Method for improving red clay with construction waste

Abstract

The application relates to the field of building materials, and particularly discloses a method for improving red clay with construction waste, which comprises the following steps: S1, loosening red clay; S2, uniformly mixing construction waste aggregate, a stabilizer and the loosened red clay to obtain improved soil; the addition amount of the construction waste aggregate is 10%-20% and the addition amount of the stabilizer is 4%-6% according to the weight of the red clay; the raw materials of the construction waste aggregate include brick-concrete construction waste and polar rubber powder, and the weight ratio of the brick-concrete construction waste to the polar rubber powder is 10: (1-2). The application has the effect of improving the water-erosion resistance of the improved soil and the stability of the foundation.

Description

Technical Field

[0001] This application relates to the field of building materials, and in particular to a method for improving red clay from construction waste. Background Technology

[0002] Red clay is widely distributed in southern my country, concentrated in Hunan, Guangxi, and Yunnan-Guizhou regions. It is characterized by large porosity, low density, and high water content; even a small amount of water loss can cause surface cracking. Changes in red clay such as consolidation, creep, collapse, and subsidence can easily lead to tilting and cracking of buildings located above red clay areas. Therefore, when using red clay as foundation fill, it needs to be improved. Currently, the main methods for improving red clay include physical improvement, chemical improvement, and a combination of physical and chemical methods. However, these methods consume large amounts of raw materials, resulting in resource depletion. There is an urgent need to find a cheaper and more environmentally friendly improvement method.

[0003] Using construction waste to improve red clay increases resource utilization, but construction waste contains water-soluble substances. Under the influence of water erosion, these water-soluble substances are lost with the water, leading to increased compression deformation, reduced compressive strength, and decreased stability of the red clay foundation. Summary of the Invention

[0004] In order to improve the water resistance of the improved soil and thus improve the stability of the foundation, this application provides a method for improving red clay with construction waste.

[0005] Firstly, the method for improving red clay from construction waste provided in this application adopts the following technical solution:

[0006] The method for improving red clay with construction waste includes the following steps:

[0007] S1, loose red clay;

[0008] S2. Mix the construction waste aggregate, stabilizer and loose red clay evenly to obtain improved soil;

[0009] Based on the weight of red clay, the amount of construction waste aggregate added is 10%-20%, and the amount of stabilizer added is 4%-6%;

[0010] The raw materials for preparing the construction waste aggregate include brick-concrete construction waste and polar rubber powder, and the weight ratio of the brick-concrete construction waste to the polar rubber powder is 10:(1-2).

[0011] By adopting the above technical solution, red clay, stabilizer and construction waste aggregate are mixed to improve the soil. The construction waste aggregate improves the bearing capacity of the improved soil. Polar rubber powder and polar substances such as cement particles and clay particles in brick-concrete construction waste as well as red clay particles mutually adsorb each other. The hydrophobicity and viscosity of polar rubber powder improve the hydrophobicity and self-compacting properties of brick-concrete construction waste. When water penetrates, the substances in the construction waste aggregate are not easily lost with the water, which improves the water erosion resistance of the improved soil and thus improves the stability of the foundation.

[0012] Optionally, the particle size of the brick-concrete construction waste is no greater than 16mm, and the moisture content of the brick-concrete construction waste is no greater than 5%.

[0013] By adopting the above technical solutions, the maximum particle size of brick-concrete construction waste is controlled. A large particle size of brick-concrete construction waste easily leads to stratification when mixed with red clay, and is inconvenient for backfilling. Using brick-concrete construction waste smaller than 16mm facilitates uniform mixing of the waste with red clay and allows for proper backfilling. Controlling the moisture content of the brick-concrete construction waste reduces the moisture content of the improved soil, improving its resistance to water erosion and thus enhancing the stability of the foundation.

[0014] Optionally, the raw materials for preparing the polar rubber powder include rubber powder and coupling agent, wherein the weight ratio of rubber powder to coupling agent is 20:(1-3).

