ECC fireproof repair material, preparation method and application

Abstract

The invention provides an ECC fireproof repair material, a preparation method and application, and belongs to the technical field of building materials. The ECC fireproof repair material comprises the following raw materials: an inorganic gel material, an alkali activator, PVA fibers and water. The alkali activator accelerates the hydration reaction of the inorganic gel material and changes the microstructure of the inorganic gel material, so that the material has the characteristics of rapid hardening and early strength. The PVA fiber is added, so that the material has quick hardening property and stable volume, and does not shrink due to quick hardening. Meanwhile, the PVA fibers can be gradually decomposed at a high temperature and pores are reserved, and water vapor generated in the material at the high temperature is discharged through the pores, so that the material has fire resistance and does not crack at the high temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and specifically relates to an ECC fireproof repair material, a preparation method and an application thereof. Background Art

[0002] In the modern construction industry, concrete, as one of the most widely used building materials, has become an indispensable basic material for various building structures due to its good compressive resistance, durability and economy. From high-rise buildings to bridges and roads, from water conservancy facilities to underground projects, concrete, with its solid characteristics, supports the skeleton of modern buildings and provides a solid guarantee for people's lives and social development.

[0003] However, concrete structures will inevitably be damaged during long-term use due to various factors. For example, temperature changes, humidity fluctuations, freeze-thaw cycles, and chemical erosion such as acid rain and industrial wastewater in the natural environment will gradually destroy the structure of concrete. At the same time, the repeated effects of traffic loads, especially the frequent rolling of roads and bridges by heavy vehicles, will also accelerate the damage of concrete. These damages not only affect the beauty of the building structure, but also seriously threaten its safety and service life.

[0004] At present, there are a variety of repair materials and methods on the market for the repair of damaged concrete. Although traditional cement mortar repair materials are low in cost, they have problems with insufficient compressive strength and slow hardening speed, making it difficult to meet engineering scenarios that require rapid repair and high strength. Although some organic polymer repair materials have certain advantages in bonding performance, they often have poor volume stability and are prone to shrinkage or expansion under the influence of environmental factors, causing the repaired parts to crack again, affecting the repair effect. In addition, existing repair materials are difficult to achieve a balance between high compressive strength, rapid hardening and good volume stability in terms of comprehensive performance, and cannot fully meet the stringent requirements of modern construction projects for concrete repair materials.

[0005] In view of the above-mentioned deficiencies in the existing technology, it is urgent to develop a new type of repair material that can effectively repair damaged concrete and has high compressive strength, rapid hardening and good volume stability. Summary of the invention

[0006] In view of the technical problems existing in the prior art, the present invention aims to provide an ECC fireproof repair material, a preparation method and an application thereof.

[0007] One of the purposes of the present invention is to provide an ECC fireproof repair material. The raw materials of the ECC fireproof repair material include an inorganic gel material, an alkali activator, PVA fiber and water. Preferably, the mass ratio of water to the inorganic gel material is 0.4-0.6:1.

[0008] Preferably, the mass ratio of the alkali activator to the inorganic gel material is 0.15-0.2:1.

[0009] Preferably, the mass ratio of the alkali activator to the inorganic gel material is 0.18.

[0010] Preferably, the inorganic gel material includes one or more of mineral powder, river sand or cement.

[0011] Preferably, the inorganic gel material includes mineral powder and river sand, and the mass ratio of the mineral powder to the river sand is 1.2-1.3:1.

[0012] Preferably, the mass ratio of mineral powder to river sand is 1.25:1.

[0013] Preferably, the alkali activator includes a silicate alkali activator and an alkali hydroxide activator.

[0014] Preferably, the silicate alkali activator includes sodium silicate and / or potassium silicate, and the alkaline hydroxide activator includes sodium hydroxide and / or potassium hydroxide.

[0015] Preferably, the mass percentage of PVA fiber is 1.5-2.5%.

[0016] Preferably, the mass percentage of PVA fiber is 2%.

[0017] The second object of the present invention is to provide a method for preparing an ECC fireproof repair material, the preparation method comprising: First, a silicate alkali activator is fully mixed with water, and then an alkaline hydroxide activator is added and stirred until it is completely dissolved, and then allowed to stand until it becomes colorless and transparent, thereby obtaining an alkali activator; The inorganic gel material and PVA fiber are fully mixed and then an alkali activator is slowly added to obtain the ECC fireproof repair material.

