Rapid repair mortar and preparation method and application thereof

Abstract

The invention belongs to the technical field of building materials, and particularly relates to rapid repair mortar as well as a preparation method and application thereof, raw materials and proportions of the rapid repair mortar are obtained through an optimization mechanism and efficient experimental design; the quick repair mortar is prepared by further compounding quick-hardening sulphoaluminate cement, superfine Portland cement, high-calcium fly ash, redispersible latex powder, basalt fibers, an accelerator, a polycarboxylic acid high-efficiency water reducing agent, a defoaming agent, standard sand and water, and the mortar slurry is excellent in early physical performance and can meet the requirement for quick repair of concrete pavements; good durability is achieved, and the repairing service life can be prolonged.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a rapid repair mortar, its preparation method, and its application. Background Technology

[0002] Concrete pavements are prone to potholes, cracks, exposed aggregate, and edge spalling due to long-term exposure to traffic loads and environmental erosion (such as freeze-thaw cycles, salt corrosion, and alternating wet and dry conditions). If these defects are not repaired promptly, they will exacerbate pavement damage, affect traffic safety, and increase subsequent maintenance costs.

[0003] Currently, concrete pavement repair materials on the market are mainly divided into four categories: inorganic repair materials, organic repair materials, organic-inorganic composite repair materials, and self-healing materials, but all of them have obvious defects: Inorganic repair materials: based on ordinary silicate cement or special cement (such as sulfoaluminate cement and magnesium phosphate cement), although the cost is low, they generally have problems such as slow early strength development, poor interfacial adhesion, high drying shrinkage and easy cracking, which make it difficult to meet the emergency repair needs of "rapid reopening". Organic repair materials, such as epoxy resin and acrylic resin, have excellent bonding properties, but they are expensive, have poor weather resistance and are prone to aging, and are not suitable for large-scale repair projects. Organic-inorganic composite repair materials: Although they combine the advantages of both types of materials, the air-entraining effect of polymers (such as latex powder) will increase the porosity of mortar, reduce mechanical strength and durability, and large amounts of polymers are prone to agglomeration, which will hinder the cement hydration process. Self-healing materials, such as microbial-induced calcium carbonate deposition materials, are still in the theoretical research and development stage. They have long repair cycles and unstable effects, and cannot meet the time requirements for rapid road repair.

[0004] Therefore, developing a rapid repair mortar with excellent early physical properties, good durability, and controllable cost has significant engineering value. Summary of the Invention

[0005] Based on the problems in the background technology, the present invention provides a rapid repair mortar, its preparation method and application, which is especially suitable for road emergency repair projects with high requirements for early physical properties and durability, such as the repair of potholes, cracks and edge peeling of concrete pavements such as highways, municipal roads and airport runways.

[0006] The technical solution of the present invention is as follows: This invention provides a rapid repair mortar, wherein the raw material components and proportions of the rapid repair mortar, by mass ratio, are as follows: Rapid-hardening sulfoaluminate cement: Ultrafine silicate cement: High-calcium fly ash: Redispersible latex powder: Basalt fiber: Accelerator: Polycarboxylate superplasticizer: Defoamer: Sand: Water = 60-70: 30-40: 40-50: 2.5-3.3: 0.30-0.40: 1.5-2.1: 1.5-2.1: 0.12-0.18: 150-170: 22-28.

[0007] Furthermore, the ratio of rapid-hardening sulfoaluminate cement: ultrafine silicate cement: high-calcium fly ash: redispersible latex powder: basalt fiber: quick-setting agent: polycarboxylate superplasticizer: defoamer: standard sand: water = 65:35:45:2.9:0.35:1.8:1.8:0.15:160:25.

[0008] The mass fractions of CaO, SiO2, Al2O3, and SO3 in the rapid-hardening sulfoaluminate cement are 43.0%-48.0%, 9.5%-12.0%, 18.0%-22.0%, and 13.5%-16.5%, respectively. The flexural strengths at 4 hours, 1 day, and 28 days are 4.0-4.4, 5.1-5.5, and 7.5-7.9 MPa, respectively, and the compressive strengths at 4 hours, 1 day, and 28 days are 24.8-25.3, 31.5-32.3, and 57.3-58.5 MPa, respectively.

