Preparation method of coal gasification slag concrete
By using coal gasification slag to replace fine aggregate in concrete and combining it with a composite activator, the gradation and interface structure were optimized, solving the durability problem of coal gasification slag concrete, improving compressive strength and chloride ion penetration resistance, while simplifying the process and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA ENERGY GRP NINGXIA COAL IND CO LTD
- Filing Date
- 2026-01-16
- Publication Date
- 2026-05-12
AI Technical Summary
Existing technologies for concrete based on coal gasification slag have poor durability, especially in terms of resistance to chloride ion penetration and sulfate attack, and the processing technology is complex and costly.
By replacing fine aggregates in concrete systems with coal gasification slag and combining it with composite activators (CaO-based early strength agents, phosphogypsum, and lithium salts) for gradation optimization, the composition of hydration products and interface structure are regulated through a dual physical and chemical mechanism, thereby optimizing the internal density of concrete.
It significantly improves the compressive strength and chloride ion penetration resistance of concrete, enhances durability, and reduces processing costs and process complexity.
Smart Images
Figure CN122010486A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of concrete technology, and specifically to a method for preparing coal gasification slag concrete. Background Technology
[0002] my country's "dual-carbon" strategy, a far-reaching and influential initiative, aims to actively address the challenges of global climate change and promote a comprehensive green transformation of economic and social development. Within this grand strategic framework, the resource utilization of bulk solid waste has become an urgent and essential requirement. It not only concerns the efficient recycling of resources but is also a key pathway to reducing environmental pollution and carbon emissions, playing an irreplaceable role in building a resource-saving and environmentally friendly society.
[0003] Utilizing coal gasification slag to produce building materials is a major research direction for the clean utilization and sustainable development of coal. In existing technologies, the main focus is on using the aggregate effect and pozzolanic effect of low-carbon coal gasification slag to make bricks, test blocks, and to mix with cement or concrete. However, there are still some technical challenges when coal gasification slag is actually used to produce building materials. For example, the durability of concrete based on coal gasification slag is not good. Summary of the Invention
[0004] The purpose of this invention is to overcome the problem of poor durability of concrete based on coal gasification slag in the prior art, and to provide a method for preparing coal gasification slag concrete that has both high strength and good durability.
[0005] To achieve the above objectives, the present invention provides a method for preparing coal gasification slag concrete, the method comprising: Mix fine aggregates of gravel, sand, and coal gasification slag, cementitious materials, composite activator, and water, wherein: Based on a total mass of 100 parts of the mixed fine aggregate of gravel, sand and coal gasification slag, cementing material, composite activator and water, the amounts of the mixed fine aggregate of gravel, sand and coal gasification slag, cementing material, composite activator and water are 40-45 parts, 24-40 parts, 15-22 parts, 1-5 parts and 5-10 parts respectively, and the mass of the coal gasification slag is 35-65% of the mass of the mixed fine aggregate of sand and coal gasification slag. The composite activator includes CaO-based early strength agent, phosphogypsum, lithium salt and alkaline solution. The particle size distribution of the coal gasification slag includes: ≤10% residue on a 4.75mm square sieve, ≤25% residue on a 2.36mm square sieve, 10-50% residue on a 1.18mm square sieve, 41-70% residue on a 600μm square sieve, 70-92% residue on a 300μm square sieve, and 90-100% residue on a 150μm square sieve. The particle size distribution of the sand includes: ≤5% residue on a 4.75mm square sieve, ≤25% residue on a 2.36mm square sieve, 10-50% residue on a 1.18mm square sieve, 41-70% residue on a 600μm square sieve, 70-92% residue on a 300μm square sieve, and 80-94% residue on a 150μm square sieve.
[0006] Preferably, based on 100 parts of the total mass of the mixed fine aggregate of gravel, sand and coal gasification slag, cementing material, composite activator and water, the amounts of the mixed fine aggregate of gravel, sand and coal gasification slag, cementing material, composite activator and water are 42-44 parts, 25-30 parts, 18-20 parts, 2-4 parts and 6-9 parts, respectively.
[0007] Preferably, the amount of the lithium salt is 1 part by mass, the amount of the CaO-based early strength agent is 5-16 parts, the amount of the phosphogypsum is 10-30 parts, and the amount of the alkaline solution is 3-10 parts.
[0008] Preferably, the cementing material is silicate cement, with the total mass of the sand and coal gasification slag being 100%.
[0009] Preferably, the alkaline solution includes at least one of sodium hydroxide solution and potassium hydroxide solution.
[0010] Preferably, the lithium salt includes at least one of Li₂CO₃ and LiCl.
[0011] Preferably, the specific process of the method includes: Step S1: Mix CaO-based early strength agent, phosphogypsum, lithium salt and alkaline solution to obtain composite activator solution; Step S2: Mix the composite activator solution with cementitious materials, coal gasification slag, sand, gravel and water.
[0012] Preferably, the mixing conditions in step S1 include: a stirring speed of 150~250 r / min and a stirring time of 20~50 s.
