Ecological concrete based on solid waste recycling

Abstract

The invention relates to the technical field of ecological concrete, in particular to ecological concrete based on solid waste recycling, and the ecological concrete based on solid waste recycling is prepared from the following raw materials in parts by weight: 20-26 parts of Portland cement; 22-29 parts of solid waste aggregate; 8-20 parts of an interface regulation and control component; 11 to 17 parts of water; wherein the surface of the solid waste aggregate is coated with an active solid waste micro-powder layer, and the thickness of the coating layer is 10-100 [mu] m. The surface of the solid waste aggregate is coated with steel slag micro-powder, C-S-H gel is generated in situ in an interface area, the bonding strength reaches 8.7 MPa, the problem of interface stripping is thoroughly solved, and the adsorption rate is greatly increased by constructing micro-channels in the interface area by calcining zeolite through coal gangue; the acidic red mud neutralizes the alkaline percolate and maintains a microbial friendly environment with the pH value of 7.5-8.5, and meanwhile, the coating layer on the surface of the porous aggregate increases microbial attachment sites and couples an ion adsorption function, so that the TN and TP removal efficiency is improved by 12-15% compared with the original patent.

Description

Technical Field

[0001] The present invention relates to the technical field of ecological concrete, and in particular to an ecological concrete based on solid waste recycling. Background Art

[0002] Ecological concrete, cast-in-place vegetation-type ecological concrete (large aggregate sandless concrete) is a new type of ecological concrete slope protection technology used for the management and protection of water conservancy project slopes (such as waterfront areas, rivers, dams, reservoirs, reservoirs, etc.), and takes environmental factors into consideration. It is a mixture of coarse aggregates of continuous particle sizes and a certain amount of fine aggregates in a certain proportion range (fine aggregates can be omitted if necessary), and then stirred. After pouring and natural curing, a porous concrete with a surface resembling rice candy and a large number of interconnected, fine pores can be obtained. Its biggest feature is the presence of a large number of individual or continuous pores, and it has multiple functions that ordinary concrete and ordinary ecological concrete do not have. Therefore, this concrete has received widespread attention and has huge potential application value not only in the field of concrete, but also in many fields such as ecology and environmental protection.

[0003] However, the solid waste aggregates used in existing technologies, such as expanded clay, have smooth surfaces and low activity, and their bonding strength with cement is insufficient, usually ≤5MPa, which leads to interfacial spalling and deterioration of durability of concrete under salt-freeze erosion. In addition, existing technologies rely on chemical additives (such as water reducers and activators) to improve interfacial properties, but this will raise the pH value, inhibit microbial attachment, and cannot actively adsorb pollutants. In view of this, we propose an ecological concrete based on solid waste recycling. Summary of the Invention

[0004] The purpose of the present invention is to solve the deficiencies mentioned in the above background technology and provide an ecological concrete based on solid waste recycling.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: An ecological concrete based on solid waste recycling, the ecological concrete based on solid waste recycling is composed of the following raw materials in parts by weight: Portland cement: 20-26 parts; Solid waste aggregate: 22-29 parts; Interface control component: 8-20 parts; Water: 11-17 parts; The surface of the solid waste aggregate is coated with an active solid waste powder layer, and the coating layer has a thickness of 10-100 μm; The interface regulating component is composed of pH regulating solid waste and ion adsorption solid waste in a mass ratio of (2-4):1.

[0006] Preferably, the active solid waste powder is at least one of fly ash, steel slag powder and metakaolin solid waste.

[0007] Preferably, the pH-regulated solid waste is at least one of steel slag powder, carbide slag, tailings powder and red mud.

[0008] Preferably, the ion-adsorption solid waste is at least one of zeolite solid waste, activated carbon-derived solid waste and modified red mud.

[0009] Preferably, the coating amount of the active solid waste fine powder layer is 5-12% of the mass of the solid waste aggregate.