[0009] The mass fractions of CaO, SiO2, Al2O3, Fe2O3, and MgO in ultrafine silicate cement are 60.0%-66.0%, 19.0%-22.0%, 3.5%-4.7%, 2.0%-2.5%, and 3.8%-3.95%, respectively. The flexural strengths at 3 days and 28 days are 6.2-6.7 and 9.0-9.4 MPa, respectively, and the flexural strengths at 3 days and 28 days are 48.4-49.8 and 72.6-73.7 MPa, respectively.

[0010] The loss on ignition of high-calcium fly ash is 1.63-8.17, and the mass fractions of CaO, SiO2, Al2O3 and Fe2O3 are 18%-20%, 45%-48%, 21%-25% and 3.2%-3.4%, respectively.

[0011] In addition, the redispersible latex powder has an average particle size of 150 μm and its components include copolymers of ethylene and vinyl acetate.

[0012] The monofilament diameter of basalt fiber is 7-15 μm, and the density is 2.63-2.65 g / cm³. 3 Its elastic modulus is 91-110 GPa, and its tensile strength is 3000-4800 MPa.

[0013] Furthermore, the defoamer is polyether type, and the sand is medium sand with a particle size of 0.5-1.0mm.

[0014] The present invention also provides a method for preparing the aforementioned rapid repair mortar, comprising the following steps: (1) Pre-disperse basalt fibers and sieve high-calcium fly ash; (2) Quick-hardening sulfoaluminate cement, ultrafine silicate cement, sieved high-calcium fly ash, redispersible latex powder, dispersed basalt fiber, polycarboxylate superplasticizer, defoamer, and quick-setting agent are mixed in proportion. (3) Add the pre-set amount of water and continue stirring; (4) Add sand and continue stirring to obtain mortar.

[0015] The stirring in step (2) is at a speed of 60-65 r / min for 30 s; the stirring in step (3) is at a speed of 125 r / min for 30 s; the stirring in step (4) is at a speed of 125 r / min for 240-260 s.

[0016] Furthermore, the stirring in step (2) is performed at a speed of 62 r / min for 30 s.

[0017] The present invention also provides an application of the aforementioned rapid repair mortar in the repair of concrete pavements.

[0018] Furthermore, the construction steps of the application include: After removing loose concrete and dust from the surface of the affected area, pour mortar into the affected area, compact it with a vibrating table, smooth the surface with a trowel, and cover it with plastic wrap for outdoor curing.

[0019] The application scenarios include the repair of potholes, cracks, and edge peeling defects on the ground of highways, municipal roads, airport runways, railway stations, ports, and industrial plants.

[0020] The present invention also provides a method for optimizing the performance of the aforementioned rapid repair mortar, comprising: (1) Taking the composite cementitious system of rapid hardening sulfoaluminate cement and ultrafine silicate cement as the core, setting time, mechanical strength at 4 hours and 1 day as indicators, the water-cement ratio and sand-cement ratio were optimized through orthogonal experiments and single-factor experiments, and the mix proportion based on rapid hardening sulfoaluminate cement, ultrafine silicate cement, quick-setting agent, water, sand and polycarboxylate high-efficiency water-reducing agent was determined. (2) Based on the benchmark mix ratio and the amount of defoamer added, the dosage of redispersible latex powder was optimized by single-factor experiments; based on the optimal dosage of redispersible latex powder, the dosage of basalt fiber was optimized by single-factor experiments to obtain VAE-BF type mortar. (3) Based on VAE-BF type mortar, by separately doping high-calcium fly ash, nano silica, or compound doping high-calcium fly ash and nano silica, and using initial setting time, final setting time, initial fluidity, flexural strength, compressive strength, interfacial flexural strength, interfacial tensile bond strength, and drying shrinkage rate as indicators, orthogonal experiments were conducted to obtain the raw material composition and proportion of rapid repair mortar.