[0015] By adopting the above technical solution, the surface of the rubber powder particles is non-polar, while the sand, gravel, cement particles, and clay particles in the brick-concrete construction waste are polar. There are obvious gaps between the rubber powder particles and the polar substances in the brick-concrete construction waste, preventing the rubber powder particles from forming an effective hydration reaction at the bonding surface. Since rubber powder is a hydrophobic polymer, the bonding strength between the brick-concrete construction waste and the rubber powder particles is low, resulting in reduced compressive strength and water erosion resistance of the construction waste aggregate, thus decreasing the stability of the foundation. The coupling agent modifies the rubber powder to form polar rubber powder, improving the bonding strength between the rubber powder particles and the brick-concrete construction waste bonding surface, thereby increasing the compressive strength and water erosion resistance of the improved soil, and ultimately improving the stability of the foundation.

[0016] Optionally, the coupling agent is triethanolamine borate.

[0017] By adopting the above technical solution, triethanolamine borate contains amino groups that are affinity for rubber powder particles. At the same time, the amino groups are also electron-rich groups that can form a nitrogen-boron internal coordination structure with electron-deficient boron atoms, filling the empty p orbitals, preventing the hydrolysis of the triethanolamine borate coupling agent, improving the water erosion resistance of the polar rubber powder modified construction waste fine aggregate, thereby improving the water erosion resistance of the improved soil and thus improving the stability of the foundation.

[0018] Optionally, the preparation of the polar rubber powder includes the following steps: dispersing the coupling agent in ethanol, adding rubber powder, soaking for 1-2 hours, heating to 100-120℃, stirring at a constant temperature for 15-25 minutes, cooling, rinsing with water, drying, shaking, grinding, and sieving to obtain polar rubber powder.

[0019] By adopting the above technical solution, the coupling agent is evenly dispersed and adsorbed on the rubber powder particles through ethanol dispersion. Under the action of temperature and mechanical force, the rubber powder particles and the coupling agent react fully, which increases the loading of polar molecules on the surface of the rubber powder particles. This facilitates the loading of polar rubber powder on the surface of brick and concrete construction waste particles, thereby improving the water resistance of construction waste aggregate.

[0020] Optionally, the amount of coupling agent added is: the concentration of coupling agent in ethanol is 50-150 g / L.

[0021] By adopting the above technical solution, the coupling agent is evenly dispersed and is easy to load onto the surface of rubber powder particles, thereby facilitating the subsequent reaction between the coupling agent and the rubber powder.

[0022] Optionally, the stabilizer includes activated fly ash and perfluorooctyltrichlorosilane, wherein the weight ratio of activated fly ash to perfluorooctyltrichlorosilane is 10:(0.1-1).

[0023] By employing the above technical solution, perfluorooctyltrichlorosilane is adsorbed onto activated fly ash, which then assists in the uniform dispersion of the activated fly ash in the improved soil. Upon hydration, the activated fly ash forms silicate compounds, and perfluorooctyltrichlorosilane enhances the water resistance of these compounds. Polar rubber powder is uniformly distributed on the surface of brick-concrete construction waste particles. With the addition of a stabilizer, the rubber powder, silicate compounds, and perfluorooctyltrichlorosilane form a three-dimensional waterproof structure, improving the water resistance of the construction waste aggregate and thus providing foundation stability.

[0024] Optionally, the following steps may also be included:

[0025] S3. Fill the improved soil onto the foundation construction surface, compact and level it;

[0026] S4. Grouting, curing the subgrade;

[0027] S5. Repeat S3-S5 to obtain the foundation.

[0028] By adopting the above technical solutions, grouting improves the stability and self-density of the improved soil, making it less likely for water to seep into the foundation; cement hydration consumes the water in the improved soil, reducing the moisture content of the foundation and improving its stability.

[0029] Optionally, the grout used for grouting is neat cement paste.

[0030] By adopting the above technical solution, cement paste penetrates into the pores of the improved soil, improving the compressive strength of the fill material; the cement paste reacts with the water in the red clay, reducing the moisture content of the improved soil, increasing the bonding strength and self-compacting properties of the improved soil, and making it difficult for water to penetrate into the improved soil, thereby improving the water resistance of the improved soil and thus improving the stability of the foundation.

[0031] In summary, this application includes at least one of the following beneficial technical effects:

[0032] 1. After crushing, brick-concrete construction waste is mixed with polar rubber powder. Under the action of polar groups, the polar rubber powder binds tightly to the brick-concrete construction waste particles and prevents water molecules from penetrating into the interior of the brick-concrete construction waste particles. This prevents the loss of water-soluble substances in the brick-concrete construction waste, improves the stability of the construction waste aggregate, thereby improving the water erosion resistance of the improved soil and thus improving the stability of the foundation.