[0013] Preferably, the specific process of step S2 includes: mixing the composite activator solution with cementing material, coal gasification slag and part of water, then adding sand and gravel in sequence and mixing, and finally adding the remaining water and mixing.
[0014] Preferably, in step S2, the mixing conditions include: a stirring speed of 50~55 r / min and a stirring time of 100~150 s.
[0015] Through the above technical solution, this invention first replaces the fine aggregate (sand) in the concrete system with coal gasification slag, with a replacement ratio of approximately 35-65%, and limits the gradation requirements of the coal gasification slag and sand to achieve aggregate gradation optimization. Simultaneously, a composite activator is used, employing a dual physical and chemical mechanism to precisely control the composition of hydration products and optimize the interfacial structure during concrete mixing. This innovative technique significantly improves the density of the concrete matrix, making its internal structure more compact and ordered, thereby effectively enhancing the mechanical properties and durability of the concrete, particularly the compressive strength and resistance to chloride ion penetration. The improvement mechanism of this invention is analyzed in detail below: Aggregate density is improved by gradation optimization, and Ca in coal gasification slag is activated by composite activators. 2+ and SiO3 2- The active components create favorable conditions for subsequent chemical reactions. Specifically, the CaO-based early-strength agent introduced into the composite activator can accelerate the hydration reaction, shorten the setting time, and improve early strength; the lithium salt contains Li... + Ca can be replaced in CSH gel 2+ This process helps stabilize the gel structure, reducing expansion and damage caused by alkali-aggregate reaction, and also refines capillary pore size, reducing porosity. The reaction of phosphogypsum with hydrated calcium aluminate forms an ettringite phase; this unique crystal structure can form a dense protective layer within the material, hindering the intrusion of sulfate ions. Based on these mechanisms, the coal gasification slag concrete provided by this invention not only possesses excellent material strength but also improves the durability of concrete materials and effectively enhances resistance to sulfate attack. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the modification mechanism of coal gasification slag concrete provided by the present invention. Detailed Implementation
[0017] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.
[0018] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0019] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or implying the number of technical features indicated. Therefore, unless otherwise stated, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; "multiple" means two or more. The term "comprising" and any variations thereof mean non-exclusive inclusion, where one or more other features, integers, steps, operations, units, components, and / or combinations thereof may be present or added.
[0020] In the practical application of solid waste in the preparation of building materials, when the inventors attempted to use coal gasification slag as a potential alternative material to replace traditional river sand in concrete production, they encountered some urgent technical problems, mainly: 1. Although the activation technology can improve early strength, it is not very effective in improving resistance to chloride ion penetration and precisely controlling resistance to sulfate attack; 2. Although aggregate gradation optimization and interface modification can improve the density of the material, the complexity of the process significantly increases the difficulty of construction; 3. Although the slag-furnace slag-silica fume ternary composite system has the advantage of synergistic strengthening performance, its application is limited by the high material cost and the resulting imbalance in durability indicators.
[0021] Further research by the inventors revealed the following drawbacks in the existing technology: (1) The problem of balancing activity activation and durability and the lack of regulation of the interfacial transition zone (ITZ). In practical research and application, the inventors discovered a prominent contradiction: the balance between activation and durability is difficult to achieve, and the effective control of the interface transition zone is also significantly insufficient. Taking Chinese patent application CN1005645991 as an example, this patent points out that while excessive grinding or chemical activation can indeed significantly improve the early strength of materials in the short term, this approach brings a series of potential risks and problems. From a microstructural perspective, excessive treatment alters the stress distribution within the material, thereby exacerbating the risk of shrinkage cracking. More importantly, for special materials like coal gasification slag, the surface has a dense glassy phase, a characteristic that leads to weakening of the interface transition zone. Therefore, in pursuing high strength, the durability of concrete is severely affected, failing to meet the requirements for long-term stable use in practical engineering processes.
[0022] (2) Lack of synergistic improvement of multiple durability indicators Current technologies in the industry largely focus on single performance indicators, such as compressive strength, while neglecting the synergistic optimization of multiple durability indicators. For example, Chinese patent application CN115521116, while successfully implementing the application of gasification slag to replace fine aggregate, which expands resource utilization to some extent, failed to comprehensively verify a series of important related durability indicators in practical applications, such as resistance to chloride ion penetration and sulfate attack. In real engineering environments, concrete structures often face multiple corrosive factors simultaneously, making a single performance focus insufficient. This lack of synergistic improvement across multiple durability indicators may lead to ineffective guarantee of concrete structure durability during actual use, thereby shortening its service life and increasing maintenance costs.
[0023] (3) The current situation of complex processing technology Some existing solutions involve overly complex processing techniques, such as high-pressure roller milling, drying and grading, and iron removal. The resulting material is used to replace traditional fly ash or mineral powder to improve the overall durability of concrete. While this process can improve material performance to some extent, from a practical standpoint, its complex flow not only increases production time and labor costs but also places higher demands on the stability and reliability of production equipment. In large-scale industrial production, such complex processes may become a significant factor limiting their widespread application.
