Quick-reinforcing early-strength repairing type mortar and preparation method thereof

Abstract

The invention belongs to the technical field of gel materials, and mainly provides rapid-reinforcing early-strength repairing type mortar and a preparation method thereof.The preparation method comprises the following steps that metering and even mixing are conducted, specifically, rapid-hardening sulphoaluminate cement, Portland cement and fly ash are weighed and evenly premixed, and a gelling component A is obtained; weighing steel slag and quartz sand, and uniformly mixing to obtain an aggregate component B; weighing a water reducing agent, an early strength agent, a retarder and half of the total weight of water, and uniformly mixing to obtain an admixture component C; stirring: adding the aggregate component B and water accounting for 1 / 4 of the total weight, rapidly mixing and stirring, adding the gelling component A, continuously stirring, adding the additive component C and water accounting for 1 / 4 of the total weight, and continuously stirring, so as to prepare the rapidly-reinforced early-strength repair mortar. And molding and curing. The uniformity is improved through grouping premixing, the interface bonding performance is improved through staged stirring, the defects of insufficient early strength caused by uneven components, poor interface, slow hydration and the like in traditional preparation are overcome, and the early strength advantage is fully exerted.

Description

A rapid-strength, early-strength repair mortar and its preparation method Technical Field

[0001] This invention belongs to the field of gel material technology, and in particular relates to a rapid reinforcement and early strength repair mortar and its preparation method. Background Technology

[0002] In emergency repair and reinforcement projects for infrastructure such as transportation hubs, industrial plants, bridges, and tunnels, the early strength of repair materials directly determines the efficiency and economic cost of project restoration. Traditional repair mortars generally use ordinary Portland cement as the core base material, which has a slow hydration reaction rate and lags in early strength development, becoming a core technical bottleneck restricting the timeliness of emergency repair projects.

[0003] From the perspective of actual engineering needs, many current infrastructure projects suffer from problems such as concrete spalling, crack expansion, and decreased structural load-bearing capacity due to long-term service, load impact, or environmental erosion, requiring rapid repair to restore functionality. For example, repairing potholes on highways requires minimizing closure time to avoid causing widespread traffic congestion; repairing damaged foundations in industrial plants requires quickly meeting equipment installation load requirements to reduce production interruption losses. However, traditional repair mortars based on ordinary silicate cement are completely unable to meet the core requirement of rapid load-bearing in these projects, leading to prolonged restoration cycles and significantly increased indirect economic losses.

[0004] From the perspective of the limitations of existing improvement technologies, although the industry has proposed various optimization solutions to address the problem of insufficient early strength, all of them have obvious shortcomings. Some solutions accelerate cement hydration by adding chloride or sulfate early-strength agents, but chlorides accelerate steel corrosion, and sulfates easily cause cement stone to expand and crack in the later stages, significantly reducing structural durability and making them unsuitable for reinforced concrete structures or long-term service projects. Other solutions improve early strength by optimizing aggregate gradation or increasing cement content, but this leads to decreased mortar fluidity, increased construction difficulty, and excessive cement content can exacerbate drying shrinkage, causing new crack risks, while also failing to meet the development requirements of green building materials for carbon reduction and emission reduction.

[0005] In summary, the insufficient early strength of traditional cement-based materials has created a significant contradiction with the current engineering demands for rapid infrastructure repair and efficient reinforcement. Existing improvement solutions struggle to achieve a balance between early strength, durability, workability, and cost-effectiveness. Therefore, developing a repair mortar that overcomes the hydration rate limitations of ordinary Portland cement, significantly improves early strength development speed while ensuring later-stage strength and durability, and simultaneously considers ease of construction and cost control, has become an urgent need to address the technical bottlenecks of traditional cement-based materials. This has significant engineering value for improving infrastructure repair efficiency and reducing total life-cycle costs. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a rapid reinforcement and early strength repair mortar and its preparation method, so as to solve the problem of insufficient early strength of traditional cement-based materials in the prior art.

[0007] To achieve the above and other related objectives, the first aspect of the present invention provides a rapid-strength, early-hardening repair mortar, comprising the following components by weight: 40-60 parts rapid-hardening sulfoaluminate cement, 340-400 parts silicate cement, 1800 parts steel slag, 40 parts fly ash, 400 parts quartz sand, 1-7 parts water-reducing agent, 0.1-2.0 parts early-strength agent, 0.1-2.0 parts retarder, and 120-200 parts water.

[0008] In some embodiments of the present invention, the rapid-hardening sulfoaluminate cement is 42.5 rapid-hardening sulfoaluminate cement.

[0009] In some embodiments of the present invention, the silicate cement is PC42.5 silicate cement.

[0010] In some embodiments of the present invention, the water is industrial tap water.

