpm. The solution cannot be stratified. After mixing evenly, an Al-Fe-Si mixed system is obtained.

[0052] Preferably, in step (5), the water bath heating temperature is 60° C. to 70° C., and the water bath reaction time is 8 to 10 hours.

[0053] Further preferably, in step (5), the water bath heating temperature is 65° C. to 68° C. to avoid the isopropyl alcohol from being separated from the reaction system due to excessively high temperature, thereby reducing the dispersion degree of tetraethyl silicate and causing failure in the preparation of the gel material.

[0054] Preferably, in step (5), the gel system is dried by placing it in an oven at 80° C. to 100° C. to a constant weight.

[0055] Preferably, during the water bath reaction and drying, the container opening can be sealed with tin foil, and then several small holes can be made in the foil to serve as air holes. The purpose is to reduce the effect of oxygen in the air on the valence state of the ions in the solution. It is foreseeable that a vacuum environment or an inert gas environment can also achieve similar effects.

[0056] Preferably, in step (5), the muffle furnace calcination temperature should be set to 550°C to 650°C, and the temperature should be increased from room temperature at a rate of 2-8°C / min. On the one hand, the reaction activity of the precursor is improved by calcination, and on the other hand, the temperature is too high to cause the -Fe-O-Si-O- to break and cause the structure to collapse, making it impossible to form a dense network structure and reducing the alkali excitation effect.

[0057] Preferably, in step (5), the gel system is calcined in an air environment in a muffle furnace.

[0058] The present invention uses scrap iron powder and scrap aluminum ash as the main components. After activation with organic acid, they react with silicon monomers produced by hydrolysis of tetraethyl silicate to form an amorphous structure of -Fe-O-Si-O-Al-. Calcination removes excess water and other impurities in the product, promoting the formation of more pores in the gel. Further activation, such as through ball milling, enhances the reactivity of the amorphous structure. The iron-based polymer precursor obtained after calcination and ball milling is mixed with an alkaline activator. The alkaline activator's recombinant polycondensation function further polymerizes the monomers, dimers, and polymers in the precursor to form [Na,K]·[-Fe-O] x ·[-Si-O-(Al-O) (1-x) ]·[-Si-O] y It has a multi-layered mesh structure. It has excellent mechanical properties and high-temperature resistance, and compared with traditional Portland cement, its carbon emissions are reduced by about 80%. It can be widely used in various scenarios in the construction industry and is a building material with great potential in the future under the background of the dual carbon strategy.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] (1) The present invention uses two organic acids, salicylic acid and citric acid, to prepare the iron-based polymer. Both organic acids are natural materials, widely present in nature, and are relatively inexpensive to obtain. Moreover, their reactions with metals and their oxides are relatively environmentally friendly. Compared with some traditional metal ligands or catalytic materials, they have lower environmental risks and more sustainable properties.

[0061] (2) The raw materials used in the present invention are scrap iron and aluminum ash, both of which are solid wastes. Currently, there is no other more effective way to utilize such metal industrial waste except for regenerating it. The present invention reuses scrap iron and aluminum. The iron-based geopolymer material prepared by a special process can be widely used in multiple scenes and fields such as construction, municipal administration, and fire protection. It has the excellent characteristics of low carbon and environmental protection, greatly broadens the disposal channels of scrap iron and aluminum ash, and also helps the low-carbon transformation of building materials in the construction industry, and has broad application prospects.

[0062] (3) Compared with traditional geopolymer gel preparation methods, common iron mineral oxides such as hematite and magnetite can exist stably under alkaline conditions. In other words, it is difficult to bind iron atoms to the long chains of silica-alumina and become part of the structure by adding alkaline activators. Therefore, it is impossible to use traditional methods to prepare iron-based geopolymer gel materials with alkaline activators. The present invention can promote the incorporation of active iron into the structure of the geopolymer gel through acidic activation, rather than allowing the iron-containing mineral phase to serve only as filler aggregate to support the overall structure.

[0063] (4) Geopolymer gels prepared from other solid waste materials have large fluctuations in mechanical properties of the gelling materials due to the uncertainty of the components and structure of the solid waste materials themselves, which easily causes alkali cracking on the surface of the material. The iron-based polymer gel prepared by the present invention can adjust the ratio of iron and aluminum elements in the mixed solution to maintain a relative stability by monitoring the concentration of iron ions and aluminum ions during the preparation process, thereby ensuring that the components and structure of the iron-based polymer precursor material will not fluctuate significantly, and effectively ensuring the various properties of the iron-based polymer gel after alkali excitation. At the same time, after adding the alkali exciter, the small molecules on the surface of the iron-based polymer gel will gradually polymerize to form a dense surface structure, preventing the internal unreacted alkali metal from diffusing from the inside to the outside, solving the pain point of the geopolymer gelling material causing a significant decrease in strength performance due to alkali cracking. In addition, under the same water-cement ratio, as the amount of Fe gradually increases, the initial fluidity of the iron-based polymer gel will also increase, which means that compared with ordinary geopolymer gels, under the same water-cement ratio, the iron-based polymer gel has better construction operability.