[0018] A third object of the present invention is to provide an application of an ECC fireproof repair material in concrete repair.

[0019] Beneficial effects of the present invention: The present invention provides an ECC fireproof repair material, which is prepared from an inorganic gel material, an alkali activator, PVA fibers and water. The alkali activator accelerates the hydration reaction of the inorganic gel material, changes the microstructure of the inorganic gel material, and makes the material have the characteristics of fast hardening and early strength. The addition of PVA fibers makes the material stable in volume while having fast hardening properties, and will not shrink due to rapid hardening. At the same time, the PVA fibers will gradually decompose at high temperatures and leave pores, and the water vapor generated inside the material at high temperatures will be discharged through the pores, so that the material has fire resistance and does not crack at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The failure modes of the ECC fire repair material and concrete specimens at 400°C; Figure 2 The failure modes of the ECC fire repair material and concrete specimens at 600°C; Figure 3 This is the failure morphology of the ECC fire repair material and concrete specimens at 800°C. DETAILED DESCRIPTION

[0021] According to the first aspect of the present invention, an ECC fireproof repair material is provided. The raw materials of the ECC fireproof repair material include an inorganic gel material, an alkali activator, PVA fibers and water. In the present invention, the inorganic gel material itself has potential hydraulic activity, and its activity can be rapidly activated under the action of an alkali activator. Inorganic gel materials such as slag and fly ash contain a large amount of active silicon oxide and aluminum oxide, and under the action of an alkali activator, these components can rapidly react with water to generate a gelling substance, providing early strength for the material.

[0022] Alkali activators can significantly accelerate the hydration reaction of inorganic gel materials. Generally speaking, the hydration reaction of traditional cement is relatively slow, and the alkaline substances in alkali activators, such as sodium hydroxide and sodium silicate, can provide a large number of hydroxide ions, which will react quickly with the active ingredients in inorganic gel materials, such as aluminosilicates, to form products with gelling properties, thereby greatly shortening the setting time of the material and enabling it to obtain higher strength in a short time.

[0023] Alkali activators can also change the microstructure of inorganic gel materials, making the hydration products they generate denser and more uniform, thereby improving the early compressive strength of the material. Under the action of alkali activation, more gel substances such as amorphous silicate hydrates will be generated, which can quickly fill the pores inside the material and enhance the structural stability of the material, thereby making the compressive strength of the material significantly higher than that of ordinary cement material samples after a curing time of 4 hours.

[0024] In the present invention, the chemical composition and microstructure of the products generated by the reaction of the alkali activator and the inorganic gel material are different from those of the hydration products of ordinary cement. These reaction products can form a relatively stable network structure during the formation process. This structure has good anti-deformation ability and will not produce excessive shrinkage stress due to rapid hardening, thereby ensuring the volume stability of the material during the rapid hardening process.

[0025] In addition, PVA fibers have good flexibility and high strength, and are evenly distributed in ECC repair materials. When the material may generate internal stress due to rapid reaction during the coagulation and hardening process, PVA fibers can play a bridging and crack-blocking role. It can withstand part of the internal stress and prevent the generation and expansion of microcracks, thereby avoiding shrinkage cracks in the material due to stress concentration and ensuring the volume stability of the material.

[0026] PVA fiber can also improve the internal interface structure of the material, enhance the bonding force between the inorganic gel material and other components, make the overall structure of the material more compact and stable, and further reduce the possibility of volume shrinkage.

[0027] In the present invention, PVA fiber can improve the toughness and crack resistance of the material at room temperature, and also plays an important role in high temperature environment. Although the melting point of PVA fiber itself is relatively low, it will gradually decompose and leave pores at high temperature in ECC repair materials. These pores can provide a discharge channel for water vapor and other gases generated inside the material at high temperature, thereby reducing the vapor pressure inside the material and reducing the possibility of cracking caused by pressure accumulation. During the decomposition process, PVA fiber will form a special interface structure with the inorganic gel material. This structure can play a certain buffering role at high temperature, absorb and disperse the energy generated by thermal stress inside the material, and prevent the generation and expansion of cracks.

