Alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material and preparation method thereof

Abstract

The invention discloses an alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material and a preparation method thereof. The alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material mainly comprises a soil material and an alkali activator, wherein the soil body material comprises in-situ soil, slag, fly ash and bentonite; the alkali activator comprises sodium silicate and sodium hydroxide. The alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material can be obtained by mixing the soil materials according to a certain proportion, then adding the alkali activator, continuing to stir and mix, and maintaining the soil materials to obtain the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material. Through impermeability and compressive property tests and barrier property experiments, the permeability coefficient and compressive strength of the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material prepared by the preparation method disclosed by the invention can meet related requirements of Technical Specification for Vertical Barrier of Industrial Polluted Site (HG / T 20715-2020); and a very good barrier effect can be achieved on inorganic heavy metals, organic pollutants and inorganic-organic composite pollutants.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of industrial contaminated site vertical barrier wall, and particularly relates to a kind of alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of China's economy and urbanization, the development of mineral resources, the construction of waste landfill sites and the illegal discharge of wastewater from chemical sites have caused serious pollution of soil and groundwater. Typical pollutants include Cr, Cd, Pb, vinyl chloride, 1,2-dichloroethylene, etc. These pollutants will migrate and diffuse to the aquifer with rainfall, thereby polluting people's domestic water, and ultimately posing a serious threat to human health and the ecological environment. In order to protect the quality of groundwater, a barrier technology is needed to retain pollutants in place, limit their migration, and thus reduce the impact of pollutants on the groundwater environment. Vertical barrier wall technology is a barrier material composed of impermeable pollution interception materials and in-situ soil, which is constructed into an underground wall structure in a vertical arrangement to ensure that the design service life meets the risk control target of the contaminated site. Common vertical barrier walls include bentonite systems (in-situ soil-bentonite), cement systems (cement soil and in-situ soil-cement-bentonite), etc.

[0003] For example, application No. 202211153074.X discloses a preparation method and application of a loess-modified bentonite vertical barrier wall material. The modified bentonite is first hydrated for more than 12 hours with loess as the base material. The dried loess is sieved, and the fine particle component is taken. Then, the fine loess, hydrated modified bentonite and water are mixed in proportion and stirred in a vacuum mixer for more than 4 hours. The mixture is injected into a soil sample cylinder in batches and oscillated synchronously. Then, the soil sample is left to stand for 24 hours, and after draining by gravity, it is consolidated until the permeability coefficient is reduced to 10- 7 cm / s. The loess-modified bentonite vertical barrier wall material can adsorb and block organic or inorganic pollutants, and is suitable for remediation and treatment of contaminated sites with different leachate compositions; however, the vertical barrier wall material of the invention has low compressive strength and cannot be applied to chemical contaminated sites under complex geological conditions, and the permeability coefficient does not meet the requirement of <1.0 x 10 -7 cm / s in the "Industrial Contaminated Site Vertical Barrier Technology Standard" (HG / T 20715-2020), and the present invention innovatively solves the above problems.

[0004] Application No. 202411256078.X discloses a kind of biochar base alkali excitation control material and its preparation method and application, the invention biochar base alkali excitation control material is made of in-situ soil with mass percentage 50~70% and 30~50% of colloidal material.It includes grey material and composite alkali excitation agent, which is prepared by co-milling of active magnesium oxide and biochar.The invention's biochar base alkali excitation control material has excellent early compressive strength under low cement mortar ratio conditions;At the same time, the introduction of biochar makes the adsorption and retention effect of the material on soil pollutants better, and the permeability coefficient can reach 2.4×10- 8 cm / s;But the biochar required by the invention needs to be pyrolyzed at 500~700℃ for 1~3 hours, then dried with active magnesium oxide for 4~6 hours, and finally ground in a ball mill for 2~3 hours, which is a complicated and time-consuming process, not suitable for use in chemical pollution sites that need to be quickly completed, and the invention innovatively solves the above problems.

[0005] Application No. 202211082891.0 discloses a modified cement-based vertical barrier material and its preparation method, which includes modified agent 0.25~3.75%, cement 4.75~11.25%, bentonite 5~15%, and in-situ soil 70~90% by mass percentage.The modified cement-based vertical barrier material has excellent resistance to sulfate attack, and is suitable for anti-seepage and anti-pollution barrier engineering construction in sulfate-rich leachate scenarios;But the invention needs to activate rice husk ash in the early stage, which needs to use multiple organic chemical reagents, and there is a risk of secondary pollution, the process is complicated and time-consuming, and the cement used belongs to high CO2 emission, which does not comply with the current development policy of our country, and the invention innovatively solves the above problems.

