SAP modified solid waste-based low-carbon concrete and preparation method thereof

Abstract

The invention discloses SAP modified solid waste based low-carbon concrete and a preparation method thereof.The SAP modified solid waste based low-carbon concrete is prepared from, by weight, 0.5-2.5 parts of solid SAP, 76-146 parts of composite steel slag powder, 25-50 parts of an exciting agent, 60-70 parts of fly ash, 187-212 parts of mineral powder, 187-212 parts of cement, 750-772 parts of machine-made medium sand, 900-930 parts of stone, 9.5-9.81 parts of a high-performance water reducing agent and 135-142 parts of water. A nano SAP suspension; wherein the total weight part of the composite steel slag powder, the mineral powder, the fly ash, the exciting agent and the cement is 560-570, and the exciting agent comprises gypsum and silica fume; sAP is a cross-linked polyacrylic acid and acrylamide copolymer. According to the invention, through the internal curing effect of the SAP, the problem of shrinkage cracking of the large-volume multi-source solid waste concrete is effectively solved, and meanwhile, the SAP is utilized to pretreat the coarse aggregate, so that the aggregate-slurry interface structure is improved, and the volume stability and mechanical properties of the concrete are remarkably improved. According to the method, high-added-value resource utilization of the industrial solid waste is achieved, and remarkable low-carbon and environment-friendly benefits are achieved.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, and in particular to an SAP-modified solid waste-based low-carbon concrete and its preparation method. Background Technology

[0002] Concrete is the most widely used and indispensable man-made material in modern infrastructure construction. With the acceleration of global urbanization, the demand for concrete, as a core material in the construction field, has been increasing year by year. At the same time, due to global climate change and the in-depth implementation of the "dual-carbon" strategy, the building materials industry, as a traditional high-carbon industry, faces severe transformation pressure. As the world's most widely used building material, the production process of silicate cement, the core cementitious component of concrete, involves huge resource consumption and greenhouse gas emissions. The carbon emissions generated in its production process account for 8%-10% of global anthropogenic carbon emissions, of which cement clinker production contributes about 60% of carbon emissions.

[0003] Meanwhile, as a major industrial and manufacturing country, my country generates billions of tons of industrial solid waste annually, such as steel slag, mineral slag, and fly ash. The accumulation of these wastes not only occupies land but also poses potential ecological risks to soil and water bodies. Therefore, developing "low-carbon concrete" that uses a large amount of industrial solid waste to replace cement has become an inevitable path for the building materials industry to achieve its "dual-carbon" strategic goals and sustainable development.

[0004] However, the technological evolution of solid waste-based low-carbon concrete faces a core bottleneck: the inherent shrinkage cracking risk of high-volume solid waste cementitious systems. Compared to pure cement systems, solid waste cementitious materials, primarily composed of slag and fly ash, have lower early-stage hydration activity, but can sustain hydration under sufficient moisture conditions. In actual concrete structures, external curing moisture is difficult to penetrate the interior. Unhydrated solid waste particles compete for moisture in the capillaries to sustain hydration, leading to a sharp increase in capillary negative pressure and a significant self-drying effect, which in turn triggers substantial self-shrinkage. This shrinkage begins to develop shortly after the initial setting of the concrete. When the tensile stress generated exceeds the early tensile strength of the concrete, internal microcracks will appear. These microcracks provide a rapid pathway for the intrusion of harmful media such as chloride ions, carbon dioxide, and sulfates, severely degrading the service life of the structure.

[0005] To address these challenges, existing technologies have proposed methods such as strengthening external curing, using shrinkage-reducing agents, and coating coarse aggregates with cement slurry. However, these methods all have limitations: external curing cannot effectively inhibit internal self-drying; shrinkage-reducing agents are expensive and may delay strength development; and aggregate strengthening processes are complex, energy-intensive, and difficult to scale up.

