PC component produced by comprehensive utilization of solid waste and preparation method thereof

Abstract

The application belongs to the technical field of building materials, and particularly relates to a PC component produced by comprehensive utilization of solid waste and a preparation method thereof, raw materials of the PC component comprising cementitious material, aggregate, activator and water; the cementitious material is composed of mineral powder, gypsum, silicate cement and dust collected in the processing of hollow extruded cement board (ECP) according to specific proportions. The preparation method comprises: raw material pretreatment and batching, dry mixing, preparation of activator solution, wet mixing, casting forming and curing. The application takes industrial solid waste (mineral powder and gypsum) and internal waste (ECP dust) as main raw materials, realizes efficient resource utilization and internal circulation of the solid waste, and significantly reduces production cost and environmental load. Through alkaline activation and low-temperature steam curing, the prepared non-load-bearing PC component has excellent performance and meets national standards, and has wide environmental protection and economic value.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a PC component produced by comprehensive utilization of solid waste and its preparation method. Background Technology

[0002] With the continuous deepening of industrialization and the rapid advancement of urbanization, the generation of industrial solid waste is showing a rigid growth trend. This includes dozens of types such as mineral powder, desulfurization gypsum, phosphogypsum, fluorogypsum, steel slag, and fly ash. Most of this solid waste is disposed of through open-air stockpiling or landfill, which not only occupies land resources but also easily leads to a series of environmental problems such as soil pollution, groundwater seepage, and dust dispersion. For example, improperly treated gypsum waste can cause soil salinization, while mineral powder dust has become a significant source of PM2.5 pollution in some areas, placing dual pressure on the ecological environment and public health. How to achieve large-scale, high-value-added resource utilization of solid waste has become a core bottleneck restricting the green transformation of industry and a key issue in responding to dual-carbon goals and promoting the development of a circular economy.

[0003] Meanwhile, prefabricated construction, as an important direction for the transformation and upgrading of the construction industry, is being driven by both policy and market forces. As the core load-bearing and enclosure components of prefabricated buildings, the market demand for precast concrete (PC) components has an average annual growth rate exceeding 25%. However, the traditional production model of PC components faces the dual constraints of resource dependence and environmental pressure: its main raw materials are non-renewable resources such as silicate cement and natural sand and gravel. Producing 1 ton of silicate cement requires 1.6 tons of limestone and emits approximately 0.8 tons of carbon dioxide, while the over-exploitation of natural sand and gravel leads to ecological damage problems such as river siltation and landslides. Furthermore, the production of traditional PC components relies on high-grade cement to ensure strength, coupled with the continuous rise in the price of natural sand and gravel, resulting in high production costs and hindering the further promotion of prefabricated buildings.

[0004] Although some research has been conducted on the preparation of building materials using solid waste, most technologies still face significant challenges and have failed to achieve large-scale application. Firstly, the limited amount of solid waste is a core problem: to ensure the mechanical properties of components, existing technologies generally maintain a solid waste content of 30%-50%, and are often limited to a single type of solid waste, such as fly ash or mineral powder. This fails to fully leverage the synergistic effects of multiple solid wastes, resulting in low resource utilization efficiency and failing to fundamentally solve the problem of solid waste accumulation. Secondly, the overall performance of the products is insufficient: existing technologies often unilaterally pursue compressive strength, neglecting key indicators such as durability, crack resistance, and frost resistance required for PC components in actual use scenarios. For example, some components with added solid waste are prone to efflorescence and weathering in humid environments, and their strength loss exceeds 30% after freeze-thaw cycles in low-temperature northern regions, making it difficult to meet the usage requirements of different climatic regions. Third, poor economic efficiency: To compensate for the performance defects caused by solid waste, existing technologies often rely on high-grade cement (such as P·O 52.5 grade) or imported chemical additives, resulting in raw material costs that are 15%-20% higher than traditional PC components. At the same time, some technologies use high-temperature and high-pressure curing processes, which increase energy consumption by more than 50% compared to conventional curing, thus weakening the market competitiveness of the products.

