High-strength concrete based on building solid waste regeneration and preparation process thereof

Abstract

The application relates to the technical field of solid waste regenerated concrete, and discloses high-strength concrete based on building solid waste regeneration and a preparation process thereof, which comprises the following raw materials in parts by mass: cement 280-320 parts, regenerated coarse aggregate 300-320 parts, regenerated fine aggregate 280-300 parts, river sand 40-50 parts, mineral powder 50-60 parts, fly ash 55-65 parts, basalt gravel 30-40 parts, composite red brick powder 20-30 parts, water reducing agent 2-3 parts and water 130-150 parts. Through recycling of waste concrete, the waste concrete is broken again, regenerated coarse aggregate and regenerated fine aggregate are collected, part of fly ash, mineral powder, river sand and basalt gravel traditional admixtures are replaced, red brick powder (adopted red brick after building demolition) is used as modified filler, and the building waste is used as regenerated aggregate to manufacture regenerated concrete, so that the concrete formed by the regenerated concrete has high mechanical strength and impermeability.

Description

Technical Field

[0001] This invention relates to the field of recycled solid waste concrete technology, specifically to a high-strength concrete based on recycled construction solid waste and its preparation process. Background Technology

[0002] Construction solid waste mainly includes crushed concrete blocks, waste wood products, and waste sintered clay bricks. These solid waste materials can be processed into recycled coarse and fine aggregates through crushing, impurity removal, grading, and screening. Recycled high-strength concrete made from these recycled coarse and fine aggregates has high mechanical strength and fully recycles solid waste, which is of great significance to the sustainable development strategy. Among them, red brick powder, which contains ferric oxide, mainly comes from red building bricks made from clay and is one of the main building materials. This leads to a large proportion of crushed red bricks in demolition construction waste. Therefore, using construction waste as recycled aggregate to manufacture recycled concrete is conducive to reducing carbon emissions in urban construction and achieving environmental protection and sustainable development.

[0003] Using construction waste (waste red brick powder) to replace part of the cement in concrete preparation can reduce the cost of concrete and the prepared concrete has better performance. However, as a type of recycled micro powder with high silica content, waste red brick powder contains a large number of pore structures and is easy to absorb water, resulting in poor impermeability and mechanical strength of the concrete material. Summary of the Invention

[0004] This invention provides a high-strength concrete based on the recycling of construction solid waste and its preparation process, which solves the problem that the porous structure of waste red brick powder easily absorbs water, resulting in poor impermeability and mechanical strength of concrete materials.

[0005] The technical solution of this invention:

[0006] A high-strength concrete based on recycled construction solid waste comprises the following raw materials by weight: 280-320 parts cement, 300-320 parts recycled coarse aggregate, 280-300 parts recycled fine aggregate, 40-50 parts river sand, 50-60 parts mineral powder, 55-65 parts fly ash, 30-40 parts basalt crushed stone, 20-30 parts composite red brick powder, 2-3 parts water-reducing agent, and 130-150 parts water.

[0007] The composite red brick powder is obtained by grafting dichlorodimethylsilane onto epoxy resin, and then reacting it with modified red brick powder and ethylenediamine.

[0008] The modified red brick powder is obtained by mixing red brick powder with calcium chloride and sodium carbonate, reacting and calcining, and then surface-treating with a silane coupling agent.

[0009] A process for preparing high-strength concrete based on recycled construction solid waste includes the following preparation steps:

[0010] Cement, recycled coarse aggregate, recycled fine aggregate, river sand, mineral powder, fly ash, basalt crushed stone and composite red brick powder are mixed to form a mixture. Water-reducing agent and water are added to the mixture and stirred at a rate of 80-120 r / min for 3-5 min to obtain high-strength concrete.

[0011] Furthermore, the apparent density of the river sand is 2660-2690 kg / m³. 3 The fineness modulus is 2.3-2.5, the particle size is 0.15-4.75mm, and the mud content is 0.8-1.3%.

[0012] Furthermore, the mineral powder is S95 grade mineral powder with an apparent density of 2.8-2.9 g / cm³. 3 Specific surface area is 450-500 m² 2 / kg, moisture content is 0.2-1%, particle size is 20-50μm.

[0013] Furthermore, the basalt gravel has a continuous gradation of 5-25mm and a mud content of 0.1-0.3%.

[0014] Furthermore, the fly ash is Class F Grade I fly ash, with a fineness of 10-20 μm, a loss on ignition of 2.6-2.9%, and a moisture content of 0.1-0.2%.

[0015] Furthermore, the water-reducing agent is a polycarboxylate water-reducing agent.

[0016] Furthermore, the composite red brick powder is prepared by the following steps:

[0017] A1. Mix calcium chloride aqueous solution and sodium carbonate ethylene glycol solution evenly, add red brick powder, stir and adsorb, stir and react at 1000-1200 r / min and 20-25℃ for 2-3 h, filter, wash, dry, place in tube furnace, heat to 900-1100℃ at a heating rate of 5-10℃ / min, keep at the temperature for 4-6 h, cool to room temperature to obtain red brick powder loaded with calcium silicate;

[0018] A2. Mix red brick powder loaded with calcium silicate and sodium carboxymethyl cellulose solution, stir, remove, dry, then add to ethanol and deionized water, stir evenly, add silane coupling agent, stir reaction at 70-80℃ for 1-2 hours, filter, wash, dry to obtain modified red brick powder;

[0019] A3. Mix epoxy resin and ethyl acetate, stir until the epoxy resin is fully dissolved, add dibutyltin dilaurate and dichlorodimethylsilane, stir and react at 50-55℃ for 1-2 hours. During the reaction, triethylamine is used to remove the hydrogen chloride produced in the reaction. The mass of triethylamine is 10% of the mass of epoxy resin E-51. After the reaction is completed, collect the product by centrifugation, wash the product and then perform vacuum distillation to obtain organosilicon modified epoxy resin.

