A high-strength composite fiber expansion crack-resistant agent reinforced concrete and its preparation method and application

Abstract

The present invention belongs to the technical field of concrete, and specifically relates to a high-strength composite fiber expansion crack-resistant agent reinforced concrete, its preparation method and application. The concrete comprises the following components in parts by weight: 400-450 parts of sulfoaluminate cement, 200-250 parts of fly ash, 600-650 parts of sand, 900-950 parts of crushed stone, 10-15 parts of expansion agent, 3-7 parts of water reducing agent, 1-2 parts of defoaming agent, 200-250 parts of water, 6-10 parts of sisal fiber, 6-10 parts of flat glass fiber, and 2-4 parts of whiskers. The composite fiber expansion crack-resistant agent of the present invention can improve the crack resistance of concrete from both physical and chemical aspects, providing double protection for concrete. On the one hand, a large number of organic and inorganic fibers play a role in micro reinforcement and network support, inhibiting the cracking process of concrete; on the other hand, the expansion component reacts with the hydration products of cement and generates moderate expansion, which can prevent the shrinkage cracking of concrete, improve the crack resistance of concrete, and increase the compressive and flexural strengths of concrete.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete, and particularly relates to a high-strength composite fiber expansion crack-resistant agent enhanced concrete, its preparation method and application. Background Art

[0002] Concrete materials have the characteristics of wide raw material sources, relatively high compressive strength, good volume stability, easy construction and on-site shaping, and low cost. Due to its good plasticity and relatively reliable durability, it is still the most widely used and largest-consumed building material in the world. The application of concrete can be traced back to the road construction in ancient Rome. Since the advent of Portland cement in 1824, the application of concrete has entered a new stage. In the past nearly 200 years, the research on concrete has never stopped. The forms of concrete structures have become diversified, and the design theory of concrete structures has become increasingly mature.

[0003] In the past, it was generally believed that concrete was a material prepared by experience, and the selection of raw materials, the preparation process and the construction application were all relatively simple. However, since the early 1980s, the concrete technology has developed greatly, and the concrete strength has been greatly improved. The concrete technology has entered the high-tech era, which is mainly manifested in two aspects: materials and technology. By using high-efficiency water-reducing agents to reduce the water-cement ratio of concrete, using silica fume or fillers to fill the voids between cement particles, adopting new types of cement, and applying a certain pressure, high-performance concrete can be achieved.

[0004] Although people have introduced expansive agents and steel bars into the concrete structure in later development, to a certain extent, overcoming the defects of concrete as a brittle material, steel bars have problems such as being prone to deformation and corrosion, and there are also defects in difficult reinforcement in some complex or lightweight structures. Therefore, "ribs", that is, fibers, which are numerous, evenly distributed, and short, are incorporated into the concrete and have attracted more and more researchers' attention. Fiber-reinforced concrete has a research history of many years. It mainly improves the compressive strength of concrete and improves the later toughness by enhancing the bridging ability of fibers. Since then, new types of fibers have been applied to cement-based materials, and more types and characteristics of fiber-reinforced cement-based composites have been designed through changes in matrix materials; however, as a material with a multi-phase and multi-scale structure, the incorporation of a single fiber often makes it difficult to improve the performance of cement-based materials at different levels; and the performance differences of different types of fibers incorporated are relatively large, such as inorganic fibers with excellent anti-cracking and shrinkage-reducing effects but general toughening effects, and organic fibers with limited anti-cracking and shrinkage-reducing performance but obvious toughening effects. Therefore, hybrid fiber cement-based composites incorporating two or more different sizes, different moduli, and different performance characteristics are proposed. Due to differences in engineering practices, there are also different requirements for the performance and use characteristics of materials. With a wide variety of fiber types and diverse proportioning combinations, it is of great significance to select appropriate types and dosages among numerous fibers and apply fiber cement-based composites in combination with engineering practices. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a high-strength composite fiber expansive crack-resistant agent-reinforced concrete, its preparation method and application. An expansive agent and appropriate organic and inorganic fibers are added to sulfoaluminate concrete, and components such as fly ash and water-reducing agent are combined to improve the shrinkage performance of the concrete and increase the compressive and flexural strengths of the concrete.