[0028] After the inorganic gel material, alkali activator and PVA fiber interact with water, a uniform, dense and flexible microstructure is formed. This structure can maintain good integrity and stability at high temperatures, and the various components can work together to resist the effects of thermal stress.

[0029] The product generated by the reaction of the alkali activator and the inorganic gel material fills the pores inside the material, making the material structure denser and reducing the uneven volume change caused by temperature changes, thereby reducing the risk of cracking. At the same time, the presence of PVA fibers enhances the toughness of the material, allowing the material to consume energy through fiber stretching and deformation when subjected to thermal stress, thus avoiding the generation of cracks.

[0030] Many inorganic gel materials have good high temperature resistance, such as slag and fly ash. Their main components are minerals such as silicate. These minerals have high stability at high temperatures and can withstand high temperatures without obvious melting or decomposition. They provide a basic refractory skeleton for ECC repair materials, allowing them to maintain a certain structural integrity under high temperature environments. Inorganic gel materials will undergo some physical and chemical changes at high temperatures. For example, the crystal water inside them will gradually be lost, and the crystal structure will be adjusted to form a more stable high temperature resistant phase, further improving the fire resistance of the material.

[0031] The products generated by the reaction of the alkali activator and the inorganic gel material have a special chemical composition and microstructure. These products can form a dense ceramic structure at high temperatures. This structure has good thermal insulation and high temperature resistance, can prevent the rapid transfer of heat, slow down the temperature rise rate inside the material, and thus improve the fire resistance of the material. The products generated by the alkali activating reaction can inhibit the melting and volatilization of some fusible components in the inorganic gel material at high temperatures, so that the material can maintain good stability at high temperatures and is not prone to softening and deformation.

[0032] In a preferred embodiment of the present invention, the mass ratio of water to the inorganic gel material is 0.4-0.6:1.

[0033] In the present invention, the mass ratio of water to the inorganic gel material is, for example, 0.4:1, 0.45:1, 0.5:1, 0.55:1 or 0.6:1.

[0034] In the present invention, water is used as a solvent and reaction medium to fully dissolve the alkaline activator and ionize active ions such as hydroxide ions. These ions react quickly with the active ingredients in the inorganic gel material to form hydration products and gel substances with early strength, thereby achieving rapid hardening and early strength. If the water content is lower than 0.4:1, the alkaline activator cannot be fully dissolved and diffused, the reaction rate is limited, and it is difficult to quickly form sufficient strength; and if the water content is higher than 0.6:1, the concentration of the alkaline activator and the inorganic gel material will be diluted, the reaction rate will be reduced, and it is not conducive to the rapid development of early strength.

[0035] The mass ratio of water to inorganic gel material is in the range of 0.4~0.6:1, which can ensure that the hydration reaction and alkali excitation reaction of the inorganic gel material proceed to a certain extent in a short period of time, generating sufficient gel substances and crystalline products such as hydrated calcium silicate and hydrated calcium aluminate to fill the internal pores of the material, improve the density of the material, and thus obtain higher compressive strength at an early stage such as 4h.

[0036] The mass ratio of 0.4~0.6:1 can make the hydration reaction and alkali excitation reaction proceed smoothly and orderly. When the amount of water is 0.4~0.6:1, the reaction speed is moderate, and excessive internal stress will not be generated due to excessive reaction, causing material shrinkage. If there is too much water, the reaction will be too violent, and a large amount of heat and hydration products will be generated in a short time. The water inside the material evaporates too quickly, causing a large volume shrinkage; if there is too little water, the reaction is incomplete, and the reaction may continue to produce volume changes in the later stage, affecting the volume stability of the material.

[0037] The right amount of water forms a relatively stable humidity environment inside the material, which helps maintain the moisture balance inside the material. During the hydration reaction, the slow consumption and evaporation of water can cause the material to gradually dry and shrink during the hardening process. However, since the water content is controlled within a reasonable range, there will be no sharp shrinkage caused by rapid loss of water, thus ensuring the volume stability of the material.

[0038] At a mass ratio of 0.4 to 0.6:1, the products generated by the hydration reaction and the alkali-induced reaction can form a uniform, dense and stable microstructure. This structure can maintain good integrity at high temperatures, providing a good fire-resistant foundation for the material. When the material is subjected to high temperatures, the water in the structure will gradually evaporate, but due to the appropriate water content, a large number of pores and cracks will not be generated due to the rapid evaporation of water, thereby maintaining the overall structural stability of the material and improving fire resistance.

