Preparation method of early-strength concrete with nanometer modified hole slag recycled aggregate

Abstract

The application discloses a preparation method of nano-modified hole slag recycled aggregate early-strength concrete, which comprises the following steps: (1) mixing hole slag recycled aggregate with tetraethyl orthosilicate modification liquid, separating the aggregate after static state, placing the aggregate in saturated limewater for heating, heat preservation and continuous stirring, screening the obtained aggregate after completion to obtain modified hole slag recycled coarse aggregate and modified hole slag recycled fine aggregate; (2) uniformly mixing magnesium phosphate cement, quicklime powder and nano silicon dioxide, granulating, and then coating a paraffin coating layer containing a calcium ion complexing agent on the surface of the obtained granular substance to obtain an early-strength agent; and (3) taking silicate cement, hole slag waste rock, water reducing agent, modified hole slag recycled coarse aggregate, fine aggregate and the early-strength agent, uniformly mixing the above raw materials, adding water and uniformly stirring to obtain the concrete. The nano repair technology is used to repair microcracks in the hole slag recycled aggregate, the workability and compressive strength of the concrete are effectively improved, and the utilization of the hole slag recycled aggregate is promoted.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, specifically to a method for preparing early-strength concrete using nano-modified recycled aggregate from quarry slag. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Mine waste rock refers to the stone material generated during the mining of tunnels and caves. It is often discarded or stockpiled as waste, and its large production volume not only occupies a significant amount of land resources but also easily pollutes the environment. By properly treating and processing this mine waste rock, it can be made into sand and gravel aggregates suitable for construction. This not only makes full use of the mine waste rock, reduces waste discharge, and lowers environmental pollution, achieving resource reuse, but it can also replace aggregates such as river sand and pebbles, alleviating the environmental problems caused by the mining of these aggregates.

[0004] Because cave slag and waste rock are forcefully cut from the rock mass by heavy machinery, the recycled aggregate formed from these materials contains numerous defects such as microcracks. These defects lead to decreased strength and increased water absorption in the recycled aggregate, which in turn reduces the hydration level and strength of the concrete. Therefore, recycled cave slag and waste rock are unsuitable for preparing high-strength concrete and are detrimental to the application of cave slag and waste rock. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for preparing early-strength concrete using nano-modified recycled cave slag aggregate. This method utilizes nanotechnology to repair microcracks in the recycled cave slag aggregate, effectively improving the compressive strength of the concrete and facilitating the application of recycled cave slag aggregate. Specifically, the technical solution of this invention is as follows.

[0006] A method for preparing early-strength concrete using nano-modified recycled aggregate from quarry debris includes the following steps: (1) After washing and drying the recycled aggregate from the slag, mix it with the tetraethyl orthosilicate modified liquid, separate the aggregate after standing, place it in saturated lime water, heat and keep it warm while stirring continuously, and after completion, screen the obtained aggregate to obtain modified recycled coarse aggregate and modified recycled fine aggregate from the slag, for later use.

[0007] (2) After mixing magnesium phosphate cement, quicklime powder and nano silica evenly, granulate them, and then coat the surface of the obtained particles with a paraffin coating layer containing calcium ion complexing agent to obtain an early strength agent.

[0008] (3) Take 160-220 parts by weight of silicate cement, 40-55 parts by weight of tunnel slag waste stone powder, 3-4.5 parts by weight of water-reducing agent, 570-780 parts by weight of the modified tunnel slag recycled coarse aggregate, 350-482 parts by weight of the modified tunnel slag recycled fine aggregate, and 25-33 parts by weight of early strength agent. Mix the above raw materials evenly, add water and mix well to obtain the concrete.

[0009] Further, in step (1), the ratio of the dried slag recycled aggregate to the tetraethyl orthosilicate modified liquid is 1g:15~30ml. Optionally, the tetraethyl orthosilicate modified liquid is prepared by mixing tetraethyl orthosilicate and anhydrous ethanol at a volume ratio of 2~3:1.

[0010] Furthermore, in step (1), the settling time is 1 to 2 hours so that the microcracks in the recycled aggregate can fully absorb the tetraethyl orthosilicate.

[0011] Further, in step (1), the ratio of aggregate to saturated lime water is 1g:40~70ml.

