Rubber fiber particles capable of improving mechanical properties of soil and preparation method of rubber fiber particles

Abstract

The invention discloses rubber fiber particles capable of improving the mechanical property of a soil body and a preparation method of the rubber fiber particles. The rubber fiber particles are composite fiber material particles of rock fibers, rubber and TPU. The rubber fiber particles provided by the invention can form fiber rubber-sand mixed soil by being doped with sandy soil, so that the mechanical property of a building material is improved. The TPU material is used for hot melt bonding of the rubber particles and the fiber material to form an integral material, the fiber rubber particles can improve the bearing capacity and shear strength of the mixed soil, and meanwhile, the integrity of a soil body can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, and in particular to rubber fiber particles capable of improving the mechanical properties of soil and a preparation method thereof. Background Art

[0002] At present, the annual output of waste tires in China is as high as more than 10,000 tons. The common treatment methods for waste tires are stockpiling, incineration and landfill, which cause great irreversible damage to the environment. In response to the global call for energy conservation and emission reduction and green, low-carbon and environmental protection, the treatment of waste tires has become more and more diversified. In the field of construction engineering, because rubber particles have low density, good elasticity and hydrophobicity, they can be mixed with soil to achieve good shock isolation and vibration reduction effects, and can also effectively control the liquefaction of sandy soil and silt. They are often used as backfill materials for roadbeds, pipelines, and retaining walls. However, while the damping ratio of rubber-mixed soil increases, its shear strength decreases, and the soil layer is severely damaged by shear.

[0003] Relevant research has found that adding an appropriate amount of fiber to the rubber mixed soil can form a bond between the mixed soil particles in a certain dense state, so that when the soil is sheared, the fiber can provide reverse tension, thereby enhancing the overall shear strength of the mixed soil. However, when the fiber and rubber particles are mixed in the soil, there will be uneven mixing, fiber agglomeration, and the fiber and rubber particles are not evenly distributed in the same soil layer, which will lead to an increase in the shear strength of the mixed soil in the local soil layer, while the shear strength of the soil layer with increased damping ratio is not improved. The above-mentioned problem is caused by the fact that there is no adhesion between the fiber and the rubber particles, and the general mixing method of the mixed soil is wet mixing. During the mixing process, the fiber is easy to get wet and agglomerated, resulting in the fiber and rubber particles not being evenly distributed in the soil layer at the same depth. This will lead to the shear strength of the mixed soil in the part where the fiber is agglomerated. The integrity cannot be improved. Summary of the invention

[0004] In order to improve the seismic performance of roadbed soil or the anti-liquefaction ability of sand in the field of engineering construction, the dynamic characteristics of the soil are improved by adding a proper amount of rubber particles with a reasonable particle size. The present invention provides a rubber fiber particle capable of improving the mechanical properties of the soil and a preparation method thereof. In view of the problems in the background technology, the chemical fiber and the rubber particle are directly integrated through technical improvement, so that the overall shear strength is improved while ensuring the improvement of the damping ratio.

[0005] To achieve the above purpose, the technical solution provided by the present invention is:

[0006] The first aspect of the present application provides a mold for preparing rubber fiber particles, including a base plate and an upper pressing plate that can cover and be fixed on the base plate; the upper inner surface of the base plate is provided with a plurality of first grooves, and the lower inner surface of the upper pressing plate is provided with a plurality of second grooves corresponding to the first grooves, and the first grooves and the second grooves constitute a rubber fiber particle molding space; the upper pressing plate is connected to a heating device, and the heating device can heat the upper pressing plate; the upper pressing plate is provided with a plurality of material guiding heating holes, and each material guiding heating hole corresponds to and is connected to the position of the first groove.

[0007] The first groove and the second groove are both hemispherical.

[0008] The inner diameters of the first groove and the second groove are 4-6 mm.

