Shield muck foundation wall post-grouting material and preparation method thereof

Abstract

The invention discloses a shield muck-based wall post-grouting material and a preparation method thereof, and belongs to the technical field of solid waste material reutilization and grouting material preparation, the grouting material comprises the following components by weight: 5.2-5.7 parts of earth pressure balance shield muck, 0.1-0.3 part of an adsorbent, 0.4-1 part of an alkali excitation material, 2.75-3.5 parts of water, and 0-0.03 part of an additive; the adsorbent is a product obtained by carbonizing concrete micro powder in a carbon dioxide atmosphere; the alkali excitation technology is adopted, the novel low-carbon inorganic curing agent is compounded with the compound shield muck and the carbonized micro-powder adsorbent, the alkali excitation grouting material with the high solid waste ratio is developed, the muck generated by shield is fully utilized for resource utilization, and the prepared grouting material is high in early strength, good in fluidity and high in solid waste content. And harmful substances in the shield muck can be effectively adsorbed, and pollution caused in the muck transferring process is avoided.

Description

Technical Field

[0001] The present invention relates to the technical fields of solid waste material reuse and grouting material preparation, and specifically relates to a shield muck-based post-grouting material and a preparation method thereof. Background Art

[0002] In the engineering muck (including slurry) in coastal cities, the muck generated by underground pipeline construction accounts for a relatively large proportion. In subway construction, the shield method has become the preferred method for rail transit construction due to its construction safety, high efficiency, little impact on ground traffic and river navigation, small environmental hazards, and resistance to climate change. However, the shield method of construction will generate a large amount of shield muck. The large increment and stockpile of shield muck and its difficult disposal are the biggest problems faced in the disposal of construction waste in Guangzhou.

[0003] Although physical screening of shield muck can obtain value-added crushed stones and medium to coarse sand, and a relatively mature industrial chain has been formed. However, the soil and sludge components generated by earth pressure shields are complex and difficult to treat, mainly composed of siltstone, strong (medium) weathered rock, and clay minerals, etc., and clay is the main phase among them. The sludge contains harmful substances such as the high molecular polymers (such as foaming agents, flocculants, etc.) added during the slurry shield process, and construction waste recycling enterprises often need to additionally add high molecular polymers and other chemical reagents during the pretreatment of washing and screening shield muck to achieve the purpose of quickly cleaning the sand and gravel, which makes the sludge composition more complex. The traditional disposal methods mainly rely on open stacking and landfill, which not only consume a large amount of land but also cause serious environmental crises.

[0004] Using the muck generated by the shield to prepare post-grouting materials is an effective way of muck resource utilization. However, the presence of organic matter in earth pressure shield muck will affect the performance of the cementitious material and limit the amount of muck used. This is because traditional post-grouting materials still mainly use cement and fly ash as the main cementitious materials. The hydration products of cement mainly include Ca(OH)2 and C-S-H gels with a high Ca / Si ratio. In a water-rich environment, alkaline substances such as Ca(OH)2 are easily leached out, which in turn leads to the decomposition of C-S-H gels, thereby reducing the structural stability and water erosion resistance of the cement-based grouting material. In addition, how to avoid the adverse effects of these additives on the performance of the prepared post-grouting material and prevent the secondary leaching of additives after the formation of solidified soil, which causes pollution to the soil and water body, is also one of the key problems to be solved in the utilization of earth pressure shield muck. Summary of the Invention

[0005] Aiming at the problem that shield slag tailings have complex components and contain various types of difficult-to-degrade polymers, the present invention provides a shield slag foundation wall rear grouting material and a preparation method thereof. The grouting material focuses on solving the shield slag tailings on site and fully utilizes the slag generated by the shield for resource utilization. The prepared grouting material has high early strength and good fluidity, and can effectively absorb harmful substances in the shield slag, thereby avoiding pollution caused by the slag transportation process.

