Gradient concrete plate based on waste incineration bottom slag and preparation method of gradient concrete plate

Abstract

The invention relates to the technical field of concrete slabs, in particular to a gradient concrete slab based on waste incineration bottom slag and a preparation method thereof.The preparation method comprises the following preparation steps that S1, the waste incineration bottom slag, a modified curing agent and aggregate are put into a stirrer to be stirred, and a dry mixture is obtained; s2, uniformly mixing water, a water reducing agent and the modified emulsion, and slowly adding the mixture into the dry mixture; s3, adding polypropylene fibers and steel fibers into the slurry, stirring, pouring into a mold, and slicking the surface to obtain a concrete material; and S4, the concrete material is placed on a vibration table and passes through a mode A, a mode B and a mode C, standing is conducted after vibration is finished, a plastic film covers the concrete material, the concrete material is placed at the room temperature for 20-24 h and then demolded, the concrete material is placed in a curing box for curing, and the gradient concrete plate based on the waste incineration bottom slag is obtained. Through the synergistic effect of the modification auxiliary agent, the modified emulsion and the modified curing agent, the defect that durability is poor due to the fact that the bottom slag is light and porous is effectively overcome, and synchronous improvement of long-term stability and impermeability is achieved.

Description

Technical Field

[0001] This invention relates to the field of concrete slab technology, specifically to a gradient concrete slab based on waste incineration bottom ash and its preparation method. Background Technology

[0002] With the acceleration of urban modernization, waste incineration has become one of the main methods of urban solid waste treatment, but this has also generated a large amount of waste incineration ash (hereinafter referred to as "ash"). The storage and disposal of this ash is becoming increasingly prominent, not only occupying a large amount of land resources but also potentially causing secondary pollution to the environment. Currently, the resource utilization of ash is mainly concentrated in the field of building materials, such as using it as a substitute for sand and gravel aggregates in low-value-added products like bricks and roadbed materials. However, ash particles have inherent characteristics such as being lightweight, porous, having low strength, and high water absorption. Directly using them in concrete preparation would significantly reduce the mechanical properties and durability of the material, limiting its application in high-performance building materials.

[0003] Bottom slag particles are typically lightweight and porous, with low strength and high water absorption, which is detrimental to improving the strength and durability of concrete. However, as a lightweight aggregate, its easily deformable properties after impact can be utilized as an inexpensive energy-absorbing material. Traditional artificial lightweight aggregates also have similar functions, but they are expensive and uneconomical. Although bottom slag has certain energy-absorbing properties as a lightweight aggregate and can be used as an impact-absorbing material, its high water absorption and low strength lead to poor concrete workability, easy cracking, and insufficient long-term stability. In contrast, artificial lightweight aggregates (such as expanded clay) have excellent performance, but their high production cost and poor economic efficiency make large-scale promotion difficult. Therefore, developing a preparation method that can effectively utilize bottom slag, overcome its performance defects, and improve the overall performance of concrete has become an important research direction in the fields of waste resource utilization and building materials. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a gradient concrete slab based on waste incineration bottom ash and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing gradient concrete slabs based on waste incineration bottom ash includes the following preparation steps: S1. By weight, put 25-30 parts of waste incineration bottom ash, 5-8 parts of modified curing agent and 133-160 parts of aggregate into a mixer and dry mix at a speed of 150-200 r / min for 3-5 minutes to obtain dry mix. S2. Mix 45-50 parts water, 1-1.5 parts water-reducing agent and 15-20 parts modified emulsion evenly, slowly add to dry mix, and stir at 150-200 r / min for 5-10 min until the slurry is uniform. S3. Add 0.3-0.5 parts of polypropylene fiber and 1.5-2 parts of steel fiber to the slurry obtained in step S2, stir at a speed of 200-250 r / min for 5-8 min, pour the resulting mixture into a mold, scrape the surface smooth, and obtain concrete material. S4. Place the concrete material obtained in step S3 on a vibration table and pass it through modes A, B and C respectively. After vibration, let it stand for 20-30 minutes, cover it with plastic film, place it at room temperature for 20-24 hours, then demold it and place it in a curing box for curing to obtain a gradient concrete slab based on waste incineration bottom ash. The preparation of modified emulsions includes the following steps: S21. By weight, add 0.05-0.1 parts of cellulose ether to 3-5 parts of deionized water and stir at 400-500 r / min for 10-15 min until the solution is transparent and viscous to obtain a preliminary mixture; S22. Add 1-2 parts of the modifying agent to the preliminary mixture and stir at 300-400 r / min for 10-15 min to obtain the secondary mixture; S23. Slowly add 12-16 parts of SBR emulsion to the mixture in the second step at a speed of 200-300 r / min. After the addition is complete, slowly add 0.1-0.3 parts of defoamer. Stir at a speed of 500-600 r / min for 5-10 min and let stand for 25-30 min to obtain the modified emulsion.

