A pressurized compacting repair mortar and its use

Abstract

The application discloses a kind of pressurized dense repair mortar and its application, the pressurized dense repair mortar includes the following raw materials: cementing material, its admixture amount is 25wt%~30wt% of repair mortar;Fine aggregate, its admixture amount is 65wt%~68wt% of repair mortar;Active excitation component, it is composed of sodium silicate, gypsum, admixture amount is 4.4wt%~6.5wt% of repair mortar;Tackifying component, it is composed of cellulose ether, amide polymer compound, admixture amount is 0.4wt%~0.6wt% of repair mortar;Water reducing agent, its admixture amount is 0.5wt%~1wt% of cementing material;Water, its admixture amount is 17wt%~20wt% of cementing material;Wherein, water cement ratio is 0.17~0.2, cement bone ratio is 0.37~0.46.The repair mortar has dry hardness, plastic working performance, small shrinkage, high early strength, not easy to crack, good waterproof effect, high bonding strength with repaired concrete component, color consistency and the like advantages.

Description

Technical Field

[0001] This invention belongs to the field of concrete repair materials, and relates to a pressure-compacting repair mortar and its application. Background Technology

[0002] Commonly available repair mortars include polymer repair mortar and epoxy repair mortar. Repair mortars generally have good fluidity and are used to repair defects on concrete surfaces by brushing. However, they generally have the following problems: (1) They have a large shrinkage rate and are prone to secondary cracking in the later stage; (2) They have certain requirements for the construction environment. In environments with strong ultraviolet rays, high temperature and high humidity, the weather resistance of the products is poor, and the repair mortar is prone to yellowing or even decomposition and failure; (3) They widely use special fast-hardening cements such as sulfoaluminate cement, which are inconsistent with the color of the building being repaired, which can easily cause color difference and affect the aesthetics; (4) When repairing vertical surfaces, top surfaces and some narrow spaces such as bridge piers and abutments, the mortar is prone to flow, slip or light slurry floating due to gravity, which makes it difficult to control the thickness of the repaired part, and the repair material is uneven, which cannot achieve the strength and bearing capacity required by the design. Summary of the Invention

[0003] To address the above problems, this invention provides a pressurized compaction repair mortar and its application. This repair mortar has advantages such as dry hardness, non-flow, low shrinkage, high early strength, resistance to cracking, good waterproofing, high bonding strength with the repaired concrete component, and consistent color.

[0004] The technical solution provided by this invention is as follows:

[0005] In a first aspect, the present invention provides a pressurized compaction repair mortar, comprising the following raw materials:

[0006] Cementitious materials, the dosage of which is 25wt% to 30wt% of the repair mortar;

[0007] Fine aggregate, the dosage of which is 65wt% to 68wt% of the repair mortar;

[0008] The active activating component, composed of sodium silicate and gypsum, is added at a dosage of 4.4 wt% to 6.5 wt% of the repair mortar.

[0009] The thickening component, composed of cellulose ethers and amide polymers, is added at a dosage of 0.4 wt% to 0.6 wt% of the repair mortar.

[0010] Water-reducing agent, the dosage of which is 0.5wt% to 1wt% of cementitious material;

[0011] Water, the amount of which is 17wt% to 20wt% of the cementitious material;

[0012] The water-to-gel ratio is 0.17–0.2, and the glue-to-bond ratio is 0.37–0.46.

[0013] In some embodiments of the present invention, the pressurized compacted repair mortar is consistent with the fine aggregate type and gradation, and cementitious material composition of the concrete component being repaired. Consistent cementitious material composition means that the types of components and the proportions between them are identical.

[0014] In some embodiments of the present invention, the water-to-glue ratio is 0.17 to 0.18, and the glue-to-bond ratio is 0.46.

[0015] In some embodiments of the present invention, the amount of cellulose ether is 0.2wt% to 0.4wt% of the repair mortar; the weight average molecular weight of the amide polymer compound is 6 million to 10 million, and the amount is 0.2wt% to 0.3wt% of the repair mortar; the amount of sodium silicate is 3wt% to 5wt% of the repair mortar; and the amount of gypsum is 0.5wt% to 1.5wt% of the repair mortar.

[0016] In some embodiments of the present invention, the amide polymer is polyacrylamide or sodium polyacrylate; the cellulose ether is one or more of carboxymethyl cellulose and hydroxypropyl methyl cellulose; the sodium silicate has a modulus of one or more of 2.0 to 2.4; and the gypsum is 120 mesh to 150 mesh.

