Port interlocking block based on collaborative solid waste and low-temperature preparation process thereof

Abstract

The invention relates to the technical field of building material preparation, and discloses a port interlocking block based on synergetic solid waste and a low-temperature preparation process thereof, the raw materials comprise Bayer process red mud powder, carbide slag powder, blast furnace slag micropowder, a composite excitation liquid and aged steel slag aggregate. The process comprises the following steps: carrying out thermal-chemical pre-activation pulping on the red mud by utilizing reaction heat of excitation liquid and calcium-based solid waste; adding slag to prepare gelled slurry and wrapping the aggregate; and after vibration molding, magnesium-chlorine moisture absorption circulating low-temperature curing is performed in a constant-temperature and constant-humidity environment. The activity of the raw materials is excited through multi-element solid waste synergism and thermal activation, ion enrichment and crystallization are driven through unsaturated humidity difference, Friedel salt and magnesium-based products are generated through induction to compactly fill pores, and the problems that red mud-based materials are low in early strength, high in energy consumption and poor in seawater corrosion resistance are solved. And low-energy-consumption rapid preparation of the interlocking block with high strength, excellent volume stability and corrosion resistance is realized.

Description

Technical Field

[0001] This invention relates to the field of building material preparation technology, specifically to a port interlocking block based on synergistic solid waste and its low-temperature preparation process. Background Technology

[0002] Port infrastructure construction demands massive amounts of paving materials, and utilizing industrial solid waste to prepare interlocking blocks aligns with the trend of green and low-carbon development. Bayer process red mud, carbide slag, and steel slag are typical bulk industrial solid wastes, with huge reserves and heavy environmental burdens. The main mineral components of red mud have a stable structure, making it difficult to release potential activity. Conventional cementitious systems cannot achieve high-volume red mud utilization, resulting in low mechanical properties of the products. Although high-temperature sintering processes can improve the performance of red mud-based materials, excessive energy consumption not only increases production costs but also violates the principles of energy conservation and emission reduction. In traditional non-fired brick preparation processes, the long room-temperature curing period and slow hydration process of the cementitious materials lead to delayed early strength development, affecting production efficiency.

[0003] The marine service environment is characterized by high salinity corrosion and alternating wet and dry conditions, posing severe challenges to material durability. Ordinary concrete interlocking blocks contain numerous interconnected pores, which cannot effectively prevent chloride ion penetration from seawater, easily leading to structural deterioration and strength reduction. Traditional cementitious systems undergo chemical and drying shrinkage during hardening, easily inducing microcracks within the matrix. These cracks become channels for the inward transmission of corrosive media, further exacerbating material damage. While steel slag aggregate possesses high strength and wear resistance, its inherent stability is difficult to control, easily causing volume expansion and failure in the later stages of product fabrication. Currently, there is a lack of interlocking block preparation technology that can simultaneously achieve synergistic activation of recalcitrant solid wastes such as red mud and rapidly obtain high strength, seawater corrosion resistance, and volumetric stability under low-temperature conditions. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a port interlocking block based on synergistic solid waste and its low-temperature preparation process. This solves the problems of low early strength of products due to the difficulty in activating the potential activity of existing red mud-based solid waste materials, high energy consumption of traditional high-temperature preparation processes, weak resistance to chloride ion penetration of ordinary interlocking blocks, poor volume stability due to shrinkage deformation, and poor resistance to seawater erosion.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: a port interlocking block based on collaborative solid waste and its low-temperature preparation process.

[0006] In a first aspect, the present invention provides a port interlocking block based on collaborative solid waste, employing the following technical solution: A port interlocking block based on co-processed solid waste is made from the following raw materials in parts by weight: 25-35 parts Bayer red mud powder; 10-20 parts calcium carbide slag powder; 45-65 parts blast furnace slag powder; 28-34 parts composite activating liquid; 100-175 parts aged steel slag coarse aggregate; and 150-175 parts aged steel slag fine aggregate.

[0007] By adopting the above technical solution, a port interlocking block with high early strength, excellent volume stability and resistance to seawater erosion was obtained by using a multi-component solid waste cementing system composed of Bayer red mud powder, calcium carbide slag powder and blast furnace slag powder, combined with a specific composite activating liquid and all-steel slag aggregate.

[0008] Specifically, the innovative mechanism and beneficial effects of this invention are mainly reflected in the following reaction process and structural evolution: First, a calcium-aluminum-silicon-rich alkaline dissolution environment was constructed. Calcium carbide slag powder, as the main alkaline activation source, provided a high concentration of hydroxide ions, effectively disrupting the glassy structure on the surface of blast furnace slag powder and Bayer red mud powder, promoting the dissolution and release of silicon and aluminum components, and providing sufficient precursors for subsequent hydration reactions.

