Industrial solid waste-based concrete and composite wallboard

Abstract

The present application relates to the technical field of cement-based building materials, and particularly relates to an industrial solid waste-based concrete and a composite wallboard, which utilizes steel slag to replace cement, utilizes zinc slag and fly ash to prepare a silico-aluminate phosphate material, and adjusts the composition of an additive to prepare a basic support heat insulation layer and a fireproof flame-retardant insulation layer by using a 3D printing technology, and a waterproof wear-resistant partition layer is arranged on the outermost layer, so as to prepare a multifunctional gradient composite wallboard with solid waste resource utilization and reduced carbon emission.

Description

Technical Field

[0001] This invention relates to the field of cement-based building materials technology, and in particular to an industrial solid waste-based concrete and composite wall panel. Background Technology

[0002] Due to gas leaks, improper use of electrical appliances, and other reasons, building fires have become one of the most frequent, destructive, and damaging disasters today. The heavy weight and poor fire resistance of the exterior wall panels of high-rise buildings greatly affect the safety of high-rise buildings. Therefore, the demand for exterior wall panels that combine multiple advantages such as lightweight, fire resistance, and crack resistance is increasing day by day.

[0003] Fly ash is a byproduct of pulverized coal combustion in a furnace. Its main chemical components are Al2O3 and SiO2, and it is a major solid waste discharged from coal-fired power plants. Large quantities of fly ash, if left untreated, will generate dust and pollute the atmosphere; if discharged into waterways, it will cause river siltation, and the toxic chemicals within it will also harm human health and other organisms.

[0004] Steel slag is an industrial solid waste generated during steelmaking. Large quantities of steel slag are directly dumped or used for road paving, not only occupying significant land resources but also causing serious pollution of soil and water sources due to the highly alkaline leachates, impacting the natural environment and human health and safety. Therefore, the need for the rational disposal and resource utilization of steel slag is increasingly urgent. Since steel slag and cement have similar mineral compositions, finding a suitable amount of steel slag powder to replace cement and avoid the leaching of alkaline substances from the steel slag is one direction for the resource utilization of steel slag. This can not only improve the utilization rate of steel slag, reduce cement usage, and lower costs, but also reduce CO2 emissions, aligning with the concepts of green environmental protection and sustainable development.

[0005] Ordinary wall panels mixed with steel slag powder have poor crack resistance and fire resistance. Currently available wall panels often fail to meet flame retardant standards, making it difficult to meet construction industry standards and leading to frequent fires and significant losses. Therefore, developing a more efficient, crack-resistant, and fire-resistant multifunctional gradient composite wall panel by rationally utilizing steel slag and aluminosilicate phosphate materials, and employing rapid 3D printing methods for its fabrication, is of great significance for the sustainable development of the industry. Summary of the Invention

[0006] To overcome the problems existing in the prior art, this invention provides an industrial solid waste-based concrete and utilizes it to prepare a multifunctional gradient composite wall panel. Specifically, this invention uses steel slag to replace cement, uses zinc slag and fly ash to prepare a silica-alumina phosphate material, and by adjusting the composition of admixtures, uses 3D printing technology to prepare a basic supporting heat insulation layer and a fire-retardant insulation layer, and sets a waterproof and wear-resistant partition layer on the outermost layer, thereby preparing a multifunctional gradient composite wall panel that utilizes solid waste resources and reduces carbon emissions.

[0007] Specifically, the present invention first relates to an industrial solid waste-based concrete prepared by 3D printing, which is composed of the following raw materials in parts by weight: 5-10 parts of zinc slag, 50-60 parts of fly ash, 20-30 parts of concentrated phosphoric acid, 10-20 parts of water, and 0.5-3 parts of barium chloride. The main hydration product of the industrial solid waste-based concrete of the present invention is silicoaluminophosphate, and its chemical formula can be abbreviated as (Si x Al y P z )O2, where x is the molar fraction of Si: 0.07 < x ≤ 0.2, y is the molar fraction of Al: 0.37 ≤ y ≤ 0.55, z is the molar fraction of P: 0.35 ≤ z ≤ 0.48, and x + y + z = 1. The present invention uses zinc slag and fly ash as active substances, and under the excitation condition of concentrated phosphoric acid, a matrix with a three-dimensional network structure is formed through depolymerization-condensation reaction. Compared with traditional Portland cement, the CO2 emissions of silicoaluminophosphate materials are reduced by about 80%, and at the same time, it has good bonding properties, high-temperature resistance, excellent compressive strength, low density, and light weight, etc.