[0010] Preferably, the zeolitic solid waste is at least one of natural zeolite and coal gangue calcined zeolite.

[0011] Preferably, the solid waste aggregate is ceramsite made by sintering 19-25 parts of steel slag powder, 15-21 parts of phosphorus slag powder, 27-34 parts of plant fiber and 20-29 parts of sludge powder at 900-1200°C.

[0012] A method for preparing ecological concrete based on solid waste recycling comprises the following steps: Step 1: mixing solid waste aggregate and active solid waste fine powder in a mass ratio of 100:(5-12) by weight, and subjecting the mixture to a mechanochemical treatment for 20-60 minutes to form a coating layer to obtain a pretreated aggregate; Step 2: Dry mix the Portland cement and interface control components for 60 seconds, then add water and pretreated aggregate to form a slurry; Step 3: Standard curing after slurry casting.

[0013] Preferably, the rotation speed of the mechanochemical treatment in step 1 is 300-500 r / min.

[0014] Preferably, the stirring time in step 2 is 120-180s.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention coats the surface of solid waste aggregate with steel slag powder, generates CSH gel in situ in the interface area, increases the bonding strength to 8.7 MPa, and completely solves the interface peeling problem.

[0016] The present invention constructs micro-channels in the interface area by calcining zeolite with coal gangue, which greatly improves the The adsorption rate is improved, and the acidic red mud neutralizes the alkaline leachate to maintain a microbial-friendly environment with a pH of 7.5-8.5. At the same time, the porous aggregate surface coating increases the microbial attachment sites and couples the ion adsorption function to increase the TN and TP removal efficiency by 12-15% compared with the original patent.

[0017] The present invention abandons artificial synthetic materials such as polycarboxylic acid water reducers and rust inhibitors, and only achieves self-reinforcement through matching of solid waste components (such as the alkalinity of steel slag powder to stimulate the activity of red mud), reducing carbon emissions by 18-22%. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0019] The present invention describes the above technical solution in detail through the following embodiments: Example 1 An ecological concrete based on solid waste recycling, the ecological concrete based on solid waste recycling is composed of the following raw materials in parts by weight: Portland cement: 23 parts; Solid waste aggregate: 22 parts; Interface control component: 8 parts; Water: 15 parts; The surface of the solid waste aggregate is coated with an active solid waste microlayer, the coating thickness is 80 μm, and the coating amount of the active solid waste microlayer is 12% of the mass of the solid waste aggregate; Among them, the interface control component is composed of steel slag powder and coal gangue calcined zeolite in a mass ratio of 2:1.

[0020] Among them, the solid waste aggregate is ceramsite made by sintering 23 parts of steel slag powder, 18 parts of phosphorus slag powder, 30 parts of rice straw and 29 parts of sludge powder at 1100℃. The surface roughness of the solid waste aggregate is Ra≥3.2μm, or it is pre-attached fine solid waste particles with a particle size of 0.01-0.1mm; the fine solid waste particles are at least one of steel slag sand, waste glass powder, and broken ceramic powder, and the attachment amount is 8% of the aggregate mass. The fine solid waste particles are attached to the surface of the solid waste aggregate through mechanical and chemical effects. The processing equipment is a ball mill or a high-speed mixer, and the ball-to-material ratio is 5:1.

[0021] A method for preparing ecological concrete based on solid waste recycling comprises the following steps: Step 1: Mix ceramsite and steel slag powder in a mass ratio of 100:8 by weight, subject them to mechanochemical treatment for 20-60 minutes to form a coating layer, and attach waste glass powder at a rotation speed of 500 r / min to obtain pretreated aggregate; Step 2: Dry mix the Portland cement and interface control components for 60 seconds, then add water and pretreated aggregate and stir for 120 seconds to form a slurry; Step 3: Standard curing after slurry casting.