[0006] Preferably, the preparation of the modified curing agent includes the following steps: S11. By weight, add 1.5-2 parts calcium stearate, 0.1-0.3 parts polydimethylsiloxane and 0.5-1 parts calcium sulfate to a mixer and stir at 50-80 r / min for 5-10 min; S12. At a speed of 50-80 r / min, slowly add 3-5 parts of UEA low-alkali expansion agent and 1-2 parts of nano silica, and stir continuously for 20-30 min to obtain the modified curing agent.

[0007] Preferably, the preparation of the modified additive includes the following steps: S221. Dissolve 0.05-0.1 parts of sodium gluconate in 3-5 parts of deionized water by weight, and stir at 300-400 r / min for 5-10 min. S222. Add 0.1-0.3 parts of triethanolamine and 0.05-0.1 parts of alkylphenol polyoxyethylene ether to the solution obtained in step S221, and stir at a speed of 300-400 r / min for 3-5 min; S223. Adjust the stirring speed to 600-800 r / min, slowly add 0.5-1 part of film-forming aid, and complete the addition in 10-15 min. Then reduce the speed to 300-400 r / min and continue stirring for 8-10 min to finally obtain the modified aid.

[0008] Preferably, in step S4, the frequency of mode A is 47.7 Hz, the amplitude is 0.30 mm, and the time is 90 s; the frequency of mode B is 47.7 Hz, the amplitude is 0.45 mm, and the time is 120 s; and the frequency of mode C is 47.7 Hz, the amplitude is 0.60 mm, and the time is 150 s.

[0009] Preferably, in step S1, the cement is selected from ordinary Portland cement PO 42.5; the sand and gravel include river sand and crushed stone, wherein the fineness modulus of the river sand is 2.5-3.0, and the particle size of the crushed stone is 5-10mm; the particle size of the bottom ash from the waste incineration is ≤10mm.

[0010] Preferably, the water-reducing agent in step S2 is selected from polycarboxylate-based high-efficiency water-reducing agents with a solid content of 40%.

[0011] Preferably, the curing conditions in step S4 are a temperature of 18-22℃, a relative humidity of ≥95%, and a time of 25-28 days.

[0012] Preferably, the defoamer in step S23 is selected from BYK-028.

[0013] Preferably, the aggregate in step S1 consists of 80-100 parts cement, 8-10 parts silica fume, and 45-50 parts sand and gravel.

[0014] A gradient concrete slab based on waste incineration bottom ash is prepared according to the above preparation method.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention effectively slows down the cement hydration rate and improves the fluidity of the slurry through the synergistic effect of modified additives and modified emulsions, avoiding early workability loss caused by the high water absorption rate of bottom slag. It not only optimizes the rheological properties and workability of concrete, but also improves the microstructure by regulating the hydration process, reducing porosity and defects.