[0024] (4) The problem of high processing costs Besides the complex processing technology, another significant issue is the high processing cost, especially in powder processing, where the large amount of energy required to power the equipment leads to persistently high energy consumption. Furthermore, as the admixture dosage increases, additional admixtures are often needed to ensure good workability of the concrete. While these admixtures can improve concrete performance to some extent, they further increase production costs. In an increasingly competitive market, high processing costs undoubtedly reduce the product's market competitiveness and limit its wider application.
[0025] Based on the above technical problems, this invention addresses the potential for improvement. Firstly, it partially replaces the fine aggregate in the concrete system. Based on in-depth research into material properties and structural characteristics, it introduces new materials with specific functions to improve overall performance. Secondly, it maintains the original concrete preparation process unchanged. This decision fully considers the maturity and stability of existing processes, avoiding uncertainties and technical risks caused by process changes, thereby achieving production with lower cost and fewer process steps. Finally, while ensuring that the concrete strength meets relevant standards, it creatively proposes a three-level linkage technology scheme of "aggregate gradation-composite activation-durability synergy." This technology, based on in-depth theoretical research and extensive experimental verification, uses a combination of physical and chemical methods to give the prepared concrete high resistance to chloride ion penetration. This achievement not only effectively solves the utilization problem of coal gasification slag but also further optimizes the durability of solid waste concrete. Specifically, this invention provides a method for preparing coal gasification slag concrete, the method comprising: Mix fine aggregates of gravel, sand, and coal gasification slag, cementitious materials, composite activator, and water, wherein: Based on a total mass of 100 parts of the mixed fine aggregate of gravel, sand, and coal gasification slag, cementitious material, composite activator, and water, the amounts of the mixed fine aggregate of gravel, sand, and coal gasification slag, cementitious material, composite activator, and water are 40-45 parts, 24-40 parts, 15-22 parts, 1-5 parts, and 5-10 parts, respectively, and the mass of the coal gasification slag is 35-65% of the mass of the mixed fine aggregate of sand and coal gasification slag. The composite activator includes a CaO-based early strength agent, phosphogypsum, lithium salt, and alkaline solution. The particle size distribution of the coal gasification slag includes: ≤10% residue on a 4.75mm square sieve, ≤25% residue on a 2.36mm square sieve, 10-50% residue on a 1.18mm square sieve, 41-70% residue on a 600μm square sieve, 70-92% residue on a 300μm square sieve, and 90-100% residue on a 150μm square sieve. The particle size distribution of the sand includes: ≤5% residue on a 4.75mm square sieve, ≤25% residue on a 2.36mm square sieve, 10-50% residue on a 1.18mm square sieve, 41-70% residue on a 600μm square sieve, 70-92% residue on a 300μm square sieve, and 80-94% residue on a 150μm square sieve.
[0026] It should be noted that, under normal circumstances, the particle size distribution of raw materials such as coal gasification slag and sand obtained from procurement or recycling is uneven. In this invention, a mixed fine aggregate of coal gasification slag and sand that meets the gradation requirements of this invention is obtained through multi-stage screening.
[0027] This invention first replaces the fine aggregate (sand) in the concrete system with coal gasification slag, with a replacement ratio of approximately 35-65%, and limits the gradation requirements of the coal gasification slag and sand to achieve aggregate gradation optimization. At the same time, a composite activator is used to achieve precise control of the composition of hydration products and optimized reconstruction of the interface structure during the concrete mixing process through a dual physical and chemical mechanism. This innovative technical means greatly improves the density of the concrete matrix, making its internal structure more compact and orderly, thereby effectively improving the mechanical properties and durability of the concrete, especially the compressive strength and resistance to chloride ion penetration.
[0028] Combination Figure 1 As shown, the improvement mechanism of the present invention is specifically analyzed as follows: Aggregate density is improved by gradation optimization, and Ca in coal gasification slag is activated by composite activators. 2+ and SiO3 2- The active components create favorable conditions for subsequent chemical reactions. Specifically, the CaO-based early-strength agent introduced into the composite activator can accelerate the hydration reaction, shorten the setting time, and improve early strength; the lithium salt contains Li... + Ca can be replaced in CSH gel 2+ This process helps stabilize the gel structure, reducing expansion and damage caused by alkali-aggregate reaction, and also refines capillary pore size, reducing porosity. The reaction of phosphogypsum with hydrated calcium aluminate forms an ettringite phase; this unique crystal structure can form a dense protective layer within the material, hindering the intrusion of sulfate ions. Based on these mechanisms, the coal gasification slag concrete provided by this invention not only possesses excellent material strength but also improves the durability of concrete materials and effectively enhances resistance to sulfate attack.
[0029] In a preferred embodiment, based on 100 parts by total mass of the mixed fine aggregate, cementitious material, composite activator, and water of the gravel, sand, and coal gasification slag, the amounts of the mixed fine aggregate, cementitious material, composite activator, and water are 42-44 parts, 25-30 parts, 18-20 parts, 2-4 parts, and 6-9 parts, respectively. More preferably, based on 100 parts by total mass of the mixed fine aggregate, cementitious material, composite activator, and water of the gravel, sand, and coal gasification slag, the amounts of the mixed fine aggregate, cementitious material, composite activator, and water are 43 parts, 27 parts, 19 parts, 3 parts, and 8 parts, respectively.