[0017] Secondly, the present invention provides a method for repairing concrete interfaces, comprising:

[0018] Prepare the above-mentioned pressurized and compacted repair mortar;

[0019] Make the pressurized and compacted repair mortar come into contact with the interface being repaired;

[0020] Compact the pressure-dense repair mortar and allow it to cure naturally.

[0021] In some embodiments of the present invention, the interface to be repaired is located in one or more of the following: a vertical surface, a top surface, and a confined space.

[0022] In some embodiments of the present invention, preparing the above-mentioned pressurized and compacted repair mortar includes:

[0023] The cementitious materials and fine aggregates are pre-dry mixed to obtain solid materials;

[0024] Add the water-reducing agent and half the water to the solid material and mechanically stir to obtain a moist mixture;

[0025] Add the modifier and the remaining water to the moistened mixture and continue stirring for at least 120 seconds.

[0026] In some embodiments of the present invention, bringing the pressurized compacted repair mortar into contact with the interface to be repaired includes:

[0027] ( i Place the repair mortar in a handheld press and extrude it onto the surface to be repaired; or,

[0028] ( ii Squeeze the repair mortar into a ball and press it onto the surface to be repaired.

[0029] In some embodiments of the present invention, the compaction strength of the pressurized and dense repair mortar is 10 to 50 MPa.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The repair mortar of the present invention has dry hardening and plastic working properties, making it very suitable for repairing vertical surfaces, top surfaces, narrow spaces, and areas where formwork cannot be erected.

[0032] 2. The type of fine aggregate and the composition of the cementitious material in the repair mortar of the present invention are consistent with those of the concrete component being repaired. This not only ensures that the color of the repair layer is consistent with that of the concrete component being repaired, but also allows for the use of locally sourced materials, such as cementitious materials and fine aggregates, to prepare the repair mortar of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0034] For simplicity, this document only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range. Similarly, any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can be used as its own lower or upper limit, combined with any other point or individual value, or combined with other lower or upper limits to form an unspecified range.

[0035] It should be noted that, in the description herein, unless otherwise stated, "above" and "below" include the stated number, and "multiple" in "one or more" means two or more. Relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0036] In the description of this specification, the references to terms such as "any embodiment / mode," "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0037] The above description of the invention is not intended to describe every disclosed embodiment or implementation of the invention. Exemplary embodiments are described in more detail below. These embodiments can be used in various combinations. In each example, the listing is merely representative and should not be construed as exhaustive.

[0038] Repair mortar

[0039] As described in the background section, existing repair mortars have high flowability and are not suitable for repairing vertical or overhead surfaces, as well as confined spaces. To solve these problems, this invention provides a pressurized and compacted repair mortar, comprising the following raw materials:

[0040] Cementitious materials, the dosage of which is 25wt% to 30wt% of the repair mortar;

[0041] Fine aggregate, the dosage of which is 65wt% to 68wt% of the repair mortar;

[0042] The active activating component, composed of sodium silicate and gypsum, is added at a dosage of 4.4 wt% to 6.5 wt% of the repair mortar.

[0043] The thickening component, composed of cellulose ethers and amide polymers, is added at a dosage of 0.4 wt% to 0.6 wt% of the repair mortar.

[0044] Water-reducing agent, the dosage of which is 0.5wt% to 1wt% of cementitious material;

[0045] Water, the amount of which is 17wt% to 20wt% of the cementitious material;

[0046] The water-to-gel ratio is 0.17–0.2, and the glue-to-bond ratio is 0.37–0.46.

[0047] The repair mortar of this invention uses a cementitious material with a small amount of cementitious material and a large amount of fine aggregate. The cement-aggregate ratio of this repair mortar (0.46-0.36) is much lower than that of conventional repair mortar (1.5-0.6). The large amount of fine aggregate plays a role in restraining deformation. Therefore, the shrinkage deformation of the repair mortar during the hardening process is small, and it is not easy to crack. In addition, the water-cement ratio of the repair mortar of this invention is low. Compared with conventional repair mortar, it has poor fluidity, which is reflected in that it can be formed into a ball when squeezed by hand. There is less water evaporation, the setting speed is faster, and it is less prone to cracking and peeling.

[0048] In some embodiments of the present invention, the water-cement ratio is 0.17 to 0.18, the glue-aggregate ratio is 0.46, the strength of the repair layer is higher, and the bonding strength with the repaired concrete component is higher.

[0049] In the pressurized compaction repair mortar of this invention, the cementitious material accounts for 25wt% to 30wt% of the repair mortar. Compared with conventional repair mortar, the cementitious material is greatly reduced. Therefore, the repair mortar has a low shrinkage rate after drying and hardening and is not prone to cracking.

