A full-solid waste carbon-reducing and toughness-increasing concrete and a preparation method thereof

Abstract

The present application relates to the technical field of concrete preparation, and particularly relates to a full-solid-waste carbon-reducing and toughness-increasing concrete and a preparation method thereof.The full-solid-waste carbon-reducing and toughness-increasing concrete comprises the following components by mass fraction: coal gangue 520-710 parts, fly ash 160-240 parts, slag 220-280 parts, modified montmorillonite 28-46 parts, deionized water 240-320 parts, and water reducing agent 8-18 parts.The montmorillonite provided by the present application is easy to peel off between layers and enters the concrete slurry, thereby improving the promoting effect of the montmorillonite on the strength of the concrete.In the present application, the montmorillonite is loaded with nano calcium carbonate, the nano calcium carbonate provides more nucleation sites, and further improves the strength of the concrete;meanwhile, the nano calcium carbonate enters the concrete slurry along with the easy-to-peel-off montmorillonite and is easy to disperse.

Description

Technical Field

[0001] This invention relates to the field of concrete preparation technology, specifically to a carbon-reduced and toughened all-solid-waste concrete and its preparation method. Background Technology

[0002] Cement is a crucial raw material in concrete, but its production process generates significant carbon emissions, which contradicts the requirements for energy conservation and a green environment. my country, however, has a large stockpile of solid waste, including coal gangue, fly ash, and slag. These solid wastes can be utilized in concrete preparation, improving resource utilization and playing a vital role in conserving resources and promoting the green and high-quality development of the concrete industry.

[0003] When preparing concrete using solid waste, various additives are used to improve concrete performance. Montmorillonite is one such additive that can enhance concrete properties, such as strength, durability, and shrinkage. However, existing montmorillonite is typically added directly to concrete materials. This often results in layers of montmorillonite being difficult to separate, leading to a buildup of montmorillonite, reduced dispersibility, and decreased specific surface area, thus limiting its performance improvement. Therefore, to address the problems mentioned in the background, those skilled in the art have modified montmorillonite to facilitate layer separation. Furthermore, the separated montmorillonite can disperse its loaded nano-calcium carbonate into the concrete slurry. The nucleation effect of the nano-calcium carbonate further improves the concrete's performance. Summary of the Invention

[0004] The purpose of this invention is to provide a carbon-reduced and toughened concrete made entirely from solid waste and its preparation method, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A carbon-reducing and toughening concrete made entirely from solid waste comprises the following components by weight: 520-710 parts coal gangue, 160-240 parts fly ash, 220-280 parts slag, 28-46 parts modified montmorillonite, 240-320 parts deionized water, and 8-18 parts water-reducing agent.

[0007] The preparation method of the modified montmorillonite includes the following steps:

[0008] S101. Disperse montmorillonite in deionized water, heat to 60-70℃ and stir for 0.5-2 hours to prepare a montmorillonite suspension;

[0009] S102. Add calcium chloride solution to the montmorillonite suspension obtained in step S101, heat to 70-80℃, and react continuously for 2-3 hours to obtain a reaction solution.

[0010] S103. After the reaction solution in step S102 is cooled to room temperature, sodium carbonate solution is added and the reaction is continued for 1-2 hours. Then, the product is filtered, washed with sufficient deionized water, and vacuum dried at 60-100℃ to constant weight to obtain the dried product.

[0011] S104. The dried material obtained in step S103 is placed in a tube furnace and calcined at 170-220°C for 1-4 hours under a nitrogen atmosphere to obtain the heated material.

[0012] S105. Add liquid nitrogen to the heated material obtained in step S104 until the liquid nitrogen is vaporized. The heated material is treated with liquid nitrogen to obtain modified montmorillonite.

[0013] Furthermore, in step S101, the mass ratio between montmorillonite and deionized water is 1:(80-150).

[0014] Furthermore, the mass ratio between the calcium chloride solution used in step S102 and the deionized water used in step S101 is 1:(4-6), and the concentration of the calcium chloride solution is 3-5wt%.