[0021] Beneficial effects This invention, through optimized mechanism and efficient experimental design, obtains the raw materials and their proportions for rapid repair mortar; then, it combines rapid-hardening sulfoaluminate cement, ultrafine silicate cement, high-calcium fly ash, redispersible latex powder, basalt fiber, accelerator, polycarboxylate superplasticizer, defoamer, sand, and water to prepare rapid repair mortar. This mortar exhibits excellent early physical properties, meeting the requirements for rapid repair of concrete pavements; it also possesses good durability, extending the repair life. Attached Figure Description

[0022] Figure 1 For the load-bearing capacity test of repair location 1.

[0023] Figure 2 Durability test for repair location 2. Detailed Implementation

[0024] The following examples are intended to illustrate the present invention, and not to further limit the invention.

[0025] This invention, through optimized mechanisms and efficient experimental design, aims to obtain a rapid repair mortar that meets the requirements for longer service life. The process includes: (1) Taking the composite cementitious system of rapid hardening sulfoaluminate cement and ultrafine silicate cement as the core, the setting time, mechanical strength at 4 hours and 1 day as indicators, the water-cement ratio and sand-cement ratio are optimized, and the mix proportion based on rapid hardening sulfoaluminate cement, ultrafine silicate cement, quick-setting agent, water, sand and polycarboxylate high-efficiency water-reducing agent is determined. (2) Based on the benchmark mix ratio and the amount of defoamer added, the dosage of redispersible latex powder was optimized; based on the optimal dosage of redispersible latex powder, the dosage of basalt fiber was optimized to obtain VAE-BF type mortar. (3) Based on VAE-BF type mortar, by separately doping high-calcium fly ash, nano silica, or compound doping high-calcium fly ash and nano silica, and using initial setting time, final setting time, initial fluidity, flexural strength, compressive strength, interfacial flexural strength, interfacial tensile bond strength, and drying shrinkage rate as indicators, orthogonal experiments were conducted to obtain the raw material composition and proportion of rapid repair mortar.

[0026] Through the above process, the present invention obtains a rapid repair mortar. The raw material components and proportions of the rapid repair mortar, by mass ratio, are as follows: Rapid-hardening sulfoaluminate cement: Ultrafine silicate cement: High-calcium fly ash: Redispersible latex powder: Basalt fiber: Accelerator: Polycarboxylate superplasticizer: Defoamer: Sand: Water = 65:35:45:2.9:0.35:1.8:1.8:0.15:160:25.

[0027] The rapid-hardening sulfoaluminate cement contains 45.64% CaO, 10.87% SiO2, 20.15% Al2O3, and 15.04% SO3 by mass, respectively. It also includes Fe2O3 (3.12%), MgO (2.48%), Na2O (0.21%), K2O (0.38%), MnO (0.28%), SrO (0.11%), and P2O5 (0.49%). Its flexural strength at 4 hours, 1 day, and 28 days is 4.4, 5.5, and 7.9 MPa, respectively, and its compressive strength at 4 hours, 1 day, and 28 days is 25.3, 32.3, and 58.5 MPa, respectively.

[0028] The mass fractions of CaO, SiO2, Al2O3, Fe2O3, and MgO in the ultrafine silicate cement are 63.21%, 20.60%, 4.11%, 2.27%, and 3.91%, respectively. It also contains Na2O (0.09%), K2O (0.39%), and SO3 (1.94%). The flexural strengths at 3 days and 28 days are 6.7 and 9.4 MPa, respectively, and the flexural strengths at 3 days and 28 days are 49.8 and 73.7 MPa, respectively.

[0029] The loss on ignition of high-calcium fly ash is 1.63-8.17, and the mass fractions of CaO, SiO2, Al2O3, and Fe2O3 are 18%, 48%, 21%, and 3.3%, respectively. It also contains MgO (1.6%), Na2O (2.1%), and SO3 (1.5%).

[0030] In addition, the redispersible latex powder has an average particle size of 150 μm and its components include copolymers of ethylene and vinyl acetate.

