All-solid waste geopolymer stabilized desert sand pavement base material and preparation method thereof

Abstract

The invention relates to the technical field of road engineering, and provides an all-solid waste geopolymer stabilized desert sand pavement base material and a preparation method thereof. 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. The sodium acrylate-acrylamide polymer is introduced on the basis of the existing alkali activator (water glass and NaOH), so that the dispersion stability of the activator in a system is effectively improved, the wettability and contact uniformity between the activator and base material particles are enhanced, and the geopolymer reaction is promoted to be more fully carried out. In addition, the film-forming ability of a geopolymer gel phase and the integrity of a three-dimensional network structure are improved, so that the compressive strength and the splitting strength of the pavement material are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering, and in particular to a full-solid waste geopolymer-stabilized desert sand pavement base material and a preparation method thereof. Background Art

[0002] In recent years, my country's highway construction has developed rapidly, with the country's total expressway mileage ranking first in the world. However, traditional pavement bases generally use cement-stabilized materials. The large-scale use of cement not only brings significant carbon emissions but also intensifies the pressure on mineral resource exploitation. At the same time, the fine aggregate used in large quantities during construction is mostly natural river sand. Its excessive exploitation has caused soil erosion and ecological damage, and there is an urgent need to optimize the selection of building materials and construction processes. Inner Mongolia is a major producer of solid waste materials such as fly ash and slag. These wastes contain a large amount of amorphous silicon-aluminum 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 and abundant reserves of desert sand. If it can be used as fine aggregate to replace river sand in pavement bases, it will not only solve the problem of material shortages but also provide new solutions for the design of pavement bases in arid desert areas.

[0003] In practical applications, the alkaline activator used in geopolymer systems has too high a viscosity and cannot be fully dispersed, resulting in low compressive strength and splitting tensile strength of the geopolymer-stabilized desert sand pavement base material. Therefore, a fully solid waste geopolymer-stabilized desert sand pavement base material with improved compressive and splitting tensile strengths and a preparation method thereof are needed. Summary of the Invention

[0004] In view of this, the present invention proposes a full-solid waste geopolymer stabilized desert sand pavement base material and a preparation method thereof, which can improve the 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 full-solid waste geopolymer-stabilized desert sand pavement base material, wherein the pavement base material includes desert sand, fly ash, slag and an alkali activator, and the alkali activator includes water glass, sodium hydroxide, water and sodium acrylate-acrylamide polymer.

[0006] By introducing a sodium acrylate-acrylamide polymer into existing alkaline activators (water glass, NaOH), this invention effectively improves the dispersion stability of the activator in the system, preventing localized over-concentration and precipitation. It also 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, significantly enhancing the material's early strength development and later mechanical properties, ultimately manifesting as significant increases in compressive strength and splitting strength.

[0007] Based on the above technical solution, preferably, the pavement base material includes, by weight, 1,700 parts of desert sand, 140-160 parts of fly ash, 140-160 parts of slag, 27-30 parts of water glass, 6-7 parts of sodium hydroxide, 165-180 parts of water, and 0.20-0.25 parts of sodium acrylate-acrylamide polymer.

[0008] On the basis of the above technical solution, preferably, the pavement base material further includes active silicon dioxide and nano-titanium dioxide.

[0009] Specifically, activated silica (white carbon black) can rapidly participate in the alkaline-induced reaction of the geopolymer, providing an additional silicon source and promoting the formation of NASH gel, thereby increasing the degree of reaction and early strength development. Furthermore, as a micro- and nano-scale filler, activated silica can effectively fill the pores between powder particles, optimize particle size distribution, and enhance the density of the matrix. Nano-titanium dioxide can further fill micropores and interfacial defects, enhancing the system's density. It can also promote the nucleation and growth of the gel phase through surface effects, improving the uniformity of the microstructure. The two have a significant synergistic effect: activated silica (white carbon black) focuses on chemical activity and micron-scale filling, while nano-titanium dioxide enhances physical filling and structural densification at the nanoscale. 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 cracking resistance.