[0009] The second aspect of the present application provides a method for preparing rubber fiber particles capable of improving the mechanical properties of soil, comprising the following steps:

[0010] Using the mold for preparing rubber fiber particles as described above, place rock fiber into the first groove of the bottom plate;

[0011] Place rubber powder in the groove where the rock fiber has been placed;

[0012] Put the upper pressing plate on the bottom plate to fix the bottom plate and the upper pressing plate;

[0013] Turn on the heating device and heat the upper platen to 150-200 degrees;

[0014] Pour TPU powder into the material guide heating hole of the upper pressing plate. After 10-15 minutes, when the powder in the hole is heated into liquid and flows into the molding space formed by the first groove and the second groove, open the upper pressing plate.

[0015] Allowing the mixture in the molding space to cool naturally to room temperature to obtain a composite fiber material;

[0016] The composite fiber material in the mold is taken out and shredded to obtain rubber fiber particles that can improve the mechanical properties of the soil.

[0017] The inner surfaces of the bottom plate and the upper pressing plate of the mold for preparing rubber fiber particles are wiped clean before use, and lubricant is applied to the inner surfaces to facilitate later demoulding.

[0018] The rock fiber is at least one of basalt fiber, glass fiber and carbon fiber.

[0019] The size parameter of the rock fiber is 40±0.2 cm; the particle size of the rubber powder is 0.5-1 mm; after the composite fiber material in the mold is taken out, the size parameter of the shredded material is 2.5-4.5 cm.

[0020] The mass ratio of rock fiber to rubber powder and TPU powder is 1-3:7-9:1, preferably 1:9:1; the total amount of rock fiber and rubber powder placed in each first groove of the bottom plate is 10±0.1g.

[0021] The third aspect of the present application provides a rubber fiber particle, wherein the rubber fiber particle is a composite fiber material particle of rock fiber, rubber and TPU.

[0022] The fourth aspect of the present application provides a method for improving the mechanical properties of soil, wherein the rubber fiber particles are mixed with pure sand to form a fiber rubber-sand mixed soil, wherein the doping amount of the rubber fiber particles is 5% to 20%, preferably 11%.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The rubber fiber particles of the present invention can be mixed with sand to form a fiber rubber-sand mixed soil, thereby improving the mechanical properties of the building material. Compared with pure sand and rubber-sand mixed soil, the fiber rubber-sand mixed soil of the present invention has a higher bearing capacity and a better shock absorption effect; and due to the effect of the fibers, the fiber rubber-sand mixed soil has a higher shear strength and also improves the integrity of the soil.

[0025] Dense pure sand is superior to clay roadbed in roadbed filling, but due to the influence of pore water pressure, sand liquefaction is prone to occur. Traditional rubber-sand mixed soil has a certain effect on anti-liquefaction ability because it is mixed with highly hydrophobic rubber particles in the sand, but the shear strength is reduced by the addition of rubber particles, and the service life of the roadbed is greatly reduced.

[0026] Through research, the present invention finds that by utilizing the "rebar implantation" principle and adding fiber materials into rubber-sand mixed soil, the shear strength of the mixed soil can be improved. However, since fibers are easily agglomerated and unevenly layered during the mixing process of the fibers and the rubber-sand mixed soil, the shear strength of the fiber-rubber-sand mixed soil cannot be fully exerted. Therefore, the fiber-rubber-sand mixed soil of the present invention improves the original method of directly adding and mixing materials, and adopts TPU material to hot-melt bond the rubber particles and the fiber material, so that the fiber-rubber particles form a whole, thereby improving the bearing capacity and shear strength of the mixed soil, and at the same time improving the integrity of the soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 : A schematic structural diagram of a bottom plate of a mold for preparing rubber fiber particles of the present invention.

[0028] Figure 2 : A schematic structural diagram of an upper pressing plate of a mold for preparing rubber fiber particles of the present invention.

[0029] Figure 3 : A schematic structural diagram of the assembly of an upper pressing plate and a bottom plate of a mold for preparing rubber fiber particles of the present invention.

[0030] Figure 4 : A schematic diagram of the three-dimensional structure of the upper pressing plate and the bottom plate of the mold for preparing rubber fiber particles of the present invention.

[0031] Figure 5 : Schematic diagram of the preparation method of rubber fiber particles of the present invention.

[0032] Figure 6 : Schematic diagram of TPU material.