[0050] In some embodiments of the present invention, the type of fine aggregate and the composition of the cementitious material in the pressurized compacted repair mortar are consistent with those in the concrete component being repaired, ensuring that the color of the pressurized compacted repair mortar remains consistent with that of the concrete component being repaired. In some embodiments of the present invention, the cementitious material is composed of cement, mineral powder, and fly ash. The cementitious material system of commonly repaired concrete components generally consists of ordinary Portland cement, fly ash, and mineral powder. The glassy structure of mineral admixtures such as mineral powder is mainly composed of calcium, silicon, and small amounts of aluminum and magnesium. Under alkaline conditions, it can undergo decomposition, dissolving different ions to further promote the hydration process.

[0051] The water content in the pressurized compaction repair mortar of this invention is 17wt% to 20wt% of the cementitious material. Compared with conventional repair mortar, it has less water and a faster setting speed, thus forming a dry and hard material that can be clumped together by hand.

[0052] The water-cement ratio of the pressurized compaction repair mortar of this invention is 0.17–0.2. Compared with conventional repair mortars, the lower water-cement ratio can improve the flexural and compressive strength of the repair layer. When the water-cement ratio is too low, the shrinkage rate of the repair layer after drying and hardening is high, making it prone to drying shrinkage cracks and resulting in poor waterproofing; when the water-cement ratio is too high, the strength of the repair layer is low. Note: The water-cement ratio refers to the mass ratio of water to the total mass of the cementitious material.

[0053] Conventional quick-setting cement-based repair mortars or polymer repair mortars generally have a binder-to-aggregate ratio higher than 1. The binder-to-aggregate ratio of the pressure-compacting repair mortar of this invention is 0.37–0.46, with fine aggregate accounting for 65 wt%–68 wt% of the mortar. This is to use the aggregate as the main component to constrain deformation. When the binder-to-aggregate ratio is too low, the repair layer will have insufficient flexural strength due to the excessive fine aggregate content; when the binder-to-aggregate ratio is too high, the repair layer will have excessive drying shrinkage due to the high cementitious material content, making it prone to drying shrinkage cracks. Note: The binder-to-aggregate ratio refers to the ratio of the total mass of cementitious materials to the mass of fine aggregate. In the embodiments of this invention, river sand is used as the fine aggregate. Those skilled in the art can replace it with manufactured sand or recycled sand according to the availability of materials, as long as the type and gradation of the aggregate used in the raw materials of the concrete being repaired remain consistent.

[0054] The water-reducing agent in the pressurized compaction repair mortar of this invention is 0.5wt% to 1wt% of the cementitious material. This content can ensure that the repair mortar has a dry and hard state when it leaves the machine, and that the aggregate is coated with the adhesive.

[0055] The active activating component of the pressurized compaction repair mortar of this invention consists of sodium silicate and gypsum, with an admixture dosage of 4.4wt% to 6.5wt% of the repair mortar. Sodium silicate and gypsum synergistically activate the cementitious materials of the repair material and the concrete component being repaired. Under the action of sodium silicate and gypsum, mineral admixtures such as cement, mineral powder, and fly ash can maximize their potential activity. Sodium silicate promotes the hydration process, generating a large number of network-like CSH crystals and a small amount of AFt crystals, forming a dense crystalline gel structure. This significantly improves the early mechanical strength and water resistance of the repair material, ensuring that the repair mortar has higher mechanical properties than the concrete structure being repaired, thus avoiding the creation of weak areas.

[0056] Gypsum is poorly soluble in water, and when added alone to repair mortar with a low water-cement ratio, the reaction may be insufficient, failing to achieve the expected retarding effect and significantly shortening the worker's construction time. Sodium silicate (Na2SiO3) and gypsum (CaSO4·2H2O) undergo a chemical reaction to produce sodium sulfate (Na2SO4) and calcium silicate (CaSiO3). The reaction equation is as follows:

[0057] Na2SiO3+CaSO4·2H2O→Na2SO4+CaSiO3+2H2O

[0058] The product, sodium sulfate, has a certain degree of solubility and can dissociate into sodium ions (Na+) in water. + ) and sulfate ions (SO4) 2- Sulfate ions can promote the secondary hydration of mineral admixtures such as cement and mineral powder, activate their activity, and improve early strength. Furthermore, the products generated after chemical reaction with cement and mineral powder have a certain degree of viscosity, which further enhances the bonding performance.