[0010] On the basis of the above technical solution, preferably, the mass ratio of the desert sand, active silicon dioxide and nano-titanium dioxide is 1700:15-25:18-22.

[0011] On the basis of the above technical solution, preferably, the pavement base material further includes hollow glass microspheres and polypropylene fibers.

[0012] Specifically, hollow glass microspheres significantly improve the workability and fluidity of the mixture, promoting uniform dispersion of components and reducing internal porosity. Their fine particles can fill voids within the matrix, optimizing the particle packing structure and increasing the material's density and overall uniformity. Polypropylene fibers, through their three-dimensional, random distribution within the matrix, act as bridges to effectively inhibit the generation and propagation of microcracks, improving the material's tensile strength and toughness, and significantly enhancing its crack and splitting resistance. The two exhibit a significant synergistic effect: hollow glass microspheres improve the system's rheological properties, facilitating the uniform dispersion of polypropylene fibers within the matrix and preventing agglomeration, thereby fully realizing their reinforcing effect. Furthermore, the presence of the fibers constrains stress concentrations that may arise around the glass microspheres, preventing microcracks from propagating from the microbead interfaces. The two complement each other in improving density and crack resistance, achieving an organic combination of "micro-filling reinforcement" and "fiber crack resistance," collectively enhancing the comprehensive mechanical properties and durability of the pavement base material.

[0013] On the basis of the above technical solution, preferably, the particle size of the hollow glass microspheres is 25-35 μm, and the length of the polypropylene fibers is 5-8 mm.

[0014] On the basis of the above technical solution, preferably, the mass ratio of the desert sand, hollow glass microspheres and polypropylene fiber is 1700:8-12:3-5.

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

[0016] On the basis of the above technical solution, preferably, the active silicon dioxide is white carbon black.

[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: S1, preparation of an alkaline activator: adding water glass to water and stirring until dissolved, adding sodium hydroxide and stirring until dissolved, adding sodium acrylate-acrylamide polymer and stirring thoroughly to obtain an alkaline activator; S2, adding desert sand, nano-titanium dioxide, polypropylene fiber, hollow glass microspheres and the alkaline activator of step S1 into a blender and mixing them evenly, and then placing them in a sealed container and simmering for 1.5-2.5 hours; S3, evenly mixing the fly ash, slag and active silica, and then evenly stirring with the stewed material in step S2 to obtain a desert sand pavement base material.

[0018] Preferably, the modulus of the water glass in the alkali activator is 1.0.

[0019] Preferably, the dry density of the road base material is 1.835-1.920 g / cm 3 , and the water content is 9.60%-10.28%.

[0020] The full-solid-waste geopolymer stabilized desert sand road base material and the preparation method thereof have the following beneficial effects compared with the prior art: The sodium acrylate-acrylamide polymer is introduced into the alkali activator, which improves the dispersibility and reaction uniformity of the activator, and provides a good chemical environment for the full formation of the geopolymer gel. Further addition of active silicon dioxide (white carbon black) and nano titanium dioxide not only participates in the reaction with high activity, but also realizes multi-level filling in the micro-nano scale, significantly improves the matrix density and structural stability. Further, hollow glass microbeads and polypropylene fibers are introduced, the former improves the construction fluidity and assists in filling, and the latter provides crack resistance and toughening effect.

[0021] The three improved layers are progressive and mutually synergistic: the polymer ensures the uniform start of the activation reaction, the active components and nano fillers construct a dense gel structure basis, and the microbeads and fibers further optimize the physical structure and mechanical properties on this basis, realizing the whole-chain synergistic enhancement from "reaction promotion" to "structure strengthening" to "toughness improvement", and finally making the full-solid-waste geopolymer stabilized desert sand material have high strength, high toughness, durability and good construction performance. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0023] The fly ash used in the present application has a density of 2.55 g / cm 3 , an original water content of 0.6%, a SiO2 content of ≥43wt%, and an Al2O3 content of ≥23wt%. The slag powder has a density of 3.10 g / cm 3 , an original water content of 0.6wt%, a SiO 2 content of ≥34wt%, and a CaO content of ≥35wt%.