[0016] 2. This invention reduces drying shrinkage cracks caused by moisture migration through the synergistic effect of modified additives, modified emulsions and modified curing agents, compensates for the shrinkage stress of concrete, improves crack resistance, significantly improves the interface transition zone between the paste and the bottom slag aggregate, forming a dense-hydrophobic-micro-expansion composite system, effectively overcoming the durability shortcomings caused by the lightweight and porous bottom slag, and achieving simultaneous improvement in long-term stability and impermeability. Attached Figure Description

[0017] Figure 1 This is a process flow diagram of the preparation process of the gradient concrete slab based on waste incineration bottom ash of the present invention; Figure 2 This is a flow chart of the preparation process of the modified curing agent of the present invention; Figure 3 This is a process flow diagram for preparing the modified emulsion of the present invention; Figure 4 This is a flow chart of the preparation process of the modified additive of the present invention; Figure 5 This is a schematic diagram of the layered structure of concrete material after vibration in modes A, B, and C in step S4 of embodiment 1 of the present invention (block-shaped sample). Figure 6 This is a schematic diagram of the layered structure of concrete material after vibration in modes A, B, and C in step S4 of embodiment 2 of the present invention (block-shaped sample). Figure 7 This is a schematic diagram of the structural layers of the gradient concrete slab prepared according to the present invention. Detailed Implementation

[0018] The present invention will now be clearly and completely described in conjunction with embodiments thereof. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] Please see Figure 1-7 The present invention provides a technical solution: This invention induces stratification of concrete materials through three vibration modes, resulting in gradient concrete slabs based on waste incineration ash exhibiting enhanced mechanical properties. To better illustrate the stratification process, a cube-shaped sample was prepared, and the stratification details are shown in the attached figure. Figure 5-6 And drew an appendix Figure 7 A schematic diagram of the structural layers of a gradient concrete slab. The gradient concrete slab is roughly divided into two layers: the upper layer is a mixture of waste incineration bottom ash and polypropylene fibers, and the lower layer is a mixture of aggregates and steel fibers.

[0020] Example 1 A method for preparing gradient concrete slabs based on waste incineration bottom ash: Before preparing gradient concrete slabs based on waste incineration bottom ash, the following steps are taken: Modifying additives, modifying curing agents, and modifying emulsions are prepared: The preparation of the modifying agent includes the following steps: S221. Dissolve 0.05g sodium gluconate in 3ml deionized water and stir at 300r / min for 5min; S222. Add 0.1g of triethanolamine and 0.05g of alkylphenol polyoxyethylene ether to the solution obtained in step S221, and stir at 300r / min for 3min; S223. Adjust the stirring speed to 600 r / min, slowly add 0.5 g of Texanol ester alcohol, and finish adding it in 10 min. Then reduce the stirring speed to 300 r / min and continue stirring for 8 min to finally obtain the modified additive. The preparation of the modified curing agent includes the following steps: S11. Add 1.5g calcium stearate, 0.1g polydimethylsiloxane and 0.5g calcium sulfate to a mixer and stir at 50r / min for 5min; S12. At a speed of 50 r / min, slowly add 3g of UEA low-alkali expansion agent and 1g of nano silica in sequence, and stir continuously for 20 min to obtain the modified curing agent; The preparation of modified emulsions includes the following steps: S21. Add 0.05g of cellulose ether to 3ml of deionized water and stir at 400r / min for 10min until the solution is transparent and viscous to obtain a preliminary mixture; S22. Add 1g of modifying agent to the initial mixture and stir at 300r / min for 10min to obtain the second-step mixture; S23. Slowly add 12g of SBR emulsion to the mixture in this step at a speed of 200r / min. After the addition is complete, slowly add 0.1g of BYK-028. Stir at a speed of 500r / min for 5min and let stand for 25min to obtain the modified emulsion. S1. Place 80g of ordinary Portland cement (PO 42.5), 8g of silica fume, 45g of sand and gravel (including river sand and crushed stone, wherein the fineness modulus of the river sand is 2.5 and the particle size of the crushed stone is 5mm), 25g of waste incineration bottom ash (average particle size 5mm), and 5g of modified curing agent into a mixer and dry mix at a speed of 150r / min for 3min to obtain dry mix; S2. Mix 45ml of water, 1g of polycarboxylate superplasticizer with a solid content of 40% and 15g of modified emulsion evenly, and slowly add it to the dry mix. Stir at 150r / min for 5min until the slurry is uniform. S3. Add 0.3g of polypropylene fiber and 1.5g of steel fiber to the slurry obtained in step S2, stir at 200r / min for 5min, pour the resulting mixture into a 500mm×500mm×50mm mold, scrape the surface smooth, and obtain concrete material. S4. Place the concrete material obtained in step S3 on a vibration table and pass it through modes A, B, and C respectively (mode A: frequency 47.7Hz, amplitude 0.30mm, time 90s; mode B: frequency 47.7Hz, amplitude 0.45mm, time 120s; mode C: frequency 47.7Hz, amplitude 0.60mm, time 150s). After vibration, let it stand for 20 minutes, cover it with plastic film, place it at room temperature for 20 hours, then demold it and put it in a curing box (temperature 18℃, relative humidity 95%) for 25 days to obtain a gradient concrete slab based on waste incineration bottom ash.

