A full-solid-waste geopolymer stable desert sand pavement base material and a preparation method thereof

Abstract

This invention relates to the field of road engineering technology, and proposes a solid waste geopolymer-stabilized desert sand pavement base material and its preparation method. The pavement base material comprises desert sand, fly ash, slag, and an alkali activator, wherein the alkali activator comprises water glass, sodium hydroxide, water, and a sodium acrylate-acrylamide polymer. This invention introduces a sodium acrylate-acrylamide polymer into existing alkali activators (water glass, NaOH), effectively improving the dispersion stability of the activator in the system, while also enhancing the wettability and contact uniformity between the activator and the base material particles, promoting a more complete geopolymer reaction. Furthermore, it helps improve the film-forming ability of the geopolymer gel phase and the integrity of the three-dimensional network structure, thereby enhancing the compressive strength and splitting strength of the pavement material.

Description

Technical Field

[0001] This invention relates to the field of road engineering technology, and in particular to a solid waste geopolymer stabilized desert sand pavement base material and its preparation method. Background Technology

[0002] In recent years, my country's highway construction has developed rapidly, with its total expressway mileage ranking first in the world. Fly ash and slag contain a large amount of amorphous silica-alumina structures, which can be used to prepare geopolymer inorganic cementitious materials to replace traditional silicate cement materials, thereby reducing carbon emissions. In addition, my country has vast desert areas with abundant desert sand reserves. If desert sand can be used as fine aggregate to replace river sand in road base courses, it can not only solve the material shortage problem, but also provide a new solution for the design of road base courses in arid desert areas.

[0003] In practical applications, the alkali activator used in geopolymer systems has excessively high viscosity, failing to disperse sufficiently, which in turn leads to low compressive strength and splitting tensile strength of geopolymer-stabilized desert sand pavement base materials. Therefore, there is a need for a solid waste geopolymer-stabilized desert sand pavement base material and its preparation method that can improve both compressive strength and splitting tensile strength. Summary of the Invention

[0004] In view of this, the present invention proposes a solid waste geopolymer stabilized desert sand pavement base material and its preparation method that can improve compressive strength and splitting tensile strength.

[0005] The technical solution of the present invention is implemented as follows: On the one hand, the present invention provides a solid waste geopolymer stabilized desert sand pavement base material, the pavement base material comprising desert sand, fly ash, slag and alkali activator, the alkali activator comprising water glass, sodium hydroxide, water and sodium acrylate-acrylamide polymer.

[0006] This invention introduces a sodium acrylate-acrylamide polymer into existing alkali activators (water glass, NaOH), which effectively improves the dispersion stability of the activator in the system, preventing excessively high local concentrations or precipitation. Simultaneously, it enhances the wettability and contact uniformity between the activator and precursor particles such as fly ash and slag, promoting a more complete geopolymer reaction. Furthermore, this polymer helps improve the film-forming ability of the geopolymer gel phase and the integrity of its three-dimensional network structure, thereby significantly improving the early strength development and later mechanical properties of the material, ultimately resulting in a significant increase in compressive strength and splitting strength.

[0007] Based on the above technical solutions, preferably, the road base material, by weight, includes 1700 parts desert sand, 140-160 parts fly ash, 140-160 parts slag, 27-30 parts water glass, 6-7 parts sodium hydroxide, 165-180 parts water, and 0.20-0.25 parts sodium acrylate-acrylamide polymer.

[0008] Based on the above technical solutions, preferably, the road base material also includes active silica and nano titanium dioxide.

[0009] Specifically, activated silica (white carbon black) can rapidly participate in the alkali-activated reaction of geopolymers, providing an additional silicon source and promoting the formation of NASH gel, thereby increasing the degree of reaction and early strength development. Simultaneously, as a micro / nano-scale filler, activated silica can effectively fill the pores between powder particles, optimize particle size distribution, and improve the density of the matrix. Nano-titanium dioxide can further fill micropores and interface defects, enhancing the system's compactness. It can also promote the nucleation and growth of the gel phase through surface effects, improving the uniformity of the microstructure. The synergistic effect of both is significant: activated silica (white carbon black) focuses on chemical activity and micron-scale filling, while nano-titanium dioxide strengthens nanoscale physical filling and structural densification. The two complement each other at different scales, jointly promoting the full development and structural densification of the geopolymer gel network, thereby significantly improving the material's compressive strength and splitting resistance.