[0006] The present invention provides a high-strength composite fiber expansive crack-resistant agent-reinforced concrete, which comprises the following components in parts by weight: 400 - 450 parts of sulfoaluminate cement, 200 - 250 parts of fly ash, 600 - 650 parts of sand, 900 - 950 parts of crushed stone, 10 - 15 parts of expansive agent, 3 - 7 parts of water-reducing agent, 1 - 2 parts of defoaming agent, 200 - 250 parts of water, 6 - 10 parts of sisal fiber, 6 - 10 parts of flat glass fiber, 2 - 4 parts of whiskers; the length of the sisal fiber is 5 - 13 mm; the diameter is 0.1 - 0.3 mm; the ratio of the major axis to the minor axis of the flat glass fiber is 3.0 - 5.0.

[0007] Sulphoaluminate cement has a fast setting speed, high early strength, excellent frost and impermeability resistance, and higher corrosion resistance than Portland cement. The cement stone structure is relatively dense, and its impermeability is 2-3 times that of Portland cement concrete of the same grade. It is mostly used in chemical industries such as high temperature and sewage treatment. However, sulphoaluminate cement itself has a fast setting time, concentrated hydration heat, and a reverse shrinkage of later strength, which limits its application scope.

[0008] In the present invention, the fineness modulus of the sand is 2.5-2.7, and the apparent density is 2500-2700 kg / m 3 ; the crushed stone has a continuous gradation with a particle size of 5-10 mm. Fly ash is the fine ash collected from the flue gas after coal combustion and is an industrial solid waste. Incorporating fly ash into cement not only improves the performance of the cement, but also reduces the environmental pollution caused by fly ash and the environmental pollution of concrete. Fly ash can reduce the shrinkage phenomenon, but the incorporation of fly ash can reduce the early strength of the concrete, which increases the possibility of early cracking of the concrete. To solve this problem, the present invention improves the self-compacting performance of the concrete of the structure by reasonably adding an expansion agent and a crack-resistant agent composed of various fibers. By adjusting the concrete mix ratio, the crack-resistant performance of the concrete is improved from the material source, effectively preventing the shrinkage and cracking of the concrete.

[0009] Sisal fiber belongs to organic fiber, which has good compatibility with concrete and is conducive to uniform dispersion; moreover, the flexible sisal fiber can intersect with glass fiber, improving the dispersion performance of glass fiber and eliminating the process of modifying glass fiber; more importantly, sisal fiber has high wet strength, good processability, light weight, small creep shrinkage, and low price. At the same time, sisal fiber has good water absorption performance and can retain water, which can be used as the internal curing water source of the concrete.

[0010] Compared with ordinary round-section glass fiber, flat glass fiber not only has an increased surface area and enhanced bonding force with concrete, but also has better toughness, and its flat structure is conducive to forming an interactive network structure with sisal fiber. The cross-sectional shape of the flat glass fiber can be a flat gourd shape, an oval shape, etc., as long as it has a major axis of the maximum length passing through the center point and a minor axis of the minimum length passing through the center point. Considering from the perspective of the manufacturing process, the oval shape is the best. The ratio of the major axis to the minor axis of the flat glass fiber is 3.0-6.0. When the ratio of the major axis to the minor axis is less than 3.0, the effect of making the cross-section flat decreases, and glass fibers with a ratio of more than 6.0 are not only difficult to manufacture themselves, but also have poor mechanical properties and are at risk of easy fracture.

[0011] The addition of sisal fibers and flat glass fibers in concrete can intersect with each other to form a network structure, which has the effect of network support and inhibits the cracking process of concrete. To further improve the strengthening effect, the present invention introduces a small amount of whiskers with high strength and high toughness technical effects. The whiskers are relatively shorter in size than glass fibers and are more corrosion-resistant. The fine whiskers can effectively inhibit the generation and development of early drying shrinkage microcracks and segregation cracks in concrete, greatly reducing the shrinkage cracks of concrete, especially effectively inhibiting the generation of connected cracks. A large number of fibers evenly distributed in the concrete and adhered to each other play the role of "supporting" the aggregates, effectively reducing the bleeding on the concrete surface and the segregation of aggregates, thereby greatly reducing the content of harmful pores in the concrete.

