Pavement base mixture based on feldspar powder and preparation method thereof

Abstract

The invention provides a pavement base mixture based on feldspar powder and a preparation method thereof, and belongs to the technical field of road engineering materials. The pavement base mixture is prepared from the following raw materials: feldspar powder, cement, fly ash, low-liquid-limit clay and water. The feldspar powder is adopted to improve the strength and stability of the pavement base mixture. Meanwhile, the low-liquid-limit clay is added into the raw materials, so that the crack resistance and the deformation resistance of the pavement base mixture are improved. The raw material composition is adjusted, the addition amount of the feldspar powder is greatly increased, and meanwhile it is guaranteed that the mixture has good comprehensive performance.

Description

Technical Field

[0001] This invention relates to the field of road engineering materials technology, and in particular to a road base mixture based on feldspar powder and its preparation method. Background Technology

[0002] Feldspar powder is mainly used in the ceramics, glass, and enamel industries. With the increasing demand for lithium batteries from new energy vehicle companies, the production of feldspar powder far exceeds its consumption. How to dispose of this feldspar powder and avoid environmental pollution has become an urgent issue.

[0003] Using feldspar powder in building materials can consume large quantities of it.

[0004] For example, patent CN119707331A discloses an active feldspar powder, its preparation method, and its application in cement-stabilized crushed stone mixture. The active feldspar powder is obtained by calcining, coarsely grinding, and finely grinding feldspar powder, and then added to the cement mixture. The mixture includes 95.5 to 97.5 parts of aggregate, 2.5 to 3.5 parts of cement, and 0.5 to 1.0 parts of auxiliary cementitious material (active feldspar powder). Patent CN108503314A discloses a non-fired paving brick with added hydrophobic modified glass fiber. The raw materials include the following components: 10-15 parts of steel slag coarse aggregate, 40-50 parts of granite aggregate, 23-28 parts of cement, 20-25 parts of quartz sand, 10-16 parts of red mud, 3-6 parts of coal gangue powder, 4-7 parts of potassium feldspar powder, 7-10 parts of hydrophobic modified glass fiber, 1-3 parts of sealing and curing agent, 2-4 parts of water-reducing agent, and 25-30 parts of water.

[0005] In the aforementioned prior art, although feldspar powder is added to road surface materials, the resulting materials are all cement concrete and cannot be used to prepare cement-stabilized fine-grained soil.

[0006] Cement-stabilized fine-grained soil differs from cement concrete; they are two different materials used in road engineering. Cement-stabilized fine-grained soil is mainly used for the base or subbase of highways at all levels, especially suitable for areas lacking aggregate, and is more economical. Cement concrete, on the other hand, is widely used in pavement surface layers, bridges, culverts, and other structures requiring high load-bearing capacity and durability, directly bearing vehicle wear and environmental effects. The two differ in material composition, strength formation mechanism, and performance characteristics.

[0007] Cement concrete uses cement as a binder and ordinary sand and stone as aggregates, mixed with water according to the design mix ratio. It has a relatively high cement content (approximately 100-200 kg / m³ for lean concrete and even higher for ordinary concrete), and must include fine sand (0.15-4.75 mm) to fill voids. Through cement hydration, it forms a dense skeletal structure, resulting in high initial strength and rapid strength gain, with compressive strength reaching over 20 MPa and high flexural strength. Cement concrete also emphasizes workability (slump and other indicators), ensuring compaction through mixing, transportation, vibration, and curing. Strict control over gradation and water-cement ratio is crucial. It offers superior impermeability, frost resistance, and fatigue resistance, but it is brittle and less adaptable to temperature changes and load impacts.

[0008] Cement-stabilized fine-grained soil is made primarily of fine-grained soil (such as cohesive soil and silty soil), mixed with a small amount of cement (usually 4%~6%) and water. The content of particles with a maximum diameter less than 9.5mm and less than 2.36mm is not less than 90%. The strength of cement-stabilized fine-grained soil mainly depends on the cement's binding effect on soil particles and the compaction density after compaction. Strength increases slowly but continuously with age; the 7-day unconfined compressive strength is generally below 4.0MPa, and the tensile strength is low and prone to cracking. Strict control of compaction is required (93%~98% heavy compaction standard is required for the base layer). It is sensitive to moisture content during construction and must be compacted near the optimum moisture content, with soil clods crushed to ≤15mm. Cement-stabilized fine-grained soil exhibits a significant tendency for shrinkage cracking, relatively weak impermeability and frost resistance, and insufficient wear resistance when directly exposed to vehicle loads.