[0012] Furthermore, in step (1), the heating temperature is 50~70℃ and the heat preservation time is 8~10 hours.

[0013] Further, in step (2), the ratio of magnesium phosphate cement, quicklime powder, and nano-silica is 4.5~6 parts by weight: 1.1~1.5 parts by weight: 2~2.8 parts by weight. Optionally, the fineness of the quicklime powder is not less than 200 mesh.

[0014] Further, in step (2), the magnesium phosphate cement, quicklime powder, and nano-silica are mixed evenly, and then an anhydrous binder is added. The mixture is then granulated and dried to obtain the granules. Optionally, the particle size of the granules is 1-2 mm. The anhydrous binder includes glycerol, etc.

[0015] Further, in step (2), the calcium ion complexing agent is 25-30% of the mass of paraffin. Optionally, the calcium ion complexing agent includes ethylenediaminetetraacetic acid (EDTA). 10 H 16 N2O8), BAPTA tetrasodium salt (C 22 H 20 N2Na4O 10 At least one of the following:

[0016] Further, in step (2), the calcium ion complexing agent is added to the melted paraffin liquid and stirred evenly. Then, the resulting mixture is sprayed onto the surface of the particles for rolling coating. After completion, it is placed in an anhydrous solvent for stirring and cooling to obtain the early strength agent.

[0017] Further, the ratio of the particulate matter to the mixture is 1g:0.7~1.0ml. Preferably, the melting temperature of the paraffin wax does not exceed 80℃, such as 60~80℃.

[0018] Furthermore, the anhydrous solvent includes at least one of anhydrous methanol, anhydrous ethanol, etc.

[0019] Furthermore, in step (3), the particle size of the slag waste stone powder is 200~400 mesh. As a filler, it can fill the pores in the concrete, which not only helps to improve the compactness of the concrete, but also helps to utilize the slag waste stone powder.

[0020] Furthermore, in step (3), the water-reducing agent includes any one of polycarboxylate water-reducing agents, naphthalene-based water-reducing agents, lignosulfonate water-reducing agents, aliphatic water-reducing agents, etc.

[0021] Furthermore, in step (3), the amount of water added is based on a water-cement ratio of 0.4 to 0.44.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects: First, this invention mixes recycled cave slag aggregate with tetraethyl orthosilicate (TEA) modified liquid, loading the microcracks and surface of the recycled aggregate with TEA. Then, the aggregate is heated and kept at a constant temperature in saturated lime water. The TEA hydrolyzes in the alkaline environment of the lime water to form nano-silica. These highly active nanoparticles further react with calcium hydroxide provided by the lime water to form calcium silicate hydrate. This cementitious filler repairs the microcracks in the recycled aggregate, improving aggregate strength and reducing water absorption, thereby enhancing the mechanical strength of the prepared concrete. Simultaneously, the partially free calcium silicate hydrate, after being incorporated into the concrete along with the recycled aggregate, acts as a nucleating agent, promoting the hydration reaction of silicate cement and contributing to improved early-stage strength of the concrete.

[0023] Furthermore, the concrete material of the present invention also contains a core-shell early-strength agent prepared from a core formed by the magnesium phosphate cement, quicklime powder, and nano-silica, and a coating layer formed by a calcium ion complexing agent and paraffin wax. After the early-strength agent enters the concrete, the calcium ion complexing agent dissolves and distributes within the concrete under the action of mixing water, thus making the coating layer a porous structure. When mixing water passes through, it reacts with the quicklime powder inside, releasing heat and causing the paraffin wax coating layer to melt and break down. Simultaneously, the calcium oxide reacts with water to form calcium hydroxide, which also expands in volume, further damaging the paraffin wax coating layer. At this time, the magnesium phosphate cement is exposed in the concrete and undergoes a hydration reaction with the mixing water. Since the rate of this hydration reaction is much faster than that of the silicate cement, and the hydration cementitious products formed by the magnesium phosphate cement have high strength and high adhesion, their distribution in the concrete matrix as a skeleton can rapidly improve the early strength of the concrete. At the same time, the calcium hydroxide formed by the quicklime and the nano-calcium oxide undergo a hydration reaction to form hydrated calcium silicate, increasing the content of cementitious components in the concrete and improving the mechanical strength of the concrete. Furthermore, the calcium ion complexing agent dissolved in the concrete can complex calcium ions produced during the hydration of silicate cement, reducing the calcium ion concentration and thus promoting the hydration reaction and improving the early strength of the concrete. Additionally, the paraffin wax distributed and filling the pores of the concrete structure also helps to improve its waterproof and impermeable properties. Attached Figure Description

[0024] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings, wherein: Figure 1 The image shows a sample of the recycled aggregate from the quarry used in Example 1 of the present invention.