[0006] The purpose of the present invention is achieved by the following technical solutions: A shield slag foundation wall back grouting material, comprising the following components in parts by weight: 5.2-5.7 parts of earth pressure balance shield slag, 0.1-0.3 parts of adsorbent, 0.4-1 parts of alkali-activated material, 2.75-3.5 parts of water, 0-0.03 parts of additives; The adsorbent is a product of carbonization of concrete powder in a carbon dioxide atmosphere; the concrete powder is obtained by grinding hydrated cement, such as grinding cement into powder after natural curing, grinding waste concrete into powder, or grinding waste concrete with coarse aggregate and / or fine aggregate into powder.

[0007] In some preferred embodiments, the earth pressure balance shield slag includes sand and mud cake; the sand is a product with a particle size of <0.5 mm obtained by sending the earth pressure balance shield slag to a screening machine after primary screening, primary screening and secondary screening, and then screening again; wherein, the earth pressure balance shield slag is screened twice after passing through the secondary screen, and passes through 1.18 mm and 0.5 mm sieves respectively; the mud cake is a product obtained by obtaining sand and mud after the earth pressure balance shield slag is screened through gravel, and then the mud is pumped into a plate and frame filter press for filtration and dehydration.

[0008] In some preferred embodiments, the water content of the sand and the mud cake is 22%-52%; the organic matter content is 3-33 g / kg.

[0009] In some preferred embodiments, the mud cake has a SiO2 content of 40%-50%, an Al2O3 content of 13%-30%, and a CaO content of 0%-18%.

[0010] In some preferred embodiments, the base-activated material comprises the following components by weight: 80 parts of blast furnace slag, 10-20 parts of Portland cement, 10-15 parts of alkali activator; 0-5 parts of quicklime; 0-5 parts of slaked lime.

[0011] In some preferred embodiments, the blast furnace slag is S90 grade slag with a particle size of 0.4-100 µm.

[0012] In some preferred embodiments, the alkali activator comprises a mixture of sodium hydroxide solution, sodium silicate and sodium sulfate, with a modulus of 1 - 2 and a Na2O content of 3 - 6 wt%.

[0013] In some preferred embodiments, the additive comprises a solid water reducer, and the solid water reducer is a polycarboxylate water reducer or a naphthalene water reducer; the polycarboxylate water reducer is a commercially available product, with its chemical composition mainly being modified polycarboxylate, a density of 0.4 - 0.6 g / cm 3 , a pH of 9 - 12, a total chloride ion content of ≤0.1%, and an alkali content of ≤3%; the naphthalene water reducer is a commercially available product, with its main chemical composition being naphthalene sulfonate formaldehyde condensate and a pH of 7 - 9.

[0014] In some preferred embodiments, the carbonization conditions of the concrete powder are: humidity 70 - 95%, temperature 20 ± 10°C, carbon dioxide concentration 20 ± 5%, and carbonization time 3 - 7 days.

[0015] The second aspect of the present invention lies in providing a preparation method of the shield muck-based backfill grouting material, comprising the following steps: (1) Adding water to the untreated slag sand and performing grading sieving, passing through 1.18 mm and 0.5 mm sieves respectively to obtain sandy soil with a particle size <0.5 mm; (2) Pressing and filtering the slurry to obtain a mud cake; (3) Stirring and mixing the sandy soil, mud cake and water in proportion to obtain a slurry; (4) Adding the adsorbent, alkali activation material and additive in proportion, and stirring and mixing to obtain the grouting material, which can then be transported, poured and cured.

[0016] In some preferred embodiments, the density of the grouting material is 1.85 - 1.95 g / mL and the fluidity is 220 - 250 mm.