[0033] 2. Triethanolamine borate contains amino groups that are affinity for rubber powder particles. At the same time, the amino groups are also electron-rich groups that can form a nitrogen-boron internal coordination structure with electron-deficient boron atoms, filling the empty p orbitals, preventing the hydrolysis of the triethanolamine borate coupling agent, improving the water erosion resistance of polar rubber powder modified construction waste fine aggregate, thereby improving the water erosion resistance of the improved soil and thus improving the stability of the foundation.

[0034] 3. Perfluorooctyltrichlorosilane is adsorbed onto activated fly ash, and perfluorooctyltrichlorosilane assists in the uniform dispersion of activated fly ash in the improved soil. After hydration, activated fly ash forms silicate compounds, and perfluorooctyltrichlorosilane improves the water resistance of silicate compounds. Polar rubber powder is uniformly distributed on the surface of brick-concrete construction waste particles. After the addition of stabilizers, the rubber powder, silicate compounds and perfluorooctyltrichlorosilane form a three-dimensional waterproof structure, which improves the water resistance of construction waste aggregate, thereby providing the stability of the foundation. Attached Figure Description

[0035] Figure 1 It is the corrosion resistance test device in performance test 4 of this application;

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. Waterproof tank; 11. Drain outlet; 2. Container; 21. Leakage hole; 3. Support frame; 4. Water pipe; 5. Faucet. Detailed Implementation

[0038] The following is in conjunction with the appendix Figure 1 The present application will be further described in detail with reference to the embodiments and comparative examples.

[0039] Unless otherwise specified, the following examples shall be conducted under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all raw materials used in the following examples shall be commercially available.

[0040] The red clay has a moisture content of 24.8% and a dry density of 1.227 g / cm³. 3 The plastic limit is 22.15%, and the liquid limit is 46.52%.

[0041] The brick-concrete construction waste is obtained by crushing construction waste rich in concrete, mortar, and bricks. The moisture content is 1.7%, and the sieving results are as follows: 20.8% passing through a 4.75mm sieve, 57.4% passing through a 9.5mm sieve, 90.4% passing through a 13.2mm sieve, and 100% passing through a 16mm sieve. The rubber powder is processed from waste tires, with a particle size of 80 mesh and a softening temperature of (150±2)℃. Triethanolamine borate is a water-based coupling agent with a melting point of 44℃. Activated fly ash is mechanically activated, with a density of 2.45 kg / m³. 3 The particle size is 325 mesh, and the compressive strength is 7 MPa. Perfluorooctyltrichlorosilane, also known as 1H,1H,2H,2H-perfluorooctyltrichlorosilane, is a colorless, transparent liquid. The cement is P042.5 type silicate cement with a specific surface area of ​​352 m². 2 / kg, initial setting time 204min, final setting time 254min, 28d compressive strength 50.4MPa, 28d flexural strength 7.4MPa. Example

[0042] Example 1

[0043] S1. Turn over the red clay and shake it to loosen it;

[0044] S2. Preparation of improved soil, including the following steps:

[0045] (1) Disperse 0.5 kg of triethanolamine borate in 10 L of ethanol, add 10 kg of rubber powder, soak for 1 h, heat to 120 °C, stir at constant temperature for 15 min at a stirring speed of 40 r / min, cool to room temperature and rinse with water, then dry at constant temperature of 40 °C for 40 min, shake, grind and sieve to obtain polar rubber powder with a particle size of 80 mesh;

[0046] (2) Take 50kg of brick-concrete construction waste and mix it with 5kg of polar rubber powder prepared in step (1). Heat the mixture to 140℃ and stir for 30 minutes at a constant temperature. Stir at a speed of 120r / min to obtain construction waste aggregate.

[0047] (3) Mix 10 kg of activated fly ash and 0.1 kg of perfluorooctyltrichlorosilane evenly as a stabilizer;

[0048] (4) Take 100kg of red clay, 10kg of construction waste aggregate prepared in step (2) and 4kg of stabilizer prepared in step (3), mix them evenly, pile them in one place, cover them with a film for 3 days, the temperature is (20±2)℃ and the humidity is (65±2)%, and the improved soil is obtained.