[0024] 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.

[0025] Table 1 Chemical composition and physical properties of fly ash and slag

[0026] Sodium hydroxide is commercially available flake sodium hydroxide with a mass percentage of 99%.

[0027] Water glass was purchased from Henan Shibang Chemical Company with a density of 1.51 g / cm 3 , the specific parameters are shown in Table 2.

[0028] Table 2 Physical and chemical indicators of water glass

[0029] Desert sand was collected from the Kubuqi Desert in Inner Mongolia Autonomous Region, with SiO2 content ≥76wt%, Al2O3 content ≥9.6wt%, particle size distribution within 0.075~0.3mm, and original moisture content <1%; Active silica (white carbon black) was purchased from Henan Jude Chemical Company with a purity of 99.99% and an average particle size of 1 μm.

[0030] Nano-titanium dioxide was purchased from Shanghai MacLean Reagent Co., Ltd.

[0031] Hollow glass microspheres were purchased from Henan Yixiang New Materials Co., Ltd. They were hollow spherical and had a particle size of 30 μm.

[0032] Sodium acrylate-acrylamide polymer with a purity of 90% was purchased from Guangdong Yuanfeng Chemical Reagent Co., Ltd.

[0033] The polypropylene fibers were flat and 6 mm in length and were purchased from Hebei Chuangsheng Building Materials and Chemical Co., Ltd.

[0034] The preparation method of the all-solid waste geopolymer stabilized desert sand pavement base of the present invention is based on the Chinese standard "Testing Procedure for Stabilized Materials with Inorganic Binders for Highway Engineering" (JTG 3441-2024), and the steps are as follows: S1. Maximum dry density and optimum moisture content test of geopolymer and different desert sands For different desert sand pavement base materials, different desert sands, fly ash, slag, activated silica, nano-titanium dioxide and polypropylene fiber were weighed according to the above-mentioned weight proportions and mixed evenly. Heavy compaction tests were carried out respectively according to the Chinese standard "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG 3441-2024), and the optimal moisture content and maximum dry density of the pavement base of different desert sands under these conditions were determined.

[0035] S2. Preparation of modified alkaline activator: The alkaline activator is prepared according to the optimal moisture content with 163-175 parts of water, 27-30 parts of water glass, 6-7 parts of sodium hydroxide and 0.20-0.25 parts of polyacrylamide-sodium acrylate copolymer.

[0036] The preparation process is to dissolve water glass in water and stir thoroughly to obtain a 10% concentration water glass solution. Then, solid sodium hydroxide particles are added to the 10% concentration water glass solution to adjust the modulus to 1.0; after thorough stirring to completely dissolve the sodium hydroxide, (polyacrylamide-sodium acrylate copolymer is added) and stirred thoroughly to obtain the (modified) alkaline activator.

[0037] S3, Stuffy Desert Sand: Weigh 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 alkaline activator using a blender (stir for 2 minutes), and place them in a black plastic bag and let them sit for 2 hours.

[0038] S4. Preparation of pavement base specimens: Mix 140-160 parts of fly ash, 140-160 parts of slag, and 15-25 parts of active silica, and stir evenly with the desert sand mixture prepared in S3. Calculate the weight of a single specimen based on the measured maximum dry density and optimum moisture content, and a compaction degree of 98%, according to the revised "Testing Procedures for Stabilized Materials with Inorganic Binders for Highway Engineering" (JTG 3441-2024). The revised formula is as follows: Standard mass of a single specimen: ; Where: V—specimen volume (cm 3 ), W Geo —Optimal moisture content of mixture (%), ρ max —Maximum dry density of the mixture (g / cm 3 ), γ—mixture compaction standard (%), m0—mixture mass (g), ρ 激发剂 —The density of the entire activator.

