Curing method for inhibiting drying shrinkage cracking of cured sludge

Abstract

The invention discloses a curing method for inhibiting drying shrinkage cracking of cured sludge, and belongs to the technical field of crack prevention of cured sludge in geotechnical engineering. The artificial fine aggregate for inhibiting the cured sludge from drying shrinkage cracking is prepared from the following raw materials in parts by mass: 60 to 70 parts of gypsum powder, 20 to 30 parts of blast furnace slag, 2 to 10 parts of calcium carbide dust, 4 to 8 parts of cement and 0.5 to 1 part of sodium dodecyl benzene sulfonate. After the artificial fine aggregate disclosed by the invention is mixed into sludge, not only can the grading of the sludge be improved, but also the curing hydration reaction can be promoted to be continuously carried out by adsorbing free water through the porous structure, so that the dry shrinkage deformation of the cured sludge is compensated, and the dry shrinkage cracking resistance and the anti-seepage performance of the cured sludge can be improved. According to the invention, the artificial fine aggregate is prepared from a large mixing amount of industrial waste residue, and is mixed into the sludge to be cured, and the dry shrinkage deformation of the cured sludge is inhibited through grading improvement, free water adsorption, self volume expansibility and strength increase.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of geotechnical engineering solidification of silt and anti-cracking, and particularly relates to a solidification method for inhibiting dry shrinkage cracking of solidified silt. BACKGROUND

[0002] At present, in order to improve the water quality of rivers, ensure the flood discharge capacity of river channels, and ensure the smoothness of waterways and ports, large-scale river dredging and desilting work is required. Based on this, hundreds of millions of tons of river silt are generated every year, and its disposal has become a real problem that needs to be solved. Chemical solidification, as one of the effective means for treating river dredging silt, mainly changes the physical and chemical properties of silt by adding solidification materials and chemical agents to achieve the goals of improving engineering properties and protecting the environment. At the same time, solidified silt can be used as backfill material in embankment, road and other engineering, realizing the transformation of waste into treasure. However, due to the characteristics of high water content, high clay content and low permeability of river dredging silt, solidified silt is prone to dry shrinkage deformation under natural dry-wet cycle conditions, resulting in cracks in the internal structure of the solidified silt filling structure, which is difficult to meet the deformation and anti-seepage requirements of road, embankment, retaining wall and other engineering.

[0003] In order to inhibit the dry shrinkage cracking of solidified silt and reduce the number of cracks, methods such as adding fibers, gypsum and natural sand are usually used in engineering, but these methods still have some problems. Among them, the method of adding fibers is high in cost and not suitable for large-scale filling engineering, and the higher the fiber content, the more likely the fibers will agglomerate, making it difficult to uniformly disperse in the solidified silt, and the anti-cracking effect is poor; adding gypsum can effectively inhibit the dry shrinkage cracking of solidified silt, but improper amount will cause the solidified silt to swell and crack, and it is difficult to accurately control the amount in actual engineering; adding natural sand is to improve the gradation of high clay content silt to improve the anti-dry shrinkage cracking performance of solidified silt, but the exploitation of natural sand will damage the environment, and in the scene of plain soft soil area, the natural sand and stone materials are in short supply, often need to be purchased from other places, and the transportation cost is high. Therefore, how to design a low-cost river solidified silt dry shrinkage crack inhibition control method that fits the concept of low-carbon green development has broad application value. SUMMARY

[0004] The present application aims to provide a solidification method for inhibiting dry shrinkage cracking of solidified silt to solve the above problems in the background art. By mixing the artificial fine aggregate of the present application into the silt, not only the gradation of the silt can be improved, but also the free water can be adsorbed by the porous structure to promote the continuation of the solidification and hydration reaction, thereby compensating for the dry shrinkage deformation of the solidified silt, and improving the anti-dry shrinkage cracking performance and impermeability of the solidified silt.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions: One of the technical solutions of the present application: provide an artificial fine aggregate for inhibiting solidified silt dry shrinkage cracking, the raw materials include, by mass fraction: Gypsum powder 60~70 parts, blast furnace slag 20~30 parts, electric lime 2~10 parts, cement 4~8 parts and sodium dodecyl benzene sulfonate 0.5~1 part.