[0017] The beneficial effects of the present invention are as follows: (1) The present invention combines a new type of low-carbon inorganic curing agent with shield muck to develop an alkali-activated grouting material with a high proportion of solid waste. It not only effectively utilizes shield construction waste, but also fully exerts the gelling potential of industrial by-products, realizing the efficient reuse of waste resources. The grouting material prepared thereby not only reduces the usage amount of traditional cement, reduces carbon emissions during the production process, but also effectively realizes the resource utilization of solid waste and environmental protection.

[0018] (2) The present invention makes use of the complementary advantages of different shield muck in terms of particle size distribution through the combination of two types of muck. By optimizing the particle gradation and the combination of active components, the fluidity and stability of the slurry are improved, water bleeding will not occur, and it can also promote the physical filling effect and chemical reaction activity inside the slurry, thereby forming a denser and higher-strength hardened structure. By adopting this compounding strategy, the dosage of shield muck in the grouting material can be significantly increased, effectively reducing the dependence on traditional cementitious materials, reducing the material cost and environmental burden, and promoting the large-scale disposal and high-value resource recycling of shield construction waste.

[0019] (3) After carbonization modification in a carbon dioxide atmosphere, the concrete micropowder forms a structure with an ultra-high specific surface area, hierarchical porous structure, and rich surface chemical properties, enabling it to have prominent dual functions of physical adsorption and chemical adsorption. It can effectively capture and fix organic pollutants in shield muck, promoting the selective adsorption of pollutants, and thus significantly reducing the organic matter content in the muck. In addition, through various action mechanisms such as electrostatic interaction, hydrogen bonding, van der Waals force, and complexation, the carbonized micropowder enhances its comprehensive removal performance for complex organic pollutants. This process not only improves the environmental safety of shield muck but also provides a good foundation for its further solidification, stabilization, and resource utilization. Brief Description of the Drawings

[0020] The present invention will be further described with reference to the accompanying drawings. However, the embodiments in the drawings do not constitute any limitation to the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the following drawings.

[0021] Figure 1 It is a schematic diagram of the preparation process of the shield muck-based post-grouting material described in Embodiment 1 of the present invention; Figure 2 It is a physical diagram of the casting part of the shield muck-based post-grouting material described in Embodiment 1 of the present invention; Figure 3 It is a comparison diagram of the fluidity results of the grouting materials described in Embodiments 1-3 and Comparative Examples 1-3 of the present invention; Figure 4 It is a comparison diagram of the 3d compressive strength results of the grouting materials described in Embodiments 1-3 and Comparative Examples 1-3 of the present invention; Figure 5 It is a comparison diagram of the apparent setting results of the grouting materials described in Embodiments 1-3 and Comparative Examples 1-3 of the present invention; Figure 6 It is a comparison diagram of the final setting time results of the grouting materials described in Embodiments 1-3 and Comparative Examples 1-3 of the present invention; Figure 7 It is a comparison diagram of the chemical oxygen demand results before and after curing of the grouting materials described in Embodiments 1-3 of the present invention. Specific Embodiments

[0022] The present invention will be further described in conjunction with the following embodiments.