[0012] Generally speaking, the composite fiber expansion crack-resistant agent of the present invention can improve the crack resistance of concrete from both physical and chemical aspects, providing double protection for concrete. On the one hand, a large number of organic and inorganic fibers produce the effects of fine reinforcement and network support, inhibiting the cracking process of concrete; on the other hand, the expansion component reacts with the hydration products of cement and generates appropriate expansion, which can prevent the concrete from shrinking and cracking. The expansion agent mainly acts during the hardening process of concrete, while the fibers mainly play a role in the plastic stage of concrete. The composite of the composite fiber expansion crack-resistant agent embodies the concept of "stage crack resistance and hierarchical crack resistance", and can achieve the purpose of full-process crack resistance. They make the most effective contributions to concrete from different levels, in different ways, and at different times. At the same time, relying on the uniform distribution of a huge number of fibers in the concrete, a uniform random support system is formed inside the concrete, thereby generating an effective secondary strengthening effect and helping to reduce the stress during the plastic shrinkage of the concrete. The energy of shrinkage is dispersed to tens of millions of fiber filaments with high tensile strength per cubic meter, thereby effectively enhancing the toughness of the concrete and inhibiting the generation and development of fine cracks. At the same time, the addition of countless fiber filaments can effectively prevent the segregation of aggregates, ensure the uniform bleeding property of the concrete in the early stage, and thus prevent the formation of settlement cracks.

[0013] Further, the fly ash is at least one of first-class fly ash and second-class fly ash.

[0014] Further, the expansion agent is at least one of magnesium oxide expansion agent and calcium sulfoaluminate expansion agent.

[0015] Further, the water reducing agent is at least one of polycarboxylate water reducing agent, melamine water reducing agent, and melamine formaldehyde water reducing agent.

[0016] Further, the defoaming agent is at least one of silicone defoaming agent and polyether defoaming agent.

[0017] Furthermore, the sisal fiber has a length of 7-10 mm and a diameter of 0.1-0.3 mm. When the sisal fiber is too short, it is not conducive to forming an interactive network structure with the glass fiber; when the fiber length is too long, it is easy to entangle during the mixing process, forming a structure similar to a ball of yarn, and it is impossible to form a randomly distributed network reinforcement system with the glass fiber and whiskers.

[0018] Furthermore, the flat glass fiber has a length of 1-5 mm, specifically, it can be a flat glass fiber with a major axis of 28 μm, a minor axis of 7 μm, and a fiber length of 3 mm.

[0019] Furthermore, the whiskers are one or more of potassium titanate whiskers, zinc oxide whiskers, calcium sulfate whiskers, aluminum borate whiskers, basic magnesium sulfate whiskers, and calcium carbonate whiskers; the whisker length is 50-200 μm, and the diameter is 1-5 μm.

[0020] The present invention also provides a method for preparing high-strength composite fiber expansion crack-resistant agent reinforced concrete, which includes the following steps:

[0021] (1) Mix the sulfoaluminate cement, fly ash, water, sisal fiber, flat glass fiber, and whiskers evenly to obtain a premix;

[0022] (2) Add the expansion agent, water reducer, and defoamer to the premix and mix evenly to obtain an intermediate mixture;

[0023] (3) Add sand and gravel to the intermediate mixture and mix evenly to prepare high-strength composite fiber expansion crack-resistant agent reinforced concrete.

[0024] The present invention also provides the application of high-strength composite fiber expansion crack-resistant agent reinforced concrete in the chemical industry field, which has excellent shrinkage performance and improves the compressive and flexural strengths of concrete.