[0011] In some embodiments of the present invention, the particle size of the steel slag is 0.8-3 mm.

[0012] In some embodiments of the present invention, the specific surface area of ​​fly ash is ≥250 m². 2 / kg, 28d activity index ≥70%.

[0013] In some embodiments of the present invention, the quartz sand particle size is 40-70 μm.

[0014] In some embodiments of the present invention, the water-reducing agent is one of a polycarboxylate-based high-performance water-reducing agent or a naphthalene-based high-efficiency water-reducing agent.

[0015] In some embodiments of the present invention, the early strength agent is one of calcium formate or sodium sulfate / triethanolamine composite early strength agent.

[0016] In some embodiments of the present invention, the retarder is one of sodium gluconate or citric acid / tartaric acid composite retarder.

[0017] The second aspect of this invention provides a method for preparing the above-mentioned rapid-strength, early-strength repair mortar, comprising the following steps: Step 1: Measuring and mixing: Weighing rapid-hardening sulfoaluminate cement, silicate cement, and fly ash according to a predetermined ratio, and pre-mixing them evenly to obtain cementitious component A; weighing steel slag and quartz sand according to a predetermined ratio and mixing them evenly to obtain aggregate component B; weighing water-reducing agent, early-strength agent, retarder, and half the total weight of water according to a predetermined ratio and mixing them evenly to obtain admixture component C; Step 2: Stirring: Adding aggregate component B and one-quarter of the total weight of water, quickly mixing and stirring, then adding cementitious component A and continuing stirring, then adding admixture component C and one-quarter of the total weight of water and continuing stirring to obtain rapid-strength, early-strength repair mortar; Step 3: Molding: Sending the stirred material into a mortar mold to prepare mortar test blocks; Step 4: Curing: Placing the mortar test blocks along with the mortar mold into a curing kiln for curing.

[0018] In some embodiments of the present invention, the stirring in step two is carried out in a small horizontal mixer at a stirring speed of 60-80 r / min.

[0019] In some embodiments of the present invention, in step two, after adding component B, the aggregate is quickly mixed and stirred for 10-15 seconds to wet the surface of the aggregate.

[0020] In some embodiments of the present invention, in step two, after adding component A, stirring is continued for 15-20 seconds.

[0021] In some embodiments of the present invention, in step two, after adding component C, stirring is continued for 25-30 seconds.

[0022] In some embodiments of the present invention, in step three, the stirred material is fed into a 40*40*160 mm mortar mold to prepare a mortar test block.

[0023] In some embodiments of the present invention, in step four, during curing, the temperature is controlled at 20±1℃ and the relative humidity is ≥90%.

[0024] As described above, the present invention has the following beneficial effects: 1. The combination of rapid-hardening sulfoaluminate cement and silicate cement retains the early strength advantage of rapid-hardening sulfoaluminate cement while ensuring the stability of later strength through silicate cement, avoiding the problem of reduced later strength of single rapid-hardening sulfoaluminate cement; 2. The use of a high proportion of steel slag and quartz sand as aggregates, where steel slag itself has high strength and dense structure, and quartz sand has uniform particles and good wear resistance, allows the high-density aggregate to quickly build a stable physical skeleton in the early stage of mortar setting, reducing internal pores and weak points, allowing the early-formed hydration products to quickly transfer stress through the skeleton, thereby improving early compressive and flexural strength; 3. The early-strength agent accelerates the cement hydration reaction rate and promotes the hydration products... Rapid formation of hydration products shortens the strength development cycle, allowing the mortar to reach the required early strength in a short time. Water-reducing agents reduce the amount of mixing water, lower the internal porosity of the mortar, and make the early hydration products denser, avoiding the weakening of early strength caused by pores formed after excessive water evaporation. Retarder regulates the hydration reaction rhythm, ensuring uniform formation of hydration products, reducing internal stress and microcracks, and ensuring stable early strength development. Fly ash, as an active admixture, can participate in the hydration reaction early, generating additional hydration products to fill internal pores, further improving early structural density and strength. Fly ash also improves mortar workability, allowing the components to mix more evenly and avoiding weak early strength areas caused by insufficient local hydration. Detailed Implementation

[0025] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0026] The first aspect of this invention provides a rapid-strength, early-hardening repair mortar, comprising the following components by weight: 40-60 parts rapid-hardening sulfoaluminate cement, 340-400 parts silicate cement, 1800 parts steel slag, 40 parts fly ash, 400 parts quartz sand, 1-7 parts water-reducing agent, 0.1-2.0 parts early-strength agent, 0.1-2.0 parts retarder, and 120-200 parts water.