[0009] Secondly, the chemical solidification and pore filling of chloride ions (Friedel salt effect) were achieved. The high concentration of chloride ions introduced by the composite activating solution did not merely exist as a physical component, but rather underwent a specific chemical reaction with active aluminate ions released from Bayer process red mud powder and slag, as well as calcium ions in the system. This reaction preferentially generated insoluble Friedel salts. Friedel salts exhibit a layered crystalline structure and are formed in situ within the micropores of the cementitious material. This not only effectively fills the matrix pores and reduces porosity, but also converts free chloride ions from the external environment or the activator into a chemically bound state, significantly improving the material's resistance to chloride ion penetration and seawater erosion.

[0010] Third, a densification and enhancement mechanism for magnesium-based products was established. In the alkaline environment created by carbide slag, magnesium ions in the composite activating solution rapidly undergo a precipitation reaction to generate magnesium hydroxide or magnesium-based oxychloride hydrates. These fine magnesium-based precipitates act as micro-aggregates, further filling the nanoscale pores between calcium silicate hydrate (CSH) gels, forming a synergistic filling effect with Friedel salt, significantly improving the density and mechanical strength of the matrix.

[0011] Fourth, interface strengthening of all-steel slag aggregate. Using aged steel slag as coarse and fine aggregate, since steel slag itself contains calcium silicate mineral phases similar to cementitious matrix, the two can form chemical bonds rather than simple physical interlocking in the interfacial transition zone (ITZ), eliminating the weak links of aggregate interface in traditional concrete, resulting in higher overall strength and better wear resistance of interlocking blocks.

[0012] Preferably, the composite activating solution is a mixed aqueous solution of calcium chloride and magnesium chloride; based on a total weight of 100 parts of the composite activating solution, the total weight of calcium chloride and magnesium chloride is 22.0-28.0 parts; and the molar ratio of magnesium ions to calcium ions in the solution is 0.15-0.35.

[0013] By adopting the above technical solution, not only is the total salinity of the activator limited to ensure sufficient hydrated ion concentration, but more importantly, the magnesium-calcium molar ratio is precisely controlled.

[0014] First, the total salinity is controlled at 22.0-28.0 parts to ensure that the solution has appropriate ionic strength, which can quickly activate the activity of solid waste and avoid salting out or crystal expansion damage caused by excessive salinity.

[0015] Secondly, controlling the magnesium content within the range of 0.15-0.35 is crucial for balancing early strength and volumetric stability. An appropriate amount of magnesium ions can generate micro-expanding magnesium-containing hydrates, effectively compensating for chemical shrinkage during the hardening process of cementitious materials. Excessive magnesium content leads to later expansion and cracking, while insufficient content fails to provide densification and shrinkage compensation. This specific ratio ensures that the formation rate of Friedel salt matches the filling rate of the magnesium-based product, resulting in a defect-free microstructure.

[0016] Preferably, the particle size of the aged steel slag coarse aggregate is 4.75mm-9.5mm, the particle size of the aged steel slag fine aggregate is 0mm-4.75mm, and when preparing interlocking blocks, the mass ratio of the total amount of cementitious material to the total amount of aggregate is controlled between 1:2.5 and 1:3.5.

[0017] By adopting the above technical solution, a high-strength aggregate skeleton is constructed based on the principle of closest packing by combining discontinuous gradation (coarse aggregate) and continuous gradation (fine aggregate). The mass ratio of cementitious material to aggregate is controlled at 1:2.5-1:3.5, ensuring that the cementitious paste can fully coat each particle size of steel slag aggregate, and that there is an appropriate amount of excess paste to fill the voids in the skeleton. This avoids both the structural looseness caused by insufficient paste and the shrinkage risk caused by excessive paste, thereby achieving optimal mechanical properties and economic benefits.

[0018] Preferably, Bayer red mud powder, carbide slag powder and blast furnace slag powder together constitute a cementing system. The cementing system is activated by a composite activating liquid and reacts with the aluminum phase in the solid waste to generate Friedel salt and magnesium-based hydration products to fill the pores.

[0019] By adopting the above technical solution, the phase composition of the material's microstructure was clarified. This technical solution utilizes the aluminum component, which is usually considered a waste impurity in Bayer process red mud, as the core reactant, transforming it into Friedel salt crystals with reinforcing and toughening effects. This "waste-to-waste" reaction path not only solves the utilization problem of red mud but also directly constructs a chemically bonded anti-erosion barrier, giving the interlocking block far superior durability in marine environments compared to ordinary silicate cement products.