[0025] Figure 2 The image shows a sample of the modified recycled coarse aggregate from the slag in Example 1 of this invention. Detailed Implementation

[0026] The technical solution of the present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0027] Example 1 A method for preparing early-strength concrete using nano-modified recycled aggregate from quarry debris includes the following steps: (1) Recycled aggregate from quarry slag (such as...) Figure 1(As shown) After washing away the mud with clean water, the aggregate was air-dried at room temperature for 2 days. Then, the recycled aggregate was mixed with tetraethyl orthosilicate modified liquid (made by mixing tetraethyl orthosilicate and anhydrous ethanol at a volume ratio of 3:1) at a ratio of 1g:20ml. After stirring, the mixture was allowed to stand for 1.5 hours. The aggregate was then filtered to separate it. This mixture was then mixed with saturated lime water at a ratio of 1g:60ml. The mixture was then heated to 50℃ and kept at that temperature for 9 hours, with continuous stirring during the heating process. After the heating was completed, the aggregate was filtered, sieved, and then air-dried. The aggregate with a particle size of 0.5~2mm was designated as modified recycled fine aggregate, and the aggregate with a particle size of 10~30mm was designated as modified recycled coarse aggregate (e.g., Figure 2 (As shown), for later use.

[0028] (2) Take 5.5 parts by weight of magnesium phosphate cement powder (formed by potassium dihydrogen phosphate and calcined magnesium oxide in a mass ratio of 1:3), 1.3 parts by weight of 200-mesh quicklime powder, and 2.5 parts by weight of nano silica. Mix them evenly and add anhydrous binder glycerol. Stir evenly and granulate. Dry the obtained particles with a particle size of 1~2 mm at 75℃ for 20 min to obtain the core particles.

[0029] (3) Add 30% by weight of ethylenediaminetetraacetic acid powder to the molten paraffin at 70℃, and stir quickly to mix evenly to obtain a coating solution. Spray the coating solution onto the core particles at a ratio of 1g:0.8ml and roll to coat them. After completion, place the obtained particles in anhydrous ethanol, stir and cool, then separate the particles and let them air dry to obtain the early strength agent for later use.

[0030] (4) Take the following raw materials in parts by weight: 210 parts of 42.5 ordinary Portland cement, 50 parts of 300-mesh tunnel slag waste stone powder, 4 parts of polycarboxylate superplasticizer, 650 parts of modified tunnel slag recycled coarse aggregate of this embodiment, 420 parts of modified tunnel slag recycled fine aggregate of this embodiment, and 28 parts of early strength agent of this embodiment. Mix the above raw materials evenly, add 110 parts by weight of clean water, stir for 2 minutes, and the concrete is obtained.

[0031] The 1-day compressive strength (early compressive strength) of the specimens prepared from the concrete described in this embodiment was tested according to the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" (GB / T 50081-2016). The water resistance of the 28-day-aged specimens prepared from the concrete described in this embodiment was tested according to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T 50082-2009). The test results were: 1-day compressive strength of 18.27 MPa, and water penetration height of 5.1 mm.

[0032] Example 2 A method for preparing early-strength concrete using nano-modified recycled aggregate from quarry debris includes the following steps: (1) After washing the recycled cave slag aggregate with clean water to remove mud, air-dry it at room temperature for 3 days. Then, mix the recycled cave slag aggregate with tetraethyl orthosilicate modified liquid (made by mixing tetraethyl orthosilicate and anhydrous ethanol at a volume ratio of 2:1) at a material-liquid ratio of 1g:30ml. After stirring, let it stand for 1 hour, then filter to separate the aggregate. Mix it with saturated lime water at a material-liquid ratio of 1g:70ml, then heat it to 60℃ and keep it at that temperature for 10 hours, while continuously stirring during the heat preservation process. After the heat preservation is completed, filter the aggregate, sieve it, and air-dry it. The aggregate with a particle size of 0.5~2mm is used as modified recycled cave slag fine aggregate, and the aggregate with a particle size of 10~30mm is used as modified recycled cave slag coarse aggregate, for later use.