[0030] In some embodiments of the present invention, with the lithium salt being 1 part by mass, the amount of the CaO-based early strength agent is 5 to 16 parts, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16 parts; the amount of the phosphogypsum is 10 to 30 parts, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24 parts. The amount of alkaline solution used is 3 to 10 parts, and the concentration of the alkali in the alkaline solution is 8 to 12 mol / L. Specifically, the amount of alkaline solution used can be, for example, 3, 4, 5, 6, 7, 8, 9, or 10 parts; in addition, the concentration of the alkali in the alkaline solution can be, for example, 8 mol / L, 9 mol / L, 10 mol / L, 11 mol / L, or 12 mol / L, preferably 10 mol / L. In a preferred case, the mass of the lithium salt is 1 part, the amount of the CaO-based early strength agent is 10 parts, the amount of the phosphogypsum is 20 parts, and the amount of the alkali is 5 parts.
[0031] In some embodiments of the present invention, the cementing material is silicate cement, preferably ordinary silicate cement, including but not limited to any one of ordinary silicate cement with strength grades of 42.5 and 52.5R, more preferably ordinary silicate cement with a strength grade of 42.5.
[0032] In some embodiments of the present invention, the CaO-based early-strength agent may be selected from conventional CaO-based early-strength agents used in the concrete field, including but not limited to at least one of calcium chloride and calcium sulfate. Preferably, the CaO-based early-strength agent is calcium sulfate.
[0033] In some embodiments of the present invention, the alkaline solution may be an aqueous solution of a conventional alkaline substance, specifically at least one selected from sodium hydroxide solution and potassium hydroxide solution. Preferably, the alkaline solution is a sodium hydroxide solution.
[0034] In some embodiments of the present invention, the lithium salt may be a conventional lithium salt, specifically at least one selected from Li₂CO₃ and LiCl. Preferably, the lithium salt is Li₂CO₃.
[0035] In this invention, the process of preparing coal gasification slag concrete by mixing sand, coal gasification slag, composite activator, and water can follow the existing concrete preparation process, mainly including material mixing to prepare the concrete mixture, pouring into the mold, molding and demolding, CO2 curing, and conventional curing. Preferably, to improve the activation effect of the composite activator in the coal gasification slag concrete, the composite activator, cementitious material, and coal gasification slag can be mixed with a portion of water first, and then mixed with the remaining materials.
[0036] Specifically, in some embodiments of the present invention, the specific process of the method includes: Step S1: Mix CaO-based early strength agent, phosphogypsum, lithium salt and alkaline solution to obtain composite activator solution; Step S2: Mix the composite activator solution with cementitious materials, coal gasification slag, sand, gravel and water.
[0037] A composite activator solution is prepared by first mixing CaO-based early strength agent, phosphogypsum, lithium salt, and alkaline solution. Then, the composite activator solution is thoroughly mixed with the remaining materials such as cementitious materials, coal gasification slag, sand, gravel, and water. In this way, each component of the composite activator is completely dissolved and mixed evenly in the solution, resulting in a composite activator solution containing multiple active ingredients. These active components fully exert their effects during the subsequent stirring process with the cementitious materials to form a stable gel structure, effectively improving the mechanical properties and durability of the materials.
[0038] In some embodiments of the present invention, the mixing conditions in step S1 include: a stirring speed of 150-250 r / min, for example, 150 r / min, 160 r / min, 170 r / min, 180 r / min, 190 r / min, 200 r / min, 210 r / min, 220 r / min, 230 r / min, 240 r / min, or 250 r / min; and a stirring time of 20-50 s, for example, 20 s, 25 s, 30 s, 35 s, 40 s, 45 s, or 50 s. Further, the mixing in step S1 can be carried out in a high-speed dispersing mixer. Through thorough stirring under the above conditions, complete dissolution and uniform mixing of all materials are ensured, resulting in a clear and transparent composite activator solution.
[0039] In some embodiments of the present invention, the specific process of step S2 includes: mixing the composite activator solution with cementing material, coal gasification slag and part of water, then adding sand and gravel in sequence and mixing, and finally adding the remaining water and mixing.
[0040] In some embodiments of the present invention, the mixing conditions in step S2 include: a stirring speed of 50-55 r / min, for example, 50 r / min, 51 r / min, 52 r / min, 53 r / min, 54 r / min, or 55 r / min; and a stirring time of 100-150 s, for example, 100 s, 110 s, 120 s, 130 s, 140 s, or 150 s. Further, the mixing in step S2 can be carried out in a concrete mixer, and by maintaining appropriate stirring speed and stirring time, the uniformity of the concrete quality can be ensured.
[0041] The following examples further illustrate the preparation method of coal gasification slag concrete according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.
[0042] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.