[0020] Secondly, the present invention provides a low-temperature preparation process for port interlocking blocks based on synergistic solid waste, employing the following technical solution: A low-temperature preparation process for port interlocking blocks based on synergistic solid waste, used to prepare the port interlocking blocks mentioned in the first aspect above, includes the following steps: S1. Thermo-chemical pre-activation pulping: Bayer red mud powder and carbide slag powder are placed in a mixer, and a composite activating liquid is added and stirred. The reaction heat released by solid-liquid contact is used to increase the temperature of the pulp and complete the pre-activation of the cementitious components to obtain activated pulp. S2. Preparation of gelling slurry: Add blast furnace slag powder to the activated slurry obtained in step S1, increase the stirring speed for secondary stirring, and form a uniform gelling slurry. S3. Preparation of molding material: The aged steel slag coarse aggregate and aged steel slag fine aggregate are premixed evenly, and then added to the uniform gel slurry obtained in step S2. Stirring is maintained until the slurry fully coats the surface of the aggregate to obtain molding material. S4. Vibration molding: The molding material is injected into the interlocking block mold and a green blank is formed under the combined action of vibration and pressure. S5. Low-temperature curing: The green body and mold are placed in a constant temperature and humidity environment for magnesium-chlorine moisture absorption cycle curing. The humidity difference caused by the unsaturated humidity environment drives the migration of moisture and the enrichment and precipitation of ions, promoting early strength establishment. S6. Demolding and Aging: After the curing in step S5 is completed, demold the product and place it in a naturally ventilated environment for aging to obtain the finished product.

[0021] By adopting the above technical solution, this invention does not employ traditional room temperature curing or high temperature autoclaving, but creatively develops a "stepwise pulping-low temperature wet heat cycle" process. This process achieves the maximum release of activity and rapid construction of structure in solid waste materials through a reaction mechanism in the form of the following steps: The first step is thermo-chemical coupling pre-activation. In stage S1, the rapid exothermic reaction that occurs when carbide slag (mainly calcium hydroxide) comes into contact with the composite activating liquid (high concentration of magnesium chloride / calcium chloride) creates an immediate localized temperature rise environment inside the mixer. This endogenous heat directly acts on the Bayer process red mud powder, which is difficult to activate, causing the inert alumina shell on its surface to depolymerize under the dual attack of heat and chloride ions, exposing internal active sites and reserving a highly active aluminum source for subsequent reactions.

[0022] The second step involves the graded control of rheological properties and reaction rate. Adding blast furnace slag powder after stage S2 is to prevent premature reaction of the slag in the high-temperature, high-alkali environment of S1, which could lead to "false setting" or loss of fluidity. This step-by-step feeding ensures that the slurry maintains optimal thixotropy and fluidity during the aggregate coating and vibration molding stages, allowing the high-solids-content molding material to tightly fill the mold.

[0023] The third step is unsaturated humidity-driven crystallization and densification. In stage S5, the core of the process lies in establishing a "magnesium-chlorine hygroscopic cycle" mechanism. Under a constant temperature and humidity unsaturated environment, moisture inside the green body tends to migrate outwards, causing the ion concentration in the pore solution to rapidly reach a supersaturated state. This supersaturation drives the explosive nucleation and growth of Friedel salts and magnesium-based hydration products. Simultaneously, because the system contains highly hygroscopic calcium chloride and magnesium chloride, these salts can capture necessary moisture from the environment to prevent matrix cracking and maintain the continuous hydration reaction. This dynamic equilibrium mechanism significantly accelerates the establishment of early strength, allowing the product to be demolded in a short time.

[0024] Preferably, in step S1, the stirring speed is controlled at 120-180 r / min, the stirring time is 3-5 minutes, and the slurry temperature is controlled to rise naturally by at least 5°C from room temperature to complete the pre-activation; in step S2, the stirring speed is increased to 250-300 r / min, and the stirring time is 2-3 minutes; in step S3, the same stirring speed as in S2 is maintained and stirring continues for 2-3 minutes.

[0025] By adopting the above technical solution, the kinetic requirements of different reaction stages were precisely matched.

[0026] S1 employs low-speed, long-duration stirring to extend the solid-liquid contact time, accumulate reaction heat, ensure sufficient wetting and initial depolymerization of sparingly soluble components, and avoid heat loss due to slurry splashing.

[0027] S2 and S3 employ high-speed, high-shear mixing. The purpose is to break up the agglomeration of cementitious particles by using mechanical shear force after the slurry viscosity increases, and to force the slurry to overcome the roughness of the steel slag aggregate surface under high kinetic energy, thereby achieving penetration and encapsulation of the aggregate micropores and significantly improving the interfacial bonding strength.

[0028] Preferably, in step S4, the vibration frequency is 50-60Hz, the molding pressure is 15-20MPa, and the vibration pressing time is 5-10 seconds.

[0029] By adopting the above technical solution, high-frequency vibration is used to liquefy the dry and hard cementitious mixture, expel internal air bubbles, and high molding pressure forces the particles to rearrange and achieve the most compact packing state, ensuring that the green body has extremely high initial density, laying the physical basis for subsequent high strength indicators.

[0030] Preferably, in step S5, the temperature for low-temperature curing is set to 50-60℃, the relative humidity is set to 75%-85%, and the curing time is 12-24 hours; in step S6, the storage and aging time is 3-7 days.