[0033] (2) Take 6 parts by weight of magnesium phosphate cement powder (formed by potassium dihydrogen phosphate and calcined magnesium oxide in a mass ratio of 1:3.5), 1.5 parts by weight of 400-mesh quicklime powder, and 2.8 parts by weight of nano silica. Mix them evenly and then add an anhydrous binder formed by glycerol and anhydrous ethanol in a ratio of 1:1 (v:v). Stir evenly and then granulate. Dry the resulting particles with a particle size of 1~2 mm at 75℃ for 20 min to obtain the core particles.

[0034] (3) Add 25% by weight of ethylenediaminetetraacetic acid powder to the molten paraffin at 80℃, and stir quickly to mix evenly to obtain a coating solution. Spray the coating solution onto the core particles at a ratio of 1g:1.0ml and roll to coat them. After completion, place the obtained particles in anhydrous ethanol, stir and cool, then separate the particles and let them air dry to obtain the early strength agent for later use.

[0035] (4) Take the following raw materials in parts by weight: 160 parts of 42.5 ordinary Portland cement, 40 parts of 200-mesh tunnel slag waste stone powder, 3 parts of polycarboxylate superplasticizer, 570 parts of modified tunnel slag recycled coarse aggregate of this embodiment, 350 parts of modified tunnel slag recycled fine aggregate of this embodiment, and 25 parts of early strength agent of this embodiment. Mix the above raw materials evenly, add 80 parts by weight of clean water, and stir for 2 minutes to obtain the concrete.

[0036] The 1-day compressive strength (early compressive strength) of the specimens prepared from the concrete described in this embodiment was tested according to the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" (GB / T 50081-2016). The water resistance of the 28-day-aged specimens prepared from the concrete described in this embodiment was tested according to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T 50082-2009). The test results were: 1-day compressive strength of 17.04 MPa, and water penetration height of 4.7 mm.

[0037] Example 3 A method for preparing early-strength concrete using nano-modified recycled aggregate from quarry debris includes the following steps: (1) After washing the recycled cave slag aggregate with clean water to remove mud, air-dry it at room temperature for 3 days. Then, mix the recycled cave slag aggregate with tetraethyl orthosilicate modified liquid (made by mixing tetraethyl orthosilicate and anhydrous ethanol at a volume ratio of 2.5:1) at a material-liquid ratio of 1g:15ml. After stirring, let it stand for 2 hours. Then filter to separate the aggregate. Mix it with saturated lime water at a material-liquid ratio of 1g:40ml. Then heat to 70℃ and keep it at that temperature for 8 hours, while continuously stirring during the heat preservation process. After the heat preservation is completed, filter the aggregate, sieve it and air-dry it. The aggregate with a particle size of 0.5~2mm is used as modified recycled cave slag fine aggregate, and the aggregate with a particle size of 10~30mm is used as modified recycled cave slag coarse aggregate, which are used for later use.

[0038] (2) Take 4.5 parts by weight of magnesium phosphate cement powder (formed by potassium dihydrogen phosphate and calcined magnesium oxide in a mass ratio of 1:3), 1.15 parts by weight of 400-mesh quicklime powder, and 2 parts by weight of nano silica. Mix them evenly and then add an anhydrous binder formed by glycerol and anhydrous ethanol in a ratio of 1:1 (v:v). Stir evenly and then granulate. Dry the resulting particles with a particle size of 1~2 mm at 75℃ for 20 min to obtain the core particles.

[0039] (3) Add 30% by weight of BAPTA tetrasodium salt powder to the molten paraffin at 70℃, and stir quickly to mix evenly to obtain a coating solution. Spray the coating solution onto the core particles at a ratio of 1g:0.7ml and roll to coat them. After completion, place the obtained particles in anhydrous methanol, stir and cool, then separate the particles and let them air dry to obtain the early strength agent for later use.