[0059] In other words, sodium silicate acts as an alkaline activator, and the silicon in sodium silicate combines with calcium ions in cement to form CSH gel-like products. As calcium ions are continuously consumed, the vitreous body of the mineral powder is forced to continue decomposing and consuming the alkali in the system. Adding an appropriate amount of gypsum for regulation can promote the formation of ettringite. This alkaline activation reaction occurs simultaneously within the repair mortar and at the interface of the repaired concrete component. The reaction between the repaired concrete component and the repair mortar, and the hydration products generated at the interface, act as a binder, enhancing the overall integrity.

[0060] The thickening component of this invention consists of cellulose ethers and amide polymers, with an admixture dosage of 0.4wt% to 0.6wt% of the repair mortar. It can increase the mortar consistency and improve interfacial bonding strength. Cellulose ethers and amide polymers are high molecules with good compatibility with cement-based materials. They will deposit or agglomerate on the surface of hydrated cement and aggregates, forming a thin film. This film will form an interpenetrating network structure with the cement hydration products. Because the admixture dosage is relatively low, this flexible network structure mainly affects the flowability of the repair mortar, has a water-retaining effect, and increases the consistency of the freshly mixed repair mortar. The freshly mixed repair mortar does not have self-flowing characteristics; it is a loose paste-coated sand particle with a slump of less than 10mm, and it can be formed into a ball when squeezed by hand.

[0061] In some embodiments of the present invention, the cellulose ether is added at 0.2 wt% to 0.4 wt% of the repair mortar; the amide polymer has a weight-average molecular weight of 6 million to 10 million and is added at 0.2 wt% to 0.3 wt% of the repair mortar; the sodium silicate is added at 3 wt% to 5 wt% of the repair mortar; and the gypsum is added at 0.5 wt% to 1.5 wt% of the repair mortar. The amide polymer is polyacrylamide or sodium polyacrylate; the cellulose ether is one or more of carboxymethyl cellulose and hydroxypropyl methyl cellulose; the sodium silicate has a modulus of 2.0 to 2.4 or more; and the gypsum is 120 mesh to 150 mesh.

[0062] In summary, the combined effects of a low binder-to-aggregate ratio and cellulose ethers and amide polymers give the pressure-compacting repair mortar of this invention the characteristic of dry hardness. During construction, it is compacted using matching mechanical equipment. This handheld compactor can press loose repair mortar particles into a cohesive whole, filling defects such as localized peeling, flaking, cracks, and honeycomb pitting in the repaired substrate. The compressive strength is approximately 10–50 MPa, exhibiting high bonding strength and density even before the mortar is completely dry. This ensures good water penetration resistance and effectively inhibits the erosion of concrete by chloride ions and other corrosive ions in the external environment during service.

[0063] application

[0064] The pressurized compaction repair mortar of the present invention has the characteristic of being able to be formed into a ball by hand. It can be applied manually and compacted by pressure, which can give the repair material strong adhesion in the early stage. Furthermore, as the cementitious material slowly hydrates, the mechanical properties and bonding properties of the repair mortar are greatly improved after drying and hardening.

[0065] The cementitious material of the pressurized compaction repair mortar of the present invention is consistent with the type and gradation of fine aggregate and the composition of cementitious material of the concrete component being repaired. Therefore, the repair layer formed by the pressurized compaction repair mortar is consistent with the color of the concrete component being repaired and has no color difference. It can be used to fill the defects such as honeycomb, pitting, cracks, and exposed reinforcement in the concrete component being repaired, ensuring the integrity and aesthetics of the concrete structure.

[0066] The pressurized compaction repair mortar of the present invention is strongly alkaline, which acts as an active activator to promote the secondary hydration of cementitious materials in the repaired concrete component, improve the strength of key parts of the concrete, form a new whole, and effectively prevent secondary cracking. Therefore, the pressurized compaction repair mortar can be used for interface repair with high requirements for bond strength.

[0067] The pressurized compaction repair mortar of the present invention has excellent water-repellent and self-cleaning properties after hardening. Water is difficult to penetrate the building surface, and the waterproof effect is good. Surface dirt can be washed off with water. Therefore, the pressurized compaction repair mortar can be used for the repair of concrete components that require waterproofing or are difficult to clean, such as surface repair of concrete projects such as cooling towers and sewage treatment ponds.