[0049] Example 2

[0050] S1. Turn over the red clay and shake it to loosen it;

[0051] S2. Preparation of improved soil, including the following steps:

[0052] (1) Disperse 1 kg of triethanolamine borate in 10 L of ethanol, add 10 kg of rubber powder, soak for 1.5 h, heat to 110 °C, stir at constant temperature for 20 min at a stirring speed of 40 r / min, cool to room temperature and rinse with water, then dry at constant temperature of 40 °C for 30 min, shake, grind and sieve to obtain polar rubber powder with a particle size of 80 mesh;

[0053] (2) Take 50kg of brick-concrete construction waste and mix it with 8kg of polar rubber powder prepared in step (1). Heat the mixture to 140℃ and stir for 30 minutes at a constant temperature. Stir at a speed of 120r / min to obtain construction waste aggregate.

[0054] (3) Mix 10 kg of activated fly ash and 0.5 kg of perfluorooctyltrichlorosilane evenly as a stabilizer;

[0055] (4) Take 100kg of red clay, 15kg of construction waste aggregate prepared in step (2) and 5kg of stabilizer prepared in step (3), mix them evenly, pile them in one place, cover them with a film for 3 days, the temperature is (20±2)℃ and the humidity is (65±2)%, and the improved soil is obtained.

[0056] Example 3

[0057] S1. Turn over the red clay and shake it to loosen it;

[0058] S2. Preparation of improved soil, including the following steps:

[0059] (1) Disperse 1.5 kg of triethanolamine borate in 10 L of ethanol, add 10 kg of rubber powder, soak for 2 h, heat to 100 °C, stir at constant temperature for 25 min at a stirring speed of 40 r / min, cool to room temperature and rinse with water, then dry at constant temperature of 40 °C for 20 min, shake, grind and sieve to obtain polar rubber powder with a particle size of 80 mesh;

[0060] (2) Take 50kg of brick-concrete construction waste and mix it with 10kg of polar rubber powder prepared in step (1). Heat the mixture to 140℃ and stir for 30 minutes at a constant temperature. Stir at a speed of 120r / min to obtain construction waste aggregate.

[0061] (3) Mix 10 kg of activated fly ash and 1 kg of perfluorooctyltrichlorosilane evenly as a stabilizer;

[0062] (4) Take 100kg of red clay, 20kg of construction waste aggregate prepared in step (2) and 6kg of stabilizer prepared in step (3), mix them evenly, pile them in one place, cover them with a film for 3 days, the temperature is (20±2)℃ and the humidity is (65±2)%, and the improved soil is obtained.

[0063] Example 4

[0064] The difference from Example 2 is that the amount of stabilizer added in step (4) is 4 kg.

[0065] Example 5

[0066] The difference from Example 2 is that the amount of stabilizer added in step (4) is 6 kg.

[0067] Example 6

[0068] The difference from Example 2 is that the amount of construction waste aggregate added in step (4) is 10kg.

[0069] Example 7

[0070] The difference from Example 2 is that the amount of construction waste aggregate added in step (4) is 20kg.

[0071] Example 8

[0072] The difference from Example 2 is that the amount of polar rubber powder added in step (2) is 5 kg.

[0073] Example 9

[0074] The difference from Example 2 is that the amount of polar rubber powder added in step (2) is 10 kg.

[0075] Example 10

[0076] The difference from Example 2 is that the amount of triethanolamine borate added in step (1) is 0.5 kg.

[0077] Example 11

[0078] The difference from Example 2 is that the amount of triethanolamine borate added in step (1) is 1.5 kg.

[0079] Example 12

[0080] S1. Turn over the red clay and shake it to loosen it;

[0081] S2. Preparation of improved soil, including the following steps:

[0082] (1) Disperse 1 kg of triethanolamine borate in 10 L of ethanol, add 10 kg of rubber powder, soak for 1.5 h, heat to 110 °C, stir at constant temperature for 20 min at a stirring speed of 40 r / min, cool to room temperature and rinse with water, then dry at constant temperature of 40 °C for 30 min, shake, grind and sieve to obtain polar rubber powder with a particle size of 80 mesh;

[0083] (2) Take 50kg of brick-concrete construction waste and mix it with 8kg of polar rubber powder prepared in step (1). Heat the mixture to 140℃ and stir for 30 minutes at a constant temperature. Stir at a speed of 120r / min to obtain construction waste aggregate.