[0039] The density of the base activator is: ; Where: ρ 激发剂 —density of the activator as a whole, V—the volume of water required under the optimal moisture content of the material when stuffing, C—activator concentration, ρ 水 —density of water, ρ 水玻璃 —Density of water glass, m NaOH—The mass of NaOH required for a certain concentration and modulus, m bb —Mass of polyacrylamide-sodium acrylate copolymer.

[0040] Taking into account the mass loss during the specimen forming process, the mass of each specimen can be increased by 0~2% during the actual operation, that is: ; Where: —Finally determined mass, m0—mixture mass (g), δ—redundancy of calculated mixture mass (%) (value 1%).

[0041] Total mass of dry material (including dry soil and inorganic binder) for each specimen: ; In the formula: m1—mass of dry mixture (g), —The final determined mass, W Geo —Optimal moisture content of mixture (%), ρ 激发剂 —The density of the entire activator.

[0042] The mass of inorganic binder in each specimen: External doping method ; In the formula: m1 is the mass of dry mixture (g), m2 is the mass of inorganic binder (g), and α is the dosage of inorganic binder (%).

[0043] The mass of dry soil in each specimen: ; In the formula: m3 is the mass of dry soil (g), m1 is the mass of dry mixture (g), and m2 is the mass of inorganic binder (g).

[0044] Amount of water added to each specimen: ; Where: m w —water mass (g); m2—inorganic binder mass (g), m3—dry soil mass (g), W Geo —Optimal moisture content of mixture (%), ρ 激发剂 —The density of the entire activator.

[0045] Verification: ; Where: —Finally determined mass, m2—mass of inorganic binder (g), m3—mass of dry soil (g), m w —Mass of water added (g).

[0046] Example 1 The full solid waste geopolymer stabilized desert sand pavement base material of this example includes desert sand 1700g, fly ash 150g, slag 150g, water glass 29.36g, sodium hydroxide 6.63g, water 175.03g, and sodium acrylate-acrylamide polymer 0.2g.

[0047] The preparation method of the full solid waste geopolymer stabilized desert sand pavement base material includes the following steps: S1, preparation of alkali activator: dissolve water glass into water and stir well to obtain a 10% concentration water glass solution. Then add sodium hydroxide solid particles to the above-mentioned 10% concentration water glass solution to adjust the modulus to 1.0; after stirring well, make the sodium hydroxide completely dissolved, and finally add sodium acrylate-acrylamide polymer and stir well to obtain the alkali activator.

[0048] S2, mix desert sand and the alkali activator of step S1 in a blender and mix well, then place in a sealed container (black plastic bag) and steam for 2h; S3, mix fly ash and slag uniformly, then stir with the material steamed in step S2 to obtain the desert sand pavement base material.

[0049] Example 2 The full solid waste geopolymer stabilized desert sand pavement base material of this example includes desert sand 1700g, fly ash 150g, slag 150g, active silicon dioxide 20g, nano titanium dioxide 20g, water glass 28.19g, sodium hydroxide 6.37g, water 168.05g, and sodium acrylate-acrylamide polymer 0.2g.

[0050] The preparation method of the full solid waste geopolymer stabilized desert sand pavement base material includes the following steps: S1, preparation of alkali activator: dissolve water glass into water and stir well to obtain a 10% concentration water glass solution. Then add sodium hydroxide solid particles to the above-mentioned 10% concentration water glass solution to adjust the modulus to 1.0; after stirring well, make the sodium hydroxide completely dissolved, and finally add sodium acrylate-acrylamide polymer and stir well to obtain the alkali activator.

[0051] S2, mix desert sand, nano titanium dioxide, and the alkali activator of step S1 in a blender and mix well, then place in a sealed container (black plastic bag) and steam for 2h; S3, mix fly ash, slag, and active silicon dioxide uniformly, then stir with the material steamed in step S2 to obtain the desert sand pavement base material.