[0031] By adopting the above technical solution, the optimal thermodynamic window for the "magnesium-chlorine hygroscopic cycle" was defined.

[0032] If the temperature is below 50℃ or the humidity is above 85% (close to saturation), the driving force for water evaporation is insufficient, ion enrichment is slow, and early intensity establishment is delayed.

[0033] If the temperature is above 60℃ or the humidity is below 75%, the moisture will be lost too quickly, and the cementitious material will dry before it has time to hydrate, which will cause the surface of the product to powder or crack.

[0034] By precisely locking the relative humidity at 75%-85%, which is close to the equilibrium relative humidity of chloride solutions, a dynamic balance of "micro-dehydration-micro-hygroscopicity" is maintained using vapor pressure difference. This allows for the achievement of excellent mechanical properties in just 12-24 hours without consuming large amounts of external energy (such as high-temperature steam pressure). The S6 aging process further releases the crystallization stress inside the product, ensuring long-term volume stability.

[0035] This invention provides a port interlocking block based on synergistic solid waste and its low-temperature preparation process. It has the following beneficial effects: 1. This invention constructs a multi-component solid waste cementing system using Bayer red mud powder, calcium carbide slag powder, and blast furnace slag micro powder. Combined with a composite activating liquid composed of calcium chloride and magnesium chloride, the hydration process is regulated by a specific ratio of magnesium and calcium ions. This induces the reaction to generate Friedel salt and magnesium-based precipitates that fill the pores of the matrix in situ, thereby achieving rapid densification of the cementing structure. As a result, high compressive strength that meets engineering requirements can be obtained under low-temperature curing conditions.

[0036] 2. This invention generates layered Friedel salt by reacting high concentrations of chloride ions in the activating liquid with the aluminum phase in solid waste, converting free chloride ions into a chemically bound state and constructing a chloride ion penetration barrier. At the same time, it utilizes the micro-expansion characteristics generated by magnesium ion hydration to compensate for the chemical shrinkage of the cementitious material, effectively inhibiting the generation of microcracks and improving the corrosion resistance and volume stability of the interlocking block in a marine environment.

[0037] 3. This invention utilizes the heat of reaction to activate red mud through a thermochemical pre-activation pulping process, and combines it with magnesium chloride moisture absorption circulation low-temperature curing technology under constant temperature and humidity conditions. By using unsaturated humidity difference to drive water migration and ion enrichment, the crystal growth of hydration products is accelerated, and the strength of solid waste cementitious materials is rapidly established under low energy consumption conditions, thus shortening the production cycle. Detailed Implementation

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Preparation Examples 1-3: Preparation Example 1: This preparation example demonstrates the preparation of a low-concentration, low-magnesium-to-calcium-ion composite activation solution. 195.0 parts of anhydrous calcium chloride and 25.0 parts of anhydrous magnesium chloride were weighed and added to a stirred container containing 780.0 parts of water. The mixture was stirred at 300 r / min for 5 minutes at room temperature until all the solids were dissolved, resulting in a clear composite activation solution with a total salinity mass fraction of 0.22 and a magnesium ion to calcium ion molar ratio of 0.15.

[0040] Preparation Example 2: Weigh 206.0 parts of anhydrous calcium chloride and 44.0 parts of anhydrous magnesium chloride, add them to a stirring container containing 750.0 parts of water, and stir at 300 r / min for 5 minutes at room temperature until the solids are completely dissolved to obtain a clear composite activating solution with a total salinity mass fraction of 0.25 and a molar ratio of magnesium ions to calcium ions of 0.25.

[0041] Preparation Example 3: Weigh 215.4 parts of anhydrous calcium chloride and 64.6 parts of anhydrous magnesium chloride, add them to a stirring container containing 720.0 parts of water, and stir at 300 r / min for 5 minutes at room temperature until the solids are completely dissolved to obtain a clear composite activating solution with a total salinity mass fraction of 0.28 and a molar ratio of magnesium ions to calcium ions of 0.35.

[0042] Examples 1-3: Example 1: This embodiment provides a port interlocking block based on synergistic solid waste and its low-temperature preparation process, specifically including the following steps: First, weigh 25.0 parts of Bayer process red mud powder and 10.0 parts of calcium carbide slag powder and place them in a forced mixer. Add 28.0 parts of the composite activation liquid obtained in Preparation Example 1 (liquid-to-gel ratio of 0.28). Turn on the mixer and stir at 120 r / min for 5 minutes. During this period, the reaction heat released by the solid-liquid contact is used for pre-activation. After the slurry temperature naturally rises by about 5°C from room temperature, the thermo-chemical pre-activation slurry preparation is completed.