[0025] Compared with the prior art, the present invention has the following technical advantages:

[0026] The addition of sisal fiber and flat glass fiber in the concrete can intersect with each other to form a network structure, which has the effect of network support and inhibits the cracking process of the concrete; the fine whiskers can effectively inhibit the generation and development of early dry shrinkage microcracks and segregation cracks in the concrete, greatly reducing the shrinkage cracks of the concrete, especially effectively inhibiting the generation of connected cracks. A large number of fibers evenly distributed in the concrete and adhered to each other play the role of "supporting" the aggregate, greatly reducing the content of harmful pores in the concrete.

[0027] The composite fiber expansion crack inhibitor can improve the crack resistance of concrete from both physical and chemical aspects, providing double protection for concrete. On the one hand, a large number of organic and inorganic fibers play the role of micro reinforcement and reticular support, inhibiting the cracking process of concrete; on the other hand, the expansion component reacts with the hydration products of cement and generates moderate expansion, which can prevent the shrinkage cracking of concrete and inhibit the generation and development of micro cracks. Specific embodiments

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0029] Unless otherwise specified, the types of raw materials in the examples and comparative examples are the same.

[0030] Example 1

[0031] A high-strength composite fiber expansion crack inhibitor reinforced concrete, comprising the following components in parts by weight: 400 parts of sulfoaluminate cement, 200 parts of first-class fly ash, 600 parts of sand, 900 parts of gravel, 10 parts of magnesium oxide expansion agent, 3 parts of polycarboxylate water reducer, 1 part of silicone defoamer, 200 parts of water, 6 parts of sisal fiber, 6 parts of flat glass fiber, 2 parts of whiskers; the sisal fiber has a length of 7 mm and a diameter of 0.2 mm; the flat glass fiber has a length-to-diameter ratio of 4.0, a major diameter of 28 μm, a minor diameter of 7 μm, and a fiber length of 3 mm; the whiskers are calcium sulfate whiskers, with a whisker length of 100 μm and a diameter of 3 μm.

[0032] Example 2

[0033] A high-strength composite fiber expansion crack inhibitor reinforced concrete, comprising the following components in parts by weight: 450 parts of sulfoaluminate cement, 250 parts of second-class fly ash, 650 parts of sand, 950 parts of gravel, 15 parts of calcium sulfoaluminate-based expansion agent, 7 parts of polycarboxylate water reducer, 2 parts of polyether defoamer, 250 parts of water, 10 parts of sisal fiber, 10 parts of flat glass fiber, 4 parts of whiskers; the sisal fiber has a length of 10 mm and a diameter of 0.2 mm; the flat glass fiber has a length-to-diameter ratio of 4.0, a major diameter of 28 μm, a minor diameter of 7 μm, and a fiber length of 3 mm; the whiskers are potassium titanate whiskers, with a whisker length of 60 μm and a diameter of 4 μm.

[0034] Example 3

[0035] A high-strength composite fiber expansion crack-resistant agent reinforced concrete, comprising the following components in parts by weight: 400 parts of sulfoaluminate cement, 250 parts of secondary fly ash, 650 parts of sand, 950 parts of gravel, 15 parts of calcium sulfoaluminate-based expansion agent, 7 parts of polycarboxylate water reducer, 1 part of silicone defoamer, 200 parts of water, 10 parts of sisal fiber, 10 parts of flat glass fiber, 2 parts of whiskers; the sisal fiber has a length of 9 mm and a diameter of 0.2 mm; the flat glass fiber has a major axis / minor axis ratio of 4.0, a major axis of 28 μm, a minor axis of 7 μm, and a fiber length of 3 mm; the whiskers are calcium carbonate whiskers with a whisker length of 80 μm and a diameter of 3 μm.