[0010] Based on the above technical solutions, preferably, the mass ratio of desert sand, active silica and nano titanium dioxide is 1700:15-25:18-22.

[0011] Based on the above technical solutions, preferably, the road base material also includes hollow glass microspheres and polypropylene fibers.

[0012] Specifically, hollow glass microspheres significantly improve the workability and flowability of mixtures, promote uniform dispersion of components, reduce internal porosity, and their fine particles fill voids in the matrix, optimizing particle packing structure and improving material density and overall uniformity. Meanwhile, polypropylene fibers, through their three-dimensional random distribution within the matrix, act as crack bridges, effectively inhibiting the generation and propagation of microcracks, improving tensile strength and toughness, and significantly enhancing crack resistance and splitting strength. The synergistic effect of both is evident: hollow glass microspheres improve the rheological properties of the system, facilitating the uniform dispersion of polypropylene fibers in the matrix and preventing agglomeration, thus fully leveraging their reinforcing effect; simultaneously, the presence of fibers also constrains potential stress concentration around the glass microspheres, preventing microcracks from propagating from the microsphere interface. The two complement each other in improving density and crack resistance, achieving an organic combination of "micro-filling reinforcement" and "fiber crack prevention," jointly enhancing the comprehensive mechanical properties and durability of road base materials.

[0013] Based on the above technical solutions, preferably, the hollow glass microspheres have a particle size of 25-35μm and the polypropylene fibers have a length of 5-8mm.

[0014] Based on the above technical solutions, preferably, the mass ratio of the desert sand, hollow glass microspheres and polypropylene fibers is 1700:8-12:3-5.

[0015] Based on the above technical solutions, preferably, the desert sand has a SiO2 content ≥76wt%, an Al2O3 content ≥9.6wt%, and a particle size of 0.075~0.4mm; the slag powder has a SiO2 content ≥34wt% and a CaO content ≥35wt%; and the fly ash has a SiO2 content ≥43wt% and an Al2O3 content ≥23wt%.

[0016] Based on the above technical solutions, preferably, the active silica is fumed silica.

[0017] On the other hand, the present invention also provides a method for preparing a solid waste geopolymer-stabilized desert sand pavement base material, comprising the following steps:

[0018] S1, Preparation of alkali activator: Add water glass to water and stir until dissolved, add sodium hydroxide and stir until dissolved, add sodium acrylate-acrylamide polymer and stir thoroughly to obtain alkali activator;

[0019] S2, add desert sand, nano titanium dioxide, polypropylene fiber, hollow glass microspheres and the alkali activator from step S1 into a mixer and mix evenly, then place in a sealed container and let it sit for 1.5-2.5 hours.

[0020] S3. Mix fly ash, slag and active silica evenly, and then stir evenly with the material prepared in step S2 to obtain desert sand road base material.

[0021] Based on the above technical solutions, preferably, the modulus of water glass in the alkali activator is 1.0.

[0022] Based on the above technical solutions, preferably, the dry density of the road base material is 1.835-1.920 g / cm³. 3 The moisture content is 9.60%-10.28%.

[0023] The present invention provides a solid waste geopolymer-stabilized desert sand pavement base material and its preparation method, which have the following advantages over the prior art:

[0024] This invention improves the dispersibility and reaction uniformity of the activator by introducing a sodium acrylate-acrylamide polymer into the alkali activator, providing a favorable chemical environment for the full formation of the geopolymer gel. Further addition of reactive silica (white carbon black) and nano-titanium dioxide not only participates in the reaction with high activity but also achieves multi-level filling at the micro- and nano-scale, significantly improving the matrix density and structural stability. Furthermore, hollow glass microspheres and polypropylene fibers are introduced; the former improves workability and assists in filling, while the latter provides crack resistance and toughening.