[0021] Example 2 A method for preparing gradient concrete slabs based on waste incineration bottom ash: Before preparing gradient concrete slabs based on waste incineration bottom ash, the following steps are taken: Modifying additives, modifying curing agents, and modifying emulsions are prepared: The preparation of the modifying agent includes the following steps: S221. Dissolve 0.1g sodium gluconate in 5ml deionized water and stir at 400r / min for 10min; S222. Add 0.3g of triethanolamine and 0.1g of alkylphenol polyoxyethylene ether to the solution obtained in step S221, and stir at 400r / min for 5min; S223. Adjust the stirring speed to 800 r / min, slowly add 1g of Texanol ester alcohol, and finish adding it in 15 min. Then reduce the stirring speed to 400 r / min and continue stirring for 10 min to finally obtain the modified additive. The preparation of the modified curing agent includes the following steps: S11. Add 2g of calcium stearate, 0.3g of polydimethylsiloxane and 1g of calcium sulfate to a mixer and stir at 80r / min for 10min; S12. At a speed of 80 r / min, slowly add 5 g of UEA low-alkali expansion agent and 2 g of nano silica in sequence, and stir continuously for 30 min to obtain the modified curing agent; The preparation of modified emulsions includes the following steps: S21. Add 0.1g of cellulose ether to 5ml of deionized water and stir at 500r / min for 15min until the solution is transparent and viscous to obtain a preliminary mixture; S22. Add 2g of modifying agent to the initial mixture and stir at 400r / min for 15min to obtain the secondary mixture; S23. Slowly add 16g of SBR emulsion to the mixture in this step at a speed of 300r / min. After the addition is complete, slowly add 0.3g of BYK-028. Stir at a speed of 600r / min for 10min and let stand for 30min to obtain the modified emulsion. S1. Place 100g of ordinary Portland cement (PO 42.5), 10g of silica fume, 50g of sand and gravel (including river sand and crushed stone, wherein the fineness modulus of the river sand is 3.0 and the particle size of the crushed stone is 10mm), 30g of waste incineration bottom ash (average particle size 10mm), and 8g of modified curing agent into a mixer and dry mix at a speed of 200r / min for 5min to obtain dry mix; S2. Mix 50ml of water, 1.5g of polycarboxylate superplasticizer with a solid content of 40% and 20g of modified emulsion evenly, and slowly add it to the dry mix. Stir at 200r / min for 10min until the slurry is uniform. S3. Add 0.5g of polypropylene fiber and 2g of steel fiber to the slurry obtained in step S2, stir at 250r / min for 8min, pour the resulting mixture into a 500mm×500mm×50mm mold, scrape the surface smooth, and obtain concrete material. S4. Place the concrete material obtained in step S3 on a vibration table and pass it through modes A, B, and C respectively (mode A: frequency 47.7Hz, amplitude 0.30mm, time 90s; mode B: frequency 47.7Hz, amplitude 0.45mm, time 120s; mode C: frequency 47.7Hz, amplitude 0.60mm, time 150s). After vibration, let it stand for 30 minutes, cover it with plastic film, place it at room temperature for 24 hours, then demold it and place it in a curing box (temperature 22℃, relative humidity 98%) for 28 days to obtain a gradient concrete slab based on waste incineration bottom ash.

