Dry-mixed paving water-permeable mortar

Abstract

The invention provides dry-mixed paving permeable mortar which is prepared from the following components in parts by weight: 180 to 250 parts of Portland cement, 670 to 800 parts of modified machine-made sand, 20 to 80 parts of a composite degradable material, 0.2 to 0.6 part of a thickening agent, 0.6 to 1.0 part of a water reducing agent and 0.4 to 0.8 part of a retarder, the modified machine-made sand is sodium silicate modified graded sand compounded with hydrogen peroxide; the composite degradable material comprises modified polylactic resin particles, activated rice hull ash and starch glue. The mortar matrix is modified through mutual cooperation of the modified machine-made sand and the composite degradable material, and the problem of poor water permeability caused by blockage of internal pores in the long-term use process of traditional water-permeable mortar is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, in particular to a dry-mixed paving permeable mortar. Background Art

[0002] With the rapid advancement of urbanization, urban water resources and environmental protection face severe challenges. Sponge cities, as an innovative planning concept, offer a new approach to addressing these challenges. Permeable roads are a key component, delivering multiple benefits by promoting rainwater infiltration, reducing flood risks, and improving the ecological environment. The "permeable brick + permeable mortar + permeable concrete" structure effectively purifies, absorbs, and stores initial rainwater on roads.

[0003] However, existing permeable mortars generally have a long-term problem: pore clogging. During use, impurities such as soil flow into the mortar with rainwater, gradually filling the pores, causing its permeability coefficient to decrease, and even eventually losing its permeability. For example, the patent with application number 202110916473.6 proposes a method for preparing high elastic modulus permeable mortar using urban construction waste. The method involves the use of modified aggregates (compounded with polyvinyl alcohol solution, silica sol, and glutaraldehyde solution to form a hydrogel, then subjected to freeze-thaw treatment, and finally soaked in acrylamide glue, and then mixed with cement, water and polycarboxylate water reducer. Although the resulting mortar has good water permeability, its aggregate modification process is complicated, which is not conducive to wide application, and it also does not solve the problem of pore clogging during long-term use. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: in view of the shortcomings of the existing technology, a dry-mixed paving permeable mortar is provided, which modifies the mortar matrix by the coordinated use of modified machine-made sand and composite degradable materials, effectively solving the problem of poor permeability caused by internal pore blockage in traditional permeable mortar during long-term use.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A dry-mixed permeable mortar comprises the following components in parts by weight:

[0007] 180-250 parts of Portland cement, 670-800 parts of modified machine-made sand, 20-80 parts of composite degradable materials, 0.2-0.6 parts of thickener, 0.6-1.0 parts of water reducer, and 0.4-0.8 parts of retarder;

[0008] The modified machine-made sand is graded sand modified by sodium silicate compounded with hydrogen peroxide; the composite degradable material comprises modified polylactic acid resin particles, activated rice husk ash and starch glue.

[0009] Preferably, the silicate cement is ordinary silicate cement with a P·O 42.5, the thickener is hydroxypropyl methylcellulose, the water reducer is a polycarboxylate water reducer, and the retarder is tartaric acid.

[0010] Preferably, the method for preparing the modified machine-made sand comprises the following steps:

[0011] Mix 4-8 mesh machine-made sand, 8-16 mesh machine-made sand, and 16-30 mesh machine-made sand to obtain graded sand;

[0012] The graded sand was added into a sodium silicate solution of composite hydrogen peroxide for soaking treatment, and then the graded sand was taken out and dried at 60°C for 2h to obtain modified machine-made sand.

[0013] Preferably, the mass ratio of 4-8 mesh machine-made sand, 8-16 mesh machine-made sand, and 16-30 mesh machine-made sand is 1: (0.9-1.1): (0.05-0.2).

[0014] Preferably, the concentration of the sodium silicate solution is 5-10 wt %, the concentration of the hydrogen peroxide is 0.1-0.3 wt %, and the mass ratio of hydrogen peroxide to the sodium silicate solution is 1:(5-10).

[0015] Preferably, the soaking temperature is room temperature, and the soaking time is 10-30 minutes.

[0016] Preferably, the method for preparing the composite degradable material comprises the following steps:

[0017] The modified polylactic acid resin particles and activated rice husk ash were mixed at a low speed, and then starch glue was added in the form of a spray, and the mixture was continued to be mixed, and finally hot air dried at 40° C. for 2 hours to obtain a composite degradable material.

