Rapid-hardening cement mortar and use method therefor

Abstract

The present application relates to the technical field of building materials and discloses a rapid-hardening cement mortar and a use method therefor. The quick-hardening cement mortar is composed of the following components: rapid-hardening sulfoaluminate cement, ordinary Portland cement, an aggregate, an admixture, and a fiber composition. The fiber composition comprises galvanized steel fibers and polymer fibers. The polymer fibers include PVA fibers. A film layer modified with a silane coupling agent is formed on the surfaces of the galvanized steel fibers and the polymer fibers. The silane coupling agent is selected from at least one of aminopropyltriethoxysilane and a diamino-functional silane. The present application uses the galvanized steel fibers and polymer fibers in the cement mortar. The polymer fibers utilize the intense hydration heat generated by cement within a short period of time to generate compressive stress in a cement block, and have a synergistic effect with the galvanized steel fibers, thereby providing an overall anti-drying-cracking effect for the cement block. By means of the surface modification scheme using a silane coupling agent, the anti-drying-cracking effect is enhanced, thereby allowing short fibers to achieve the performance of conventional long fibers.

Description

A rapid-hardening cement mortar and its application method Technical Field

[0001] This application relates to the technical field of building materials, and in particular to a fast-setting cement mortar and its application method. Background Technology

[0002] Currently, municipal facilities such as roads and sewage wells frequently require repair of damaged areas. To minimize post-construction closure time and expedite traffic reopening, ultra-early-strength and fast-hardening cement-based repair materials are often used. These materials typically exhibit a compressive strength exceeding 20 MPa after 2-3 hours of water addition, along with a setting time of over 20 minutes and good fluidity for easy pouring and leveling.

[0003] However, due to their combination of rapid hardening and early strength, these materials undergo a violent cement hydration reaction within tens of minutes of application, generating a large amount of heat of hydration. This causes the volume of the finished cement block to expand. After most of the reaction has completed, the total volume of the newly formed dense solid phase is smaller than that of the unhardened cement mortar, causing the cement block to shrink. Simultaneously, as the heat of hydration dissipates and cooling occurs, the volume of the hardened cement block also shrinks. The combined shrinkage effect of these two processes leads to cracking of the hardened cement block, a phenomenon more severe in cement materials with shorter curing times.

[0004] The solution in related technologies is to add auxiliary materials such as fly ash and sand to cement to replace part of the cement powder and reduce the overall heat of hydration. The disadvantage of this solution is that the addition of various powders and aggregates will adversely affect the compressive strength of the cement paste after curing. For cement-based materials that are designed for rapid hardening and early strength, the amount added should not be too much, otherwise the strength after 2 hours will not meet the standard.

[0005] Another common solution is to add a certain amount of expanding agent to the formula to counteract the drying shrinkage effect of cement curing. Common expanding agents include magnesium oxide expanding agent and calcium sulfoaluminate (such as the patent with publication number CN117819921A). However, this type of admixture may have a compounding effect with other complex admixtures, which cannot effectively solve the cracking problem and increases production costs and difficulty. Summary of the Invention

[0006] The purpose of this application is to provide a fast-hardening cement mortar to solve the problem of cement block cracking caused by the expansion followed by solidification shrinkage after the intense heat of cement hydration.

[0007] This invention provides a rapid-hardening cement mortar, which is composed of the following components in parts by weight:

[0008] The mixture comprises 60-90 parts of rapid-hardening sulfoaluminate cement, 10-40 parts of ordinary Portland cement, 80-120 parts of aggregate, 0.5-3 parts of admixture, and 0.5-4 parts of fiber composition; wherein the fiber composition comprises galvanized steel fiber and polymer fiber, and the polymer fiber comprises PVA fiber.

[0009] The galvanized steel fiber and polymer fiber have a film layer modified with a silane coupling agent on their surface, wherein the silane coupling agent is selected from at least one of aminopropyltriethoxysilane and diamino functional group silane.