[0025] The above three-layer improvement is progressive and synergistic: the polymer ensures the uniform initiation of the reaction, the active components and nanofillers construct a dense gel structure, and the microbeads and fibers further optimize the physical structure and mechanical properties on this basis, realizing a full-chain synergistic enhancement from "reaction promotion" to "structural strengthening" and then to "toughness improvement", ultimately enabling the solid waste geopolymer stabilized desert sand material to have high strength, high toughness, durability and good construction performance. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] The fly ash used in this invention has a density of 2.55 g / cm³. 3 The original moisture content was 0.6%, SiO2 content was ≥43wt%, and Al2O3 content was ≥23wt%. The density of the slag powder was 3.10 g / cm³. 3 The original moisture content was 0.6 wt%, and the SiO₂ content was 0.6 wt%. 2Content ≥34wt%, CaO content ≥35wt%.

[0028] The fly ash selected was Class F Grade I fly ash from Henan Wuhu Environmental Protection Technology Co., Ltd., and the slag powder selected was S95 slag powder from Henan Mengdian Cement Co., Ltd. The main characteristics are shown in Table 1.

[0029] Table 1 Chemical composition and physical properties of fly ash and slag

[0030]

[0031] The sodium hydroxide is commercially available in flake form, with a mass percentage of 99%.

[0032] Water glass was purchased from Henan Shibang Chemical Co., Ltd., with a density of 1.51 g / cm³. 3 The specific parameters are shown in Table 2.

[0033] Table 2 Physicochemical properties of water glass

[0034]

[0035] The desert sand was taken from the Kubuqi Desert in Inner Mongolia Autonomous Region. It has a SiO2 content of ≥76wt%, an Al2O3 content of ≥9.6wt%, a particle size distribution of 0.075~0.3mm, and an original moisture content of <1%.

[0036] The activated silica (white carbon black) was purchased from Henan Jude Chemical Co., Ltd., with a purity of 99.99% and an average particle size of 1μm.

[0037] Nano titanium dioxide was purchased from Shanghai Maclean Reagent Co., Ltd.

[0038] The hollow glass microspheres were purchased from Henan Yixiang New Materials Co., Ltd. They are hollow spherical with a particle size of 30μm.

[0039] The sodium acrylate-acrylamide polymer had a purity of 90% and was purchased from Guangdong Yuanfeng Chemical Reagent Co., Ltd.

[0040] The polypropylene fibers are flat, 6mm in length, and were purchased from Hebei Chuangsheng Building Materials & Chemical Co., Ltd.

[0041] The preparation method of the all-solid waste geopolymer stabilized desert sand pavement base course of this invention is based on the Chinese standard "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG 3441—2024), and the steps are as follows:

[0042] S1. Maximum dry density and optimum moisture content tests of geopolymers and different desert sands.

[0043] For different desert sand pavement base materials, different desert sands, fly ash, slag, active silica, nano titanium dioxide and polypropylene fibers were weighed according to the above weight proportions, mixed evenly, and heavy compaction tests were carried out according to the Chinese standard "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG 3441-2024). The optimum moisture content and maximum dry density of different desert sands under these conditions were determined.

[0044] S2. Preparation of modified alkali activator:

[0045] An alkali activator is prepared by mixing 163-175 parts water, 27-30 parts water glass, 6-7 parts sodium hydroxide, and 0.20-0.25 parts polyacrylamide-sodium acrylate copolymer at the optimal moisture content.

[0046] The preparation process involves dissolving water glass in water and stirring thoroughly to obtain a 10% concentration water glass solution. Then, sodium hydroxide solid particles are added to the 10% concentration water glass solution to adjust the modulus to 1.0. After thorough stirring to ensure complete dissolution of the sodium hydroxide, (polyacrylamide-sodium acrylate copolymer is added) and further stirring yields the (modified) alkali activator.

[0047] S3, Desert Sand with Encased Material:

[0048] Weigh out 1700 parts of desert sand, (15-25 parts of nano titanium dioxide), (3-5 parts of polypropylene fiber), and (8-12 parts of hollow glass microspheres), mix them evenly with the prepared alkali activator using a mixer (stir for 2 minutes), and place them in a black plastic bag to ferment for 2 hours.

[0049] S4. Preparation of road base course specimens:

[0050] Mix 140-160 parts of weighed fly ash, 140-160 parts of slag, and 15-25 parts of (active silica) evenly. Then, mix this mixture thoroughly with the desert sand mixture prepared in S3. According to the revised "Test Procedure for Inorganic Binder Stabilized Materials in Highway Engineering" (JTG 3441—2024), calculate the weight of each specimen based on the measured maximum dry density and optimum moisture content, and at 98% compaction. The revised standard formula is as follows:

[0051] Standard mass of a single specimen:

[0052] ;

[0053] Where: V—sample volume (cm³) 3 ), W Geo —Optimal moisture content of the mixture (%), ρ max —Maximum dry density of the mixture (g / cm³) 3), γ—compaction standard of mixture (%), m0—mass of mixture (g), ρ 激发剂 —The overall density of the activator.

