High-strength lightweight aggregate concrete and preparation method thereof
By using composite lightweight aggregates with multi-layered structural design, the problems of strength and water absorption rate of lightweight aggregate concrete are solved, resulting in lightweight aggregate concrete with high strength and excellent workability, which is suitable for high-rise buildings and large-span structures.
Patent Information
- Application Number
- CN202511897217.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-16
- Publication Date
- 2026-02-17
AI Technical Summary
The existing production process for high-strength lightweight aggregate concrete is complex and difficult to industrialize. Furthermore, the high porosity of lightweight aggregates leads to high water absorption, which affects the homogeneity and workability of the concrete, making it difficult to meet the comprehensive requirements of high strength and excellent workability.
The composite lightweight aggregate with a multi-layer structure is prepared by mixing raw materials such as coal gangue, porous ceramsite, wood granules activated carbon and fumed silica to prepare the core material, combined with metakaolin, microcrystalline glass powder and phosphogypsum to prepare the middle layer, and finally with ferrosilicon manganese slag and magnesium slag to form the outer shell layer, forming a core-shell composite lightweight aggregate, which improves strength and reduces water absorption.
It significantly improves the strength grade of lightweight aggregate concrete to LC50~60, reduces water absorption, solves pump blockage, ensures the homogeneity and workability of concrete, and meets the application requirements of high-end structural engineering.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of lightweight aggregate and concrete processing technology, specifically relating to a high-strength lightweight aggregate concrete and its preparation method. Background Technology
[0002] Lightweight aggregate concrete, due to its excellent properties such as light weight, high strength, thermal insulation, and seismic resistance, has shown great application potential in super high-rise buildings, large-span structures, areas with high seismic fortification requirements, soft soil foundation treatment, and renovation of old buildings. It not only achieves integrated load-bearing and thermal insulation of structures but also represents an important direction for the development of modern industrialized construction. Currently, lightweight aggregates are mainly divided into natural aggregates (such as pumice, volcanic slag, and vermiculite) and artificial aggregates (such as coal gangue, expanded shale, perlite, and fly ash ceramsite). Ideally, lightweight aggregate concrete requires a dry density of 600-1800 kg / m³. 3 Within this range, the mechanical performance requirements also differ for different application areas.
[0003] High-strength lightweight aggregate concrete is typically used in high-rise buildings and large structural components, requiring high mechanical strength grades. However, the performance of the lightweight aggregate itself is currently the key bottleneck limiting its further development: the strength of high-strength lightweight aggregate concrete largely depends on the strength of the aggregate, and most existing artificial lightweight aggregates have limited inherent strength due to their porous structure, making it difficult to further increase the concrete strength after reaching a certain level (approximately LC20-LC30). Producing high-strength lightweight aggregates that can meet the requirements of LC50-LC60 and above is complex and difficult to industrialize, thus restricting its application.
[0004] In addition, lightweight aggregate concrete also has significant problems in terms of construction technology: due to the high porosity and water absorption of lightweight aggregate, it not only makes it easy to cause pump blockage during pumping, but also makes it difficult to control the homogeneity and workability of concrete, affecting the overall performance and durability of the components.
[0005] The existing performance of traditional artificial lightweight aggregates can hardly fully meet the comprehensive requirements of modern civil engineering for high strength and excellent workability. Therefore, researching and developing a new type of high-performance artificial lightweight aggregate with high strength, low water absorption, good particle morphology and stability is of great theoretical and engineering significance for breaking through the performance ceiling of lightweight aggregate concrete and promoting its application in high-end structural engineering. Summary of the Invention
[0006] In view of the content mentioned in the background art, the purpose of this invention is to provide a high-strength lightweight aggregate concrete and its preparation method; by improving and optimizing the aggregate structure, the strength performance of the composite aggregate is effectively improved, thereby significantly improving the strength grade of the prepared lightweight aggregate concrete.