[0005] More importantly, existing technologies fail to achieve internal recycling in building materials production. Most building materials companies generate significant amounts of internal waste during production. For example, dust emissions from hollow extrusion cement board (ECP) processing lines account for approximately 3%-5% of product output. These dust particles are fine and difficult to collect; direct discharge would cause secondary pollution, while outsourcing to third-party treatment incurs high disposal costs. Current solid waste utilization technologies primarily focus on recycling external industrial solid waste, failing to incorporate internal production waste into the resource recovery system, resulting in both resource waste and environmental pressure.

[0006] Against this backdrop, the construction industry urgently needs a PC component production technology that can simultaneously achieve high-proportion solid waste utilization, excellent product performance, low production costs, and internal waste recycling within factories. This technology can not only solve the dual dilemmas of industrial solid waste disposal and prefabricated building development, but also promote the transformation of the building materials industry towards resource recycling, low-carbon production, and high-performance products, possessing significant ecological, economic, and social value.

[0007] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0008] This invention provides a PC component produced by comprehensive utilization of solid waste and its preparation method, aiming to solve the technical problems mentioned in the background art.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows:

[0010] A PC component produced through the comprehensive utilization of solid waste, comprising the following components by weight:

[0011] The cementitious material component comprises 100 parts, including 40-60 parts mineral powder, 10-20 parts gypsum, 10-20 parts silicate cement and 10-20 parts ECP processing dust;

[0012] 150-200 parts aggregate;

[0013] 3-8 parts of alkaline activator;

[0014] 30-45 parts water;

[0015] Additives: 0.5-3 parts.

[0016] Preferably, the gypsum is one of desulfurized gypsum, phosphogypsum, or fluorogypsum.

[0017] Preferably, the aggregate is one or more of natural sand, manufactured sand, or recycled aggregate.

[0018] Preferably, the alkaline activator is one or more of water glass, sodium hydroxide, sodium sulfate, and sodium carbonate.

[0019] Preferably, the additive is one or more of a water-reducing agent, a thickener, or a fiber.

[0020] A method for preparing PC components produced through comprehensive utilization of solid waste, as described above, includes the following steps:

[0021] (a) Ingredients: Weigh each ingredient according to the proportions;

[0022] (b) Dry mixing: Dry mixing of cementitious material components and aggregates to obtain a dry mixture;

[0023] (c) Solution preparation: Dissolve the alkaline activator in water to obtain an activator solution;

[0024] (d) Wet mixing: Add the activator solution to the dry mixture and stir to form a homogeneous mixture;

[0025] (e) Inject the mixture into the mold and vibrate to compact and form the component;

[0026] (f) Curing: The molded components are left to stand for pre-curing, demolded, and then steam cured to obtain the PC components.

[0027] Preferably, in step (b), the dry mixing time is 2-4 minutes.

[0028] Preferably, in step (c), the additive is added to water and dissolved together with the alkaline activator.

[0029] Preferably, in step (d), the wet mixing time is 5-8 minutes.

[0030] Preferably, in step (f), the conditions for static pre-curing are: static curing at room temperature for 12-24 hours; the conditions for steam curing are: temperature 40-60°C, humidity ≥90%, and curing time 24-48 hours.

[0031] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:

[0032] 1. This invention provides a PC component produced by comprehensive utilization of solid waste and its preparation method, with extremely high solid waste utilization rate. In the cementitious material system, mineral powder, gypsum, and ECP dust are all industrial solid wastes, accounting for up to 90% of the total. Through the volcanic ash activity of mineral powder, the sulfate activation effect of gypsum, and the micro-aggregate filling effect of ECP dust, a synergistic mechanism of activity activation, micro-density, and complementary performance is formed, which solves the problem of performance degradation caused by excessive single solid waste content, realizes the transformation of solid waste from passive disposal to active high-value utilization, greatly reduces cement usage, and has significant resource benefits.

[0033] 2. Construct an internal recycling model for building materials production; pioneering a closed-loop system that reuses ECP production line dust for PC component production, achieving closed-loop management and zero emissions of waste within the factory, solving the problem of dust treatment and reducing overall production costs, providing building materials companies with an integrated solution for waste resource utilization, production cost reduction and environmental compliance, which can be replicated and promoted to similar building materials production companies such as aerated concrete and precast components, driving the industry to transform from a linear production model of raw materials, products and waste to resource recycling.