[0018] Preferably, the mass ratio of the modified polylactic acid resin particles to the activated rice husk ash is 1:(1-2); the solid content of the starch glue is 20wt%, and the amount of starch glue added is 5-10wt% of the total mass of the polylactic acid resin particles and the rice husk ash; the low-speed mixing speed is 150rpm, and the time is 2-4min; the continued mixing speed is 300rpm, and the time is 4-7min.

[0019] Preferably, the modified polylactic acid resin particles are prepared by mixing polylactic acid resin particles and a silane coupling agent ethanol solution having a concentration of 1-2 wt% in a mass ratio of 1:(0.015-0.025), then drying at 40° C. for 2 h, and sieving to obtain the modified polylactic acid resin particles.

[0020] Preferably, the activated rice husk ash is prepared by calcining the rice husk ash at 700° C. for 1-1.5 hours, grinding the ash, and sieving the ash.

[0021] Preferably, the starch glue is prepared by mixing corn starch and water in a mass ratio of 1:(2-4), heating to 75° C. and stirring to form a transparent colloid, and then adding 0.8-1.2 wt% of borax to the transparent colloid after cooling, stirring evenly, to obtain the starch glue.

[0022] The high-performance dry-mixed paving permeable mortar prepared by the present invention is prepared by adding water to control the water-to-material ratio to 5.4wt%-6.5wt% during use, and stirring and mixing the mortar uniformly.

[0023] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0024] The present invention provides a high-performance dry-mix paving permeable mortar, which includes cement, modified machine-made sand, composite degradable materials, thickeners, water reducers and retarders; the synergistic effect of the modified machine-made sand and the composite degradable materials in the above materials enables the mortar to have excellent permeability and mechanical properties during long-term use.

[0025] The modified machine-made sand of the present invention is modified using a sodium silicate solution compounded with hydrogen peroxide. During the modification, the hydrogen peroxide exerts an oxidizing effect, effectively removing impurities from the surface of the machine-made sand and improving the wetting and contact efficiency of the sodium silicate. Sodium silicate and hydrogen peroxide work together to induce the in-situ formation of a thin layer of silicate gel (SiO2·nH2O) on the surface of the machine-made sand. The drying process dehydrates the gel, ultimately forming a porous amorphous SiO2 coating on the surface of the machine-made sand. During use, the porous coating on the surface of the modified machine-made sand rehydrates to form a silicate gel, which effectively fills the interface transition zone between the aggregate and the cement paste, reduces the formation of microcracks, and significantly enhances the mechanical properties of the mortar.

[0026] The composite degradable material of the present invention includes modified polylactic acid resin particles, activated rice husk ash and starch glue; modified polylactic acid resin particles provide a lightweight porous skeleton in the mortar, but adding them alone will weaken the strength, activated rice husk ash exerts volcanic ash activity and enhances matrix strength; starch glue promotes the uniform dispersion of activated rice husk ash in the system, reduces agglomeration, and simultaneously improves adhesion and overall degradability. After the three components are compounded, activated rice husk ash is tightly wrapped on the surface of the modified polylactic acid resin particles. The above structure not only retains pores but also enhances interfacial bonding, thereby improving mechanical properties and water permeability. And the above composite structure effectively avoids the problem of uneven stirring caused by the single addition of modified polylactic acid resin particles (easy to float) and activated rice husk ash (easy to settle), ensures that the various components of the mortar are evenly distributed, reduces the risk of stratification, realizes complementary optimization of strength and water permeability in the mortar, and simultaneously improves the utilization rate of industrial or agricultural waste, thereby reducing the production cost of the mortar.

[0027] In addition, the composite structure of the composite degradable material of the present invention has a gradient degradation characteristic. The outer layer of activated rice husk ash and starch glue degrades first, and the inner layer of modified polylactic acid resin particles degrades later. This allows the mortar to dynamically form new pore channels during long-term use, effectively offsetting the problem of water permeability attenuation caused by the continuous filling of original pores by soil and dust, thereby maintaining the mortar's long-lasting high water permeability. DETAILED DESCRIPTION

[0028] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0029] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all the embodiments.