[0027] Rapid-hardening sulfoaluminate cement sets quickly after pouring, forming a dense early structure that compensates for the slow early strength development of silicate cement. The combination of rapid-hardening sulfoaluminate cement and silicate cement retains the early strength advantage of rapid-hardening sulfoaluminate cement while ensuring later strength stability through silicate cement, thus avoiding the problem of reduced strength in the later stages associated with using rapid-hardening sulfoaluminate cement alone.

[0028] A high proportion of steel slag and quartz sand is selected as aggregates. Steel slag itself has high strength and dense structure, while quartz sand has uniform particles and good wear resistance. The high-density aggregate can quickly build a stable physical skeleton in the early stage of mortar setting, reduce internal porosity and weak points, and allow early-formed hydration products to quickly transfer stress through the skeleton, thereby improving early compressive and flexural strength.

[0029] Early-strength agents accelerate the cement hydration reaction rate, promote the rapid formation of hydration products, and shorten the strength development cycle, allowing mortar to reach the required early strength in a short time. Water-reducing agents reduce the amount of mixing water, lower the internal porosity of the mortar, and make the early hydration products denser, preventing the formation of pores after excessive water evaporation from weakening early strength. Retardering agents regulate the hydration reaction rhythm, ensuring uniform formation of hydration products, reducing internal stress and microcracks, and guaranteeing stable early strength development.

[0030] Fly ash, as an active admixture, is selected with a high-activity grade. It can participate in the hydration reaction early on, generating additional hydration products to fill internal pores, further improving early structural density and strength. Furthermore, fly ash improves mortar workability, allowing for more uniform mixing of components and preventing weak early-strength areas caused by insufficient local hydration.

[0031] In some embodiments of the present invention, the rapid-hardening sulfoaluminate cement is 42.5 grade rapid-hardening sulfoaluminate cement. When 42.5 grade rapid-hardening sulfoaluminate cement is combined with silicate cement, it can ensure high early strength while reducing the risk of later strength reduction.

[0032] In some embodiments of the present invention, the silicate cement is PC42.5 silicate cement. The 42.5 strength grade is highly compatible with 42.5 rapid-hardening sulfoaluminate cement, ensuring that insufficient strength does not slow down early strength development, nor does excessive strength lead to an unbalanced hydration rate. The combination of rapid-hardening sulfoaluminate cement and silicate cement improves mortar mixing, allowing aggregates and admixtures to disperse evenly, ensuring that early hydration products form a uniform and dense structure, and avoiding localized weakness.

[0033] In some embodiments of the present invention, the water is industrial tap water. Industrial tap water is readily available and cost-effective, meeting the needs of industrial production, and ensuring that the early strength performance remains controllable when the formula moves from the laboratory to practical application.

[0034] In some embodiments of the present invention, the steel slag particle size is 0.8-3 mm, and the quartz sand particle size is 40-70 μm. The steel slag particle size range falls within a reasonable range for coarse aggregate, and the quartz sand particle size range falls within a reasonable range for fine aggregate. Quartz sand can fill the macroscopic voids between steel slag particles and the microscopic pores formed during the hydration process of cementitious materials. This ensures both the packing density between particles and the complementary coarse-fine gradation with the fine aggregate quartz sand, filling voids, reducing the internal porosity of the mortar, and making the early strength effect more controllable. The steel slag particle size can be any of the following: 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, and 3.0mm. The quartz sand particle size can be 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, and 70μm.

[0035] In some embodiments of the present invention, the specific surface area of ​​fly ash is ≥250 m². 2 / kg, 28-day activity index ≥70%. Large specific surface area increases the contact area between fly ash and cement hydration products, accelerating secondary hydration reactions and allowing fly ash to generate a large amount of hydration products in the early stages, filling the micropores inside the mortar and improving early structural density. A high 28-day activity index ensures that fly ash possesses sufficient chemical reactivity, allowing admixtures to truly participate in early strength development. Specifically, the specific surface area of ​​fly ash can be 250m². 2 / kg, 260m 2 / kg, 270m 2 / kg, 280m 2 / kg and above. The 28-day activity index can be 70%, 75%, 80%, 85%, 90%, 95%, or 100%.

[0036] In some embodiments of the present invention, the water-reducing agent is one of a polycarboxylate-based high-performance water-reducing agent or a naphthalene-based high-efficiency water-reducing agent. The polycarboxylate-based high-performance water-reducing agent reduces internal porosity without inhibiting early-strength hydration; instead, it makes the hydration products denser, directly improving early strength. The naphthalene-based high-efficiency water-reducing agent avoids localized strength weakness caused by aggregate agglomeration in the early stages of mortar setting, and its early strength improvement rate is stable.

