Method for preparing high-strength lightweight aggregate concrete from multi-element solid waste
By combining multiple solid wastes and designing specific gradations, the problem of low industrial solid waste replacement rate was solved, the mechanical and construction properties of concrete were improved, and high-strength lightweight aggregate concrete was prepared, which is suitable for high-rise buildings and other fields.
Patent Information
- Application Number
- CN202511109622.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-08
- Publication Date
- 2025-11-14
AI Technical Summary
In existing technologies, the replacement rate of concrete aggregates with industrial solid waste is low, and the mechanical and construction properties of the resulting concrete cannot meet the high-strength requirements of high-rise buildings.
A multi-component solid waste combination is adopted, including solid waste-based sulfoaluminate cement, crushed stone, blast furnace slag, waste ceramic powder, waste concrete powder and steel slag, etc. Through specific gradation design and cementing system, a composite structure is formed, which improves the density and interfacial bonding performance of concrete, inhibits active components, reduces water absorption, and improves early strength and workability.
It significantly improves the mechanical and workability of concrete, increases the solid waste replacement rate, reduces resource consumption and environmental pollution, and has a simple preparation process, low cost, and is suitable for widespread promotion.
Smart Images
Figure BDA0005539468880000081
Abstract
Description
Technical Field
[0001] This invention belongs to the field of building materials technology, and more specifically relates to a method for preparing high-strength lightweight aggregate concrete from multiple solid wastes. Background Technology
[0002] In the construction industry, concrete is one of the most widely used building materials, and its performance directly affects the durability and safety of engineering structures. Traditional concrete mainly relies on natural aggregates (such as crushed stone and river sand) as coarse and fine aggregates, and uses silicate cement as a binder. However, with the rapid development of the global construction industry, the mining of natural aggregates has led to severe resource depletion and ecological damage. Furthermore, industries such as metallurgy, ceramics, and construction generate a large amount of solid waste annually. Currently, the comprehensive utilization rate of this solid waste is less than 30%, and most of it is still disposed of through stockpiling or landfilling. This not only occupies land but may also cause heavy metal ions to seep into groundwater due to rainwater runoff, resulting in long-term environmental pollution.
[0003] To alleviate resource pressure, researchers have attempted to use industrial solid waste to replace natural aggregates in concrete preparation, but the following technical challenges remain: (1) Insufficient mechanical properties: The aggregates after crushing construction waste contain a large number of microcracks and pores, which significantly reduces the strength of the concrete. Moreover, the surface of the solid waste aggregates is smooth, resulting in low bonding strength with cement paste, which easily leads to interfacial peeling under stress, causing a decrease in the strength of the prepared concrete. (2) Poor workability: The water absorption rate of recycled aggregates is much higher than that of natural aggregates, resulting in poor workability of the concrete, which is prone to bleeding and segregation. In addition, the free CaO and other active components in the solid waste are prone to volume expansion, leading to cracking of the concrete in the later stage. (3) Limited solid waste dosage: Existing studies have confirmed that when the solid waste replacement rate exceeds 50%, the 28-day compressive strength of the concrete is generally lower than 40 MPa, which is difficult to meet the high strength requirements of high-rise buildings, bridges, etc. Therefore, how to overcome the above contradictions and develop a multi-element solid waste-based high-strength lightweight aggregate concrete with a high industrial solid waste replacement rate and excellent mechanical and workability properties has become an urgent need in this field. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing high-strength lightweight aggregate concrete from multiple solid wastes, in order to solve the problems of low aggregate replacement rate and failure of the mechanical and construction properties of the resulting concrete in existing technical solutions that use construction waste or industrial solid waste to replace concrete aggregates.
[0005] To achieve the above objectives, the present invention provides the following solution:
[0006] One of the technical solutions of this invention is to provide a multi-component solid waste-based high-strength lightweight aggregate concrete, comprising the following components in parts by weight: 50-85 parts of solid waste-based sulfoaluminate cement, 10-30 parts of crushed stone, 40-70 parts of blast furnace slag, 30-55 parts of waste ceramic powder, 8-15 parts of sand, 25-30 parts of waste concrete powder, 35-40 parts of steel slag, 1-3 parts of silica fume, 1-2 parts of additives, and 80-90 parts of water.