[0009] Given that feldspar powder has a similar particle size to fine-grained soil and lacks cementing properties, replacing part of the fine-grained soil with feldspar powder can effectively utilize stockpiled feldspar powder resources while reducing dependence on soil resources. Therefore, the main problem to be solved is to prepare a feldspar powder-based road base mixture (cement-stabilized fine-grained soil) and improve the overall performance of the mixture. Summary of the Invention

[0010] In view of this, the purpose of the present invention is to provide a road base mixture based on feldspar powder to solve the problem of feldspar powder accumulation, and at the same time to provide a road base material with excellent performance and low cost, which is suitable for the construction of base and subbase of secondary and lower highways.

[0011] To achieve the above objectives, the present invention provides the following technical solution:

[0012] A road base course mixture based on feldspar powder comprises the following raw materials in parts by weight:

[0013] The road base mixture contains 20-60 parts feldspar powder, 8-10 parts cement, 10-20 parts fly ash, and 10-80 parts low liquid limit clay. Water is also added to the road base mixture at the optimum moisture content of 8-20%.

[0014] Preferably, the feldspar powder is modified feldspar powder, and the preparation method of the modified feldspar powder includes the following steps:

[0015] Feldspar powder is calcined at 800-900℃ for 4-5 hours; then the pH of the ethanol-water mixture of silane coupling agent is adjusted to 4-5 with acetic acid, and the mixture is stirred and hydrolyzed for 10-30 minutes to obtain a modified solution; finally, the calcined feldspar powder is placed in the modified solution, stirred and mixed at 110-130℃ for 10-30 minutes, and dried to obtain modified feldspar powder.

[0016] More preferably, the feldspar powder comprises the following components by weight percentage:

[0017] The composition is 70%-80% SiO2, 15%-25% Al2O3, 3%-5% Na2O, 3%-5% K2O, with the balance being unavoidable impurities.

[0018] Preferably, the cement is P·O42.5 ordinary Portland cement.

[0019] Preferably, the low liquid limit clay has a liquid limit of 40%-43%, a plastic limit of 20%-25%, a plasticity index of 20-22, a moisture content of 10%-15%, and a dry density of 1.5-1.8 g / cm³. 3 .

[0020] Another object of the present invention is to provide a method for preparing a road base course mixture based on feldspar powder, comprising the following steps:

[0021] S1. Raw material preparation: Weigh the feldspar powder, cement, fly ash, low liquid limit clay, and water according to the stated weight proportions;

[0022] S2. Dry mixing: Weigh the feldspar powder, fly ash, cement and low liquid limit clay into the mixer and dry mix until they are evenly mixed to obtain a dry mixture;

[0023] S3. Wet mixing and molding: Water is added to the dry mixture and the mixture is stirred until homogeneous to obtain the road base mixture;

[0024] S4. Compaction and curing: The road base mixture is spread, compacted and cured to obtain the road base mixture.

[0025] Preferably, the compaction in step S4 is performed using a static pressure method with a pressure of 1-5 MPa.

[0026] Preferably, the maintenance method described in step S4 is to maintain the product in an environment of 20±2℃ and ≥95% humidity for 6 days, then immerse it in water for 1 day, and finally maintain it naturally.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention provides a road base course mixture based on feldspar powder and its preparation method. The mixture uses feldspar powder as the main raw material, achieving high-value-added resource utilization of solid waste. This invention modifies and activates the feldspar powder by calcining to remove organic impurities and disrupt its inert surface structure. Then, surfactants are used to improve the surface properties and binding performance of the feldspar powder, enhancing its dispersion performance and thus improving the strength and stability of the road base course mixture. Simultaneously, low-liquid-limit clay is added to the raw materials in this application, adjusting the raw material composition and significantly increasing the amount of feldspar powder added, while ensuring the mixture has excellent overall performance. Detailed Implementation

[0029] This invention provides a road base mixture based on feldspar powder, which is composed of the following raw materials in parts by weight:

[0030] The road base mixture contains 20-60 parts feldspar powder, 8-10 parts cement, 10-20 parts fly ash, and 10-80 parts low liquid limit clay. Water is also added to the road base mixture at the optimum moisture content of 8-20%.

[0031] Preferably, the water is added at the optimal moisture content of the road base mixture, which is 9.5-15.8%.

[0032] The feldspar powder is either commercially available feldspar powder or modified feldspar powder.

[0033] In a specific embodiment of the present invention, the preparation method of the modified feldspar powder includes the following steps:

[0034] Feldspar powder was calcined at 800℃ for 4.5 hours; then the pH of the ethanol-water mixture of silane coupling agent was adjusted to 5 with acetic acid, and the mixture was stirred and hydrolyzed for 30 minutes to obtain a modified solution; finally, the calcined feldspar powder was placed in the modified solution at a ratio of 1 kg: 2 L, stirred and mixed at 110℃ for 20 minutes, and dried to obtain modified feldspar powder with a moisture content of 7%.