[0043] Subsequently, 65.0 parts of blast furnace slag powder were added to the activated slurry, and the mixer speed was increased to 250 r / min and stirred for 3 minutes to form a uniform gel slurry. Then, 100.0 parts of pre-mixed aged steel slag coarse aggregate (particle size 4.75mm-9.5mm) and 150.0 parts of aged steel slag fine aggregate (particle size 0mm-4.75mm) were added (the mortar-to-aggregate ratio was 1:2.5), and the mixture was stirred at high speed for another 3 minutes to ensure that the slurry fully coated the surface of the aggregate, resulting in a uniformly mixed molding material.

[0044] The molding material is injected into the interlocking block mold and vibrated and pressed for 10 seconds at a vibration frequency of 50Hz and a molding pressure of 15MPa to form a green blank. The green blank, along with the mold, is placed in a constant temperature and humidity curing chamber for low-temperature curing with magnesium-chlorine moisture absorption circulation. The curing temperature is set at 50℃, the relative humidity at 75%, and the curing time at 24 hours. After curing, the blank is demolded and the product is stacked and aged in a naturally ventilated environment for 3 days to obtain the finished port interlocking block.

[0045] Example 2: This embodiment provides a port interlocking block based on synergistic solid waste and its low-temperature preparation process, specifically including the following steps: First, weigh 30.0 parts of Bayer red mud powder and 15.0 parts of carbide slag powder and place them in a forced mixer. Add 31.0 parts of the composite activation liquid obtained in Preparation Example 2 (liquid-to-gel ratio of 0.31). Turn on the mixer and stir at 150 r / min for 4 minutes to pre-activate the slurry by utilizing the exothermic reaction. After the slurry temperature rises, complete the thermo-chemical pre-activation slurry preparation.

[0046] Subsequently, 55.0 parts of blast furnace slag powder were added to the activated slurry, and the mixer speed was increased to 280 r / min and stirred for 2.5 minutes to form a uniform gel slurry. Then, 135.0 parts of pre-mixed aged steel slag coarse aggregate (particle size 4.75mm-9.5mm) and 165.0 parts of aged steel slag fine aggregate (particle size 0mm-4.75mm) were added (the mortar-to-aggregate ratio was 1:3.0), and the mixture was stirred at high speed for another 2.5 minutes to ensure that the slurry fully coated the surface of the aggregate, resulting in a uniformly mixed molding material.

[0047] The molding material is injected into the interlocking block mold and vibrated and pressed for 8 seconds at a vibration frequency of 55Hz and a molding pressure of 18MPa to form a green blank. The green blank, along with the mold, is placed in a constant temperature and humidity curing chamber for low-temperature curing with magnesium-chlorine moisture absorption circulation. The curing temperature is set at 55℃, the relative humidity at 80%, and the curing time at 18 hours. After curing, the blank is demolded and the product is stacked and aged in a naturally ventilated environment for 5 days to obtain the finished port interlocking block.

[0048] Example 3: This embodiment provides a port interlocking block based on synergistic solid waste and its low-temperature preparation process, specifically including the following steps: First, weigh 35.0 parts of Bayer process red mud powder and 20.0 parts of calcium carbide slag powder and place them in a forced mixer. Add 34.0 parts of the composite activating liquid obtained in Preparation Example 3 (liquid-to-gel ratio of 0.34). Turn on the mixer and stir at 180 r / min for 3 minutes. During this period, the heat of reaction released by solid-liquid contact is used for pre-activation. After the slurry temperature rises significantly, the thermo-chemical pre-activation slurry preparation is completed.

[0049] Subsequently, 45.0 parts of blast furnace slag powder were added to the activated slurry, and the mixer speed was increased to 300 r / min and stirred for 2 minutes to form a uniform gel slurry. Then, 175.0 parts of pre-mixed aged steel slag coarse aggregate (particle size 4.75mm-9.5mm) and 175.0 parts of aged steel slag fine aggregate (particle size 0mm-4.75mm) (mortar-to-aggregate ratio of 1:3.5) were added, and the mixture was stirred at high speed for 2 minutes to fully coat the surface of the aggregate and obtain a uniformly mixed molding material.

[0050] The molding material is injected into the interlocking block mold and vibrated and pressed for 5 seconds at a vibration frequency of 60Hz and a molding pressure of 20MPa to form a green blank. The green blank, along with the mold, is placed in a constant temperature and humidity curing chamber for low-temperature curing with magnesium-chlorine moisture absorption circulation. The curing temperature is set at 60℃, the relative humidity at 85%, and the curing time at 12 hours. After curing, the blank is demolded and the product is stacked and aged in a naturally ventilated environment for 7 days to obtain the finished port interlocking block.

[0051] Comparative Examples 1-5: Comparative Example 1: Compared with Example 2, the differences are as follows: all solid cementitious materials (red mud powder, carbide slag powder, and blast furnace slag powder) are replaced with an equal mass of P.O42.5 ordinary Portland cement; the composite activating liquid is replaced with an equal mass of water; and the curing method in step 4 is adjusted to standard curing (temperature 20±2℃, relative humidity ≥95%). The remaining aggregate proportions and molding processes are the same.