[0039] The water content at a mass ratio of 0.4 to 0.6:1 helps to form a good interface between the inorganic gel material and other components such as PVA fibers. At high temperatures, this interface can effectively transfer stress, so that when the material is subjected to thermal stress, the various components can work together to resist thermal stress and avoid cracking caused by concentrated thermal stress. If the water content is too much or too little, it will affect the quality of the interface and reduce the material's crack resistance at high temperatures.

[0040] In a preferred embodiment of the present invention, the mass ratio of the base activator to the inorganic gel material is 0.15-0.2:1.

[0041] In the present invention, the alkaline activator can provide a large amount of active substances such as hydroxide ions. When the mass ratio of the alkaline activator to the inorganic gel material is in the range of 0.15~0.2:1, these active substances can quickly react with the active ingredients in the inorganic gel material, break the chemical bonds of the inorganic gel material, make it quickly dissolve and release active ions such as silicon and aluminum, thereby accelerating the hydration reaction and gelation process, so that the material can obtain higher strength in a short time, and achieve rapid hardening and early strength.

[0042] The appropriate proportion of alkaline activator can make the reaction continue and the reaction degree is high. At this ratio, the alkaline environment provided by the alkaline activator is conducive to promoting the further hydration and polymerization reaction of the inorganic gel material, generating more hydration products and gel substances, such as aluminosilicate gel, etc. These products can fill the pores inside the material, enhance the density and strength of the material, and show good mechanical properties at an early stage.

[0043] In the present invention, when the mass ratio of the alkali activator to the inorganic gel material is 0.15 to 0.2:1, the reaction rate is moderate. If the amount of the alkali activator is less than 0.15:1, the reaction is incomplete, and the reaction may continue in the later stage, resulting in volume changes; and if the amount is higher than 0.2:1, the reaction is too intense, and a large amount of heat and hydration products will be generated in a short time, resulting in internal stress concentration of the material, which is easy to cause volume shrinkage or expansion. The appropriate ratio can make the reaction proceed smoothly, reduce the internal stress caused by the unbalanced reaction, and thus ensure the volume stability of the material.

[0044] Within this ratio range, the structure of the generated hydration products and gel substances is more uniform and stable. They can form an interwoven and tightly arranged network structure inside the material, which can effectively resist the volume change caused by external factors, so that the material maintains a relatively stable volume during the hardening process, and will not shrink significantly due to rapid hardening.

[0045] After the appropriate proportion of alkali activator reacts with the inorganic gel material, gel products and crystalline phases such as silicate with high high temperature resistance can be generated. These products can maintain good stability at high temperatures, forming a strong skeleton structure, providing a good fire-resistant foundation for the material and improving the fire resistance of the material. At a mass ratio of 0.15~0.2:1, the microstructure inside the material is more dense and uniform, and the porosity is lower. This enables the material to better resist heat transfer at high temperatures, reduce the rapid conduction of heat, and reduce the thermal stress generated by temperature changes inside the material. At the same time, the uniform structure also helps to evenly distribute stress and avoid cracking caused by concentrated thermal stress, so that the material can still maintain structural integrity and not crack after high-temperature combustion.

[0046] In the present invention, the mass ratio of the alkali activator to the inorganic gel material is, for example, 0.15:1, 0.16:1, 0.17:1, 0.18:1, 0.19:1 or 0.20:1.

[0047] In a preferred embodiment of the present invention, the mass ratio of the alkali activator to the inorganic gel material is 0.18:1.

[0048] In a preferred embodiment of the present invention, the inorganic gel material includes one or more of mineral powder, river sand or cement.

[0049] In the present invention, the inorganic gel material is, for example, mineral powder, river sand, cement, mineral powder and river sand, mineral powder and cement, river sand and cement, or mineral powder, river sand and cement.

[0050] In a preferred embodiment of the present invention, the inorganic gel material includes mineral powder and river sand, and the mass ratio of the mineral powder to the river sand is 1.2-1.3:1.