[0010] Preferably, the surface film layer of the galvanized steel fiber and polymer fiber is a composite film layer modified with aminopropyltriethoxysilane and diamino functional group silane; and / or, the modification process of the galvanized steel fiber and polymer fiber is to first impregnate with diamino functional group silane and then dry, and then impregnate with aminopropyltriethoxysilane and then dry.

[0011] Preferably, the average preload coefficient of the polymer fiber The range is 3000 Pa / ℃ to 6000 Pa / ℃, with an average preload coefficient. The calculation method is as follows: ;in, For the first The mass fractions corresponding to each polymer fiber; For the first The elastic modulus corresponding to each polymer fiber; For the first The coefficient of thermal expansion of each polymer fiber; n is the number of types of polymer fibers; For loop variable, =1, 2, ..., n;

[0012] And / or, the polymer fibers also include at least one of PP fibers, PAN fibers, PET fibers or PA6 fibers.

[0013] Preferably, the length ratio of the galvanized steel fiber to the polymer fiber is (2~4):1; and / or, the fiber length of the galvanized steel fiber is 12mm~18mm, and the length of the polymer fiber is 3mm~8mm; and / or, the length of the galvanized steel fiber is 15mm, and the length of the polymer fiber is 5mm.

[0014] Preferably, the mass ratio of the fiber composition to the total amount of rapid-hardening sulfoaluminate cement and ordinary Portland cement is (2~4):100; and / or, the mass ratio of the galvanized steel fiber to the polymer fiber is (1~3):(0.5~1.5).

[0015] Preferably, the zinc layer thickness in the galvanized steel fiber is 0.2μm~0.6μm.

[0016] Preferably, the rapid-hardening cement mortar is composed of the following components in parts by weight: 70-80 parts rapid-hardening sulfoaluminate cement, 20-30 parts ordinary Portland cement, 90-110 parts aggregate, 1-3 parts galvanized steel fiber, 0.5-2 parts PVA fiber, and 1-2 parts admixture.

[0017] Preferably, the rapid-hardening cement mortar is composed of the following components in parts by weight: 75 parts rapid-hardening sulfoaluminate cement, 25 parts ordinary Portland cement, 100 parts aggregate, 2 parts copper-plated steel fiber, 1 part PVA fiber, and 1.39 parts admixture.

[0018] The present invention also provides a method for applying quick-hardening cement mortar, wherein the quick-hardening cement mortar is weighed according to the mass ratio, and water is added and stirred to mix evenly.

[0019] Preferably, when using 180 to 220 parts by weight of the rapid-hardening cement mortar, the amount of water added during mixing is 20 to 30 parts.

[0020] Compared with the prior art, the beneficial effects of this application are as follows:

[0021] This application utilizes galvanized steel fibers and polymer fibers in cement mortar. The polymer fibers take advantage of the intense hydration heat of cement in a short time to generate compressive stress in the cement block, while working synergistically with the galvanized steel fibers to produce an overall anti-cracking effect for the cement block.

[0022] Secondly, by modifying the surface of the silane coupling agent, its anti-cracking effect is enhanced, allowing it to achieve the effect of ordinary long fibers with short fibers; at the same time, the short fiber method ensures the convenience of the construction and mixing process and the uniform dispersion of the fiber composition in cement mortar.

[0023] Furthermore, by controlling the average preload coefficient of polymer fibers in cement blocks, this invention better utilizes the heat of hydration released by cement to increase the elongation and deformation of polymer fibers, and better utilizes the local stress generated during the cooling process. In addition, by controlling the average preload coefficient of polymer fibers in cement blocks, the amount of polymer fibers used can be greatly reduced. Detailed Implementation

[0024] 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.

[0025] This invention provides a rapid-hardening cement mortar, which is composed of the following components in parts by weight: 60-90 parts of rapid-hardening sulfoaluminate cement, 10-40 parts of ordinary Portland cement, 80-120 parts of aggregate, 0.5-3 parts of admixture, and 0.5-4 parts of fiber composition; the fiber composition includes galvanized steel fibers and polymer fibers, the polymer fibers including PVA fibers; wherein, the galvanized steel fibers and polymer fibers have a film layer modified by a silane coupling agent on their surface, the silane coupling agent being selected from at least one of aminopropyltriethoxysilane and diamino functional group silane.