[0054] The density of the alkaline activator is:

[0055] ;

[0056] In the formula: ρ 激发剂 —The overall density of the activator, V—The volume of water required under the optimal moisture content of the material during curing, C—The concentration of the activator, ρ 水 —The density of water, ρ 水玻璃 —Density of water glass, m NaOH —The mass of NaOH required at a given concentration and modulus. m bb —The quality of the polyacrylamide-sodium acrylate copolymer.

[0057] Considering the mass loss during the specimen forming process, the mass of each specimen can be increased by 0-2% in actual operation, that is:

[0058] ;

[0059] In the formula: —The final determined mass, m0—the mass of the mixture (g), δ—the redundancy (%) in calculating the mass of the mixture (value 1%).

[0060] Total mass of dry material (including dry soil and inorganic binder) for each specimen:

[0061] ;

[0062] Where: m1—mass of dry mixture (g) —The final determined mass, W Geo —Optimal moisture content of the mixture (%), ρ 激发剂 —The overall density of the activator.

[0063] Mass of inorganic binder in each specimen:

[0064] External doping method

[0065] ;

[0066] Where: m1—mass of dry mixture (g), m2—mass of inorganic binder (g), α—dosage of inorganic binder (%).

[0067] Dry soil mass in each specimen:

[0068] ;

[0069] Where: m3—mass of dry soil (g), m1—mass of dry mixture (g), m2—mass of inorganic binder (g).

[0070] Water content in each specimen:

[0071] ;

[0072] Where: m w —Water added mass (g); m2—Inorganic binder mass (g); m3—Dry soil mass (g); W Geo —Optimal moisture content of the mixture (%), ρ 激发剂 —The overall density of the activator.

[0073] Verification:

[0074] ;

[0075] In the formula: —The final determined mass, m2—mass of inorganic binder (g), m3—mass of dry soil (g), m w —Water mass added (g).

[0076] Example 1

[0077] The solid waste geopolymer stabilized desert sand pavement base material of this embodiment includes 1700g of desert sand, 150g of fly ash, 150g of slag, 29.36g of water glass, 6.63g of sodium hydroxide, 175.03g of water, and 0.2g of sodium acrylate-acrylamide polymer.

[0078] A method for preparing a solid waste geopolymer-stabilized desert sand pavement base material includes the following steps:

[0079] S1, Preparation of the alkali activator: Dissolve water glass in water and stir thoroughly to obtain a 10% water glass solution. Then add sodium hydroxide solid particles to the above 10% water glass solution to adjust the modulus to 1.0; stir thoroughly to ensure the sodium hydroxide is completely dissolved, and finally add sodium acrylate-acrylamide polymer and stir thoroughly to obtain the alkali activator.

[0080] S2, add desert sand and the alkali activator from step S1 into a mixer and mix evenly, then place in a sealed container (black plastic bag) and let it sit for 2 hours;

[0081] S3. Mix fly ash and slag evenly, and then stir them evenly with the material prepared in step S2 to obtain the desert sand road base material.

[0082] Example 2

[0083] The solid waste geopolymer stabilized desert sand pavement base material of this embodiment includes 1700g of desert sand, 150g of fly ash, 150g of slag, 20g of activated silica, 20g of nano titanium dioxide, 28.19g of water glass, 6.37g of sodium hydroxide, 168.05g of water, and 0.2g of sodium acrylate-acrylamide polymer.

[0084] A method for preparing a solid waste geopolymer-stabilized desert sand pavement base material includes the following steps:

[0085] S1, Preparation of the alkali activator: Dissolve water glass in water and stir thoroughly to obtain a 10% water glass solution. Then add sodium hydroxide solid particles to the above 10% water glass solution to adjust the modulus to 1.0; stir thoroughly to ensure the sodium hydroxide is completely dissolved, and finally add sodium acrylate-acrylamide polymer and stir thoroughly to obtain the alkali activator.