[0051] In the present invention, the mineral powder has high activity. Under the action of alkali activator and water, a series of chemical reactions such as volcanic ash reaction can occur to generate gelling substances, such as calcium silicate gel, etc. These substances can fill the internal pores of the material and improve the density of the material, thereby providing a higher strength for the material. When the ratio of mineral powder to river sand is 1.2-1.3:1, the gelling substances produced are sufficient to firmly bond aggregates such as river sand together to form a stable structure, so that the material can obtain better mechanical properties such as compressive strength at an early stage, meeting the requirements of rapid hardening and early strength.

[0052] The volume change of mineral powder during the hydration reaction is relatively small, while river sand, as an inert aggregate, can limit the excessive expansion or contraction of the mineral powder hydration products to a certain extent. When mineral powder and river sand are mixed in a ratio of 1.2~1.3:1, the two cooperate with each other to enable the material to maintain good volume stability during the hardening process, avoiding defects such as cracks caused by excessive volume changes.

[0053] Mineral powder particles are generally fine, while river sand particles are relatively coarse. Mixing the two in a certain proportion can form a good particle gradation. When the mass ratio of mineral powder to river sand is 1.2~1.3:1, the particle distribution in the material can be more reasonable, coarse and fine particles fill each other, and the voids inside the material can be reduced, so that the material has good workability and is convenient for construction operations such as mixing, pouring, and screeding. The appropriate ratio can make the material form a uniform slurry during the mixing process. The slurry can be evenly wrapped on the surface of the river sand particles, reducing the friction between the particles, making the material have better fluidity, and can better fill the template and gaps during the construction process to ensure the repair effect.

[0054] Mineral powder has a certain water retention capacity, while river sand has a relatively weak water retention capacity. At a mass ratio of 1.2~1.3:1, mineral powder can absorb a certain amount of water, prevent water from being lost too quickly, and keep the material at a certain humidity during the construction process, which is conducive to the continuous hydration reaction. At the same time, it can also avoid problems such as surface drying and cracking caused by too fast evaporation of water.

[0055] The structure formed by the appropriate proportion of mineral powder and river sand is more compact, which can effectively block the intrusion of moisture, oxygen, harmful ions, etc. in the external environment. The gel substance generated by the hydration of mineral powder can fill the pores between river sand particles, forming a barrier, improving the material's impermeability and erosion resistance, thereby enhancing the material's durability, enabling it to maintain stable performance during long-term use and better function in harsh environments such as high temperature.

[0056] In a high temperature environment, this ratio of mineral powder and river sand can form a relatively stable structure inside the material. Mineral powder will undergo some physical and chemical changes such as crystal phase transformation at high temperatures, but its synergistic effect with river sand can enable the material to withstand high temperatures to a certain extent without cracking. The presence of river sand can disperse heat and reduce the thermal stress concentration of mineral powder at high temperatures, while the gelling material produced by mineral powder can still maintain a certain degree of adhesion at high temperatures, bonding the river sand particles together, jointly maintaining the structural integrity of the material, and improving the material's fire resistance and high temperature stability.

[0057] In the present invention, the mass ratio of mineral powder to river sand is, for example, 1.2:1, 1.21:1, 1.22:1, 1.23:1, 1.24:1, 1.25:1, 1.26:1, 1.27:1, 1.28:1, 1.29:1 or 1.3:1.

[0058] In a preferred embodiment of the present invention, the alkali activator includes a silicate alkali activator and an alkaline hydroxide activator.

[0059] In the present invention, silicate alkali activators dissolve in water, releasing silicate ions with high chemical activity, which can react chemically with aluminum ions, calcium ions, etc. in inorganic gel materials. In an alkaline environment, the two react to form aluminosilicate gel through polymerization. This type of gel firmly bonds mineral powder, river sand, etc., improving the strength and integrity of the material. At the same time, it can also adjust the hydration reaction speed of inorganic gel materials, promote the hydration of mineral powder and other materials, achieve rapid hardening and early strength, and the reaction speed and degree can be adjusted according to demand.

[0060] Alkaline hydroxide activators are completely ionized in water, producing a large number of hydroxide ions and creating a strong alkaline environment, which is the key to stimulating the activity of inorganic gel materials. Under alkaline conditions, insoluble substances are more easily dissolved and release active ions. Hydroxyl ions can attack the chemical bonds of the vitreous structure in inorganic gel materials, activate them, release active ions, accelerate the hardening of materials, and improve early strength. In addition, it can also promote the hydration reaction of inorganic gel materials, accelerate the hydration of mineral phases in cement, and generate more hydration products. These products are intertwined to fill pores and improve the density, strength, volume stability and durability of materials.