[0006] Preferably, the gypsum powder is industrial waste gypsum powder, and the type is phosphogypsum, desulfurization gypsum or fluorogypsum.

[0007] Preferably, the particle size of the gypsum powder is 0.5~709μm; the particle size of the blast furnace slag is 0.356~316μm; the particle size of the electric lime is 0.399~563μm.

[0008] Preferably, the cement is sulphoaluminate early strength cement.

[0009] The second technical solution of the present application: provide a preparation method of the above-mentioned artificial fine aggregate for inhibiting solidified silt dry shrinkage cracking, comprising the following steps: Mixing each raw material in water to obtain a slurry, curing to obtain a solidified block; Crushing the solidified block to obtain the artificial fine aggregate for inhibiting solidified silt dry shrinkage cracking.

[0010] Preferably, the water-cement ratio of the total mass of water and gypsum powder, blast furnace slag, electric lime and cement is 0.3~0.4.

[0011] Preferably, the curing time is 3~5 days.

[0012] Preferably, the unconfined compressive strength of the solidified block is >4.0MPa.

[0013] Preferably, the crushing is crushing to a particle size of 2~5mm.

[0014] The third technical solution of the present application: provide the application of the above-mentioned artificial fine aggregate for inhibiting solidified silt dry shrinkage cracking in the field of inhibiting solidified silt dry shrinkage cracking.

[0015] The fourth technical solution of the present application: provide a solidification method for inhibiting solidified silt dry shrinkage cracking, comprising the following steps: Mixing the above-mentioned artificial fine aggregate for inhibiting solidified silt dry shrinkage cracking into silt to obtain solidified silt to be cured, and then performing solidification treatment to obtain solidified silt with dry shrinkage cracking prevention performance.

[0016] Preferably, the mass ratio of the addition amount of the artificial fine aggregate to the dry mass of the silt is >1.0; The solidification treatment comprises the following steps: mixing gypsum powder, blast furnace slag, electric lime and lignin according to a mass ratio of 5-35:40-60:10-30:2-6 to obtain a solidification agent; and mixing the solidification agent with the sludge to be solidified according to a mixing amount of 60-100 kg / m 3 and curing.

[0017] Although there are schemes in the prior art that use sodium dodecyl benzene sulfonate as an air entraining agent to introduce air bubbles into concrete, the addition amount of the air entraining agent in these schemes is usually low, generally about 0.1%, and a too high addition amount will cause problems such as uneven bubble size, uneven distribution, and a significant decrease in the durability of the product. However, the present application designs an artificial fine aggregate with a significantly higher air bubble introduction ratio by significantly increasing the addition amount of the air entraining agent, significantly improves the micro-morphology of the artificial fine aggregate, and thus achieves more excellent product performance. Although a higher content of sodium dodecyl benzene sulfonate will also affect the strength and stability of the artificial fine aggregate itself, after being added as a mixing material for the sludge, the performance improvement effect achieved by the sodium dodecyl benzene sulfonate through the action of promoting hydration significantly covers the negative effects caused by the decrease in the stability of the fine aggregate, and thus the product performance of the solidified sludge can be improved.

[0018] The particle size of the crushed artificial fine aggregate cannot be too small, otherwise the porous structure introduced by the sodium dodecyl benzene sulfonate will be significantly destroyed; and the particle size cannot be too large, otherwise the interface bonding capacity of the artificial fine aggregate with the sludge matrix will be weakened, stress concentration points are easily formed at the contact interface, the overall strength and uniformity of the solidified body are reduced, and the artificial fine aggregate becomes the origin of crack initiation and aggravates the cracking risk. In addition, a too large particle size will also affect the volume expansion effect, and thus the dry shrinkage deformation of the sludge cannot be compensated.