[0086] S2, add desert sand, nano titanium dioxide and the alkali activator from step S1 into a mixer and mix evenly, then place in a sealed container (black plastic bag) and let it sit for 2 hours;

[0087] S3. Mix fly ash, slag and active silica evenly, and then stir evenly with the material prepared in step S2 to obtain desert sand road base material.

[0088] Example 3

[0089] The solid waste geopolymer stabilized desert sand pavement base material of this embodiment includes 1700g desert sand, 150g fly ash, 150g slag, 10g hollow glass microspheres, 4g polypropylene fiber, 20g activated silica, 20g nano titanium dioxide, 27.80g water glass, 6.28g sodium hydroxide, 165.71g water, and 0.2g sodium acrylate-acrylamide polymer.

[0090] A method for preparing a solid waste geopolymer-stabilized desert sand pavement base material includes the following steps:

[0091] S1, Preparation of the alkali activator: Dissolve water glass in water and stir thoroughly to obtain a 10% water glass solution. Then add sodium hydroxide solid particles to the above 10% water glass solution to adjust the modulus to 1.0; stir thoroughly to ensure the sodium hydroxide is completely dissolved, and finally add sodium acrylate-acrylamide polymer and stir thoroughly to obtain the alkali activator.

[0092] S2, add desert sand, nano titanium dioxide, polypropylene fiber, hollow glass microspheres and alkali activator from step S1 into a mixer and mix evenly, then place in a sealed container (black plastic bag) and let it sit for 2 hours.

[0093] S3. Mix fly ash, slag and active silica evenly, and then stir evenly with the material prepared in step S2 to obtain desert sand road base material.

[0094] Example 4

[0095] The solid waste geopolymer stabilized desert sand pavement base material of this embodiment includes 1700g desert sand, 140g fly ash, 160g slag, 8g hollow glass microspheres, 3g polypropylene fiber, 15g activated silica, 18g nano titanium dioxide, 27.95g water glass, 6.31g sodium hydroxide, 166.61g water, and 0.25g sodium acrylate-acrylamide polymer.

[0096] A method for preparing a solid waste geopolymer-stabilized desert sand pavement base material includes the following steps:

[0097] S1, Preparation of the alkali activator: Dissolve water glass in water and stir thoroughly to obtain a 10% water glass solution. Then add sodium hydroxide solid particles to the above 10% water glass solution to adjust the modulus to 1.1; stir thoroughly to ensure the sodium hydroxide is completely dissolved, and finally add sodium acrylate-acrylamide polymer and stir thoroughly to obtain the alkali activator.

[0098] S2, add desert sand, nano titanium dioxide, polypropylene fiber, hollow glass microspheres and alkali activator from step S1 into a mixer and mix evenly, then place in a sealed container (black plastic bag) and let it sit for 2 hours.

[0099] S3. Mix fly ash, slag and active silica evenly, and then stir evenly with the material prepared in step S2 to obtain desert sand road base material.

[0100] Example 5

[0101] The solid waste geopolymer stabilized desert sand pavement base material of this embodiment includes 1700g desert sand, 160g fly ash, 140g slag, 9g hollow glass microspheres, 5g polypropylene fiber, 25g activated silica, 19g nano titanium dioxide, 24.4g water glass, 6.2g sodium hydroxide, 163.75g water, and 0.22g sodium acrylate-acrylamide polymer.

[0102] A method for preparing a solid waste geopolymer-stabilized desert sand pavement base material includes the following steps:

[0103] S1, Preparation of the alkali activator: Dissolve water glass in water and stir thoroughly to obtain a 10% water glass solution. Then add sodium hydroxide solid particles to the above 10% water glass solution to adjust the modulus to 1; stir thoroughly to ensure the sodium hydroxide is completely dissolved, and finally add sodium acrylate-acrylamide polymer and stir thoroughly to obtain the alkali activator.

[0104] S2, add desert sand, nano titanium dioxide, polypropylene fiber, hollow glass microspheres and alkali activator from step S1 into a mixer and mix evenly, then place in a sealed container (black plastic bag) and let it sit for 2 hours.

[0105] S3. Mix fly ash, slag and active silica evenly, and then stir evenly with the material prepared in step S2 to obtain desert sand road base material.