[0040] (4) Take the following raw materials in parts by weight: 220 parts of 42.5 ordinary Portland cement, 55 parts of 400-mesh slag waste stone powder, 4.5 parts of sodium lignosulfonate water-reducing agent, 780 parts of modified slag recycled coarse aggregate of this embodiment, 482 parts of modified slag recycled fine aggregate of this embodiment, and 33 parts of early strength agent of this embodiment. Mix the above raw materials evenly, add 121 parts by weight of clean water, stir for 2 minutes, and the concrete is obtained.

[0041] The 1-day compressive strength (early compressive strength) of the concrete specimens prepared according to the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" (GB / T 50081-2016) was tested. The water resistance of the 28-day-aged specimens prepared according to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T50082-2009) was tested. The test results were: 1-day compressive strength of 17.66 MPa, and water penetration height of 5.8 mm.

[0042] Example 4 A method for preparing early-strength concrete using nano-modified recycled aggregate from quarry debris includes the following steps: (1) Wash the recycled aggregate of the slag with clean water to remove mud and air dry it at room temperature for 2 days. Then, sieve it and air dry it. The aggregate with a particle size of 0.5~2mm is used as the recycled fine aggregate of the slag, and the aggregate with a particle size of 10~30mm is used as the recycled coarse aggregate of the slag.

[0043] (2) Take the following raw materials in parts by weight: 210 parts of 42.5 ordinary Portland cement, 50 parts of 300-mesh tunnel slag waste stone powder, 4 parts of polycarboxylate superplasticizer, 650 parts of recycled tunnel slag coarse aggregate in this embodiment, and 420 parts of recycled tunnel slag fine aggregate in this embodiment. Mix the above raw materials evenly, add 110 parts by weight of clean water, and stir for 2 minutes to obtain the concrete.

[0044] The 1-day compressive strength (early compressive strength) of the specimens prepared from the concrete described in this embodiment was tested according to the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" (GB / T 50081-2016). The water resistance of the 28-day-aged specimens prepared from the concrete described in this embodiment was tested according to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T 50082-2009). The test results were: 1-day compressive strength of 9.73 MPa, and water penetration height of 35.2 mm.

[0045] Example 5 A method for preparing early-strength concrete using nano-modified recycled aggregate from quarry debris includes the following steps: (1) After washing the recycled aggregate of the cave slag with clean water to remove mud, air dry it at room temperature for 2 days. Then, mix the recycled aggregate of the cave slag with the tetraethyl orthosilicate modified liquid (made by mixing tetraethyl orthosilicate and anhydrous ethanol at a volume ratio of 3:1) at a material-liquid ratio of 1g:20ml. After stirring, let it stand for 1.5 hours. Then filter to separate the aggregate, sieve it and air dry it. The aggregate with a particle size of 0.5~2mm is used as the modified recycled fine aggregate of the cave slag, and the aggregate with a particle size of 10~30mm is used as the modified recycled coarse aggregate of the cave slag, for later use.

[0046] (2) Take the following raw materials in parts by weight: 210 parts of 42.5 ordinary Portland cement, 50 parts of 300-mesh tunnel slag waste stone powder, 4 parts of polycarboxylate superplasticizer, 650 parts of modified tunnel slag recycled coarse aggregate of this embodiment, 420 parts of modified tunnel slag recycled fine aggregate of this embodiment, and 28 parts of the early strength agent of Example 1. Mix the above raw materials evenly, add 110 parts by weight of clean water, stir for 2 minutes, and the concrete is obtained.

[0047] The 1-day compressive strength (early compressive strength) of the concrete specimens prepared according to the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" (GB / T 50081-2016) was tested. The water resistance of the 28-day-aged specimens prepared according to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T 50082-2009) was tested. The test results were: 1-day compressive strength of 15.15 MPa, and water penetration height of 10.3 mm.

[0048] Example 6 A method for preparing early-strength concrete using nano-modified recycled aggregate from quarry debris includes the following steps: (1) Take 4.5 parts by weight of magnesium phosphate cement powder (formed by potassium dihydrogen phosphate and calcined magnesium oxide in a mass ratio of 1:3) and 2 parts by weight of nano silica. Mix them evenly and add anhydrous glycerol binder. Stir evenly and granulate. Dry the resulting particles with a particle size of 1~2 mm at 75℃ for 20 min to obtain the core particles.