[0019] The beneficial technical effects of the present application are as follows: A small amount of sodium dodecyl benzene sulfonate is added to the artificial fine aggregate designed in the present application, and the main purpose is to form a porous structure inside the crushed artificial fine aggregate through foaming, so that the free water in the sludge can be effectively adsorbed. After the artificial fine aggregate of the present application is mixed into the sludge, the gradation of the sludge can be improved by changing the addition amount, and the solidification and hydration reactions can be continuously promoted by adsorbing free water through the porous structure, so as to generate hydration products such as ettringite and cementitious products, and then the volume expansion and strength growth of the artificial fine aggregate are controlled to compensate for the dry shrinkage deformation of the solidified sludge, so as to improve the anti-dry-shrinkage-cracking performance and impermeability of the solidified sludge.

[0020] The preparation process of the present application is simple, the preparation efficiency is high, and the adaptability to complex construction environments of engineering sites is stronger. The preparation raw materials of the artificial fine aggregate of the present application are mainly industrial waste residues, which can solve the problem of storage of industrial waste residues, and the addition of a small amount of sulphoaluminate early strength cement can effectively improve the early strength of the solidified block, shorten the curing time to 3-5 days, and speed up the engineering progress.

[0021] The present application makes artificial fine aggregate by a large amount of industrial waste residue, and adds it into silt needing to be solidified, so as to inhibit the dry shrinkage deformation of the solidified silt by gradation improvement, adsorption of free water, self-volume expansion and strength growth. Compared with the conventional sand mixing solidification method, the volume shrinkage rate of the solidified silt improved based on the artificial fine aggregate can be reduced by more than 50%, and the preparation cost of the artificial fine aggregate is saved by 46-52% compared with purchasing natural sand, which has significant advantages in engineering, economic and environmental protection benefits. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0023] Figure 1 Flow chart of the solidification method for inhibiting dry shrinkage cracking of solidified silt of the present application; Figure 2 Inhibition principle diagram of dry shrinkage of the solidified silt with anti-dry shrinkage cracking performance of the present application; Figure 3 R1 and R5 in Example 2 after 7 days of maintenance, wherein (a) is R1 and (b) is R5. DETAILED DESCRIPTION

[0024] The various exemplary embodiments of the present application will now be described in detail, which should not be considered as limiting the present application, but should be understood as a more detailed description of some aspects, characteristics and embodiments of the present application. It should be understood that the terms described in the present application are only for describing the particular embodiments, and are not used to limit the present application.

[0025] In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value in the stated range, and any other stated value or intermediate value in the stated range, is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application pertains. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. It must be noted that as to application aspects not specifically covered herein, only routine operations are described, and are not the focus of the present application.

[0027] The terms “comprising,” “including,” “having,” “containing,” etc., used in this invention are all open-ended terms, meaning that they include but are not limited to.

[0028] The phosphogypsum used in the following embodiments and comparative examples of this invention was obtained from Anhui Sierte Fertilizer Technology Co., Ltd., with a particle size of 0.5~709μm; the blast furnace slag and steel plant calcium lime were obtained from Nanjing Iron & Steel Group, with particle sizes of 0.356~316μm and 0.399~563μm, respectively. The grade of the sulfoaluminate early-strength cement used was Yunyan brand 42.5 rapid-hardening sulfoaluminate cement. All raw materials used in the following embodiments and comparative examples of this invention are commercially available products.

[0029] Figure 1 This is a flowchart of the curing method for inhibiting the drying shrinkage and cracking of solidified sludge according to the present invention.

[0030] Figure 2 This is a schematic diagram illustrating the drying shrinkage inhibition principle of the solidified sludge with anti-drying shrinkage and cracking properties of the present invention.