[0030] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0031] Example 1

[0032] A method for preparing dry-mixed permeable mortar comprises the following steps:

[0033] (1) mixing 0.1 wt% hydrogen peroxide and 5 wt% sodium silicate solution (the mass ratio of hydrogen peroxide to sodium silicate solution is 1:5) to obtain a modified solution;

[0034] (2) 4-8 mesh machine-made sand, 8-16 mesh machine-made sand, and 16-30 mesh machine-made sand were mixed in a mass ratio of 1:1:0.05 to obtain graded sand; the graded sand was added to the modified solution with the liquid level 2 cm higher than the aggregate, and soaked at room temperature for 20 minutes, then taken out and allowed to stand for 10 minutes to remove excess solution, and dried at 60°C for 2 hours to obtain modified machine-made sand;

[0035] (3) A 1 wt% KH550 ethanol solution was sprayed onto polylactic acid resin particles (Zhejiang Hainuoer Biomaterial Co., Ltd., density (1.25 ± 5) g / cm 3, melting point 155 ~ 170 ℃, tensile strength not less than 45 MPa, elongation at break 2.5%), the mass ratio of polylactic acid resin particles to KH550 ethanol solution is 1:0.02, then dried at 40 ℃ for 2 hours, and finally sieved to collect 1-3 mm particles to obtain modified polylactic acid resin particles; rice husk ash is calcined at 700 ℃ for 1 hour, then ground and passed through a 45 μm sieve to obtain activated rice husk ash; corn starch and water are mixed in a mass ratio of 1:3, heated to 75 ℃ and stirred to form a transparent colloid, and after cooling, 1wt% of borax by mass of the transparent colloid is added and stirred evenly to obtain starch glue;

[0036] (4) 400 g of modified polylactic acid resin particles and 400 g of activated rice husk ash were mixed at a low speed of 150 rpm for 3 min, and then starch glue (5 wt% of the total mass of modified polylactic acid resin particles and activated rice husk ash) was added in the form of a spray, and the speed was increased to 300 rpm and the mixing was continued for 5 min. Finally, hot air drying was carried out at 40°C for 2 h to obtain a composite biodegradable material;

[0037] (5) In parts by weight, 200 parts of P·O42.5 ordinary Portland cement, 20 parts of composite degradable materials, 0.8 parts of polycarboxylic acid water reducer, 0.5 parts of tartaric acid, and 0.2 parts of hydroxypropyl methylcellulose (viscosity of 100 Pa·s) were first added to a mixer and mixed evenly, and then 780 parts of modified machine-made sand were added and stirred to mix evenly to obtain dry-mixed paving permeable mortar.

[0038] Example 2

[0039] A method for preparing dry-mixed permeable mortar comprises the following steps:

[0040] (1) mixing 0.2 wt% hydrogen peroxide solution and 10 wt% sodium silicate solution (the mass ratio of hydrogen peroxide to sodium silicate solution is 1:5) to obtain a modified solution;

[0041] (2) 4-8 mesh machine-made sand, 8-16 mesh machine-made sand, and 16-30 mesh machine-made sand were mixed in a mass ratio of 1:1:0.1 to obtain graded sand; the graded sand was added to the modified solution with the liquid level 2 cm higher than the aggregate, and soaked at room temperature for 10 minutes, then taken out and allowed to stand for 10 minutes to remove excess solution, and dried at 60°C for 2 hours to obtain modified machine-made sand;

[0042] (3) A 1 wt% KH550 ethanol solution was sprayed onto polylactic acid resin particles (Zhejiang Hainuoer Biomaterial Co., Ltd., density of (1.25 ± 5) g / cm3, melting point of 155-170°C, tensile strength of not less than 45 MPa, and elongation at break of 2.5%) in the form of a spray, wherein the mass ratio of polylactic acid resin particles to KH550 ethanol solution was 1:0.02, and then dried at 40°C for 2 h, and finally sieved to collect 1-3 mm particles to obtain modified polylactic acid resin particles; rice husk ash was calcined at 700°C for 1 h, and then ground and sieved through a 45 μm sieve to obtain activated rice husk ash; corn starch and water were mixed in a mass ratio of 1:3, heated to 75°C and stirred to form a transparent colloid, and after cooling, 1 wt% of the mass of the transparent colloid was added with borax, and stirred evenly to obtain starch glue;

[0043] (4) 400 g of modified polylactic acid resin particles and 600 g of activated rice husk ash were mixed at a low speed of 150 rpm for 3 min, and then starch glue (5 wt% of the total mass of modified polylactic acid resin particles and activated rice husk ash) was added in the form of a spray, and the speed was increased to 300 rpm and the mixing was continued for 5 min. Finally, hot air drying was performed at 40°C for 2 h to obtain a composite biodegradable material;

[0044] (5) In parts by weight, 250 parts of P·O42.5 ordinary Portland cement, 80 parts of composite degradable materials, 0.8 parts of polycarboxylic acid water reducer, 0.6 parts of tartaric acid, and 0.2 parts of hydroxypropyl methylcellulose (viscosity of 100 Pa·s) were first added to a mixer and mixed evenly, and then 670 parts of modified machine-made sand were added and stirred to mix evenly to obtain dry-mixed permeable mortar.