[0008] Preferably, the mass fraction of the concentrated phosphoric acid is 85%.

[0009] The present invention also relates to a composite wallboard. Specifically, it includes a basic support heat insulation layer, a fireproof and flame-retardant isolation layer, and a waterproof and wear-resistant isolation layer arranged in sequence from the inside to the outside. The fireproof and flame-retardant isolation layer is formed by 3D printing the aforementioned industrial solid waste-based concrete. The present invention prints the silicoaluminophosphate material on the surface of the basic support heat insulation layer through 3D printing technology, so that the composite wallboard has an excellent fireproof layer, effectively reducing the damage of high temperature to the basic support heat insulation layer.

[0010] Preferably, the basic support heat insulation layer is formed by uniformly mixing solid materials and water in a weight ratio of 1:0.15-0.25 through 3D printing. The solid materials are composed of the following raw materials in parts by weight: 5-15 parts of steel slag powder, 30-45 parts of cement, 45-60 parts of natural river sand, 0.08-0.3 parts of basalt fiber, 0.4-0.6 parts of water reducing agent, 0.8-3 parts of alkaline activator, 1.2-3 parts of polyacrylamide, and 0.16-1.3 parts of barium chloride.

[0011] Preferably, the composition of the steel slag powder is: 10-20% of steel slag with a particle size of 0.01-0.02mm, 55-70% of steel slag with a particle size of 0.02-0.03mm, and 20-25% of steel slag with a particle size of 0.03-0.06mm.

[0012] This invention demonstrates that steel slag powder has relatively weak activity. If used in large quantities, cement hydration will be inhibited, thereby reducing the performance of cement products. However, by replacing cement with an appropriate amount of steel slag powder as a cementitious material, the density can be increased to a certain extent, and the effective water-cement ratio can be reduced. This not only does not reduce the performance of cement products, but also improves their compressive strength, flexural strength, carbonation resistance, wear resistance, and frost resistance.

[0013] Basalt fiber possesses excellent corrosion resistance, high temperature resistance, and high tensile strength. Through numerous experiments, this invention has found that when the fiber length is short, it cannot function effectively in the specimen; during mechanical property testing, the fiber is not broken by tension or compression, but rather pulled directly out of the specimen. When the fiber length is 6-12mm, the compressive strength and crack resistance of the specimen are improved, mitigating brittleness while effectively reducing or avoiding nozzle clogging problems during 3D printing caused by longer fibers. This invention has conducted extensive experiments on the ratio of steel slag to basalt fiber, continuously adjusting and optimizing the formula to prepare a high-performance composite wall panel's basic support and insulation layer. This effectively expands the application field of steel slag, an industrial waste, reduces cement usage, aligns with the concept of green environmental protection, and reduces carbon emissions.

[0014] The addition of an appropriate amount of polyacrylamide in this invention is beneficial to improving the workability of the slurry. This is because the macromolecules of polyacrylamide exert a surface-active effect on the surface of steel slag powder, and the incorporation of polyacrylamide introduces some air, thereby improving the fluidity of the slurry to a certain extent. After partial hydrolysis, polyacrylamide produces carboxyl groups, which undergo a complexation reaction with calcium ions, thereby reducing the concentration of calcium ions in the pore solution, thus delaying the formation of Ca(OH)2 and CSH gel, slowing down the setting of the slurry, prolonging the initial setting time, and promoting the hydration of steel slag powder and cement. At the same time, an appropriate amount of polyacrylamide microgel can fill the pores in the matrix, thereby improving the carbonation resistance of concrete.

[0015] This invention adds a portion of barium chloride to the basic support insulation layer and the fireproof and flame-retardant barrier layer, which can improve the 3D printing performance of the slurry, optimize the setting time, make the slurry easier to form, and make the microstructure of the obtained specimen sample more compact, thereby improving the compressive strength.

[0016] Preferably, the basalt fibers have a length of 6-12 mm, a melting point of 1400-1550℃, a tensile strength of 3900-4300 MPa, an elastic modulus of 96-102 GPa, an elongation at break of 2.4-2.9%, and a density of 2.8-3.3 g / cm³. 3 .

[0017] Preferably, the water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent.

[0018] Preferably, the alkaline activator is at least one of sodium hydroxide and calcium hydroxide.

[0019] Preferably, the barium chloride is in powder form and has an analytical purity.

[0020] Preferably, the polyacrylamide is a white crystalline solid with a solid content of 97.9% and a density of 1.302 g / cm³. 3 The degree of hydrolysis is 30%.