[0031] Example 1 A method for preparing artificial fine aggregate for inhibiting drying shrinkage and cracking of solidified sludge, the specific steps of which are as follows: a. Add 5 tons of phosphogypsum, blast furnace slag, steel plant quicklime, and sulfoaluminate early-strength cement to a concrete mixer and mix evenly to obtain a mixture: The raw materials, by mass, are: 60 parts phosphogypsum, 30 parts blast furnace slag, 4 parts steel plant quicklime, 6 parts sulfoaluminate early-strength cement, and 1 part sodium dodecylbenzenesulfonate.

[0032] b. Add 1.5 tons of water to the mixture and stir thoroughly for 15 minutes to form a slurry.

[0033] c. Using a high-pressure mud pump, the slurry is pumped into a pre-excavated trench, which is 10m long, 3m wide, and 1.5m deep.

[0034] d. Repeat step ac until the trench is filled, then cover the mud surface with a geomembrane and cure (temperature 20±1℃, relative humidity 70%) for 3 days.

[0035] e. After 3 days of curing, use an excavator to crush the material using a crushing and screening bucket. By adjusting the spacing of the screening grid, the maximum particle size of the crushed fine aggregate is controlled at 2~5mm to obtain artificial fine aggregate.

[0036] Example 2 A method for inhibiting the drying shrinkage and cracking of solidified sludge, the specific implementation steps of which are as follows: a. The artificial fine aggregate prepared in Example 1 was mixed into river dredging silt with a moisture content of 119.32 wt%. The mass ratio of artificial fine aggregate to silt dry weight was set to 0:10 (i.e., no artificial fine aggregate), 2:8, 3:7, 4:6, 5:5, 6:4, and 7:3, respectively, resulting in silt to be solidified with fine particle contents of less than 0.075 mm of 86.32 wt%, 70.54 wt%, 62.18 wt%, 54.47 wt%, 46.86 wt%, 38.45 wt%, and 30.68 wt%, respectively.

[0037] b. Mix phosphogypsum, blast furnace slag, steel plant calcium lime and lignin in a mass ratio of 25:51.8:18.7:4.5 to obtain a composite curing agent.

[0038] c. Mix the composite curing agent with the sludge to be cured at a ratio of 100 kg / m³ 3 After mixing the admixtures thoroughly and evenly, pour the mixture into a mold to form a cylindrical sample with a diameter of 50 mm and a height of 100 mm. Place the sample in a standard curing chamber (temperature 20±1℃, relative humidity ≥95%) for 7 days to obtain solidified sludge with anti-drying shrinkage and cracking properties (referred to as R1, R2, R3, R4, R5, R6, and R7 according to the content of artificial fine aggregate from low to high).

[0039] Comparative Example 1 (only the artificial fine aggregate was replaced with natural sand) a. Natural sand (graded particle size of 2~5mm) was mixed into river dredging silt with a moisture content of 118.87wt%. The mass ratio of natural sand to silt dry weight was set to 4:6 and 7:3, respectively, to obtain two types of sand-mixed silt to be solidified, which were denoted as g1 and g2 respectively.

[0040] b. Mix phosphogypsum, blast furnace slag, steel plant calcium lime and lignin in a mass ratio of 25:51.8:18.7:4.5 to obtain a composite curing agent.

[0041] c. Mix the composite curing agent with g1 and g2 respectively at a ratio of 100 kg / m 3 After mixing the admixtures thoroughly and evenly, the mixture is poured into a mold to form a cylindrical sample with a diameter of 50 mm and a height of 100 mm. The sample is then placed in a standard curing chamber (temperature 20±1℃, relative humidity ≥95%) for 7 days to obtain sand-admixed solidified sludge (referred to as G1 and G2 respectively).