[0049] (2) Add 30% by weight of BAPTA tetrasodium salt powder to the molten paraffin at 70℃, and stir quickly to mix evenly to obtain a coating solution. Spray the coating solution onto the core particles at a ratio of 1g:0.7ml and roll to coat them. After completion, place the obtained particles in anhydrous methanol, stir and cool, then separate the particles and let them air dry to obtain the early strength agent for later use.

[0050] (3) Take the following raw materials in parts by weight: 220 parts of 42.5 ordinary Portland cement, 55 parts of 400-mesh slag waste stone powder, 4.5 parts of sodium lignosulfonate water-reducing agent, 780 parts of modified slag recycled coarse aggregate from Example 3, 482 parts of modified slag recycled fine aggregate from Example 3, and 33 parts of the early-strength agent of this example. Mix the above raw materials evenly, add 121 parts by weight of clean water, and stir for 2 minutes to obtain the concrete.

[0051] The 1-day compressive strength (early compressive strength) of the concrete specimens prepared according to the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" (GB / T 50081-2016) was tested. The water resistance of the 28-day-aged specimens prepared from the concrete of this embodiment was tested according to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T 50082-2009). The test results were: 1-day compressive strength of 14.25 MPa, and water penetration height of 15.4 mm.

[0052] Example 7 A method for preparing early-strength concrete using nano-modified recycled aggregate from quarry debris includes the following steps: (1) Use molten paraffin at 80°C as coating liquid, and then spray the coating liquid onto the core particles (same as in Example 2 above) at a ratio of 1g:1.0ml and roll coating. After completion, place the obtained particles in anhydrous ethanol, stir and cool, then separate the particles and air dry them naturally to obtain the early strength agent for later use.

[0053] (2) Take the following raw materials in parts by weight: 160 parts of 42.5 ordinary Portland cement, 40 parts of 200-mesh tunnel slag waste stone powder, 3 parts of polycarboxylate superplasticizer, 570 parts of modified tunnel slag recycled coarse aggregate from Example 2, 350 parts of modified tunnel slag recycled fine aggregate from Example 2, and 25 parts of the early strength agent of this example. Mix the above raw materials evenly, add 80 parts by weight of clean water, and stir for 2 minutes to obtain the concrete.

[0054] The 1-day compressive strength (early compressive strength) of the concrete specimens prepared according to the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" (GB / T 50081-2016) was tested. The water resistance of the 28-day-aged specimens prepared from the concrete of this embodiment was tested according to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T 50082-2009). The test results were: 1-day compressive strength of 12.79 MPa, and water penetration height of 24.2 mm.

[0055] Example 8 A method for preparing early-strength concrete using nano-modified recycled aggregate from quarry debris includes the following steps: (1) Take 4.5 parts by weight of magnesium phosphate cement powder (formed by potassium dihydrogen phosphate and calcined magnesium oxide in a mass ratio of 1:3) and 1.15 parts by weight of 400-mesh quicklime powder, mix them evenly, add anhydrous glycerol binder, stir evenly and granulate, and dry the resulting particles with a particle size of 1~2mm at 75℃ for 20min to obtain the core particles.

[0056] (2) Add 30% by weight of BAPTA tetrasodium salt powder to the molten paraffin at 70℃, and stir quickly to mix evenly to obtain a coating solution. Spray the coating solution onto the core particles at a ratio of 1g:0.7ml and roll to coat them. After completion, place the obtained particles in anhydrous methanol, stir and cool, then separate the particles and let them air dry to obtain the early strength agent for later use.

[0057] (3) Take the following raw materials in parts by weight: 220 parts of 42.5 ordinary Portland cement, 55 parts of 400-mesh slag waste stone powder, 4.5 parts of sodium lignosulfonate water-reducing agent, 780 parts of modified slag recycled coarse aggregate from Example 3, 482 parts of modified slag recycled fine aggregate from Example 3, and 33 parts of the early-strength agent of this example. Mix the above raw materials evenly, add 121 parts by weight of clean water, and stir for 2 minutes to obtain the concrete.