[0052] Comparative Example 2: Compared to Example 2, the difference lies in that the composite activating solution obtained in Preparation Example 2 is replaced with an equal proportion of a conventional alkaline activator, which is prepared from water glass, sodium hydroxide, and water, with its modulus adjusted to 1.5 and its solid content mass fraction to 0.25 (consistent with the total salinity of Preparation Example 2). All other aspects are the same.

[0053] Comparative Example 3: Compared to Example 2, the difference lies in that magnesium chloride was not added during the preparation of the composite activating solution. Instead, the amount of calcium chloride was adjusted to maintain the total salinity mass fraction of the solution at 0.25 (i.e., a single calcium chloride solution was used as the activating solution). All other aspects are the same.

[0054] Comparative Example 4: The difference from Example 2 is that the relative humidity during the curing process is adjusted to 100% (saturated humidity) to block the magnesium-chlorine moisture absorption cycle mechanism driven by the unsaturated humidity difference. Everything else is the same.

[0055] Comparative Example 5: Compared to Example 2, the difference lies in that Bayer process red mud powder was not added; instead, it was replaced with equal parts of blast furnace slag powder (i.e., the cementing material consisted of 15.0 parts of calcium carbide slag powder and 85.0 parts of blast furnace slag powder) to investigate the synergistic effect of red mud in a multi-component solid waste system. All other aspects remained the same.

[0056] Test Example 1-2: Test Example 1: Mechanical Properties and Volumetric Stability Test Test method: This test case mainly examines the early strength development of specimens prepared under different formulation systems and process conditions in a low-temperature environment, as well as their volume stability over a long period of time.

[0057] The compressive strength test was conducted in accordance with the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" GB / T50081-2019.

[0058] Take 3 green specimens from the same batch prepared in Examples 1-3 and Comparative Examples 1-5.

[0059] 1-day compressive strength: The compressive strength test was conducted immediately after the low-temperature curing process specified in each embodiment and comparative example was completed and the mold was removed. The loading rate was set to 0.6 MPa / s.

[0060] 28-day compressive strength: After demolding, the specimens were transferred to a standard curing room (temperature 20±2℃, relative humidity ≥95%) for continued curing until 28 days of age. After removing the specimens and wiping off the surface moisture, the test was conducted. The loading rate was set to 0.6 MPa / s.

[0061] The drying shrinkage rate test was conducted in accordance with the "Standard for Test Methods of Basic Performance of Building Mortar" JGJ / T70-2009.

[0062] When preparing the interlocking block specimens for the examples and comparative examples, prism specimens with dimensions of 40mm×40mm×160mm were simultaneously molded, with 3 specimens per group. After molding, the specimens underwent the same low-temperature curing process as the corresponding groups.

[0063] Testing procedure: Immediately after demolding following curing, measure the initial length of the specimen. The specimens were then placed in a constant temperature and humidity length measuring chamber (temperature 20±2℃, relative humidity 60±5%). The length of the specimens was measured at 28 days of age. .

[0064] Calculation: Calculate the rate of change of length, the formula is as follows The average value is taken as the drying shrinkage rate data.

[0065] Test results: The test data of mechanical properties and drying shrinkage rate of specimens in each group are shown in Table 1.

[0066] Table 1. Summary of test data on compressive strength and drying shrinkage of specimens ; Results Analysis and Conclusions: Based on the data in Table 1 and the reaction mechanism analysis, the following is an analysis: Verification of the early strength mechanism at low temperatures: Examples 1-3, under low-temperature conditions of 50℃-60℃, all achieved a 1-day compressive strength of over 30 MPa, with Example 3 reaching 41.5 MPa. In contrast, Comparative Example 1 (ordinary Portland cement) only achieved 11.8 MPa, indicating that the hydration kinetics of traditional cement are severely hindered at low temperatures. Comparative Example 4 (cured under saturated humidity, 22.1 MPa) showed significantly higher strength in the example group, demonstrating that the humidity difference within the matrix caused by the unsaturated humidity environment drove rapid moisture migration, accelerated ion enrichment and precipitation, and promoted the rapid formation of the cementitious structure.

[0067] Verification of volume stability and crack resistance mechanism: Comparative Example 2 (traditional alkali-activated system) exhibited a high drying shrinkage rate of 0.091%, demonstrating typical high shrinkage characteristics of alkali-activated materials. The drying shrinkage rate of the Example Group was controlled between 0.017% and 0.022%, showing a significant reduction.

[0068] Comparative Example 3 (without magnesium component, shrinkage rate 0.041%) and Example 2 (with magnesium component, shrinkage rate 0.017%) show that the introduction of magnesium ions into the system generates a magnesium-containing crystalline phase with micro-expansion characteristics, which effectively compensates for the chemical shrinkage and drying shrinkage of the matrix itself.