[0068] The pressurized compaction repair mortar of this invention does not possess self-flowing properties, therefore, it can be used for repairs on vertical surfaces, top surfaces, locations where molds are difficult to install, and in confined spaces. For example, stress concentrations, irregular structures, and large-volume areas such as the connection between piers and beams in bridge concrete, expansion joints, and chamfers of box girders are prone to cracking. When repair and reinforcement are needed, workers can shape the dry-hardened mortar according to the actual required cross-sectional shape and size, achieving precise filling and improving the adhesion of the repair mortar and the overall integrity of the structure. This repair process does not require the construction of templates or the use of auxiliary tools and equipment such as pumps to control the flow of materials, saving repair time, improving overall construction efficiency, and enabling rapid repair of irregular bridge structures. Mechanical pressurization allows the pressurized compaction repair mortar of this invention to fully penetrate the pores of the substrate being repaired, reducing micro-gaps and loose areas at the bonding interface. Moisture is less likely to penetrate the bonding interface, thereby extending the service life of the bridge after repair and reinforcement.

[0069] Repair methods

[0070] This invention provides a method for repairing concrete interfaces, comprising:

[0071] Prepare the above-mentioned pressurized and compacted repair mortar;

[0072] Make the pressurized and compacted repair mortar come into contact with the interface being repaired;

[0073] Compact the pressure-dense repair mortar and allow it to cure naturally.

[0074] In some embodiments of the present invention, the interface to be repaired is located in one or more of the following: a vertical surface, a top surface, and a confined space.

[0075] In some embodiments of the present invention, preparing the above-mentioned pressurized and compacted repair mortar includes: pre-dry mixing the cementitious material and fine aggregate to obtain a solid material; adding the water-reducing agent and half of the water to the solid material and mechanically stirring to obtain a moist mixture; and simultaneously adding the modifier and the remaining water to the moist mixture and continuing to stir for a time of not less than 120 seconds.

[0076] In some embodiments of the present invention, bringing the pressurized compacted repair mortar into contact with the interface to be repaired includes:

[0077] (i) Place the repair mortar in a handheld mortar press and extrude it onto the surface to be repaired; or

[0078] ( ii Squeeze the repair mortar into a ball and press it onto the surface to be repaired.

[0079] In some embodiments of the present invention, the compaction strength of the pressurized and dense repair mortar is 10 to 50 MPa.

[0080] This concrete interface repair method can be applied to the aforementioned application scenarios.

[0081] Example

[0082] The technical solution of the present invention is described in detail below through examples. Unless otherwise specified, the raw materials, equipment, or solvents used are all commercially available. Unless otherwise specified, the raw materials with the same name used in the following examples and comparative examples are the same raw materials.

[0083] The cement used in the following examples is ordinary Portland cement—P·O52.5 grade cement, with a specific surface area of ​​350 m². 2 / kg; the fly ash used is Grade I fly ash, with a water requirement ratio of 94.2% and a sieve residue of 11.4% on a 45μm sieve; the mineral powder used is S95 grade slag powder with a specific surface area of ​​421m². 2 The particle size is mainly distributed between 1-13 μm, and the D50 is 3-5 μm. The modulus of sodium silicate is between 2.0 and 2.4; commercially available anhydrite is used, with the main chemical component being CaSO4 and a particle size of 120-150 mesh. The cellulose ether is methyl hydroxypropyl cellulose, and the amide polymer is polyacrylamide.

[0084] Example 1

[0085] The repair mortar provided in this embodiment is composed of the following raw materials:

[0086] 19.5 parts by weight of cement, 6 parts by weight of mineral powder, 4.5 parts by weight of fly ash, 3.9 parts by weight of sodium silicate, 0.5 parts by weight of gypsum, 0.35 parts by weight of methyl hydroxypropyl cellulose, 0.25 parts by weight of polyacrylamide, 65 parts by weight of river sand, 5.1 parts by weight of water, and 0.27 parts by weight of water-reducing agent.

[0087] The method for preparing repair mortar provided in this embodiment includes the following steps:

[0088] Cement, mineral powder, fly ash, and river sand are pre-dry mixed to obtain solid materials. Then, water-reducing agent and half of the water are added and mechanically stirred for about 60 seconds to obtain a moist mixture. Next, sodium silicate, gypsum, methyl hydroxypropyl cellulose, polyacrylamide, and water are added simultaneously and stirring is continued for at least 120 seconds. If the slurry is not homogeneous or too dry and hard at the end of stirring, the stirring time can be extended to 180 seconds and the amount of water-reducing agent can be adjusted. The repair mortar is obtained after stirring is completed.

[0089] Example 2

[0090] The repair mortar provided in this embodiment is composed of the following raw materials:

[0091] 19.5 parts by weight of cement, 6 parts by weight of mineral powder, 4.5 parts by weight of fly ash, 3.0 parts by weight of sodium silicate, 1.5 parts by weight of gypsum, 0.2 parts by weight of methyl hydroxypropyl cellulose, 0.3 parts by weight of polyacrylamide, 65 parts by weight of river sand, 5.4 parts by weight of water, and 0.25 parts by weight of water-reducing agent.