[0064] (5) The geopolymer cementitious material prepared by the present invention can effectively solidify some toxic and harmful heavy metal ions, such as Cr, Cd, Zn, Pb, etc., mixed in scrap steel and scrap aluminum ash during industrial production, and can prevent the construction materials prepared from solid waste materials from harming the surrounding environment and people's health due to the dissolution of polluting heavy metal ions.

[0065] (6) The iron-based polymer gelling material precursor prepared by the present invention does not contain calcium ions, and the alkaline activator used does not use a calcium-containing solution. It belongs to a calcium-free alkaline activation system and is a true geopolymer gel.

[0066] (7) The present invention utilizes high-strength iron-based polymer cementitious materials to construct a waterproof base layer and uses it as the main material to configure permeable concrete with open-graded aggregates, so that the permeable concrete has both high-strength bearing capacity and high permeability. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 It is a flow chart of the permeable sidewalk construction method in an embodiment of the present invention.

[0068] Figure 2This is a flow chart of a method for preparing an iron-based polymer gel based on waste iron and aluminum slag provided in an embodiment of the present invention.

[0069] Figure 3 This is the X-ray diffraction pattern of the geopolymer gelling material before and after the alkali excitation reaction in Example 1 of the present invention.

[0070] Figure 4 It is the compressive strength of the iron-based polymer gel test block of scrap iron and aluminum slag prepared in Examples 1 to 6 of the present invention.

[0071] Figure 5 It is a structural diagram of a permeable sidewalk in an embodiment of the present invention.

[0072] 100-waterproof base layer, 200-permeable layer, 300-permeable surface layer, 400-open-graded raw stone aggregate. DETAILED DESCRIPTION

[0073] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of the present invention. Any equivalent conversion or substitution made by those skilled in the art based on the following embodiments is within the scope of protection of the present invention.

[0074] Example 1

[0075] like Figure 2 As shown, this embodiment provides a method for preparing an iron-based polymer precursor powder, which is specifically as follows:

[0076] (1) Take 60 parts of scrap aluminum ash and 20 parts of scrap iron and steel, crush them, and ball-mill them to 200 mesh to obtain scrap aluminum ash powder and scrap iron powder.

[0077] (2) The obtained waste aluminum ash powder and waste iron powder are added to excess citric acid solution and salicylic acid solution respectively, stirred and soaked to obtain waste aluminum citric acid solution and waste iron salicylic acid solution. The waste aluminum citric acid solution and waste iron salicylic acid solution are mixed in a beaker and a magnetic rotor for stirring is added. After the beaker mouth is sealed with plastic wrap, stirring is carried out at 800 rpm for 30 minutes until the solid matter is completely dissolved to obtain a deep red mixed solution.

[0078] (3) Ethyl silicate was weighed and dissolved in an equal amount of isopropanol with Si / Al=1.5. The mixture was stirred at 900 rpm for 30 min, sealed, and fully dissolved until the solution was uniformly mixed to obtain an ethyl silicate solution.

[0079] (4) After mixing the deep red mixed solution in step (1) and the ethyl silicate solution obtained in step (2), the mixture was stirred and sealed at 900 rpm using magnetic stirring (after mixing, the beaker mouth was sealed again with plastic wrap) until the solution did not stratify. After mixing evenly, an Al-Fe-Si mixed system was obtained.

[0080] (5) Replace the plastic wrap on the mouth of the beaker containing the Al-Fe-Si mixture with tin foil, and make several small holes in the tin foil, or use similar means to seal it. Heat the beaker containing the Al-Fe-Si mixture in a water bath at 68°C for 10 h to perform a gel reaction and obtain a gel system. Then, place the beaker containing the gel system in an oven at 80°C, seal it, and dry it to constant weight.

[0081] (6) The dried gel system was transferred into a crucible, calcined in a muffle furnace at 600 °C, and ball milled for 30 min to obtain a highly active iron-based polymer precursor powder.

[0082] (7) Add a mixed solution of sodium silicate and sodium hydroxide with a modulus of 1.79 to the iron-based polymer precursor powder obtained in step (6), adjust the water-to-binder ratio to 0.5, and stir and mix thoroughly to obtain a viscous iron-based polymer gel slurry.

[0083] (8) Pour the iron-based polymer gel slurry into a mold, seal it, and maintain it. After demolding, the iron-based polymer gel material is obtained.

