A heat triggered on-demand solidification sulphate based cementitious material and a method of making the same

Abstract

The application discloses a kind of heat trigger on-demand solidification sulphate-based cementitious material and its preparation method and application, belong to building material technical field.The material includes sulphate-based cementitious material, reducing sulfur component, oxidizing agent and specially-made catalyst capsule.Capsule is made of phase change shell material and covers transition metal catalyst, and each component is mixed according to specific steps during preparation, and the melting point of its shell material is 50-80 ℃.The sulphate-based cementitious material can maintain a flowing state for a long time at room temperature;When solidification is needed, the capsule shell material is melted to release the catalyst by external heating, and the reducing sulfur component and the oxidizing agent are catalyzed to produce oxidation-reduction reaction, and in-situ rapid generation of sulphate coagulant, so that the slurry is rapidly coagulated and hardened within a few minutes.The application realizes the active and accurate control of setting time, solves the contradiction between construction and forming stage and the requirement of material rheological property, and is especially suitable for building 3D printing, rapid construction repair and other scenes.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a heat-triggered, on-demand curing sulfate-based cementitious material and its preparation method. Background Technology

[0002] Concrete, as a primary material for modern construction and infrastructure, is widely used in building construction, roads and bridges, tunnels, ports, and various industrial facilities. Its excellent mechanical properties, economy, and applicability make it one of the most widely used building materials globally. With the increasing demands for project cycles and construction efficiency in building construction, the traditional concrete setting process often fails to meet the needs of different construction stages. Setting times that are too short or too long can affect construction progress and quality, making flexible adjustment of setting time particularly important.

[0003] Existing quick-setting materials typically utilize the addition of accelerators to accelerate setting speed for projects requiring rapid hardening. However, the setting process of quick-setting materials is difficult to control; once mixing is complete, the setting rate begins to change rapidly. This "trigger-and-go" characteristic significantly compresses the material's workable time. In time-consuming construction processes such as long-distance pumping and complex casting, the material's fluidity is rapidly lost, easily leading to pipe blockage or molding defects. Furthermore, traditional setting control strategies heavily rely on preset fixed proportions, failing to address dynamic demands during construction. Existing solutions often employ cumbersome two-component online mixing systems, placing extremely stringent requirements on equipment metering accuracy and mixer design, making high-reliability, large-scale application difficult.

[0004] To resolve the conflict between long-term flowability and rapid curing, on-demand curing technology offers a novel single-component solution. This technology aims to provide a cementitious material whose setting time can be flexibly adjusted according to construction requirements, showing great potential in applications such as rapid construction, road repair, and 3D printing. By introducing materials that can trigger a setting reaction under external stimuli, it is possible to achieve precise control of setting time while maintaining good workability, thus adapting to the differentiated rheological requirements of various construction scenarios. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a heat-triggered, on-demand curing sulfate-based gelling material and its preparation method, so as to solve the problem that the setting time of existing gelling materials cannot be actively controlled and cannot meet the construction requirements of "high flow dynamics during construction and rapid curing during molding".

[0006] The technical solution of this invention is implemented as follows: In a first aspect, the present invention provides a heat-triggered, on-demand curing sulfate-based gelling material, the raw materials of which include: gelling material, reducing sulfur component, oxidant and catalyst capsule; wherein, the catalyst capsule includes a phase change shell material and a catalyst core material encapsulated within the phase change shell material, and the phase change shell material of the catalyst capsule has a melting point of 50~80℃.

[0007] Based on the above technical solutions, preferably, the cementitious material, by weight, includes 50-80 parts of β-type hemihydrate gypsum powder, 15-40 parts of granulated blast furnace slag powder, and 0-10 parts of steel slag powder.

[0008] More preferably, the β-type hemihydrate gypsum powder is one or more of calcined phosphogypsum or desulfurized gypsum.

[0009] More preferably, the specific surface area of ​​the granulated blast furnace slag powder is 600~1000 m². 2 / kg.

[0010] More preferably, the reducing sulfur component includes one or more of calcium sulfite, sodium sulfite, sodium bisulfite, sodium dithionite, and sodium thiosulfate.

[0011] More preferably, the oxidant includes one or more of sodium perborate, sodium percarbonate, and sodium persulfate. The reducing sulfur component and the oxidant are stable at room temperature and have little impact on the early setting rate of the cementitious material; under heating or catalytic action, the reducing sulfur component and the oxidant will undergo a redox reaction to generate sulfate, accelerating the setting and hardening of the system.

