High-solid-waste green low-carbon concrete and preparation method thereof
By using low-carbon cementitious materials based on metal tailings and recycled aggregates, the pore structure of concrete is optimized, solving the problems of high carbon emissions and low solid waste utilization in concrete production. This enables the preparation of high-performance green and low-carbon concrete, reducing material costs and improving strength performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHONGQING UNIV
- Filing Date
- 2026-03-17
- Publication Date
- 2026-06-09
Smart Images
Figure CN122167121A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of concrete material preparation technology, specifically relating to a high-solid-waste green low-carbon concrete and its preparation method. Background Technology
[0002] The cement and concrete products industry is a crucial foundation and pillar industry for my country's national economic development, playing an irreplaceable role in promoting infrastructure construction, accelerating urbanization, and supporting the modern industrial system. However, this industry is also one of the sectors with the highest concentration of natural resource consumption and energy dependence. Its carbon dioxide emissions account for approximately 13% of the nation's total carbon emissions, making it one of the major sources of carbon emissions in the industrial sector, thus making a green and low-carbon transformation an urgent task.
[0003] At the same time, my country's annual production of bulk solid waste has exceeded 10 billion tons, of which industrial solid waste accounts for about 4 billion tons and construction solid waste about 2 billion tons, a massive scale that continues to grow. These solid wastes currently suffer from problems such as low comprehensive utilization rates, limited disposal channels, and low resource recovery rates, not only occupying land and polluting the environment but also causing serious waste of resources.
[0004] Therefore, how to significantly reduce carbon emissions in the concrete production process while ensuring industry development and supply security, and how to promote the large-scale, high-value-added resource utilization of bulk solid waste, has become a core issue and key breakthrough for promoting the green, low-carbon, and sustainable development of the concrete industry.
[0005] In concrete production, silicate cement has traditionally been used as the key cementitious component. To address its high carbon emissions, cementitious materials with a high solid waste content, primarily composed of industrial solid waste such as metal tailings, can be used as a substitute. This material system not only enables large-scale utilization of industrial solid waste, but research also shows that its life-cycle carbon emissions are approximately 80% lower than conventional cement. On the other hand, for the largest aggregate component in concrete, recycled aggregates can replace natural sand and gravel. Recycled aggregates are derived from the resource recovery of construction waste, including waste concrete and waste bricks and tiles, and are prepared through multiple processes such as crushing, cleaning, and grading. This technological approach can significantly alleviate dependence on and over-exploitation of natural sand and gravel resources, while effectively solving the land occupation and environmental pollution problems caused by the accumulation of construction solid waste. Summary of the Invention
[0006] In view of this, the purpose of this invention is to provide a high-solid-waste green low-carbon concrete and its preparation method. By synergistically utilizing metal tailings-based low-carbon cementitious materials and recycled aggregates from construction waste, high-solid-waste green low-carbon concrete can be prepared. This technology system is expected to significantly reduce the carbon footprint of the entire construction process, promote the transformation of the building materials industry towards a circular economy model, and provide key material support for the sustainable development of the construction industry.
[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention discloses a high-solid-waste green low-carbon concrete, which is composed of 450-550 parts of cementitious materials, 1270-1340 parts of aggregate system, 7.3-16.4 parts of functional additives, and 148-168 parts of auxiliary materials; The cementitious material is composed of steel slag, desulfurized gypsum, mineral powder, and metal tailings in a mass ratio of 8:12:30:45, and a composite activator accounting for 5% of the total weight of steel slag, desulfurized gypsum, mineral powder, and metal tailings. The cementitious material is composed of sodium sulfate and solid alkali slag in a mass ratio of 1:1. The aggregate consists of 600-650 parts of construction solid waste and 670-690 parts of manufactured sand; The functional additives include 1.5-3 parts of micro-nano interface reinforcing agent and 0.5-1% of recycled aggregate pretreatment agent in construction solid waste; the micro-nano interface reinforcing agent is composed of silica fume composite slurry and redispersible latex powder in a mass ratio of 7:3, and the recycled aggregate pretreatment agent is lithium silicate solution. The auxiliary material consists of 140-160 parts water and 6-8 parts water-reducing agent, wherein the water-reducing agent is a polycarboxylate-based water-reducing agent.