[0037] In some embodiments of the present invention, the early-strength agent is either calcium formate or a sodium sulfate / triethanolamine composite early-strength agent. Calcium formate is chloride-free, non-corrosive to steel reinforcement, and can still efficiently accelerate hydration at low temperatures, promoting the rapid formation of ettringite while avoiding the corrosion risks of traditional chloride-based early-strength agents. The sodium sulfate / triethanolamine composite early-strength agent exhibits a significant synergistic effect; sodium sulfate accelerates the formation of hydration products, while triethanolamine promotes the dispersion of cement particles. The combination of the two allows the mortar to quickly reach its designed early strength. In the sodium sulfate / triethanolamine composite early-strength agent, the mass ratio of sodium sulfate to triethanolamine can be adjusted between 4:6 and 7:3 according to actual usage.

[0038] In some embodiments of the present invention, the retarder is either sodium gluconate or a citric acid / tartaric acid composite retarder. Sodium gluconate has a mild retarding effect and good compatibility with accelerators. It can inhibit the reaction between rapid-hardening sulfoaluminate cement and accelerators, extending workability without weakening early strength development and avoiding strength lag caused by excessive retarding. The combination of citric acid / tartaric acid composite retarder avoids the problem of insufficient or excessive effect of a single retarder under extreme conditions, ensuring uniform generation of hydration products and reducing internal microcracks. In the citric acid / tartaric acid composite retarder, the mass ratio of citric acid to tartaric acid can be adjusted between 2:8 and 7:3 according to actual application.

[0039] The second aspect of this invention provides a method for preparing the above-mentioned rapid-strength, early-strength repair mortar, comprising the following steps: Step 1: Measuring and mixing: Weighing rapid-hardening sulfoaluminate cement, silicate cement, and fly ash according to a predetermined ratio, and premixing them uniformly to obtain cementitious component A. Cementitious component A is premixed separately to ensure that the rapid-hardening sulfoaluminate cement and silicate cement are evenly dispersed, and that the fly ash is fully integrated into the cementitious system, ensuring that the hydration reaction starts simultaneously and avoiding localized weak early strength due to uneven distribution of cementitious materials. Weighing steel slag and quartz sand according to a predetermined ratio and mixing them uniformly to obtain aggregate component B. Aggregate component B ensures uniform gradation of coarse and fine aggregates and avoids localized accumulation of steel slag or quartz sand, laying the foundation for the subsequent rapid construction of a stable strength skeleton. Weighing water-reducing agent, early-strength agent, retarder, and half the total weight of water according to a predetermined ratio and mixing them uniformly to obtain admixture component C. Admixture component C is first evenly dispersed in water to avoid excessively high or low local concentrations of the admixture caused by direct dry mixing. This ensures that the admixture is well-matched with cementitious materials and aggregates to maximize the synergistic effects of early strength, water reduction, and retarding.

[0040] Step Two: Mixing: Start the small horizontal mixer and set the speed to 60-80 rpm. Then add aggregate component B and one-quarter of the total weight of water, and quickly mix for 10-15 seconds to wet the surface of the aggregate material. Pre-absorbing water on the aggregate surface prevents excessive water absorption when it comes into contact with the cementitious material, which could lead to hydration dehydration. A wet aggregate surface also makes it easier for the aggregate to bond with the cementitious material, improving interfacial adhesion and reducing the risk of early interfacial delamination. The speed of the small horizontal mixer can be 60 rpm, 65 rpm, 70 rpm, 75 rpm, or 80 rpm. After adding aggregate component B, the mixing time can be 10 seconds, 11 seconds, 12 seconds, 13 seconds, 14 seconds, or 15 seconds.

[0041] Add cementitious component A and continue stirring for 15-20 seconds to ensure the cementitious material fully coats the surface of the aggregate. This forms a uniform coating on the wet aggregate surface, preventing the cementitious material from clumping together when exposed to water and ensuring that each aggregate particle is tightly coated with the hydration products. The stirring time after adding aggregate component A can be 15, 16, 17, 18, 19, or 20 seconds.

[0042] Next, add admixture component C and one-quarter of the total weight of water and continue stirring for 25-30 seconds. During this time, the admixture solution can evenly penetrate the system, regulating the hydration reaction rhythm. Simultaneously, the water replenishment process avoids uneven early water distribution, further reducing internal porosity and making the early structure denser, thus obtaining a rapidly reinforced, early-strength repair mortar. Adding water in batches avoids the water-cement ratio imbalance caused by adding water all at once. This ensures sufficient water for the cementitious material to hydrate fully while reducing free water content through multiple small additions, preventing the formation of numerous pores after water evaporation. This allows early hydration products to fill more space, improving structural density. The stirring time after adding aggregate component C can be 25 seconds, 26 seconds, 27 seconds, 28 seconds, 29 seconds, or 30 seconds.