[0020] A4. Mix organosilicon-modified epoxy resin and acetone, stir evenly, add modified red brick powder and ethylenediamine, stir at 20-25℃ and 2800-3000r / min for 1-2h, then raise the temperature to 90-100℃ and stir for 1-1.5h. After filtration, washing and drying, composite red brick powder is obtained.

[0021] Furthermore, in the above A1 reaction process, the calcium chloride aqueous solution and the sodium carbonate ethylene glycol solution are mixed to form a mixed solution. The red brick powder has a porous structure and high adsorption performance, which can adsorb calcium ions in the mixed solution into the pores of the red brick powder. Sodium carbonate provides carbonate ions, which react with calcium ions to form calcium carbonate, thus achieving the synthesis of calcium carbonate in the pores of the red brick powder. In a tube furnace, the heating rate is 5-10℃ / min, and the temperature is raised to 800-1100℃ and held for 2-6 hours. The calcium carbonate synthesized in the pores of the red brick powder can react with the silicon dioxide in the red brick powder to form calcium silicate, thus obtaining red brick powder loaded with calcium silicate.

[0022] Furthermore, during the A2 reaction process described above, sodium carboxymethyl cellulose exhibits good adhesion, enabling it to adhere to the surface of red brick powder loaded with calcium silicate, thereby imparting active groups to the red brick powder. Additionally, the silanol groups generated by the hydrolysis of the silane coupling agent can chemically bond with the carboxyl groups on the surface of the red brick powder loaded with calcium silicate, thus grafting the silane coupling agent onto the surface of the red brick powder loaded with calcium silicate, resulting in modified red brick powder.

[0023] Furthermore, in the A3 reaction process described above, dibutyltin dilaurate acts as a catalyst, causing dichlorodimethylsilane to react with the hydroxyl groups on the epoxy resin molecular chain, weakening the hydrophilic hydroxyl groups of the epoxy resin and introducing the hydrophobic methyl groups to obtain organosilicon-modified epoxy resin. In this process, the organosilicon only reacts with the hydroxyl groups of the epoxy resin, while the epoxy groups do not participate in the reaction, enabling the modified epoxy resin to form a dense cross-linked network structure on the surface of the modified red brick powder.

[0024] Furthermore, in the A4 reaction process described above, ethylenediamine acts as a crosslinking agent. The amine groups it contains can undergo crosslinking reactions with the epoxy groups on the molecular chains of the organosilicon-modified epoxy resin. In addition, the amine groups of ethylenediamine can also combine with the epoxy groups on the surface of the modified red brick powder, so that the organosilicon-modified epoxy resin with a crosslinked network structure is coated on the surface of the modified red brick powder, thus obtaining composite red brick powder.

[0025] Further, in step A1, the concentration of the calcium chloride aqueous solution is 0.04-0.06 mol / L; the concentration of the sodium carbonate ethylene glycol solution is 0.04-0.06 mol / L; and the mass ratio of the calcium chloride aqueous solution, the sodium carbonate ethylene glycol solution, and the red brick powder is (40-50):(40-50):(2.5-3).

[0026] Further, in step A2, the mass ratio of the calcium silicate-loaded red brick powder, sodium carboxymethyl cellulose solution, ethanol, deionized water, and silane coupling agent is (2.2-2.5):(20-30):(90-100):(30-40):(0.5-0.7).

[0027] Further, in step A3, the mass ratio of epoxy resin, ethyl acetate, dibutyltin dilaurate, and dichlorodimethylsilane is (8-10):(10-12):(0.04-0.06):(0.7-0.8).

[0028] Further, in step A4, the mass ratio of the organosilicon-modified epoxy resin, ethanol, modified red brick powder, and ethylenediamine is (0.4-0.5):(5-10):(2-2.2):(0.02-0.04).

[0029] The present invention has the following beneficial effects:

[0030] (1) In the technical solution of the present invention, calcium silicate is synthesized in the pores of red brick powder. On the one hand, the synthesized calcium silicate can fill the pores of red brick powder, reduce the porosity of red brick powder, weaken the water absorption performance of red brick powder, and calcium silicate is insoluble in water and has high waterproof performance. A waterproof layer is formed in the pores and surface of red brick powder to avoid red brick powder having a porous structure that easily absorbs water, resulting in poor impermeability of concrete materials and affecting the mechanical strength of concrete. On the other hand, as a hydration product of cement, calcium silicate added to concrete can significantly improve the compressive strength of concrete.

[0031] (2) In the technical solution of this invention, the silane coupling agent is grafted onto the surface of the red brick powder loaded with calcium silicate, introducing epoxy groups and organosilicon segments onto the surface of the red brick powder. This facilitates the coating of the organosilicon-modified epoxy resin onto the surface of the red brick powder, improves the acid and alkali resistance of the red brick powder, and avoids the calcium silicate in the red brick powder from easily reacting and decomposing with acid under acidic conditions, which would cause the porous structure of the red brick powder to easily absorb water, destroy the dense structure of the concrete, and reduce the mechanical strength and impermeability of the concrete. The use of dichlorodimethylsilane grafting to modify the epoxy resin can weaken the... The hydrophilic hydroxyl groups on the epoxy resin molecular chain, along with the introduction of hydrophobic methyl groups, enhance the hydrophobicity of the epoxy resin. Furthermore, the introduced Si-O and Si-O-Si bonds enable the silicone-modified epoxy resin to effectively absorb and disperse impact forces when subjected to external shocks. When added to concrete, it improves the mechanical strength of the concrete. In addition, since no epoxy groups are lost during the process, the modified epoxy resin maintains a good crosslinking density, allowing it to coat the surface of modified red brick powder and improve its acid and alkali resistance.