[0084] (9) The sealed film was cured for 7 days, and the unconfined compressive strength of the iron-based polymer gel specimen was measured on the seventh day.

[0085] Example 2

[0086] The steps of this embodiment are the same as those of embodiment 1, except that the amount of scrap iron powder in step (1) is 10 parts.

[0087] Example 3

[0088] The steps of this embodiment are the same as those of embodiment 1, except that the amount of scrap iron powder in step (1) is 15 parts.

[0089] Example 4

[0090] The steps of this embodiment are the same as those of embodiment 1, except that the amount of scrap iron powder in step (1) is 25 parts.

[0091] Example 5

[0092] The steps of this embodiment are the same as those of embodiment 1, except that the amount of scrap iron powder in step (1) is 30 parts.

[0093] Example 6

[0094] The steps of this embodiment are the same as those of embodiment 1, except that the amount of scrap iron powder in step (1) is 35 parts.

[0095] The XRD mineral phase analysis of the gelled material obtained in Example 1 was performed before and after alkali excitation. The results are as follows: Figure 3 .Depend on Figure 3 It can be seen that before the addition of the alkaline activator, the iron-based polymer gel precursor based on scrap steel and aluminum ash already has a relatively well-defined amorphous gel phase, with a peak range of 20° to 45° and a main peak at approximately 28°. After the addition of alkaline activator, the peak range does not change significantly, but the main peak shifts to around 35°, indicating that the addition of the alkaline activator has reorganized the gel phase structure of the precursor, forming an amorphous structure of -Fe-O-Si-O-Al-, which is the main source of the material's dense structure and excellent performance.

[0096] The unconfined compressive strength of Examples 1 to 6 was measured. Figure 4 .Depend on Figure 4 It can be seen that when the addition amount of scrap iron powder is between 10 and 30 parts, the unconfined compressive strength of the test block can basically be stabilized at above 65 MPa. It can be seen that the iron-based polymer cementitious material based on scrap steel and scrap aluminum ash has higher mechanical properties.

[0097] Example 7

[0098] like Figure 1 and Figure 5 As shown, this embodiment provides a permeable sidewalk construction method:

[0099] S1. Prepare the alkaline activator for standby use;

[0100] S2. The iron-based polymer precursor powder obtained in step (6) of Example 1 was mixed with 8 parts of an alkali activator (a mixed solution of sodium silicate and sodium hydroxide with a modulus of 1.79), the water-to-binder ratio was adjusted to 0.5, and the mixture was stirred thoroughly to obtain a viscous iron-based polymer gel slurry;

[0101] S3. Compact the road soil base, support the formwork, and then pour the iron-based polymer slurry into the base to form a waterproof base 100. The thickness of the waterproof base 100 is 5 cm.

[0102] S4, 15-25 mm open-graded raw stone aggregate and iron-based polymer gel are thoroughly mixed and stirred to obtain a mixed slurry, and the mixed slurry is poured into the waterproof base in the mold supported in step S3 and leveled to obtain a permeable layer 200 (i.e., an iron-based polymer aquifer). The thickness of the permeable layer 200 is 21 cm;

[0103] S5. After coating and curing for 24 hours, the mold is removed and the coating and curing are continued for 3 to 15 days (in this example, drying for 7 days) to obtain an iron-based polymer gel permeable layer.

[0104] S6. Carry out the construction of the sidewalk accessories, lay the upper layer of permeable bricks to form a permeable surface layer 300, install the curb standing stones, and complete the construction of the permeable sidewalk. The layered structure of the sidewalk is as follows: Figure 5 shown.

[0105] Example 8

[0106] The iron-based polymer gel slurry obtained in Example 1 was mixed with 10mm-15mm raw stone aggregate in a mass ratio of 3:7. After thorough mixing, the mixture was poured into a 10cm×10cm×10cm mold. After coating, the mold was removed after curing at room temperature for 7 days to produce an iron-based polymer permeable material specimen. The specimen was placed in a large measuring cup filled with 6L of water. The volume indicated by the water level in the measuring cup after the specimen was placed was recorded. The porosity of the specimen was calculated using the water displacement method. The compressive strength of the iron-based polymer permeable material specimen was also measured after 7 days.

[0107] Example 9

[0108] The steps of this embodiment are the same as those of embodiment 8, except that the aggregate particle size is adjusted to 15mm-20mm.

[0109] Example 10

[0110] The steps of this embodiment are the same as those of embodiment 8, except that the aggregate particle size is adjusted to 20 mm-25 mm.

[0111] Example 11

[0112] The steps of this embodiment are the same as those of embodiment 8, except that the aggregate particle size is adjusted to 25mm-30mm.

[0113] The porosity and unconfined compressive strength of the iron-based polymer permeable material test blocks of Examples 8 to 11 were measured, and the results are shown in Table 1.