[0033] Figure 7 : Schematic diagram of the rubber fiber particles of the present invention.

[0034] Figure 8 : Damping ratio curves of three samples under confining pressure of 100KPa in the embodiment.

[0035] Fig. 9 : Dynamic shear modulus curves of three samples under confining pressure of 100KPa in the embodiment.

[0036] Fig.10 : Bearing ratio variation diagram of three kinds of samples at different ages under confining pressure of 100KPa in the embodiment.

[0037] In the figure: 1-upper pressing plate, 2-material guiding and heating hole, 3-heating device, 4-molding space, 5-bottom plate. DETAILED DESCRIPTION

[0038] The above contents of the present invention are further described in detail below in the form of embodiments, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the above contents of the present invention belong to the scope of the present invention.

[0039] The experimental methods used in the following examples are all conventional methods unless otherwise specified, and the reagents, methods and equipment used are all conventional reagents, methods and equipment in the technical field unless otherwise specified.

[0040] For the sake of simplicity, this document only specifically discloses some numerical values ​​and optional ranges. However, any lower limit can be combined with any upper limit to form an unambiguous range; and any lower limit can be combined with other lower limits to form an unambiguous range. Similarly, any upper limit can be combined with any other upper limit to form an unambiguous range; the optional items in the optional range can also be combined arbitrarily.

[0041] Unless otherwise specified, the terms used in this application have the commonly known meanings generally understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art.

[0042] The present application provides a mold for preparing rubber fiber particles, including a base plate 5 and an upper pressing plate 1 that can cover and be fixed on the base plate 5; a plurality of first grooves are provided on the upper inner surface of the base plate 5, and a plurality of second grooves corresponding to the first grooves are provided on the lower inner surface of the upper pressing plate 1, and the first grooves and the second grooves constitute a rubber fiber particle molding space; the upper pressing plate 1 is connected to a heating device 3, and the heating device 3 can heat the upper pressing plate 1; a plurality of material guiding heating holes 2 are provided on the upper pressing plate 1, and each material guiding heating hole 2 corresponds to the position of the first groove and is connected.

[0043] The first groove and the second groove are both hemispherical, and the inner diameters of the first groove and the second groove are 4-6 mm.

[0044] In the embodiment, the upper pressing plate 1 is made of an aluminum plate, and the heating device 3 is a PTC heating guide plate.

[0045] The present application also provides a method for preparing rubber fiber particles capable of improving the mechanical properties of soil, comprising the following steps:

[0046] Using the mold for preparing rubber fiber particles, place rock fiber into the first groove of the bottom plate 5;

[0047] Place rubber powder in the groove where the rock fiber has been placed;

[0048] Cover the upper pressing plate 1 on the bottom plate 5, and fix the bottom plate 5 and the upper pressing plate 1;

[0049] Turn on the heating device 3 to heat the upper pressing plate 1 to 150-200 degrees;

[0050] Pour TPU powder into the material guide heating hole 2 of the upper pressing plate 1. After 10-15 minutes, when the powder in the hole is heated into liquid and flows into the molding space 4 formed by the first groove and the second groove, the upper pressing plate 1 is opened;

[0051] Allowing the mixture in the molding space 4 to cool naturally to room temperature to obtain a composite fiber material;

[0052] The composite fiber material in the mold is taken out and shredded to obtain rubber fiber particles that can improve the mechanical properties of the soil.

[0053] The inner surfaces of the mold bottom plate 5 and the upper pressing plate 1 for preparing rubber fiber particles are wiped clean before use, and a small amount of vaseline is applied to the inner surfaces to facilitate later demoulding.

[0054] In some embodiments, the rock fiber is at least one of basalt fiber, glass fiber, and carbon fiber.

[0055] The size parameter of the rock fiber is 40±0.2 cm; after the composite fiber material in the mold is taken out, the size parameter of the shredded material is 3±0.2 cm.

[0056] The mass ratio of rock fiber to rubber powder and TPU powder is 1-3:7-9:1; the total amount of rock fiber and rubber powder placed in each first groove of the bottom plate 5 is 10±0.1g.