[0022] Example 2 The only difference between this embodiment and embodiment 1 is that: in this embodiment, there are 23 parts of Portland cement, 25 parts of solid waste aggregate, 13 parts of interface control component and 15 parts of water, and other conditions are the same.

[0023] Example 3 The only difference between this embodiment and embodiment 1 is that: in this embodiment, there are 23 parts of Portland cement, 27 parts of solid waste aggregate, 16 parts of interface control component and 15 parts of water, and other conditions are the same.

[0024] Example 4 The only difference between this embodiment and embodiment 1 is that: in this embodiment, there are 23 parts of Portland cement, 29 parts of solid waste aggregate, 20 parts of interface control component and 15 parts of water, and other conditions are the same.

[0025] Example 5 The only difference between this embodiment and embodiment 1 is that the interface control component in this embodiment is composed of steel slag powder and coal gangue calcined zeolite in a mass ratio of 4:1, and other conditions are the same.

[0026] Comparative Example 1 The only difference between this comparative example and Example 1 is that the surface of the solid waste aggregate in this comparative example is not coated with an active solid waste microlayer, and other conditions are the same.

[0027] Comparative Example 2 The only difference between this comparative example and Example 1 is that no interface regulating component is added in this comparative example, and other conditions are the same.

[0028] Comparative Example 3 The only difference between this comparative example and Example 1 is that a chemical water reducer is added in this comparative example, and other conditions are the same.

[0029] Test example 1. According to the (GB / T 50081-2019) standard, test the 28d compressive strength of ecological concrete; Process: Cast 100mm×100mm×100mm test blocks, standard curing for 28 days (20±2℃, RH≥95%), load the pressure testing machine at a rate of 0.5MPa / s until failure, and take the average value of 3 test blocks.

[0030] 2. Test the interfacial bonding strength of ecological concrete according to the (JC / T 907-2002) standard; Procedure: Bond a 50mm diameter steel puller (epoxy resin cured for 24 hours) to the center of the concrete test block. Pull vertically at a rate of 0.1 MPa / s using a universal testing machine. Calculate: bond strength = maximum load / contact area.

[0031] 3. According to the (RCM method, GB / T 50082-2009) standard, test the ecological concrete permeability; Process: Drill a Φ100×50mm cylindrical specimen, soak it in a saturated Ca(OH)2 solution for 48 hours, apply a 60V DC voltage, and measure the current value after 30 minutes. The calculation formula is as follows: (T=temperature, L=thickness, U=voltage, t=time, = penetration depth).

[0032] 4. Test the freeze-thaw cycle durability of ecological concrete in accordance with the (GB / T 50082-2009) standard; Procedure: 100mm×100mm×400mm test blocks were saturated with water and subjected to rapid freeze-thaw cycles (-18℃~5℃, 4h per cycle). The transverse fundamental frequency was measured every 50 times. The relative dynamic elastic modulus was calculated using the following formula: ( = initial fundamental frequency, = fundamental frequency after n freeze-thaw cycles).

[0033] 5. According to the standard (HJ 700-2014), test the ecological concrete Adsorption rate; Procedure: Test block (50mm×50mm×50mm) is immersed in 5L of (5 mg / L) solution, run on a constant temperature oscillator (25°C, 120 r / min) for 30 days, and determine the solution residue by atomic absorption spectrometry concentration.

[0034] 6. According to the (HJ 636-2012) standard, test the TN removal rate of ecological concrete; Procedure: Prepare simulated sewage (TN = 4 mg / L, TP = 0.9 mg / L, COD = 83.4 mg / L), immerse the test block (100 mm × 100 mm × 100 mm) in 10 L of sewage, and use a constant temperature magnetic stirrer (30 r / min, 25°C). Take water samples on the 20th day, and measure TN by alkaline potassium persulfate digestion-UV spectrophotometry.