[0106] Example 6

[0107] The solid waste geopolymer stabilized desert sand pavement base material of this embodiment includes 1700g desert sand, 150g fly ash, 150g slag, 12g hollow glass microspheres, 4.5g polypropylene fiber, 22g activated silica, 22g nano titanium dioxide, 27.38g water glass, 6.18g sodium hydroxide, 163.21g water, and 0.23g sodium acrylate-acrylamide polymer.

[0108] A method for preparing a solid waste geopolymer-stabilized desert sand pavement base material includes the following steps:

[0109] S1, Preparation of the alkali activator: Dissolve water glass in water and stir thoroughly to obtain a 10% water glass solution. Then add sodium hydroxide solid particles to the above 10% water glass solution to adjust the modulus to 1.0; stir thoroughly to ensure the sodium hydroxide is completely dissolved, and finally add sodium acrylate-acrylamide polymer and stir thoroughly to obtain the alkali activator.

[0110] S2, add desert sand, nano titanium dioxide, polypropylene fiber, hollow glass microspheres and alkali activator from step S1 into a mixer and mix evenly, then place in a sealed container (black plastic bag) and let it sit for 2 hours.

[0111] S3. Mix fly ash, slag and active silica evenly, and then stir evenly with the material prepared in step S2 to obtain desert sand road base material.

[0112] Example 7

[0113] The difference between this embodiment and Embodiment 1 is that the road base material contains added active silica and nano-titanium dioxide, specifically:

[0114] The solid waste geopolymer stabilized desert sand pavement base material of this embodiment includes 1700g desert sand, 150g fly ash, 150g slag, 20g activated silica, 20g nano titanium dioxide, 30.23g water glass, 6.99g sodium hydroxide, 177.03g water, and 0.2g sodium acrylate-acrylamide polymer.

[0115] The preparation method of the all-solid waste geopolymer stabilized desert sand pavement base material is the same as in Example 2.

[0116] Example 8

[0117] The difference between this embodiment and Embodiment 7 is that hollow glass microspheres and polypropylene fibers have been added to the road base material, specifically:

[0118] The solid waste geopolymer stabilized desert sand pavement base material of this embodiment includes 1700g desert sand, 150g fly ash, 150g slag, 10g hollow glass microspheres, 4g polypropylene fiber, 20g activated silica, 20g nano titanium dioxide, 30.23g water glass, 6.99g sodium hydroxide, 177.03g water, and 0.2g sodium acrylate-acrylamide polymer.

[0119] The preparation method of the all-solid-waste geopolymer stabilized desert sand pavement base material is the same as in Example 3:

[0120] Comparative Example 1

[0121] Compared with Example 1, Comparative Example 1 lacks the sodium acrylate-acrylamide polymer, but the rest is the same as Example 1.

[0122] Comparative Example 2

[0123] Compared with Example 2, Comparative Example 2 lacks nano-titanium dioxide and sodium acrylate-acrylamide polymer. At the same time, the amounts of water glass, sodium hydroxide and water were modified to 29.97g, 6.78g and 178.66g respectively according to the optimal water content. The rest of the contents are the same as in Example 2.

[0124] Comparative Example 3

[0125] Compared with Example 2, Comparative Example 3 lacks active silica and sodium acrylate-acrylamide polymer. At the same time, the amounts of water glass, sodium hydroxide and water were modified to 28.86g, 6.52g and 171.99g respectively according to the optimal water content. The rest of the contents are the same as in Example 2.

[0126] Comparative Example 4

[0127] Compared with Example 2, Comparative Example 4 lacks the sodium acrylate-acrylamide polymer, and the amounts of water glass, sodium hydroxide, and water are modified to 28.19 g, 6.37 g, and 168.05 g respectively according to the optimal water content. The rest of the contents are the same as in Example 2.

[0128] Comparative Example 5

[0129] Compared with Example 3, Comparative Example 5 lacks nano-titanium dioxide, active silica, hollow glass microspheres, and sodium acrylate-acrylamide polymer. At the same time, the amounts of water glass, sodium hydroxide, and water were modified to 28.92g, 6.53g, and 172.35g, respectively, according to the optimal water content. The rest of the contents are the same as in Example 3.