[0026] First, by uniformly distributing galvanized steel fibers and polymer fibers within the cementitious matrix, once cracks occur, the bonding force between the fibers and the cement block must be overcome for them to continue propagating. Considering the surface characteristics of the galvanized steel fiber layer and the PVA fibers, the fiber combination modified with the aforementioned silane coupling agent further enhances crack resistance, effectively transmitting external mechanical impacts and mitigating localized cracking caused by stress concentration. Second, PVA fibers play a major role in resisting early-stage cement shrinkage cracking. Galvanized steel fibers are expensive and offer little benefit to the compressive strength in the first two hours; however, using galvanized steel fibers simultaneously increases service life and resists vehicle crushing and impacts during use, offering a significantly longer service life than polymer fibers. Furthermore, the use of a galvanized steel fiber coating, rather than other metal coatings (such as copper), better addresses the corrosive environment of wastewater with complex chemical compositions surrounding sewage wells.

[0027] Thus, this application uses galvanized steel fibers and polymer fibers in cement mortar. The polymer fibers utilize the intense heat of hydration of cement in a short time to generate compressive stress in the cement block, while working synergistically with the galvanized steel fibers to produce an overall anti-cracking effect for the cement block.

[0028] This invention does not impose any particular limitations on rapid-hardening sulfoaluminate cement and ordinary Portland cement, and any cement known to those skilled in the art can be used; for example, the compressive strength grade of the rapid-hardening sulfoaluminate cement R.SAC can be 42.5, and the compressive strength grade of the ordinary Portland cement PO can be 52.5.

[0029] In one embodiment of the present invention, the surface film layer of the galvanized steel fiber and the polymer fiber is a composite film layer modified by aminopropyltriethoxysilane and diamino functional group silane; and / or, the modification process of the galvanized steel fiber and the polymer fiber is to first impregnate with diamino functional group silane and then dry, and then impregnate with aminopropyltriethoxysilane and then dry.

[0030] Through research on various silane coupling agent modification schemes, this study investigated the effects of modifying the zinc-plated layer and PVA surface of the fiber composition with aminopropyltriethoxysilane and diamino-functional silane, resulting in cement blocks with superior resistance to cracking. Preliminary analysis suggests that the silane coupling agent modification scheme significantly increases the number of -OH groups attached to the fiber surface. These -OH groups can then form strong hydrogen bonds with the -OH groups in the cement paste, greatly enhancing the bonding strength between the two fibers and the cement paste after curing. Furthermore, this composite surface modification allows for a significant reduction in fiber usage while still meeting design specifications.

[0031] In one embodiment of the present invention, the average preload coefficient of the polymer fiber The range is 3000 Pa / ℃ to 6000 Pa / ℃; and / or, the polymer fiber also includes at least one of PP fiber, PAN fiber, PET fiber or PA6 fiber.

[0032] Average preload coefficient In polymer fiber solutions with a temperature range of 3000 Pa / ℃ to 6000 Pa / ℃, the resulting polymer compounds freely elongate upon heating and are then locked in this elongated state by cement curing. This is highly suitable for ultra-early-strength cement-based materials that generate intense heat of hydration in a short period. Furthermore, the polymer fibers first elongate and extend to a certain extent at high temperatures and are then locked and bonded to the cement block. Subsequently, at low-temperature cooling, the polymer fibers shrink, but the cement block prevents this shrinkage, thus generating a pre-tightening force that ultimately prevents crack initiation or crack propagation.

[0033] During the research and development of polymer fibers to prevent the propagation of bulk cracks, it was found that the key considerations for polymer fiber solutions are their elastic modulus E and coefficient of thermal expansion α. ​​The elastic modulus E of polymer fibers ranges from 9 GPa to 40 GPa, and the coefficient of thermal expansion α ranges from 30 × 10⁻⁶. -6 / ℃~200×10 -6 / ℃. Preliminary hypothesis suggests that the single polymer fiber generates localized compressive stress F on the cement block, and the derivation process of this localized compressive stress F is as follows:

[0034] Where E is the elastic modulus; s is the fiber cross-sectional area; ΔL is the fiber elongation length; L is the original fiber length; α is the coefficient of thermal expansion; and ΔT is the temperature difference.