[0034] 3. Through the synergistic effect of alkaline activators and mineral powder and gypsum systems, a large amount of hydrated calcium silicate (CSH) gel and ettringite (AFt) crystals are induced to form a dense and uniform microstructure, which makes the compressive strength of PC components stable at over 35MPa after 28 days, and can reach up to 41.5MPa, far exceeding the requirement of ≥30MPa in the national standard GB / T 23451-2023; the drying shrinkage value is controlled at 0.29-0.38mm / m, which is far below the national standard limit of ≤0.6mm / m, effectively solving the pain point of drying shrinkage cracking of traditional solid waste building materials, and improving the integrity and safety of the components after installation.

[0035] 4. The core raw materials are inexpensive industrial solid waste and internal waste. The procurement cost of mineral powder and gypsum is much lower than that of silicate cement. ECP dust does not require additional procurement and saves disposal costs, which effectively reduces the raw material cost compared with traditional PC components. Low-temperature steam curing is adopted, which reduces energy consumption compared with traditional high-temperature and high-pressure curing, significantly reducing production costs and making it highly competitive in the market. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] The technical solution of the present invention is described in detail below through three embodiments, and three comparative examples are set to verify the advantages of the present invention. All performance tests are carried out in accordance with the national standard GB / T 23451-2023 Lightweight partition wall panels for building. The core test indicators include 28-day compressive strength, drying shrinkage value, softening coefficient, and strength loss rate after freeze-thaw cycles (25 times), as detailed below:

[0038] I. Raw Materials and Equipment Description

[0039] 1. Basic raw materials

[0040] Mineral powder: S95 grade, specific surface area 420m² / kg;

[0041] Gypsum: Desulfurized gypsum, phosphogypsum, moisture content ≤5%;

[0042] Silicate cement: P·O 42.5 grade;

[0043] ECP dust: Collected from our ECP production line, it undergoes impurity removal and drying treatment, with a particle size ≤0.075mm;

[0044] Aggregates: natural sand (fineness modulus 2.6), manufactured sand (fineness modulus 2.8), recycled aggregate (particle size 5-10mm, crushing value ≤16%).

[0045] Activators: water glass (modulus 2.4), sodium hydroxide (industrial grade, purity ≥96%), sodium sulfate (industrial grade, purity ≥98%).

[0046] Additives: Polycarboxylate superplasticizer (40% solids content), hydroxypropyl methylcellulose (thickener), polypropylene fiber (6mm length);

[0047] Water: tap water.

[0048] 2. Preparation equipment

[0049] Planetary mixer, special mold for PC components, vibration table, constant temperature and humidity curing kiln.

[0050] II. Example Design (by weight, 1 part = 10 kg / m³)

[0051] Example 1

[0052] Cementitious materials 100; including mineral powder 50, desulfurized gypsum 15, silicate cement 10, and ECP dust 25;

[0053] Aggregate (natural sand) 170;

[0054] Activator (sodium hydroxide) 5;

[0055] Water 38;

[0056] Additive (hydroxypropyl methylcellulose) 1.2;

[0057] The preparation method of PC components includes the following steps:

[0058] (a) Ingredients: Weigh each ingredient according to the proportions;

[0059] (b) Mineral powder, gypsum, cement, ECP dust, and natural sand are added to a planetary mixer and dry-mixed for 3 minutes;

[0060] (c) Preparation of solution: Dissolve sodium hydroxide in water to obtain an activator solution;

[0061] (d) Add the activator solution to the mixer and wet mix for 6 minutes to obtain a homogeneous mixture;

[0062] (e) Inject the mixture into the mold and vibrate to compact and form the component;

[0063] (f) Curing: After molding, the component is left to stand for 20 hours for pre-curing, then demolded, and then steam cured at 55°C and 92% humidity for 36 hours to obtain the PC component.