[0008] Furthermore, the steel slag has a particle size ≤45μm, the mineral powder is S95 grade mineral powder, the metal tailings have a particle size ≤80μm; the manufactured sand has a fineness modulus of 2.3-2.8 and a stone powder content ≤10%, and the construction solid waste has a 5-20mm continuous gradation.
[0009] Furthermore, the silica fume composite slurry is composed of silica fume: water: dispersant in a ratio of 100:85:1.5, and its solid content is 40%.
[0010] Furthermore, a method for preparing high-solid-waste green low-carbon concrete includes the following steps: S1: Place the construction solid waste in a sealed pretreatment tank and vacuum it to -0.08 MPa for 10 minutes. Then, extract the pore air and maintain the vacuum state. Pump in the preheated recycled aggregate pretreatment agent, restore normal pressure, soak for 15 minutes to fully wet the solution, drain the excess solution, and drain the aggregate until it is saturated and surface dry for later use. S2: Mix silica fume, water and polycarboxylate dispersant and stir at high speed to form a uniform slurry. Let it stand and mature for 1 hour to obtain silica fume composite slurry. Then add redispersible latex powder and stir evenly to obtain micro-nano interface strengthening agent. S3: First, mix the cementitious material, manufactured sand, micro-nano interface reinforcing agent, and 40% of the total water evenly to prepare the core mixture; then add the pretreated aggregate and 20% of the total water and continue to mix evenly to form the first layer of gradient coating; then mix the remaining 40% of the total water and water-reducing agent evenly to adjust the functionality and obtain the mixture. S4: Pour the mixture into a mold, vibrate to shape, cover with plastic film and let stand at room temperature. Finally, remove the mold and transfer to a standard curing room for 7-10 days of curing.
[0011] Furthermore, in step S1, the preheating temperature of the recycled aggregate pretreatment agent is 30-40℃.
[0012] Further, in step S2, the silica fume, water and polycarboxylate dispersant are mixed at 1500 rpm and stirred for 20 minutes.
[0013] Furthermore, in step S3, when preparing the core mixture, stir at 60-70 rpm for 2 minutes; when coating the first layer with gradient, stir at 40-50 rpm for 1 minute; and when adjusting the functionality, stir at 25-35 rpm for 1.5 minutes.
[0014] Furthermore, in step S4, the mixture is covered with a plastic film and left to stand at room temperature for 24 hours. The temperature of the standard curing room is 18-22℃ and the relative humidity is ≥95%.
[0015] The beneficial effects of this invention are as follows: 1. This invention employs a multi-scale interface gradient strengthening mechanism. Lithium silicate reacts with the aggregate surface to generate CSH gel, sealing pores in situ. Pre-hydrated silica fume then fills the micropores in the interface region, optimizing the pore structure. A polymer film then bridges microcracks, reducing the elastic modulus gradient. The invention utilizes a synergistic activation and hydration regulation mechanism. Sodium sulfate provides rapid sulfate activation, promoting early strength development. Alkali slag provides long-lasting alkali activation, fully releasing the activity of steel slag and tailings. Water is added in stages to ensure the activator and active components react at the optimal time. Pore structure optimization is employed. Pretreatment reduces the "initial water absorption peak" of recycled aggregate, while nanoparticles in the interface strengthening agent optimize the slurry packing density, forming a "dense on the outside, sparse on the inside" gradient pore structure, balancing strength and durability.
[0016] 2. In the high-solid-waste green low-carbon concrete system of this invention, the high-solid-waste cementitious materials and recycled aggregates exhibit excellent synergistic effects. The active components in the cementitious materials can undergo secondary hydration reactions with the aggregate surface, strengthening the interfacial transition zone; simultaneously, the microporous structure of the recycled aggregates provides a bearing space for hydration products, forming a denser microstructure. Experimental results show that the compressive strength, flexural strength, and splitting tensile strength of the concrete in this system are significantly higher than those of ordinary recycled concrete, laying a material foundation for its application in high-performance structural engineering.
[0017] 3. Compared to traditional silicate cement, the high-solid-waste cementitious material of this invention avoids the limestone calcination process and significantly reduces clinker usage, resulting in a reduction of carbon emissions by over 80% throughout its entire life cycle. The high-solid-waste green low-carbon concrete prepared based on this cementitious material and recycled aggregates highly aligns with the global trend of low-carbon and green transformation in the construction industry. It also provides an important technical option for green building evaluation standards and low-carbon building material certification systems, with material costs reduced by 15-25% compared to ordinary concrete of the same grade.