[0006] Geng Kaiqiang of Xi'an University of Technology in his doctoral thesis "Mechanical properties and engineering characteristics of alkali-activated slag-soil-bentonite vertical barrier" mentioned that sodium silicate and sodium hydroxide were used as alkali activator to activate slag, and soil and bentonite were added to make vertical barrier material, which was mixed with ZnCl2 solution for dynamic barrier, and it was found that the equilibrium barrier rate of heavy metal Zn 2+ of the barrier material showed a growth trend with the dosage of slag, alkali activator and bentonite, and the time required to reach the barrier equilibrium state of Zn 2+ was 72 hours.Although the material has good barrier effect on heavy metal Zn 2+ , the paper only focuses on single heavy metal pollution, and does not explore the barrier effect of the material on organic pollutants and inorganic-organic composite pollutants, and the invention innovatively explores the above problems.

[0007] The in-situ soil-bentonite vertical barrier wall has low strength and is suitable for large-scale pollution sites without strength requirements; the cement-based vertical barrier wall has high strength and is widely used; however, the cement has poor impermeability, the hydration process and product structure are easily affected by pollutants, and the service life is greatly reduced; at the same time, the traditional cement-based vertical barrier wall has limited barrier capacity for chemical industry site pollutants, and is usually not suitable for inorganic heavy metal and organic compound pollution sites; in addition, the production of cement is a high energy consumption process and does not meet the current development policy of China. Alkali-activated gel material refers to the dissolution-depolymerization-polycondensation reaction of silicate powder under the action of alkali activator to form a gel structure. Compared with cement, the alkali-activated gel material has lower CO2 emission and energy consumption, and has stronger impermeability, compressive strength, high temperature resistance and sulfate corrosion resistance under the same conditions. Slag is a byproduct produced in the blast furnace ironmaking process, and fly ash is a byproduct after coal combustion, both of which are mainly composed of CaO, SiO2, Al2O3 and other oxides; the vertical barrier wall prepared by using alkali activator to activate slag and fly ash to form a gel material has the advantages of high strength and good impermeability. As an additive of the vertical barrier wall material, the addition of bentonite can effectively reduce the permeability coefficient of the vertical barrier wall and enhance the barrier capacity of the vertical barrier wall to pollutants in groundwater. Therefore, in view of the problems existing in the prior art, the alkali-activated slag and fly ash gel material is used to replace cement, the problem that the hydration process and product structure of the vertical barrier wall material are easily affected by pollutants is solved, bentonite and in-situ soil are added, the impermeability, compressive strength and barrier performance to complex pollutants are effectively enhanced, and the vertical barrier wall material is suitable for inorganic heavy metal and organic compound chemical pollution sites; in addition, the vertical barrier wall material has the advantages of green environmental protection and low CO2 emission. SUMMARY

[0008] The present application aims to overcome the deficiencies in the prior art of vertical barrier wall materials and provide an alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material and a preparation method thereof. The material prepared by the present application can effectively block inorganic-organic compound pollution sites.

[0009] In order to achieve the above-mentioned purpose, the present application has the following technical solutions:

[0010] A soil vertical barrier wall material is composed of a soil material and an alkali activator, the mass percentage of the soil material is 90-95%, and the mass percentage of the alkali activator is 5-10%.

[0011] As a preferred, in the soil vertical barrier wall material described above, the soil material is composed of in-situ soil, slag, fly ash and bentonite, and the mass percentage is: in-situ soil 65-73%, slag 15-25%, fly ash 3-8%, and bentonite 2-10%.

[0012] As preferred, in the soil vertical barrier wall material, the activity index of the slag is not less than S95, the fly ash is of grade II or above, and the bentonite is sodium-based bentonite.

[0013] As preferred, in the soil vertical barrier wall material, the alkali activator is sodium silicate and sodium hydroxide.

[0014] As preferred, in the soil vertical barrier wall material, the mass ratio of the alkali activator is 7.2%, in which the mass ratio of sodium silicate is 5% and the mass ratio of sodium hydroxide is 2.2%.