[0012] More preferably, by weight, the reducing sulfur component is 0.01 to 3 parts; the oxidant is 0.01 to 3 parts.

[0013] More preferably, the catalyst capsule is used in an amount of 0.01 to 2 parts by weight.

[0014] More preferably, the catalyst core material of the catalyst capsule includes one or more of ferrous chloride, ferrous sulfate, copper sulfate, and cobalt sulfate; the phase change shell material includes one or more of paraffin powder, n-octadecyl alcohol powder, stearic acid powder, and lauric acid powder. The catalyst capsule can inhibit premature catalyst participation in the reaction. Upon thermal triggering, the capsule decomposes and releases the catalyst, allowing the reducing sulfur component and oxidant to react rapidly under the dual activation of heating and transition metal catalysis. This generates a large amount of sulfate in situ within the system, accelerating the coagulation and hardening of the cementitious material, thereby achieving on-demand curing.

[0015] More preferably, the preparation method of the catalyst capsule includes: vibrating and mixing the catalyst core material and the phase change shell material at 20-30°C, then heating to 65-80°C and maintaining vibration at this temperature for 5-60 minutes, causing the phase change shell material to melt and coat the surface of the catalyst core material. During continuous vibration, some of the coated particles may temporarily agglomerate, promoting the continuity and densification of the shell material on the core material surface. Finally, heating is stopped and vibration is maintained for 10-30 minutes, allowing the phase change shell material to gradually cool and solidify to form a solid coating layer. Simultaneously, the agglomerates are depolymerized and dispersed under the vibration shearing action, resulting in independent catalyst capsules.

[0016] More preferably, the mass of the phase change shell material is 10% to 200% of the mass of the catalyst core material.

[0017] More preferably, the particle size of the catalyst core material is 14 mesh to 40 mesh, and the particle size range of the phase change shell material is 200 mesh to 400 mesh.

[0018] More preferably, the raw materials further include 0.001-0.5 parts by weight of a retarder and 25-60 parts by weight of water. The retarder is used to control the setting time of the sulfate-based cementitious material to a suitable range. The retarder includes one or more of citric acid retarders, sodium polyphosphate retarders, and protein retarders.

[0019] In a second aspect, the present invention provides a method for preparing the sulfate-based cementitious material described in the first aspect, comprising the following steps: S1. Dry mix the gelling material with the catalyst capsule to obtain a dry mixture; S2. Dissolve the reducing sulfur component, oxidant and retarder in water respectively, then mix them to prepare a mixed solution; S3. Mix the mixed solution obtained in step S2 with the dry mixture obtained in step S1 to obtain the sulfate-based cementitious material slurry.

[0020] Thirdly, the present invention provides the application of the sulfate-based cementitious material described in the first aspect in 3D printing of buildings, rapid road repair or rapid casting projects.

[0021] Fourthly, the present invention provides a method for using the sulfate-based cementitious material described in the first aspect, comprising the following steps: externally heating the cementitious material slurry to raise its temperature to 60~80°C, thereby melting the shell material of the catalyst capsule and releasing the catalyst core material, thereby accelerating the solidification of the cementitious material; the external heating is achieved by a heating device disposed on the conveying path of the cementitious material slurry.

[0022] Based on the above technical solutions, preferably, under the action of a catalyst, the redox reaction between the reducing sulfur component and the oxidant is accelerated, thereby generating a large amount of sulfate to promote coagulation and accelerate the solidification of the cementitious material.

[0023] In a further preferred embodiment, the obtained cementitious material slurry is pumped and cast or 3D printed, and externally heated near its pumping port or extrusion head by an external ceramic heater or resistance heater.