[0018] Other advantages, objectives, and features of the invention will be set forth in the following description and will be apparent to those skilled in the art in some respects, or may be learned by practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description
[0019] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration: Figure 1 This is a flowchart illustrating the preparation process of the high-solid-waste green low-carbon concrete of this invention. Detailed Implementation
[0020] like Figure 1 As shown, this invention discloses a high-solid-waste green low-carbon concrete and its preparation method.
[0021] Example 1 S1: After crushing, sorting and washing 625 portions of construction solid waste, place them in a closed pretreatment tank and vacuum them to -0.08 MPa for 10 minutes. Then, extract the pore air and maintain the vacuum state. Pump in lithium silicate solution preheated to 35°C. After restoring normal pressure, soak for 15 minutes to fully wet the aggregate. Then drain the excess solution and drain the aggregate until it is saturated and surface dry for later use. S2: Mix silica fume, water and polycarboxylate dispersant and stir at 1500 rpm for 20 minutes to form a uniform slurry. Let it stand and mature for 1 hour to obtain silica fume composite slurry. Then add 0.75% redispersible latex powder (VAE type) and stir evenly to obtain micro-nano interface strengthening agent. S3: First, mix and stir the cementitious material (composed of steel slag, desulfurized gypsum, mineral powder, metal tailings, and composite activator, totaling 500 parts by weight), 680 parts of manufactured sand, 2 parts of micro-nano interface strengthening agent, and 60 parts of water evenly to prepare the core mixture; then add the pretreated construction solid waste and 30 parts of water and continue stirring evenly to form the first layer of gradient coating; then stir the remaining 60 parts of water and 7 parts of water-reducing agent evenly to adjust the functionality and obtain the mixture. S4: Pour the mixture into a mold, vibrate to form, cover with plastic film and let stand at room temperature for 24 hours. Finally, after demolding, transfer to a standard curing room (temperature 20℃, relative humidity ≥95%) for curing for 10 days.
[0022] Example 2 The raw material components in Example 2 are as follows: steel slag, desulfurized gypsum, mineral powder, metal tailings, composite activator (total weight 450 parts), 600 parts construction solid waste, 690 parts manufactured sand, 3 parts micro-nano interface strengthening agent, recycled aggregate pretreatment agent accounting for 0.75% of construction solid waste; 160 parts water and 6 parts water-reducing agent.
[0023] Its preparation method is exactly the same as that in Example 1.
[0024] Example 3 The raw material components in Example 3 are as follows: steel slag, desulfurized gypsum, mineral powder, metal tailings, and composite activator to form cementitious material (total weight 550 parts), 650 parts construction solid waste, 670 parts manufactured sand, 1.5 parts micro-nano interface strengthening agent, and recycled aggregate pretreatment agent accounting for 0.75% of construction solid waste; total weight 150 parts water and 8 parts water-reducing agent.
[0025] Its preparation method is exactly the same as that in Example 1.
[0026] To verify the superiority of the present invention, comparative examples 1-2 are provided here.
[0027] Comparative Example 1 The raw material components in Comparative Example 1 are as follows: steel slag, desulfurized gypsum, mineral powder, metal tailings, composite activator (total weight 700 parts), 300 parts construction solid waste, 200 parts manufactured sand, 5 parts micro-nano interface strengthening agent, recycled aggregate pretreatment agent accounting for 3% of construction solid waste; 100 parts water and 3 parts water-reducing agent.
[0028] Its preparation method is exactly the same as that in Example 1.
[0029] The concrete prepared in this comparative example has insufficient support strength and is prone to crumbling and collapse.
[0030] Comparative Example 2 Comparative Example 2 uses the same raw materials as Example 1, but all raw materials are mixed and added at once, and the preparation method is different from that of Example 1.
[0031] The concrete prepared in this comparative example has insufficient elasticity and self-shrinkage, making it prone to powdering and collapse.
[0032] The concrete prepared by this invention exhibits significantly improved mechanical properties, with a 28-day compressive strength reaching C40-C50 grade. Compared to traditional recycled aggregate concrete, the interfacial bond strength is increased by 40-60%, the elastic modulus is increased by 15-25%, which helps reduce deformation and significantly improves durability. The chloride ion diffusion coefficient is reduced by 50-70%, the carbonation depth is ≤5mm in the 28-day accelerated carbonation test, the mass loss is ≤5% after frost resistance testing with F200 or higher, the slump is 180-220mm, the 1-hour loss rate is ≤15%, the autogenous shrinkage is reduced by 30-40%, and the drying shrinkage is reduced by 20-30% compared to ordinary recycled concrete.