[0006] SAP (Super-absorbent polymer) is a polymer material with extremely high water absorption capacity. For example, Chinese patent application CN202410468504 discloses an impermeable concrete and its preparation method. Existing technologies involve adding liquid SAP and polypropylene fibers to a mixer to prepare wet concrete mix, thereby improving the impermeability of the concrete. However, the above preparation method is not suitable for solid waste-based low-carbon concrete that does not contain polypropylene. Therefore, there is an urgent need for a technology to modify solid waste-based low-carbon concrete using SAP. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this application provides SAP-modified solid waste-based low-carbon concrete and its preparation method, thereby solving technical problems such as high carbon emissions in the concrete production process, easy environmental pollution from solid waste treatment, shrinkage cracking in concrete with large amounts of solid waste, and weak coarse aggregate interface.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] A SAP-modified solid waste-based low-carbon concrete comprises the following raw materials by weight: 0.5-2.5 parts solid SAP, 76-146 parts composite steel slag powder, 25-50 parts activator, 60-70 parts fly ash, 187-212 parts mineral powder, 187-212 parts cement, 750-772 parts manufactured medium sand, 900-930 parts gravel, 9.5-9.81 parts high-performance water-reducing agent, 135-142 parts water, and a ground nano-SAP suspension capable of completely submerging the gravel; wherein the total weight of the composite steel slag powder, mineral powder, fly ash, activator, and cement is 560-570 parts, and the activator includes gypsum and microsilica.

[0010] Both the solid SAP and the ground nano SAP suspension contain cross-linked polyacrylic acid and acrylamide copolymers. The solid SAP has a particle size of 60 μm, a stable liquid absorption ratio of 152.1 g / g in tap water, and a stable liquid absorption ratio of 7.2 g / g in saturated calcium hydroxide solution. Its microstructure consists of broken particles.

[0011] In one embodiment, the nano-SAP suspension is prepared by slowly dispersing nano-sized SAP powder in deionized water under high-speed shear conditions until a uniform, stable, milky-white suspension with a concentration of 0.5% is formed.

[0012] In one embodiment, the composite steel slag powder comprises the following chemical components by mass percentage: 42.44% CaO, 32.1% SiO2, 9.79% Fe2O3 and 8.64% Al2O3.

[0013] In one embodiment, the gypsum is desulfurized gypsum with a particle size of less than 0.074 mm, and the average particle size of the microsilica powder is 0.2 μm.

[0014] In one embodiment, the fly ash is Class II, Category C, and the weight of coarse particles remaining on the fly ash sample after passing through a 45μm square-hole sieve accounts for no more than 2.5% of the total weight of the fly ash.

[0015] In one embodiment, the slag powder is of grade S95 or higher.

[0016] In one embodiment, the cement is silicate cement or ordinary silicate cement, and the strength grade of the cement is greater than or equal to 52.5.

[0017] In one embodiment, the fineness modulus of the sand in the mechanism is 2.0, and the particle size of the gravel is 5-20 mm.

[0018] In one embodiment, the water-reducing agent is a polycarboxylate water-reducing agent, and the water is deionized water.

[0019] This application also provides a method for preparing SAP-modified solid waste-based low-carbon concrete, comprising the following steps:

[0020] S1. Soak 900-930 parts of gravel in a nano-SAP suspension, dry after soaking treatment to obtain pretreated coarse aggregate A;

[0021] S2. Take 0.5-2.5 parts solid SAP, 76-146 parts composite steel slag powder, 25-50 parts activator, 60-70 parts fly ash, 187-212 parts mineral powder, 187-212 parts cement, 750-772 parts manufactured medium sand, 900-930 parts pretreated coarse aggregate A obtained from S1, 9.5-9.81 parts high-performance water-reducing agent, and 135-142 parts water according to the following mass ratio: Mix all materials except water and water-reducing agent evenly under mechanical stirring to obtain dry mix B.

[0022] S3. Dissolve the water-reducing agent in water to obtain water-reducing agent aqueous solution C. Mix the dry mix B with water-reducing agent aqueous solution C under stirring to obtain SAP modified solid waste-based low-carbon concrete mix D.

[0023] S4. Pour SAP-modified solid waste-based low-carbon concrete mix D into a mold for pouring, vibrate and compact, and then cure for 28 days to obtain low-carbon high-performance concrete.