[0057] The present application also provides a rubber fiber particle, which is a composite fiber material particle of rock fiber, rubber and TPU.

[0058] The present application also provides a method for improving the mechanical properties of soil, wherein rubber fiber particles are mixed with pure sand, and the doping amount of the rubber fiber particles in the pure sand is 5% to 20%.

[0059] The present invention is further described in detail below in conjunction with specific embodiments:

[0060] A new type of rubber fiber particles capable of comprehensively enhancing seismic performance and shear strength, the preparation method comprising the following steps:

[0061] 1. Place the customized base plate 5 mold (see Figure 1 ) Wipe the surface clean and apply a small amount of vaseline on the surface to facilitate demoulding later; wherein the first groove and the second groove are both hemispherical; the inner diameter of the first groove and the second groove is 5mm;

[0062] 2. Place the basalt fiber into the groove of the bottom plate 5 according to the length and width of the mold. The size parameter of the rock fiber is 40±0.2cm, and spread an appropriate amount of rubber powder on the first groove. The particle size of the rubber powder used is: 0.5-0.7mm;

[0063] 3. Apply a proper amount of vaseline to the contact surface of the upper pressing plate 1, align the holes, fix the upper and lower plates, and introduce a proper amount of rubber powder through the material guide and heating hole 2 to fill the second groove with rubber powder;

[0064] 4. Pour an appropriate amount of TPU powder into the material guide heating hole 2 of the upper pressing plate 1, and turn on the PTC heating plates on the left and right sides of the upper pressing plate 1 to heat the upper pressing plate 1 to a temperature of 180 degrees. After 12 minutes, when the powder in the hole melts into liquid and flows into the bottom plate 5 mold, stop heating, let the aluminum plate cool to room temperature, and then loosen the upper and lower plates;

[0065] 5. Use a crushing tool to cut the formed composite fiber material into particles, namely rubber fiber particles. The size parameter of the cut particles is 2.5 to 4.5 cm. The cut particles are cut so that the length of the fiber extending out of the particle end is about 1 to 2 cm. Figure 5 , Figure 7 shown.

[0066] The rubber fiber particles of the following examples were prepared by adopting this step, and pure sand was added to form a fiber rubber-sand mixed soil.

[0067] Embodiment 1:

[0068] The rubber fiber particles are prepared by the above specific preparation method, wherein the mass ratio of rock fiber to rubber powder and TPU powder is 1:9:1;

[0069] The rubber fiber particles are mixed with pure sand to form a fiber rubber-sand mixed soil, in which the mixing amount of the rubber fiber particles is 11%.

[0070] Embodiment 2:

[0071] The rubber fiber particles are prepared by the above specific method, wherein the mass ratio of rock fiber to rubber powder and TPU powder is 2:8:1.

[0072] The rubber fiber particles are mixed with pure sand to form a fiber rubber-sand mixed soil, in which the mixing amount of the rubber fiber particles is the same as that in Example 1.

[0073] Embodiment 3:

[0074] The rubber fiber particles are prepared by the above specific method, wherein the mass ratio of rock fiber to rubber powder and TPU powder is 3:7:1.

[0075] The rubber fiber particles are mixed with pure sand to form a fiber rubber-sand mixed soil, in which the mixing amount of the rubber fiber particles is the same as that in Example 1.

[0076] Embodiment 4:

[0077] It is basically the same as Example 1, except that the rubber fiber particles prepared in Example 1 are mixed with pure sand to form a fiber rubber-sand mixed soil, wherein the mixing amount of the rubber fiber particles is 9%.

[0078] Embodiment 5:

[0079] It is basically the same as Example 1, except that the rubber fiber particles prepared in Example 1 are mixed with pure sand to form a fiber rubber-sand mixed soil, wherein the mixing amount of the rubber fiber particles is 13%.

[0080] Comparative Example 1:

[0081] Instead of using the above mold, pure sand is used.

[0082] Comparative Example 2:

[0083] Without using the above mold, the rubber particles are directly mixed with pure sand to form a rubber-sand mixed soil, in which the mixing amount of rubber fiber particles is 10%.