[0064] Example 2

[0065] Cementitious materials 100; including mineral powder 60, desulfurized gypsum 10, silicate cement 10, and ECP dust 20;

[0066] Aggregate (recycled aggregate) 160;

[0067] Activator (sodium sulfate) 6;

[0068] Water 42;

[0069] Additive (polypropylene fiber) 1.2;

[0070] The preparation method of PC components includes the following steps:

[0071] (a) Ingredients: Weigh each ingredient according to the proportions;

[0072] (b) Mineral powder, gypsum, cement, ECP dust, and natural sand are added to a planetary mixer and dry-mixed for 4 minutes;

[0073] (c) Preparation of solution: Dissolve sodium sulfate in water to obtain an activator solution;

[0074] (d) Add the activator solution to the mixer and wet mix for 8 minutes to obtain a homogeneous mixture;

[0075] (e) Inject the mixture into the mold and vibrate to compact and form the component;

[0076] (f) Curing: After molding, the component is left to stand for 24 hours for pre-curing, then demolded, and then steam cured at 60°C and 95% humidity for 40 hours to obtain the PC component.

[0077] Example 3

[0078] Cementitious materials 100; including mineral powder 40, desulfurized gypsum 20, silicate cement 20, and ECP dust 20;

[0079] Aggregate (95% natural sand + 95% manufactured sand) 190;

[0080] Activator (water glass 4 + sodium carbonate 3) 7;

[0081] Water 35;

[0082] Additives (polycarboxylate superplasticizer 1.0 + polypropylene fiber 1.0) 2.0;

[0083] The preparation method of PC components includes the following steps:

[0084] (a) Ingredients: Weigh each ingredient according to the proportions;

[0085] (b) Mineral powder, gypsum, cement, ECP dust, and natural sand are added to a planetary mixer and dry-mixed for 2.5 minutes;

[0086] (c) Solution preparation: Dissolve water glass and sodium carbonate in water to obtain an activator solution;

[0087] (d) Add the activator solution to the mixer and wet mix for 5 minutes to obtain a homogeneous mixture;

[0088] (e) Inject the mixture into the mold and vibrate to compact and form the component;

[0089] (f) Curing: After molding, the component is left to stand for 16 hours for pre-curing, then demolded, and then steam cured at 45°C and 90% humidity for 48 hours to obtain the PC component.

[0090] III. Proportional Design (by weight, 1 part = 10 kg / m³)

[0091] Comparative Example 1

[0092] The cementitious material 100 contains 50 parts mineral powder, 15 parts desulfurized gypsum, and 35 parts silicate cement, and is free of ECP dust; the rest is the same as in Example 1.

[0093] Comparative Example 2

[0094] No activator was added; otherwise, it was the same as in Example 2.

[0095] Comparative Example 3 (using traditional proportions and high-temperature curing, with low solid waste content)

[0096] 100% cementitious material; including 20% ​​mineral powder, 10% desulfurized gypsum, and 70% silicate cement, with no ECP dust;

[0097] Aggregate (natural sand) 180;

[0098] Activator 0;

[0099] Water 45;

[0100] Additive (polycarboxylate superplasticizer) 0.8;

[0101] The preparation method of PC components includes the following steps:

[0102] (a) Ingredients: Weigh each ingredient according to the proportions;

[0103] (b) Mineral powder, gypsum, cement, ECP dust and natural sand are put into a planetary mixer, dry-mixed for 3 minutes, then wet-mixed for 5 minutes to obtain a uniform mixture.

[0104] (c) Inject the mixture into the mold and vibrate to compact and form the component;

[0105] (d) Curing: After molding, the component is left to stand for 12 hours for pre-curing, then demolded, and then steam cured at 80°C and 90% humidity for 24 hours to obtain the PC component.

[0106] IV. Comparison of Performance Test Results with National Standards

[0107] The performance test results are compared with the national standard in Table 1:

[0108] Table 1

[0109] Group 28-day compressive strength (MPa) Drying shrinkage value (mm / m) Softening coefficient Strength loss rate after freeze-thaw cycle (%) Solid waste content (in cementitious materials) National Standard Requirements ≥30 ≤0.6 ≥0.8 ≤20 - Example 1 38.6 0.32 0.89 12.5 90% Example 2 36.2 0.35 0.86 14.8 90% Example 3 41.5 0.29 0.92 10.3 80% Comparative Example 1 34.1 0.58 0.83 65% Comparative Example 2 27.5 0.72 0.76 25.7 90% Comparative Example 3 39.8 0.30 0.90 11.6 30%

[0110] V. Results Analysis

[0111] 1. Validation of the advantages of the implementation examples

[0112] The core performance of Examples 1-3 far exceeds the national standard requirements. Among them, Example 3 performs the best, with a compressive strength of 41.5 MPa and a drying shrinkage of only 0.29 mm / m. This is due to the synergistic effect of mineral powder, gypsum and composite activator, which forms a dense CSH gel and ettringite (AFt) composite structure. At the same time, the filling effect of ECP dust further optimizes the micropores.