[0084] (3) Mix 10 kg of activated fly ash and 0.5 kg of perfluorooctyltrichlorosilane evenly as a stabilizer;

[0085] (4) Take 100kg of red clay, 15kg of construction waste aggregate prepared in step (2) and 5kg of stabilizer prepared in step (3), mix them evenly, pile them in one place, cover them with film and cure for 3 days, with a temperature of (20±2)℃ and a humidity of (65±2)%, and the improved soil is obtained.

[0086] S3. Fill the improved soil onto the foundation construction surface with a thickness of 20cm, then compact and level it.

[0087] S4. Grouting with neat cement paste, the water-cement ratio of the neat cement paste is 0.38, and the pouring amount of neat cement paste is 10 kg / m³. 2 Maintenance is carried out at the grassroots level;

[0088] S5. Repeat S3-S5 to obtain the foundation.

[0089] Comparative Example

[0090] Comparative Example 1

[0091] The difference from Example 2 is that no construction waste aggregate was added.

[0092] Comparative Example 2

[0093] The difference from Example 2 is that no polar rubber powder was added to the construction waste aggregate.

[0094] Comparative Example 3

[0095] The difference from Example 2 is that the polar rubber powder was replaced with rubber powder, and the rubber powder was not modified.

[0096] Comparative Example 4

[0097] The difference from Example 2 is that no stabilizer was added.

[0098] Comparative Example 5

[0099] The difference from Example 2 is that perfluorooctyltrichlorosilane was not added, and activated fly ash was used as a stabilizer.

[0100] Table 1. Raw material list for the examples and comparative examples

[0101]

[0102] Performance testing

[0103] 1. Following the methods in GB / T 50123-2019 Standard for Geotechnical Testing Methods, the shear strength (kPa) of the modified soil was determined using the LF-TAS fully automatic triaxial shear apparatus. The test procedures are as follows:

[0104] (1) Sample preparation: The sample is a cylinder with a diameter of 101 mm and a height of 80 mm. Weigh one-fifth of the calculated mass each time and pour it into the compactor to compact in layers. After each layer is compacted, the surface should be roughened before compacting the next layer. After compaction, the sample is placed into the saturator. Three samples are prepared for each set of improved soil prepared in the examples / comparative examples.

[0105] (2) Use the vacuum pumping saturation method to saturate the sample. Place the permeable plate, filter paper, sample, filter paper, and permeable plate in the saturator in sequence. Finally, straighten the pull rod on the top of the saturator and tighten the upper nut to fix the sample. Then place the saturator in the vacuum cylinder and apply a layer of Vaseline between the vacuum cylinder and the cylinder cover to ensure the airtightness of the vacuum cylinder and the cylinder cover. Connect the vacuum cylinder to the pump and start the pump. When the vacuum pressure gauge reading is close to the local atmospheric pressure, slightly open the water pumping pipe to pump water. When the water in the vacuum cylinder is slightly higher than the saturator, close the water pumping pipe. Place the sample in the vacuum cylinder for 10 hours to allow it to absorb water and become saturated.

[0106] (3) Referring to the “19.5 Consolidated Undrained Shear Test”, the latex film was placed inside the membrane support tube, with both the upper and lower ends covered by the membrane support tube. Then, the suction balloon was inserted into the membrane support tube to suck out the gas inside the tube. After sucking out the gas, the sample was put into the membrane support tube and taken out together with the latex film. In the pressure chamber, the permeable stone, the sample, and the permeable stone were placed in sequence on the base. Then, the two ends of the latex film were fixed with rubber bands.

[0107] (4) Open the pumping valve to fill the pressure chamber with water;

[0108] (5) The LF-TAS fully automatic triaxial shear apparatus was set with a confining pressure of 200 kPa and a shear rate of 0.08 mm / min to perform saturation, consolidation and shearing operations to obtain the shear strength (kPa). The test results are detailed in Table 2.

[0109] 2. The 28-day unconfined compressive strength (MPa) of the modified soil was tested using the method of "20 Unconfined Compressive Strength Test" in GB / T 50123-2019 Standard for Geotechnical Testing Methods. The sample height was 4 cm and the sample height was 8 cm. The test results are detailed in Table 2.

[0110] 3. Following the method described in "17 Consolidation Test" of GB / T 50123-2019 Standard for Geotechnical Testing Methods, the improved soil was dried in an oven. After drying, the sample was weighed and mixed with water at the optimum moisture content and maximum dry density, and then allowed to stand. The soil was tested under a preload of 1 kPa, followed by further pressurization to 300 kPa, to measure the void ratio and compressibility coefficient (MPa) of the improved soil. -1 The test results are detailed in Table 2, which shows the compressive modulus (MPa) and the compressive modulus (MPa).