[0007] To achieve the above objectives, the present invention specifically adopts the following technical solution: This invention provides a high-strength lightweight aggregate concrete, the raw materials of which, by weight, include: 850-1020 parts of composite lightweight aggregate, 580-750 parts of river sand, 340-400 parts of cement, 180-210 parts of water, 60-80 parts of silica fume, 55-75 parts of fly ash, 5-7.5 parts of admixtures, and 1.5-3 parts of basalt fiber; The preparation method of the composite lightweight aggregate includes the following steps: Step 1: Mix coal gangue, porous ceramsite, wood-based activated carbon, and fumed silica in a certain proportion, add an appropriate amount of water to granulate, roll to obtain raw material balls, and then sinter them once in a rotary kiln and cool to obtain core material particles for later use. Step 2: Take metakaolin, microcrystalline glass powder, and phosphogypsum, mix them with water to make a viscous slurry, add the viscous slurry to the core material particles and roll them into granules, let them stand and cure, and obtain the intermediate layer particles for later use. Step 3: Take ferrosilicon manganese slag, magnesium slag and sodium silicate solution and stir to obtain slurry. Impregnate the middle layer particles, granulate and shape them, and finally transfer them into a rotary kiln for secondary sintering. After cooling, the composite lightweight aggregate is obtained.
[0008] In a preferred embodiment, the lightweight aggregate concrete comprises the following raw materials by weight: 940 parts of composite lightweight aggregate, 660 parts of river sand, 365 parts of cement, 195 parts of water, 70 parts of silica fume, 65 parts of fly ash, 6.5 parts of admixture, and 2.5 parts of basalt fiber.
[0009] In a preferred embodiment, the fineness modulus of the river sand is 2.0-2.6; the cement is P.II 52.5 silicate cement; and the silica fume has a silica content of not less than 89% and a specific surface area of 18,000-24,000 m². 2 / kg; fly ash is grade II fly ash; admixture is polycarboxylate superplasticizer; basalt fiber length is 10-20 mm, aspect ratio is 50-100.
[0010] In a preferred embodiment, the mass ratio of coal gangue, porous ceramsite, wood-based granular activated carbon, and fumed silica in step one is 10:(2-4):(1.2-1.8):(0.04-0.08).
[0011] As a preferred embodiment, the first sintering in step one involves preheating at 480-600℃ for 45-60 minutes, then heating and sintering at 1080-1150℃ for 1-2 hours, and finally slowly cooling in the furnace to obtain the final product.
[0012] In a preferred embodiment, the mass ratio of core material particles, metakaolin, microcrystalline glass powder, and phosphogypsum in step two is 10:(4-6):(1-2):(2.5-4); the static curing temperature is 70-80℃ and the time is 0.75-1.5 h.
[0013] In a preferred embodiment, the mass ratio of ferrosilicon manganese slag, magnesium slag and intermediate layer particles in step three is (0.6-0.8):(0.2-0.4):1; the mass fraction of the sodium silicate solution is 20%-30%.
[0014] In a preferred embodiment, the secondary sintering temperature in step three is 980-1020℃, and the time is 35-50 min.
[0015] The present invention also provides a method for preparing the above-mentioned high-strength lightweight aggregate concrete, comprising the following steps: S1. Weigh out each ingredient according to the formula and set aside; S2. Dry mix the lightweight aggregate, river sand, cement, silica fume, and fly ash. S3. Add the admixture and water to the dry mix in batches, and stir thoroughly to obtain a uniform mortar mixture; finally, slowly add the basalt fiber and continue stirring until it is evenly dispersed to obtain lightweight aggregate concrete.
[0016] In a preferred embodiment, the compressive strength of the lightweight aggregate concrete is not less than 50 MPa.
[0017] This invention selects coal gangue as the main raw material, making full use of industrial waste and reducing costs. Ceramsite, a porous, low-density material, and additional pores created through the subsequent burning process of wood-based activated carbon effectively reduce density and significantly decrease weight. Fumed silica compensates for structural collapse and strength reduction caused by the porous nature of the material. The core material of this invention provides a good structural foundation for high-strength, low-density composite aggregates. Based on the aforementioned core material, this invention further uses metakaolin, microcrystalline glass powder, and phosphogypsum to prepare an intermediate layer. The highly active Al2O3 and SiO2 in these materials can undergo a cementing reaction, bonding the core particles together to form an intermediate transition layer with a certain strength through bonding reinforcement. Finally, a shell layer is prepared by secondary sintering of ferrosilicon slag and magnesium slag. The ferrosilicon slag and magnesium slag help form a dense and hard outer protective layer, which not only effectively reduces the water absorption rate of the porous core material but also greatly improves the compressive strength of the resulting composite lightweight aggregate, providing a good foundation for the preparation of high-strength lightweight aggregate concrete.