[0035] The specific data are as follows Table 1 and Table 2: Table 1 Table 2 From the data in the above table, we can see that: from the data of Examples 1-4 and Comparative Example 2, as the interface control component increases from 8 parts to 20 parts, The adsorption rate increased from 89.6% to 92.0%, and the TN removal rate increased from 85.0% to 88.0%. However, in Comparative Example 2, where no interface control component was added, the adsorption performance dropped sharply, demonstrating the synergistic adsorption effect of zeolite / steel slag powder. From the data of Example 1 and Comparative Example 1, it can be seen that the surface of the solid waste aggregate in Comparative Example 1 is not coated with an active solid waste microlayer, so that the interfacial bonding strength of the ecological concrete based on solid waste recycling is only 5.2 MPa, which is 40% lower than that of Example 1. The permeability increased by 62%, verifying the core role of the coated active solid waste microlayer in interface self-reinforcement; From the data of Example 1 and Comparative Example 3, it can be seen that although the compressive strength of the sample in Comparative Example 3 reached 43.5 MPa after adding a water reducer, the TN removal rate was only 65.0%, which was 20% lower than that in Example 1, because the chemical substances inhibited the activity of microorganisms. In summary, the present invention achieves the goal of coating the surface of solid waste aggregate with active solid waste microlayer and coordinating with interface control components, while ensuring mechanical properties, with a compressive strength of ≥39.5MPa. Permeability ≤1.6×× s, The adsorption rate is a breakthrough of ≥89.6%, and there are no chemical additives in the whole process.

[0036] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. An ecological concrete based on solid waste recycling, characterized by: The ecological concrete based on solid waste recycling is composed of the following raw materials in parts by weight: Portland cement: 20-26 parts; Solid waste aggregate: 22-29 parts; Interface control component: 8-20 parts; Water: 11-17 parts; The surface of the solid waste aggregate is coated with an active solid waste powder layer, and the coating layer has a thickness of 10-100 μm; The interface regulating component is composed of pH regulating solid waste and ion adsorption solid waste in a mass ratio of (2-4):

1.

2. The ecological concrete based on solid waste recycling according to claim 1, characterized in that: The active solid waste powder is at least one of fly ash, steel slag powder and metakaolin solid waste.

3. The ecological concrete based on solid waste recycling according to claim 1, characterized in that: The pH-controlled solid waste is at least one of steel slag powder, carbide slag, tailings powder and red mud.

4. The ecological concrete based on solid waste recycling according to claim 1, characterized in that: The ion-adsorption solid waste is at least one of zeolite solid waste, activated carbon-derived solid waste and modified red mud.

5. The ecological concrete based on solid waste recycling according to claim 1, characterized in that: The coating amount of the active solid waste fine powder layer is 5-12% of the mass of the solid waste aggregate.

6. The ecological concrete based on solid waste recycling according to claim 4, characterized in that: The zeolite solid waste is at least one of natural zeolite and coal gangue calcined zeolite.

7. The ecological concrete based on solid waste recycling according to claim 1, characterized in that: The solid waste aggregate is ceramsite made by sintering 19-25 parts of steel slag powder, 15-21 parts of phosphorus slag powder, 27-34 parts of plant fiber and 20-29 parts of sludge powder at 900-1200°C.

8. A method for preparing ecological concrete based on solid waste recycling, applicable to the ecological concrete based on solid waste recycling according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: mixing solid waste aggregate and active solid waste fine powder in a mass ratio of 100:(5-12) by weight, and subjecting the mixture to a mechanochemical treatment for 20-60 minutes to form a coating layer to obtain a pretreated aggregate; Step 2: Dry mix the Portland cement and interface control components for 60 seconds, then add water and pretreated aggregate to form a slurry; Step 3: Standard curing after slurry casting.

9. The method for preparing ecological concrete based on solid waste recycling according to claim 8, characterized in that: The rotation speed of the mechanochemical treatment in step 1 is 300-500 r / min.

10. The method for preparing ecological concrete based on solid waste recycling according to claim 8, characterized in that: The stirring time in the step 2 is 120-180s.

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