[0024] Compared with the prior art, this application has at least the following beneficial effects:

[0025] This invention innovatively introduces solid SAP into a solid waste-based low-carbon concrete system, constructing a dual-functional mechanism of internal curing and micro-interface strengthening. This addresses, to some extent, the technical challenges of shrinkage cracking and weak coarse aggregate interfaces in concrete with high solid waste content. By uniformly dispersing dried SAP particles within the concrete matrix, these particles absorb some of the mixing water during the mixing stage, forming several evenly distributed micro-reservoirs. During the concrete hardening process, when the internal humidity decreases due to continuous hydration of the cementitious materials, these SAP particles can sense the humidity change and intelligently and slowly provide moisture, achieving in-situ self-curing of the concrete. This internal curing effectively maintains a high-humidity environment within the concrete, significantly reduces capillary negative pressure, inhibits autogenous shrinkage and drying shrinkage, and slows down the formation of early microcracks caused by shrinkage stress, laying a solid foundation for the long-term durability of the concrete.

[0026] This invention, concerning SAP-modified solid waste-based low-carbon concrete, creatively proposes a process for pre-treating coarse aggregate using a nano-SAP suspension. The coarse aggregate is immersed in a nano-scale SAP suspension, causing its surface and internal microcracks to be coated with a SAP functional film. After drying, this forms SAP-modified coarse aggregate. This pre-treatment process endows the coarse aggregate with entirely new functional properties: within the concrete, the SAP functional film on the aggregate surface can absorb moisture from the surrounding paste, creating a localized wet curing microenvironment. This pre-regulates the coarse aggregate's intense water absorption behavior, ensuring the workability of the fresh concrete. More importantly, it continuously provides moisture to the traditionally weak inter-aggregate-paste interface (ITZ), significantly promoting the hydration of cementitious materials at the interface, especially solid wastes such as slag and fly ash. This makes the hydration products in the ITZ region denser, significantly reducing porosity, successfully transforming a weak interface with deteriorated performance into a dense and strengthened interface, thereby greatly improving the overall mechanical properties of the concrete.

[0027] In this invention, SAP (Solid Polymer Acid) forms a precise functional synergy with the solid waste system. The stable endogenous moisture provided by SAP precisely meets the key requirement for the continuous hydration of low-activity solid waste cementitious materials such as high-volume steel slag powder, blast furnace slag powder, and fly ash. Based on the breaking down of the glassy structure of solid waste particles by chemical activators such as gypsum and silica fume, SAP provides a guarantee for the full occurrence of the secondary pozzolanic reaction through physical water supply, promoting the continuous generation of dense CSH gel with a low calcium-to-silica ratio from the solid waste particles and continuously optimizing the microstructure of the slurry. The introduction of SAP, together with the chemical activators, constitutes a dual-drive mode of physical water supply curing and chemical ion activation, producing a synergistic effect. This not only stimulates the potential activity of the solid waste but also achieves continuous growth in concrete strength and durability by promoting long-term hydration.

[0028] The SAP-modified solid waste-based low-carbon concrete provided by this invention has significant advantages such as excellent workability, good mechanical properties and volume stability, environmental friendliness and controllable cost. It successfully integrates solid waste resource utilization, low-carbon concrete and high performance, and provides an innovative and practical technical path to solve the sustainable development problem of the building materials industry.

[0029] The method for preparing SAP-modified solid waste-based low-carbon concrete in this invention has a clear process flow, is simple to construct, and is easy to industrialize in existing ready-mixed concrete production lines. By precisely controlling the SAP dosage, particle size, and pretreatment process of coarse aggregate, low-carbon concrete with excellent workability, good mechanical properties, and high volume stability can be stably prepared. Experimental results show that the SAP-modified solid waste-based low-carbon concrete prepared by this method can maintain an expansion of over 500 mm, a 28-day compressive strength of 75-85 MPa, and a 28-day drying shrinkage value of less than 186 × 10⁻⁶ mm. -6 It has the advantages of good workability, high compressive strength, low drying shrinkage, low cost, environmental protection and pollution-free, and low energy consumption. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below through specific embodiments. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0031] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0032] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various information, such information should not be limited to these terms and should not be construed as indicating or implying relative importance. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0033] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical connection or internal connection between two components. They can be direct connection or indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0034] To better understand the technical solution of the present invention, the present invention will be described in detail below with reference to embodiments and comparative examples.