[0018] Compared with the prior art, the beneficial effects of the present invention are: This invention constructs a core-shell composite lightweight aggregate through multi-layer structural design and optimized raw material combination, effectively overcoming the limitations of existing traditional aggregate strength. The resulting lightweight aggregate concrete breaks through the upper limit of mechanical properties, with a strength grade of LC50~60. At the same time, it takes into account low water absorption, reducing pump blockage caused by water absorption, balancing the density difference between aggregate and cement mortar, and ensuring the homogeneity and workability of concrete. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with embodiments. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.
[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0021] Example 1 A method for preparing high-strength lightweight aggregate concrete includes the following steps: 1. Coal gangue, porous ceramsite, wood-based activated carbon, and fumed silica were mixed evenly in a mass ratio of 10:3:1.5:0.06. A small amount of water (12% of dry material) was added, and the mixture was rolled in a disc granulator to obtain raw material pellets. The pellets were then preheated to 540℃ in a rotary kiln for 50 min, then sintered at 1120℃ for 1.5 h, and finally slowly cooled in the furnace to obtain core material pellets. The obtained core material pellets were mixed with metakaolin, microcrystalline glass powder, and phosphogypsum in a mass ratio of 10:5:1.5:3.2. The metakaolin, microcrystalline glass powder, and phosphogypsum were mixed with water (35% of dry material) to form a viscous slurry. The core material pellets were added to the viscous slurry and mixed evenly. The mixture was then rolled and granulated in a disc granulator, and finally cured at 75℃ for 1.2 h to obtain intermediate layer pellets. Take ferromanganese slag, magnesium slag and the obtained intermediate layer particles in a mass ratio of 0.7:0.3:1. Mix the ferromanganese slag, magnesium slag and an equal mass of sodium silicate solution (25%) to obtain a slurry. Then add the intermediate layer particles and impregnate for 30 min. Granulate and shape the slurry. Transfer it to a rotary kiln and heat to 1000℃ for sintering for 45 min. Cool to obtain composite lightweight aggregate.
[0022] 2. Weigh out 940 parts of the above-mentioned composite lightweight aggregate, 660 parts of river sand, 365 parts of cement, 195 parts of water, 70 parts of silica fume, 65 parts of fly ash, 6.5 parts of polycarboxylate superplasticizer, and 2.5 parts of basalt fiber according to the following weight proportions: Dry mix the lightweight aggregate, river sand, cement, silica fume, and fly ash. Add the superplasticizer and water to the dry mix in three batches, stirring thoroughly to obtain a uniform mortar mixture. Finally, slowly add the basalt fiber while continuously stirring until it is evenly dispersed to obtain lightweight aggregate concrete.
[0023] Example 2 A method for preparing high-strength lightweight aggregate concrete includes the following steps: 1. Coal gangue, porous ceramsite, wood-based activated carbon, and fumed silica were mixed evenly in a mass ratio of 10:2:1.2:0.04. A small amount of water (12% of the dry material) was added, and the mixture was rolled in a disc granulator to obtain raw material pellets. The pellets were then preheated to 480℃ in a rotary kiln for 60 min, and then sintered at 1080℃ for 2 h. Finally, the pellets were slowly cooled in the furnace to obtain core material pellets. The obtained core material pellets were mixed with metakaolin, microcrystalline glass powder, and phosphogypsum in a mass ratio of 10:4:1:2.5. The metakaolin, microcrystalline glass powder, and phosphogypsum were mixed with water (35% of the dry material) to form a viscous slurry. The core material pellets were added to the viscous slurry and mixed evenly. The mixture was then rolled and granulated in a disc granulator, and finally cured at 70℃ for 1.5 h to obtain intermediate layer pellets. Take ferromanganese slag, magnesium slag and the obtained intermediate layer particles in a mass ratio of 0.6:0.4:1. Mix the ferromanganese slag, magnesium slag and an equal mass of sodium silicate solution (25%) to obtain a slurry. Add the intermediate layer particles and impregnate for 30 min. Granulate and shape the slurry. Transfer it to a rotary kiln and heat to 980℃ for sintering for 50 min. Cool to obtain composite lightweight aggregate.
[0024] 2. Weigh out 850 parts of the above-mentioned composite lightweight aggregate, 580 parts of river sand, 340 parts of cement, 180 parts of water, 60 parts of silica fume, 55 parts of fly ash, 5 parts of polycarboxylate superplasticizer, and 1.5 parts of basalt fiber according to the following weight proportions: dry mix the lightweight aggregate, river sand, cement, silica fume, and fly ash; add the superplasticizer and water to the dry mix in two batches, and stir thoroughly to obtain a uniform mortar mixture; finally, slowly add the basalt fiber while continuously stirring until it is evenly dispersed to obtain lightweight aggregate concrete.