[0111] 4. Referring to the method of "42 Test Pit Permeability Test" in GB / T 50123-2019 Standard for Geotechnical Testing Methods, the water resistance of the improved soil was tested, and the steps are as follows:

[0112] (1) Sample preparation: The sample is a cylinder with a diameter of 101 mm and a height of 100 mm; one-fifth of the calculated mass is weighed each time and poured into the sampler in layers and compacted. Cement grout is then poured. The water-cement ratio of the cement grout is 0.38, and the amount of cement grout poured is 5 kg / m³. 2 After curing for 3 days, the next layer of improved soil is filled in; 3 samples are prepared for each set of improved soils prepared in the examples / comparative examples.

[0113] (2) Control group 1 used the improved soil prepared in Example 2 as raw material. The prepared sample was a cylinder with a diameter of 101 mm and a height of 100 mm. One-fifth of the calculated mass was weighed and poured into the sampler and compacted in layers. After each layer was compacted, the surface was roughened before the next layer was compacted. Three samples were prepared in the same way. Control group 2 used the improved soil prepared in Comparative Example 1 as raw material. The prepared sample was a cylinder with a diameter of 101 mm and a height of 100 mm. One-fifth of the calculated mass was weighed and poured into the sampler and compacted in layers. After each layer was compacted, the surface was roughened before the next layer was compacted. Three samples were prepared in the same way.

[0114] (3) Test the moisture content of the sample and weigh the sample, and record the initial weight m1;

[0115] (4) Reference Figure 1The anti-corrosion test device includes a waterproof box 1, a container 2, a support 3, a water pipe 4, and a faucet 5 installed on the water pipe. The waterproof box 1 is a waterproof box with an open top wall, and a drain outlet 11 is provided on the periphery of the waterproof box 1. A water leakage hole 21 is provided on the bottom wall of the container 2. The container 2 is placed in the waterproof box 1 through the support 3, and the height of the upper surface of the container 2 is lower than the vertical height of the drain outlet 11. The faucet 5 is located above the waterproof box 1, and the water outlet of the faucet 5 faces the container 2. The end of the water pipe 4 away from the faucet 5 is connected to a water source. Water is filled into the waterproof box 1, and the sample is placed in the container 2. The container 2 containing the sample is placed on the support 3 in the waterproof box 1. At this time, the water in the waterproof box 1 overflows the sample. The faucet 5 is turned on, the water flow rate is 0.04m / s, and the timing is started. After 24 hours, the sample is taken out, dried to the moisture content measured in step (2), weighed, and the weight m2 is recorded.

[0116] (4) Record the weight change rate (%) = (m1-m2) / m1, which reflects the resistance of the improved soil to erosion. The test results are detailed in Table 2.

[0117] Table 2. Test results data for each embodiment and comparative example.

[0118]

[0119] Combining Examples 1, 2, and 3, by adjusting the method of improving red clay with construction waste, the ratio of red clay, construction waste aggregate and stabilizer, as well as the type of construction waste aggregate and stabilizer, improved soil samples with high strength, low porosity, low compressibility coefficient and high compression modulus, and water-resistant subgrade samples were prepared.

[0120] Combining Examples 2, 4, and 5, the differences among them are: the amount of stabilizer added is different. In Example 2, when preparing the improved soil, the amount of stabilizer added was 5 kg, which is 5% based on the weight of red clay; in Example 4, the amount of stabilizer added was 4 kg, which is 4% based on the weight of red clay; and in Example 5, the amount of stabilizer added was 6 kg, which is 6% based on the weight of red clay. As can be seen from Table 2, the improved soil prepared in Example 2 has the highest shear strength, 28-day unconfined compressive strength, and compression modulus, and the smallest weight change rate. The improved soil prepared in Example 5 has the lowest void ratio and compression coefficient. That is, as the amount of stabilizer added increases, the shear strength, 28-day unconfined compressive strength, and compression modulus of the improved soil first increase and then decrease, while the void ratio and compression coefficient of the improved soil decrease, and the weight change of the improved soil first decreases and then increases.