[0069] Comparing Comparative Example 4 (saturated humidity, shrinkage rate 0.034%) with the Example Group, it is shown that the presence of only magnesium component and the lack of a moisture absorption cycle mechanism induced by unsaturated humidity cannot fully stimulate the in-situ growth and pore filling effect of magnesium-based products, resulting in lower volume stability than the Example Group.

[0070] Component synergistic effect: The 1-day and 28-day strengths of Comparative Example 5 (without red mud) were lower than those of Example 2, and the shrinkage rate was slightly increased. This indicates that the active aluminum component in the red mud participated in the polymerization reaction and synergistically generated a denser gel product with calcium and magnesium ions, which made a positive contribution to improving the matrix strength and inhibiting shrinkage.

[0071] In summary, the formulation and process shown in the examples, through the synergistic effect of magnesium and calcium ions and the regulation of the unsaturated humidity field, achieved rapid strength establishment in a low-temperature environment and significantly suppressed the shrinkage and deformation of the cementitious material.

[0072] Test Example 2: Durability (Resistance to Seawater Erosion) Test Test method: This test case focuses on evaluating the chloride ion penetration resistance and water resistance of the specimens, taking into account the characteristics of port interlocking blocks being exposed to marine chloride ion erosion and alternating wet and dry environments over a long period of time.

[0073] The chloride ion penetration resistance (RCM method) was determined according to the unsteady-state chloride ion migration method (RCM method) in the "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete" GB / T50082-2009.

[0074] Specimen preparation: The specimens of Examples 1-3 and Comparative Examples 1-5, after being cured to 28 days, were processed into cylindrical specimens with a diameter of 100 mm and a height of 50 mm.

[0075] Test procedure: The sample was saturated with water using a vacuum saturation device. The sample was installed in a rubber sleeve. The cathode solution was 10% NaCl solution, and the anode solution was 0.3 mol / L NaOH solution. A 30V DC voltage was applied and maintained for 24 hours.

[0076] Data Acquisition: After the experiment, the sample was split along the axial direction, and a 0.1 mol / L AgNO3 solution was sprayed onto the cross-section. The chloride ion colorimetric penetration depth was measured, and the unsteady-state chloride ion migration coefficient was calculated based on the experimental temperature, voltage, and time. ).

[0077] The water resistance (softening coefficient) test was conducted in accordance with the relevant provisions of GB / T28635-2012 "Concrete Pavement Bricks".

[0078] Take 6 specimens from each group, aged 28 days.

[0079] Group treatment: Three specimens were immersed in water at (20±5)℃ for 48 hours, removed, dried, and their saturated surface-dry compressive strength was measured. The other three specimens were dried to constant weight in a forced-air drying oven, and their oven-dry compressive strength was determined. ).

[0080] Calculation: Calculate the softening coefficient .

[0081] Test results: The durability test data for each group of specimens are shown in Table 2.

[0082] Table 2. Summary of test data on chloride ion migration coefficient and softening coefficient of specimens ; Results Analysis and Conclusions: Based on the data in Table 2 and the analysis of the microstructure evolution mechanism, the following is an analysis: Verification of the anti-chloride ion penetration mechanism: The chloride ion migration coefficient in the example group remained between 1.5 and 1.8 × 10⁻⁶. The extremely low level is significantly better than that of Comparative Example 1 (conventional silicate cement, 8.4×). ).

[0083] The reason for this is that the present invention introduces a high concentration of chloride ions through a high-salinity activating solution, which react with the aluminum phase in the solid waste during the initial hydration of the cementitious material to generate a chemically stable Friedel salt (3CaO·Al2O3·CaCl2·10H2O). This pre-generated Friedel salt fills the micropores and balances the chloride ion binding capacity within the system, thereby effectively inhibiting the further diffusion and migration of chloride ions in the external environment.

[0084] Comparative Example 3 (without magnesium component, 4.2×) The lower diffusion coefficients in the example group confirm that magnesium-based hydration products (such as magnesium oxychloride phase) further refine the pore structure, forming a denser defensive barrier.

[0085] Water resistance and structural integrity analysis: The softening coefficient of Comparative Example 2 (traditional alkali activation) was only 0.79, indicating that there were many microcracks inside caused by shrinkage, which made it easy for water to penetrate and for strength to decrease during water immersion.

[0086] The softening coefficients of all example groups were above 0.93, with Example 2 reaching 0.97, demonstrating excellent water resistance. This is attributed to the volume compensation effect induced by unsaturated humidity curing, which eliminated microcrack defects. Simultaneously, the calcium-magnesium-aluminum composite cementitious products formed in the system exhibit extremely low solubility in the aqueous environment, ensuring structural strength stability under long-term immersion conditions.