[0061] In a preferred embodiment of the present invention, the silicate alkali activator includes sodium silicate and / or potassium silicate, and the alkaline hydroxide activator includes sodium hydroxide and / or potassium hydroxide.

[0062] In a preferred embodiment of the present invention, the mass percentage of PVA fiber is 1.5-2.5%.

[0063] In the present invention, PVA fiber has high strength and modulus. When it is added to the material in an appropriate proportion, it can effectively bear external loads and prevent the generation and expansion of cracks. Within this mass percentage range, PVA fiber can form a uniform network structure inside the material, tightly combined with the matrix such as inorganic gel material, thereby significantly improving the tensile strength of the material. If the PVA fiber content is too low, such as less than 1.5%, the number of fibers is insufficient to form an effective load-bearing network, and the effect of improving the tensile strength is not obvious; if the content is too high, such as more than 2.5%, the fibers may be entangled and agglomerated with each other, which in turn affects the bonding effect between the fibers and the matrix, resulting in an insignificant increase or even a decrease in the tensile strength.

[0064] PVA fibers can absorb and dissipate energy through their own deformation and pull-out mechanisms when the material is subjected to external forces. Within the mass percentage range of 1.5% to 2.5%, the fibers can bridge the two sides of the cracks after microcracks appear in the material, limiting the further expansion of the cracks and giving the material good toughness and crack resistance. When the fiber content is less than 1.5%, the bridging effect provided by the fibers is limited, and the material is prone to brittle failure; when the content exceeds 2.5%, a weak interface may be formed in the matrix due to excessive fibers, reducing the overall crack resistance of the material.

[0065] A mass percentage of 1.5% to 2.5% is conducive to the uniform dispersion of PVA fibers in the material. During the stirring process, this proportion of fibers can be distributed more evenly in the matrix to avoid fiber agglomeration, thereby ensuring the uniformity of material performance. If the fiber content is too high, the interaction between the fibers is enhanced, and agglomeration is likely to occur, resulting in large differences in local material performance; if the content is too low, the performance improvement effect brought about by the uniform distribution of fibers cannot be reflected.

[0066] In the mass percentage range of 1.5% to 2.5%, PVA fibers will soften and melt before the matrix material in a high temperature environment. In this process, PVA fibers can absorb a certain amount of heat, play a buffering role, and slow down the transfer of heat to the inside of the material, thereby improving the fire resistance of the material to a certain extent. Most importantly, the softening and melting of the fibers will form some tiny pores and channels inside the material. These pores and channels can serve as gas discharge channels at high temperatures, relieve the pressure generated by gas expansion inside the material, and reduce the possibility of the material bursting at high temperatures.

[0067] A proper amount of PVA fiber can enhance the mechanical properties of the material at room temperature, making the material have higher strength and toughness. When the material is exposed to high temperature, although the PVA fiber will soften, it can still play a certain role in connecting and strengthening the material within a certain period of time, helping to maintain the structural integrity of the material and prevent the material from collapsing or breaking rapidly at high temperature, thereby improving the fire resistance limit of the material.

[0068] When the PVA fiber content is less than 1.5%, the buffering effect and connection reinforcement effect provided by the fiber at high temperature are very limited. The material may heat up rapidly at high temperature, and the internal gas cannot be effectively discharged, which may easily cause cracks and peeling in the material, seriously affecting the fire resistance of the material and reducing the stability and safety of the material in fire. If the PVA fiber content exceeds 2.5%, on the one hand, too much fiber will produce a large number of pores and channels when softening and melting at high temperature. These pores and channels may be interconnected to form large defects, which will reduce the density of the material, make it easier for heat to enter the material, and accelerate the destruction of the material. On the other hand, too many fibers may affect the proportion and distribution of other components in the material, change the thermal properties and physical structure of the material, and cause the material to be unstable at high temperature and reduce fire resistance.

[0069] According to the second aspect of the present invention, a method for preparing an ECC fireproof repair material is provided, characterized in that the preparation method comprises: First, a silicate alkali activator is fully mixed with water, and then an alkaline hydroxide activator is added and stirred until it is completely dissolved, and then allowed to stand until it becomes colorless and transparent, thereby obtaining an alkali activator; The inorganic gel material and PVA fiber are fully mixed and then an alkali activator is slowly added to obtain the ECC fireproof repair material.