[0035] Comparative Example 1:

[0036] A solid waste-based low-carbon concrete is obtained by the following preparation steps:

[0037] Step 1: Take 76 parts of composite steel slag powder, 50 parts of activator, 70 parts of fly ash, 187 parts of mineral powder, 187 parts of cement, 772 parts of manufactured medium sand, 930 parts of gravel, 9.81 parts of high-performance water-reducing agent, and 142 parts of water according to the following mass ratios: Mix all materials except water and water-reducing agent evenly under mechanical stirring to obtain dry mix A;

[0038] Step 2: Dissolve the water-reducing agent in water to obtain water-reducing agent aqueous solution B. Mix the dry mix B and water-reducing agent aqueous solution C evenly under stirring to obtain SAP modified solid waste-based low-carbon concrete mix C.

[0039] Step 3: Pour the SAP-modified solid waste-based low-carbon concrete mix C into the mold for pouring, vibrate and compact, and then cure for 28 days to obtain SAP-modified solid waste-based low-carbon concrete.

[0040] Comparative Example 2:

[0041] A SAP-modified solid waste-based low-carbon concrete is obtained by the following preparation steps:

[0042] Step 1: Immerse 930 parts of gravel in a nano-SAP suspension, and dry them after soaking to obtain pretreated coarse aggregate A;

[0043] Step 2: Take 76 parts of composite steel slag powder, 50 parts of activator, 70 parts of fly ash, 187 parts of mineral powder, 187 parts of cement, 772 parts of manufactured medium sand, 930 parts of pretreated coarse aggregate A, 9.81 parts of high-performance water-reducing agent, and 142 parts of water according to the following mass ratios: Mix all materials except water and water-reducing agent evenly under mechanical stirring to obtain dry mix B.

[0044] Step 3: Dissolve the water-reducing agent in water to obtain water-reducing agent aqueous solution C. Mix the dry mix B with water-reducing agent aqueous solution C under stirring to obtain SAP modified solid waste-based low-carbon concrete mix material D.

[0045] Step 4: Pour the SAP-modified solid waste-based low-carbon concrete mix D into the mold for pouring, vibrate and compact, and then cure for 28 days to obtain SAP-modified solid waste-based low-carbon concrete.

[0046] Comparative Example 3:

[0047] A SAP-modified solid waste-based low-carbon concrete is obtained by the following preparation steps:

[0048] Step 1: Take 0.57 parts solid SAP, 76 parts composite steel slag powder, 50 parts activator, 70 parts fly ash, 187 parts mineral powder, 187 parts cement, 772 parts manufactured medium sand, 930 parts gravel, 9.81 parts high-performance water-reducing agent, and 142 parts water according to the following mass ratios; mix all materials except water and water-reducing agent evenly under mechanical stirring to obtain dry mix A;

[0049] Step 2: Dissolve the water-reducing agent in water to obtain water-reducing agent aqueous solution B. Mix the dry mix B and water-reducing agent aqueous solution C evenly under stirring to obtain SAP modified solid waste-based low-carbon concrete mix C.

[0050] Step 3: Pour the SAP-modified solid waste-based low-carbon concrete mix C into the mold for pouring, vibrate and compact, and then cure for 28 days to obtain SAP-modified solid waste-based low-carbon concrete.

[0051] Comparative Example 4:

[0052] A SAP-modified solid waste-based low-carbon concrete is obtained by the following preparation steps:

[0053] Step 1: Take 1.14 parts solid SAP, 76 parts composite steel slag powder, 50 parts activator, 70 parts fly ash, 187 parts mineral powder, 187 parts cement, 772 parts manufactured medium sand, 930 parts gravel, 9.81 parts high-performance water-reducing agent, and 142 parts water according to the following mass ratios; mix all materials except water and water-reducing agent evenly under mechanical stirring to obtain dry mix A;

[0054] Step 2: Dissolve the water-reducing agent in water to obtain water-reducing agent aqueous solution B. Mix the dry mix B and water-reducing agent aqueous solution C evenly under stirring to obtain SAP modified solid waste-based low-carbon concrete mix C.