[0052] Example 3 The all-solid waste geopolymer-stabilized desert sand pavement base material of this embodiment includes 1700g of desert sand, 150g of fly ash, 150g of slag, 10g of hollow glass microspheres, 4g of polypropylene fiber, 20g of active silica, 20g of nano-titanium dioxide, 27.80g of water glass, 6.28g of sodium hydroxide, 165.71g of water and 0.2g of sodium acrylate-acrylamide polymer.

[0053] The method for preparing a fully solid waste geopolymer-stabilized desert sand pavement base material comprises the following steps: S1. Preparation of an alkaline activator: Dissolve water glass in water and stir thoroughly to obtain a 10% water glass solution. Then, add solid sodium hydroxide particles to the 10% water glass solution and adjust the modulus to 1.0; stir thoroughly to completely dissolve the sodium hydroxide. Finally, add sodium acrylate-acrylamide polymer and stir thoroughly to obtain an alkaline activator.

[0054] S2, adding desert sand, nano-titanium dioxide, polypropylene fiber, hollow glass microspheres and the alkaline activator of step S1 into a blender and mixing them evenly, and then placing them in a sealed container (black plastic bag) and stuffing them for 2 hours; S3, evenly mixing the fly ash, slag and active silica, and then evenly stirring with the stewed material in step S2 to obtain a desert sand pavement base material.

[0055] Example 4 The all-solid waste geopolymer-stabilized desert sand pavement base material of this embodiment includes 1700g of desert sand, 140g of fly ash, 160g of slag, 8g of hollow glass microspheres, 3g of polypropylene fiber, 15g of active silica, 18g of nano-titanium dioxide, 27.95g of water glass, 6.31g of sodium hydroxide, 166.61g of water and 0.25g of sodium acrylate-acrylamide polymer.

[0056] The method for preparing a fully solid waste geopolymer-stabilized desert sand pavement base material comprises the following steps: S1. Preparation of an alkaline activator: Dissolve water glass in water and stir thoroughly to obtain a 10% water glass solution. Then, add solid sodium hydroxide particles to the 10% water glass solution and adjust the modulus to 1.1; stir thoroughly to completely dissolve the sodium hydroxide. Finally, add sodium acrylate-acrylamide polymer and stir thoroughly to obtain an alkaline activator.

[0057] S2, adding desert sand, nano-titanium dioxide, polypropylene fiber, hollow glass microspheres and the alkaline activator of step S1 into a blender and mixing them evenly, and then placing them in a sealed container (black plastic bag) and stuffing them for 2 hours; S3, evenly mixing the fly ash, slag and active silica, and then evenly stirring with the stewed material in step S2 to obtain a desert sand pavement base material.

[0058] Example 5 The all-solid waste geopolymer-stabilized desert sand pavement base material of this embodiment includes 1700g of desert sand, 160g of fly ash, 140g of slag, 9g of hollow glass microspheres, 5g of polypropylene fiber, 25g of active silica, 19g of nano-titanium dioxide, 24.47g of water glass, 6.2g of sodium hydroxide, 163.75g of water and 0.22g of sodium acrylate-acrylamide polymer.

[0059] The method for preparing a fully solid waste geopolymer-stabilized desert sand pavement base material comprises the following steps: S1. Preparation of an alkaline activator: Dissolve water glass in water and stir thoroughly to obtain a 10% water glass solution. Then, add solid sodium hydroxide particles to the 10% water glass solution and adjust the modulus to 1; stir thoroughly until the sodium hydroxide is completely dissolved. Finally, add sodium acrylate-acrylamide polymer and stir thoroughly to obtain an alkaline activator.

[0060] S2, adding desert sand, nano-titanium dioxide, polypropylene fiber, hollow glass microspheres and the alkaline activator of step S1 into a blender and mixing them evenly, and then placing them in a sealed container (black plastic bag) and stuffing them for 2 hours; S3, evenly mixing the fly ash, slag and active silica, and then evenly stirring with the stewed material in step S2 to obtain a desert sand pavement base material.