[0024] When the cementitious material is subjected to external heat stimulation during construction, the coating structure of the catalyst capsule softens and ruptures, causing the internal transition metal catalysts such as Fe(II) and Cu(II) to be gradually released into the pore solution. These transition metal ions can significantly activate the oxidant; this process can be understood as a Fenton-like reaction: under the combined action of heat stimulation and metal ions, the oxidant is activated and generates highly oxidizing reactive species such as sulfate radicals, thereby significantly increasing the reaction rate of the system. For example, persulfate (S₂O₈) 2- Taking S2O8 and Fe(II) as examples, 2- It is activated by Fe(II) to generate sulfate radicals (SO4). •- Strongly oxidizing reactive species such as Fe(II) can oxidize low-valence metal ions (e.g., Fe(III)) to high-valence ions (e.g., Fe(III)). A representative reaction can be represented as follows:

[0025]

[0026] The generated SO4 •- It can rapidly oxidize the reducing sulfur components (in the form of sulfite SO3) in the system. 2- For example, it causes the sulfate (SO4) to be converted into sulfate (SO4) 2- This transformation, accompanied by the formation of sulfur-oxygen free radical intermediates (such as SO3), is a process that involves the conversion of these intermediates. •- / SO5 •- (etc.), a representative response can be expressed as:

[0027]

[0028]

[0029] Meanwhile, high-valence metal ions can be reduced back to low-valence states by reducing sulfur components or their free radical intermediates, forming cyclical regeneration catalytic systems such as Fe(II) / Fe(III) and Cu(II) / Cu(III), allowing the activation-conversion process to continue under thermal stimulation. A representative reaction can be represented as follows:

[0030] The aforementioned Fenton-like activation and regeneration mechanism significantly improves the reaction rate between oxidizing and reducing sulfur components, enabling the in-situ and rapid formation of coagulation-promoting sulfate species in the pore solution. This promotes the nucleation and growth of crystals such as gypsum dihydrate and accelerates structural construction, thus speeding up the coagulation and hardening process of cementitious materials. Ultimately, it enables the cementitious materials to rapidly transform from a fluid state during the construction stage to a solid state during the molding stage.

[0031] The present invention has the following advantages over the prior art: (1) The most core beneficial effect of this invention is to achieve intelligent on-demand control of the condensation behavior. Traditional technology adjusts the condensation rate through chemical additives, and the process is preset and irreversible. This invention introduces reducing sulfur components, oxidizing components and catalyst capsules into sulfate-based cementitious materials. Under external thermal stimulation, the reducing sulfur components and oxidizing agents undergo a rapid redox reaction under the action of a catalyst to generate sulfates with condensation-promoting effects, thereby significantly accelerating the condensation and hardening process of the cementitious materials and realizing an active and rapid switch from fluid dynamics to solid state.

[0032] (2) By embedding the catalyst in the present invention, it is difficult for it to fully contact other functional components in the system during the mixing and construction stages at room temperature, thereby reducing the early reaction rate between the reducing sulfur component and the oxidant and significantly improving the stability and operability of the cementitious material under room temperature conditions. Under heating conditions, the coating structure undergoes physical changes, the functional components are rapidly released and react synergistically under the action of the catalyst, so that the redox reaction is rapidly promoted, ensuring that the curing process can be triggered in a timely and effective manner, and realizing the rapid switching of the coagulation behavior from the "latent state" to the "activated state".

[0033] (3) The process of this invention is simple and its application prospects are clear. The material adopts a single mixing system, which does not require complex two-component conveying or mixing equipment. Curing can be triggered simply by applying a heat source to the pump port or the print head, which greatly simplifies the construction process. This characteristic makes it very suitable for advanced construction scenarios with precise requirements for setting time, such as rapid road repair or rapid casting projects in 3D printing of buildings. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 The catalyst capsule prepared for this invention: wherein Figure 1 (a) represents uncoated ferrous sulfate particles. Figure 1 (b) is the catalyst capsule from Example 1. Figure 1 (c) is the catalyst capsule in Example 2. 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 a part of the embodiments of the present invention, and not all of the 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 catalyst capsules prepared in this invention are as follows: Figure 1 As shown, where Figure 1 (a) is the ferrous sulfate core material used in Examples 1 and 2, which is a light green irregular block with a particle size of about 1 mm. Figure 1 (b) and (c) are the catalyst capsules used in Examples 1 and 2, respectively. White paraffin powder is melt-coated on the surface of ferrous sulfate, which effectively inhibits the release of the core material in the slurry.

[0038] Table 1: Material Source Description Table

[0039] One part = 1 g.

[0040] Example 1: A heat-triggered, on-demand curing sulfate-based cementitious material, by weight, comprises the following raw material components and contents: 67 parts of β-type hemihydrate gypsum powder; 25 parts of granulated blast furnace slag powder; 8 parts of steel slag powder; 1 part of reducing sulfur component; 2 parts of oxidant; 0.5 parts of catalyst capsule; 0.01 parts of retarder; and 45 parts of water; wherein the β-type hemihydrate gypsum powder is calcined phosphogypsum, the reducing sulfur component is sodium sulfite, the oxidant is sodium persulfate, and the retarder is a protein-based retarder.