[0021] Preferably, the waterproof and wear-resistant partition layer is made of a material with a thickness of 1.5 mm and a density of 600 g / m³. 2 Polyethylene-polypropylene waterproof membrane is a composite waterproof material mainly made of non-woven fabric and polyethylene as the main raw materials, with added additives to improve its performance. It consists of four layers: a reinforcing protective layer, an anti-aging layer, a waterproof layer, and an adhesive reinforcing layer. The most prominent feature of polyethylene-polypropylene waterproof membrane is its rough and uniform surface, making it easy to bond to various substrate materials. It can be directly bonded to cement during the curing process, with a peel strength of 130-170 kPa, a property not found in other waterproof materials. Extensive testing has shown that using polyethylene-polypropylene waterproof membrane as a waterproof and wear-resistant partition layer effectively waterproofs while reducing wall panel cracking and increasing the tensile strength of the wall panels.

[0022] This invention also relates to a method for preparing the above-mentioned composite wall panel, specifically comprising the following steps:

[0023] 1) Mix steel slag powder, cement, and natural river sand evenly, add basalt fiber in batches and mix evenly, add a solution of water and water-reducing agent, then add polyacrylamide and barium chloride to obtain the slurry for the basic supporting insulation layer.

[0024] 2) Grind fly ash into a ball mill, add zinc slag, stir evenly, add a solution of concentrated phosphoric acid and water, stir evenly, add barium chloride and stir evenly to obtain a slurry for a fireproof and flame-retardant insulating layer.

[0025] 3) Apply a release agent to the mold, add the slurry of the basic support insulation layer and the fire-retardant barrier layer to the 3D printing equipment, set the 3D printing parameters, print the slurry of the basic support insulation layer in the mold, then print the slurry of the fire-retardant barrier layer on the surface of the basic support insulation layer, and finally lay the waterproof and wear-resistant barrier layer flat on the surface of the fire-retardant barrier layer.

[0026] 4) After all the materials in the mold have solidified and hardened, demold to obtain the composite wall panel blank.

[0027] 5) Curing the composite wall panel blanks yields the final product.

[0028] Preferably, in step 1), basalt fibers are added in equal amounts in three separate steps.

[0029] Preferably, the stirring speed in step 1) is 60-120 rpm.

[0030] Preferably, in step 2), the ball-to-material ratio is 1:2, the ball milling frequency is 200-270Hz, and the fly ash is ball milled for 1-1.5 hours.

[0031] Preferably, the stirring speed in step 2) is 60-120 rpm.

[0032] Preferably, the mold size in step 3) is 500×700×55mm, wherein the basic support insulation layer is 50mm, the fireproof and flame-retardant insulation layer is 3.5mm, and the waterproof and wear-resistant partition layer is 1.5mm.

[0033] Preferably, step 4) involves curing in a constant temperature and humidity chamber at 60°C and 70% relative humidity for 1 day.

[0034] Preferably, step 5) curing involves sealing the green body with plastic wrap and curing it in a 30°C drying oven for 6 days, then transferring it to a standard curing room with a temperature of 20±2°C and a relative humidity of over 95% for 28 days.

[0035] Compared with existing technologies, the multifunctional gradient environmentally friendly composite wall panel provided by this invention has the following advantages:

[0036] (1) The basic support insulation layer of the wall panel of the present invention uses cement as the main raw material, and adds appropriate amounts of steel slag micro powder of different grades and appropriate amounts of basalt fiber to solve the problems of low strength and easy cracking of cementitious materials with steel slag alone; it improves the utilization rate of steel slag solid waste, avoids the leaching of high alkaline substances in steel slag solid waste, and has a great promoting effect on the protection of the ecological environment. The fireproof and flame-retardant insulation layer uses zinc slag and fly ash as the main raw materials, reducing costs and making use of waste. The composition of admixtures is adjusted during the preparation of the wall panel, and 3D printing technology is used to improve the level of industrialization.

[0037] (2) Most of the current concrete wall panels are glass fiber reinforced concrete panels. There are problems such as glass fiber not being alkali resistant and glass fiber being exposed to air for a long time, which greatly reduces the strength and toughness of the concrete and affects the strength. This invention effectively solves this problem and has good toughness and crack resistance. Cracks are not easy to generate and develop during use.