[0015] Furthermore, the mass ratio between the sodium carbonate solution used in step S103 and the deionized water used in step S101 is 1:(3-4), and the concentration of the sodium carbonate solution is 3-5 wt%.

[0016] Furthermore, the heated material in step S105 is treated with liquid nitrogen a total of 2-4 times, with the amount of liquid nitrogen added each time being 5-10 times the mass of the montmorillonite used in step S101.

[0017] A method for preparing carbon-reduced and toughened concrete made entirely from solid waste, the method comprising the following steps:

[0018] S1. According to the mass fraction, coal gangue, fly ash and slag are put into a muffle furnace and calcined at 900-1200℃ for 2-4 hours to obtain a mixture;

[0019] S2. After the mixture in step S1 has cooled to room temperature, add deionized water, water-reducing agent and modified montmorillonite in sequence according to the mass fraction, stir and mix evenly to obtain concrete slurry.

[0020] S3. Pour the slurry obtained in step S2 into the mold, cure and demold to obtain all-solid-waste carbon-reduced and toughened concrete.

[0021] Furthermore, the water-reducing agent added in step S2 is a polycarboxylate water-reducing agent.

[0022] Furthermore, in step S2, the stirring speed is 100-200 rpm and the stirring time is 0.5-1.5 h.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. In this invention, coal gangue, fly ash and slag are used as the basic materials for concrete, which effectively saves resources, reduces carbon emissions and is beneficial to the environment. At the same time, montmorillonite is added to the prepared concrete, which can effectively enhance the strength and toughness of the concrete.

[0025] 2. The montmorillonite added in this invention is modified montmorillonite. The modified montmorillonite in this invention utilizes the interlayer exchange effect of montmorillonite to load nano-calcium carbonate into the interlayer of montmorillonite. The nano-calcium carbonate enters the concrete, providing more nucleation sites and further improving the strength of the concrete. In addition, the montmorillonite in this invention is treated with liquid nitrogen, making it easy to peel off. During the mixing and hydration process, the montmorillonite is easily peeled off, and the loaded nano-calcium carbonate is uniformly mixed into the concrete. Furthermore, the non-stacking montmorillonite has a further effect on improving the strength of the concrete. Attached Figure Description

[0026] Figure 1 This is a process flow diagram for preparing carbon-reduced and toughened concrete from all solid waste according to the present invention.

[0027] Figure 2 This is a process flow diagram for preparing modified montmorillonite in this invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Please see Figures 1 to 2 The present invention provides:

[0030] Example 1

[0031] A method for preparing carbon-reduced and toughened concrete made entirely from solid waste, the method comprising the following steps:

[0032] S1. Put 620g of coal gangue, 205g of fly ash and 240g of slag into a muffle furnace and calcine at 1100℃ for 3 hours to obtain a mixture;

[0033] S2. After the mixture in step S1 has cooled to room temperature, add 41g of modified montmorillonite, 300g of deionized water and 11g of water-reducing agent to it, and stir and mix at 120rpm for 1.2h to obtain concrete slurry.

[0034] S3. Pour the slurry obtained in step S2 into the mold, cure and demold to obtain all-solid-waste carbon-reduced and toughened concrete.

[0035] The preparation method of the above-mentioned modified montmorillonite includes the following steps:

[0036] S101. Disperse 50g of montmorillonite in 4500g of deionized water, heat to 65℃ and stir for 1.2h to prepare a montmorillonite suspension.

[0037] S102. Add 900g of 4wt% calcium chloride solution to the montmorillonite suspension obtained in step S101, heat to 75℃, and react continuously for 2.5h to obtain the reaction solution.

[0038] S103. After the reaction solution in step S102 has cooled to room temperature, add 1280g of sodium carbonate solution with a concentration of 4wt% and react continuously for 1.2h. Then filter, wash the filtered product with sufficient deionized water and dry it under vacuum at 90℃ to constant weight to obtain the dried product.