[0041] The catalyst capsules are prepared as follows: 100 g of ferrous sulfate (core material) with a particle size of 20 mesh and 40 g of paraffin powder (shell material) with a particle size of 200 mesh are added to a vibrating device at a core-to-shell material mass ratio of 100:40. The mixture is vibrated and mixed at 25°C to form a dry mixture. Vibration is then maintained while the material is heated to 75°C. Vibration continues at this temperature for 10 minutes, causing the paraffin to melt and coat the surface of the ferrous sulfate particles under vibration. After heating is stopped, vibration continues for another 10 minutes to allow the shell material to cool and solidify. Simultaneously, the particles are dispersed under the shearing action of vibration, ultimately yielding independent catalyst capsules with a monomeric structure.

[0042] The preparation and curing method of the heat-triggered, on-demand curing sulfate-based cementitious material are as follows: S1. Place β-type hemihydrate gypsum powder, granulated blast furnace slag powder, steel slag powder and the above catalyst capsules in a planetary mixer and dry mix for 3 minutes to obtain a dry mixture.

[0043] S2. Dissolve the retarder, sodium sulfite and sodium persulfate in water respectively, and then mix them evenly with a magnetic stirrer to obtain solution A.

[0044] S3. Add solution A to the dry mix and mix for 2 minutes using a planetary mixer to obtain a workable cementitious material slurry.

[0045] S4. When rapid curing is required, the slurry is heated to 60°C using a resistance heater, melting the paraffin shell of the catalyst capsule and releasing the ferrous sulfate catalyst. The catalyst accelerates the redox reaction between sodium sulfite and sodium persulfate, rapidly generating sulfate coagulants, thereby driving the slurry to solidify and harden quickly.

[0046] Example 2: A heat-triggered, on-demand curing sulfate-based cementitious material, by weight, comprises the following raw material components and contents: 60 parts of β-type hemihydrate gypsum powder; 40 parts of granulated blast furnace slag powder; 0 parts of steel slag powder; 1 part of reducing sulfur component; 2 parts of oxidant; 0.8 parts of catalyst capsule; 0.01 parts of retarder; and 45 parts of water; wherein the β-type hemihydrate gypsum powder is desulfurized gypsum, the reducing sulfur component is sodium sulfite, the oxidant is sodium perborate, and the retarder is a protein-based retarder.

[0047] The catalyst capsules are prepared as follows: 100 g of ferrous chloride (core material) with a particle size of 14 mesh and 60 g of paraffin powder (shell material) with a particle size of 200 mesh are added to a vibrating device at a core-to-shell material mass ratio of 100:60. The mixture is vibrated and mixed at 20°C to form a dry mixture. Vibration is then maintained while the material is heated to 65°C. Vibration continues at this temperature for 5 minutes, causing the paraffin to melt and coat the surface of the ferrous chloride particles under vibration. After heating is stopped, vibration continues for 10 minutes to allow the shell material to cool and solidify. Simultaneously, the particles are dispersed under the shearing action of vibration, ultimately yielding independent catalyst capsules with a monomeric structure.

[0048] The preparation and curing-triggered curing method of this sulfate-based cementitious material are as follows: S1. Place β-type hemihydrate gypsum powder, granulated blast furnace slag powder, steel slag powder and the above catalyst capsules in a planetary mixer and dry mix for 3 minutes to obtain a dry mixture.

[0049] S2. Dissolve the retarder, sodium sulfite and sodium persulfate in water respectively, and then mix them evenly with a magnetic stirrer to obtain solution A.

[0050] S3. Add solution A to the dry mix and mix for 2 minutes using a planetary mixer to obtain a workable cementitious material slurry.

[0051] S4. When rapid curing is required, the slurry is heated to 60°C using a resistance heater, melting the paraffin shell of the catalyst capsule and releasing the ferrous chloride catalyst. The catalyst accelerates the redox reaction between sodium sulfite and sodium persulfate, rapidly generating sulfate coagulants, thereby driving the slurry to solidify and harden quickly.