[0007] Preferably, the solid waste-based sulfoaluminate cement is prepared by means of the following raw materials: 40-60 parts of bauxite tailings, 20-30 parts of fly ash, 10-15 parts of desulfurized gypsum, 5-10 parts of carbide slag, and 0.5-2 parts of flux.
[0008] Preferably, the preparation steps of the solid waste-based sulfoaluminate cement include:
[0009] Bauxite tailings, fly ash, desulfurized gypsum, and carbide slag are mixed in proportion, and flux is added. The mixture is then calcined at 1250–1350℃ for 30–60 minutes, rapidly cooled to below 200℃, and then desulfurized gypsum is added and mixed to obtain solid waste-based sulfoaluminate cement.
[0010] Preferably, the particle size of the blast furnace slag is 5-20 mm; the particle size of the waste ceramic powder is 10-15 mm; the particle size of the waste concrete powder is 1-1.5 mm; and the particle size of the steel slag is 1-2.5 mm.
[0011] Preferably, the steel slag is further subjected to saturated steam treatment at 0.8–1.2 MPa for 6–8 hours before use.
[0012] Preferably, the gradation composition and mass percentage of the crushed stone are: 10-20% crushed stone with a particle size <4.75mm, 40-50% crushed stone with a particle size of 4.75-12mm, and 30-40% crushed stone with a particle size of 12-19mm.
[0013] Preferably, the fineness modulus of the sand is 1.6 to 2.2; the additives and their dosages are: 0.5 to 1 part of defoamer, 0.2 to 0.5 parts of dispersant, and 0.3 to 0.5 parts of water-reducing agent.
[0014] Preferably, the dispersant is triethylhexylphosphoric acid and / or polyacrylamide; the defoamer includes organosilicon defoamers; and the water-reducing agent includes lignin sulfonate water-reducing agents.
[0015] The second technical solution of the present invention provides a method for preparing high-strength lightweight aggregate concrete from the above-mentioned multi-element solid waste, comprising the following steps:
[0016] Solid waste-based sulfoaluminate cement, crushed stone, blast furnace slag, waste ceramic powder, sand, waste concrete powder, steel slag, silica fume, additives and water are mixed, then poured and vibrated in sequence, and finally cured to obtain high-strength lightweight aggregate concrete prepared from multi-element solid waste.
[0017] Preferably, the vibration is performed 5 to 8 times.
[0018] Preferably, the curing temperature is 10–30°C, the curing time is 28–30 days, and the relative humidity is 90–95%.
[0019] The technical mechanism of this invention is as follows:
[0020] Regarding improvements in mechanical properties:
[0021] (1) Multi-scale solid waste gradation design significantly improves the density and interfacial bonding performance of concrete. Using blast furnace slag and waste ceramic powder as the coarse aggregate system, the blast furnace slag has a porous structure and high porosity, providing filling space for the fine aggregate; the waste ceramic powder has high hardness, serving as a skeleton to enhance overall strength. The two form a composite structure of rigid skeleton and elastic buffer, significantly improving compressive strength. Using waste concrete powder and steel slag as the fine aggregate system, the waste concrete powder fills the pores of the coarse aggregate, effectively reducing porosity; the steel slag contains active CaO and Fe2O3, which hydrate with solid waste-based sulfoaluminate cement to generate CSH gel and iron-phase minerals, thus improving interfacial bonding strength.
[0022] (2) By strengthening the concrete with a specific cementitious system, using solid waste-based sulfoaluminate cement as the core, the mechanical strength of the concrete is significantly improved. This invention increases the proportion of C4A3S phase in the solid waste-based sulfoaluminate cement prepared by calcining bauxite tailings / carbide slag at 1250–1350℃, thereby improving the concrete strength. In addition, nano-silica powder fills the nanoscale pores, reducing the proportion of harmful pores and also effectively improving the concrete strength.