[0036] Example 4

[0037] A high-strength composite fiber expansion crack-resistant agent reinforced concrete, comprising the following components in parts by weight: 450 parts of sulfoaluminate cement, 200 parts of primary fly ash, 600 parts of sand, 900 parts of gravel, 10 parts of calcium sulfoaluminate-based expansion agent, 3 parts of polycarboxylate water reducer, 1 part of silicone defoamer, 250 parts of water, 6 parts of sisal fiber, 10 parts of flat glass fiber, 4 parts of whiskers; the sisal fiber has a length of 8 mm and a diameter of 0.2 mm; the flat glass fiber has a major axis / minor axis ratio of 4.0, a major axis of 28 μm, a minor axis of 7 μm, and a fiber length of 3 mm; the whiskers are calcium sulfate whiskers with a whisker length of 100 μm and a diameter of 3 μm.

[0038] Example 5

[0039] A high-strength composite fiber expansion crack-resistant agent reinforced concrete, comprising the following components in parts by weight: 420 parts of sulfoaluminate cement, 210 parts of primary fly ash, 620 parts of sand, 940 parts of gravel, 14 parts of calcium sulfoaluminate-based expansion agent, 6 parts of polycarboxylate water reducer, 1.4 parts of silicone defoamer, 242 parts of water, 9 parts of sisal fiber, 8 parts of flat glass fiber, 3 parts of whiskers; the sisal fiber has a length of 9 mm and a diameter of 0.2 mm; the flat glass fiber has a major axis / minor axis ratio of 4.0, a major axis of 28 μm, a minor axis of 7 μm, and a fiber length of 3 mm; the whiskers are calcium sulfate whiskers with a whisker length of 100 μm and a diameter of 3 μm.

[0040] Example 6

[0041] A high-strength composite fiber expansion crack-resistant agent reinforced concrete, comprising the following components in parts by weight: 440 parts of sulfoaluminate cement, 238 parts of secondary fly ash, 645 parts of sand, 920 parts of gravel, 11 parts of calcium sulfoaluminate-based expansion agent, 4 parts of polycarboxylate water reducer, 1 part of polyether defoamer, 220 parts of water, 7 parts of sisal fiber, 7 parts of flat glass fiber, 2 parts of whiskers; the sisal fiber has a length of 8 mm and a diameter of 0.2 mm; the flat glass fiber has a length-to-diameter ratio of 4.0, a major axis of 28 μm, a minor axis of 7 μm, and a fiber length of 3 mm; the whiskers are calcium sulfate whiskers, with a whisker length of 100 μm and a diameter of 3 μm.

[0042] Example 7

[0043] A high-strength composite fiber expansion crack-resistant agent reinforced concrete, comprising the following components in parts by weight: 420 parts of sulfoaluminate cement, 242 parts of primary fly ash, 615 parts of sand, 938 parts of gravel, 12 parts of calcium sulfoaluminate-based expansion agent, 6 parts of polycarboxylate water reducer, 1.4 parts of polyether defoamer, 222 parts of water, 7 parts of sisal fiber, 9 parts of flat glass fiber, 3 parts of whiskers; the sisal fiber has a length of 8 mm and a diameter of 0.2 mm; the flat glass fiber has a length-to-diameter ratio of 4.0, a major axis of 28 μm, a minor axis of 7 μm, and a fiber length of 3 mm; the whiskers are calcium sulfate whiskers, with a whisker length of 100 μm and a diameter of 3 μm.

[0044] Example 8

[0045] A high-strength composite fiber expansion crack-resistant agent reinforced concrete, comprising the following components in parts by weight: 425 parts of sulfoaluminate cement, 230 parts of primary fly ash, 630 parts of sand, 920 parts of gravel, 13 parts of calcium sulfoaluminate-based expansion agent, 5 parts of polycarboxylate water reducer, 1.5 parts of silicone defoamer, 230 parts of water, 8 parts of sisal fiber, 8 parts of flat glass fiber, 3 parts of whiskers; the sisal fiber has a length of 8 mm and a diameter of 0.2 mm; the flat glass fiber has a length-to-diameter ratio of 4.0, a major axis of 28 μm, a minor axis of 7 μm, and a fiber length of 3 mm; the whiskers are calcium sulfate whiskers, with a whisker length of 100 μm and a diameter of 3 μm.