[0035] In a specific embodiment of the present invention, the feldspar powder is taken from the tailings of the Yichun lithium mine in Jiangxi Province, and its specific composition is as follows: SiO2 74.25%, Al2O3 15.63%, Na2O 4.14%, K2O 4.07%, with the balance being unavoidable impurities.

[0036] In a specific embodiment of the present invention, the cement is P·O42.5 ordinary Portland cement.

[0037] In a specific embodiment of the present invention, the low liquid limit clay has a liquid limit of 42.02%, a plastic limit of 20.99%, a plasticity index of 21.03, a moisture content of 14.5%, and a dry density of 1.71 g / cm³. 3 .

[0038] The preparation method of the feldspar powder-based road base mixture includes the following steps:

[0039] S1. Raw material preparation: Weigh the feldspar powder, cement, fly ash, low liquid limit clay, and water according to the stated weight proportions;

[0040] S2. Dry mixing: Weigh the feldspar powder, fly ash, cement and low liquid limit clay into the mixer and dry mix until they are evenly mixed to obtain a dry mixture;

[0041] S3. Wet mixing and molding: Water is added to the dry mixture and the mixture is stirred until homogeneous to obtain the road base mixture;

[0042] S4. Compaction and curing: The road base mixture is spread, compacted and cured to obtain the road base mixture.

[0043] In a specific embodiment of the present invention, the compaction is carried out by static pressure method with a pressure of 1.5 MPa; the curing method is to cure for 6 days in an environment of 20±2℃ and humidity ≥95%, then immerse in water for the last day, and then cure naturally for 28 days.

[0044] The present invention will be further described below with reference to the embodiments.

[0045] Example 1

[0046] A road base course mixture based on feldspar powder, comprising the following raw materials in parts by weight:

[0047] 40 parts modified feldspar powder, 10 parts cement, 10 parts fly ash, and 10 parts low liquid limit clay were mixed with water at the optimum moisture content of 9.5% for road base mixture.

[0048] The preparation method of the modified feldspar powder includes the following steps:

[0049] Feldspar powder was calcined at 800℃ for 4.5 hours; then the pH of the ethanol-water mixture of silane coupling agent was adjusted to 5 with acetic acid, and the mixture was stirred and hydrolyzed for 30 minutes to obtain a modified solution; finally, the calcined feldspar powder was placed in the modified solution at a ratio of 1 kg: 2 L, stirred and mixed at 110℃ for 20 minutes, and dried to obtain modified feldspar powder with a moisture content of 7%.

[0050] The preparation method of the feldspar powder-based road base mixture includes the following steps:

[0051] S1. Raw material preparation: Weigh the modified feldspar powder, cement, fly ash, low liquid limit clay, and water according to the specified weight proportions.

[0052] S2. Dry mixing: Weigh the modified feldspar powder, fly ash, cement and low liquid limit clay into the mixer and dry mix until they are evenly mixed to obtain a dry mixture;

[0053] S3. Wet mixing and molding: Water is added to the dry mixture and the mixture is stirred until homogeneous to obtain the road base mixture;

[0054] S4. Compaction and curing: The road base mixture is spread, compacted and cured to obtain the road base mixture.

[0055] Example 2

[0056] A road base course mixture based on feldspar powder, comprising the following raw materials in parts by weight:

[0057] 50 parts modified feldspar powder, 10 parts cement, 15 parts fly ash, and 15 parts low liquid limit clay were mixed with water at the optimum moisture content of 11.5% for road base mixture.

[0058] The specific raw materials and preparation methods are the same as in Example 1.

[0059] Example 3

[0060] A road base course mixture based on feldspar powder, comprising the following raw materials in parts by weight:

[0061] 60 parts modified feldspar powder, 9 parts cement, 17 parts fly ash, and 20 parts low liquid limit clay were mixed with water at the optimum moisture content of 15.8% for road base mixture.

[0062] The specific raw materials and preparation methods are the same as in Example 1.

[0063] Example 4

[0064] A road base mixture based on feldspar powder, with the same raw material composition and preparation method as in Example 1, except that the feldspar powder in Example 4 is not modified.

[0065] Example 5

[0066] A road base mixture based on feldspar powder, with the same raw material composition and preparation method as in Example 2, except that the feldspar powder in Example 5 is not modified.