[0032] (3) In the technical solution of the present invention, the organosilicon-modified epoxy resin is coated on the surface of the modified red brick powder with ethylenediamine. On the one hand, the organosilicon-modified epoxy resin can prevent acidic media from penetrating into the interior of the modified red brick powder and corroding and dissolving the calcium silicate inside the modified red brick powder, thus avoiding the calcium silicate in the red brick powder from easily reacting and decomposing with acid under acidic conditions, which would cause the porous structure of the red brick powder to easily absorb water, thus reducing the mechanical strength and impermeability of the concrete. On the other hand, the hydrophobic segments contained in the organosilicon-modified epoxy resin form a waterproof layer along the capillary pores in the concrete, so that after the concrete is cured, it can reduce the penetration of water and corrosive media through the capillary pores, block the penetration of water, acidic media and harmful ions, and improve the impermeability of the concrete. In addition, the organosilicon-modified epoxy resin on the surface of the composite red brick powder presents a cross-linked network structure, and the concrete substrate can penetrate into the cross-linked network structure, so that the composite red brick powder is evenly dispersed in the concrete, thereby improving the mechanical strength and impermeability of the concrete.

[0033] (4) In the technical solution of the present invention, waste concrete is recycled and then crushed to collect recycled coarse aggregate and recycled fine aggregate, which replace part of the traditional admixtures such as fly ash, mineral powder, river sand and basalt crushed stone, and reduce the amount of cement used, thereby reducing carbon emissions from cement production and reducing the cost of concrete raw materials. Red brick powder (using red bricks after building demolition) is used as a modified filler, and the concrete formed with recycled coarse aggregate, recycled fine aggregate, fly ash, mineral powder, river sand and basalt crushed stone has high mechanical strength and impermeability. Moreover, the use of construction waste as recycled aggregate to manufacture recycled concrete is conducive to reducing carbon emissions in urban construction and realizing environmental protection and sustainable development. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] The raw materials used in the embodiments of this invention are shown below, and all reagents used are analytical grade.

[0036] Among them, recycled coarse aggregate and recycled fine aggregate: waste concrete is processed into blocks with a side length of 130mm, surface debris, dust and impurities are removed, and dried at 70℃ for 10min. The blocks are then crushed in a jaw crusher, and the crushed aggregate is screened. Aggregates that do not meet the particle size distribution requirements are put back into the jaw crusher for secondary crushing. Recycled coarse aggregate and recycled fine aggregate are collected separately.

[0037] The recycled coarse aggregate has a continuous gradation of 5-20mm, a water absorption rate of ≤6%, and a crushing index of ≤10%; the recycled fine aggregate has a fineness modulus of 2.5-3.0, a MB value of ≤1.4, and a crushing index of ≤15%.

[0038] Red brick powder is made from red bricks after building demolition. After removing surface debris, dust and impurities, the bricks are crushed and ball-milled for 30 minutes using a planetary ball mill. The powder is then screened (the screening process involves passing through a 45μm square hole sieve, with a residue of 8.5%).

[0039] Red brick powder, by weight percentage, comprises: 63.82% silicon dioxide, 9.81% calcium oxide, 14.26% aluminum oxide, 6.29% iron oxide, 4.37% magnesium oxide, 5.15% potassium oxide, 3.14% sulfur trioxide, 0.37% sodium oxide, and 2.79% loss on ignition.

[0040] The cement is grade 42.5 low-alkalinity sulfoaluminate cement.

[0041] The apparent density of river sand is 2660-2690 kg / m³ 3 The fineness modulus is 2.3-2.5, the particle size is 0.15-4.75mm, and the mud content is 0.8-1.3%.

[0042] The mineral powder is S95 grade, with an apparent density of 2.8-2.9 g / cm³. 3 Specific surface area is 450-500 m² 2 / kg, moisture content is 0.2-1%, particle size is 20-50μm.

[0043] The basalt gravel has a continuous gradation of 5-25mm and a mud content of 0.1-0.3%.

[0044] The fly ash is Class F, Grade I fly ash, with a fineness of 10-20μm, a loss on ignition of 2.6-2.9%, and a moisture content of 0.1-0.2%.

[0045] The water-reducing agent is a polycarboxylate water-reducing agent, model PCA®-Ⅰ series polycarboxylate high-performance water-reducing agent, purchased from Jiangsu Subote New Material Co., Ltd.

[0046] The epoxy resin is epoxy resin E-51, item number E871957, purchased from Shanghai McLean Biochemical Technology Co., Ltd.

[0047] Sodium carboxymethyl cellulose with a viscosity of 1500-3100 mPa·s, USP, item number C6332, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0048] The silane coupling agent is KH560 (3-glycidoxypropyltrimethoxysilane).

[0049] Example 1

[0050] A high-strength concrete based on the recycling of construction solid waste comprises the following raw materials by weight: 280 parts cement, 300 parts recycled coarse aggregate, 280 parts recycled fine aggregate, 40 parts river sand, 50 parts mineral powder, 55 parts fly ash, 30 parts basalt crushed stone, 20 parts composite red brick powder, 2 parts polycarboxylate superplasticizer, and 130 parts water.

[0051] A process for preparing high-strength concrete based on recycled construction solid waste includes the following preparation steps:

[0052] Cement, recycled coarse aggregate, recycled fine aggregate, river sand, mineral powder, fly ash, basalt crushed stone and composite red brick powder are mixed to form a mixture. Polycarboxylate superplasticizer and water are added to the mixture, and the mixture is stirred at a speed of 80 r / min for 3 min to obtain high-strength concrete.