[0114] Table 1 Comparison of porosity and unconfined compressive strength of iron-based polymer permeable material test blocks with different graded aggregates

[0115] Aggregate size Compressive strength / MPa Porosity 10mm-15mm 11.2 27％ 15mm-20mm 10.9 36％ 20mm-25mm 9.4 39％ 25mm-30mm 6.2 43％

[0116] Table 1 shows that when using aggregates with a particle size of 10mm-30mm, the porosity is ≥27%, which is higher than the 15%-25% porosity of permeable concrete. The internal pores of the test blocks are interconnected and large in diameter, which helps prevent rain from carrying sand and gravel, leading to clogging of the voids and reducing their effectiveness. Relatively speaking, when the aggregate particle size is between 15mm and 25mm, the test blocks achieve both a larger porosity and higher compressive strength. The compressive strength of the test blocks exceeds 9.0MPa, meeting the maximum standard of 7.0MPa for road base strength in the "JTG / T F20-2015" standard. Therefore, this aggregate particle size is the most suitable for practical applications.

[0117] The above demonstrates that iron-based polymer cementitious materials derived from scrap steel and aluminum ash possess excellent mechanical properties and high-temperature resistance. This not only increases the disposal options for these scrap steel and aluminum ash, but also allows for the preparation of building materials through alkali-activated gelation, achieving energy conservation and emission reduction. Furthermore, by adjusting the formulation ratio, this material can be applied in various scenarios, expanding its functionality and possessing promising application prospects.

[0118] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A construction method for a permeable sidewalk based on an iron-based polymer cementitious material, characterized in that: Including steps: S1. Prepare the alkaline activator for standby use; S2. Mixing the iron-based polymer precursor powder and the alkaline activator, and stirring thoroughly to obtain a viscous iron-based polymer gel slurry; S3. Compact the road soil base, support the formwork, and then pour the iron-based polymer slurry into the base to form a waterproof base; S4, the 10-25mm open-graded aggregate and the iron-based polymer gel slurry are thoroughly mixed and stirred to obtain a mixed slurry, and the mixed slurry is poured into the waterproof base in the mold supported in step S3 and leveled to obtain a permeable layer; S5. After film coating and curing, the mold and film are removed to obtain the cured iron-based polymer gel water-permeable layer; S6. Lay the upper layer of permeable bricks and curb stones to complete the permeable sidewalk construction; The preparation method of the iron-based polymer precursor powder is as follows: (1) Crushing and grinding scrap iron and aluminum ash to obtain scrap iron powder and scrap aluminum ash powder; (2) using organic acid to dissolve waste iron powder and waste aluminum ash powder separately, and then mixing them to obtain an iron-aluminum mixed solution; (3) dissolving ethyl silicate in a water-soluble organic solvent to obtain an ethyl silicate solution; (4) mixing the iron-aluminum mixed solution obtained in step (2) and the ethyl silicate solution obtained in step (3) and stirring them uniformly to obtain an Al-Fe-Si mixed system; (5) heating the Al-Fe-Si mixed system in a water bath to perform a gel reaction to obtain a gel system, and drying the gel system to a constant weight; (6) The dried gel system is calcined in a muffle furnace and then ball-milled into powder to obtain a highly active iron-based polymer precursor powder.

2. The construction method according to claim 1, characterized in that: In step S1, the alkaline activator is one or more of alkali metal hydroxides, alkali metal carbonates, and alkali metal silicates.

3. The construction method according to claim 1, wherein: In step S2, iron-based polymer precursor powder and alkaline activator are mixed at a water-to-binder ratio of 0.5 to 0.

6.

4. The construction method according to claim 1, characterized in that: In step S3, the thickness of the waterproof base layer is 3-6 cm, and a slope of 1% to 2% is set in the longitudinal direction.

5. The construction method according to claim 1, characterized in that: In step S4, the mixing ratio of the open-graded aggregate and the iron-based polymer gel slurry is 5-9:3, and the thickness of the permeable layer is not less than 20 cm.

6. The construction method according to claim 1, characterized in that: The mass proportions of the waste aluminum ash, waste steel, ethyl silicate and alkali activator are 40-60 parts, 10-30 parts, 60-90 parts and 8-10 parts respectively.

7. The construction method according to claim 1, characterized in that: In step (2), the organic acid for dissolving the waste iron powder includes salicylic acid and benzoic acid, and the organic acid for dissolving the waste aluminum ash powder includes citric acid and benzoic acid.

8. The construction method according to claim 1, characterized in that: The water bath heating temperature in step (5) is 60°C to 70°C.

9. The construction method according to claim 1, characterized in that: In the Al-Fe-Si mixed system, Si:Fe>4.37.

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