[0023] Embodiment 1 A post - grouting material for the shield muck base wall is composed of the following components by weight: 84.20 parts of sandy soil; 21.05 parts of mud cake; 54.74 parts of water; 4.0 parts of adsorbent; 12.8 parts of blast furnace slag; 3.20 parts of portland cement; 0.8 part of quicklime; 2.24 parts of alkali activator; 0.2 part of water - reducing agent; The sandy soil is the sandy soil with a particle size < 0.5mm obtained by adding water and sieving the shield muck; the mud cake is obtained by pumping the slurry into a plate - and - frame filter press for pressure filtration and dehydration after the earth pressure balance shield muck is screened by gravel. The SiO2 content of the mud cake is 42.77%, the Al2O3 content is 18.18%, and the CaO content is 8.33%; the water contents of the sandy soil and the mud cake are 36.42% and 33.27% respectively; the organic matter content is 9.1g / kg; The adsorbent is the product of carbonizing concrete powder in a carbon dioxide atmosphere. The carbonization conditions of the concrete powder are: humidity 95%, temperature 20°C, carbon dioxide concentration 20%, and carbonization time 7 days; the concrete powder is obtained by grinding the hydrated cement and is the powder ground from the cement after natural curing; The blast furnace slag is S90 - grade slag with a particle size of 0.4 - 100µm; The alkali activator includes a mixture of sodium hydroxide solution, sodium silicate and sodium sulfate, with a modulus of 1.2 and a Na2O content of 4wt%; The water - reducing agent is a commercially available polycarboxylate water - reducing agent or naphthalene - based water - reducing agent; the main chemical component of the polycarboxylate water - reducing agent is modified polycarboxylate, with a density of 0.4 - 0.6g / cm 3 , pH between 9 - 12, total chloride ion content ≤ 0.1%, alkali content ≤ 3%; the main chemical component of the naphthalene - based water - reducing agent is naphthalene sulfonate formaldehyde condensate, with a pH between 7 - 9; The preparation method of the post - grouting material for the shield muck base wall includes the following steps: (1) Add water to the untreated slag sand and perform classification sieving, passing through 1.18mm and 0.5mm sieves respectively to obtain sandy soil with a particle size < 0.5mm, and measure the water content; (2) The slurry is dewatered by pressure filtration to obtain a mud cake, and the physical and chemical properties such as the moisture content, mineral composition, and particle size distribution of the mud cake are tested; (3) The sand soil, the mud cake and water are stirred and mixed in proportion to obtain a slurry; (4) The adsorbent, the alkali activator, and the water reducer are added in proportion and stirred and mixed for 4 min to obtain the grouting material; (5) The grouting material is poured into a mold, demolded after curing to the specified time, and cured in a standard curing box.

[0024] The density of the grouting material is 1.91 g / mL, and the fluidity is 236.25 mm.

[0025] Example 2 A shield muck-based post-grouting material, by weight, consists of the following components: 73.3 parts of sand soil; 30.82 parts of mud cake; 55.87 parts of water; 2.03 parts of adsorbent; 10.91 parts of blast furnace slag; 2.73 parts of portland cement; 2.05 parts of alkali activator; 0.4 part of water reducer; The sand soil is sand soil with a particle size <0.5 mm obtained by adding water and sieving shield muck; the mud cake is the mud cake obtained by pumping the slurry into a plate and frame filter press for pressure filtration and dehydration after the earth pressure balance shield muck is screened by gravel. The SiO2 content of the mud cake is 40.64%, the Al2O3 content is 15.53%, and the CaO content is 12.69%; the moisture contents of the sand soil and the mud cake are 32.56% and 24.73% respectively; the organic matter content is 30.65 g / kg; The adsorbent is the product of carbonizing concrete powder in a carbon dioxide atmosphere. The carbonization conditions of the concrete powder are: humidity 90%, temperature 20 °C, carbon dioxide concentration 25%, and carbonization time 7 days; the concrete powder is obtained by grinding hydrated cement and is ground into powder from waste concrete; The blast furnace slag is S90 grade slag with a particle size of 0.4 - 100 µm; The alkali activator includes a mixture of sodium hydroxide solution, sodium silicate and sodium sulfate, with a modulus of 1.2 and a Na2O content of 5 wt%; The water reducer is a commercially available polycarboxylate water reducer or naphthalene-based water reducer; the chemical composition of the polycarboxylate water reducer is mainly modified polycarboxylate, with a density of 0.4 - 0.6 g / cm 3, the pH is 9 - 12, the total chloride ion content is ≤0.1%, and the alkali content is ≤3%; the main chemical component of the naphthalene-based water reducer is naphthalene sulfonate formaldehyde condensate, and the pH is 7 - 9; The preparation method of the shield muck-based grouting material after lining includes the following steps: (1) Add water to the untreated slag sand for grading and sieving, sieve through 1.18 mm and 0.5 mm sieves respectively to obtain sandy soil with a particle size <0.5 mm, and measure the moisture content; (2) Press-filter the slurry to obtain a mud cake, and test the physical and chemical properties such as the moisture content, mineral composition, and particle size distribution of the mud cake; (3) Stir and mix the sandy soil, mud cake and water in proportion to obtain a slurry; (4) Add the adsorbent, the alkali activator and the water reducer in proportion, and stir and mix for 4 minutes to obtain the grouting material; (5) Pour the grouting material into a mold, demold after curing to the specified time, and cure it in a standard curing box.