[0092] The preparation method of the repair mortar provided in this embodiment is the same as that in Embodiment 1.

[0093] Example 3

[0094] The repair mortar provided in this embodiment is composed of the following raw materials:

[0095] 16.9 parts by weight of cement, 5.2 parts by weight of mineral powder, 3.9 parts by weight of fly ash, 4.9 parts by weight of sodium silicate, 1.5 parts by weight of gypsum, 0.4 parts by weight of methyl hydroxypropyl cellulose, 0.2 parts by weight of polyacrylamide, 67 parts by weight of river sand, 4.9 parts by weight of water, and 0.22 parts by weight of water-reducing agent.

[0096] The preparation method of the repair mortar provided in this embodiment is the same as that in Embodiment 1.

[0097] Example 4

[0098] The repair mortar provided in this embodiment is composed of the following raw materials:

[0099] 16.25 parts by weight of cement, 5 parts by weight of mineral powder, 3.75 parts by weight of fly ash, 5.0 parts by weight of sodium silicate, 1.5 parts by weight of gypsum, 0.3 parts by weight of methyl hydroxypropyl cellulose, 0.2 parts by weight of polyacrylamide, 68 parts by weight of river sand, 5.0 parts by weight of water, and 0.25 parts by weight of water-reducing agent.

[0100] The preparation method of the repair mortar provided in this embodiment is the same as that in Embodiment 1.

[0101] Table 1 Raw material composition in each embodiment

[0102]

[0103]

[0104] Table 2 shows the performance of the repair mortars provided in each embodiment.

[0105]

[0106] Comparative Example 1

[0107] The repair mortar provided in this comparative example is composed of the following raw materials:

[0108] 19.5 parts by weight of cement, 6 parts by weight of mineral powder, 4.5 parts by weight of fly ash, 0.35 parts by weight of methyl hydroxypropyl cellulose, 0.25 parts by weight of polyacrylamide, 65 parts by weight of river sand, 5.1 parts by weight of water, and 0.27 parts by weight of water-reducing agent.

[0109] The preparation method of the repair mortar provided in this comparative example is the same as that in Example 1.

[0110] Comparative Example 2

[0111] The repair mortar provided in this comparative example is composed of the following raw materials:

[0112] 19.5 parts by weight of cement, 6 parts by weight of mineral powder, 4.5 parts by weight of fly ash, 3.9 parts by weight of sodium silicate, 0.5 parts by weight of gypsum, 65 parts by weight of river sand, 5.1 parts by weight of water, and 0.27 parts by weight of water-reducing agent.

[0113] The preparation method of the repair mortar provided in this comparative example is the same as that in Example 1.

[0114] Comparative Example 3

[0115] The repair mortar provided in this comparative example is composed of the following raw materials:

[0116] 32.5 parts by weight of cement, 10 parts by weight of mineral powder, 7.5 parts by weight of fly ash, 3.9 parts by weight of sodium silicate, 0.5 parts by weight of gypsum, 0.35 parts by weight of methyl hydroxypropyl cellulose, 0.25 parts by weight of polyacrylamide, 50 parts by weight of river sand, 8.5 parts by weight of water, and 0.25 parts by weight of water-reducing agent.

[0117] The preparation method of the repair mortar provided in this comparative example is the same as that in Example 1.

[0118] Comparative Example 4

[0119] The repair mortar provided in this comparative example is composed of the following raw materials:

[0120] 19.5 parts by weight of cement, 6 parts by weight of mineral powder, 4.5 parts by weight of fly ash, 5 parts by weight of sodium silicate, 0.35 parts by weight of methyl hydroxypropyl cellulose, 0.25 parts by weight of polyacrylamide, 64.4 parts by weight of river sand, 5.1 parts by weight of water, and 0.27 parts by weight of water-reducing agent.

[0121] The preparation method of the repair mortar provided in this comparative example is the same as that in Example 1.

[0122] Comparative Example 5

[0123] The repair mortar provided in this comparative example is composed of the following raw materials:

[0124] 19.5 parts by weight of cement, 6 parts by weight of mineral powder, 4.5 parts by weight of fly ash, 1.4 parts by weight of gypsum, 0.35 parts by weight of methyl hydroxypropyl cellulose, 0.25 parts by weight of polyacrylamide, 68 parts by weight of river sand, 5.1 parts by weight of water, and 0.27 parts by weight of water-reducing agent.