[0058] The 1-day compressive strength (early compressive strength) of the concrete specimens prepared according to the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" (GB / T 50081-2016) was tested. The water resistance of the 28-day-aged specimens prepared from the concrete of this embodiment was tested according to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T 50082-2009). The test results were: 1-day compressive strength of 16.47 MPa, and water penetration height of 6.6 mm.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing early-strength concrete using nano-modified recycled aggregate from quarry debris, characterized in that, The steps include the following: (1) After washing and drying the recycled aggregate from the slag, mix it with the tetraethyl orthosilicate modified liquid, separate the aggregate after standing, place it in saturated lime water, heat and keep it warm while stirring continuously, and after completion, screen the obtained aggregate to obtain modified recycled coarse aggregate and modified recycled fine aggregate from the slag, for later use. (2) After mixing magnesium phosphate cement, quicklime powder and nano silica evenly, granulate them, and then coat the surface of the obtained particles with a paraffin coating layer containing calcium ion complexing agent to obtain an early strength agent. (3) Take 160-220 parts by weight of silicate cement, 40-55 parts by weight of cave slag waste stone powder, 3-4.5 parts by weight of water-reducing agent, 570-780 parts by weight of the modified cave slag recycled coarse aggregate, 350-482 parts by weight of the modified cave slag recycled fine aggregate, and 25-33 parts by weight of early strength agent; mix the above raw materials evenly and then add water to mix evenly to obtain the concrete.

2. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 1, characterized in that, In step (1), the ratio of the dried slag recycled aggregate to the tetraethyl orthosilicate modified liquid is 1g:15~30ml.

3. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 1, characterized in that, The tetraethyl orthosilicate modified solution is prepared by mixing tetraethyl orthosilicate and anhydrous ethanol at a volume ratio of 2 to 3:

1.

4. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 1, characterized in that, In step (1), the ratio of aggregate to saturated lime water is 1g:40~70ml.

5. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 1, characterized in that, In step (1), the heating temperature is 50~70℃ and the holding time is 8~10 hours.

6. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 1, characterized in that, In step (2), the ratio of magnesium phosphate cement, quicklime powder and nano silica is 4.5~6 parts by weight: 1.1~1.5 parts by weight: 2~2.8 parts by weight.

7. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 1, characterized in that, In step (2), the fineness of the quicklime powder is not less than 200 mesh.

8. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 1, characterized in that, In step (2), the magnesium phosphate cement, quicklime powder, and nano silica are mixed evenly and then an anhydrous binder is added. The mixture is then granulated and dried to obtain the granules.

9. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 8, characterized in that, The particle size of the particulate matter is 1~2mm.

10. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 8, characterized in that, The anhydrous binder includes glycerin.

11. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 1, characterized in that, In step (2), the calcium ion complexing agent is 25-30% of the mass of paraffin.

12. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 1, characterized in that, The calcium ion complexing agent includes at least one of ethylenediaminetetraacetic acid (EDTA) and tetrasodium BAPTA.

13. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 1, characterized in that, In step (2), the calcium ion complexing agent is added to the melted paraffin liquid and stirred evenly. Then, the resulting mixture is sprayed onto the surface of the particles for rolling coating. After completion, it is placed in an anhydrous solvent for stirring and cooling to obtain the early strength agent.

14. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 13, characterized in that, The ratio of the particulate matter to the mixture is 1g:0.7~1.0ml.

15. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 13, characterized in that, The melting temperature of the paraffin does not exceed 80°C.

16. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 15, characterized in that, The melting temperature of the paraffin is 60~80℃.

17. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to claim 13, characterized in that, The anhydrous solvent includes at least one of anhydrous methanol and anhydrous ethanol.

18. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to any one of claims 1-17, characterized in that, In step (3), the water-reducing agent includes any one of polycarboxylate water-reducing agent, naphthalene-based water-reducing agent, lignosulfonate water-reducing agent, and aliphatic water-reducing agent.

19. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to any one of claims 1-17, characterized in that, In step (3), the particle size of the slag waste stone powder is 200~400 mesh.

20. The method for preparing early-strength concrete using nano-modified recycled aggregate from quarry waste according to any one of claims 1-17, characterized in that, In step (3), the amount of water added is based on a water-cement ratio of 0.4 to 0.44.

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