[0053] Composite red brick powder is prepared by the following steps:

[0054] A1. A 0.04 mol / L calcium chloride aqueous solution and a 0.04 mol / L sodium carbonate ethylene glycol solution were mixed evenly. Red brick powder was added, and the mixture was stirred for adsorption for 30 min. The mixture was then stirred at 1000 r / min and 20 °C for 2 h. After filtration, the mixture was washed three times with ethanol and three times with deionized water. It was dried in an oven at 60 °C for 1 h, placed in a tube furnace, heated to 900 °C at a heating rate of 5 °C / min, and held at that temperature for 4 h. After cooling to room temperature, red brick powder loaded with calcium silicate was obtained. The mass ratio of calcium chloride aqueous solution, sodium carbonate ethylene glycol solution, and red brick powder was 40:40:2.5.

[0055] A2. Mix calcium silicate-loaded red brick powder with a 1% (w / w) sodium carboxymethyl cellulose solution, stir at 60°C for 30 min, remove and dry in a 60°C oven for 10 min, add to ethanol and deionized water, stir evenly, add KH560, stir and react at 70°C for 1 h, filter, wash three times with deionized water, and dry in a 70°C oven for 10 min to obtain modified red brick powder; the mass ratio of calcium silicate-loaded red brick powder, sodium carboxymethyl cellulose solution, ethanol, deionized water and KH560 is 2.2:20:90:30:0.5;

[0056] A3. Epoxy resin E-51 and ethyl acetate were mixed and stirred at 50℃ and 1000 r / min until the epoxy resin was fully dissolved. Dibutyltin dilaurate and dichlorodimethylsilane were added, and the mixture was stirred at 50℃ for 1 h. During the reaction, triethylamine was used to remove the hydrogen chloride generated in the reaction. The mass of triethylamine was 10% of the mass of epoxy resin E-51. After the reaction was completed, the product was collected by centrifugation at 1500 r / min. The product was washed three times with deionized water and then distilled under reduced pressure at -0.08 MPa and 70℃ for 2 h to obtain organosilicon modified epoxy resin. The mass ratio of epoxy resin E-51, ethyl acetate, dibutyltin dilaurate, and dichlorodimethylsilane was 8:10:0.04:0.7.

[0057] A4. Mix organosilicon-modified epoxy resin and acetone, stir evenly, add modified red brick powder and ethylenediamine, stir at 20℃ and 2800r / min for 1h, then raise the temperature to 90℃ and stir for 1h, filter, wash three times with deionized water, and dry in an oven at 100℃ for 20min to obtain composite red brick powder; the mass ratio of organosilicon-modified epoxy resin, ethanol, modified red brick powder and ethylenediamine is 0.4:5:2:0.02.

[0058] Example 2

[0059] A high-strength concrete based on recycled construction solid waste comprises the following raw materials by weight: 300 parts cement, 310 parts recycled coarse aggregate, 290 parts recycled fine aggregate, 45 parts river sand, 55 parts mineral powder, 60 parts fly ash, 35 parts basalt crushed stone, 25 parts composite red brick powder, 2.5 parts polycarboxylate superplasticizer, and 140 parts water.

[0060] A process for preparing high-strength concrete based on recycled construction solid waste includes the following preparation steps:

[0061] Cement, recycled coarse aggregate, recycled fine aggregate, river sand, mineral powder, fly ash, basalt crushed stone and composite red brick powder are mixed to form a mixture. Polycarboxylate superplasticizer and water are added to the mixture, and the mixture is stirred at a speed of 100 r / min for 4 min to obtain high-strength concrete.

[0062] Composite red brick powder is prepared by the following steps:

[0063] A1. A 0.05 mol / L calcium chloride aqueous solution and a 0.05 mol / L sodium carbonate ethylene glycol solution were mixed evenly. Red brick powder was added, and the mixture was stirred for adsorption for 30 min. The mixture was then stirred at 1100 r / min and 23℃ for 2.5 h. After filtration, the mixture was washed three times with ethanol and three times with deionized water. It was dried in an oven at 60℃ for 1 h, placed in a tube furnace, heated to 1000℃ at a heating rate of 8℃ / min, and held at that temperature for 5 h. After cooling to room temperature, red brick powder loaded with calcium silicate was obtained. The mass ratio of calcium chloride aqueous solution, sodium carbonate ethylene glycol solution, and red brick powder was 45:45:2.8.

[0064] A2. Calcium silicate-loaded red brick powder and a 1% (w / w) sodium carboxymethyl cellulose solution were mixed and stirred at 60°C for 30 min. The mixture was then removed and dried in a 60°C oven for 10 min. Ethanol and deionized water were added, and the mixture was stirred until homogeneous. KH560 was added, and the mixture was stirred and reacted at 75°C for 1.5 h. After filtration, the mixture was washed three times with deionized water and dried in a 70°C oven for 10 min to obtain modified red brick powder. The mass ratio of calcium silicate-loaded red brick powder, sodium carboxymethyl cellulose solution, ethanol, deionized water, and KH560 was 2.3:25:95:35:0.6.

[0065] A3. Epoxy resin E-51 and ethyl acetate were mixed and stirred at 50℃ and 1000 r / min until the epoxy resin was fully dissolved. Dibutyltin dilaurate and dichlorodimethylsilane were added, and the mixture was stirred at 53℃ for 1.5 h. During the reaction, triethylamine was used to remove the hydrogen chloride produced in the reaction. The mass of triethylamine was 10% of the mass of epoxy resin E-51. After the reaction was completed, the product was collected by centrifugation at 1500 r / min. The product was washed three times with deionized water and then distilled under reduced pressure at -0.08 MPa and 70℃ for 2 h to obtain organosilicon modified epoxy resin. The mass ratio of epoxy resin E-51, ethyl acetate, dibutyltin dilaurate, and dichlorodimethylsilane was 9:11:0.05:0.75.