[0045] Example 3

[0046] A method for preparing dry-mixed permeable mortar comprises the following steps:

[0047] (1) mixing 0.2 wt% hydrogen peroxide and 5 wt% sodium silicate solution (the mass ratio of hydrogen peroxide to sodium silicate solution is 1:8) to obtain a modified solution;

[0048] (2) 4-8 mesh machine-made sand, 8-16 mesh machine-made sand, and 16-30 mesh machine-made sand were mixed in a mass ratio of 1:1.1:0.15 to obtain graded sand; the graded sand was added to the modified solution with the liquid level 2 cm higher than the aggregate, and soaked at room temperature for 30 minutes, then removed and allowed to stand for 10 minutes to remove excess solution, and dried at 60°C for 2 hours to obtain modified machine-made sand;

[0049] (3) A 1.5 wt% KH550 ethanol solution was sprayed onto polylactic acid resin particles (Zhejiang Hainuoer Biomaterial Co., Ltd., density (1.25 ± 5) g / cm 3, melting point 155 ~ 170 ℃, tensile strength not less than 45MPa, elongation at break 2.5%), the mass ratio of polylactic acid resin particles to KH550 ethanol solution is 1:0.015, then dried at 40 ℃ for 2h, and finally sieved to collect 1-3mm particles to obtain modified polylactic acid resin particles; rice husk ash is calcined at 700 ℃ for 1h, then ground and passed through a 45μm sieve to obtain activated rice husk ash; corn starch and water are mixed in a mass ratio of 1:3, heated to 75 ℃ and stirred to form a transparent colloid, and after cooling, 1.1wt% of borax by mass of the transparent colloid is added and stirred evenly to obtain starch glue;

[0050] (4) 400 g of modified polylactic acid resin particles and 800 g of activated rice husk ash were mixed at a low speed of 150 rpm for 3 min, and then starch glue (10 wt% of the total mass of modified polylactic acid resin particles and activated rice husk ash) was added in the form of a spray, and the speed was increased to 300 rpm and the mixing was continued for 5 min. Finally, hot air drying was performed at 40°C for 2 h to obtain a composite biodegradable material;

[0051] (5) In parts by weight, 200 parts of P·O42.5 ordinary Portland cement, 40 parts of composite degradable materials, 1.0 part of polycarboxylic acid water reducer, 0.8 parts of tartaric acid, and 0.4 parts of hydroxypropyl methylcellulose (viscosity of 100 Pa·s) were first added to a mixer and mixed evenly, and then 760 parts of modified machine-made sand were added and stirred to mix evenly to obtain dry-mixed permeable mortar.

[0052] Example 4

[0053] A method for preparing dry-mixed permeable mortar comprises the following steps:

[0054] (1) mixing 0.1 wt% hydrogen peroxide solution and 8 wt% sodium silicate solution (the mass ratio of hydrogen peroxide to sodium silicate solution is 1:10) to obtain a modified solution;

[0055] (2) 4-8 mesh machine-made sand, 8-16 mesh machine-made sand, and 16-30 mesh machine-made sand were mixed in a mass ratio of 1:1:0.15 to obtain graded sand; the graded sand was added to the modified solution with the liquid level 2 cm higher than the aggregate, and soaked at room temperature for 20 minutes, then taken out and allowed to stand for 10 minutes to remove excess solution, and dried at 60°C for 2 hours to obtain modified machine-made sand;

[0056] (3) A 2 wt% KH550 ethanol solution was sprayed onto polylactic acid resin particles (Zhejiang Hainuoer Biomaterial Co., Ltd., density (1.25 ± 5) g / cm3, melting point 155-170°C, tensile strength not less than 45 MPa, elongation at break 2.5%) in the form of a spray, the mass ratio of polylactic acid resin particles to KH550 ethanol solution being 1:0.025, followed by drying at 40°C for 2 h, and finally sieving to collect 1-3 mm particles to obtain modified polylactic acid resin particles; rice husk ash was calcined at 700°C for 1.5 h, then ground and sieved through a 45 μm sieve to obtain activated rice husk ash; corn starch and water were mixed in a mass ratio of 1:3, heated to 75°C and stirred to form a transparent colloid, and after cooling, 1.2 wt% of the mass of the transparent colloid was added with borax, stirred evenly, to obtain starch glue;