[0022] Example 3 A method for preparing gradient concrete slabs based on waste incineration bottom ash: Before preparing gradient concrete slabs based on waste incineration bottom ash, the following steps are taken: Modifying additives, modifying curing agents, and modifying emulsions are prepared: The preparation of the modifying agent includes the following steps: S221. Dissolve 0.06g sodium gluconate in 3.5ml deionized water and stir at 320r / min for 6min; S222. Add 0.15g of triethanolamine and 0.06g of alkylphenol polyoxyethylene ether to the solution obtained in step S221, and stir at 320r / min for 4min; S223. Adjust the stirring speed to 650 r / min, slowly add 0.6 g of Texanol ester alcohol, and add it completely in 11 min. Then reduce the stirring speed to 320 r / min and continue stirring for 9 min to finally obtain the modified additive. The preparation of the modified curing agent includes the following steps: S11. Add 1.6g calcium stearate, 0.15g polydimethylsiloxane and 0.6g calcium sulfate to a mixer and stir at 60r / min for 6min; S12. At a speed of 60 r / min, slowly add 3.5 g of UEA low-alkali expansion agent and 1.3 g of nano silica in sequence, and stir continuously for 22 min to obtain the modified curing agent; The preparation of modified emulsions includes the following steps: S21. Add 0.06g of cellulose ether to 3.5ml of deionized water and stir at 420r / min for 11min until the solution is transparent and viscous to obtain a preliminary mixture; S22. Add 1.2g of modifying agent to the initial mixture and stir at 320r / min for 11min to obtain the secondary mixture; S23. Slowly add 13g of SBR emulsion to the mixture in this step at a speed of 220r / min. After the addition is complete, slowly add 0.15g of BYK-028. Stir at a speed of 520r / min for 6min and let stand for 26min to obtain the modified emulsion. S1. Place 85g of ordinary Portland cement (PO 42.5), 8.5g of silica fume, 46g of sand and gravel (including river sand and crushed stone, wherein the fineness modulus of the river sand is 2.6 and the particle size of the crushed stone is 6mm), 26g of waste incineration bottom ash (particle size 6mm), and 6g of modified curing agent into a mixer and dry mix at a speed of 160r / min for 4min to obtain dry mix; S2. Mix 46ml of water, 1.1g of polycarboxylate superplasticizer with a solid content of 40% and 16g of modified emulsion evenly, and slowly add it to the dry mix. Stir at 160r / min for 6min until the slurry is uniform. S3. Add 0.35g of polypropylene fiber and 1.6g of steel fiber to the slurry obtained in step S2, stir at 220r / min for 6min, pour the resulting mixture into a 500mm×500mm×50mm mold, scrape the surface smooth, and obtain concrete material. S4. Place the concrete material obtained in step S3 on a vibration table and pass it through modes A, B, and C respectively (mode A: frequency 47.7Hz, amplitude 0.30mm, time 90s; mode B: frequency 47.7Hz, amplitude 0.45mm, time 120s; mode C: frequency 47.7Hz, amplitude 0.60mm, time 150s). After vibration, let it stand for 22 minutes, cover it with plastic film, place it at room temperature for 21 hours, then demold it and place it in a curing box (temperature 19℃, relative humidity 96%) for 26 days to obtain a gradient concrete slab based on waste incineration bottom ash.