[0066] A4. Mix organosilicon-modified epoxy resin and acetone, stir evenly, add modified red brick powder and ethylenediamine, stir at 23℃ and 2900r / min for 1.5h, then raise the temperature to 95℃ and stir for 1.3h, filter, wash three times with deionized water, and dry in an oven at 100℃ for 20min to obtain composite red brick powder; the mass ratio of organosilicon-modified epoxy resin, ethanol, modified red brick powder and ethylenediamine is 0.45:8:2.1:0.03.

[0067] Example 3

[0068] A high-strength concrete based on the recycling of construction solid waste comprises the following raw materials by weight: 320 parts cement, 320 parts recycled coarse aggregate, 300 parts recycled fine aggregate, 50 parts river sand, 60 parts mineral powder, 65 parts fly ash, 40 parts basalt crushed stone, 30 parts composite red brick powder, 3 parts polycarboxylate superplasticizer, and 150 parts water.

[0069] A process for preparing high-strength concrete based on recycled construction solid waste includes the following preparation steps:

[0070] Cement, recycled coarse aggregate, recycled fine aggregate, river sand, mineral powder, fly ash, basalt crushed stone and composite red brick powder are mixed to form a mixture. Polycarboxylate superplasticizer and water are added to the mixture, and the mixture is stirred at a speed of 120 r / min for 5 min to obtain high-strength concrete.

[0071] Composite red brick powder is prepared by the following steps:

[0072] A1. A 0.06 mol / L calcium chloride aqueous solution and a 0.06 mol / L sodium carbonate ethylene glycol solution were mixed evenly. Red brick powder was added, and the mixture was stirred and adsorbed for 30 min. The mixture was then stirred and reacted at 1200 r / min and 25 °C for 3 h. After filtration, the mixture was washed three times with ethanol and three times with deionized water. It was dried in an oven at 60 °C for 1 h, placed in a tube furnace, heated to 1100 °C at a heating rate of 10 °C / min, and held at that temperature for 6 h. After cooling to room temperature, red brick powder loaded with calcium silicate was obtained. The mass ratio of calcium chloride aqueous solution, sodium carbonate ethylene glycol solution, and red brick powder was 50:50:3.

[0073] A2. Mix calcium silicate-loaded red brick powder with a 1% (w / w) sodium carboxymethyl cellulose solution, stir at 60°C for 30 min, remove and dry in a 60°C oven for 10 min, add to ethanol and deionized water, stir evenly, add KH560, stir and react at 80°C for 2 h, filter, wash three times with deionized water, and dry in a 70°C oven for 10 min to obtain modified red brick powder; the mass ratio of calcium silicate-loaded red brick powder, sodium carboxymethyl cellulose solution, ethanol, deionized water and KH560 is 2.5:30:100:40:0.7;

[0074] A3. Epoxy resin E-51 and ethyl acetate were mixed and stirred at 50℃ and 1000 r / min until the epoxy resin was fully dissolved. Dibutyltin dilaurate and dichlorodimethylsilane were added, and the mixture was stirred at 55℃ for 2 h. During the reaction, triethylamine was used to remove the hydrogen chloride produced in the reaction. The mass of triethylamine was 10% of the mass of epoxy resin E-51. After the reaction was completed, the product was collected by centrifugation at 1500 r / min. The product was washed three times with deionized water and then distilled under reduced pressure at -0.08 MPa and 70℃ for 2 h to obtain organosilicon modified epoxy resin. The mass ratio of epoxy resin E-51, ethyl acetate, dibutyltin dilaurate, and dichlorodimethylsilane was 10:12:0.06:0.8.

[0075] A4. Mix organosilicon-modified epoxy resin and acetone, stir evenly, add modified red brick powder and ethylenediamine, stir at 25℃ and 3000r / min for 2h, then raise the temperature to 100℃ and stir for 1.5h, filter, wash three times with deionized water, and dry in an oven at 100℃ for 20min to obtain composite red brick powder; the mass ratio of organosilicon-modified epoxy resin, ethanol, modified red brick powder and ethylenediamine is 0.5:10:2.2:0.04.

[0076] Comparative Example 1

[0077] The only difference between this comparative example and Example 3 is the preparation of the composite red brick powder, as detailed below:

[0078] Composite red brick powder is prepared by the following steps:

[0079] A1. Mix red brick powder and a 1% sodium carboxymethyl cellulose solution, stir at 60℃ for 30 min, remove and dry in a 60℃ oven for 10 min, add to ethanol and deionized water, stir evenly, add KH560, stir and react at 80℃ for 2 h, filter, wash three times with deionized water, and dry in a 70℃ oven for 10 min to obtain modified red brick powder; the mass ratio of red brick powder, sodium carboxymethyl cellulose solution, ethanol, deionized water and KH560 is 2.5:30:100:40:0.7;

[0080] A2. Epoxy resin E-51 and ethyl acetate were mixed and stirred at 50℃ and 1000 r / min until the epoxy resin was fully dissolved. Dibutyltin dilaurate and dichlorodimethylsilane were added, and the mixture was stirred at 55℃ for 2 h. During the reaction, triethylamine was used to remove the hydrogen chloride generated in the reaction. The mass of triethylamine was 10% of the mass of epoxy resin E-51. After the reaction was completed, the product was collected by centrifugation at 1500 r / min. The product was washed three times with deionized water and then distilled under reduced pressure at -0.08 MPa and 70℃ for 2 h to obtain organosilicon modified epoxy resin. The mass ratio of epoxy resin E-51, ethyl acetate, dibutyltin dilaurate, and dichlorodimethylsilane was 10:12:0.06:0.8.

[0081] A3. Mix organosilicon-modified epoxy resin and acetone, stir evenly, add modified red brick powder and ethylenediamine, stir at 25℃ and 3000r / min for 2h, then raise the temperature to 100℃ and stir for 1.5h, filter, wash three times with deionized water, and dry in an oven at 100℃ for 20min to obtain composite red brick powder; the mass ratio of organosilicon-modified epoxy resin, ethanol, modified red brick powder and ethylenediamine is 0.5:10:2.2:0.04.