[0015] The preparation method of the soil vertical barrier wall material comprises the following steps:

[0016] Step 1, the in-situ soil is dried in an oven after removing impurities, then is crushed and sieved to obtain fine in-situ soil;

[0017] Step 2, sodium silicate and sodium hydroxide are mixed by stirring, then are added into a container containing water, sealed and then put into a stirring heater for continuous stirring to obtain an alkali activator;

[0018] Step 3, fine in-situ soil, slag, fly ash and bentonite are put into a stirrer for mixing according to a proportion, then the alkali activator is added and continuous stirring is performed to obtain an alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material.

[0019] As preferred, in the preparation method, the drying temperature in step 1 is 60℃ and the drying time is more than 24 hours; the mesh size of the sieve is 2mm.

[0020] As preferred, in the preparation method, the water in step 2 is pure water, the stirring temperature is 60℃, the stirring time is 10 minutes and the stirring speed is 500r / min.

[0021] As preferred, in the preparation method, the fine in-situ soil, slag, fly ash and sodium-based bentonite in step 3 are mixed by low-speed stirring, the rotating speed is 140r / min and the time is 2 minutes.

[0022] As preferred, in the preparation method, after the alkali activator is added in step 3, low-speed stirring is performed first, the rotating speed is 140r / min and the time is 2 minutes; then high-speed stirring is performed, the rotating speed is 285r / min and the time is 2 minutes.

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

[0024] The alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material has low cost and is green and environmentally friendly. On the one hand, compared with cement, slag and fly ash are industrial by-products, and the cost is 180-220 yuan / ton lower, and the preparation process does not use cement, which helps to save energy and reduce emissions. On the other hand, the in-situ soil is directly used as a raw material, which can avoid the secondary pollution and land occupation caused by the in-situ soil being stored in a place other than the original place, and can also reduce the engineering cost to a certain extent.

[0025] The alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material has excellent impermeability and compressive strength. The bentonite has good swelling property, so that the prepared alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material has a lower permeability coefficient, which meets the requirement of <1.0×10 -7 cm / s in the Industrial Contaminated Site Vertical Barrier Technical Specification (HG / T 20715-2020); the low permeability coefficient can enhance the barrier migration effect of the material on the pollutants, and prolong the service life of the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall. The compressive strength meets the requirement of not less than 0.1 MPa in the Industrial Contaminated Site Vertical Barrier Technical Specification (HG / T 20715-2020); the high compressive strength can ensure the normal use of the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall under complex geological conditions, which not only can expand the application range, but also can avoid the problems of wall cracking and increased diffusion range of pollutants caused by low strength of the vertical barrier wall.

[0026] The alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material has excellent barrier performance. The bentonite can exchange cations with heavy metal ions in the contaminated site, thereby having the characteristic of blocking the migration of pollutants; tests show that the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material has excellent barrier performance for typical pollutants in groundwater such as Cr, Cd, Pb, vinyl chloride and 1,2-dichloroethylene. Therefore, the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material can be applied to complex contaminated sites such as composite inorganic heavy metal pollution and inorganic-organic composite pollution, and can well block the migration and diffusion of pollutants. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Preparation flow chart of the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material;

[0028] Figure 2 Permeability coefficient curve graph of the examples and comparative examples;

[0029] Figure 3 Compressive strength column chart of the examples and comparative examples;

[0030] Figure 4Barrier rate column chart of the examples and comparative examples. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described in a complete and clear manner in combination with the drawings in the embodiments of the present application. Obviously, the embodiments in the present application are not all the embodiments, but only some of the embodiments. Based on the embodiments described in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application.

[0032] The activity index of the slag used in the embodiments should not be lower than S95 grade; the fly ash used is grade II or above; the bentonite used is sodium-based bentonite; the sodium silicate used is a solid particle; the sodium hydroxide is a particle, and the purity is greater than 95%; the above experimental materials can be purchased through a conventional route.

[0033] Embodiment 1

[0034] The alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material of the present application comprises a soil material and an alkali activator. The soil material comprises 73% of in-situ soil, 20% of slag, 5% of fly ash and 2% of sodium-based bentonite by mass ratio. The alkali activator dosage calculation formula is (mass of sodium silicate + mass of sodium hydroxide) / mass of soil material; the mass ratio of the alkali activator is 7.2%; wherein, the mass ratio of sodium silicate is 5%; the mass ratio of sodium hydroxide is 2.2%. The water mass ratio calculation formula is water mass / soil material mass, so the water mass ratio is 30%;