[0130] Comparative Example 6

[0131] Compared with Example 3, Comparative Example 6 lacks nano-titanium dioxide, active silica, polypropylene fiber, and sodium acrylate-acrylamide polymer. At the same time, the amounts of water glass, sodium hydroxide, and water were modified to 28.71g, 6.48g, and 171.01g, respectively, according to the optimal water content. The rest of the contents are the same as in Example 3.

[0132] Comparative Example 7

[0133] Compared with Example 3, Comparative Example 7 lacks nano-titanium dioxide, active silica, and sodium acrylate-acrylamide polymer. At the same time, the amounts of water glass, sodium hydroxide, and water were modified to 28.56g, 6.45g, and 170.20g, respectively, according to the optimal water content. The rest of the contents are the same as in Example 3.

[0134] Comparative Example 8

[0135] Compared with Example 3, Comparative Example 8 lacked hollow glass microspheres and sodium acrylate-acrylamide polymer. At the same time, the amounts of water glass, sodium hydroxide and water were modified to 28.10g, 6.34g and 167.51g according to the optimal water content. The rest of the contents were the same as in Example 3.

[0136] Comparative Example 9

[0137] Compared with Example 3, Comparative Example 9 lacked the sodium acrylate-acrylamide polymer, and the amounts of water glass, sodium hydroxide, and water were modified to 27.80 g, 6.28 g, and 165.71 g, respectively, according to the optimal water content. The rest of the contents were the same as in Example 3.

[0138] Comparative Example 10

[0139] Compared with Example 1, Comparative Example 10 has a sodium acrylate-acrylamide polymer content that exceeds the specified range, specifically 0.4, while the rest is the same as in Example 1.

[0140] Comparative Example 11

[0141] Compared with Example 7, Comparative Example 11 lacks nano-titanium dioxide, but the rest is the same as Example 7.

[0142] Comparative Example 12

[0143] Compared with Example 8, Comparative Example 12 lacks hollow glass microspheres, but the rest is the same as Example 8.

[0144] Table 3 Raw material composition (g) of the Examples and Comparative Examples

[0145]

[0146] The road base materials prepared in the examples and comparative examples were injected into a cylindrical mold with a size of φ=50mm and prepared by static pressing to obtain cylindrical specimens with a diameter of 50mm and a height of 50mm. Two hours after preparation, the specimens were demolded on a demolding machine, wrapped in plastic bags, and placed in a standard curing room for 7 days to obtain solid waste geopolymer stabilized desert sand road base specimens.

[0147] After a 7-day curing period, the specimens were removed from the curing room and immersed in deionized water for one day. The tests were conducted using an electro-hydraulic servo universal testing machine, with a continuous uniform load applied under computer control. The loading rate was 1 mm / min as specified in the "Test Procedure for Inorganic Binder Stabilized Materials in Highway Engineering" (JTG 3441—2024). Six specimens were prepared for each group, and the results were obtained according to the requirements of the "Test Procedure for Inorganic Binder Stabilized Materials in Highway Engineering" (JTG 3441—2024).

[0148] Table 4 Compressive strength and splitting tensile strength of geopolymer-stabilized desert sand pavement base materials

[0149]

[0150] As shown in Table 4, compared with Comparative Example 1, the addition of polyacrylamide-sodium acrylate copolymer to the activator in Example 1 makes the activator better dispersed, increases the uniformity of contact between the activator and the geopolymer powder, and thus improves the compressive strength and splitting strength.

[0151] Comparative Examples 1-3 show that adding reactive silica indirectly increases the reactants, improves the reactivity of the geopolymer powder, and fills pores, thereby improving compressive strength and cratering resistance. Adding nano-titanium dioxide increases the filler content within the system, improving overall density and filling pores, thus enhancing compressive strength and cratering resistance. Adding both reactive silica and nano-titanium dioxide increases both reactants and filler content within the system, improving both the reactivity of the geopolymer powder and further filling pores.

[0152] Comparative Examples 1 and 5-7 show that adding polypropylene fibers increases the amount of fine filler in the system and blocks crack propagation paths, improving both the tensile strength of the road base material and further filling pores. Therefore, compared to Comparative Example 1, Comparative Example 5 shows a slight increase in compressive strength and a significant improvement in pothole splitting resistance. Adding hollow glass microspheres increases the amount of fine filler in the system and improves its fluidity, resulting in a more uniform particle distribution and further filling pores. Therefore, compared to Comparative Example 1, Comparative Example 6 shows an increase in compressive strength and a significant improvement in pothole splitting resistance. The addition of both polypropylene fibers and hollow glass microspheres increases the amount of fine filler in the system, improving the tensile strength of the road base material. Simultaneously, the hollow glass microspheres enhance the uniformity of the system and the uniformity of the fibers within the system, thereby improving its splitting resistance.