[0055] Step 3: Pour the SAP-modified solid waste-based low-carbon concrete mix C into the mold for pouring, vibrate and compact, and then cure for 28 days to obtain SAP-modified solid waste-based low-carbon concrete.

[0056] Comparative Example 5:

[0057] Step 1: Take 1.71 parts solid SAP, 76 parts composite steel slag powder, 50 parts activator, 70 parts fly ash, 187 parts mineral powder, 187 parts cement, 772 parts manufactured medium sand, 930 parts gravel, 9.81 parts high-performance water-reducing agent, and 142 parts water according to the following mass ratios; mix all materials except water and water-reducing agent evenly under mechanical stirring to obtain dry mix A;

[0058] Step 2: Dissolve the water-reducing agent in water to obtain water-reducing agent aqueous solution B. Mix the dry mix B and water-reducing agent aqueous solution C evenly under stirring to obtain SAP modified solid waste-based low-carbon concrete mix C.

[0059] Step 3: Pour the SAP-modified solid waste-based low-carbon concrete mix C into the mold for pouring, vibrate and compact, and then cure for 28 days to obtain SAP-modified solid waste-based low-carbon concrete.

[0060] Example 1:

[0061] A SAP-modified solid waste-based low-carbon concrete is obtained by the following preparation steps:

[0062] Step 1: Immerse 930 parts of gravel in a nano-SAP suspension, and dry them after soaking to obtain pretreated coarse aggregate A;

[0063] Step 2: Take 0.57 parts solid SAP, 76 parts composite steel slag powder, 50 parts activator, 70 parts fly ash, 187 parts mineral powder, 187 parts cement, 772 parts manufactured medium sand, 930 parts pretreated coarse aggregate A, 9.81 parts high-performance water-reducing agent, and 142 parts water according to the following mass ratios; mix all materials except water and water-reducing agent evenly under mechanical stirring to obtain dry mix B;

[0064] Step 3: Dissolve the water-reducing agent in water to obtain water-reducing agent aqueous solution C. Mix the dry mix B with water-reducing agent aqueous solution C under stirring to obtain SAP modified solid waste-based low-carbon concrete mix material D.

[0065] Step 4: Pour the SAP-modified solid waste-based low-carbon concrete mix D into the mold for pouring, vibrate and compact, and then cure for 28 days to obtain SAP-modified solid waste-based low-carbon concrete.

[0066] Example 2:

[0067] A SAP-modified solid waste-based low-carbon concrete is obtained by the following preparation steps:

[0068] Step 1: Immerse 930 parts of gravel in a nano-SAP suspension, and dry them after soaking to obtain pretreated coarse aggregate A;

[0069] Step 2: Take 1.14 parts solid SAP, 76 parts composite steel slag powder, 50 parts activator, 70 parts fly ash, 187 parts mineral powder, 187 parts cement, 772 parts manufactured medium sand, 930 parts pretreated coarse aggregate A, 9.81 parts high-performance water-reducing agent, and 142 parts water according to the following mass ratio; mix all materials except water and water-reducing agent evenly under mechanical stirring to obtain dry mix B;

[0070] Step 3: Dissolve the water-reducing agent in water to obtain water-reducing agent aqueous solution C. Mix the dry mix B with water-reducing agent aqueous solution C under stirring to obtain SAP modified solid waste-based low-carbon concrete mix material D.

[0071] Step 4: Pour the SAP-modified solid waste-based low-carbon concrete mix D into the mold for pouring, vibrate and compact, and then cure for 28 days to obtain SAP-modified solid waste-based low-carbon concrete.