[0023] Example 4 A method for preparing gradient concrete slabs based on waste incineration bottom ash: Before preparing gradient concrete slabs based on waste incineration bottom ash, the following steps are taken: Modifying additives, modifying curing agents, and modifying emulsions are prepared: The preparation of the modifying agent includes the following steps: S221. Dissolve 0.08g sodium gluconate in 4.2ml deionized water and stir at 340r / min for 8min; S222. Add 0.21g of triethanolamine and 0.08g of alkylphenol polyoxyethylene ether to the solution obtained in step S221, and stir at 360r / min for 4min; S223. Adjust the stirring speed to 720 r / min, slowly add 0.8 g of Texanol ester alcohol, and add it completely in 14 min. Then reduce the stirring speed to 370 r / min and continue stirring for 9 min to finally obtain the modified additive. The preparation of the modified curing agent includes the following steps: S11. Add 1.8g calcium stearate, 0.22g polydimethylsiloxane and 0.8g calcium sulfate to a mixer and stir at 75r / min for 8min; S12. At a speed of 75 r / min, slowly add 4.5 g of UEA low-alkali expansion agent and 1.8 g of nano silica in sequence, and stir continuously for 27 min to obtain the modified curing agent; The preparation of modified emulsions includes the following steps: S21. Add 0.08g of cellulose ether to 4ml of deionized water and stir at 480r / min for 14min until the solution is transparent and viscous to obtain a preliminary mixture; S22. Add 1.8g of modifying agent to the initial mixture and stir at 360r / min for 14min to obtain the secondary mixture; S23. Slowly add 15g of SBR emulsion to the mixture in this step at a speed of 270r / min. After the addition is complete, slowly add 0.25g of BYK-028. Stir at a speed of 580r / min for 9min and let stand for 29min to obtain the modified emulsion. S1. Place 93g of ordinary Portland cement (PO 42.5), 9.6g of silica fume, 49g of sand and gravel (including river sand and crushed stone, wherein the fineness modulus of the river sand is 2.8 and the particle size of the crushed stone is 9mm), 28g of waste incineration bottom ash (average particle size 9mm), and 7g of modified curing agent into a mixer and dry mix at 180r / min for 4min to obtain dry mix; S2. Mix 48ml of water, 1.4g of polycarboxylate superplasticizer with a solid content of 40% and 19g of modified emulsion evenly, and slowly add it to the dry mix. Stir at 180r / min for 9min until the slurry is uniform. S3. Add 0.41g of polypropylene fiber and 1.8g of steel fiber to the slurry obtained in step S2, stir at 240r / min for 7min, pour the resulting mixture into a 500mm×500mm×50mm mold, scrape the surface smooth, and obtain concrete material. S4. Place the concrete material obtained in step S3 on a vibration table and pass it through modes A, B, and C respectively (mode A: frequency 47.7Hz, amplitude 0.30mm, time 90s; mode B: frequency 47.7Hz, amplitude 0.45mm, time 120s; mode C: frequency 47.7Hz, amplitude 0.60mm, time 150s). After vibration, let it stand for 28 minutes, cover it with plastic film, place it at room temperature for 23 hours, then demold it and place it in a curing box (temperature 21℃, relative humidity 97%) for 27 days to obtain gradient concrete slabs based on waste incineration bottom ash.

[0024] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that no modified emulsion was added in this comparative example; the other steps are exactly the same in Comparative Example 1 and Example 1.

[0025] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that no modified curing agent was added in this comparative example; the other steps are exactly the same in Comparative Example 2 and Example 1.