[0033] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.
Claims
1. A high-solid-waste green low-carbon concrete, characterized in that: The concrete is composed of 450-550 parts of cementitious materials, 1270-1340 parts of aggregate system, 7.3-16.4 parts of functional additives, and 148-168 parts of auxiliary materials; The cementitious material is composed of steel slag, desulfurized gypsum, mineral powder, and metal tailings in a mass ratio of 8:12:30:45, and a composite activator accounting for 5% of the total weight of steel slag, desulfurized gypsum, mineral powder, and metal tailings. The cementitious material is composed of sodium sulfate and solid alkali slag in a mass ratio of 1:
1. The aggregate consists of 600-650 parts of construction solid waste and 670-690 parts of manufactured sand; The functional additives include 1.5-3 parts of micro-nano interface reinforcing agent and 0.5-1% of recycled aggregate pretreatment agent in construction solid waste; the micro-nano interface reinforcing agent is composed of silica fume composite slurry and redispersible latex powder in a mass ratio of 7:3, and the recycled aggregate pretreatment agent is lithium silicate solution. The auxiliary material consists of 140-160 parts water and 6-8 parts water-reducing agent, wherein the water-reducing agent is a polycarboxylate-based water-reducing agent.
2. The high-solid-waste green low-carbon concrete according to claim 1, characterized in that: The steel slag has a particle size ≤45μm, the mineral powder is S95 grade mineral powder, and the metal tailings have a particle size ≤80μm; the manufactured sand has a fineness modulus of 2.3-2.8 and a stone powder content ≤10%, and the construction solid waste has a 5-20mm continuous gradation.
3. The high-solid-waste green low-carbon concrete according to claim 2, characterized in that: The silica fume composite slurry is composed of silica fume, water, and dispersant in a ratio of 100:85:1.5, and has a solid content of 40%.
4. A method for preparing high-solid-waste green low-carbon concrete, using the high-solid-waste green low-carbon concrete as described in any one of claims 1-3, characterized in that: Includes the following steps, S1: Place the construction solid waste in a sealed pretreatment tank and vacuum it to -0.08 MPa for 10 minutes. Then, extract the pore air and maintain the vacuum state. Pump in the preheated recycled aggregate pretreatment agent, restore normal pressure, soak for 15 minutes to fully wet the solution, drain the excess solution, and drain the aggregate until it is saturated and surface dry for later use. S2: Mix silica fume, water and polycarboxylate dispersant and stir at high speed to form a uniform slurry. Let it stand and mature for 1 hour to obtain silica fume composite slurry. Then add redispersible latex powder and stir evenly to obtain micro-nano interface strengthening agent. S3: First, mix the cementitious material, manufactured sand, micro-nano interface reinforcing agent, and 40% of the total water volume evenly to prepare the core mixture; then add the pretreated construction solid waste and 20% of the total water volume and continue to mix evenly to form the first layer of gradient coating; then mix the remaining 40% of the total water volume and water-reducing agent evenly to adjust the functionality and obtain the mixture. S4: Pour the mixture into a mold, vibrate to shape, cover with plastic film and let stand at room temperature. Finally, remove the mold and transfer to a standard curing room for 7-10 days of curing.
5. The method for preparing high-solid-waste green low-carbon concrete according to claim 4, characterized in that: In step S1, the preheating temperature of the recycled aggregate pretreatment agent is 30-40℃.
6. The method for preparing high-solid-waste green low-carbon concrete according to claim 5, characterized in that: In step S2, the silica fume, water and polycarboxylate dispersant are mixed at 1500 rpm and stirred for 20 minutes.
7. The method for preparing high-solid-waste green low-carbon concrete according to claim 6, characterized in that: In step S3, the core mixture is prepared by stirring at 60-70 rpm for 2 minutes; the first layer of gradient coating is prepared by stirring at 40-50 rpm for 1 minute; and the functional adjustment is prepared by stirring at 25-35 rpm for 1.5 minutes.
8. The method for preparing high-solid-waste green low-carbon concrete according to claim 7, characterized in that: In step S4, cover with plastic film and let stand at room temperature for 24 hours. The temperature of the standard curing room is 18-22℃ and the relative humidity is ≥95%.