[0052] Example 3: A heat-triggered, on-demand curing sulfate-based cementitious material, by weight, comprises the following raw material components and contents: 70 parts β-type hemihydrate gypsum powder; 20 parts granulated blast furnace slag powder; 10 parts steel slag powder; 3 parts reducing sulfur component; 3 parts oxidant; 0.5 parts catalyst capsule; 0.05 parts retarder; and 60 parts water; wherein the β-type hemihydrate gypsum powder is calcined phosphogypsum, the reducing sulfur component is sodium thiosulfate, the oxidant is sodium persulfate, and the retarder is a citric acid retarder.

[0053] The catalyst capsules are prepared as follows: 100 g of ferrous sulfate (core material) with a particle size of 40 mesh and 100 g of n-octadecanoic acid powder (shell material) with a particle size of 400 mesh are added to a vibrating device at a core-to-shell material mass ratio of 100:100. The mixture is vibrated and mixed at 30°C to form a dry mixture. Vibration is then maintained while the material is heated to 80°C. Vibration continues at this temperature for 60 minutes, causing the n-octadecanoic acid powder to melt and coat the ferrous sulfate particles under vibration. After heating is stopped, vibration continues for 30 minutes to allow the shell material to cool and solidify. Simultaneously, the particles are dispersed under the shearing action of vibration, ultimately yielding independent catalyst capsules with a monomeric structure.

[0054] The preparation and curing-triggered curing method of this sulfate-based cementitious material are as follows: S1. Place β-type hemihydrate gypsum powder, granulated blast furnace slag powder, steel slag powder and the above catalyst capsules in a planetary mixer and dry mix for 3 minutes to obtain a dry mixture.

[0055] S2. Dissolve the retarder, sodium sulfite and sodium persulfate in water respectively, and then mix them evenly with a magnetic stirrer to obtain solution A.

[0056] S3. Add solution A to the dry mix and mix for 2 minutes using a planetary mixer to obtain a workable cementitious material slurry.

[0057] S4. When rapid curing is required, the slurry is heated to 80°C using a resistance heater, melting the n-octadecyl alcohol shell of the catalyst capsule and releasing the ferrous sulfate catalyst. The catalyst accelerates the redox reaction between sodium sulfite and sodium persulfate, rapidly generating sulfate accelerators, thereby driving the slurry to solidify and harden quickly.

[0058] Example 4: A heat-triggered, on-demand curing sulfate-based cementitious material, by weight, comprises the following raw material components and contents: 70 parts β-type hemihydrate gypsum powder; 20 parts granulated blast furnace slag powder; 10 parts steel slag powder; 1 part reducing sulfur component; 1 part oxidant; 0.5 parts catalyst capsule; 0.02 parts retarder; and 45 parts water; wherein the β-type hemihydrate gypsum powder is calcined phosphogypsum, the reducing sulfur component is sodium dithionite, the oxidant is sodium percarbonate, and the retarder is a citric acid retarder.

[0059] The catalyst capsules are prepared as follows: 100 g of copper sulfate (core material) with a particle size range of 14-30 mesh and 10 g of stearic acid powder (shell material) with a particle size range of 200-300 mesh are added to a vibrating device at a core-to-shell material mass ratio of 100:10. The mixture is vibrated and mixed at room temperature to form a dry mixture. Vibration is then maintained while the material is heated to 80°C. Vibration continues at this temperature for 10 minutes to melt the stearic acid and coat the surface of the copper sulfate particles under vibration. After heating is stopped, vibration continues for 20 minutes to allow the shell material to cool and solidify. Simultaneously, the particles are dispersed under the shearing action of vibration, ultimately yielding independent catalyst capsules with a monomeric structure.

[0060] The preparation and curing-triggered curing method of this sulfate-based cementitious material are as follows: S1. Place β-type hemihydrate gypsum powder, granulated blast furnace slag powder, steel slag powder and the above catalyst capsules in a planetary mixer and dry mix for 3 minutes to obtain a dry mixture.

[0061] S2. Dissolve the retarder, sodium dithionite and sodium percarbonate in water respectively, and then mix them evenly with a magnetic stirrer to obtain solution A.

[0062] S3. Add solution A to the dry mix and mix for 2 minutes using a planetary mixer to obtain a workable cementitious material slurry.

[0063] S4. When rapid curing is required, the slurry is heated to 60°C using a resistance heater, melting the stearic acid shell of the catalyst capsule and releasing the copper sulfate catalyst. The catalyst accelerates the redox reaction between sodium dithionite and sodium percarbonate, rapidly generating sulfate accelerators, thereby driving the slurry to solidify and harden quickly.