[0042] Comparative Example 2 (adjusting only the amount of sodium dodecylbenzenesulfonate added) (1) Four kinds of artificial fine aggregates were prepared by simply changing the amount of sodium dodecylbenzenesulfonate added in step a of Example 1 from 1 part by mass to 0 parts by mass (i.e., no sodium dodecylbenzenesulfonate added), 0.2 parts by mass, 0.5 parts by mass, and 1.5 parts by mass, respectively, and were denoted as A0, A0.2, A0.5 and A1.5.

[0043] (2) Artificial fine aggregates A0, A0.2, A0.5, and A1.5 (with a gradation particle size of 2-5 mm) were respectively mixed into river dredging silt with a moisture content of 119.45 wt%. The mass ratio of artificial fine aggregates to silt dry weight was set at 7:3. Four types of sand-mixed silt to be solidified were obtained, which were denoted as B0, B0.2, B0.5, and B1.5 respectively.

[0044] (3) Phosphogypsum, blast furnace slag, steel plant calcium lime and lignin are mixed in a mass ratio of 25:51.8:18.7:4.5 to obtain a composite curing agent.

[0045] (4) Mix the composite curing agent with B0, B0.2, B0.5, and B1.5 respectively at a ratio of 100 kg / m 3 After mixing the admixtures thoroughly and evenly, the mixture is poured into a mold to form a cylindrical sample with a diameter of 50 mm and a height of 100 mm. The sample is then placed in a standard curing chamber (temperature 20±1℃, relative humidity ≥95%) for 7 days to obtain sand-admixed solidified sludge (referred to as H1, H2, H3, and H4 respectively).

[0046] Comparative Example 3 (aggregate particle size adjusted only) (1) The solidified block in step e of Example 1 is crushed into artificial fine aggregates with a particle size of 0.075~2mm and 5mm~10mm, respectively, and denoted as J1 and J2.

[0047] (2) Artificial fine aggregates J1 and J2 were respectively added to river dredging silt with a moisture content of 118.12 wt%. The mass ratio of artificial fine aggregates to silt dry weight was set at 7:3. Two types of sand-mixed silt to be solidified were obtained, which were denoted as K. 0.075~2 K 5~10 .

[0048] (3) Phosphogypsum, blast furnace slag, steel plant calcium lime and lignin are mixed in a mass ratio of 25:51.8:18.7:4.5 to obtain a composite curing agent.

[0049] (4) Mix the composite curing agent with K respectively 0.075~2 K 5~10 According to 100kg / m 3The admixtures were mixed thoroughly and poured into a mold to form cylindrical samples with a diameter of 50 mm and a height of 100 mm. These samples were then cured in a standard curing chamber (temperature 20 ± 1℃, relative humidity ≥ 95%) for 7 days to obtain sand-admixed solidified silt (denoted as L). 0.075~2 L 5~10 ).

[0050] Effect verification 1. In accordance with GB / T 50123-2019 "Standard for Geotechnical Testing Methods", the volume shrinkage rate and compressive strength of the specimens in Example 2 were tested, and the test results are shown in Table 1.

[0051] Table 1. Test results of shrinkage and unconfined compressive strength of solidified sludge with different amounts of artificial fine aggregate. Table 1 shows that incorporating artificial fine aggregate into the silt significantly reduces the volume shrinkage rate of the solidified silt. Without artificial fine aggregate (R1), the final volume shrinkage rate of the solidified silt after 7 days of curing under natural drying conditions reaches as high as 23.6%, making it highly susceptible to drying shrinkage cracks. With increasing artificial fine aggregate content, the volume shrinkage rate of the solidified silt decreases significantly. When the ratio of artificial fine aggregate to dry silt is greater than 5:5 and the fine particle content of the graded improved silt is less than 50%, the volume shrinkage rate decreases to below 2.5%. Furthermore, with increasing artificial fine aggregate content, the unconfined compressive strength of the solidified silt after 7 days of curing also significantly increases. Without artificial fine aggregate, the unconfined compressive strength is 407.3 kPa; when the ratio of artificial fine aggregate to dry silt is greater than 5:5, the unconfined compressive strength exceeds 600 kPa.