[0046] Example 9

[0047] A high-strength composite fiber expansion crack-resistant agent-reinforced concrete, comprising the following components in parts by weight: 425 parts of sulfoaluminate cement, 230 parts of Class I fly ash, 630 parts of sand, 920 parts of crushed stone, 13 parts of calcium sulfoaluminate-based expansion agent, 5 parts of polycarboxylate water reducer, 1.5 parts of silicone defoamer, 230 parts of water, 8 parts of sisal fiber, 8 parts of flat glass fiber, 3 parts of whiskers; the sisal fiber has a length of 5 mm and a diameter of 0.2 mm; the flat glass fiber has a ratio of major axis / minor axis of 4.0, a major axis of 28 μm, a minor axis of 7 μm, and a fiber length of 3 mm; the whiskers are calcium sulfate whiskers with a length of 100 μm and a diameter of 3 μm.

[0048] Example 10

[0049] A high-strength composite fiber expansion crack-resistant agent-reinforced concrete, comprising the following components in parts by weight: 425 parts of sulfoaluminate cement, 230 parts of Class I fly ash, 630 parts of sand, 920 parts of crushed stone, 13 parts of calcium sulfoaluminate-based expansion agent, 5 parts of polycarboxylate water reducer, 1.5 parts of silicone defoamer, 230 parts of water, 8 parts of sisal fiber, 8 parts of flat glass fiber, 3 parts of whiskers; the sisal fiber has a length of 13 mm and a diameter of 0.2 mm; the flat glass fiber has a ratio of major axis / minor axis of 4.0, a major axis of 28 μm, a minor axis of 7 μm, and a fiber length of 3 mm; the whiskers are calcium sulfate whiskers with a length of 100 μm and a diameter of 3 μm.

[0050] Comparative Example 1

[0051] A high-strength composite fiber expansion crack-resistant agent-reinforced concrete, comprising the following components in parts by weight: 425 parts of sulfoaluminate cement, 230 parts of Class I fly ash, 630 parts of sand, 920 parts of crushed stone, 13 parts of calcium sulfoaluminate-based expansion agent, 5 parts of polycarboxylate water reducer, 1.5 parts of silicone defoamer, 230 parts of water, 8 parts of sisal fiber, 8 parts of round-section glass fiber, 3 parts of whiskers; the sisal fiber has a length of 8 mm and a diameter of 0.2 mm; the round-section glass fiber has a diameter of 10 μm and a fiber length of 3 mm; the whiskers are calcium sulfate whiskers with a length of 100 μm and a diameter of 3 μm.

[0052] Comparative Example 2

[0053] A high-strength composite fiber expansion crack-resistant agent-reinforced concrete, comprising the following components in parts by weight: 425 parts of sulfoaluminate cement, 230 parts of Class I fly ash, 630 parts of sand, 920 parts of crushed stone, 13 parts of calcium sulfoaluminate-based expansion agent, 5 parts of polycarboxylate water reducer, 1.5 parts of silicone defoamer, 230 parts of water, 13.8 parts of flat glass fiber, 5.2 parts of whiskers; the flat glass fiber has a ratio of major axis / minor axis of 4.0, a major axis of 28 μm, a minor axis of 7 μm, and a fiber length of 3 mm; the whiskers are calcium sulfate whiskers with a length of 100 μm and a diameter of 3 μm.

[0054] Comparative Example 3

[0055] A high-strength composite fiber expansion crack-resistant agent reinforced concrete, comprising the following components in parts by weight: 425 parts of sulfoaluminate cement, 230 parts of class I fly ash, 630 parts of sand, 920 parts of gravel, 13 parts of calcium sulfoaluminate-based expansion agent, 5 parts of polycarboxylate water reducer, 1.5 parts of organosilicon defoamer, 230 parts of water, 13.8 parts of sisal fiber, 5.2 parts of whiskers; the sisal fiber has a length of 8 mm and a diameter of 0.2 mm; the whiskers are calcium sulfate whiskers with a length of 100 μm and a diameter of 3 μm.