[0031] The monofilament diameter of basalt fiber is 7-15 μm, and the density is 2.63-2.65 g / cm³. 3 Its elastic modulus is 91-110 GPa, and its tensile strength is 3000-4800 MPa.

[0032] The quick-setting agent is model CLZ, and the polycarboxylate superplasticizer has a water reduction rate of 45%.

[0033] The defoamer is polyether type, and the sand is medium sand with a fineness modulus of 2.55 and a particle size of 0.5-1.0 mm.

[0034] Example 2 Based on Example 1, this example provides a method for preparing rapid repair mortar, including the following steps: (1) Pre-disperse basalt fibers and pass high-calcium fly ash through a 325-mesh sieve; (2) Add rapid hardening sulfoaluminate cement, ultrafine silicate cement, sieved high-calcium fly ash, redispersible latex powder, dispersed basalt fiber, polycarboxylate superplasticizer, defoamer, and quick-setting agent to the cement mortar mixer in proportion and stir at 62r / min for 30s. (3) Add the preset amount of water, increase the speed to 125 r / min and continue stirring for 30 s; (4) Add standard sand and continue stirring at 125 r / min for 240 s to form a uniform mortar without lumps. If dry material agglomerates, the stirring time can be extended by 10-20 s to obtain the mortar.

[0035] Example 3 Based on Example 2, in the process of preparing the mortar for rapid repair, in order to achieve the pre-dispersion of basalt fibers and efficient mixing with other dry powder materials, while taking into account the feasibility, convenience and reduction of material loss in actual operation, firstly, a metal screen with an aperture of 0.5-1mm is selected as the dispersion tool. Screen dispersion can break up fiber agglomerates through physical sieving, and the tool is easy to obtain and has a low operating threshold, making it suitable for rapid on-site processing.

[0036] Next, weigh the basalt fiber according to the formula requirements, and spread the fiber evenly on the sieve, controlling the thickness to 5-10mm (avoiding excessive thickness which would lead to incomplete sieving). Use a wooden scraper to slowly scrape along the surface of the sieve, allowing the fiber to pass through and fall into a clean plastic container below. If a small amount of agglomerates cannot pass through the sieve, gently rub them with your fingers until they disperse before sieving, ensuring that the dispersed fiber is free of obvious clumps. Operating in batches avoids uneven dispersion caused by a single accumulation of fiber, and also reduces fiber loss due to wind or operational errors during the dispersion process.

[0037] Then, following the principle of "large particles first, then small particles; inert components first, then active components," the dispersed basalt fibers were mixed with other dry powder materials in a specific ratio. The details are as follows: Rapid-hardening sulfoaluminate cement and ultrafine silicate cement are added to a cement mortar mixer and pre-mixed at 62 r / min for 15 seconds to form a uniform skeleton of coarse particles, providing a "carrier" for subsequent fiber dispersion. The pre-dispersed basalt fiber and sieved high-calcium fly ash are slowly added to the mixer and stirred at 62 r / min for 15 seconds. The flow of cement particles is used to drive the fiber to be evenly distributed, avoiding local agglomeration caused by direct contact between the fiber and active components (such as redispersible latex powder). Add redispersible latex powder, polycarboxylate superplasticizer, defoamer, and quick-setting agent, and stir at 62 rpm for 30 seconds to complete the mixing of all dry powder materials. The mixture is considered qualified when the powder material as a whole appears uniformly grayish-white and has no obvious fiber bundles or color patches.

[0038] Example 4 The mortar prepared according to Example 3 was applied to the repair of concrete pavement. The construction steps included: Use a wire brush to remove loose concrete and dust from the surface of the affected area. After blowing away any remaining impurities with a blower, pour the mortar into the affected area, compact it with a vibrating table, smooth the surface with a trowel, cover it with plastic wrap, and cure it outdoors in a natural environment (20±3℃, relative humidity 60±5%) for 4 hours.