[0082] Comparative Example 2

[0083] The only difference between this comparative example and Example 3 is the preparation of the composite red brick powder, as detailed below:

[0084] Composite red brick powder is prepared by the following steps:

[0085] A1. A 0.06 mol / L calcium chloride aqueous solution and a 0.06 mol / L sodium carbonate ethylene glycol solution were mixed evenly. Red brick powder was added, and the mixture was stirred and adsorbed for 30 min. The mixture was then stirred and reacted at 1200 r / min and 25 °C for 3 h. After filtration, the mixture was washed three times with ethanol and three times with deionized water. It was dried in an oven at 60 °C for 1 h, placed in a tube furnace, heated to 1100 °C at a heating rate of 10 °C / min, and held at that temperature for 6 h. After cooling to room temperature, red brick powder loaded with calcium silicate was obtained. The mass ratio of calcium chloride aqueous solution, sodium carbonate ethylene glycol solution, and red brick powder was 50:50:3.

[0086] A2. Epoxy resin E-51 and ethyl acetate were mixed and stirred at 50℃ and 1000 r / min until the epoxy resin was fully dissolved. Dibutyltin dilaurate and dichlorodimethylsilane were added, and the mixture was stirred at 55℃ for 2 h. During the reaction, triethylamine was used to remove the hydrogen chloride generated in the reaction. The mass of triethylamine was 10% of the mass of epoxy resin E-51. After the reaction was completed, the product was collected by centrifugation at 1500 r / min. The product was washed three times with deionized water and then distilled under reduced pressure at -0.08 MPa and 70℃ for 2 h to obtain organosilicon modified epoxy resin. The mass ratio of epoxy resin E-51, ethyl acetate, dibutyltin dilaurate, and dichlorodimethylsilane was 10:12:0.06:0.8.

[0087] A3. Mix organosilicon-modified epoxy resin and acetone, stir evenly, add red brick powder loaded with calcium silicate and ethylenediamine, stir at 25℃ and 3000r / min for 2h, then raise the temperature to 100℃ and stir for 1.5h, filter, wash three times with deionized water, and dry in an oven at 100℃ for 20min to obtain composite red brick powder; the mass ratio of organosilicon-modified epoxy resin, ethanol, red brick powder loaded with calcium silicate and ethylenediamine is 0.5:10:2.2:0.04.

[0088] Comparative Example 3

[0089] The only difference between this comparative example and Example 3 is the preparation of the composite red brick powder, as detailed below:

[0090] Composite red brick powder is prepared by the following steps:

[0091] A1. A 0.06 mol / L calcium chloride aqueous solution and a 0.06 mol / L sodium carbonate ethylene glycol solution were mixed evenly. Red brick powder was added, and the mixture was stirred and adsorbed for 30 min. The mixture was then stirred and reacted at 1200 r / min and 25 °C for 3 h. After filtration, the mixture was washed three times with ethanol and three times with deionized water. It was dried in an oven at 60 °C for 1 h, placed in a tube furnace, heated to 1100 °C at a heating rate of 10 °C / min, and held at that temperature for 6 h. After cooling to room temperature, red brick powder loaded with calcium silicate was obtained. The mass ratio of calcium chloride aqueous solution, sodium carbonate ethylene glycol solution, and red brick powder was 50:50:3.

[0092] A2. Mix calcium silicate-loaded red brick powder with a 1% (w / w) sodium carboxymethyl cellulose solution, stir at 60°C for 30 min, remove and dry in a 60°C oven for 10 min, add to ethanol and deionized water, stir evenly, add KH560, stir and react at 80°C for 2 h, filter, wash three times with deionized water, and dry in a 70°C oven for 10 min to obtain modified red brick powder; the mass ratio of calcium silicate-loaded red brick powder, sodium carboxymethyl cellulose solution, ethanol, deionized water and KH560 is 2.5:30:100:40:0.7;

[0093] A3. Mix epoxy resin E-51 and acetone, stir evenly, add modified red brick powder and ethylenediamine, stir at 25℃ and 3000r / min for 2h, then raise the temperature to 100℃ and stir for 1.5h, filter, wash three times with deionized water, and dry in an oven at 100℃ for 20min to obtain composite red brick powder; the mass ratio of organosilicon modified epoxy resin, ethanol, modified red brick powder and ethylenediamine is 0.5:10:2.2:0.04.

[0094] Comparative Example 4

[0095] The only difference between this comparative example and Example 3 is the preparation of the composite red brick powder, as detailed below:

[0096] Composite red brick powder is prepared by the following steps:

[0097] A1. A 0.06 mol / L calcium chloride aqueous solution and a 0.06 mol / L sodium carbonate ethylene glycol solution were mixed evenly. Red brick powder was added, and the mixture was stirred and adsorbed for 30 min. The mixture was then stirred and reacted at 1200 r / min and 25 °C for 3 h. After filtration, the mixture was washed three times with ethanol and three times with deionized water. It was dried in an oven at 60 °C for 1 h, placed in a tube furnace, heated to 1100 °C at a heating rate of 10 °C / min, and held at that temperature for 6 h. After cooling to room temperature, red brick powder loaded with calcium silicate was obtained. The mass ratio of calcium chloride aqueous solution, sodium carbonate ethylene glycol solution, and red brick powder was 50:50:3.