[0072] Example 3:

[0073] A SAP-modified solid waste-based low-carbon concrete is obtained by the following preparation steps:

[0074] Step 1: Immerse 930 parts of gravel in a nano-SAP suspension, and dry them after soaking to obtain pretreated coarse aggregate A;

[0075] Step 2: Take 1.71 parts solid SAP, 76 parts composite steel slag powder, 50 parts activator, 70 parts fly ash, 187 parts mineral powder, 187 parts cement, 772 parts manufactured medium sand, 930 parts pretreated coarse aggregate A, 9.81 parts high-performance water-reducing agent, and 142 parts water according to the following mass ratios; mix all materials except water and water-reducing agent evenly under mechanical stirring to obtain dry mix B;

[0076] Step 3: Dissolve the water-reducing agent in water to obtain water-reducing agent aqueous solution C. Mix the dry mix B with water-reducing agent aqueous solution C under stirring to obtain SAP modified solid waste-based low-carbon concrete mix material D.

[0077] Step 4: Pour the SAP-modified solid waste-based low-carbon concrete mix D into the mold for pouring, vibrate and compact, and then cure for 28 days to obtain SAP-modified solid waste-based low-carbon concrete.

[0078] The raw material composition of each embodiment and comparative example is shown in Table 1:

[0079]

[0080] The test results of the high-performance concrete obtained in each embodiment and comparative example are shown in Table 2:

[0081] Table 2:

[0082]

[0083] As can be seen from the data in Tables 1 and 2, the expansion of Comparative Example 1 (without added solid SAP and without pretreated coarse aggregate) is 530 mm, the 28-day compressive strength is 78.2 MPa, and the drying shrinkage value is 513 × 10⁻⁶. -6 Compared to Comparative Example 2 (without SAP but using pretreated coarse aggregate), the expansion was slightly reduced to 520 mm, but the compressive strength increased to 79.9 MPa, and the drying shrinkage was significantly reduced to 371 × 10⁻⁶. -6 This indicates that SAP pretreatment of coarse aggregates can effectively improve the aggregate-slurry interface structure, promote the full hydration of cementitious materials at the interface, thereby enhancing mechanical properties and inhibiting shrinkage.

[0084] Comparative Examples 3 to 5 (untreated coarse aggregate, with solid SAP content of 0.57, 1.14, and 1.71 parts, respectively) show that as the SAP content increases, the spread gradually decreases from 520 mm to 500 mm, the compressive strength first increases from 79.3 MPa (Comparative Example 1) to 83.9 MPa (Comparative Example 4) and then decreases to 76.7 MPa (Comparative Example 5), and the drying shrinkage value decreases from 353 × 10⁻⁶. -6 Significantly reduced to 251×10 -6 This indicates that although the introduction of solid SAP slightly affects workability, it effectively suppresses shrinkage through internal curing, and there exists an optimal dosage (1.14 parts solid SAP, i.e., a dosage of 0.2%) to balance strength and shrinkage performance.

[0085] Examples 1 to 3 (pretreated coarse aggregate, with solid SAP content of 0.57, 1.14, and 1.71 parts, respectively) show that as the solid SAP content increases, the spread gradually decreases from 510 mm to 480 mm, the compressive strength first increases from 81.3 MPa (Example 1) to 85.2 MPa (Example 2) and then decreases to 79.1 MPa (Example 3), and the drying shrinkage value decreases from 186 × 10⁻⁶. -6 Significantly reduced to 134×10 -6 This indicates that SAP and pretreated coarse aggregate have a significant synergistic effect: SAP provides global internal curing, while pretreated coarse aggregate strengthens the interfacial transition zone, jointly promoting the continuous hydration of solid waste cementitious materials, optimizing the microstructure, and thus achieving a balance between high strength and low shrinkage.