[0039] Experimental Analysis 1. Comparative analysis with technical indicators Based on the current national standards JT / T1211.1-2018-CRRM-III "Rapid Repair Materials for Cement Concrete in Highway Engineering - Part 1: Cement-Based Repair Materials" and JC / T2381-2016-QNS "Repair Mortar", and combined with the characteristics of actual repair projects, corresponding technical indicators for rapid repair mortar are proposed.

[0040] The early physical properties and technical indicators of the mortar in Example 2 (denoted as VAE-BF-CFA type mortar) are compared, and the results are shown in Table 1.

[0041] Table 1. Evaluation of early physical properties of mortar in Example 2 Table 1 shows that, except for the 4-hour compressive strength, the early physical properties of the mortar in Example 2 all meet the technical requirements. At the same time, it has excellent early interfacial bonding performance, flexural strength and expansion effect.

[0042] In addition, the mortar in Example 2 has a longer initial setting time (28 minutes) and a shorter final setting time (38 minutes). This allows the mortar to ensure rapid road reopening while also providing a longer workable period, which is highly suitable for actual repair conditions. Therefore, overall, the mortar provided by this invention has excellent early physical properties.

[0043] 2. Practical Engineering Application and Evaluation of Repair Effects The mortar obtained in Example 3 was applied to the actual repair work of two concrete road defects using the simple operation described in Example 4. Repair location 1 was located at the main entrance of an industrial park in Daiyue District, Tai'an City, with an average daily traffic volume greater than 29 pcu / h. Repair location 2 was located at the main entrance of a company in Taishan District, Tai'an City, with an average daily traffic volume greater than 37 pcu / h.

[0044] Engineering Application 1: Repair Location 1 is a road surface with uneven potholes and a large damaged area. This location is mainly used to test the mechanical bearing capacity of the repair mortar under actual load. Test Vehicle: Single-row flatbed light truck (HFC1041P52K3C2V), with a total mass of 4.495 tons, a front wheelbase of 1560mm, and a rear wheelbase of 1530mm.

[0045] Four hours after the repair mortar hardened, vehicle loads were applied to the boundary of the repair area (the interface between the mortar and the old concrete) and the center of the repair area. The repair area was then observed for any damage. Finally, the mortar was allowed to harden for another 28 days, and the repair area was observed again for any damage. The experimental results are as follows: Figure 1 As shown.

[0046] according to Figure 1 As shown, 4 hours after repair, there were no obvious cracks or damage in the central area of ​​the repaired area, and at the two boundary locations of the repaired area, the old concrete and the repair mortar were tightly bonded without obvious separation. 28 days after repair, there was no obvious wear or cracks on the surface of the repaired area, and no obvious separation at the boundary locations of the repaired area. This indicates that the rapid repair mortar of the present invention has good early load-bearing performance.

[0047] Application 2: Repair location 2 involves edge and corner detachment, with a relatively small damaged area. Repairing this location primarily tests the actual durability of the repair mortar. Therefore, the appearance of the repaired area was observed after the mortar was placed in an actual engineering environment for 4 hours, 28 days, 3 months, 6 months, and 9 months. The results are as follows... Figure 2 As shown.

[0048] from Figure 2 It was found that after 4 hours, 28 days, and 3 months, the repaired area showed no obvious cracks or peeling, and the interface between the repair mortar and the old concrete showed good adhesion with no significant separation. After 6 months, the repaired area still showed no cracks, and the interface showed good adhesion with no significant separation, but localized wear appeared at the center of the repaired area. After 9 months, cracks appeared on the repaired area, and the edges showed signs of peeling. The repaired area was also completely worn down, becoming smooth. This indicates that within 6 months of repair, the actual durability of the repair mortar is good. After 6 months, the actual durability of the mortar is poor.

[0049] In summary, this invention, through optimized mechanism and efficient experimental design, obtains the raw materials and their proportions for rapid repair mortar; then, it combines rapid-hardening sulfoaluminate cement, ultrafine silicate cement, high-calcium fly ash, redispersible latex powder, basalt fiber, accelerator, polycarboxylate superplasticizer, defoamer, standard sand, and water to prepare rapid repair mortar. This mortar exhibits excellent early physical properties, meeting the requirements for rapid repair of concrete pavements; it also possesses good durability, extending the repair life.