[0043] Step 3: Molding: The mixed material is fed into a 40*40*160mm mortar mold to prepare mortar test blocks.

[0044] Step Four: Curing: Place the mortar test blocks along with the mortar molds into a curing kiln for curing. During curing, control the temperature at 20±1℃ and the relative humidity at ≥90%. A stable temperature allows the hydration reaction of the cementitious materials to proceed synchronously, uniformly generating early-strength hydration products and ensuring uniform early strength of the test blocks. A high-humidity environment prevents excessive evaporation of moisture from the mortar test block surface, providing sufficient moisture for cement hydration. This avoids surface cracking and sandblasting caused by insufficient humidity in traditional curing methods, reducing weak points in the early structure. Simultaneously, high humidity allows the secondary hydration reaction of fly ash to start early, generating more hydration products to fill pores and further improving the density of the early structure. The curing temperatures can be 19℃, 20℃, or 21℃. The curing humidity can be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%.

[0045] The following detailed description of specific embodiments of the present invention, in conjunction with preferred embodiments, further illustrates the relevant details. When numerical ranges are given in the embodiments, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range, as well as any value between the two endpoints, may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by those skilled in the art. In addition to the specific methods, devices, and materials used in the embodiments, the present invention can be implemented using any prior art methods, devices, and materials similar to or equivalent to those described in the embodiments of the present invention, provided that those skilled in the art possess the prior art and the description of the present invention.

[0046] The components, raw materials, and related parameters used in the following examples and comparative examples are as follows: 42.5 rapid-hardening sulfoaluminate cement, Shanghai Baoshan Sanxiong Waterproof Materials Factory; PC42.5 silicate cement, Anhui Conch Cement Co., Ltd.; steel slag, 0.8-3mm, provided by Shanghai MCC Environmental Engineering Technology Co., Ltd.; fly ash: specific surface area ≥250m². 2 / kg, 28d activity index ≥70%, provided by Shanghai Zhongye Environmental Engineering Technology Co., Ltd.; Quartz sand: 40-70μm, Tianjin Guangfu Technology Development Co., Ltd.; Polycarboxylate-based high-performance water-reducing agent: Shanghai Chengjian Materials Co., Ltd.; Naphthalene-based high-efficiency water-reducing agent: Shanghai Chengjian Materials Co., Ltd.; Calcium formate: Laiyang Hongxiang Building Admixture Factory; Sodium sulfate / triethanolamine composite early strength agent: Laiyang Hongxiang Building Admixture Factory; Sodium gluconate: Shanxi Feike New Material Technology Co., Ltd.; Citric acid / tartaric acid composite retarder: Shanxi Feike New Material Technology Co., Ltd.; Water: Industrial tap water, conforming to JGJ 63 standard for concrete mixing water.

[0047] Example 1: A rapid-strength, early-hardening repair mortar, comprising the following components by weight: 40 parts of 42.5 rapid-hardening sulfoaluminate cement, 360 parts of PC42.5 silicate cement, 1800 parts of steel slag with a particle size of 0.8-2mm, 40 parts of fly ash, 400 parts of quartz sand with a particle size of 40-60μm, 3 parts of polycarboxylate-based high-performance water-reducing agent, 0.2 parts of calcium formate as an early-strength agent, 0.2 parts of sodium gluconate as a retarder, and 180 parts of water.

[0048] A method for preparing the above-mentioned rapid reinforcement and early strength repair mortar includes the following steps: Step 1: Measuring and mixing: Weigh 42.5 rapid hardening sulfoaluminate cement, PC42.5 silicate cement and fly ash according to a predetermined ratio, and premix them evenly to obtain cementitious component A; Weigh 0.8-2mm steel slag and 40-60μm quartz sand according to a predetermined ratio and mix them evenly to obtain aggregate component B; Weigh polycarboxylate-based high-performance water-reducing agent, calcium formate, sodium gluconate and half the total weight of water according to a predetermined ratio and mix them evenly to obtain admixture component C.

[0049] Step 2: Mixing: Start the small horizontal mixer and set the speed to 65 r / min. Then add aggregate component B and one-quarter of the total weight of water. Mix quickly for 10 seconds to wet the surface of the aggregate material. Then add cementitious component A and continue mixing for 15 seconds to fully coat the surface of the aggregate material. Then add admixture component C and one-quarter of the total weight of water and continue mixing for 30 seconds to obtain the rapid reinforcement and early strength repair mortar.

[0050] Step 3: Molding: The mixed material is fed into a 40*40*160 mm mortar mold to prepare mortar test blocks.

[0051] Step 4: Curing: Place the mortar test block and mortar mold into the curing kiln for curing. The curing temperature is controlled at 21℃ and the relative humidity is ≥90%.