[0052] Figure 3 The images show the surface cracks of R1 and R5 in Example 2 after 7 days of curing. In the images, (a) is R1 and (b) is R5.

[0053] Figure 3 In the comparison of surface cracks between R1 without artificial fine aggregate and R5 after artificial fine aggregate was added to the sludge, it can be seen that the surface cracks of the solidified sludge with artificial aggregate after drying shrinkage are significantly reduced.

[0054] 2. The volume shrinkage rate and compressive strength of the samples in Example 2 and Comparative Example 1 were tested, and the test results are shown in Table 2.

[0055] Table 2. Results of drying shrinkage and unconfined compressive strength tests on solidified sludge mixed with sand and artificial fine aggregate. Table 2 compares the drying shrinkage and unconfined compressive strength test results of sludge solidified with sand and artificial fine aggregate. The results show that when the ratio of sand to artificial fine aggregate is the same, the volume shrinkage rate of the solidified sludge with artificial fine aggregate is significantly reduced, by more than 50% compared to the sludge solidified with sand. Furthermore, the unconfined compressive strength after 7 days of curing is also significantly improved after adding artificial fine aggregate. These phenomena are mainly due to the strong water absorption of the porous structure of artificial fine aggregate, which also promotes secondary hydration reactions, promotes the formation of ettringite, and results in aggregate volume expansion and strength increase. In addition, phosphogypsum and steel mill calcium lime have ex-factory subsidies of about 25-30 yuan / ton, blast furnace slag 100-110 yuan / ton, sulfoaluminate early strength cement 260-280 yuan / ton, and sodium dodecylbenzene sulfonate 1700-2000 yuan / ton. Based on a water-cement ratio of 0.35, the raw material cost of artificial fine aggregate is 62-70 yuan / ton. Adding labor and equipment costs of 10 yuan / ton, the total cost is 72-80 yuan / ton, which saves 46-52% compared to purchasing natural sand (130-200 yuan / ton).

[0056] 3. The volume shrinkage rate and compressive strength of the samples in Example 2 and Comparative Example 2 were tested, and the test results are shown in Table 3.

[0057] Table 3. Results of drying shrinkage and compressive strength tests on solidified sludge with different sodium dodecylbenzenesulfonate content. Table 3 compares the drying shrinkage and unconfined compressive strength test results of solidified sludge under different sodium dodecylbenzenesulfonate dosages. The results show that the addition of sodium dodecylbenzenesulfonate significantly affects the volume shrinkage and strength characteristics of solidified sludge with artificial fine aggregate during preparation. For artificial fine aggregate prepared without sodium dodecylbenzenesulfonate, the volume shrinkage rate and unconfined compressive strength after 7 days of curing of the improved solidified sludge are higher than those of conventional sand-mixed solidified sludge. With the addition of sodium dodecylbenzenesulfonate and its dosage, the increased water absorption and more vigorous secondary hydration reaction in the artificial fine aggregate lead to enhanced aggregate expansion and strength, resulting in reduced volume shrinkage and increased unconfined compressive strength of the solidified sludge after 7 days of curing. However, when the sodium dodecylbenzenesulfonate content exceeds the critical value, although the water absorption of the artificial fine aggregate is slightly enhanced, the strength is significantly reduced, resulting in volume shrinkage of the solidified sludge with artificial fine aggregate and a decrease in the unconfined compressive strength after 7 days of curing.

[0058] 4. The volume shrinkage rate and compressive strength of the samples in Example 2 and Comparative Example 3 were tested, and the test results are shown in Table 3.