[0086] In summary, this invention successfully addresses the shrinkage cracking and interfacial weakness issues in concrete with high solid waste content through SAP modification and coarse aggregate pretreatment. Experimental data shows that SAP-modified solid waste-based low-carbon concrete exhibits optimal performance when pretreated coarse aggregate is used and the solid SAP content is 0.2%. While maintaining good workability, it achieves high compressive strength and low drying shrinkage. Furthermore, by extensively utilizing industrial solid waste such as steel slag and mineral powder, it significantly reduces carbon emissions and resource consumption. This technological approach provides a feasible solution for the low-carbon and high-performance transformation of the building materials industry, possessing significant environmental and economic value.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. An SAP-modified solid waste-based low-carbon concrete, characterized in that, The product comprises, by weight, the following raw materials: 0.5-2.5 parts solid SAP, 76-146 parts composite steel slag powder, 25-50 parts activator, 60-70 parts fly ash, 187-212 parts mineral powder, 187-212 parts cement, 750-772 parts manufactured medium sand, 900-930 parts gravel, 9.5-9.81 parts high-performance water-reducing agent, 135-142 parts water, and a finely ground nano-SAP suspension capable of completely submerging the gravel; wherein the total weight of the composite steel slag powder, mineral powder, fly ash, activator, and cement is 560-570 parts, and the activator includes gypsum and microsilica.

2. The SAP-modified solid waste-based low-carbon concrete according to claim 1, characterized in that, Both the solid SAP and the ground nano SAP suspension contain cross-linked polyacrylic acid and acrylamide copolymers. The solid SAP has a particle size of 60 μm, a stable liquid absorption ratio of 152.1 g / g in tap water, and a stable liquid absorption ratio of 7.2 g / g in saturated calcium hydroxide solution. Its microstructure consists of broken particles.

3. The SAP-modified solid waste-based low-carbon concrete according to claim 1, characterized in that, The nano-SAP suspension is prepared by dispersing nano-sized SAP powder slowly in deionized water under high-speed shear conditions until a uniform, stable, milky-white suspension with a concentration of 0.5% is formed.

4. The SAP-modified solid waste-based low-carbon concrete according to claim 1, characterized in that, The composite steel slag powder comprises the following chemical components by mass percentage: 42.44% CaO, 32.1% SiO2, 9.79% Fe2O3 and 8.64% Al2O3.

5. The SAP-modified solid waste-based low-carbon concrete according to claim 1, characterized in that, The gypsum is desulfurized gypsum with a particle size of less than 0.074 mm, and the average particle size of the microsilica powder is 0.2 μm.

6. The SAP-modified solid waste-based low-carbon concrete according to claim 1, characterized in that, The fly ash is Class II, Category C. When the fly ash sample passes through a 45μm square-hole sieve, the percentage of coarse particles remaining on the sieve accounts for no more than 2.5% of the total weight of the fly ash.

7. The SAP-modified solid waste-based low-carbon concrete according to claim 1, characterized in that, The slag powder is of grade S95 or higher.

8. The SAP-modified solid waste-based low-carbon concrete according to claim 1, characterized in that, The cement is silicate cement or ordinary silicate cement, and the strength grade of the cement is greater than or equal to 52.

5.

9. The SAP-modified solid waste-based low-carbon concrete according to claim 1, characterized in that, The fineness modulus of the sand in the mechanism is 2.0, and the particle size of the gravel is 5-20 mm.

10. The SAP-modified solid waste-based low-carbon concrete according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate water-reducing agent, and the water is deionized water.

11. A method for preparing SAP-modified solid waste-based low-carbon concrete as described in any one of claims 1-0, characterized in that, Includes the following steps: S1. Soak 900-930 parts of gravel in a nano-SAP suspension, dry after soaking treatment to obtain pretreated coarse aggregate A; S2. Take 0.5-2.5 parts solid SAP, 76-146 parts composite steel slag powder, 25-50 parts activator, 60-70 parts fly ash, 187-212 parts mineral powder, 187-212 parts cement, 750-772 parts manufactured medium sand, 900-930 parts pretreated coarse aggregate A obtained from S1, 9.5-9.81 parts high-performance water-reducing agent, and 135-142 parts water according to the following mass ratio: Mix all materials except water and water-reducing agent evenly under mechanical stirring to obtain dry mix B. S3. Dissolve the water-reducing agent in water to obtain water-reducing agent aqueous solution C. Mix the dry mix B with water-reducing agent aqueous solution C under stirring to obtain SAP modified solid waste-based low-carbon concrete mix D. S4. Pour SAP-modified solid waste-based low-carbon concrete mix D into a mold for pouring, vibrate and compact, and then cure for 28 days to obtain low-carbon high-performance concrete.

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