[0026] The density of the grouting material is 1.88 g / mL, and the fluidity is 241.75 mm.

[0027] Example 3 A shield muck-based grouting material after lining, by weight, consists of the following components: Sandy soil 85.21 parts; Mud cake 18.80 parts; Water 55.99 parts; Adsorbent 3.89 parts; Ground granulated blast-furnace slag 13.91 parts; Portland cement 2.54 parts; Alkali activator 2.61 parts; Water reducer 0.4 part; The sandy soil is sandy soil with a particle size <0.5 mm obtained by adding water and sieving the shield muck; the mud cake is the mud cake obtained by pumping the slurry into a plate and frame filter press for pressure filtration and dehydration after screening the earth pressure balance shield muck. The SiO2 content of the mud cake is 42.56%, the Al2O3 content is 13.94%, and the CaO content is 17.98%; the moisture contents of the sandy soil and the mud cake are 39.47% and 23.92% respectively; the organic matter content is 3.27 g / kg; The adsorbent is the product of carbonizing concrete powder in a carbon dioxide atmosphere. The carbonization conditions of the concrete powder are: humidity 85%, temperature 30 °C, carbon dioxide concentration 20%, and carbonization time 7 days; the concrete powder is obtained by grinding hydrated cement into powder by grinding waste concrete with coarse aggregate and / or fine aggregate; The blast furnace slag is S90 grade slag with a particle size of 0.4 - 100 µm; The alkali activator includes a mixture of sodium hydroxide solution, sodium silicate and sodium sulfate, with a modulus of 1.2 and a Na2O content of 4 wt%; The water reducer is a commercially available polycarboxylate water reducer or naphthalene - based water reducer; the chemical composition of the polycarboxylate water reducer is mainly modified polycarboxylate, with a density of 0.4 - 0.6 g / cm 3 , a pH of 9 - 12, a total chloride ion content ≤ 0.1%, and an alkali content ≤ 3%; the main chemical composition of the naphthalene - based water reducer is naphthalene sulfonate formaldehyde condensate, with a pH of 7 - 9; The preparation method of the shield muck - based post - grouting material includes the following steps: (1) Add water to the untreated slag sand and perform classification sieving, passing through 1.18 mm and 0.5 mm sieves respectively to obtain sandy soil with a particle size < 0.5 mm, and measure the water content; (2) Press - filter the slurry to obtain a mud cake, and test the physical and chemical properties of the mud cake such as water content, mineral composition and particle size distribution; (3) Stir and mix the sandy soil, mud cake and water in proportion to obtain a slurry; (4) Add the adsorbent, the alkali activation material and the water reducer in proportion, and stir and mix for 4 min to obtain the grouting material; (5) Pour the grouting material into a mold, demold after curing to the specified time, and place it in a standard curing box for curing.

[0028] The density of the grouting material is 1.75 g / mL and the fluidity is 280 mm.

[0029] Comparative Example 1 A grouting material uses dry - powder mortar, with shield - recovered sand as the main raw material, and fly ash, portland cement and bentonite as cementitious materials. Among them, the contents of each component are as follows: The sandy soil with a particle size < 0.5 mm of the shield - recovered sand is 760 g; Fly ash 135 g; Portland cement 125 g; Bentonite 20 g; Water 480 g; Then prepare the grouting material according to the following steps: 1) Mix the ash body and water in proportion and stir thoroughly for 4 min to obtain a fresh slurry; 2) Pour the slurry into a mold, demold after curing to the specified time, and place it in a standard curing box.