[0038] (3) This invention features high strength, crack resistance, good wear and corrosion resistance, high fire resistance, excellent waterproof performance, and the ability to prepare irregularly shaped components. It can effectively expand the application fields of steel slag solid waste, improve the resource utilization rate of steel slag solid waste, and reduce carbon emissions. Detailed Implementation

[0039] To characterize the technical effects of this invention, composite wall panels were prepared and their performance was tested. The panels consist of a 50mm basic supporting insulation layer, a 3.5mm fire-retardant insulating layer, and a 1.5mm waterproof and wear-resistant partition layer. The steel slag powder composition is: 15% 0.01-0.02mm steel slag, 65% 0.02-0.03mm steel slag, and 20% 0.03-0.06mm steel slag. The basalt fiber length is 6-12mm, and P·O42.5 cement is used.

[0040] Example 1

[0041] The ratio of solid material to water in the basic support insulation layer is 1:0.2. The solid material consists of the following raw materials by weight: 8 parts steel slag powder, 40 parts cement, 55 parts natural river sand, 0.2 parts basalt fiber, 0.5 parts polycarboxylate-based high-efficiency water-reducing agent, 3 parts sodium hydroxide, 2 parts polyacrylamide, and 0.8 parts barium chloride.

[0042] The fireproof and flame-retardant insulation layer is composed of the following raw materials in parts by weight: 8 parts zinc slag, 60 parts fly ash, 27 parts concentrated phosphoric acid, 16 parts water, and 2 parts barium chloride.

[0043] The waterproof and wear-resistant partition layer is made of material with a thickness of 1.5mm and a density of 600g / m³. 2 It is composed of polyethylene polypropylene waterproof membrane.

[0044] Testing showed that the basic support insulation layer and fireproof and flame-retardant insulation layer were printed and formed well without collapsing. The composite wall panel had a 28-day compressive strength of 55.3 MPa and a flexural strength of 5.7 MPa.

[0045] Example 2

[0046] The ratio of solid material to water in the basic support insulation layer is 1:0.2. The solid material consists of the following raw materials in parts by weight: 12 parts steel slag powder, 38 parts cement, 55 parts natural river sand, 0.18 parts basalt fiber, 0.5 parts polycarboxylate-based high-efficiency water-reducing agent, 2.4 parts sodium hydroxide, 2.3 parts polyacrylamide, and 1 part barium chloride.

[0047] The fireproof and flame-retardant insulation layer is composed of the following raw materials in parts by weight: 10 parts zinc slag, 58 parts fly ash, 28 parts concentrated phosphoric acid, 15 parts water, and 2 parts barium chloride.

[0048] The waterproof and wear-resistant partition layer is made of material with a thickness of 1.5mm and a density of 600g / m³. 2 It is composed of polyethylene polypropylene waterproof membrane.

[0049] Testing showed that the basic support insulation layer and fireproof and flame-retardant insulation layer were printed and formed well without collapsing. The composite wall panel had a 28-day compressive strength of 52.7 MPa and a flexural strength of 5.5 MPa.

[0050] Comparative Example 1

[0051] The ratio of solid material to water in the basic support insulation layer is 1:0.2. The solid material consists of the following raw materials by weight: 8 parts fly ash, 40 parts cement, 55 parts natural river sand, 0.2 parts polypropylene fiber, 0.5 parts polycarboxylate-based high-efficiency water-reducing agent, 3 parts sodium hydroxide, 2 parts polyacrylamide, and 0.8 parts barium chloride.

[0052] The fireproof and flame-retardant insulation layer is composed of the following raw materials in parts by weight: 68 parts fly ash, 27 parts concentrated phosphoric acid, 16 parts water, and 2 parts barium chloride.

[0053] The waterproof and wear-resistant partition layer is made of material with a thickness of 1.5mm and a density of 600g / m³. 2 It is composed of polyethylene polypropylene waterproof membrane.

[0054] Testing revealed that the basic support insulation layer and fire-retardant barrier layer had poor printing quality, and part of the protective barrier layer had sunk into the basic support insulation layer. The composite wall panel had a 28-day compressive strength of 34.7 MPa and a flexural strength of 2.9 MPa.

[0055] Comparative Example 2

[0056] The ratio of solid material to water in the basic support insulation layer is 1:0.2. The solid material consists of the following raw materials by weight: 8 parts steel slag powder, 40 parts cement, 55 parts natural river sand, 0.2 parts basalt fiber, 0.5 parts polycarboxylate-based high-efficiency water-reducing agent, 3 parts sodium hydroxide, and 2.8 parts polyacrylamide.

[0057] The fireproof and flame-retardant insulation layer is composed of the following raw materials in parts by weight: 10 parts zinc slag, 60 parts fly ash, 27 parts concentrated phosphoric acid, and 16 parts water.

[0058] The waterproof and wear-resistant partition layer is made of material with a thickness of 1.5mm and a density of 600g / m³. 2 It is composed of polyethylene polypropylene waterproof membrane.