[0061] Example 6 The all-solid waste geopolymer-stabilized desert sand pavement base material of this embodiment includes 1700g of desert sand, 150g of fly ash, 150g of slag, 12g of hollow glass microspheres, 4.5g of polypropylene fiber, 22g of active silica, 22g of nano-titanium dioxide, 27.38g of water glass, 6.18g of sodium hydroxide, 163.21g of water and 0.23g of sodium acrylate-acrylamide polymer.

[0062] The method for preparing a fully solid waste geopolymer-stabilized desert sand pavement base material comprises the following steps: S1. Preparation of an alkaline activator: Dissolve water glass in water and stir thoroughly to obtain a 10% water glass solution. Then, add solid sodium hydroxide particles to the 10% water glass solution and adjust the modulus to 1.0; stir thoroughly to completely dissolve the sodium hydroxide. Finally, add sodium acrylate-acrylamide polymer and stir thoroughly to obtain an alkaline activator.

[0063] S2, adding desert sand, nano-titanium dioxide, polypropylene fiber, hollow glass microspheres and the alkaline activator of step S1 into a blender and mixing them evenly, and then placing them in a sealed container (black plastic bag) and stuffing them for 2 hours; S3, evenly mixing the fly ash, slag and active silica, and then evenly stirring with the stewed material in step S2 to obtain a desert sand pavement base material.

[0064] Example 7 The difference between this embodiment and embodiment 1 is that active silicon dioxide and nano-titanium dioxide are added to the pavement base material, specifically: The all-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 active silica, 20g of nano-titanium dioxide, 30.23g of water glass, 6.99g of sodium hydroxide, 177.03g of water and 0.2g of sodium acrylate-acrylamide polymer.

[0065] The preparation method of the all-solid waste geopolymer-stabilized desert sand pavement base material is the same as that in Example 2.

[0066] Example 8 The difference between this embodiment and embodiment 7 is that hollow glass microspheres and polypropylene fibers are added to the pavement base material, specifically: The all-solid waste geopolymer-stabilized desert sand pavement base material of this embodiment includes 1700g of desert sand, 150g of fly ash, 150g of slag, 10g of hollow glass microspheres, 4g of polypropylene fiber, 20g of active silica, 20g of nano-titanium dioxide, 30.23g of water glass, 6.99g of sodium hydroxide, 177.03g of water and 0.2g of sodium acrylate-acrylamide polymer.

[0067] The preparation method of the all-solid waste geopolymer stabilized desert sand pavement base material is the same as that of Example 3: Comparative Example 1 Compared with Example 1, Comparative Example 1 lacks the sodium acrylate-acrylamide polymer, and the rest of the contents are the same as Example 1.

[0068] Comparative Example 2 Comparative Example 2 is compared with Example 2, except that nano titanium dioxide and sodium acrylate-acrylamide polymer are missing. At the same time, the amounts of water glass, sodium hydroxide and water are modified to 29.97 g, 6.78 g and 178.66 g according to the optimal water content. The rest of the contents are the same as in Example 2.

[0069] Comparative Example 3 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 are modified to 28.86 g, 6.52 g and 171.99 g according to the optimal water content. The rest of the contents are the same as Example 2.

[0070] Comparative Example 4 Comparative Example 4 is compared with Example 2, except that the sodium acrylate-acrylamide polymer is missing. At the same time, the amounts of water glass, sodium hydroxide and water are modified to 28.19 g, 6.37 g and 168.05 g according to the optimal water content. The rest of the contents are the same as in Example 2.

[0071] Comparative Example 5 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 are modified to 28.92g, 6.53g and 172.35g according to the optimal water content. The rest of the contents are the same as Example 3.

[0072] Comparative Example 6 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 are modified to 28.71g, 6.48g and 171.01g according to the optimal water content. The rest of the contents are the same as Example 3.