Claims

1. A rapid repair mortar, characterized in that, The raw material components and proportions of the rapid repair mortar, by mass ratio, are as follows: Rapid-hardening sulfoaluminate cement: Ultrafine silicate cement: High-calcium fly ash: Redispersible latex powder: Basalt fiber: Accelerator: Polycarboxylate superplasticizer: Defoamer: Sand: Water = 60-70: 30-40: 40-50: 2.5-3.3: 0.30-0.40: 1.5-2.1: 1.5-2.1: 0.12-0.18: 150-170: 22-28.

2. The rapid repair mortar according to claim 1, characterized in that, Rapid-hardening sulfoaluminate cement: Ultrafine silicate cement: High-calcium fly ash: Redispersible latex powder: Basalt fiber: Accelerator: Polycarboxylate superplasticizer: Defoamer: Standard sand: Water = 65:35:45:2.9:0.35:1.8:1.8:0.15:160:

25.

3. The rapid repair mortar according to claim 1, characterized in that, The defoamer is polyether type; the sand is medium sand with a particle size of 0.5-1.0 mm.

4. A method for preparing rapid repair mortar as described in claim 1, characterized in that, Includes the following steps: (1) Pre-disperse basalt fibers and sieve high-calcium fly ash; (2) Quick-hardening sulfoaluminate cement, ultrafine silicate cement, sieved high-calcium fly ash, redispersible latex powder, dispersed basalt fiber, polycarboxylate superplasticizer, defoamer, and quick-setting agent are mixed in proportion. (3) Add the pre-set amount of water and continue stirring; (4) Add sand and continue stirring to obtain mortar.

5. The method for preparing rapid repair mortar according to claim 4, characterized in that, The stirring in step (2) is at a speed of 60-65 r / min for 30 s; the stirring in step (3) is at a speed of 125 r / min for 30 s; the stirring in step (4) is at a speed of 125 r / min for 240-260 s.

6. The method for preparing rapid repair mortar according to claim 5, characterized in that, The stirring in step (2) is performed at a speed of 62 r / min for 30 s.

7. The application of the rapid repair mortar as described in claim 1 in the repair of concrete pavement.

8. The application according to claim 7, characterized in that, The construction steps of the application include: After removing loose concrete and dust from the surface of the affected area, pour mortar into the affected area, compact it with a vibrating table, smooth the surface with a trowel, and cover it with plastic wrap for outdoor curing.

9. The application according to claim 7, characterized in that, The application scenarios include the repair of potholes, cracks, and edge peeling defects on the ground of highways, municipal roads, airport runways, railway stations, ports, and industrial plants.

10. A method for optimizing the performance of the rapid repair mortar as described in claim 1 or the rapid repair mortar obtained by the preparation method as described in claim 4, characterized in that, include: (1) Taking the composite cementitious system of rapid hardening sulfoaluminate cement and ultrafine silicate cement as the core, the setting time, mechanical strength at 4 hours and 1 day as indicators, the water-cement ratio and sand-cement ratio are optimized, and the mix proportion based on rapid hardening sulfoaluminate cement, ultrafine silicate cement, quick-setting agent, water, sand and polycarboxylate high-efficiency water-reducing agent is determined. (2) Based on the benchmark mix ratio and the amount of defoamer added, the dosage of redispersible latex powder was optimized; based on the optimal dosage of redispersible latex powder, the dosage of basalt fiber was optimized to obtain VAE-BF type mortar. (3) Based on VAE-BF type mortar, by separately doping high-calcium fly ash, nano silica, or compound doping high-calcium fly ash and nano silica, and using initial setting time, final setting time, initial fluidity, flexural strength, compressive strength, interfacial flexural strength, interfacial tensile bond strength, and drying shrinkage rate as indicators, orthogonal experiments were conducted to obtain the raw material composition and proportion of rapid repair mortar.

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