[0084] The above embodiments and examples have been tested and the data are shown in Table 1.

[0085]

[0086] The test results show that:

[0087] Under the same fiber rubber particle doping amount but different doping mass ratio, as the doping amount of rubber particles decreases, its damping ratio also decreases, but its dynamic shear modulus does not increase significantly due to the increase in fiber doping. The reason is that from a microscopic analysis, the increase in fibers around the unit will increase the pores between soil particles and fiber rubber particles, which has little effect on the dynamic shear modulus of soil samples. The mass ratio of rock fiber to rubber powder and TPU powder is preferably 1:9:1; under the same doping mass ratio but different fiber rubber particle doping amount, as the fiber rubber particle doping amount increases, the damping ratio will increase, while its dynamic shear modulus will increase first and then decrease, and the optimal value is when the fiber rubber particle doping amount is 11%; although the bearing ratio of fiber rubber particle mixed soil increases with the increase in fiber content, it also decreases due to the increase in rubber content. Compared with pure sand and rubber sand, fiber rubber sand can enhance the damping ratio of soil and improve the dynamic shear modulus of soil.

[0088] The following is a further in-depth study of the solutions of Example 1, Comparative Example 1, and Comparative Example 2:

[0089] The dynamic parameters of rubber mixed soil mainly include dynamic shear modulus and damping ratio. The dynamic shear modulus reflects the ratio of shear stress to shear strain of rubber mixed soil under dynamic load, while the damping ratio is a measure of the ability of rubber mixed soil to absorb dynamic load energy, which can play the role of shock absorption and vibration isolation.

[0090] California bearing ratio (CBR) is a test method proposed by the state of California to evaluate the bearing capacity of base materials. The bearing capacity is characterized by the ability of the material to resist local load pressure deformation, and the bearing capacity of standard crushed stone is used as the standard. The CBR value is expressed as a percentage of the relative value. The higher the CBR value, the stronger the bearing capacity of the roadbed, and the smaller the settlement and deformation of the roadbed.

[0091] A large number of experimental studies by domestic and foreign scholars have shown that the confining pressure σ3, rubber content Rc, and fiber content Fc will affect the dynamic shear modulus, damping ratio, and CBR value of rubber mixed soil. Fujian standard sand was used as the research object, and the preparation method of the present application was used to study the pure sand of Comparative Example 1, the pure sand of Comparative Example 2 mixed with rubber particles (Rc = 10%), and the pure sand of Example 1 mixed with rubber particles and fibers (Rc = 10%, Fc = 1%), and conduct relevant tests under the confining pressure σ3 = 100KPa.

[0092] Wherein, Rc represents the mass ratio of rubber mixed in the mixed sand to the total sample, and Fc represents the mass ratio of fiber mixed in the mixed sand to the total sample.

[0093] Figure 8 The damping ratio curves of three samples under confining pressure of 100KPa are shown in Figure 2. The test results show that under confining pressure of 100KPa, the damping ratios of rubber-sand mixture (Rc=10%) and fiber rubber-sand mixture (Rc=10%, Fc=1%) are basically similar, but both are higher than the damping ratio of pure sand. This is because of the high compression performance of rubber particles.

[0094] Fig. 9 The dynamic shear modulus curves of three samples under a confining pressure of 100KPa show that under a confining pressure of 100KPa, the dynamic shear modulus of the rubber-sand mixture (Rc=10%) is smaller than that of pure sand. The fiber-rubber-sand mixture (Rc=10%, Fc=1%) has a certain shear resistance because the fiber plays a reinforcing role in the mixed soil particles, making its dynamic shear modulus greater than that of the rubber-sand mixture (Rc=10%).

[0095] Fig.10 The figure is a curve of the bearing ratio change of mixed soil for three samples at curing ages of 7d, 14d and 28d under 100KPa. The test results show that the bearing ratio of the mixed soil increases rapidly at the initial 7d to 14d of curing, and tends to be stable or increase slightly after 14d to 28d. The bearing ratio of the mixed soil (Rc = 10%) is much higher than that of pure sand, and the bearing ratio of the fiber rubber-sand mixed soil (Rc = 10%, Fc = 1%) is higher than that of the rubber-sand mixed soil.