[0057] (4) 400 g of modified polylactic acid resin particles and 600 g of activated rice husk ash were mixed at a low speed of 150 rpm for 3 min, and then starch glue (10 wt% of the total mass of modified polylactic acid resin particles and activated rice husk ash) was added in the form of a spray, and the speed was increased to 300 rpm and the mixing was continued for 5 min. Finally, hot air drying was performed at 40°C for 2 h to obtain a composite biodegradable material;

[0058] (5) In parts by weight, 180 parts of P·O42.5 ordinary Portland cement, 20 parts of composite degradable materials, 0.6 parts of polycarboxylic acid water reducer, 0.5 parts of tartaric acid, and 0.4 parts of hydroxypropyl methylcellulose (viscosity of 100 Pa·s) were first added to a mixer and mixed evenly, and then 800 parts of modified machine-made sand were added and stirred to mix evenly to obtain dry-mixed permeable mortar.

[0059] Comparative Example 1

[0060] The difference between this comparative example and Example 4 is that the machine-made sand is not modified, and other operations are the same as in Example 4.

[0061] Comparative Example 2

[0062] The difference between this comparative example and Example 4 is that an equal amount of modified machine-made sand is used to replace the composite degradation material, and other operations are the same as those in Example 4.

[0063] Comparative Example 3

[0064] The difference between this comparative example and Example 4 is that hydrogen peroxide is not added in step (1), and the other operations are the same as those in Example 4.

[0065] Comparative Example 4

[0066] The difference between this comparative example and Example 4 is that the polylactic acid resin particles are not modified with KH550, and other operations are the same as those in Example 4.

[0067] Comparative Example 5

[0068] The difference between this comparative example and Example 4 is that the rice husk ash is not calcined, and the other operations are the same as those in Example 4.

[0069] Comparative Example 6

[0070] The difference between this comparative example and Example 4 is that the composite degradable material does not include modified polylactic acid resin particles, and other operations are the same as those in Example 4.

[0071] Comparative Example 7

[0072] The difference between this comparative example and Example 4 is that the composite degradable material does not include activated rice husk ash, and other operations are the same as those in Example 4.

[0073] Comparative Example 8

[0074] The difference between this comparative example and Example 4 is that the composite degradable material does not include starch glue, and other operations are the same as those in Example 4.

[0075] The dry-mixed paving permeable mortar of the above embodiment and comparative example and water were respectively mixed uniformly at a water-to-material ratio of 5.7 wt% to prepare permeable mortar, and then the permeable mortar was subjected to specimen forming, curing and performance testing with reference to the JC / T 2727-2022 "Permeable Mortar" standard. The operable time was represented by the compressive strength of the cubic specimen formed after standing for 2 hours, and the compressive strength of the prismatic specimen was tested with reference to GB / T 17671. The test results are shown in Table 1.

[0076] Table 1

[0077]

[0078]

[0079] It can be seen from the test results in Table 1 that, compared with the comparative example, the embodiment of the present invention adds an appropriate amount of composite degradable material and modified machine-made sand to the cement-based material, and the two work together to effectively improve the comprehensive performance of the mortar.

[0080] The machine-made sand in Comparative Example 1 was not modified, and in Comparative Example 3, hydrogen peroxide was not added to the machine-made sand during modification. The strength of the mortar was significantly reduced. This is because the hydrogen peroxide-sodium silicate modification formed an active coating on the surface of the aggregate, which can enhance the adhesion of the aggregate. Without modification, the interface between the aggregate and the matrix was weak and the strength decreased.

[0081] Comparative Example 2 uses modified machine-made sand instead of the composite degradable material. While the mortar's strength increases, its water permeability decreases, further decreasing with increasing mortar curing time. This is because the silica gel on the surface of the modified machine-made sand fills the mortar's pores, enhancing interfacial bonding and promoting strength. However, the absence of the composite degradable material reduces the mortar's porosity, reducing its water permeability. Furthermore, over long-term curing, the mortar's internal pores refine due to the ongoing hydration reaction, and the self-healing effect increases its density, further reducing its water permeability. The composite degradable material in Comparative Example 6 does not include polylactic acid resin particles, resulting in a denser mortar with reduced water permeability. The composite degradable material in Comparative Example 7 does not include activated rice husk ash, lacking its pozzolanic effect. The cement hydration is slow, resulting in reduced mortar strength. The composite degradable material in Comparative Example 8 lacks starch glue as a bonding agent, weakening the interface between the materials and reducing mortar strength.