[0035] For various polymer fiber combination schemes, the average preload coefficient of the polymer fibers is... The calculation method is as follows: ;in, For the first The mass fractions corresponding to each polymer fiber; For the first The elastic modulus corresponding to each polymer fiber; For the first The coefficient of thermal expansion of each polymer fiber; n is the number of types of polymer fibers; For loop variable, =1, 2, ..., n.

[0036] Furthermore, the linear thermal expansion coefficient of cement blocks is 10 × 10⁻⁶. -6 / ℃, when the α value of the polymer fiber used is lower than this value, it will affect its crack resistance.

[0037] In one embodiment of the present invention, the length ratio of galvanized steel fiber to polymer fiber is (2~4):1; and / or, the fiber length of galvanized steel fiber is 12~18mm and the length of polymer fiber is 3~8mm; and / or, the length of galvanized steel fiber is 15mm and the length of polymer fiber is 5mm.

[0038] Firstly, a short fiber scheme was adopted for both galvanized steel fibers and polymer fibers, with maximum lengths of 18mm and 8mm respectively. This was primarily to address the impact of excessively long fibers on the uniform dispersion during actual construction. The length of the galvanized steel fibers could be selected from 12mm, 14mm, 15mm, 16mm, and 18mm. Controlling the fiber length to 15mm simultaneously met the design requirements for uniformity during mixing, as well as the flexural and compressive strength of the cement blocks. Furthermore, while excessively long steel fibers could improve flexural strength to some extent, their effect on improving compressive strength was very limited. The length ratio of galvanized steel fibers to polymer fibers could be 2:1, 3:1, or 4:1. This was mainly because excessively long polymer fibers were prone to entanglement with the galvanized steel fibers, and the resulting agglomeration would affect the deformation of the polymer fibers and their stress transmission effect. Research found that when the length of the galvanized steel fibers was 15mm and the length of the polymer fibers was 5mm, the combination of the two had a significant and superior effect on preventing the propagation of cracks in the cement blocks.

[0039] Meanwhile, by modifying the surface of the silane coupling agent, its anti-cracking effect is enhanced, allowing it to achieve the effect of ordinary long fibers with short fibers; at the same time, the short fiber method ensures the convenience of the construction and mixing process and the uniform dispersion of the fiber composition in cement mortar.

[0040] In one embodiment of the present invention, the mass ratio of the fiber composition to the total amount of rapid-hardening sulfoaluminate cement and ordinary Portland cement is (2~4):100; and / or, the mass ratio of galvanized steel fiber to polymer fiber is (1~3):(0.5~1.5).

[0041] If the mass ratio of the fiber composition to the total amount of rapid-hardening sulfoaluminate cement and ordinary Portland cement is too high, it will affect the compressive strength of the molded cement block. The ratio can be controlled at 2:100, 2.5:100, 3:100, or 3.5:100. Preferably, when the ratio is controlled at 3:100, the bonding force between the fiber and cement can be greatly enhanced to ensure compressive and flexural strength.

[0042] The mass ratio of galvanized steel fiber to polymer fiber can be 1:1, 2:1, 3:1, 1:0.5, or 1:1.5. Preferably, the ratio is controlled at 2:1.

[0043] In one embodiment of the present invention, the zinc layer thickness in the galvanized steel fiber is 0.2~0.6μm. The zinc layer thickness can be selected from 0.2μm, 0.3μm, 0.4μm, 0.5μm, and 0.6μm; the greater the zinc layer thickness, the stronger the corrosion resistance of the steel fiber; however, the zinc layer will lead to a significant increase in cost and affect the compressive strength and flexural strength of the formed cement block. Among them, a zinc layer thickness of 0.5μm can better balance the effects of crack resistance and service life. Calculated at 50 nanometers of corrosion per year, the cement block is expected to be usable for 10 years after its formation.