[0025] Example 3 A method for preparing high-strength lightweight aggregate concrete includes the following steps: 1. Coal gangue, porous ceramsite, wood-based activated carbon, and fumed silica were mixed evenly in a mass ratio of 10:4:1.8:0.08. A small amount of water (12% of the dry material) was added, and the mixture was rolled in a disc granulator to obtain raw material pellets. The pellets were then preheated to 600℃ in a rotary kiln for 45 min, and then sintered at 1150℃ for 1 h. Finally, the pellets were slowly cooled in the furnace to obtain core material pellets. The obtained core material pellets were mixed with metakaolin, microcrystalline glass powder, and phosphogypsum in a mass ratio of 10:6:2:4. The metakaolin, microcrystalline glass powder, and phosphogypsum were mixed with water (35% of the dry material) to make a viscous slurry. The core material pellets were added to the viscous slurry and mixed evenly. The mixture was rolled and granulated in a disc granulator, and finally cured at 80℃ for 0.75 h to obtain intermediate layer pellets. Take ferromanganese slag, magnesium slag and the obtained intermediate layer particles in a mass ratio of 0.8:0.2:1. Mix the ferromanganese slag, magnesium slag and an equal mass of sodium silicate solution (25%) to obtain a slurry. Then add the intermediate layer particles and impregnate for 30 min. Granulate and shape the slurry. Transfer it to a rotary kiln and heat to 1020℃ for sintering for 35 min. Cool to obtain composite lightweight aggregate.
[0026] 2. Weigh out 1020 parts of the above-mentioned composite lightweight aggregate, 750 parts of river sand, 400 parts of cement, 210 parts of water, 80 parts of silica fume, 75 parts of fly ash, 7.5 parts of polycarboxylate superplasticizer, and 3 parts of basalt fiber according to the following weight proportions: dry mix the lightweight aggregate, river sand, cement, silica fume, and fly ash; add the superplasticizer and water to the dry mix in three batches, stirring thoroughly to obtain a uniform mortar mixture; finally, slowly add the basalt fiber while continuously stirring until it is evenly dispersed to obtain lightweight aggregate concrete.
[0027] Comparative Example 1 Referring to the steps and parameters of Embodiment 1 of the present invention, the only difference is that no fumed silica is added to the composite lightweight aggregate core material.
[0028] Comparative Example 2 Referring to the steps and parameters of Embodiment 1 of the present invention, the only difference is that microcrystalline glass powder is not added to the intermediate layer of the composite lightweight aggregate.
[0029] Comparative Example 3 Referring to the steps and parameters of Embodiment 1 of the present invention, the only difference is that ferrosilicon manganese slag, magnesium slag and core material particles are taken at a mass ratio of 0.7:0.3:1. The ferrosilicon manganese slag, magnesium slag and an equal mass of sodium silicate solution (25%) are stirred and mixed to obtain a slurry. Then, the core material particles are added and impregnated for 30 min. The mixture is then granulated and formed, transferred to a rotary kiln and heated to 1000°C for sintering for 45 min. After cooling, the composite lightweight aggregate is obtained.
[0030] Comparative Example 4 Referring to the step parameters of Embodiment 1 of the present invention, the only difference is that the intermediate layer particles in step 1 are used as composite lightweight aggregate.
[0031] Test case The performance of the lightweight aggregate samples used in the above embodiments and comparative examples of the present invention was tested, and the results are shown in Table 1 (testing was conducted in accordance with GB / T 17431.2-2010).
[0032] Table 1. Performance test results of lightweight aggregate samples
[0033] The performance of the lightweight aggregate concrete samples prepared in the above embodiments and comparative examples of the present invention was tested, and the results are shown in Table 2 (testing was conducted in accordance with GB / T 50081-2019).
[0034] Table 2 Performance test results of lightweight aggregate concrete samples
[0035] In summary, the composite lightweight aggregate prepared by this invention exhibits significantly reduced water absorption while maintaining high compressive strength and suitable apparent density. Adjusting the core-shell structure and raw material composition of the composite lightweight aggregate reduces aggregate performance to varying degrees. Furthermore, when the composite lightweight aggregate is used to produce concrete, the concrete prepared with this invention achieves a strength grade of LC50 or higher, a significant improvement compared to traditional lightweight aggregate concrete. This high-strength lightweight aggregate concrete meets the application requirements of super high-rise buildings and large-span structures.