[0070] According to the third aspect of the present invention, there is provided an application of an ECC fireproof repair material in concrete repair.

[0071] Example The present invention provides 5 embodiments and 5 comparative examples, wherein comparative example 5 is ordinary concrete, and the raw materials and addition amounts of embodiments 1 to 5 and comparative examples 1 to 4 are shown in Table 1.

[0072] Table 1 Raw materials and addition amounts of Examples 1 to 5 and Comparative Examples 1 to 4

[0073] The chemical composition of the mineral powder is shown in Table 2, the properties of the river sand are shown in Table 3, and the parameters of the PVA fiber are shown in Table 4.

[0074] Table 2 Chemical composition of mineral powder

[0075] Table 3 River sand properties

[0076] Table 4 PVA fiber parameters

[0077] The ECC fireproof repair materials of Examples 1 to 5 and Comparative Examples 1 to 4 were prepared according to the following method: First, mix sodium silicate and water thoroughly, then add sodium hydroxide and stir until completely dissolved, and let stand until it becomes colorless and transparent to obtain an alkaline activator.

[0078] The mineral powder, river sand and PVA fiber are fully mixed and then the alkali activator is slowly added to obtain the ECC fireproof repair material.

[0079] Performance Testing The ECC fireproof repair materials prepared in the comparative examples of each embodiment were cured, and the compressive strength was tested on the fourth and 28th days of curing; and the drying shrinkage was tested on the 3rd, 7th, 14th and 28th days. The drying shrinkage test standard is the cement mortar drying shrinkage test method GB / T 751-2007. The test results are shown in Table 5.

[0080] Table 5 Compressive strength and drying shrinkage test results

[0081] After curing for 28 days, the fire resistance of each group of ECC fireproof repair materials was tested: the ECC fireproof repair materials and concrete after curing for 28 days were calcined at 400℃, 600℃ and 800℃ respectively. Figure 1 , Figure 2 or Figure 3As shown in the figure, the failure morphology of the specimens at 400℃, 600℃ and 800℃ respectively. The left part of each figure is ECC and the right part is the concrete matrix. It can be seen that the concrete on the right has large cracks and damage, while the ECC on the left shows stronger fire resistance at 400℃~800℃ compared with ordinary concrete, with only slight cracks on the surface.

Claims

1. An ECC fireproof repair material, characterized in that: The raw materials of the ECC fireproof repair material include inorganic gel material, alkali activator, PVA fiber and water.

2. The ECC fireproof repair material according to claim 1, characterized in that: The mass ratio of the water to the inorganic gel material is 0.4-0.6:

1.

3. The ECC fireproof repair material according to claim 1, characterized in that: The mass ratio of the alkali activator to the inorganic gel material is 0.15-0.2:

1.

4. The ECC fireproof repair material according to claim 1, characterized in that: The inorganic gel material includes one or more of mineral powder, river sand or cement.

5. The ECC fireproof repair material according to claim 1, characterized in that: The inorganic gel material includes mineral powder and river sand, and the mass ratio of the mineral powder to the river sand is 1.2-1.3:

1.

6. The ECC fireproof repair material according to claim 1, characterized in that: The alkali activator includes a silicate alkali activator and an alkali hydroxide activator.

7. The ECC fireproof repair material according to claim 6, characterized in that: The silicate alkali activator includes sodium silicate and / or potassium silicate, and the alkaline hydroxide activator includes sodium hydroxide and / or potassium hydroxide.

8. The ECC fireproof repair material according to claim 1, characterized in that: The mass percentage of the PVA fiber is 1.5-2.5%.

9. A method for preparing the ECC fireproof repair material according to any one of claims 1 to 8, characterized in that: The preparation method comprises: First, a silicate alkali activator is fully mixed with water, and then an alkaline hydroxide activator is added and stirred until it is completely dissolved, and then allowed to stand until it becomes colorless and transparent, thereby obtaining an alkali activator; The inorganic gel material and PVA fiber are fully mixed and then an alkali activator is slowly added to obtain the ECC fireproof repair material.

10. Application of ECC fireproof repair material in concrete repair.

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