[0039] S104. The dried material obtained in step S103 is placed in a tube furnace and calcined at 180°C for 3 hours under a nitrogen atmosphere to obtain the heated material.

[0040] S105. Add liquid nitrogen to the heated material obtained in step S104 until the liquid nitrogen is vaporized. The heated material is treated with liquid nitrogen to obtain modified montmorillonite.

[0041] In step S105, the heated material was treated with liquid nitrogen a total of 3 times, with 300g of liquid nitrogen added each time.

[0042] Example 2

[0043] A method for preparing carbon-reduced and toughened concrete made entirely from solid waste, the method comprising the following steps:

[0044] S1. Put 520g of coal gangue, 160g of fly ash and 220g of slag into a muffle furnace and calcine at 900℃ for 2 hours to obtain a mixture;

[0045] S2. After the mixture in step S1 has cooled to room temperature, add 28g of modified montmorillonite, 240g of deionized water and 8g of water-reducing agent, and stir at 100rpm for 0.5h to obtain concrete slurry.

[0046] S3. Pour the slurry obtained in step S2 into the mold, cure and demold to obtain all-solid-waste carbon-reduced and toughened concrete.

[0047] The preparation method of the above-mentioned modified montmorillonite includes the following steps:

[0048] S101. Disperse 50g of montmorillonite in 4000g of deionized water, heat to 60℃ and stir for 0.5h to prepare a montmorillonite suspension.

[0049] S102. Add 1000g of calcium chloride solution with a concentration of 3wt% to the montmorillonite suspension obtained in step S101, heat to 70℃, and react continuously for 2 hours to obtain the reaction solution.

[0050] S103. After the reaction solution in step S102 has cooled to room temperature, add 1333g of sodium carbonate solution with a concentration of 3wt% and react continuously for 1 hour. Then filter, wash the filtered product with sufficient deionized water and dry it under vacuum at 60°C to constant weight to obtain the dried product.

[0051] S104. The dried material obtained in step S103 is placed in a tube furnace and calcined at 170°C for 1 hour under a nitrogen atmosphere to obtain the heated material.

[0052] S105. Add liquid nitrogen to the heated material obtained in step S104 until the liquid nitrogen is vaporized. The heated material is treated with liquid nitrogen to obtain modified montmorillonite.

[0053] In step S105, the heated material was treated with liquid nitrogen twice, with 250g of liquid nitrogen added each time.

[0054] Example 3

[0055] A method for preparing carbon-reduced and toughened concrete made entirely from solid waste, the method comprising the following steps:

[0056] S1. Put 710g of coal gangue, 240g of fly ash and 280g of slag into a muffle furnace and calcine at 1200℃ for 4 hours to obtain a mixture;

[0057] S2. After the mixture in step S1 has cooled to room temperature, add 46g of modified montmorillonite, 320g of deionized water and 8-18g of water-reducing agent, and stir at 200rpm for 1.5h to obtain concrete slurry.

[0058] S3. Pour the slurry obtained in step S2 into the mold, cure and demold to obtain all-solid-waste carbon-reduced and toughened concrete.

[0059] The preparation method of the above-mentioned modified montmorillonite includes the following steps:

[0060] S101. Disperse 50g of montmorillonite in 7500g of deionized water, heat to 70℃ and stir for 2h to prepare a montmorillonite suspension.

[0061] S102. Add 1250g of 5wt% calcium chloride solution to the montmorillonite suspension obtained in step S101, heat to 80℃, and react continuously for 3 hours to obtain the reaction solution.

[0062] S103. After the reaction solution in step S102 is cooled to room temperature, 1875g of sodium carbonate solution with a concentration of 5wt% is added, and the reaction is carried out continuously for 2 hours. After that, the product is filtered, washed with sufficient deionized water, and dried under vacuum at 100°C to constant weight to obtain the dried product.