[0035] The preparation process is as shown in Figure 1 Step 1, after removing impurities, the in-situ soil is placed in a 60℃ oven for drying for more than 24 hours, then it is crushed and sieved with a 2mm sieve to obtain fine in-situ soil;

[0036] Step 2, after stirring and mixing 5% sodium silicate and 2.2% sodium hydroxide by mass ratio, they are added to a container containing 15% water by mass ratio, which is sealed and then placed in a stirring heater, the stirring temperature is 60℃, the stirring time is 10 minutes, and the stirring speed is 500r / min, and the alkali activator is obtained after stirring;

[0037] Step 3, put the fine-grained in-situ soil with a mass ratio of 73%, 20% of slag, 5% of fly ash and 2% of sodium bentonite into a blender for low-speed stirring and mixing, the rotating speed is 140 r / min, and the time is 2 minutes; then add the alkali activator and the remaining water with a mass ratio of 15%, first stir at a low speed, the rotating speed is 140 r / min, and the time is 2 minutes; then stir at a high speed, the rotating speed is 285 r / min, and the time is 2 minutes; finally, the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material is obtained, which is recorded as P2.

[0038] Example 2:

[0039] The alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material of the application comprises a soil material and an alkali activator. The soil material comprises in-situ soil with a mass ratio of 71%, 20% of slag, 5% of fly ash and 4% of sodium bentonite. The alkali activator dosage calculation formula is (mass of sodium silicate + mass of sodium hydroxide) / mass of soil material; the mass ratio of alkali activator is 7.2%; wherein the mass ratio of sodium silicate is 5%; the mass ratio of sodium hydroxide is 2.2%. The water mass ratio calculation formula is water mass / soil material mass, so the water mass ratio is 30%;

[0040] Step 1, after removing impurities, the in-situ soil is placed in an oven with a temperature of 60℃ for drying for more than 24 hours, then it is crushed and sieved with a 2mm sieve to obtain fine-grained in-situ soil;

[0041] Step 2, after stirring and mixing sodium silicate with a mass ratio of 5% and sodium hydroxide with a mass ratio of 2.2%, they are added to a container containing water with a mass ratio of 15%, sealed and then placed in a stirring heater, the stirring temperature is 60℃, the stirring time is 10 minutes, and the stirring speed is 500 r / min, after stirring, the alkali activator is obtained;

[0042] Step 3, put the fine-grained in-situ soil with a mass ratio of 71%, 20% of slag, 5% of fly ash and 4% of sodium bentonite into a blender for low-speed stirring and mixing, the rotating speed is 140 r / min, and the time is 2 minutes; then add the alkali activator and the remaining water with a mass ratio of 15%, first stir at a low speed, the rotating speed is 140 r / min, and the time is 2 minutes; then stir at a high speed, the rotating speed is 285 r / min, and the time is 2 minutes; finally, the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material is obtained, which is recorded as P4.

[0043] Example 3:

[0044] The alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material of the present application comprises a soil material and an alkali activator.

[0045] Step 1, after removing impurities, the in-situ soil is placed in a 60℃ oven for drying for more than 24 hours, then it is crushed and sieved with a 2mm sieve to obtain fine in-situ soil;

[0046] Step 2, 5% sodium silicate and 2.2% sodium hydroxide are stirred and mixed, then added to a container containing 15% water, sealed and placed in a stirring heater, the stirring temperature is 60℃, the stirring time is 10 minutes, and the stirring speed is 500r / min, and the alkali activator is obtained after stirring;

[0047] Step 3, 69% fine in-situ soil, 20% slag, 5% fly ash and 6% sodium-based bentonite are placed in a blender for low-speed stirring and mixing at a speed of 140r / min for 2 minutes, then the alkali activator and the remaining 15% water are added, first low-speed stirring at a speed of 140r / min for 2 minutes, then high-speed stirring at a speed of 285r / min for 2 minutes, and finally the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material is obtained, denoted as P6.

[0048] Example 4:

[0049] The alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material of the present application comprises a soil material and an alkali activator.