[0052] Example 2: A rapid-strength, early-hardening repair mortar, comprising the following components by weight: 60 parts of 42.5 rapid-hardening sulfoaluminate cement, 340 parts of PC42.5 silicate cement, 1800 parts of steel slag with a particle size of 1-3 mm, 40 parts of fly ash, 400 parts of quartz sand with a particle size of 50-70 μm, 3 parts of naphthalene-based high-efficiency water-reducing agent, 0.2 parts of sodium sulfate / triethanolamine composite early-strength agent, 0.2 parts of citric acid / tartaric acid composite retarder, and 180 parts of water.

[0053] A method for preparing the above-mentioned rapid reinforcement and early strength repair mortar includes the following steps: Step 1: Measuring and mixing: Weigh 42.5 rapid hardening sulfoaluminate cement, PC42.5 silicate cement, and fly ash according to a predetermined ratio, and premix them evenly to obtain cementitious component A; Weigh 1-3mm steel slag and 50-70μm quartz sand according to a predetermined ratio and mix them evenly to obtain aggregate component B; Weigh naphthalene-based high-efficiency water-reducing agent, sodium sulfate / triethanolamine composite early strength agent, citric acid / tartaric acid composite retarder, and half the total weight of water according to a predetermined ratio and mix them evenly to obtain admixture component C.

[0054] Step 2: Mixing: Start the small horizontal mixer and set the speed to 75 r / min. Then add aggregate component B and one-quarter of the total weight of water. Mix quickly for 15 seconds to wet the surface of the aggregate material. Then add cementitious component A and continue mixing for 20 seconds to fully coat the surface of the aggregate material. Then add admixture component C and one-quarter of the total weight of water and continue mixing for 25 seconds to obtain the rapid-strength repair mortar.

[0055] Step 3: Molding: The mixed material is fed into a 40*40*160 mm mortar mold to prepare mortar test blocks.

[0056] Step 4: Curing: Place the mortar test block and mortar mold into the curing kiln for curing. The curing temperature is controlled at 19℃ and the relative humidity is ≥90%.

[0057] Comparative Example 1: A mortar comprising the following components by weight: 40 parts of 42.5 rapid-hardening sulfoaluminate cement, 360 parts of PC42.5 silicate cement, 1800 parts of steel slag with a particle size of 0.8-2 mm, 40 parts of fly ash, 400 parts of quartz sand with a particle size of 40-60 μm, 3 parts of polycarboxylate-based high-performance water-reducing agent, and 180 parts of water.

[0058] A method for preparing the above-mentioned mortar includes the following steps: Step 1: Measuring and mixing: Weigh 42.5 rapid-hardening sulfoaluminate cement, PC42.5 silicate cement and fly ash according to a predetermined ratio, and premix them evenly to obtain cementitious component A; Weigh 0.8-2mm steel slag and 40-60μm quartz sand according to a predetermined ratio and mix them evenly to obtain aggregate component B; Weigh polycarboxylate-based high-performance water-reducing agent and half the total weight of water according to a predetermined ratio and mix them evenly to obtain admixture component C.

[0059] Step 2: Mixing: Start the small horizontal mixer and set the speed to 65 r / min. Then add aggregate component B and one-quarter of the total weight of water. Mix quickly for 10 seconds to wet the surface of the aggregate material. Then add cementitious component A and continue mixing for 15 seconds to fully coat the surface of the aggregate material. Then add admixture component C and one-quarter of the total weight of water and continue mixing for 30 seconds to obtain the mortar in this comparative example.

[0060] Step 3: Molding: The mixed material is fed into a 40*40*160 mm mortar mold to prepare mortar test blocks.

[0061] Step 4: Curing: Place the mortar test block and mortar mold into the curing kiln for curing. The curing temperature is controlled at 21℃ and the relative humidity is ≥90%.

[0062] Comparative Example 2: A mortar comprising the following components by weight: 60 parts of 42.5 rapid-hardening sulfoaluminate cement, 340 parts of PC42.5 silicate cement, 1800 parts of steel slag with a particle size of 1-3 mm, 40 parts of fly ash, 400 parts of quartz sand with a particle size of 50-70 μm, 3 parts of naphthalene-based high-efficiency water-reducing agent, and 180 parts of water.

[0063] A method for preparing the above-mentioned mortar includes the following steps: Step 1: Measuring and mixing: Weigh 42.5 rapid-hardening sulfoaluminate cement, PC42.5 silicate cement and fly ash according to a predetermined ratio, and premix them evenly to obtain cementitious component A; weigh 1-3mm steel slag and 50-70μm quartz sand according to a predetermined ratio and mix them evenly to obtain aggregate component B; weigh naphthalene-based high-efficiency water-reducing agent and half the total weight of water according to a predetermined ratio and mix them evenly to obtain admixture component C.