[0026] Comparative Example 3 The only difference between Comparative Example 3 and Example 1 is that polypropylene fiber and steel fiber were not added in this comparative example, and vibration modes A, B, and C were not performed. The remaining steps are exactly the same in Comparative Example 3 and Example 1.

[0027] Comparative Example 4 The only difference between Comparative Example 4 and Example 1 is that vibration modes A, B, and C were not performed in this comparative example. All other steps are exactly the same in Comparative Example 4 and Example 1.

[0028] Performance testing: According to GB / T 50080 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", the slump of the gradient concrete slabs based on waste incineration bottom ash obtained in Examples 1-4 and Comparative Examples 1-2 were tested using a slump cone. According to GB / T 50081 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", the compressive strength of the gradient concrete slabs based on waste incineration bottom ash obtained in Examples 1-4 and Comparative Examples 1-2 was tested using a pressure testing machine at a rate of 0.5 MPa / s until failure. According to GB / T 50082 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete", the length change of the gradient concrete slabs based on waste incineration bottom ash obtained in Examples 1-4 and Comparative Examples 1-2 at different ages was measured using a length comparator, and the drying shrinkage was tested. The gradient concrete slabs based on waste incineration bottom ash obtained in Examples 1-4 and Comparative Examples 1-2 were soaked in a saturated surface-dry state for 24 hours, and the mass before and after water absorption was measured to test the water absorption rate. The relevant data are shown in Table 1 below. Table 1

[0029] The gradient concrete slabs based on waste incineration ash obtained in Examples 1-4 showed significantly higher slump than those obtained in Comparative Examples 1-2, indicating that the synergistic effect of the modified emulsion and modified curing agent effectively mitigated the workability loss caused by the high water absorption of the ash. The gradient concrete slabs based on waste incineration ash obtained in Examples 1-4 exhibited superior mechanical properties, crack resistance, and durability compared to Comparative Examples 1-2. This is because the UEA expansive agent and nano-silica in the modified curing agent effectively inhibited shrinkage, and their synergistic effect with the modified emulsion and modified additives effectively compensated for the low strength of the ash. Furthermore, the excellent water absorption rate demonstrates that the synergistic effect of these three components effectively achieved hydrophobic treatment.

[0030] To better verify the effects of polypropylene fiber, steel fiber, and vibration stratification on the performance of the resulting gradient concrete slab based on waste incineration bottom ash in this invention, comparative examples 3 and 4 were set up to compare the performance with Example 1 of this invention. The final data are shown in Table 2 below: Table 2

[0031] As can be seen from the data in Table 2, the gradient concrete slab based on waste incineration bottom ash obtained in Example 1 of the present invention has significantly better performance than Comparative Examples 3-4, proving that vibration stratification and both types of fibers can effectively improve the performance of the slab.

[0032] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing gradient concrete slabs based on waste incineration bottom ash, characterized in that, The preparation steps include the following: S1. By weight, put 25-30 parts of waste incineration bottom ash, 5-8 parts of modified curing agent and 133-160 parts of aggregate into a mixer and dry mix at a speed of 150-200 r / min for 3-5 minutes to obtain dry mix. S2. Mix 45-50 parts water, 1-1.5 parts water-reducing agent and 15-20 parts modified emulsion evenly, slowly add to dry mix, and stir at 150-200 r / min for 5-10 min until the slurry is uniform. S3. Add 0.3-0.5 parts of polypropylene fiber and 1.5-2 parts of steel fiber to the slurry obtained in step S2, stir at a speed of 200-250 r / min for 5-8 min, pour the resulting mixture into a mold, scrape the surface smooth, and obtain concrete material. S4. Place the concrete material obtained in step S3 on a vibration table and pass it through modes A, B and C respectively. After vibration, let it stand for 20-30 minutes, cover it with plastic film, place it at room temperature for 20-24 hours, then demold it and place it in a curing box for curing to obtain a gradient concrete slab based on waste incineration bottom ash. The preparation of the modified emulsion includes the following steps: S21. By weight, add 0.05-0.1 parts of cellulose ether to 3-5 parts of deionized water and stir at 400-500 r / min for 10-15 min until the solution is transparent and viscous to obtain a preliminary mixture; S22. Add 1-2 parts of the modifying agent to the preliminary mixture and stir at 300-400 r / min for 10-15 min to obtain the secondary mixture; S23. Slowly add 12-16 parts of SBR emulsion to the mixture in the second step at a speed of 200-300 r / min. After the addition is complete, slowly add 0.1-0.3 parts of defoamer. Stir at a speed of 500-600 r / min for 5-10 min and let stand for 25-30 min to obtain the modified emulsion.