[0044] In one embodiment of the present invention, the rapid-hardening cement mortar is composed of the following components in parts by weight: 70-80 parts of rapid-hardening sulfoaluminate cement, 20-30 parts of ordinary Portland cement, 90-110 parts of aggregate, 1-3 parts of galvanized steel fiber, 0.5-2 parts of PVA fiber, and 1-2 parts of admixture.

[0045] In one embodiment of the present invention, the rapid-hardening cement mortar is composed of the following components in parts by weight: 75 parts rapid-hardening sulfoaluminate cement, 25 parts ordinary Portland cement, 100 parts aggregate, 2 parts copper-plated steel fiber, 1 part PVA fiber, and 1.39 parts admixture.

[0046] The present invention also provides a method for applying quick-hardening cement mortar, wherein quick-hardening cement mortar is weighed according to the mass ratio, and water is added and stirred to mix evenly.

[0047] In one embodiment of the present invention, when using 180 to 220 parts by weight of rapid-hardening cement mortar, the amount of water added during mixing is 20 to 30 parts.

[0048] In one embodiment of the present invention, when using rapid-hardening cement mortar, the rapid-hardening cement mortar contains 75 parts of rapid-hardening sulfoaluminate cement, 25 parts of ordinary Portland cement, and 100 parts of aggregate; when using rapid-hardening cement mortar with a mass fraction of 220 parts, the amount of water added during mixing is 30 parts.

[0049] To further illustrate the present invention, the following describes in detail, with reference to embodiments, a rapid-hardening cement mortar and its application method provided by the present invention. Example 1

[0050] This application discloses a rapid-hardening cement mortar, which is composed of the following components in parts by weight: 75 parts rapid-hardening sulfoaluminate cement, 25 parts ordinary Portland cement, 100 parts aggregate, 1.39 parts admixture, 2 parts galvanized steel fiber, and 1 part PVA fiber.

[0051] The aggregate is ordinary construction river sand or manufactured sand. Admixtures include 0.5 parts polycarboxylate superplasticizer, 0.44 parts tartaric acid retarder, 0.4 parts early-strength agent, and 0.05 parts defoamer. The selected galvanized steel fibers are 15mm long, 0.2mm in diameter, and have a zinc coating thickness of 0.5μm; the PVA fibers are 5mm long and 25μm in diameter.

[0052] This embodiment sets up multiple treatment groups and control groups, and designs different fiber composition modification schemes. The fiber composition modification process involves: impregnating the fiber composition in a silane coupling agent and then drying it to form a corresponding film; then, depending on specific requirements, impregnating it in another silane coupling agent and drying it again. The specific operation of the cement mortar application process is as follows: according to the fiber composition design scheme in the table below, weigh the above-mentioned components of rapid-hardening cement mortar, add 30 parts of water, stir evenly to form the corresponding cement block, let it cure for 2 hours, and test its 2-hour compressive strength, 2-hour flexural strength, and the relative shrinkage reduction value K of the cement after 4 hours.

[0053] The method for assessing the shrinkage reduction of cement blocks was as follows: A blank group was set up, using cement mortar composed of 75 parts rapid-hardening sulfoaluminate cement, 25 parts ordinary Portland cement, 100 parts aggregate, and 1.39 parts admixture, without any fiber composition. After the above composition was mixed evenly, 30 parts of water were added, and the mixture was stirred evenly to form the corresponding cement blocks. The length shrinkage L0 of the blank group cement blocks was measured after molding and 4 hours later. For different treatment groups and control groups, the length shrinkage L0 of the cement blocks after molding and 4 hours later was measured. i Therefore, the relative value of its contraction decrease, K, is calculated as K = (L0 - L i ) / L0.

[0054] The specific results of the treatment group, control group, and blank group in this embodiment are shown in Table 1 below.