[0059] Testing revealed that the 3D printing of the basic support insulation layer and the fireproof and flame-retardant barrier layer was poor and could not be formed.

[0060] Comparative Example 3

[0061] The ratio of solid material to water in the basic support insulation layer is 1:0.2. The solid material consists of the following raw materials by weight: 8 parts steel slag powder, 40 parts cement, 55 parts natural river sand, 0.2 parts 3-5mm basalt fiber, 0.5 parts polycarboxylate-based high-efficiency water-reducing agent, 3 parts sodium hydroxide, and 2.8 parts barium chloride.

[0062] The fireproof and flame-retardant insulation layer is composed of the following raw materials in parts by weight: 68 parts zinc slag, 27 parts concentrated phosphoric acid, 16 parts water, and 2 parts barium chloride.

[0063] The waterproof and wear-resistant partition layer is made of material with a thickness of 1.5mm and a density of 600g / m³. 2 It is composed of polyethylene polypropylene waterproof membrane.

[0064] Testing revealed that the basic support insulation layer and fire-retardant barrier layer had poor printing and molding effects, the basic support insulation layer had a long setting time, the fire-retardant barrier layer had poor extrusion performance, and the composite wall panel had a 28-day compressive strength of 37.2 MPa and a flexural strength of 2.5 MPa.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite wall panel, characterized in that, The system comprises, from the inside out, a basic support and heat insulation layer, a fire-retardant insulation layer, and a waterproof and wear-resistant partition layer. The fire-retardant insulation layer is 3D printed from industrial solid waste-based concrete. This industrial solid waste-based concrete consists of the following raw materials by weight: 5-10 parts zinc slag, 50-60 parts fly ash, 20-30 parts concentrated phosphoric acid, 10-20 parts water, and 0.5-3 parts barium chloride; the concentrated phosphoric acid has a mass fraction of 85%. The basic support insulation layer is formed by 3D printing of a uniform mixture of solid material and water at a weight ratio of 1:0.15-0.

25. The solid material consists of the following raw materials in parts by weight: 5-15 parts steel slag powder, 30-45 parts cement, 45-60 parts natural river sand, 0.08-0.3 parts basalt fiber, 0.4-0.6 parts water-reducing agent, 0.8-3 parts alkaline activator, 1.2-3 parts polyacrylamide, and 0.16-1.3 parts barium chloride. The basalt fiber has a length of 6-12 mm.

2. The composite wall panel according to claim 1, characterized in that, The steel slag powder composition is as follows: 10-20% 0.01-0.02mm steel slag, 55-70% 0.02-0.03mm steel slag, and 20-25% 0.03-0.06mm steel slag.

3. The composite wall panel according to claim 2, characterized in that, The basalt fiber has a melting point of 1400-1550℃, a tensile strength of 3900-4300MPa, an elastic modulus of 96-102GPa, an elongation at break of 2.4-2.9%, and a density of 2.8-3.3g / cm³. 3 .

4. The composite wall panel according to claim 3, characterized in that, The water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent.

5. The composite wall panel according to claim 4, characterized in that, The alkaline activator is at least one of sodium hydroxide and calcium hydroxide.

6. The composite wall panel according to claim 5, characterized in that, The waterproof and wear-resistant partition layer is 1.5mm thick and has a density of 600g / m³. 2 It is composed of polyethylene polypropylene waterproof membrane.

7. The method for preparing the composite wall panel according to any one of claims 1-6, characterized in that, Includes the following steps: 1) Mix steel slag powder, cement, and natural river sand evenly, add basalt fiber in batches and mix evenly, add a solution of water and water-reducing agent, then add polyacrylamide and barium chloride to obtain the slurry for the basic supporting insulation layer. 2) Grind fly ash into a ball mill, add zinc slag, stir evenly, add a solution of concentrated phosphoric acid and water, stir evenly, add barium chloride and stir evenly to obtain a slurry for a fireproof and flame-retardant insulating layer. 3) Apply a release agent to the mold, add the slurry of the basic support insulation layer and the fire-retardant barrier layer to the 3D printing equipment, set the 3D printing parameters, print the slurry of the basic support insulation layer in the mold, then print the slurry of the fire-retardant barrier layer on the surface of the basic support insulation layer, and finally lay the waterproof and wear-resistant barrier layer flat on the surface of the fire-retardant barrier layer. 4) After all the materials in the mold have solidified and hardened, demold to obtain the composite wall panel blank. 5) Curing the composite wall panel blanks yields the final product.