[0125] The preparation method of the repair mortar provided in this comparative example is the same as that in Example 1.

[0126] Comparative Example 6

[0127] The repair mortar provided in this comparative example is composed of the following raw materials:

[0128] 19.5 parts by weight of cement, 6 parts by weight of mineral powder, 4.5 parts by weight of fly ash, 3.9 parts by weight of sodium silicate, 0.5 parts by weight of gypsum, 0.6 parts by weight of methyl hydroxypropyl cellulose, 65 parts by weight of river sand, 5.1 parts by weight of water, and 0.27 parts by weight of water-reducing agent.

[0129] The preparation method of the repair mortar provided in this comparative example is the same as that in Example 1.

[0130] Comparative Example 7

[0131] The repair mortar provided in this comparative example is composed of the following raw materials:

[0132] The composition includes 19.5 parts by weight of cement, 6 parts by weight of mineral powder, 4.5 parts by weight of fly ash, 3.9 parts by weight of sodium silicate, 0.5 parts by weight of gypsum, 0.6 parts by weight of polyacrylamide, 65 parts by weight of river sand, 5.1 parts by weight of water, and 0.27 parts by weight of water-reducing agent.

[0133] The preparation method of the repair mortar provided in this comparative example is the same as that in Example 1.

[0134] Table 3. Raw material composition in Example 1 and Comparative Example

[0135]

[0136]

[0137] Table 4 shows the physical performance test results of the repair mortar and the specimens made from it in Example 1 and each comparative example. The test method is in accordance with the specific requirements of "JG / T 336-2011 Technical Requirements for Polymer Cement Mortar for Concrete Structure Repair", and the test is performed using Type A index.

[0138] The 1-day and 28-day compressive and flexural strength tests were conducted according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-1999). The specimen size was 40mm×40mm×160mm. The specimens were prepared according to the raw material composition in Table 1. Then, the freshly mixed dry hard material was compacted in the mortar mold by a stamping machine to ensure that the mass of a single specimen was between 0.7 and 0.75 kg.

[0139] Similarly, the 56-day shrinkage test was conducted using the contact method in the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T50082-2009). The specimens were molded to a size of 100mm×100mm×400mm and prepared according to the raw material composition in Table 1. The freshly mixed cement mortar was then compacted in a steel mold using a stamping press to ensure that the mass of each specimen was between 10.8 and 11.5 kg.

[0140] Table 4

[0141]

[0142]

[0143] As shown in Example 1, the specimens obtained by the repair mortar of the present invention have high compressive and flexural strength, low 56-day shrinkage, and the repair mortar has high 28-day bond strength with the concrete to be repaired, and good impermeability.

[0144] As shown in Comparative Example 1, after omitting sodium silicate and gypsum in Comparative Example 1, the strength of the specimen itself decreased significantly, and the 28-day bond strength between the repair layer and the repaired concrete component also decreased severely, although the 56-day shrinkage rate was smaller. This is because without the active activating component, the cementitious materials in the repair mortar did not hydrate completely, resulting in a significant decrease in early strength. Furthermore, compared to Comparative Example 1, the mortar did not generate Na₂SO₄; the products formed after the chemical reaction of CaSiO₄ with cement and mineral powder have a certain degree of viscosity, further improving the bonding performance.

[0145] As shown in Comparative Example 2, although the present invention improves the strength of the specimen itself by omitting methyl hydroxypropyl cellulose and polyacrylamide compared to Example 1, the 28-day bond strength between the repair layer and the repaired concrete component decreases significantly, the 56-day shrinkage rate increases, and water seepage is more likely to occur. This is because methyl hydroxypropyl cellulose and polyacrylamide, these two types of polymer particles, have good compatibility with cement-based materials and will deposit or agglomerate on the surface of hydrated cement and aggregates, forming a thin film. This film will form an interpenetrating network structure with the cement hydration products. Although this film will slightly hinder the hydration of cement particles and reduce the mechanical properties of the mortar, it will give the mortar a water-retention effect and increase the consistency of the freshly mixed mortar. Without this component, the mortar lacks a flexible network structure and does not have obvious dry-hardness characteristics. The mechanical properties are enhanced, but the fluidity increases, and the bond strength of the slurry is lower.