[0064] Step 2: Mixing: Start the small horizontal mixer and set the speed to 75 r / min. Then add aggregate component B and one-quarter of the total weight of water. Mix quickly for 15 seconds to wet the surface of the aggregate material. Then add cementitious component A and continue mixing for 20 seconds to fully coat the surface of the aggregate material. Then add admixture component C and one-quarter of the total weight of water and continue mixing for 25 seconds to obtain the mortar in this comparative example.

[0065] Step 3: Molding: The mixed material is fed into a 40*40*160 mm mortar mold to prepare mortar test blocks.

[0066] Step 4: Curing: Place the mortar test block and mortar mold into the curing kiln for curing. The curing temperature is controlled at 19℃ and the relative humidity is ≥90%.

[0067] Comparative Example 3: A mortar comprising the following components by weight: 400 parts PC42.5 silicate cement, 1800 parts steel slag with a particle size of 0.8-2 mm, 40 parts fly ash, 400 parts quartz sand with a particle size of 40-60 μm, 3 parts polycarboxylate-based high-performance water-reducing agent, 0.2 parts calcium formate as an early-strength agent, 0.2 parts sodium gluconate as a retarder, and 180 parts water.

[0068] A method for preparing the above-mentioned mortar includes the following steps: Step 1: Measuring and mixing: Weigh PC42.5 silicate cement and fly ash according to a predetermined ratio, and premix them evenly to obtain cementitious component A; weigh 0.8-2mm steel slag and 40-60μm quartz sand according to a predetermined ratio and mix them evenly to obtain aggregate component B; weigh polycarboxylate-based high-performance water-reducing agent, calcium formate, sodium gluconate and half the total weight of water according to a predetermined ratio and mix them evenly to obtain admixture component C.

[0069] Step 2: Mixing: Start the small horizontal mixer and set the speed to 65 r / min. Then add aggregate component B and one-quarter of the total weight of water. Mix quickly for 10 seconds to wet the surface of the aggregate material. Then add cementitious component A and continue mixing for 15 seconds to fully coat the surface of the aggregate material. Then add admixture component C and one-quarter of the total weight of water and continue mixing for 30 seconds to obtain the mortar in this comparative example.

[0070] Step 3: Molding: The mixed material is fed into a 40*40*160 mm mortar mold to prepare mortar test blocks.

[0071] Step 4: Curing: Place the mortar test block and mortar mold into the curing kiln for curing. The curing temperature is controlled at 21℃ and the relative humidity is ≥90%.

[0072] The component ratios of the above embodiments and comparative examples are shown in Table 1 below: Table 1 Component Ratios of Embodiments and Comparative Examples The performance of the rapid-strength, early-strength repair mortars prepared in the above examples and comparative examples was tested. The setting time was tested according to GB / T1346-2011 "Standard Consistency Water Requirement, Setting Time and Soundness Test Methods for Cement", and the strength was tested according to GB / T17671-2021 "Test Methods for Strength of Cement Mortar (ISO Method)". The test results are shown in Table 2 below: Table 2 Test Results of Examples and Comparative Examples 1. Compared with Comparative Examples 1 and 2, the 1-hour compressive strength of Examples 1 and 2 is about 5 times that of Comparative Examples 1 and 2, and the early strength development rate is significantly accelerated.

[0073] The 1-day compressive strength of Examples 1 and 2 is increased by about 50% compared with Comparative Examples 1 and 2, which solves the problem of insufficient early strength of traditional admixture-free mortar.

[0074] The 30-minute fluidity of Examples 1 and 2 was higher than that of Comparative Examples 1 and 2, which avoided the problems of mortar viscosity and poor fluidity caused by the absence of admixtures and improved the operability of construction.

[0075] The final setting time of Examples 1 and 2 was only about 50% of that of Comparative Examples 1 and 2, indicating a significant acceleration in hardening speed. The initial setting time of Examples 1 and 2 was close to that of Comparative Examples 1 and 2, demonstrating that the retarder effectively avoided the risk of rapid setting caused by the accelerator, balancing construction operation time and early hardening efficiency.

[0076] Examples 1 and 2 achieved a 69.6%-75.4% rate of reaching the design strength within 12-24 hours, while Comparative Examples 1 and 2 did not have this capability, thus meeting the need for rapid reinforcement and repair and improving the efficiency of early strength achievement.

[0077] The 28-day strength of Examples 1 and 2 is comparable to that of Comparative Examples 1 and 2, indicating that the early strength improvement does not sacrifice the later strength stability.