[0036] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they are not intended to limit the present invention. It should be noted that various changes and modifications can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the concept and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A high-strength lightweight aggregate concrete, characterized by, The raw materials include, by weight fraction, 850-1020 parts of composite lightweight aggregate, 580-750 parts of river sand, 340-400 parts of cement, 180-210 parts of water, 60-80 parts of silica fume, 55-75 parts of fly ash, 5-7.5 parts of additive, and 1.5-3 parts of basalt fiber; The preparation method of the composite lightweight aggregate comprises the following steps: Step one: uniformly mix coal gangue, porous ceramsite, wooden granular activated carbon, and fumed silica in a certain proportion, add an appropriate amount of moisture for granulation, roll to obtain green balls, then sinter in a rotary kiln for one time, and cool to obtain core material particles for standby; Step two: mix metakaolin, microcrystalline glass powder, and phosphorus gypsum with water to prepare viscous slurry, add the viscous slurry to the core material particles for rolling granulation, and stand for curing to obtain intermediate layer particles for standby; Step three: mix silicon-manganese slag and magnesium slag with sodium silicate solution to obtain slurry, immerse the intermediate layer particles, granulate and form, and finally sinter in a rotary kiln for two times, and cool to obtain the composite lightweight aggregate.
2. The high-strength lightweight aggregate concrete according to claim 1, characterized in that, The raw materials of the lightweight aggregate concrete include, by weight fraction, 940 parts of composite lightweight aggregate, 660 parts of river sand, 365 parts of cement, 195 parts of water, 70 parts of silica fume, 65 parts of fly ash, 6.5 parts of additive, and 2.5 parts of basalt fiber.
3. The high-strength lightweight aggregate concrete according to claim 1, characterized in that, The river sand has a fineness modulus of 2.0-2.6; the cement is P.II 52.5 Portland cement; the silica fume has a silicon dioxide content of not less than 89% and a specific surface area of 18000-24000 m 2 / kg; the fly ash is II-grade fly ash; the additive is a polycarboxylic acid type water reducing agent; the basalt fiber has a length of 10-20 mm and a length-diameter ratio of 50-100.
4. The high-strength lightweight aggregate concrete according to claim 1, characterized in that, In step one, the mass ratio of coal gangue, porous ceramsite, wooden granular activated carbon, and fumed silica is 10:(2-4):(1.2-1.8):(0.04-0.08).
5. The high strength lightweight aggregate concrete as claimed in claim 1, wherein, In step one, the one-time sintering is preheating at 480-600℃ for 45-60 min, then heating and sintering at 1080-1150℃ for 1-2 h, and finally slowly cooling with the furnace.
6. The high strength lightweight aggregate concrete as claimed in claim 1, wherein, In step two, the mass ratio of core material particles, metakaolin, microcrystalline glass powder, and phosphorus gypsum is 10:(4-6):(1-2):(2.5-4); the temperature for standing and curing is 70-80℃, and the time is 0.75-1.5 h.
7. The high strength lightweight aggregate concrete as claimed in claim 1, wherein, In step three, the mass ratio of silicon-manganese slag, magnesium slag, and intermediate layer particles is (0.6-0.8):(0.2-0.4):1; the mass fraction of the sodium silicate solution is 20%-30%.
8. The high strength lightweight aggregate concrete as claimed in claim 1, wherein, In step three, the temperature for two-time sintering is 980-1020℃, and the time is 35-50 min.
9. A method of producing high-strength lightweight aggregate concrete according to any one of claims 1 to 8, characterized in that, The method comprises the following steps: S1, weigh each raw material according to the formula for standby; S2, dry mix the lightweight aggregate, river sand, cement, silica fume, and fly ash uniformly; S3, add the additive and water to the dry mixture in batches, stir well to obtain a uniform mortar mixture, and then slowly add the basalt fiber and continuously stir to disperse uniformly to obtain the lightweight aggregate concrete.
10. The method of claim 9, wherein the high-strength lightweight aggregate concrete is prepared by mixing the high-strength lightweight aggregate concrete mixture with water in a ratio of 0.3 to 0.
5. The compressive strength of the lightweight aggregate concrete is not less than 50 MPa.