[0073] Comparative Example 7 Compared with Example 3, Comparative Example 7 lacks nano-titanium dioxide, active silicon dioxide and sodium acrylate-acrylamide polymer. At the same time, the amounts of water glass, sodium hydroxide and water are modified to 28.56g, 6.45g and 170.20g according to the optimal water content. The rest of the contents are the same as Example 3.

[0074] Comparative Example 8 Compared with Example 3, Comparative Example 8 lacks hollow glass microspheres and sodium acrylate-acrylamide polymer. At the same time, the amounts of water glass, sodium hydroxide and water are modified to 28.10 g, 6.34 g and 167.51 g according to the optimal water content. The rest of the contents are the same as Example 3.

[0075] Comparative Example 9 Compared with Example 3, Comparative Example 9 lacks sodium acrylate-acrylamide polymer, and the amounts of water glass, sodium hydroxide and water are modified to 27.80 g, 6.28 g and 165.71 g according to the optimal water content. The rest of the contents are the same as Example 3.

[0076] Comparative Example 10 Compared with Example 1, the content of sodium acrylate-acrylamide polymer in Comparative Example 10 exceeds the limit range, specifically 0.4, and the rest of the contents are the same as Example 1.

[0077] Comparative Example 11 Compared with Example 7, Comparative Example 11 lacks nano-titanium dioxide, and the rest of the contents are the same as Example 7.

[0078] Comparative Example 12 Compared with Example 8, Comparative Example 12 lacks hollow glass microspheres, and the rest of the contents are the same as Example 8.

[0079] Table 3 Composition of raw materials in Examples and Comparative Examples (g)

[0080] The pavement base materials prepared in the examples and comparative examples were poured into a 50mm cylindrical mold and prepared using a static pressure method to produce cylindrical specimens with a diameter of 50mm and a height of 50mm. Two hours after preparation, the specimens were demolded using a demolding machine, wrapped in plastic bags, and placed in a standard curing room for seven days to obtain all-solid waste geopolymer-stabilized desert sand pavement base specimens.

[0081] After seven days of curing, the specimens were removed from the curing room and immersed in deionized water for one day. Testing was conducted using an electro-hydraulic servo universal testing machine, with computer-controlled continuous uniform loading at a loading rate of 1 mm / min, as specified in the "Testing Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG 3441-2024). Six specimens were prepared for each group, and the results were calculated according to the requirements of the "Testing Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG 3441-2024).

[0082] Table 4 Compressive strength and splitting tensile strength of geopolymer-stabilized desert sand pavement base materials

[0083] As shown in Table 4, compared with Comparative Example 1, polyacrylamide-sodium acrylate copolymer is added to the activator of Example 1, which makes the activator better dispersed, increases the contact uniformity between the activator and the geopolymer powder, and thus improves the compressive strength and splitting strength.

[0084] Comparative Examples 1-3 show that the addition of activated silica increases the reactants in a disguised manner, improving the reactivity of the geopolymer powder and filling pores, thereby improving compressive strength and pit splitting performance. The addition of nano-titanium dioxide increases filler within the system, increasing overall density and filling pores, thereby improving compressive strength and splitting resistance. The addition of both activated silica and nano-titanium dioxide increases both reactants and fillers within the system, improving the reactivity of the geopolymer powder and further filling pores.

[0085] Comparative Example 1, as well as Comparative Examples 5-7, demonstrate that the addition of polypropylene fiber increases fine fillers within the system and blocks crack propagation paths, improving the tensile strength of the pavement base material while further filling pores. Therefore, compared to Comparative Example 1, Comparative Example 5 slightly improves compressive strength and significantly enhances pit splitting performance. The addition of hollow glass microspheres increases fine fillers within the system and improves its fluidity, resulting in a more uniform particle distribution within the system and further filling pores. Therefore, compared to Comparative Example 1, Comparative Example 6 improves compressive strength and significantly enhances pit splitting performance. The addition of polypropylene fiber and hollow glass microspheres increases fine fillers within the system, improving the tensile strength of the pavement base material. At the same time, the hollow glass microspheres enhance the uniformity of the system and the uniformity of the fibers within the system, thereby increasing its splitting strength.