[0064] Example 5: A heat-triggered, on-demand curing sulfate-based cementitious material, by weight, comprises the following raw material components and contents: 80 parts of β-type hemihydrate gypsum powder; 20 parts of granulated blast furnace slag powder; 0 parts of steel slag powder; 2 parts of reducing sulfur component; 1 part of oxidant; 0.5 parts of catalyst capsule; 0.02 parts of retarder; and 45 parts of water; wherein the β-type hemihydrate gypsum powder is calcined phosphogypsum, the reducing sulfur component is sodium sulfite, the oxidant is sodium perborate, and the retarder is sodium polyphosphate retarder.

[0065] The catalyst capsules are prepared as follows: 100 g of copper sulfate (core material) with a particle size range of 20-30 mesh and 200 g of n-octadecanoic acid powder (shell material) with a particle size range of 200-300 mesh are added to a vibrating device at a core-to-shell material mass ratio of 100:200. The mixture is vibrated and mixed at room temperature to form a dry mixture. Vibration is then maintained while the material is heated to 80°C. Vibration continues at this temperature for 10 minutes, causing the n-octadecanoic acid to melt and coat the surface of the copper sulfate particles under vibration. After heating is stopped, vibration continues for 20 minutes to allow the shell material to cool and solidify. Simultaneously, the particles are dispersed under the shearing action of vibration, ultimately yielding independent catalyst capsules with a monomeric structure.

[0066] The preparation and curing-triggered curing method of this sulfate-based cementitious material are as follows: S1. Place β-type hemihydrate gypsum powder, granulated blast furnace slag powder, steel slag powder and the above catalyst capsules in a planetary mixer and dry mix for 3 minutes to obtain a dry mixture.

[0067] S2. Dissolve the retarder, sodium sulfite and sodium perborate in water respectively, and then mix them evenly with a magnetic stirrer to obtain solution A.

[0068] S3. Add solution A to the dry mix and mix for 2 minutes using a planetary mixer to obtain a workable cementitious material slurry.

[0069] S4. When rapid curing is required, the slurry is heated to 80°C using a resistance heater, melting the n-octadecyl alcohol shell of the catalyst capsule and releasing the copper sulfate catalyst. The catalyst accelerates the redox reaction between sodium sulfite and sodium perborate, rapidly generating sulfate accelerators, thereby driving the slurry to solidify and harden quickly.

[0070] Comparative Example 6: The difference between this comparative example and Example 1 above is that this comparative example does not add reducing sulfur components, oxidants, and catalyst capsules, and is a conventional method for preparing sulfate-based cementitious materials. This comparative example is a sulfate-based cementitious material, and by weight, the raw material components and contents are as follows: 67 parts of β-type hemihydrate gypsum powder; 25 parts of granulated blast furnace slag; 8 parts of steel slag; 0.01 parts of retarder; and 45 parts of water.

[0071] This comparative example describes a sulfate-based cementitious material and its preparation method. The preparation method includes the following steps: S1. Place β-type hemihydrate gypsum powder, granulated blast furnace slag powder and steel slag powder in a planetary mixer and mix for 3 minutes to obtain a dry mixture. S2. Before use, add the retarder to water and stir evenly with a magnetic stirrer to obtain solution A; S3. Add solution A to the dry mixture and continue mixing with a planetary mixer for 2 minutes to obtain a sulfate-based cementitious material.

[0072] Comparative Example 7: The difference between this comparative example and Example 1 above is that this comparative example did not involve thermal triggering of the sulfate-based cementitious material. The remaining steps are the same as in Example 1, and will not be repeated here.

[0073] Comparative Example 8: The difference between this comparative example and Example 1 is that the catalyst in this comparative example was not coated; it was directly incorporated into the adhesive. The remaining steps are the same as in Example 1 and will not be repeated here.

[0074] Comparative Example 9: The difference between this comparative example and Example 1 above is that no catalyst capsule or catalyst was added in this comparative example. The remaining steps are the same as in Example 1, and will not be repeated here.

[0075] Comparative Example 10: The difference between this comparative example and Example 1 above is that the cementing material in this comparative example is 0 parts of β-type hemihydrate gypsum powder, 80 parts of granulated blast furnace slag, and 20 parts of steel slag. The remaining steps are the same as in Example 1, and will not be repeated here.