[0067] Comparative Example 1

[0068] A road base course mixture based on feldspar powder, with the same raw material composition and preparation method as in Example 1, differing only in the preparation method of the modified feldspar powder in Comparative Example 1, the steps of which are as follows:

[0069] The pH of the ethanol-water mixture of silane coupling agent was adjusted to 5 with acetic acid, and the mixture was stirred and hydrolyzed for 30 minutes to obtain a modified solution. Finally, feldspar powder was placed in the modified solution at a ratio of 1 kg: 2 L, stirred and mixed at 110 °C for 20 minutes, and dried to obtain modified feldspar powder.

[0070] Comparative Example 2

[0071] A road base mixture based on feldspar powder, with the same raw material composition and preparation method as in Example 1, differing only in the preparation method of the modified feldspar powder in Comparative Example 2, the steps of which are as follows:

[0072] Modified feldspar powder was obtained by calcining feldspar powder at 800℃ for 4.5 hours.

[0073] Comparative Example 3

[0074] A road base mixture based on feldspar powder, with the same raw material composition and preparation method as in Example 1, differing only in the preparation method of the modified feldspar powder in Comparative Example 3, the steps of which are as follows:

[0075] After soaking the feldspar powder in a mixed solution of sodium carbonate and potassium permanganate for 1 hour, it was removed and dried. Then, 2% of the weight of the feldspar powder, silane coupling agent KH550, 1% of the weight of the feldspar powder, sodium lauryl sulfate, and 3% of the weight of the feldspar powder were added. The mixture was stirred at 400 r / min for 15 minutes and then ground. The modified feldspar powder was obtained by passing it through a 150-mesh sieve.

[0076] Comparative Example 4

[0077] A road base mixture based on feldspar powder, with the same raw material composition and preparation method as in Example 1, except that feldspar powder is not added in Comparative Example 4.

[0078] The performance of the above-mentioned base course mixture was tested in accordance with the "Test Procedure for Inorganic Binder Stabilized Materials in Highway Engineering" (JTG 3441—2024) and the "Technical Specifications for Construction of Pavement Base Course in Highway Engineering" (JTG / T F20-2015). The test results are shown in Table 1.

[0079] Table 1

[0080]

[0081] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A road base mixture based on feldspar powder, characterized in that, Including the following parts by weight of raw materials: The road base mixture contains 20-60 parts feldspar powder, 8-10 parts cement, 10-20 parts fly ash, and 10-80 parts low liquid limit clay. Water is also added to the road base mixture at the optimum moisture content of 8-20%.

2. The road base mixture based on feldspar powder according to claim 1, characterized in that, The feldspar powder is modified feldspar powder, and the preparation method of the modified feldspar powder includes the following steps: Feldspar powder is calcined at 800-900℃ for 4-5 hours; then the pH of the ethanol-water mixture of silane coupling agent is adjusted to 4-5 with acetic acid, and the mixture is stirred and hydrolyzed for 10-30 minutes to obtain a modified solution; finally, the calcined feldspar powder is placed in the modified solution, stirred and mixed at 110-130℃ for 10-30 minutes, and dried to obtain modified feldspar powder.

3. The road base mixture based on feldspar powder according to claim 2, characterized in that, The feldspar powder comprises the following components by weight percentage: The composition is 70%-80% SiO2, 15%-25% Al2O3, 3%-5% Na2O, 3%-5% K2O, with the balance being unavoidable impurities.

4. The road base mixture based on feldspar powder according to claim 1, characterized in that, The cement is P·O42.5 ordinary Portland cement.

5. The road base mixture based on feldspar powder according to claim 1, characterized in that, The low liquid limit clay has a liquid limit of 40%-43%, a plastic limit of 20%-25%, a plasticity index of 20-22, a moisture content of 10%-15%, and a dry density of 1.5-1.8 g / cm³. 3 .

6. The method for preparing road base mixture based on feldspar powder according to claim 1, characterized in that, Includes the following steps: S1. Raw material preparation: Weigh the feldspar powder, cement, fly ash, low liquid limit clay, and water according to the stated weight proportions; S2. Dry mixing: Weigh the feldspar powder, fly ash, cement and low liquid limit clay into the mixer and dry mix until they are evenly mixed to obtain a dry mixture; S3. Wet mixing and molding: Water is added to the dry mixture and the mixture is stirred until homogeneous to obtain the road base mixture; S4. Compaction and curing: The road base mixture is spread, compacted and cured to obtain the road base mixture.

7. The method for preparing road base course mixture based on feldspar powder according to claim 6, characterized in that, The compaction in step S4 is performed using the static pressure method, with a pressure of 1-5 MPa.

8. The method for preparing road base mixture based on feldspar powder according to claim 6, characterized in that, The maintenance method described in step S4 is to maintain the product in an environment of 20±2℃ and ≥95% humidity for 6 days, then immerse it in water for 1 day, and finally maintain it naturally.

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