2. The method for preparing a gradient concrete slab based on waste incineration bottom ash according to claim 1, characterized in that, The preparation of the modified curing agent includes the following steps: S11. By weight, add 1.5-2 parts calcium stearate, 0.1-0.3 parts polydimethylsiloxane and 0.5-1 parts calcium sulfate to a mixer and stir at 50-80 r / min for 5-10 min; S12. At a speed of 50-80 r / min, slowly add 3-5 parts of UEA low-alkali expansion agent and 1-2 parts of nano silica, and stir continuously for 20-30 min to obtain the modified curing agent.

3. The method for preparing a gradient concrete slab based on waste incineration bottom ash according to claim 1, characterized in that, The preparation of the modified additive includes the following steps: S221. Dissolve 0.05-0.1 parts of sodium gluconate in 3-5 parts of deionized water by weight, and stir at 300-400 r / min for 5-10 min. S222. Add 0.1-0.3 parts of triethanolamine and 0.05-0.1 parts of alkylphenol polyoxyethylene ether to the solution obtained in step S221, and stir at a speed of 300-400 r / min for 3-5 min; S223. Adjust the stirring speed to 600-800 r / min, slowly add 0.5-1 part of film-forming aid, and complete the addition in 10-15 min. Then reduce the speed to 300-400 r / min and continue stirring for 8-10 min to finally obtain the modified aid.

4. The method for preparing a gradient concrete slab based on waste incineration bottom ash according to claim 1, characterized in that, In step S4, the frequency of mode A is 47.7 Hz, the amplitude is 0.30 mm, and the time is 90 s; the frequency of mode B is 47.7 Hz, the amplitude is 0.45 mm, and the time is 120 s; and the frequency of mode C is 47.7 Hz, the amplitude is 0.60 mm, and the time is 150 s.

5. The method for preparing a gradient concrete slab based on waste incineration bottom ash according to claim 1, characterized in that, The cement mentioned in step S1 is selected from ordinary Portland cement PO 42.5; the sand and gravel include river sand and crushed stone, wherein the fineness modulus of the river sand is 2.5-3.0, and the particle size of the crushed stone is 5-10mm; the particle size of the bottom ash of the waste incineration is ≤10mm.

6. The method for preparing a gradient concrete slab based on waste incineration bottom ash according to claim 1, characterized in that, The water-reducing agent mentioned in step S2 is selected from polycarboxylate-based high-efficiency water-reducing agents with a solid content of 40%.

7. The method for preparing a gradient concrete slab based on waste incineration bottom ash according to claim 1, characterized in that, The curing conditions in step S4 are a temperature of 18-22℃, a relative humidity of ≥95%, and a time of 25-28 days.

8. The method for preparing a gradient concrete slab based on waste incineration bottom ash according to claim 1, characterized in that, In step S23, the defoamer is selected from BYK-028.

9. The method for preparing a gradient concrete slab based on waste incineration bottom ash according to claim 1, characterized in that, The aggregate in step S1 consists of 80-100 parts cement, 8-10 parts silica fume, and 45-50 parts sand and gravel.

10. A gradient concrete slab based on waste incineration bottom ash, characterized in that, It is prepared according to the preparation method described in any one of claims 1-9 above.

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