[0043] Information on some of the raw materials used in the following embodiments and comparative examples is listed below: The coal gasification slag was purchased from Ningxia Coal Basic Construction Co., Ltd., and is rich in SiO2, Al2O3 and residual carbon. The cementitious material was P·O 42.5 grade cement purchased from China United Cement Group Co., Ltd., whose main component was calcium silicate. The gravel is 5~20mm continuous-sized crushed stone that meets the requirements of GB / T 14685 standard; The CaO-based early strength agent is CaSO4, a white powder with a density of 2.96 g / cm³. 3 ; Phosphogypsum, the core component of which is calcium sulfate dihydrate (CaSO4). 2H2O), with a mass fraction of 75-95%.
[0044] Example 1 (1) The coal gasification slag is subjected to multi-stage screening to obtain coal gasification slag particles that meet the following particle size distribution requirements: 5% of the residue passing through a 4.75mm square sieve, 20% of the residue passing through a 2.36mm square sieve, 40% of the residue passing through a 1.18mm square sieve, 65% of the residue passing through a 600μm square sieve, 70% of the residue passing through a 300μm square sieve, and 90% of the residue passing through a 150μm square sieve.
[0045] (2) The manufactured sand is subjected to multi-stage sieving to obtain manufactured sand that meets the following particle size distribution requirements: 5% of the residue passing through a 4.75mm square sieve, 20% of the residue passing through a 2.36mm square sieve, 40% of the residue passing through a 1.18mm square sieve, 70% of the residue passing through a 600μm square sieve, 80% of the residue passing through a 300μm square sieve, and 90% of the residue passing through a 150μm square sieve.
[0046] (3) Weigh 1 part by mass of Li2CO3, 10 parts by mass of CaO-based early strength agent, 21 parts by mass of phosphogypsum and 5 parts by mass of 10mol / L NaOH solution. Add Li2CO3, CaO-based early strength agent and phosphogypsum to NaOH solution and stir at 200r / min for 30s in a high-speed dispersing mixer to obtain a clear and transparent composite activator solution.
[0047] (4) Weigh 3 parts by mass of the composite activator solution prepared in step (3), 17 parts by mass of the sand after screening in step (2), 10 parts by mass of the coal gasification slag after screening in step (1), 8 parts by mass of water, 43 parts by mass of gravel and 19 parts by mass of cementitious material. First, add the composite activator solution, cementitious material, coal gasification slag and 3 parts by mass of water to the concrete mixer and mix evenly. Then, add sand and gravel to the mixer in sequence and mix. Finally, add the remaining 5 parts by mass of water to the mixer and stir at a speed of 52 r / min for 120 s to obtain the concrete mixture.
[0048] (5) The concrete mixture prepared in step (4) is poured into the mold and vibrated. Then, it is left to stand for 24 hours at a temperature of 21℃ and a relative humidity of 95% before being demolded. The demolded specimen is placed in a standard curing room and cured for 28 days to obtain coal gasification slag concrete specimen blocks.
[0049] Example 2 (1) The coal gasification slag is subjected to multi-stage screening to obtain coal gasification slag particles that meet the following particle size distribution requirements: 5% of the residue passing through a 4.75mm square sieve, 20% of the residue passing through a 2.36mm square sieve, 40% of the residue passing through a 1.18mm square sieve, 65% of the residue passing through a 600μm square sieve, 70% of the residue passing through a 300μm square sieve, and 90% of the residue passing through a 150μm square sieve.
[0050] (2) The manufactured sand is subjected to multi-stage sieving to obtain manufactured sand that meets the following particle size distribution requirements: 5% of the residue passing through a 4.75mm square sieve, 20% of the residue passing through a 2.36mm square sieve, 40% of the residue passing through a 1.18mm square sieve, 70% of the residue passing through a 600μm square sieve, 80% of the residue passing through a 300μm square sieve, and 90% of the residue passing through a 150μm square sieve.
[0051] (3) Weigh 1 part by mass of Li2CO3, 5 parts by mass of CaO-based early strength agent, 20 parts by mass of phosphogypsum and 5 parts by mass of 10mol / L NaOH solution. Add Li2CO3, CaO-based early strength agent and phosphogypsum to NaOH solution and stir at 200r / min for 30s in a high-speed dispersing mixer to obtain a clear and transparent composite activator solution.
[0052] (4) Weigh 3 parts by mass of the composite activator solution prepared in step (3), 15 parts by mass of the sand after screening in step (2), 12 parts by mass of the coal gasification slag after screening in step (1), 8 parts by mass of water, 43 parts by mass of gravel and 19 parts by mass of cementitious material. First, add the composite activator solution, cementitious material, coal gasification slag and 3 parts by mass of water to the concrete mixer and mix evenly. Then, add sand and gravel to the mixer in sequence and mix. Finally, add the remaining 5 parts by mass of water to the mixer and stir at a speed of 52 r / min for 120 s to obtain the concrete mixture.
[0053] (5) The concrete mixture prepared in step (4) is poured into the mold and vibrated. Then, it is left to stand for 24 hours at a temperature of 21℃ and a relative humidity of 95% before being demolded. The demolded specimen is placed in a standard curing room and cured for 28 days to obtain coal gasification slag concrete specimen blocks.