[0056] Comparative Example 4

[0057] A high-strength composite fiber expansion crack-resistant agent reinforced concrete, comprising the following components in parts by weight: 425 parts of sulfoaluminate cement, 230 parts of class I fly ash, 630 parts of sand, 920 parts of gravel, 13 parts of calcium sulfoaluminate-based expansion agent, 5 parts of polycarboxylate water reducer, 1.5 parts of organosilicon defoamer, 230 parts of water, 9.5 parts of sisal fiber, 9.5 parts of flat glass fiber; the sisal fiber has a length of 8 mm and a diameter of 0.2 mm; the flat glass fiber has a major axis / minor axis ratio of 4.0, a major axis of 28 μm, a minor axis of 7 μm, and a fiber length of 3 mm.

[0058] Comparative Example 5

[0059] A high-strength composite fiber expansion crack-resistant agent reinforced concrete, comprising the following components in parts by weight: 425 parts of sulfoaluminate cement, 230 parts of class I fly ash, 630 parts of sand, 920 parts of gravel, 13 parts of calcium sulfoaluminate-based expansion agent, 5 parts of polycarboxylate water reducer, 1.5 parts of organosilicon defoamer, 230 parts of water, 8 parts of sisal fiber, 14 parts of flat glass fiber, 3 parts of whiskers; the sisal fiber has a length of 8 mm and a diameter of 0.2 mm; the flat glass fiber has a major axis / minor axis ratio of 4.0, a major axis of 28 μm, a minor axis of 7 μm, and a fiber length of 3 mm; the whiskers are calcium sulfate whiskers with a length of 100 μm and a diameter of 3 μm.

[0060] Comparative Example 6

[0061] A high-strength composite fiber expansion crack-resistant agent reinforced concrete, comprising the following components in parts by weight: 425 parts of sulfoaluminate cement, 230 parts of class I fly ash, 630 parts of sand, 920 parts of gravel, 13 parts of calcium sulfoaluminate-based expansion agent, 5 parts of polycarboxylate water reducer, 1.5 parts of silicone defoamer, 230 parts of water, 8 parts of sisal fiber, 8 parts of flat glass fiber, 1 part of whisker; the sisal fiber has a length of 8 mm and a diameter of 0.2 mm; the flat glass fiber has a major axis / minor axis ratio of 4.0, a major axis of 28 μm, a minor axis of 7 μm, and a fiber length of 3 mm; the whisker is a calcium sulfate whisker with a whisker length of 100 μm and a diameter of 3 μm.

[0062] Comparative Example 7

[0063] A high-strength composite fiber expansion crack-resistant agent reinforced concrete, comprising the following components in parts by weight: 425 parts of sulfoaluminate cement, 230 parts of class I fly ash, 630 parts of sand, 920 parts of gravel, 13 parts of calcium sulfoaluminate-based expansion agent, 5 parts of polycarboxylate water reducer, 1.5 parts of silicone defoamer, 230 parts of water, 8 parts of sisal fiber, 8 parts of flat glass fiber, 7 parts of whisker; the sisal fiber has a length of 8 mm and a diameter of 0.2 mm; the flat glass fiber has a major axis / minor axis ratio of 4.0, a major axis of 28 μm, a minor axis of 7 μm, and a fiber length of 3 mm; the whisker is a calcium sulfate whisker with a whisker length of 100 μm and a diameter of 3 μm.

[0064] The raw material components in Examples 1-10 and Comparative Examples 1-7 were prepared into high-strength composite fiber expansion crack-resistant agent reinforced concrete according to the following preparation method, including the following steps:

[0065] (1) Mix the sulfoaluminate cement, fly ash, water, sisal fiber, flat glass fiber, and whisker evenly to obtain a premix.

[0066] (2) Add the expansion agent, water reducer, and defoamer to the premix and mix evenly to obtain an intermediate mixture.

[0067] (3) Add the sand and gravel to the intermediate mixture and mix evenly to prepare the high-strength composite fiber expansion crack-resistant agent reinforced concrete.