[0121] The differences between Examples 2, 6, and 7 lie in the amount of construction waste aggregate added. In Example 2, 15 kg of construction waste aggregate was added to prepare the improved soil, which is 15% of the weight of red clay. In Example 6, 10 kg of construction waste aggregate was added, which is 10% of the weight of red clay. In Example 7, 20 kg of construction waste aggregate was added, which is 10% of the weight of red clay. The amount of construction waste aggregate added was 20%. As can be seen from Table 2, the improved soil prepared in Example 7 had the highest shear strength and 28-day unconfined compressive strength, while the improved soil prepared in Example 2 had the lowest void ratio and compression coefficient, the highest compression modulus, and the lowest weight change rate. That is, as the amount of construction waste aggregate added increases, the shear strength and 28-day unconfined compressive strength of the improved soil increase, the void ratio and compression coefficient of the improved soil first decrease and then increase, the compression modulus of the improved soil first increases and then decreases, and the weight change of the improved soil first decreases and then increases.

[0122] Construction waste aggregate is made from brick-concrete construction waste and polar rubber powder. The brick-concrete construction waste provides the strength, while the polar rubber powder, in combination with the brick-concrete construction waste, improves the bond strength between the construction waste aggregate and red clay, and also improves the water erosion resistance of the improved soil. As the amount of construction waste aggregate added increases, the strength of the improved soil increases, but the porosity also increases, and the deformation difficulty of the improved soil initially increases and then decreases.

[0123] Combining Examples 2, 8, and 9, the differences among them lie in the amount of polar rubber powder added during the preparation of construction waste aggregate. In Example 2, the amount of polar rubber powder added is 8 kg, and the weight ratio of brick-concrete construction waste to polar rubber powder is 25:4; in Example 8, the amount of polar rubber powder added is 5 kg, and the weight ratio of brick-concrete construction waste to polar rubber powder is 10:1; in Example 9, the amount of polar rubber powder added is 10 kg, and the weight ratio of brick-concrete construction waste to polar rubber powder is 5:1. As shown in Table 2, the improved soil prepared in Example 8 has the highest shear strength and 28-day unconfined compressive strength; the improved soil prepared in Example 9 has the lowest void ratio and compression coefficient, the highest compression modulus, and the lowest weight change rate. That is, with the increase of the amount of polar rubber powder added, the improved soil's shear strength and 28-day unconfined compressive strength decrease, its void ratio and compression coefficient decrease, its compression modulus increases, and its weight change rate decreases.

[0124] The raw materials for preparing polar rubber powder include rubber powder and triethanolamine borate. Triethanolamine borate provides polar groups for the rubber powder, which improves the bonding strength between the polar rubber powder and brick-concrete construction waste, reduces the porosity of the construction waste aggregate, and improves the deformation resistance of the construction waste aggregate. However, as the proportion of polar rubber powder increases, the proportion of brick-concrete construction waste decreases, and the compressive strength of the construction waste aggregate decreases.

[0125] The differences between Examples 2, 10, and 11 are as follows: the amount of triethanolamine borate added during the preparation of polar rubber powder is different. In Example 2, the amount of triethanolamine borate added is 1 kg, and the weight ratio of rubber powder to triethanolamine borate is 10:1; in Example 10, the amount of triethanolamine borate added is 0.5 kg, and the weight ratio of rubber powder to triethanolamine borate is 20:1; in Example 11, the amount of triethanolamine borate added is 1.5 kg, and the weight ratio of rubber powder to triethanolamine borate is 20:3. As can be seen from Table 2, the improved soil prepared in Example 2 has the highest shear strength and 28-day unconfined compressive strength, the lowest void ratio and compression coefficient, the highest compression modulus, and the lowest weight change rate. That is, as the amount of polar rubber powder added increases, the shear strength, 28-day unconfined compressive strength, and compression modulus of the improved soil first increase and then decrease; the void ratio and compression coefficient of the improved soil first decrease and then increase; and the weight change of the improved soil first decreases and then increases. With the increase of triethanolamine borate, some triethanolamine borate does not react with rubber powder and acts as a lubricant in the improved soil, which reduces the soil's resistance to deformation, reduces its strength, and increases its rate of weight change.

[0126] Compared to Example 2, no construction waste aggregate was added when preparing the improved soil in Comparative Example 1. As can be seen from Table 2, the shear strength and 28-day unconfined compressive strength of the improved soil prepared in Comparative Example 1 were significantly reduced, while the void ratio and compression coefficient of the improved soil were significantly increased, the compression modulus of the improved soil was significantly reduced, and the weight change rate of the improved soil was significantly increased.