[0087] The impact of process conditions on durability: The chloride ion migration coefficient of Comparative Example 4 (saturated humidity curing) (2.1× The concentration was slightly higher than that of the example group. This indicates that the lack of a "hygroscopic cycle" process driven by an unsaturated moisture difference resulted in a decrease in the penetration and compaction of the cementitious paste into the aggregate interface, leading to a slight weakening of its impermeability.

[0088] In summary, the port interlocking block prepared by this invention achieves excellent resistance to seawater erosion and water stability through the pore-filling effect of Friedel salt, the densification effect of magnesium-based products, and the crack-free microstructure.

Claims

1. A port interlocking block based on collaborative solid waste, characterized in that, Made from the following ingredients in parts by weight: Bayer red mud powder 25-35 parts; 10-20 parts of calcium carbide slag powder; 45-65 parts of blast furnace slag powder; 28-34 parts of composite activating solution; 100-175 parts of aged steel slag coarse aggregate; 150-175 parts of aged steel slag fine aggregate.

2. The port interlocking block based on collaborative solid waste according to claim 1, characterized in that, The composite activating solution is a mixed aqueous solution of calcium chloride and magnesium chloride; based on a total weight of 100 parts of the composite activating solution, the total weight of calcium chloride and magnesium chloride is 22.0-28.0 parts; and the molar ratio of magnesium ions to calcium ions in the solution is 0.15-0.

35.

3. A port interlocking block based on collaborative solid waste as described in claim 1, characterized in that, The particle size of the aged steel slag coarse aggregate is 4.75mm-9.5mm, the particle size of the aged steel slag fine aggregate is 0mm-4.75mm, and when preparing the interlocking block, the mass ratio of the total amount of cementitious material to the total amount of aggregate is controlled between 1:2.5 and 1:3.

5.

4. A port interlocking block based on collaborative solid waste as described in claim 1, characterized in that, The Bayer red mud powder, carbide slag powder, and blast furnace slag powder together constitute a cementing system. The cementing system is activated by the composite activating liquid and reacts with the aluminum phase in the solid waste to generate Friedel salt (3CaO·Al2O3·CaCl2·10H2O) and magnesium-based hydration products to fill the pores.

5. A low-temperature preparation process for port interlocking blocks based on synergistic solid waste, characterized in that, The method for preparing a port interlocking block based on collaborative solid waste as described in any one of claims 1-4 includes the following steps: S1. Thermo-chemical pre-activation pulping: Bayer red mud powder and carbide slag powder are placed in a mixer, and a composite activating liquid is added and stirred. The reaction heat released by solid-liquid contact is used to increase the temperature of the pulp and complete the pre-activation of the cementitious components to obtain activated pulp. S2. Preparation of gelling slurry: Add blast furnace slag powder to the activated slurry obtained in step S1, increase the stirring speed for secondary stirring, and form a uniform gelling slurry. S3. Preparation of molding material: The aged steel slag coarse aggregate and aged steel slag fine aggregate are premixed evenly, and then added to the uniform gel slurry obtained in step S2. Stirring is maintained until the slurry fully coats the surface of the aggregate to obtain molding material. S4. Vibration molding: The molding material is injected into the interlocking block mold and a green blank is formed under the combined action of vibration and pressure. S5. Low-temperature curing: The green body and mold are placed in a constant temperature and humidity environment for magnesium-chlorine moisture absorption cycle curing. The humidity difference caused by the unsaturated humidity environment drives the migration of moisture and the enrichment and precipitation of ions, promoting early strength establishment. S6. Demolding and Aging: After the curing in step S5 is completed, demold the product and place it in a naturally ventilated environment for aging to obtain the finished product.

6. The low-temperature preparation process of a port interlocking block based on synergistic solid waste according to claim 1, characterized in that, In step S1, the stirring speed is controlled at 120-180 r / min, the stirring time is 3-5 minutes, and the slurry temperature is controlled to rise naturally by at least 5°C from room temperature to complete the pre-activation.

7. The low-temperature preparation process of a port interlocking block based on synergistic solid waste according to claim 1, characterized in that, In step S2, the stirring speed is increased to 250-300 r / min, and the stirring time is 2-3 minutes; in step S3, the stirring speed is maintained at the same as in S2 and stirring is continued for 2-3 minutes.

8. The low-temperature preparation process of a port interlocking block based on synergistic solid waste according to claim 1, characterized in that, In step S4, the vibration frequency is 50-60Hz, the molding pressure is 15-20MPa, and the vibration pressing time is 5-10 seconds.

9. The low-temperature preparation process of a port interlocking block based on synergistic solid waste according to claim 1, characterized in that, In step S5, the temperature for low-temperature curing is set to 50-60℃, the relative humidity is set to 75%-85%, and the curing time is 12-24 hours.

10. The low-temperature preparation process of a port interlocking block based on synergistic solid waste according to claim 1, characterized in that, In step S6, the storage and aging time is 3-7 days.