[0098] A2. Mix calcium silicate-loaded red brick powder with a 1% (w / w) sodium carboxymethyl cellulose solution, stir at 60°C for 30 min, remove and dry in a 60°C oven for 10 min, add to ethanol and deionized water, stir evenly, add KH560, stir and react at 80°C for 2 h, filter, wash three times with deionized water, and dry in a 70°C oven for 10 min to obtain modified red brick powder; the mass ratio of calcium silicate-loaded red brick powder, sodium carboxymethyl cellulose solution, ethanol, deionized water and KH560 is 2.5:30:100:40:0.7;

[0099] A3. Epoxy resin E-51 and ethyl acetate were mixed and stirred at 50℃ and 1000 r / min until the epoxy resin was fully dissolved. Dibutyltin dilaurate and dichlorodimethylsilane were added, and the mixture was stirred at 55℃ for 2 h. During the reaction, triethylamine was used to remove the hydrogen chloride produced in the reaction. The mass of triethylamine was 10% of the mass of epoxy resin E-51. After the reaction was completed, the product was collected by centrifugation at 1500 r / min. The product was washed three times with deionized water and then distilled under reduced pressure at -0.08 MPa and 70℃ for 2 h to obtain organosilicon modified epoxy resin. The mass ratio of epoxy resin E-51, ethyl acetate, dibutyltin dilaurate, and dichlorodimethylsilane was 10:12:0.06:0.8.

[0100] A4. Mix organosilicon-modified epoxy resin and acetone, stir evenly, add modified red brick powder, stir at 25℃ and 3000r / min for 2h, then raise the temperature to 100℃ and stir for 1.5h, filter, wash three times with deionized water, and dry in an oven at 100℃ for 20min to obtain composite red brick powder; the mass ratio of organosilicon-modified epoxy resin, ethanol and modified red brick powder is 0.5:10:2.2.

[0101] The performance of the high-strength concrete prepared in Examples 1-3 and Comparative Examples 1-4 was then tested.

[0102] Mechanical performance testing: The 28-day compressive strength and 28-day flexural strength of the high-strength concrete prepared above were tested in accordance with GBT50784-2013 "Technical Standard for On-site Testing of Concrete Structures".

[0103] Water permeability grade: The water permeability grade is determined according to the water permeability test - stepwise pressure method in GB / T50082-2024 "Standard for Test Methods of Long-term Performance and Durability of Concrete"; the unsteady chloride ion migration coefficient (DRCM) of concrete is detected according to the chloride ion penetration test - rapid chloride ion migration coefficient method. For the measured DRCM, the chloride ion penetration grade is evaluated according to the "Standard for Evaluation of Durability of Concrete JGJ / T193-2009".

[0104] As shown in Table 1 below.

[0105] Table 1. Performance testing of high-strength concrete prepared in Examples 1-3 and Comparative Examples 1-4

[0106] project 28-day compressive strength / MPa 28-day flexural strength / MPa Waterproofing grade Chloride ion penetration resistance level Example 1 75.8 10.7 P12 RCM-Ⅳ Example 2 76.1 11.4 P12 RCM-Ⅳ Example 3 74.9 10.2 P12 RCM-Ⅳ Comparative Example 1 58.6 5.4 P8 RCM-II Comparative Example 2 60.1 7.3 P10 RCM-III Comparative Example 3 59.0 6.6 P8 RCM-II Comparative Example 4 57.2 5.1 P8 RCM-II

[0107] As can be seen from the data in Table 1, the high-strength concrete prepared in Examples 1-3 has good mechanical strength and impermeability.

[0108] In Comparative Example 1, replacing the calcium silicate-loaded red brick powder with composite red brick powder prepared from red brick powder and adding it to high-strength concrete resulted in a decrease in its mechanical strength and impermeability. This demonstrates that the calcium silicate synthesized in the pores of red brick powder can fill the pores, reduce the porosity of the red brick powder, and weaken its water absorption capacity. Furthermore, calcium silicate is insoluble in water and has high waterproof performance, forming a waterproof layer in the pores and surface of the red brick powder. This prevents the porous structure of red brick powder from easily absorbing water, which would lead to poor impermeability of the concrete material and affect its mechanical strength. In addition, as a hydration product of cement, calcium silicate, when added to concrete, can significantly improve the compressive strength of the concrete.

[0109] In Comparative Example 2, when the modified red brick powder was replaced with red brick powder loaded with calcium silicate, the composite red brick powder prepared and added to high-strength concrete showed a decrease in mechanical strength and impermeability. This demonstrates that the grafting of silane coupling agent onto the surface of red brick powder loaded with calcium silicate introduces epoxy groups and organosilicon segments onto the surface of the red brick powder. This facilitates the coating of the red brick powder with organosilicon-modified epoxy resin, improves the acid and alkali resistance of the red brick powder, and prevents the calcium silicate in the red brick powder from easily reacting and decomposing with acid under acidic conditions. This prevents the porous structure of the red brick powder from easily absorbing water, damaging the dense structure of the concrete, and reducing the mechanical strength and impermeability of the concrete.

[0110] In Comparative Example 3, when the silicone-modified epoxy resin was replaced with epoxy resin E-51 to prepare composite red brick powder, its mechanical strength and impermeability decreased when added to high-strength concrete. This demonstrates that using dichlorodimethylsilane to graft and modify the epoxy resin weakens the hydrophilic hydroxyl groups on the epoxy resin molecular chain, while introducing hydrophobic methyl groups to improve the hydrophobicity of the epoxy resin. The hydrophobic segments contained in the silicone-modified epoxy resin form a waterproof layer along the capillary pores in the concrete, reducing the penetration of moisture and corrosive media through the capillary pores after the concrete has cured, blocking the penetration of moisture, acidic media, and harmful ions, and improving the impermeability of the concrete. Furthermore, the introduced Si-O and Si-O-Si bonds enable the silicone-modified epoxy resin to effectively absorb and disperse impact forces when subjected to external impacts, thus improving the mechanical strength and impermeability of the concrete.