[0054] Example 3 (1) The coal gasification slag is subjected to multi-stage screening to obtain coal gasification slag particles that meet the following particle size distribution requirements: 5% of the residue passing through a 4.75mm square sieve, 20% of the residue passing through a 2.36mm square sieve, 40% of the residue passing through a 1.18mm square sieve, 65% of the residue passing through a 600μm square sieve, 70% of the residue passing through a 300μm square sieve, and 90% of the residue passing through a 150μm square sieve.
[0055] (2) The manufactured sand is subjected to multi-stage sieving to obtain manufactured sand that meets the following particle size distribution requirements: 5% of the residue passing through a 4.75mm square sieve, 20% of the residue passing through a 2.36mm square sieve, 40% of the residue passing through a 1.18mm square sieve, 70% of the residue passing through a 600μm square sieve, 80% of the residue passing through a 300μm square sieve, and 90% of the residue passing through a 150μm square sieve.
[0056] (3) Weigh 1 part by mass of Li2CO3, 10 parts by mass of CaO-based early strength agent, 20 parts by mass of phosphogypsum and 5 parts by mass of 10mol / L NaOH solution. Add Li2CO3, CaO-based early strength agent and phosphogypsum to NaOH solution and stir at 200r / min for 30s in a high-speed dispersing mixer to obtain a clear and transparent composite activator solution.
[0057] (4) Weigh 3 parts by mass of the composite activator solution prepared in step (3), 14 parts by mass of the sand after screening in step (2), 13 parts by mass of the coal gasification slag after screening in step (1), 8 parts by mass of water, 43 parts by mass of gravel and 19 parts by mass of cementitious material. First, add the composite activator solution, cementitious material, coal gasification slag and 3 parts by mass of water to the concrete mixer and mix evenly. Then, add sand and gravel to the mixer in sequence and mix. Finally, add the remaining 5 parts by mass of water to the mixer and stir at a speed of 52 r / min for 120 s to obtain the concrete mixture.
[0058] (5) The concrete mixture prepared in step (4) is poured into the mold and vibrated. Then, it is left to stand for 24 hours at a temperature of 21℃ and a relative humidity of 95% before being demolded. The demolded specimen is placed in a standard curing room and cured for 28 days to obtain coal gasification slag concrete specimen blocks.
[0059] Example 4 (1) The coal gasification slag is subjected to multi-stage screening to obtain coal gasification slag particles that meet the following particle size distribution requirements: 5% of the residue passing through a 4.75mm square sieve, 20% of the residue passing through a 2.36mm square sieve, 40% of the residue passing through a 1.18mm square sieve, 65% of the residue passing through a 600μm square sieve, 70% of the residue passing through a 300μm square sieve, and 90% of the residue passing through a 150μm square sieve.
[0060] (2) The manufactured sand is subjected to multi-stage sieving to obtain manufactured sand that meets the following particle size distribution requirements: 5% of the residue passing through a 4.75mm square sieve, 20% of the residue passing through a 2.36mm square sieve, 40% of the residue passing through a 1.18mm square sieve, 70% of the residue passing through a 600μm square sieve, 80% of the residue passing through a 300μm square sieve, and 90% of the residue passing through a 150μm square sieve.
[0061] (3) Weigh 1 part by mass of Li2CO3, 10 parts by mass of CaO-based early strength agent, 10 parts by mass of phosphogypsum and 5 parts by mass of 10mol / L NaOH solution. Add Li2CO3, CaO-based early strength agent and phosphogypsum to NaOH solution and stir at 200r / min for 30s in a high-speed dispersing mixer to obtain a clear and transparent composite activator solution.
[0062] (4) Weigh 3 parts by mass of the composite activator solution prepared in step (3), 12 parts by mass of the sand after screening in step (2), 15 parts by mass of the coal gasification slag after screening in step (1), 8 parts by mass of water, 43 parts by mass of gravel and 19 parts by mass of cementitious material. First, add the composite activator solution, cementitious material, coal gasification slag and 3 parts by mass of water to the concrete mixer and mix evenly. Then, add sand and gravel to the mixer in sequence and mix. Finally, add the remaining 5 parts by mass of water to the mixer and stir at a speed of 52 r / min for 120 s to obtain the concrete mixture.
[0063] (5) The concrete mixture prepared in step (4) is poured into the mold and vibrated. Then, it is left to stand for 24 hours at a temperature of 21℃ and a relative humidity of 95% before being demolded. The demolded specimen is placed in a standard curing room and cured for 28 days to obtain coal gasification slag concrete specimen blocks.
[0064] Example 5 (1) The coal gasification slag is subjected to multi-stage screening to obtain coal gasification slag particles that meet the following particle size distribution requirements: 5% of the residue passing through a 4.75mm square sieve, 20% of the residue passing through a 2.36mm square sieve, 40% of the residue passing through a 1.18mm square sieve, 65% of the residue passing through a 600μm square sieve, 70% of the residue passing through a 300μm square sieve, and 90% of the residue passing through a 150μm square sieve.