[0050] Step 1, after removing impurities, the in-situ soil is placed in a 60℃ oven for drying for more than 24 hours, then it is crushed and sieved with a 2mm sieve to obtain fine in-situ soil;

[0051] Step 2, the sodium silicate and 2.2% sodium hydroxide with a mass ratio of 5% are stirred and mixed, then added to a container containing 15% water, sealed and then placed in a stirring heater, the stirring temperature is 60 DEG C, the stirring time is 10 minutes, the stirring speed is 500 r / min, and the alkali activator is obtained after stirring;

[0052] Step 3, the fine-grained in-situ soil with a mass ratio of 67%, 20% of the slag, 5% of the fly ash and 8% of the sodium bentonite are put into a stirrer for low-speed stirring and mixing, the rotating speed is 140 r / min, and the time is 2 minutes; then the alkali activator and the remaining 15% water are added, first low-speed stirring is carried out, the rotating speed is 140 r / min, and the time is 2 minutes; then high-speed stirring is carried out, the rotating speed is 285 r / min, and the time is 2 minutes; finally, the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material is obtained, which is recorded as P8.

[0053] Example 5:

[0054] The alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material of the application comprises a soil material and an alkali activator. The soil material comprises 65% in-situ soil, 20% slag, 5% fly ash and 10% sodium bentonite. The alkali activator content calculation formula is (sodium silicate mass+ sodium hydroxide mass) / soil material mass; the mass ratio of the alkali activator is 7.2%; wherein the mass ratio of sodium silicate is 5%; the mass ratio of sodium hydroxide is 2.2%. The water mass ratio calculation formula is water mass / soil material mass, so the water mass ratio is 30%;

[0055] Step 1, the in-situ soil is dried in a 60 DEG C oven for more than 24 hours after removing impurities, then crushed and sieved with a 2mm sieve to obtain fine-grained in-situ soil;

[0056] Step 2, the sodium silicate and 2.2% sodium hydroxide with a mass ratio of 5% are stirred and mixed, then added to a container containing 15% water, sealed and then placed in a stirring heater, the stirring temperature is 60 DEG C, the stirring time is 10 minutes, the stirring speed is 500 r / min, and the alkali activator is obtained after stirring;

[0057] Step 3, put 65% of fine-grained in-situ soil, 20% of slag, 5% of fly ash and 10% of sodium bentonite into the mixer for low-speed stirring and mixing, the rotating speed is 140 r / min, and the time is 2 minutes; then add the alkali activator and the remaining 15% of water, first low-speed stirring, the rotating speed is 140 r / min, and the time is 2 minutes; then high-speed stirring, the rotating speed is 285 r / min, and the time is 2 minutes; finally, the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material is obtained, which is recorded as P10. Comparative Example 1:

[0058] The present application sets up a comparative example to intuitively compare the performance difference between the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material and the traditional vertical barrier wall material. The traditional vertical barrier wall material is represented by cement soil, and the main material is cement and in-situ soil. Mix 75% of fine-grained in-situ soil and 25% of cement with appropriate water, first low-speed stirring, the rotating speed is 140 r / min, and the time is 2 minutes; then high-speed stirring, the rotating speed is 285 r / min, and the time is 2 minutes; the obtained vertical barrier wall material is recorded as Comparative Example 1.

[0059] Performance detection:

[0060] After the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall materials of Examples 1-5 and the traditional vertical barrier wall material of Comparative Example 1 are placed in a standard curing box for 28 days, the following performance tests are carried out.

[0061] 1. Permeability test, the test method adopts the variable head permeability test in the Standard Test Methods for Soil (GB / T 50123-2019). According to the Vertical Barrier Technology Specification for Industrial Contaminated Sites (HG / T20715-2020), the permeability coefficient of the vertical barrier wall needs to meet the requirement of <1.0x10 -7 cm / s; the permeability coefficient results of each example and comparative example are shown in Table 1. Figure 2 .

[0062] 2. Compressive strength test, the test method adopts the compressive strength test in the Standard Test Methods for Physical and Mechanical Properties of Concrete (GB / T50081-2019). According to the Vertical Barrier Technology Specification for Industrial Contaminated Sites (HG / T20715-2020), the compressive strength of the vertical barrier wall needs to meet the requirement of not less than 0.1 MPa; the compressive strength results of each example and comparative example are shown in Table 2. Figure 3 .

[0063] 3. Barrier performance test: Barrier tests were conducted using typical inorganic pollutant Cd and organic pollutant 1,2-dichloroethylene from groundwater in chemical contaminated sites. Examples 1-5 and Comparative Example 1 were used to block Cd and 1,2-dichloroethylene contaminated solutions, as well as a combined Cd and 1,2-dichloroethylene contaminated solution. The barrier effects of each example and comparative example are shown in [reference needed]. Figure 4 .