[0023] Regarding improvements in construction performance:
[0024] (1) By controlling the pore size, the water absorption rate of concrete is reduced and the durability of concrete is improved. The large pores of the coarse aggregate composed of blast furnace slag and waste ceramic powder are filled by the small and medium pores of the fine aggregate composed of waste concrete powder and steel slag. Combined with the filling of nanoscale pores by nano-silica powder, a three-level pore size gradient is formed, which effectively reduces the water absorption rate and improves the durability of concrete.
[0025] (2) Improve the stability of concrete by inhibiting the active components in solid waste.
[0026] Steel slag undergoes steam aging pretreatment, which hydrates free CaO into Ca(OH)2 in advance. Waste concrete powder, rich in SiO2 and Al2O3, reacts with Ca(OH)2 in a pozzolanic reaction to form CSH gel, further immobilizing Ca. 2+ Furthermore, nano-sized SiO2 particles fill the micropores of cement stone, hindering the contact between moisture and residual active components and inhibiting delayed expansion. Calcium sulfoaluminate (C4A3S) and dicalcium silicate (β-C2S) generated from the preparation of solid waste-based sulfoaluminate cement using raw materials such as calcined bauxite tailings and carbide slag can preferentially consume free CaO, reducing the risk of subsequent hydration and expansion.
[0027] The present invention discloses the following technical effects:
[0028] (1) This invention uses blast furnace slag and waste ceramic powder as coarse aggregates, and waste concrete powder and steel slag as fine aggregates, which are added to the high-strength lightweight aggregate concrete prepared by the multi-element solid waste. This can greatly reduce the amount of crushed stone and sand added, thereby increasing the replacement rate of solid waste and saving resources. Moreover, the waste concrete powder and steel slag of this invention can enter the rich pore structure of blast furnace slag and waste ceramic powder, which improves the mechanical properties and construction performance of the high-strength lightweight aggregate concrete prepared by the multi-element solid waste. At the same time, the large amount of solid waste used reduces the pollution of solid waste to the environment.
[0029] (2) This invention prepares solid waste-based sulfoaluminate cement by calcining bauxite tailings, carbide slag and other raw materials, which effectively improves the early strength and workability of concrete.
[0030] (3) The preparation process of high-strength lightweight aggregate concrete made from multi-element solid waste described in this invention is simple, requires low raw material costs, does not require large-scale equipment, and is suitable for widespread application. Detailed Implementation
[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0032] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0034] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0035] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0036] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.
[0037] Unless otherwise specified, all raw materials used in this invention are commercially available products or waste materials obtained from local solid waste treatment plants.
[0038] The preparation steps of the solid waste-based sulfoaluminate cement are as follows: Prepare 50 parts of bauxite tailings, 25 parts of fly ash, 12 parts of desulfurized gypsum, 8 parts of carbide slag and 1 part of fluorite.
[0039] Bauxite tailings, fly ash, desulfurized gypsum, and carbide slag are mixed in proportion, and fluorite is added to the mixture. The mixture is then calcined at 1250℃ for 60 minutes, removed, and rapidly cooled to below 200℃ using air cooling. Finally, desulfurized gypsum is added and mixed to obtain solid waste-based sulfoaluminate cement.
[0040] The steel slag used was treated with saturated steam at 1 MPa for 6 hours.
[0041] The gradation and dosage of the crushed stone used are as follows: 8 parts crushed stone with a particle size <4.75mm, 12 parts crushed stone with a particle size of 4.75-12mm, and 12 parts crushed stone with a particle size of 12-19mm.
[0042] The blast furnace slag used is dried, ground, and sieved blast furnace slag with a particle size of 15mm.
[0043] The fineness modulus of the sand used is 1.6 to 2.2.
[0044] The particle size of the waste concrete powder used is 1.5mm.
[0045] The particle size of the steel slag used is 2.5 mm.
[0046] Unless otherwise specified, all quantities in this invention are by weight, and all water used is tap water.
[0047] Example 1
[0048] The high-strength lightweight aggregate concrete prepared from multi-component solid waste described in this embodiment comprises the following components in parts by weight: 65 parts solid waste-based sulfoaluminate cement, 30 parts crushed stone, 50 parts blast furnace slag, 45 parts waste ceramic powder, 8 parts sand, 25 parts waste concrete powder, 35 parts steel slag, 1 part silica fume, 1 part dimethyl silicone oil defoamer, 0.5 parts polyacrylamide, 0.5 parts lignin sulfonate water-reducing agent, and 85 parts water.