[0113] 2. Conclusions based on comparative proportions

[0114] In Comparative Example 1 (without ECP dust), the solid waste utilization rate dropped to 65%, and the drying shrinkage value was close to the national standard limit, proving that the closed-loop utilization of ECP dust not only improves resource efficiency but also improves volume stability.

[0115] In Comparative Example 2 (without activator), due to the lack of alkaline activation, the solid waste hydration reaction was insufficient, the compressive strength was only 27.5 MPa, which is lower than the national standard requirement of 30 MPa, and the drying shrinkage and freeze resistance were also substandard, highlighting the key role of activator in activating the activity of solid waste.

[0116] In Comparative Example 3 (traditional formulation), although the performance met the standards, the solid waste content was only 30%, and the energy consumption of high-temperature curing was more than 40% higher than that of the low-temperature curing of this invention. Its economic and environmental performance was significantly inferior to that of this invention.

[0117] This invention, through a combination of high-proportion solid waste co-processing, internal dust circulation, alkaline activation, and low-temperature curing, significantly reduces raw material costs and energy consumption while ensuring the performance of PC components meets standards, thus aligning with the green development trend of prefabricated buildings.

[0118] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should fall within the patent scope covered by the present invention.

Claims

1. A PC component produced through comprehensive utilization of solid waste, characterized in that, By weight, it includes the following components: The cementitious material component comprises 100 parts, including 40-60 parts mineral powder, 10-20 parts gypsum, 10-20 parts silicate cement and 10-20 parts ECP processing dust; 150-200 parts aggregate; 3-8 parts of alkaline activator; 30-45 parts water; Additives: 0.5-3 parts.

2. The PC component produced by comprehensive utilization of solid waste as described in claim 1, characterized in that, The gypsum is one of desulfurized gypsum, phosphogypsum, or fluorogypsum.

3. The PC component produced by comprehensive utilization of solid waste as described in claim 1, characterized in that, The aggregate is one or more of natural sand, manufactured sand, or recycled aggregate.

4. The PC component produced by comprehensive utilization of solid waste as described in claim 1, characterized in that, The alkaline activator is one or more of water glass, sodium hydroxide, sodium sulfate, and sodium carbonate.

5. A PC component produced through comprehensive utilization of solid waste as described in claim 1, characterized in that, The additive is one or more of a water-reducing agent, a thickener, or a fiber.

6. A method for preparing PC components produced by comprehensive utilization of solid waste as described in any one of claims 1-5, characterized in that, Includes the following steps: (a) Ingredients: Weigh each ingredient according to the proportions; (b) Dry mixing: Dry mixing of cementitious material components and aggregates to obtain a dry mixture; (c) Solution preparation: Dissolve the alkaline activator in water to obtain an activator solution; (d) Wet mixing: Add the activator solution to the dry mixture and stir to form a homogeneous mixture; (e) Inject the mixture into the mold and vibrate to compact and form the component; (f) Curing: The molded components are left to stand for pre-curing, demolded, and then steam cured to obtain the PC components.

7. The method for preparing PC components produced through comprehensive utilization of solid waste as described in claim 6, characterized in that, In step (b), the dry mixing time is 2-4 minutes.

8. The method for preparing PC components produced through comprehensive utilization of solid waste as described in claim 6, characterized in that, In step (c), the additive is added to water and dissolved together with the alkaline activator.

9. The method for preparing PC components produced through comprehensive utilization of solid waste as described in claim 6, characterized in that, In step (d), the wet mixing time is 5-8 minutes.

10. The method for preparing PC components produced through comprehensive utilization of solid waste as described in claim 6, characterized in that, In step (f), the conditions for static pre-curing are: static curing at room temperature for 12-24 hours; the conditions for steam curing are: temperature 40-60°C, humidity ≥90%, and curing time 24-48 hours.