[0064] Depend on Figure 2 The results show that, compared with traditional vertical barrier wall materials, the permeability coefficient of the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material of this invention is four orders of magnitude lower. The permeability coefficients of all embodiments meet the requirement of <1.0 × 10⁻⁶ in the "Technical Specification for Vertical Barriers of Industrial Contaminated Sites" (HG / T 20715-2020). -7 The requirement of cm / s demonstrates the excellent impermeability of the alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material of this invention. Traditional vertical barrier wall materials have permeability coefficients on the order of 10. -4 Pollutants can easily penetrate and break through the barrier wall to continue spreading, indicating poor impermeability. Figure 3 The results show that the compressive strength of all examples and control group 1 meets the requirement of "Technical Specification for Vertical Barriers of Industrial Contaminated Sites" (HG / T 20715-2020) that the compressive strength of vertical barrier walls should not be less than 0.1 MPa. However, the compressive strength of examples 1-5 is greater than that of control group 1, and it increases with the increase of bentonite content. The increase in compressive strength is more conducive to the application of vertical barrier walls in complex geological conditions and complex contaminated sites. Figure 4 The results show that all embodiments have excellent blocking effects, whether blocking Cd and 1,2-dichloroethylene contaminated liquid individually or blocking Cd and 1,2-dichloroethylene complex contaminated liquid, and the blocking ability is better than that of control group 1. It can be seen that the present invention has excellent blocking performance and can be applied to complex contaminated sites such as complex inorganic heavy metal pollution and inorganic-organic complex pollution, and can effectively block the migration and diffusion of pollutants.

[0065] The above embodiments are merely preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make various modifications and improvements without departing from the core spirit and legal protection scope of the present invention. Therefore, all technical solutions obtained by equivalent substitution or equivalent transformation should fall within the protection scope defined by the present invention.

Claims

1. A soil vertical barrier wall material, characterized by The soil body material is composed of in-situ soil, slag, fly ash and bentonite, and the mass percentage of the in-situ soil is 65-73%, the mass percentage of the slag is 15-25%, the mass percentage of the fly ash is 3-8%, and the mass percentage of the bentonite is 2-10%.

2. The soil vertical barrier wall material of claim 1, wherein The soil body material is composed of in-situ soil, slag, fly ash and bentonite, and the mass percentage of the in-situ soil is 65-73%, the mass percentage of the slag is 15-25%, the mass percentage of the fly ash is 3-8%, and the mass percentage of the bentonite is 2-10%.

3. The soil vertical barrier wall material of claim 1, wherein, The activity index of the slag is not less than S95, the grade of the fly ash is above II, and the bentonite is sodium-based bentonite.

4. The soil vertical barrier wall material of claim 1, wherein, The alkali activator is sodium silicate and sodium hydroxide.

5. The soil vertical barrier wall material of claim 4, wherein, The mass percentage of the alkali activator is 7.2%, the mass percentage of the sodium silicate is 5%, and the mass percentage of the sodium hydroxide is 2.2%.

6. The method of claim 1 wherein the soil vertical barrier wall material is prepared by The method comprises the following steps: Step 1, after the in-situ soil is removed of impurities, the in-situ soil is dried in an oven, then the in-situ soil is crushed and sieved to obtain fine in-situ soil; Step 2, sodium silicate and sodium hydroxide are stirred and mixed, then the mixture is added to a container containing water, the container is sealed and then placed in a stirring heater to continue stirring to obtain an alkali activator; Step 3, fine in-situ soil, slag, fly ash and bentonite are placed in a mixer in a certain proportion to mix, then the alkali activator is added, and the mixture is continuously stirred to obtain an alkali-activated slag and fly ash gel-bentonite-soil vertical barrier wall material.

7. The production method according to claim 6, wherein In step 1, the drying temperature is 60℃, and the drying time is more than 24 hours; the mesh size is 2mm.

8. The production method according to claim 6, wherein In step 2, the water is pure water, the stirring temperature is 60℃, the stirring time is 10 minutes, and the stirring speed is 500r / min.

9. The production method according to claim 6, wherein In step 3, the fine in-situ soil, slag, fly ash and sodium-based bentonite are mixed at a low speed, the rotating speed is 140r / min, and the time is 2 minutes.

10. The production method according to claim 6, wherein In step 3, after the alkali activator is added, the mixture is first stirred at a low speed, the rotating speed is 140r / min, and the time is 2 minutes; then the mixture is stirred at a high speed, the rotating speed is 285r / min, and the time is 2 minutes.

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