[0049] Preparation process: Mix the above-mentioned raw materials in parts by weight, then pour them into a mold, and then vibrate 5 times with an interval of 3 seconds between two adjacent vibrations, each vibration lasting 10 seconds. Finally, cure for 28 days at a temperature of 10℃ and a relative humidity of 90% to obtain concrete.
[0050] Example 2
[0051] The high-strength lightweight aggregate concrete prepared from multi-component solid waste described in this embodiment comprises the following components in parts by weight: 85 parts of solid waste-based sulfoaluminate cement, 20 parts of crushed stone, 60 parts of blast furnace slag, 45 parts of waste ceramic powder, 8 parts of sand, 30 parts of waste concrete powder, 35 parts of steel slag, 1 part of silica fume, 1 part of dimethyl silicone oil defoamer, 0.5 parts of triethylhexyl phosphoric acid, 0.5 parts of lignin sulfonate water-reducing agent, and 85 parts of water;
[0052] Preparation process: Mix the above-mentioned raw materials in parts by weight, then pour them into a mold, and then vibrate 7 times with an interval of 4 seconds between two adjacent vibrations, each vibration lasting 15 seconds. Finally, cure for 29 days at a temperature of 15℃ and a relative humidity of 95% to obtain concrete.
[0053] Comparative Example 1
[0054] The solid waste-based sulfoaluminate cement in Example 1 was replaced with an equal mass of ordinary silicate cement, and everything else remained the same as in Example 1.
[0055] Comparative Example 2
[0056] The blast furnace slag and waste ceramic powder of Example 1 were replaced with crushed stone of equal mass and with the same gradation as described in Example 1, and everything else was the same as in Example 1.
[0057] Comparative Example 3
[0058] The waste concrete powder and steel slag in Example 1 were replaced with sand of equal mass, and everything else was the same as in Example 1.
[0059] Comparative Example 4
[0060] Compared with Example 1, the addition of silicon micropowder is omitted, and everything else is the same as in Example 1.
[0061] Comparative Example 5
[0062] Compared to Example 1, steel slag that has not undergone saturated steam treatment was used, while other aspects remained the same as in Example 1.
[0063] The compressive strength, splitting tensile strength, and water absorption of the concrete obtained in Examples 1-2 and Comparative Examples 1-5 were tested.
[0064] The testing method is as follows:
[0065] Compressive strength and splitting tensile strength tests: The concrete obtained in Examples 1-2 and Comparative Examples 1-5 were cured with the formwork for 1 day, then the formwork was removed, and the concrete was placed in a standard curing room for 28 days. The compressive strength and splitting tensile strength were then tested, and the test results are shown in Table 1.
[0066] Water absorption test: Except for the water-absorbing surface, the concrete obtained in Examples 1-2 and Comparative Examples 1-5 were sealed with paraffin wax. The mass of each concrete sample after being sealed with paraffin wax was measured and recorded as m. Then, the samples were soaked in water for 24 hours and taken out to measure the mass, which was recorded as m1. The test results are shown in Table 1.
[0067] Table 1. Test results of compressive strength, splitting tensile strength, and water absorption of the concrete obtained in Examples 1-2 and Comparative Examples 1-5.
[0068]
[0069] As shown in Table 1, the strength of Comparative Example 1 (ordinary Portland cement) decreased by nearly 30% compared to the Example. This is due to the lack of the C4A3S early-strength phase and poor interfacial compatibility with solid waste aggregate, resulting in a significant reduction in concrete strength. The strength of Comparative Example 5 (untreated steel slag) decreased by nearly 12% compared to the Example. This is due to the later expansion of free CaO leading to microcracks, affecting the mechanical properties of the concrete. The water absorption rate of Comparative Example 2 (all-natural aggregate) reached 3.01%, which is due to the lack of micro-powder filler, resulting in higher porosity and water absorption, affecting the stability of the concrete. The water absorption rate of Comparative Example 5 (untreated steel slag) reached 3.11%, a high rate, which is due to the formation of interconnected pores by CaO hydration expansion, increasing water absorption and affecting the workability of the concrete.