[0086] Comparative Example 8 incorporates activated silica, nano-titanium dioxide, and polypropylene fibers, which increases the system's density by adding fine fillers and blocking crack propagation pathways, further enhancing the system's compressive and splitting resistance. Comparative Example 9, based on Comparative Example 8, adds polypropylene fibers, improving overall density and increasing tensile stress. Compared to Comparative Example 9, the addition of polyacrylamide-sodium acrylate copolymer to the activator of Example 3 makes the activator more uniform, thereby improving the system's compressive and tensile strengths.

[0087] From Comparative Example 10, it can be seen that when the added polyacrylamide-sodium acrylate copolymer exceeds the specified range, an overly dense polymer network will be formed in the system, hindering the free diffusion of alkali-excited ions, affecting the full progress of the geopolymer reaction, resulting in incomplete formation of the gel phase, and causing the density and internal bonding force of the material to decrease, thereby reducing both the compressive strength and tensile strength.

[0088] In summary, desert sand concrete Examples 3-6 can achieve a good dual improvement in compressive strength and splitting tensile properties, showing excellent comprehensive mechanical properties, and are a feasible proportioning path suitable for high-performance low-carbon concrete materials.

[0089] The above merely provides the preferred embodiment of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A fully solid waste geopolymer-stabilized desert sand pavement base material, characterized in that: The road base material comprises desert sand, fly ash, slag and an alkali activator, and the alkali activator comprises water glass, sodium hydroxide, water and sodium acrylate-acrylamide polymer.

2. The all-solid waste geopolymer stabilized desert sand pavement base material according to claim 1, characterized in that: Calculated by weight, the pavement base material includes 1700 parts of desert sand, 140-160 parts of fly ash, 140-160 parts of slag, 27-30 parts of water glass, 6-7 parts of sodium hydroxide, 163-175 parts of water and 0.20-0.25 parts of sodium acrylate-acrylamide polymer.

3. The all-solid waste geopolymer stabilized desert sand pavement base material according to claim 2, characterized in that: The road base material also includes active silicon dioxide and nano titanium dioxide.

4. The all-solid waste geopolymer stabilized desert sand pavement base material according to claim 3, characterized in that: The mass ratio of the desert sand, active silicon dioxide and nano titanium dioxide is 1700:15-25:18-22.

5. The all-solid waste geopolymer stabilized desert sand pavement base material according to claim 4, characterized in that: The road base material also includes hollow glass microspheres and polypropylene fibers.

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

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

8. The method for preparing a solid waste geopolymer-stabilized desert sand pavement base material according to claim 5, characterized in that: The following steps are involved: S1, preparation of an alkaline activator: adding water glass to water and stirring until dissolved, adding sodium hydroxide and stirring until dissolved, adding sodium acrylate-acrylamide polymer and stirring thoroughly to obtain an alkaline activator; S2, adding desert sand, nano-titanium dioxide, polypropylene fiber, hollow glass microspheres and the alkaline activator of step S1 into a blender and mixing them evenly, and then placing them in a sealed container and simmering for 1.5-2.5 hours; S3, evenly mixing the fly ash, slag and active silica, and then evenly stirring with the material prepared in step S2 to obtain a desert sand pavement base material.

9. The method for preparing a solid waste geopolymer-stabilized desert sand pavement base material according to claim 8, characterized in that: The modulus of the water glass in the alkali activator is 1.

0.

10. The method for preparing a solid waste geopolymer-stabilized desert sand pavement base material according to claim 8, characterized in that: The dry density of the pavement base material is 1.835-1.920 g / cm 3 , the moisture content is 9.60%-10.28%.

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