[0111] In Comparative Example 4, the composite red brick powder prepared without ethylenediamine was added to high-strength concrete, resulting in a decrease in its mechanical strength and impermeability. This demonstrates that the silicone-modified epoxy resin, through ethylenediamine coating on the surface of the modified red brick powder, can prevent acidic media from penetrating into the interior of the modified red brick powder, corroding and dissolving the calcium silicate inside the modified red brick powder, and avoiding the easy decomposition of calcium silicate in the red brick powder under acidic conditions. This prevents the porous structure of the red brick powder from easily absorbing water, thus reducing the mechanical strength and impermeability of the concrete. Furthermore, the silicone-modified epoxy resin on the surface of the composite red brick powder exhibits a cross-linked network structure, allowing the concrete substrate to penetrate into the cross-linked network structure, resulting in the composite red brick powder being uniformly dispersed in the concrete, thereby improving the mechanical strength and impermeability of the concrete.

[0112] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0113] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A high-strength concrete based on recycled construction solid waste, characterized in that, The raw materials include the following parts by weight: 280-320 parts cement, 300-320 parts recycled coarse aggregate, 280-300 parts recycled fine aggregate, 40-50 parts river sand, 50-60 parts mineral powder, 55-65 parts fly ash, 30-40 parts basalt crushed stone, 20-30 parts composite red brick powder, 2-3 parts water-reducing agent, and 130-150 parts water. The composite red brick powder is obtained by grafting dichlorodimethylsilane onto epoxy resin, and then reacting it with modified red brick powder and ethylenediamine. The modified red brick powder is obtained by mixing red brick powder with calcium chloride and sodium carbonate, reacting and calcining, and then surface-treating with a silane coupling agent.

2. The high-strength concrete based on recycled construction solid waste according to claim 1, characterized in that, The composite red brick powder is prepared by the following steps: A1. Mix calcium chloride aqueous solution and sodium carbonate ethylene glycol solution evenly, add red brick powder, stir and adsorb, stir and react at 1000-1200 r / min and 20-25℃ for 2-3 h, filter, wash, dry, place in tube furnace, heat to 900-1100℃ at a heating rate of 5-10℃ / min, keep at the temperature for 4-6 h, cool to room temperature to obtain red brick powder loaded with calcium silicate; A2. Mix red brick powder loaded with calcium silicate and sodium carboxymethyl cellulose solution, stir, remove, dry, then add to ethanol and deionized water, stir evenly, add silane coupling agent, stir reaction at 70-80℃ for 1-2 hours, filter, wash, dry to obtain modified red brick powder; A3. Mix epoxy resin and ethyl acetate and stir until the epoxy resin is fully dissolved. Add dibutyltin dilaurate and dichlorodimethylsilane and stir at 50-55℃ for 1-2 hours. During the reaction, triethylamine is used to remove the hydrogen chloride produced in the reaction. After the reaction is complete, collect the product by centrifugation. After washing the product, perform vacuum distillation to obtain organosilicon modified epoxy resin. A4. Mix organosilicon-modified epoxy resin and acetone, stir evenly, add modified red brick powder and ethylenediamine, stir at 20-25℃ and 2800-3000r / min for 1-2h, then raise the temperature to 90-100℃ and stir for 1-1.5h. After filtration, washing and drying, composite red brick powder is obtained.

3. The high-strength concrete based on recycled construction solid waste according to claim 1, characterized in that, In step A1, the concentration of the calcium chloride aqueous solution is 0.04-0.06 mol / L; the concentration of the sodium carbonate ethylene glycol solution is 0.04-0.06 mol / L; and the mass ratio of the calcium chloride aqueous solution, the sodium carbonate ethylene glycol solution, and the red brick powder is (40-50):(40-50):(2.5-3).

4. The high-strength concrete based on recycled construction solid waste according to claim 1, characterized in that, In step A2, the mass ratio of the calcium silicate-loaded red brick powder, sodium carboxymethyl cellulose solution, ethanol, deionized water, and silane coupling agent is (2.2-2.5):(20-30):(90-100):(30-40):(0.5-0.7).

5. The high-strength concrete based on recycled construction solid waste according to claim 1, characterized in that, In step A3, the mass ratio of epoxy resin, ethyl acetate, dibutyltin dilaurate, and dichlorodimethylsilane is (8-10):(10-12):(0.04-0.06):(0.7-0.8).

6. The high-strength concrete based on recycled construction solid waste according to claim 1, characterized in that, In step A4, the mass ratio of the organosilicon-modified epoxy resin, ethanol, modified red brick powder and ethylenediamine is (0.4-0.5):(5-10):(2-2.2):(0.02-0.04).

7. The high-strength concrete based on recycled construction solid waste according to claim 1, characterized in that, The apparent density of the river sand is 2660-2690 kg / m³. 3 The fineness modulus is 2.3-2.5, the particle size is 0.15-4.75mm, and the mud content is 0.8-1.3%.

8. The high-strength concrete based on recycled construction solid waste according to claim 1, characterized in that, The mineral powder is S95 grade mineral powder with an apparent density of 2.8-2.9 g / cm³. 3 Specific surface area is 450-500 m² 2 / kg, moisture content is 0.2-1%, particle size is 20-50μm; The basalt gravel has a continuous gradation of 5-25mm and a mud content of 0.1-0.3%.

9. A high-strength concrete based on recycled construction solid waste according to claim 1, characterized in that, The fly ash is Class I F fly ash, with a fineness of 10-20 μm, a loss on ignition of 2.6-2.9%, and a moisture content of 0.1-0.2%; the water-reducing agent is a polycarboxylate water-reducing agent.

10. A method for preparing high-strength concrete based on the recycling of construction solid waste as described in any one of claims 1-9, characterized in that, The preparation steps include the following: Cement, recycled coarse aggregate, recycled fine aggregate, river sand, mineral powder, fly ash, basalt crushed stone and composite red brick powder are mixed to form a mixture. Water-reducing agent and water are added to the mixture, and it is mixed and stirred at a rate of 80-120 r / min for 3-5 minutes to obtain high-strength concrete.