[0127] Compared to Comparative Example 1, Comparative Example 2 added brick-concrete construction waste. As can be seen from Table 2, the addition of brick-concrete construction waste improved the shear strength, 28-day unconfined compressive strength, and compression modulus of the improved soil, and reduced the weight change rate of the improved soil, but increased the void ratio and compression coefficient of the improved soil.

[0128] Compared to Comparative Example 2, Comparative Example 3 added rubber powder. The rubber powder was mixed with brick-concrete construction waste to prepare construction waste aggregate. As shown in Table 2, the addition of rubber powder improved the shear strength and 28-day unconfined compressive strength of the improved soil, reduced the void ratio and compression coefficient, increased the compression modulus, and decreased the weight change rate of the improved soil. Compared to Example 2, the absence of triethanolamine borate significantly affected the weight change rate of the improved soil and reduced its resistance to water erosion.

[0129] Compared to Example 2, no stabilizer was added when preparing the improved soil in Comparative Example 4. As can be seen from Table 2, the addition of the improver effectively improved the shear strength and 28-day unconfined compressive strength of the improved soil, reduced the void ratio and compression coefficient of the improved soil, increased the compression modulus of the improved soil, and reduced the weight change rate of the improved soil.

[0130] Compared to Comparative Example 4, Comparative Example 5 used activated fly ash as a modifier and did not add perfluorooctyltrichlorosilane. Combining Example 2, Comparative Example 4 and Comparative Example 5 with Table 2, it can be seen that activated fly ash improved the shear strength and 28-day unconfined compressive strength of the modified soil, reduced the void ratio and compression coefficient of the modified soil, increased the compression modulus of the modified soil, and increased the weight change rate of the modified soil.

[0131] Compared to Example 2, Control Group 1 did not pour cement paste. As can be seen from Table 2, the use of cement paste reduced the weight change rate of the improved soil.

[0132] Compared to control group 1, the improved soil used in control group 2 did not contain construction waste aggregates and stabilizers. Although cement slurry was poured, the samples were loose and unformed after the water resistance test, and the weight change rate could not be obtained.

[0133] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for improving red clay with construction waste, characterized in that, Includes the following steps: S1, loose red clay; S2. Mix the construction waste aggregate, stabilizer and loose red clay evenly to obtain improved soil; Based on the weight of red clay, the amount of construction waste aggregate added is 10%-20%, and the amount of stabilizer added is 4%-6%; The raw materials for preparing the construction waste aggregate include brick-concrete construction waste and polar rubber powder, with a weight ratio of 10:(1-2) for the brick-concrete construction waste and polar rubber powder. The raw materials for preparing the polar rubber powder include rubber powder and coupling agent, with a weight ratio of 20:(1-3) for the rubber powder and coupling agent. The coupling agent is triethanolamine borate.

2. The method for improving red clay from construction waste according to claim 1, characterized in that, The particle size of the brick-concrete construction waste is no greater than 16mm, and the moisture content of the brick-concrete construction waste is no greater than 5%.

3. The method for improving red clay from construction waste according to claim 1, characterized in that, The preparation of the polar rubber powder includes the following steps: dispersing the coupling agent in ethanol, adding rubber powder, soaking for 1-2 hours, heating to 100-120℃, stirring at a constant temperature for 15-25 minutes, cooling, rinsing with water, drying, shaking, grinding, and sieving to obtain polar rubber powder.

4. The method for improving red clay from construction waste according to claim 3, characterized in that, The concentration of the coupling agent in ethanol is 50-150 g / L.

5. The method for improving red clay from construction waste according to claim 1, characterized in that, The stabilizer comprises activated fly ash and perfluorooctyltrichlorosilane, wherein the weight ratio of activated fly ash to perfluorooctyltrichlorosilane is 10:(0.1-1).

6. The application of the method for improving red clay with construction waste according to claim 1 in foundation preparation, characterized in that, Includes the following steps: S3. Fill the foundation construction surface with improved red clay, compact and level it; S4. Grouting, curing the subgrade; S5. Repeat S3-S4 to obtain the foundation.

7. The application of the construction waste-modified red clay according to claim 6 in foundation preparation, characterized in that, The grout used for grouting is cement paste.

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