[0065] (2) The manufactured sand is subjected to multi-stage sieving to obtain manufactured sand that meets the following particle size distribution requirements: 5% of the residue passing through a 4.75mm square sieve, 20% of the residue passing through a 2.36mm square sieve, 40% of the residue passing through a 1.18mm square sieve, 70% of the residue passing through a 600μm square sieve, 80% of the residue passing through a 300μm square sieve, and 90% of the residue passing through a 150μm square sieve.
[0066] (3) Weigh 1 part by mass of Li2CO3, 10 parts by mass of CaO-based early strength agent, 25 parts by mass of phosphogypsum and 5 parts by mass of 10mol / L NaOH solution. Add Li2CO3, CaO-based early strength agent and phosphogypsum to NaOH solution and stir at 200r / min for 30s in a high-speed dispersing mixer to obtain a clear and transparent composite activator solution.
[0067] (4) Weigh 3 parts by mass of the composite activator solution prepared in step (3), 10 parts by mass of the sand after screening in step (2), 17 parts by mass of the coal gasification slag after screening in step (1), 8 parts by mass of water, 43 parts by mass of gravel and 19 parts by mass of cementitious material. First, add the composite activator solution, cementitious material, coal gasification slag and 3 parts by mass of water to the concrete mixer and mix evenly. Then, add sand and gravel to the mixer in sequence. Finally, add the remaining 5 parts by mass of water to the mixer and stir at a speed of 52 r / min for 120 s to obtain the concrete mixture.
[0068] (5) The concrete mixture prepared in step (4) is poured into the mold and vibrated. Then, it is left to stand for 24 hours at a temperature of 21℃ and a relative humidity of 95% before being demolded. The demolded specimen is placed in a standard curing room and cured for 28 days to obtain coal gasification slag concrete specimen blocks.
[0069] Comparative Example 1 (1) The coal gasification slag is subjected to multi-stage screening to obtain coal gasification slag particles that meet the following particle size distribution requirements: 5% of the residue passing through a 4.75mm square sieve, 20% of the residue passing through a 2.36mm square sieve, 40% of the residue passing through a 1.18mm square sieve, 65% of the residue passing through a 600μm square sieve, 70% of the residue passing through a 300μm square sieve, and 90% of the residue passing through a 150μm square sieve.
[0070] (2) The manufactured sand is subjected to multi-stage sieving to obtain manufactured sand that meets the following particle size distribution requirements: 5% of the residue passing through a 4.75mm square sieve, 20% of the residue passing through a 2.36mm square sieve, 40% of the residue passing through a 1.18mm square sieve, 70% of the residue passing through a 600μm square sieve, 80% of the residue passing through a 300μm square sieve, and 90% of the residue passing through a 150μm square sieve.
[0071] (3) Weigh 14 parts by weight of sand after screening in step (2), 13 parts by weight of coal gasification slag after screening in step (1), 45 parts by weight of gravel, 20 parts by weight of cementitious material and 8 parts by weight of water, put them into a concrete mixer, and stir at a speed of 52 r / min for 120 s to obtain concrete mixture.
[0072] (4) The concrete mixture prepared in step (3) is poured into the mold and vibrated. Then, it is left to stand for 24 hours at a temperature of 21℃ and a relative humidity of 95% before being demolded. The demolded specimen is placed in a standard curing room for curing for 28 days to obtain concrete test blocks.
[0073] Comparative Example 2 Coal gasification slag-based concrete blocks were prepared according to the method in Example 3, except that multi-stage screening of the coal gasification slag and sand was not performed. The particle size distribution of the coal gasification slag and sand is as follows: (1) The particle size distribution of coal gasification slag is as follows: 5% of the residue passing through a 4.75mm square sieve, 20% of the residue passing through a 2.36mm square sieve, 40% of the residue passing through a 1.18mm square sieve, 65% of the residue passing through a 600μm square sieve, 70% of the residue passing through a 300μm square sieve, and 90% of the residue passing through a 150μm square sieve; (2) The particle size distribution of sand is as follows: 5% of the residue passing through a 4.75mm square sieve, 20% of the residue passing through a 2.36mm square sieve, 40% of the residue passing through a 1.18mm square sieve, 70% of the residue passing through a 600μm square sieve, 80% of the residue passing through a 300μm square sieve, and 90% of the residue passing through a 150μm square sieve.
[0074] Test case The mechanical and durability properties of the concrete specimens prepared in each comparative example were tested. The test methods and results are as follows: (1) Pore characteristics According to standard T / CECS 100423 "Fine Aggregate from Coal Gasification Slag for Concrete and Mortar", the gradation of fine aggregate in concrete made from coal gasification slag and sand was tested. The results showed that the gradation of sand and coal gasification slag used in each embodiment met the requirements of Zone 2 of T / CECS 100423 "Fine Aggregate from Coal Gasification Slag for Concrete and Mortar".