[0055] Table 1. Test results of different modification schemes and their corresponding cement blocks

[0056] Serial Number | Modification Treatment | 2-Hour Compressive Strength (MPa) | 2-Hour Flexural Strength (MPa) | 4-Hour Shrinkage Reduction | K Treatment Group A1: Fiber composition impregnated with coupling agents aminopropyltriethoxysilane and diamino functional group silane sequentially, then dried. | 28.6 | 3.4 | 6.89% Treatment Group A2: Fiber composition impregnated with coupling agent aminopropyltriethoxysilane only, then dried. | 26.0 | 3.1 | 2.71% Treatment Group A3: Fiber composition impregnated with diamino functional group silane only, then dried. | 24.3 | 2.9 | 2.70% Control Group A1: Fiber composition not modified with silane coupling agent. | 24.1 | 2.5 | 1.61% Blank Group: No fiber composition added. | 26.3 | 7.2 | 6.30

[0057] It can be seen that, compared with the control group A1, the treatment groups A1~A3, after being modified with silane coupling agents, have better overall compressive strength, flexural strength and relative shrinkage reduction; moreover, the anti-shrinkage effect of the fiber composition is greatly improved after being modified with two different silane coupling agent schemes. Example 2

[0058] This application discloses a rapid-hardening cement mortar, which is composed of the following components in parts by weight: 75 parts of rapid-hardening sulfoaluminate cement, 25 parts of ordinary Portland cement, 100 parts of aggregate, 1.39 parts of admixture, 2 parts of galvanized steel fiber, and 1 part of polymer fiber. The galvanized steel fiber and polymer fiber are impregnated with coupling agents aminopropyltriethoxysilane and diamino functional group silane respectively and then dried.

[0059] The additives include 0.5 parts polycarboxylate superplasticizer, 0.44 parts tartaric acid retarder, 0.4 parts early strength agent, and 0.05 parts defoamer. The galvanized steel fibers are 15 mm long, 0.2 mm in diameter, and the zinc coating is 0.5 μm thick.

[0060] This embodiment sets up multiple treatment groups and control groups, designs different fiber composition combination schemes, and calculates the average preload coefficient of polymer fibers. The specific operation of the cement mortar application process is as follows: According to the fiber composition design scheme in the table below, weigh the above-mentioned components of rapid-hardening cement mortar, add 30 parts of water, stir evenly to form the corresponding cement block, let it cure for 2 hours, and test its 2-hour compressive strength, 2-hour flexural strength, and the relative shrinkage reduction value K of the cement after 4 hours. The test method for the relative shrinkage reduction value K can be found in Example 1.

[0061] The specific results of the treatment group, control group, and blank group in this embodiment are shown in Table 2 below.

[0062] Table 2 Test results of different modification schemes and their corresponding cement blocks

[0063] Serial Number Polymer Fiber Treatment Scheme Elastic Modulus E (GPa) Coefficient of Thermal Expansion α (10-6 / ℃) Average preload coefficient (Pa / ℃) 4-hour shrinkage reduction relative value K Treatment group B1 PVA polyvinyl alcohol fiber 35 150 5250 89% Treatment group B2 PVA fiber and PAN fiber, with a mass ratio of 0.8:0.2 / / 420 378% Treatment group B3 PVA fiber and PET fiber, with a mass ratio of 0.7:0.3 / / 3720 74% Control group B1 PP polypropylene fiber 6100 600 63% Control group B2 PAN polyacrylonitrile fiber 91.5 13.5 25% Control group B3 PET polyester fiber 350 150 47% Control group B4 PA6 polyamide fiber 2~445 90~180 52% Blank group cement substrate 20 10NA 0%

[0064] It can be seen that, from the perspective of anti-shrinkage effect, the scheme using a single PVA fiber in treatment group B1 has the best performance; using PVA fiber and PAN fiber, as well as PVA fiber and PET fiber, can also achieve a certain anti-shrinkage effect.

[0065] Thus, by controlling the average preload coefficient of polymer fibers in cement blocks, this invention can better utilize the heat of hydration released by cement to increase the elongation and deformation of polymer fibers, and better utilize the local stress generated during cooling. Furthermore, by controlling the average preload coefficient of polymer fibers in cement blocks, the amount of polymer fibers used can be greatly reduced. Example 3

[0066] This application discloses a rapid-hardening cement mortar, which is composed of the following components in parts by weight: 75 parts of rapid-hardening sulfoaluminate cement, 25 parts of ordinary Portland cement, 100 parts of aggregate, 1.39 parts of admixture, and several parts of fiber composition. The galvanized steel fiber and polymer fiber are impregnated with coupling agent aminopropyltriethoxysilane and diamino functional group silane respectively and then dried.