[0063] S104. The dried material obtained in step S103 is placed in a tube furnace and calcined at 220°C for 4 hours under a nitrogen atmosphere to obtain the heated material.

[0064] S105. Add liquid nitrogen to the heated material obtained in step S104 until the liquid nitrogen is vaporized. The heated material is treated with liquid nitrogen to obtain modified montmorillonite.

[0065] In step S105, the heated material was treated with liquid nitrogen a total of 4 times, with 500g of liquid nitrogen added each time.

[0066] Example 4

[0067] A method for preparing carbon-reduced and toughened concrete made entirely from solid waste, the method comprising the following steps:

[0068] S1. Put 680g of coal gangue, 210g of fly ash and 250g of slag into a muffle furnace and calcine at 1100℃ for 3 hours to obtain a mixture;

[0069] S2. After the mixture in step S1 has cooled to room temperature, add 35g of modified montmorillonite, 280g of deionized water and 16g of water-reducing agent to it, and stir and mix at 150rpm for 1.2h to obtain concrete slurry.

[0070] S3. Pour the slurry obtained in step S2 into the mold, cure and demold to obtain all-solid-waste carbon-reduced and toughened concrete.

[0071] The preparation method of the above-mentioned modified montmorillonite includes the following steps:

[0072] S101. Disperse 50g of montmorillonite in 5000g of deionized water, heat to 65℃ and stir for 1.5h to prepare a montmorillonite suspension.

[0073] S102. Add 1000g of calcium chloride solution with a concentration of 4wt% to the montmorillonite suspension obtained in step S101, heat to 70℃, and react continuously for 2-3 hours to obtain the reaction solution.

[0074] S103. After the reaction solution in step S102 has cooled to room temperature, add 1200g of sodium carbonate solution with a concentration of 4wt% and react continuously for 2 hours. Then filter, wash the filtered product with sufficient deionized water and dry it under vacuum at 90°C to constant weight to obtain the dried product.

[0075] S104. The dried material obtained in step S103 is placed in a tube furnace and calcined at 200°C for 3 hours under a nitrogen atmosphere to obtain the heated material.

[0076] S105. Add liquid nitrogen to the heated material obtained in step S104 until the liquid nitrogen is vaporized. The heated material is treated with liquid nitrogen to obtain modified montmorillonite.

[0077] In step S105, the heated material was treated with liquid nitrogen a total of 3 times, with 350g of liquid nitrogen added each time.

[0078] Comparative Example 1

[0079] The difference between Comparative Example 1 and Example 1 is that steps S102 and S103 are omitted, while the remaining steps are exactly the same as in Example 1.

[0080] Comparative Example 2

[0081] The difference between Comparative Example 2 and Example 1 is that step S105 is omitted, while the remaining steps are exactly the same as in Example 1.

[0082] Comparative Example 3

[0083] The difference between Comparative Example 3 and Example 1 is that the addition of modified montmorillonite in step S2 was completely omitted, while the remaining steps are exactly the same as in Example 1.

[0084] In the above embodiments, the water-reducing agent is a polycarboxylate water-reducing agent;

[0085] The coal gangue used in this invention has a particle size of 10-20 mm, fly ash has a particle size of 200-300 μm, slag has a particle size of 1-5 mm, and montmorillonite has a particle size of 100-200 μm.

[0086] In step S3 of the above implementation method, the curing time is 7 days, the curing temperature is 80℃, and the relative humidity is 95%.

[0087] A total of seven groups of concrete were prepared through Examples 1-4 and Comparative Examples 1-3. Performance tests were conducted on these seven groups of concrete according to the GB-T 50081-2019 standard for testing the physical and mechanical properties of concrete. The performance test results are shown in Table 1 below.