[0082] In Comparative Example 4, the polylactic acid resin particles were not modified with a silane coupling agent, resulting in poor compatibility between the polylactic acid resin particles and the slurry, significantly reducing the strength of the mortar. In Comparative Example 5, the rice husk ash was not calcined, and its pozzolanic activity was weak, affecting the strength of the mortar.

[0083] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal description of the claims, or if they include equivalent structural elements that are not substantially different from the literal description of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A dry-mixed permeable mortar, characterized in that: In parts by weight, it comprises the following components: 180-250 parts of Portland cement, 670-800 parts of modified machine-made sand, 20-80 parts of composite degradable materials, 0.2-0.6 parts of thickener, 0.6-1.0 parts of water reducer, and 0.4-0.8 parts of retarder; The modified machine-made sand is graded sand modified by sodium silicate compounded with hydrogen peroxide; the composite degradable material comprises modified polylactic acid resin particles, activated rice husk ash and starch glue.

2. The dry-mixed permeable mortar according to claim 1, characterized in that: The silicate cement is P·O42.5 ordinary silicate cement, the thickener is hydroxypropyl methylcellulose, the water reducer is polycarboxylate water reducer, and the retarder is tartaric acid.

3. The dry-mixed permeable mortar according to claim 1, characterized in that: The method for preparing the modified machine-made sand comprises the following steps: Mix 4-8 mesh machine-made sand, 8-16 mesh machine-made sand, and 16-30 mesh machine-made sand to obtain graded sand; The graded sand was added into a sodium silicate solution of composite hydrogen peroxide for soaking treatment, and then the graded sand was taken out and dried at 60°C for 2h to obtain modified machine-made sand.

4. The dry-mixed permeable mortar according to claim 3, characterized in that: The mass ratio of 4-8 mesh machine-made sand, 8-16 mesh machine-made sand, and 16-30 mesh machine-made sand is 1:(0.9-1.1):(0.05-0.2).

5. The dry-mixed permeable mortar according to claim 3, characterized in that: The concentration of the sodium silicate solution is 5-10 wt %, the concentration of the hydrogen peroxide is 0.1-0.3 wt %, and the mass ratio of the hydrogen peroxide to the sodium silicate solution is 1:(5-10).

6. The dry-mixed permeable mortar according to claim 3, characterized in that: The soaking temperature is room temperature, and the soaking time is 10-30 minutes.

7. The dry-mixed paving permeable mortar according to claim 1, characterized in that: The preparation method of the composite degradable material comprises the following steps: The modified polylactic acid resin particles and activated rice husk ash were mixed at a low speed, and then starch glue was added in the form of a spray, and the mixture was continued, and finally hot air dried at 40° C. for 2 hours to obtain a composite biodegradable material.

8. The dry-mixed permeable mortar according to claim 7, characterized in that: The mass ratio of the modified polylactic acid resin particles to the activated rice husk ash is 1:(1-2); the solid content of the starch glue is 20wt%, and the amount of starch glue added is 5-10wt% of the total mass of the polylactic acid resin particles and the rice husk ash; the low-speed mixing speed is 150rpm, and the time is 2-4min; the continued mixing speed is 300rpm, and the time is 4-7min.

9. The dry-mixed paving permeable mortar according to claim 7, characterized in that: The preparation method of the modified polylactic acid resin particles is as follows: polylactic acid resin particles and a silane coupling agent ethanol solution with a concentration of 1-2 wt% are mixed in a mass ratio of 1:(0.015-0.025), then dried at 40° C. for 2 hours, and sieved to obtain the modified polylactic acid resin particles.

10. The dry-mixed paving permeable mortar according to claim 7, characterized in that: The preparation method of the activated rice husk ash is as follows: calcining the rice husk ash at 700°C for 1-1.5 hours, grinding the rice husk ash, and sieving the activated rice husk ash; the preparation method of the starch glue is as follows: mixing corn starch and water in a mass ratio of 1:(2-4), heating to 75°C and stirring to form a transparent colloid, and after cooling, adding 0.8-1.2wt% of borax by mass of the transparent colloid and stirring evenly to obtain the activated rice husk ash.

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