[0076] The setting times of the above embodiments and comparative examples are shown in Table 2: Table 2:

[0077] Table 2 shows that: Comparative Example 6, a conventional sulfate-based cementitious material, had a setting time extended to 254 min under the action of a retarder. When a reducing sulfur component, oxidant, and catalyst capsule were added, the setting time at room temperature remained at 170 min (Comparative Example 7). This is because the reducing sulfur component and oxidant are stable at room temperature, and the sulfites and persulfates within them do not have a promoting effect on the setting of the sulfate-based cementitious material. However, under heating (Example 1), the catalyst capsule ruptures, releasing a transition metal catalyst. Under the dual action of thermal activation and transition metal catalysis, the reducing sulfur component and oxidant undergo a redox reaction, rapidly generating a sulfate accelerator in situ, thereby shortening the slurry setting time to 12 min.

[0078] If the catalyst is not coated and directly added to the adhesive (Comparative Example 8), the catalyst will directly catalyze the reducing sulfur components and oxidant to generate sulfate accelerators after water is added and mixed, causing the slurry to solidify directly within 4 minutes, making it impossible to cast or pump. In Comparative Example 9, no catalyst capsules or catalyst were added; instead, a thermal activation method was used to generate sulfate accelerators. Based on its setting time, it can be seen that the thermal activation method alone can accelerate the setting speed of sulfate-based cementitious materials, but its setting time is still relatively long and cannot meet the requirements of on-demand curing. In Comparative Example 10, β-type hemihydrate gypsum powder was not used. Although the reducing sulfur components and oxidant generated sulfate accelerators after activation, the absence of hemihydrate calcium sulfate prevented the rapid generation of large amounts of ettringite and dihydrate calcium sulfate, resulting in a relatively long setting time.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A heat-triggered, on-demand curing sulfate-based cementitious material, characterized in that, Its raw materials include: cementing materials, reducing sulfur components, oxidants and catalyst capsules; wherein, the catalyst capsule includes a phase change shell material and a catalyst core material encapsulated within the phase change shell material, and the phase change shell material of the catalyst capsule has a melting point of 50~80℃.

2. The sulfate-based cementitious material as described in claim 1, characterized in that, The reducing sulfur component includes one or more of calcium sulfite, sodium sulfite, sodium bisulfite, sodium dithionite, and sodium thiosulfate; the oxidizing agent includes one or more of sodium perborate, sodium percarbonate, and sodium persulfate.

3. The sulfate-based cementitious material as described in claim 1, characterized in that, The reducing sulfur component comprises 0.01 to 3 parts by weight, and the oxidizing agent comprises 0.01 to 3 parts by weight.

4. The sulfate-based cementitious material as described in claim 1, characterized in that, The catalyst capsule is used in an amount of 0.01 to 2 parts by weight.

5. The sulfate-based cementitious material as described in claim 1, characterized in that, The catalyst core material of the catalyst capsule includes one or more of ferrous chloride, ferrous sulfate, copper sulfate, and cobalt sulfate; the phase change shell material includes one or more of paraffin powder, n-octadecyl alcohol powder, stearic acid powder, and lauric acid powder.

6. The sulfate-based cementitious material as described in claim 1, characterized in that, The mass of the phase change shell material is 10% to 200% of the mass of the catalyst core material.

7. The sulfate-based cementitious material as described in claim 1, characterized in that, By weight, its raw materials also include 0.001 to 0.5 parts of retarder and 25 to 60 parts of water.

8. A method for preparing a sulfate-based cementitious material as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Dry mix the gelling material with the catalyst capsule to obtain a dry mixture; S2. Dissolve the reducing sulfur component, oxidant and retarder in water respectively, then mix them to prepare a mixed solution; S3. Mix the mixed solution obtained in step S2 with the dry mixture obtained in step S1 to obtain the sulfate-based cementitious material slurry.

9. The application of the sulfate-based cementitious material as described in any one of claims 1-7 in 3D printing of buildings, rapid road repair or rapid casting projects.

10. A method of using the sulfate-based cementitious material as described in any one of claims 1-7, characterized in that, Includes the following steps: The cementitious material slurry is externally heated to raise its temperature to 60-80°C, thereby melting the shell of the catalyst capsule and releasing the catalyst core material, which accelerates the solidification and curing of the cementitious material; the external heating is achieved by a heating device installed on the conveying path of the cementitious material slurry.

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