[0096] In summary, from the perspective of mechanical properties, compared with pure sand and rubber-sand mixed soil, fiber rubber-sand mixed soil has a higher bearing capacity and better shock absorption effect; and, due to the effect of fibers, fiber rubber-sand mixed soil has higher shear strength and also improves the integrity of the soil.

[0097] The present invention adopts TPU material to hot-melt bond rubber particles and fiber material to form an integral material. The fiber rubber particles of the present invention can improve the bearing capacity and shear strength of the mixed soil and improve the integrity of the soil body.

[0098] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the profession, without departing from the scope of the technical solution of the present invention, according to the technical essence of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. A mold for preparing rubber fiber particles, characterized in that: It includes a base plate and an upper pressing plate that can cover and be fixed on the base plate; the upper inner surface of the base plate is provided with a plurality of first grooves, the lower inner surface of the upper pressing plate is provided with a plurality of second grooves corresponding to the first grooves, and the first grooves and the second grooves constitute a rubber fiber particle molding space; the upper pressing plate is connected to a heating device, and the heating device can heat the upper pressing plate; the upper pressing plate is provided with a plurality of material guiding heating holes, and each material guiding heating hole corresponds to and is connected with the position of each first groove.

2. The mold for preparing rubber fiber particles according to claim 1, characterized in that: The first groove and the second groove are both hemispherical.

3. The mold for preparing rubber fiber particles according to claim 1, characterized in that: The inner diameters of the first groove and the second groove are 4-6 mm.

4. A method for preparing rubber fiber particles capable of improving the mechanical properties of soil, characterized in that: The following steps are involved: Using the mold for preparing rubber fiber particles according to any one of claims 1 to 3, placing rock fiber into the first groove of the bottom plate; Place rubber powder in the groove where the rock fiber has been placed; Put the upper pressing plate on the bottom plate to fix the bottom plate and the upper pressing plate; Turn on the heating device and heat the upper platen to 150-200 degrees; Pour TPU powder into the material guide heating hole of the upper pressing plate. After 10-15 minutes, when the powder in the hole is heated into liquid and flows into the molding space formed by the first groove and the second groove, open the upper pressing plate. Allowing the mixture in the molding space to cool naturally to room temperature to obtain a composite fiber material; The composite fiber material in the mold is taken out and shredded to obtain rubber fiber particles that can improve the mechanical properties of the soil.

5. The method for preparing rubber fiber particles capable of improving the mechanical properties of soil according to claim 4, characterized in that: The bottom plate and the upper pressing plate of the mold for preparing rubber fiber particles are wiped clean on the inner surface before use, and lubricant is applied on the inner surface to facilitate later demoulding.

6. The method for preparing rubber fiber particles capable of improving the mechanical properties of soil according to claim 4, characterized in that: The rock fiber is at least one of basalt fiber, glass fiber and carbon fiber.

7. The method for preparing rubber fiber particles capable of improving the mechanical properties of soil according to claim 4, characterized in that: The size parameter of the rock fiber is 40±0.2 cm; the particle size of the rubber powder is 0.5-1 mm; the composite fiber material in the mold is taken out and the size parameter of the shredded material is 2.5-4.5 cm.

8. The method for preparing rubber fiber particles capable of improving the mechanical properties of soil according to claim 7, characterized in that: The mass ratio of rock fiber to rubber powder and TPU powder is 1-3:7-9:1; the total amount of rock fiber and rubber powder placed in each first groove of the bottom plate is 10±0.1g.

9. The rubber fiber particles prepared by the method according to any one of claims 4 to 8, characterized in that: The rubber fiber particles are composite fiber material particles of rock fiber, rubber and TPU.

10. A method for improving the mechanical properties of soil, characterized in that: The rubber fiber particles described in claim 9 are mixed with pure sand to form a fiber rubber-sand mixed soil, wherein the mixing amount of the rubber fiber particles is 5% to 20%.

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