[0030] Comparative Example 2 A grouting material, which is the same as that in Example 1, except that the composition of the grouting material does not contain an adsorbent.

[0031] The density of the grouting material is 1.84 g / mL, and the fluidity is 248.5 mm.

[0032] Comparative Example 3 A grouting material, which is the same as that in Example 3, except that the sand in the composition of the grouting material is replaced with mud cake in equal amount.

[0033] The density of the grouting material is 1.97 g / mL, and the fluidity is 170.25 mm.

[0034] Measure and calculate the fluidity of the grouting materials obtained from Examples 1-3 and Comparative Examples 1-3; use a Vicat apparatus to conduct an apparent setting test and a final setting time test on the samples; use an INSTRON 5984 universal testing machine to conduct mechanical property tests, where the compression strength test has a loading rate of 0.5 kN / s. All data is transmitted to a computer equipped with dedicated acquisition software.

[0035] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention, rather than limiting the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A post - grouting material for the back of the shield muck base wall, characterized in that, By weight parts, it comprises the following components: Earth pressure balance shield muck: 5.2 - 5.7 parts, adsorbent: 0.1 - 0.3 part, alkali-activated material: 0.4 - 1 part, water: 2.75 - 3.5 parts, additive: 0 - 0.03 part; Wherein, the adsorbent is the product of carbonization of concrete powder in a carbon dioxide atmosphere.

2. The post - grouting material for the shield muck base wall according to claim 1, characterized in that, The earth pressure balance shield muck comprises sand and mud cake.

3. The post - grouting material for the back of the shield muck - based wall according to claim 2, characterized in that, The water content of the sand and the mud cake is 22% - 52%; the organic matter content is 3 - 33 g / kg.

4. A post - grouting material for the back of the shield muck base wall according to claim 1, characterized in that The SiO2 content of the mud cake is 40% - 50%, the Al2O3 content is 13% - 30%, and the CaO content is 0% - 18%.

5. The post - grouting material for the shield muck base wall according to claim 1, wherein, By weight parts, the alkali-activated material comprises the following components: Blast furnace slag: 80 parts, portland cement: 10 - 20 parts, alkali activator: 10 - 15 parts; quicklime: 0 - 5 parts; hydrated lime: 0 - 5 parts.

6. The post - grouting material for the shield muck base wall according to claim 5, characterized in that, The blast furnace slag is S90 grade slag with a particle size of 0.4 - 100 µm.

7. The post-grouting material for the shield muck-based wall according to claim 1, wherein The additive comprises a solid water reducer, and the solid water reducer is a polycarboxylate water reducer or a naphthalene series water reducer.

8. A post-grouting material for the back of the shield muck base wall according to claim 1, characterized in that, The conditions of carbonization are: humidity 70 - 95%, temperature 20 ± 10°C, carbon dioxide concentration 20 ± 5%, and carbonization time 3 - 7 days.

9. The preparation method of a post-grouting material for the back of the shield muck-based wall according to any one of claims 1-8, characterized in that, It comprises the following steps: (1) Adding water to the untreated slag sand and classifying and sieving it through 1.18 mm and 0.5 mm sieves respectively to obtain sand with a particle size <0.5 mm; (2) Pressing and filtering the slurry to obtain a mud cake; (3) Stirring and mixing the sand, mud cake and water in proportion to obtain a slurry; (4) Adding the adsorbent, the alkali-activated material and the additive in proportion, and stirring and mixing to obtain the grouting material.

10. The preparation method according to claim 9, characterized in that, The density of the grouting material is 1.85 - 1.95 g / mL, and the fluidity is 220 - 250 mm.

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