[0088] Table 1: Performance test results of 7 groups of concrete prepared in Examples 1-4 and Comparative Examples 1-3

[0089]

[0090] As can be seen from the data in Table 1 above, the compressive strength and flexural strength of Comparative Example 1 are lower than those of Example 1. Comparative Example 1 lacks the interlayer synthesis process of nano-calcium carbonate in montmorillonite, thus lacking the nucleation effect of nano-calcium carbonate in concrete, which reduces the performance of concrete. Comparative Example 2 lacks the liquid nitrogen treatment of montmorillonite compared to Comparative Example 1. The interlayers of montmorillonite in Comparative Example 2 are more compact than those in Example 1. During the subsequent hydration and mixing process, the interlayers of montmorillonite are not easily separated, which leads to easy stacking of montmorillonite and also hinders the uniform dispersion of nano-calcium carbonate in the concrete as the interlayers of montmorillonite are separated, thus reducing the overall mechanical properties of the concrete.

[0091] 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 carbon-reducing and toughening concrete made entirely from solid waste, characterized in that, Materials comprising the following components by weight: 520-710 parts coal gangue, 160-240 parts fly ash, 220-280 parts slag, 28-46 parts modified montmorillonite, 240-320 parts deionized water, and 8-18 parts water-reducing agent. The preparation method of the modified montmorillonite includes the following steps: S101. Disperse montmorillonite in deionized water, heat to 60-70℃ and stir for 0.5-2 hours to prepare a montmorillonite suspension; S102. Add calcium chloride solution to the montmorillonite suspension obtained in step S101, heat to 70-80℃, and react continuously for 2-3 hours to obtain a reaction solution. S103. After the reaction solution in step S102 is cooled to room temperature, sodium carbonate solution is added and the reaction is continued for 1-2 hours. Then, the product is filtered, washed with sufficient deionized water, and vacuum dried at 60-100℃ to constant weight to obtain the dried product. S104. The dried material obtained in step S103 is placed in a tube furnace and calcined at 170-220°C for 1-4 hours under a nitrogen atmosphere to obtain the heated material. S105. Add liquid nitrogen to the heated material obtained in step S104 until the liquid nitrogen is vaporized. The heated material is treated with liquid nitrogen to obtain modified montmorillonite.

2. The all-solid-waste carbon-reduced and toughened concrete according to claim 1, characterized in that, In step S101, the mass ratio of montmorillonite to deionized water is 1:(80-150).

3. The all-solid-waste carbon-reducing and toughened concrete according to claim 1, characterized in that, The mass ratio of the calcium chloride solution used in step S102 to the deionized water used in step S101 is 1:(4-6), and the concentration of the calcium chloride solution is 3-5wt%.

4. The all-solid-waste carbon-reduced and toughened concrete according to claim 1, characterized in that, The mass ratio between the sodium carbonate solution used in step S103 and the deionized water used in step S101 is 1:(3-4), and the concentration of the sodium carbonate solution is 3-5wt%.

5. The all-solid-waste carbon-reducing and toughened concrete according to claim 1, characterized in that, The heated material in step S105 is treated with liquid nitrogen a total of 2-4 times, and the amount of liquid nitrogen added each time is 5-10 times the mass of the montmorillonite used in step S101.

6. The method for preparing all-solid-waste carbon-reduced and toughened concrete according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: S1. According to the mass fraction, coal gangue, fly ash and slag are put into a muffle furnace and calcined at 900-1200℃ for 2-4 hours to obtain a mixture; S2. After the mixture in step S1 has cooled to room temperature, add deionized water, water-reducing agent and modified montmorillonite in sequence according to the mass fraction, stir and mix evenly to obtain concrete slurry. S3. Pour the slurry obtained in step S2 into the mold, cure and demold to obtain all-solid-waste carbon-reduced and toughened concrete.

7. The method for preparing all-solid-waste carbon-reduced and toughened concrete according to claim 6, characterized in that, The water-reducing agent added in step S2 is a polycarboxylate water-reducing agent.

8. The method for preparing all-solid-waste carbon-reduced and toughened concrete according to claim 6, characterized in that, In step S2, the stirring speed is 100-200 rpm and the stirring time is 0.5-1.5 h.

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