[0067] The additives include 0.5 parts of polycarboxylate superplasticizer, 0.44 parts of tartaric acid retarder, 0.4 parts of early strength agent, and 0.05 parts of defoamer. The fiber composition consists of galvanized steel fibers and polymer fibers. The galvanized steel fibers are 15 mm long, 0.2 mm in diameter, and have a zinc coating thickness of 0.5 μm; the PVA fibers are 5 mm long and 25 μm in diameter.

[0068] This embodiment sets up multiple treatment groups and control groups, adjusting the amount of galvanized steel fiber and PVA fiber added, as well as the water content of the rapid-hardening cement mortar. The specific operation of the cement mortar application process is as follows: According to the design scheme in the table below, weigh the rapid-hardening cement mortar of the above components, add a certain amount of water, stir evenly to form the corresponding cement blocks, let them cure for 2 hours, and test their 2-hour compressive strength and 2-hour flexural strength, as well as the relative shrinkage reduction value K of the cement after 4 hours. The test method for the relative shrinkage reduction value K can be found in Example 1.

[0069] The specific results of the treatment group, control group, and blank group in this embodiment are shown in Table 3 below.

[0070] Table 3 Test results of different modification schemes and their corresponding cement blocks

[0071] Serial Number | Galvanized Steel Fiber Addition (parts) | PVA Fiber Addition (parts) | Water Consumption (parts) | 2-Hour Compressive Strength (MPa) | 2-Hour Flexural Strength (MPa) | 4-Hour Shrinkage Reduction | K | Blank Group | 0 | 0 | 26 | 26.37 | 2.630 | Treatment Group C1 | 10 | 26 | 25.21 | 2.84 | 13% | Treatment Group C2 | 20 | 26 | 27.9 | 3.76 | 14% | Treatment Group C3 | 30 | 27 | 21.30 | 2.77 | 12% | Treatment Group C4 | 40 | 28 | 15.0 21.9113% Treatment Group C50 0.52 62 5.41 2.56 76% Treatment Group C60 12 62 4.6 2.75 80% Treatment Group C70 1.52 72 1.5 2.67 71% Treatment Group C80 22 81 8.9 1.99 58% Treatment Group C9 20.52 62 6.9 3.02 88% Treatment Group C10 21 2 62 8.6 3.46 89% Treatment Group C11 21 2 72 5.5 2.85 81%

[0072] This revealed that treatment groups C1-C4, using only galvanized steel fibers, required increased water content during cement mortar application to maintain its fluidity. Otherwise, the material would compromise filling density and shorten setting time, impacting construction. This is because the fibers themselves increase slurry viscosity, and their surface absorbs water, further deteriorating fluidity. Compared to control group C1, treatment groups C1-C4, simply increasing the amount of galvanized steel fibers, did not significantly improve compressive and flexural strength; instead, the forced increase in water content worsened these properties. While maintaining a certain level of fluidity, increasing water content significantly deteriorated compressive and flexural strength, even while improving flowability. Furthermore, in early-strength systems, water content significantly affects various indicators; therefore, the optimal approach is to use as little water as possible while maintaining a certain level of fluidity.

[0073] Secondly, comparing treatment groups C1-C4 and treatment groups C5-C8, the addition of only PVA fibers significantly improved compressive strength, flexural strength, and cement shrinkage reduction compared to the addition of only galvanized steel fibers. Furthermore, as the amount of PVA fibers increased, the slurry fluidity decreased, and the improvement in compressive and flexural strength was only moderate.