[0153] Comparative Example 8 added activated silica, nano-titanium dioxide, and polypropylene fibers, which increased the amount of fine filler in the system and blocked crack propagation paths, thus enhancing the system's density and further improving compressive and splitting resistance. Comparative Example 9, based on Comparative Example 8, added polypropylene fibers, increasing the overall density and enhancing tensile stress. Compared to Comparative Example 9, Example 3 added polyacrylamide-sodium acrylate copolymer to the activator, making the activator more uniform and thus improving the system's compressive and tensile strength.

[0154] As shown in Comparative Example 10, when the added polyacrylamide-sodium acrylate copolymer exceeds the specified range, it will form an overly dense polymer network in the system, which will hinder the free diffusion of alkali-activated ions, affect the full progress of the geopolymer reaction, and lead to incomplete gel phase formation. This will result in a decrease in the density and internal bonding of the material, and thus a reduction in both compressive and tensile strength.

[0155] In summary, the desert sand concrete examples 3-6 can achieve a good dual improvement in compressive strength and splitting tensile strength, exhibiting excellent comprehensive mechanical properties, and represent a feasible mix design approach suitable for high-performance low-carbon concrete materials.

[0156] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A solid waste geopolymer-stabilized desert sand pavement base material, characterized in that, The road base material includes desert sand, fly ash, slag, and an alkali activator, wherein the alkali activator includes water glass, sodium hydroxide, water, and sodium acrylate-acrylamide polymer; Based on the weight percentages, the composition is as follows: 1700 parts desert sand, 140-160 parts fly ash, 140-160 parts slag, 27-30 parts water glass, 6-7 parts sodium hydroxide, 163-175 parts water, and 0.20-0.25 parts sodium acrylate-acrylamide polymer. The road base material also includes activated silica and nano-titanium dioxide, wherein the activated silica is white carbon black with an average particle size of 1μm; The mass ratio of the desert sand, active silica, and nano titanium dioxide is 1700:15-25:18-22.

2. The all-solid waste geopolymer stabilized desert sand pavement base material as described in claim 1, characterized in that, The road base material also includes hollow glass microspheres and polypropylene fibers.

3. The all-solid waste geopolymer stabilized desert sand pavement base material as described in claim 2, characterized in that, The mass ratio of the desert sand, hollow glass microspheres, and polypropylene fibers is 1700:8-12:3-5.

4. The all-solid waste geopolymer stabilized desert sand pavement base material as described in claim 1, characterized in that, The desert sand contains ≥76wt% SiO2, ≥9.6wt% Al2O3, and has a particle size of 0.075~0.4mm; the slag contains ≥34wt% SiO2 and ≥35wt% CaO; and the fly ash contains ≥43wt% SiO2 and ≥23wt% Al2O3.

5. The preparation method of a solid waste geopolymer-stabilized desert sand pavement base material as described in claim 2, characterized in that, Includes the following steps: S1, Preparation of alkali activator: Add water glass to water and stir until dissolved, add sodium hydroxide and stir until dissolved, add sodium acrylate-acrylamide polymer and stir thoroughly to obtain alkali activator; S2, add desert sand, nano titanium dioxide, polypropylene fiber, hollow glass microspheres and the alkali activator from step S1 into a mixer and mix evenly, then place in a sealed container and let it sit for 1.5-2.5 hours. S3. Mix fly ash, slag and active silica evenly, and then stir evenly with the material prepared in step S2 to obtain desert sand road base material.

6. The preparation method of a solid waste geopolymer-stabilized desert sand pavement base material as described in claim 5, characterized in that, The modulus of the water glass in the alkaline activator is 1.

0.

7. The preparation method of a solid waste geopolymer-stabilized desert sand pavement base material as described in claim 5, characterized in that, The dry density of the road base material is 1.835-1.920 g / cm³. 3 The moisture content is 9.60%-10.28%.

Images