[0070] Comparative Examples 2 and 3, despite reducing the amount of solid waste, also exhibited low mechanical strength and workability. This indicates that there is a significant synergistic effect among the raw materials of this invention. Through the combination of these raw materials, high-performance concrete can be prepared with a high amount of solid waste, which not only improves the utilization rate of solid waste but also significantly enhances the mechanical and workability properties of the concrete.
[0071] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0072] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for preparing high-strength lightweight aggregate concrete from multiple solid wastes, characterized in that, The composition includes the following components in parts by weight: 50-85 parts solid waste-based sulfoaluminate cement, 10-30 parts crushed stone, 40-70 parts blast furnace slag, 30-55 parts waste ceramic powder, 8-15 parts sand, 25-30 parts waste concrete powder, 35-40 parts steel slag, 1-3 parts silica fume, 1-2 parts additives, and 80-90 parts water.
2. The method for preparing high-strength lightweight aggregate concrete from multi-element solid waste according to claim 1, characterized in that, The solid waste-based sulfoaluminate cement is prepared by means of the following raw materials: 40-60 parts of bauxite tailings, 20-30 parts of fly ash, 10-15 parts of desulfurized gypsum, 5-10 parts of carbide slag, and 0.5-2 parts of flux.
3. The method for preparing high-strength lightweight aggregate concrete from multi-element solid waste according to claim 2, characterized in that, The preparation steps of the solid waste-based sulfoaluminate cement include: Bauxite tailings, fly ash, desulfurized gypsum, and carbide slag are mixed in proportion, and flux is added. The mixture is then calcined at 1250–1350℃ for 30–60 minutes, rapidly cooled to below 200℃, and then desulfurized gypsum is added and mixed to obtain solid waste-based sulfoaluminate cement.
4. The method for preparing high-strength lightweight aggregate concrete from multi-element solid waste according to claim 1, characterized in that, The blast furnace slag has a particle size of 5-20 mm; the waste ceramic powder has a particle size of 10-15 mm; the waste concrete powder has a particle size of 1-1.5 mm; the steel slag has a particle size of 1-2.5 mm; the steel slag is further subjected to saturated steam treatment at 0.8-1.2 MPa for 6-8 hours before use.
5. The method for preparing high-strength lightweight aggregate concrete from multi-element solid waste according to claim 1, characterized in that, The gradation composition and mass percentage of the crushed stone are as follows: 10-20% crushed stone with a particle size <4.75mm, 40-50% crushed stone with a particle size of 4.75-12mm, and 30-40% crushed stone with a particle size of 12-19mm.
6. The method for preparing high-strength lightweight aggregate concrete from multi-element solid waste according to claim 1, characterized in that, The fineness modulus of the sand is 1.6 to 2.2; the additives and their dosages are: 0.5 to 1 part of defoamer, 0.2 to 0.5 parts of dispersant, and 0.3 to 0.5 parts of water-reducing agent.
7. The method for preparing high-strength lightweight aggregate concrete from multi-element solid waste according to claim 1, characterized in that, The dispersant is triethylhexylphosphoric acid and / or polyacrylamide; the defoamer includes organosilicon defoamers; and the water-reducing agent includes lignin sulfonate water-reducing agents.
8. The method for preparing high-strength lightweight aggregate concrete from multi-element solid waste according to any one of claims 1 to 7, characterized in that, Includes the following steps: Solid waste-based sulfoaluminate cement, crushed stone, blast furnace slag, waste ceramic powder, sand, waste concrete powder, steel slag, silica fume, additives and water are mixed, then poured and vibrated in sequence, and finally cured to obtain high-strength lightweight aggregate concrete prepared from multi-element solid waste.
9. The method for preparing high-strength lightweight aggregate concrete from multi-element solid waste according to claim 8, characterized in that, The vibration is performed 5 to 8 times.
10. The method for preparing high-strength lightweight aggregate concrete from multi-element solid waste according to claim 8, characterized in that, The curing temperature is 10–30℃, the curing time is 28–30 days, and the relative humidity is 90–95%.