[0059] Table 4. Results of drying shrinkage and compressive strength tests on solidified sludge with different aggregate gradations and particle sizes. Table 4 compares the results of drying shrinkage and unconfined compressive strength tests on solidified sludge with different artificial fine aggregate gradations. The results show that the gradation size of the artificial fine aggregate has a significant impact on the volume shrinkage and strength characteristics of the solidified sludge. When the gradation size of the artificial fine aggregate is too small, the skeletal support of the aggregate is significantly weakened, and the porous structure introduced by sodium dodecylbenzene sulfonate is destroyed, reducing water absorption capacity. This leads to a decrease in the volume shrinkage resistance and strength of the solidified sludge. When the gradation size is too large, it weakens the interfacial bonding between the aggregate and the sludge matrix, forming stress concentration points at the contact interface, thereby reducing the overall strength and uniformity of the solidified body. Furthermore, excessively large particle sizes also affect the volume expansion effect of the aggregate, leading to a decrease in the ability to compensate for the drying shrinkage deformation of the sludge and a reduction in its strength.

[0060] In summary, the curing method for inhibiting drying shrinkage and cracking of solidified sludge provided by this invention can effectively reduce the volume shrinkage and deformation of solidified sludge during the drying process and improve the strength of solidified sludge. Furthermore, compared with traditional methods such as sand mixing, it not only effectively inhibits drying shrinkage and cracking of solidified sludge but also significantly reduces engineering costs.

[0061] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An artificial fine aggregate for inhibiting the drying shrinkage and cracking of solidified sludge, characterized in that, Raw materials, by mass parts, include: The ingredients are 60-70 parts gypsum powder, 20-30 parts blast furnace slag, 2-10 parts carbohydrate, 4-8 parts cement, and 0.5-1 parts sodium dodecylbenzene sulfonate.

2. The artificial fine aggregate for inhibiting drying shrinkage and cracking of solidified sludge according to claim 1, characterized in that, The gypsum powder has a particle size of 0.5~709μm; the blast furnace slag has a particle size of 0.356~316μm; and the carbide lime has a particle size of 0.399~563μm.

3. The artificial fine aggregate for inhibiting drying shrinkage and cracking of solidified sludge according to claim 1, characterized in that, The cement is sulfoaluminate early-strength cement.

4. A method for preparing artificial fine aggregate for inhibiting drying shrinkage and cracking of solidified sludge as described in any one of claims 1-3, characterized in that, Includes the following steps: The raw materials are mixed in water to obtain a slurry, which is then cured to obtain a solidified block. The solidified block is crushed to obtain the artificial fine aggregate used to inhibit the drying shrinkage and cracking of solidified sludge.

5. The preparation method according to claim 4, characterized in that, The water-cement ratio of the total mass of water, gypsum powder, blast furnace slag, carbide lime, and cement is 0.3 to 0.

4.

6. The preparation method according to claim 4, characterized in that, The maintenance period is 3 to 5 days.

7. The preparation method according to claim 4, characterized in that, The crushing process involves crushing the particles to a size of 2-5 mm.

8. The application of the artificial fine aggregate for inhibiting drying shrinkage cracking of solidified sludge as described in any one of claims 1-3 in the field of inhibiting drying shrinkage cracking of solidified sludge.

9. A method for inhibiting the drying shrinkage and cracking of solidified sludge, characterized in that, Includes the following steps: The artificial fine aggregate for inhibiting drying shrinkage and cracking of solidified sludge as described in any one of claims 1-3 is added to the sludge to be solidified, and then solidification treatment is carried out to obtain solidified sludge with anti-drying shrinkage and cracking properties.

10. The curing method according to claim 9, characterized in that, The ratio of the amount of artificial fine aggregate added to the dry weight of the silt is >1.0; The solidification treatment includes the following steps: mixing gypsum powder, blast furnace slag, carbide lime, and lignin in a mass ratio of 5~35:40~60:10~30:2~6 to obtain a solidifying agent; and mixing the solidifying agent with the sludge to be solidified at a ratio of 60~100 kg / m³. 3 Mix the appropriate amount and then cure.

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