[0074] Furthermore, compared to treatment groups C1-C4 and C5-C8, treatment groups C9-C11, employing a composite scheme of galvanized steel fiber and PVA fiber, showed the most significant improvement in overall compressive strength, flexural strength, and reduction in cement shrinkage. Moreover, by rationally controlling the ratio of galvanized steel fiber to PVA fiber and the overall water consumption, treatment group C10 achieved the optimal solution. Its fiber composition dosage, compared to the sum of rapid-hardening sulfoaluminate cement and ordinary Portland cement, was only 3:100. This extremely low fiber composition dosage ensured excellent compressive and flexural strength, resulting in cement blocks with a compressive strength ≥20 MPa formed by treatment group C10.

[0075] The above are merely embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A rapid-hardening cement mortar, characterized in that, The rapid-hardening cement mortar is composed of the following components in parts by weight: The mixture comprises 60-90 parts of rapid-hardening sulfoaluminate cement, 10-40 parts of ordinary Portland cement, 80-120 parts of aggregate, 0.5-3 parts of admixture, and 0.5-4 parts of fiber composition; wherein the fiber composition comprises galvanized steel fiber and polymer fiber, and the polymer fiber comprises PVA fiber. Wherein, the average preload coefficient of the polymer fiber The range is 3000 Pa / ℃ to 6000 Pa / ℃, with an average preload coefficient. The calculation method is as follows: ;in, For the first The mass fractions corresponding to each polymer fiber; For the first The elastic modulus corresponding to each polymer fiber; For the first The coefficient of thermal expansion of each polymer fiber; n is the number of types of polymer fibers; For loop variable, =1，2，...，n； The galvanized steel fiber and polymer fiber have a silane coupling agent modified film layer on their surface; the surface film layer of the galvanized steel fiber and polymer fiber is a composite film layer modified by aminopropyltriethoxysilane and diamino functional group silane; and / or, the modification process of the galvanized steel fiber and polymer fiber is to first impregnate with diamino functional group silane and then dry, and then impregnate with aminopropyltriethoxysilane and then dry.

2. The rapid-hardening cement mortar according to claim 1, characterized in that, Polymer fibers also include at least one of PP fiber, PAN fiber, PET fiber or PA6 fiber.

3. The rapid-hardening cement mortar according to claim 1, characterized in that, The length ratio of the galvanized steel fiber to the polymer fiber is (2~4):1; and / or, the fiber length of the galvanized steel fiber is 12mm~18mm, and the length of the polymer fiber is 3mm~8mm.

4. The rapid-hardening cement mortar according to claim 3, characterized in that, The galvanized steel fiber is 15mm long, and the polymer fiber is 5mm long.

5. The rapid-hardening cement mortar according to claim 1, characterized in that, The mass ratio of the fiber composition to the total amount of rapid-hardening sulfoaluminate cement and ordinary Portland cement is (2~4):100; and / or, the mass ratio of the galvanized steel fiber to the polymer fiber is (1~3):(0.5~1.5).

6. The rapid-hardening cement mortar according to claim 1, characterized in that, The zinc layer thickness in the galvanized steel fiber is 0.2μm~0.6μm.

7. A rapid-hardening cement mortar according to any one of claims 1 to 6, characterized in that, The rapid-hardening cement mortar is composed of the following components in parts by weight: 70-80 parts rapid-hardening sulfoaluminate cement, 20-30 parts ordinary Portland cement, 90-110 parts aggregate, 1-3 parts galvanized steel fiber, 0.5-2 parts PVA fiber, and 1-2 parts admixture.

8. The rapid-hardening cement mortar according to claim 7, characterized in that, The rapid-hardening cement mortar is composed of the following components in parts by weight: 75 parts rapid-hardening sulfoaluminate cement, 25 parts ordinary Portland cement, 100 parts aggregate, 2 parts galvanized steel fiber, 1 part PVA fiber, and 1.39 parts admixture.

9. The method for applying a rapid-hardening cement mortar according to any one of claims 1 to 8, characterized in that, Weigh the quick-hardening cement mortar according to the mass ratio, add water and mix thoroughly.

10. The application method of a rapid-hardening cement mortar according to claim 9, characterized in that, When using 180 to 220 parts by weight of the aforementioned rapid-hardening cement mortar, the amount of water added during mixing is 20 to 30 parts.

Images