[0146] As shown in Comparative Example 3, in the present invention, after increasing the binder-aggregate ratio to 1 while keeping the water-cement ratio constant compared to Example 1, the 56-day shrinkage rate significantly increased. This is because, on the one hand, the decrease in aggregate content leads to a reduction in its deformation-restraining effect; on the other hand, the increase in the amount of binder results in a corresponding increase in the amount of hydration reaction, leading to greater water consumption, smaller volume of hydration products, and more pronounced drying shrinkage. The 28-day bond strength between the repair layer and the repaired concrete component also decreased slightly, because increased mortar shrinkage also has an adverse effect on bond strength.

[0147] As shown in Comparative Examples 4 to 7, when any one of sodium silicate, gypsum, methyl hydroxypropyl cellulose, or polyacrylamide is missing from the modifier, the 28-day bond strength between the repair layer and the repaired concrete component decreases. In addition, the compressive strength and flexural strength of the specimen itself also decrease.

[0148] When the active activating component in the modifier lacks either sodium silicate or gypsum, the compressive and flexural strengths of the repair mortar will decrease; while when the tackifying component lacks either methyl hydroxypropyl cellulose or polyacrylamide, the synergistic effect is lost, resulting in a significant decrease in the 28-day bond strength between the repair material and the repaired concrete component.

[0149] When repairing concrete components using the repair mortar prepared by this invention, there is no need to chemically treat the interface to be repaired. After cleaning the interface to be repaired, the repair mortar is applied to the area that needs to be repaired, and the mortar is compacted by manual pressure equipment. The surface of the repair mortar is then smoothed and cured to the specified age before it can be put into use.

[0150] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A pressure-compacting repair mortar, characterized in that, Including the following raw materials: The cementitious material is added at a dosage of 25wt%~30wt% of the repair mortar. Fine aggregate, with a dosage of 65wt%~68wt% of the repair mortar; The active activating component, composed of sodium silicate and gypsum, is added at a dosage of 4.4 wt% to 6.5 wt% of the repair mortar. The thickening component, composed of cellulose ethers and amide polymers, is added at a dosage of 0.4wt%~0.6wt% of the repair mortar. Water-reducing agent, the dosage of which is 0.5wt%~1wt% of cementitious material; Water, at a dosage of 17wt%~20wt% of the cementitious material; The water-to-gel ratio is 0.17-0.2, and the glue-to-bond ratio is 0.37-0.

46.

2. The pressurized compaction repair mortar according to claim 1, characterized in that: The pressurized compaction repair mortar has the same type of fine aggregate and cementitious material composition as the concrete component being repaired.

3. The pressurized compaction repair mortar according to claim 1, characterized in that: The water-to-binder ratio is 0.17~0.18, and the glue-to-bone ratio is 0.

46.

4. The pressurized compaction repair mortar according to claim 1, characterized in that: The dosage of cellulose ether is 0.2wt%~0.4wt% of the repair mortar; The weight-average molecular weight of amide polymers is 6 million to 10 million, and the dosage is 0.2 wt% to 0.3 wt% of the repair mortar. The dosage of sodium silicate is 3wt%~5wt% of the repair mortar; The amount of gypsum added is 0.5wt% to 1.5wt% of the repair mortar.

5. The pressurized compaction repair mortar according to claim 1 or 4, characterized in that: The amide polymer is polyacrylamide; the cellulose ether is one or more of carboxymethyl cellulose and hydroxypropyl methyl cellulose; the sodium silicate has a modulus of one or more of 2.0 to 2.4; and the gypsum has a particle size of 120 mesh to 150 mesh.

6. A method for repairing concrete interfaces, characterized in that, include: Prepare the pressurized compaction repair mortar as described in any one of claims 1 to 5; Make the pressurized and compacted repair mortar come into contact with the interface being repaired; Compact the pressure-dense repair mortar and allow it to cure naturally.

7. The concrete interface repair method according to claim 6, characterized in that: The interface to be repaired is located in one or more of the following: a vertical surface, a top surface, or a confined space.

8. The concrete interface repair method according to claim 6, characterized in that: Preparing the pressurized compaction repair mortar according to any one of claims 1 to 5 includes: The cementitious materials and fine aggregates are pre-dry mixed to obtain solid materials; Add the water-reducing agent and half the water to the solid material and mechanically stir to obtain a moist mixture; Add the active activating component, thickening component and remaining water to the moistened mixture and continue stirring for at least 120 seconds.

9. The concrete interface repair method according to claim 6, characterized in that: Making the pressurized and compacted repair mortar come into contact with the interface being repaired includes: Place the repair mortar in a handheld press and extrude it onto the surface to be repaired; or... Squeeze the repair mortar into a ball and press it onto the surface to be repaired.

10. The concrete interface repair method according to claim 6, characterized in that: The compaction strength used for the pressure-dense repair mortar is 10~50MPa.

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