[0068] Refer to the existing standards to test the compressive strength, flexural strength, and drying shrinkage rate of the concrete. The results are shown in Tables 1-2:

[0069]

[0070]

[0071] As can be seen from Examples 1-10, the composite fiber expansion crack inhibitor of the present invention can improve the crack resistance of concrete from both physical and chemical aspects, providing double protection for concrete. On the one hand, a large number of organic and inorganic fibers play the roles of micro reinforcement and reticular support, inhibiting the cracking process of concrete; on the other hand, the expansion component reacts with the hydration products of cement and generates appropriate expansion, which can prevent concrete from shrinkage cracking, improve the shrinkage performance of concrete, and increase the compressive and flexural strengths of concrete. As can be seen from Example 8 and Comparative Examples 1-4, compared with ordinary round-section glass fibers, flat glass fibers have enhanced bonding force with concrete and better toughness, which is beneficial to forming an interactive network structure with sisal fibers. Among them, the rigid flat glass fibers and the flexible sisal fibers form a basic network framework, playing the role of "supporting" the aggregate, effectively reducing the bleeding on the concrete surface and the segregation of aggregates; while incorporating a certain amount of whisker microfibers can effectively inhibit the generation and development of early dry shrinkage microcracks and segregation cracks in concrete, greatly reducing the shrinkage cracks of concrete, especially effectively inhibiting the generation of connected cracks. It can be seen that sisal fibers, flat-section glass fibers, and whiskers play a synergistic strengthening role. Comparative Examples 5-7 show that it is necessary to control the dosages of sisal fibers, flat-section glass fibers, and whiskers: when the dosage of flat-section glass fibers or whiskers is too much, sedimentation and agglomeration are likely to occur, and the role of reticular support cannot be played; when the dosage of whiskers is too little, it cannot play the role of filling the space between sisal fibers and flat-section glass fibers.

Claims

1. A high-strength composite fiber expansion anti-cracking agent reinforced concrete, characterized in that: The invention is composed of the following components in parts by weight: 400-450 parts of sulphoaluminate cement, 200-250 parts of fly ash, 600-650 parts of sand, 900-950 parts of crushed stone, 10-15 parts of expansion agent, 3-7 parts of water reducing agent, 1-2 parts of defoaming agent, 200-250 parts of water, 6-10 parts of sisal fiber, 6-10 parts of flat glass fiber, and 2-4 parts of whisker; the sisal fiber has a length of 7-10 mm; a diameter of 0.1- 0.3mm; the major diameter / minor diameter ratio of the flat glass fiber is 3.0-5.0; the expander is at least one of a magnesium oxide expander and a calcium sulfoaluminate expander; the whisker is one or more of a potassium titanate whisker, a zinc oxide whisker, a calcium sulfate whisker, an aluminum borate whisker, a basic magnesium sulfate whisker, and a calcium carbonate whisker; the whisker length is 50-200μm, and the diameter is 1-5μm; the flat glass fiber length is 1-5mm.

2. A high-strength composite fiber expansion anti-cracking agent reinforced concrete as claimed in claim 1, characterized in that: The fly ash is at least one of primary fly ash and secondary fly ash.

3. A high-strength composite fiber expansion anti-cracking agent reinforced concrete as claimed in claim 1, characterized in that: The water reducer is at least one of a polycarboxylic acid water reducer, a melamine water reducer and a melamine water reducer.

4. The high-strength composite fiber expansion anti-cracking agent reinforced concrete according to claim 1, characterized in that: The defoamer is at least one of an organosilicon defoamer and a polyether defoamer.

5. A method for preparing high-strength composite fiber expansion anti-cracking agent reinforced concrete according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Sulphoaluminate cement, fly ash, water, sisal fiber, flat glass fiber and whisker are uniformly mixed to obtain a premix; (2) Add the expansion agent, water reducing agent and defoaming agent to the premix and mix them evenly to obtain the intermediate material; (3) Add sand and gravel to the intermediate material and mix them evenly to obtain high-strength composite fiber expansion anti-cracking agent reinforced concrete.

6. Application of the high-strength composite fiber expansion anti-cracking agent reinforced concrete as claimed in any one of claims 1 to 4 in the chemical industry.

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