[0078] 2. Compared with Comparative Example 3, the planned compressive strength of Example 1 is increased by about 34%, indicating a more sufficient reserve of basic strength. The 1-hour compressive strength and 1-day compressive strength of Example 1 are increased by 105% and 55% respectively compared with Comparative Example 3. The early strength of rapid-hardening sulfoaluminate cement solves the problem of early strength lag in single silicate cement.

[0079] Compared with Comparative Example 3, the proportion of Example 1 that reaches the design strength within 12-24 hours is increased by about 16%, which can complete the strength requirements of reinforcement and repair more quickly.

[0080] The 30-minute fluidity of Example 1 is lower than that of Comparative Example 3, which avoids the problems of aggregate segregation and loose structure caused by excessive fluidity of single silicate cement mortar, and the construction and molding quality is more stable.

[0081] Compared with Comparative Example 3, the initial setting time and final setting time of Example 1 were both shortened. The rapid-hardening sulfoaluminate cement accelerated the hydration and hardening process, making it more suitable for emergency repair scenarios.

[0082] The 28-day compressive strength of Example 1 was increased by about 31% compared with Comparative Example 3, indicating that the blending of rapid-hardening sulfoaluminate cement and silicate cement not only enhanced the early strength but also improved the later strength and durability.

[0083] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A rapid-strength, early-strength repair mortar, characterized in that, It includes the following components by weight: 40-60 parts rapid-hardening sulfoaluminate cement, 340-400 parts silicate cement, 1800 parts steel slag, 40 parts fly ash, 400 parts quartz sand, 1-7 parts water-reducing agent, 0.1-2.0 parts early-strength agent, 0.1-2.0 parts retarder, and 120-200 parts water.

2. The rapid-strength, early-strength repair mortar according to claim 1, characterized in that, It includes one or more of the following characteristics: (a) the rapid-hardening sulfoaluminate cement is 42.5 rapid-hardening sulfoaluminate cement; (b) the silicate cement is PC42.5 silicate cement; (c) the water is industrial tap water.

3. The rapid-strength, early-strength repair mortar according to claim 1, characterized in that, Includes one or more of the following characteristics: (a) steel slag particle size is 0.8-3 mm; (b) fly ash specific surface area ≥ 250 m². 2 / kg, 28d activity index ≥70%; (c) Quartz sand particle size is 40-70μm.

4. The rapid-strength, early-strength repair mortar according to claim 1, characterized in that, It includes one or more of the following characteristics: (a) the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent or a naphthalene-based high-efficiency water-reducing agent; (b) the early-strength agent is a calcium formate or a sodium sulfate / triethanolamine composite early-strength agent; (c) the retarder is a sodium gluconate or a citric acid / tartaric acid composite retarder.

5. A method for preparing a rapid-strength, early-strength repair mortar as described in any one of claims 1-4, characterized in that, Includes the following steps: Step Step 1: Measurement and Mixing: Weigh rapid-hardening sulfoaluminate cement, silicate cement, and fly ash according to the predetermined ratio, and premix them evenly to obtain cementitious component A; weigh steel slag and quartz sand according to the predetermined ratio and mix them evenly to obtain aggregate component B; weigh water-reducing agent, early-strength agent, retarder, and half the total weight of water according to the predetermined ratio and mix them evenly to obtain admixture component C; Step 2: Mixing: Add aggregate component B and one-quarter of the total weight of water, mix quickly, then add cementitious component A and continue mixing, then add admixture component C and one-quarter of the total weight of water and continue mixing to obtain rapid-strength repair mortar; Step 3: Molding: Send the mixed materials into mortar molds to prepare mortar test blocks; Step 4: Curing: Place the mortar test blocks and mortar molds into a curing kiln for curing.

6. The method for preparing the rapid-strength, early-strength repair mortar according to claim 5, characterized in that, The mixing in step two is carried out in a small horizontal mixer at a speed of 60-80 r / min.

7. The method for preparing the rapid-strength, early-strength repair mortar according to claim 6, characterized in that, In step two, after adding component B, quickly mix and stir for 10-15 seconds to wet the surface of the aggregate.

8. The method for preparing the rapid-strength, early-strength repair mortar according to claim 7, characterized in that, In step two, after adding component A, continue stirring for 15-20 seconds.

9. The method for preparing the rapid-strength, early-strength repair mortar according to claim 8, characterized in that, In step two, after adding component C, continue stirring for 25-30 seconds.

10. The method for preparing the rapid-strength, early-strength repair mortar according to claim 5, characterized in that, Includes one or more of the following characteristics: (a) In step three, the mixed material is fed into a 40*40*160 mm mortar mold to prepare mortar test blocks; (b) In step four, during curing, the temperature is controlled at 20±1℃ and the relative humidity is ≥90%.

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