[0075] (2) Compressive strength The compressive strength was tested according to standard GB / T 50081 "Standard for Test Methods of Physical and Mechanical Properties of Concrete".
[0076] (3) Resistance to chloride ion penetration The chloride ion permeability test was conducted according to standard GB / T 50082 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete".
[0077] (4) Resistance to sulfate attack The sulfate resistance test was conducted in accordance with the standard GB / T 50082 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete".
[0078] The performance test results of the concrete test blocks prepared in each embodiment and comparative example are shown in Table 1. The "replacement rate" in Table 1 refers to the percentage of coal gasification slag in the total mass of sand and coal gasification slag.
[0079] Table 1
[0080] As shown in Table 1, compared with the coal gasification slag concrete without the addition of the composite activator, the coal gasification slag concrete prepared with the addition of the composite activator in the embodiments of the present invention exhibits significantly improved antioxidant strength, as well as significantly enhanced resistance to chloride ion penetration and sulfate attack. Specifically, the compressive strength under optimal conditions increases by as much as 28%, reaching its optimal level when the replacement rate of coal gasification slag is 48%. Furthermore, the coal gasification slag concrete exhibits the best resistance to chloride ion penetration at a rate of 696C when the replacement rate is 48%, demonstrating excellent resistance to chloride ion penetration. In addition, the sulfate attack resistance of the coal gasification slag concrete gradually increases with the increase of the coal gasification slag replacement rate. When the replacement rate is 63%, the sulfate attack resistance efficiency of the coal gasification slag concrete reaches 90%, demonstrating outstanding sulfate attack resistance. In summary, the coal gasification slag concrete prepared according to the embodiments of the present invention exhibits significant advantages in both compressive strength and durability.
[0081] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for preparing coal gasification slag concrete, characterized in that, The method includes: Mix gravel, sand, coal gasification slag, cementitious materials, composite activator, and water, wherein: Based on a total mass of 100 parts for the aggregates of gravel, sand, coal gasification slag, cementing material, composite activator, and water, the amounts of the mixture of gravel, sand, and coal gasification slag, cementing material, composite activator, and water are 40-45 parts, 12-40 parts, 8-22 parts, 1-5 parts, and 5-10 parts, respectively. The mass of the coal gasification slag is 35-65% of the mass of the fine aggregate mixture of sand and coal gasification slag. The composite activator includes CaO-based early strength agent, phosphogypsum, lithium salt, and alkaline solution. The particle size distribution of the coal gasification slag includes: ≤10% residue on a 4.75mm square sieve, ≤25% residue on a 2.36mm square sieve, 10-50% residue on a 1.18mm square sieve, 41-70% residue on a 600μm square sieve, 70-92% residue on a 300μm square sieve, and 90-100% residue on a 150μm square sieve. The particle size distribution of the sand includes: ≤5% residue on a 4.75mm square sieve, ≤25% residue on a 2.36mm square sieve, 10-50% residue on a 1.18mm square sieve, 41-70% residue on a 600μm square sieve, 70-92% residue on a 300μm square sieve, and 80-94% residue on a 150μm square sieve.
2. The method according to claim 1, characterized in that, With the lithium salt as 1 part by mass and the total mass of the mixed fine aggregate of gravel, sand and coal gasification slag, cementing material, composite activator and water as 100 parts by mass, the amounts of the mixed fine aggregate of gravel, sand and coal gasification slag, cementing material, composite activator and water are 42-44 parts, 25-30 parts, 18-20 parts, 2-4 parts and 6-9 parts, respectively.
3. The method according to claim 1 or 2, characterized in that, The amount of the lithium salt is 1 part by mass, the amount of the CaO-based early strength agent is 5-16 parts, the amount of the phosphogypsum is 10-30 parts, the amount of the alkaline solution is 3-10 parts, and the concentration of the alkali in the alkaline solution is 8-12 mol / L.
4. The method according to any one of claims 1-3, characterized in that, The cementing material is silicate cement.
5. The method according to any one of claims 1-4, characterized in that, The alkaline solution includes at least one of sodium hydroxide solution and potassium hydroxide solution.
6. The method according to any one of claims 1-5, characterized in that, The lithium salt includes at least one of Li₂CO₃ and LiCl.
7. The method according to any one of claims 1-6, characterized in that, The specific process of the method includes: Step S1: Mix CaO-based early strength agent, phosphogypsum, lithium salt and alkaline solution to obtain composite activator solution; Step S2: Mix the composite activator solution with coal gasification slag, cementing material, sand, gravel and water.
8. The method according to claim 7, characterized in that, The mixing conditions in step S1 include: a stirring speed of 150~250 r / min and a stirring time of 20~50 s.
9. The method according to claim 7 or 8, characterized in that, The specific process of step S2 includes: mixing the composite activator solution with cementitious materials, coal gasification slag and some water, then adding sand and gravel in sequence and mixing, and finally adding the remaining water and mixing.
10. The method according to any one of claims 7-9, characterized in that, In step S2, the mixing conditions include: a stirring speed of 50~55 r / min and a stirring time of 100~150 s.