Basalt fiber reinforced concrete

Abstract

This invention relates to a basalt fiber reinforced concrete, wherein the water-to-cement ratio of the cement paste is between 0.3 and 0.5, accounting for 18% of the volume per cubic meter; the proportion of coarse and fine aggregates is between 65 and 75% of the volume per cubic meter; basalt fiber accounts for between 0.2 and 1.00% of the volume per cubic meter; and chemical admixtures for concrete account for 0.5% of the volume per cubic meter, used only to adjust the workability of the basalt fiber reinforced concrete.

Description

Basalt Fiber Reinforced Concrete The present invention relates to a basalt fiber reinforced concrete, in particular to a basalt fiber reinforced concrete that enhances toughness and destructive energy by adding basalt fibers to normal weight concrete. In the prior art, the natural properties of hardened concrete have excellent compressive strength but no toughness. That is, concrete has the ability to bear a large weight without collapsing, but has the inherent defects of being不耐tensile and不耐bending moment. Even when steel bars are added for reinforcement to form reinforced concrete (RC), there will not be much improvement. Due to this nature of concrete, traditional concrete mix design methods also mostly conform to this property, emphasizing the performance of compressive strength first, and the toughness performances such as tensile strength and flexural strength are secondary. In the field of civil engineering, concrete with high toughness is generally classified as high-performance concrete (HPC) or ultra-high-performance concrete (UHPC), which are new types of construction materials emerging in the field of civil engineering in recent years. However, concrete with high toughness actually has very high application value, including significantly enhancing the earthquake resistance, crack resistance and durability of structures, extending the service life of structures, and improving operation efficiency and economic value, etc. Looking internationally, high-toughness concrete has currently been widely applied in infrastructure fields such as transportation engineering and water conservancy engineering, such as bridge engineering, dam engineering, tunnel engineering, viaduct engineering, high-speed railway engineering, retaining wall engineering, etc. For example, the latest research and management team of the Federal Highway Administration in the United States - the Pavement Overlay Project (TOPS) has specifically started to incorporate the toughness design of civil materials into the road design specifications for interstate highways or federal roads and some state highways. When including the toughness design concept in the road design of cement concrete materials, cement concrete materials can be used as the overlay rigid pavement on existing rigid or flexible pavements, and detailed consideration should be given to the toughness design according to whether the two layers are bonded. Especially in recent years, global warming has led to frequent extreme temperatures, extreme rainfall and earthquake events, which have brought many impacts and damages to various infrastructures, making the engineering designs of various projects, including infrastructure projects, highly demand the toughness performance of concrete. In view of this, the research and development of high-toughness concrete has become an urgent issue. Therefore, in view of the disadvantages existing in the prior art, after careful attempts and research by the inventor, and with the spirit of perseverance, the present invention of "basalt fiber reinforced concrete" has finally been conceived, which can overcome the above disadvantages. The following is a brief description of the present invention. The present invention relates to a basalt fiber-reinforced concrete, and in particular to a basalt fiber-reinforced concrete that enhances toughness and fracture energy by adding basalt fibers to normal-weight concrete. Accordingly, the present invention relates to a basalt fiber-reinforced concrete, wherein the water-cement ratio of the cement paste is between 0.3 and 0.5, accounting for 18% of each cubic volume; the ratio of coarse and fine aggregates accounts for between 65-75% of each cubic volume; the basalt fibers account for between 0.2-1.00% of each cubic volume; and the chemical admixtures for concrete account for 0.5% of each cubic volume, only used to adjust the workability of the basalt fiber-reinforced concrete. Preferably, the water-cement ratio is selected from one of 0.30, 0.32, 0.35, 0.38, 0.40, 0.42, 0.44, 0.45, 0.46 and 0.50. Preferably, the volume percentage of the basalt fibers is selected from one of 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% and 1.0%. Preferably, the basalt fiber reinforcement comprises one of basalt fibers, unsaturated polyester, epoxy resin, vinyl resin, filler, curing agent and combinations thereof. Preferably, the basalt fibers are made by combining basalt fibers as the main material with polymer materials and then through a pultrusion process. Preferably, the basalt fiber reinforcement has a length between 3 and 14 mm. Preferably, after 28 days of curing in lime water, the basalt fiber-reinforced concrete has a compressive strength greater than 250 kgf / cm 2 (3,500 psi) and a fracture energy density greater than 250 J / m 3 and has better toughness. The above invention content aims to provide a simplified summary of the present disclosure to enable readers to have a basic understanding of the present disclosure. This invention content does not disclose the complete description of the present invention, and its intention is not to point out the important / critical elements of the embodiments of the present invention or to define the scope of the present invention. Figure 1 shows a graph of the relationship between the compressive strength of the concrete with added basalt fibers and the curing days. Figures 2 and 3 show actual images of the test configuration of the disk splitting test selected for testing the basalt fiber-reinforced concrete of the present invention; Figure 4 shows an actual image of the surface crack development of the basalt fiber-reinforced concrete with added basalt fibers; and FIG. 5 shows the actual image of providing the stiffening ability in the surface cracks by basalt fibers. The present invention will be fully understood from the following embodiments, so that those skilled in the art can implement it accordingly. However, the implementation of the present invention is not limited to the following embodiments; the drawings of the present invention do not include the limitations of size, dimension and scale, and the size, dimension and scale in the actual implementation of the present invention cannot be limited by the drawings of the present invention. The term "preferred" herein is non-exclusive and should be understood as "preferably but not limited to". Any step described or recited in any specification or claim can be executed in any order, not limited to the order described in the claim. The scope of the present invention should be determined only by the appended claims and their equivalents, and should not be determined by the embodiments of the implementation examples; when the term "comprising" and its variations appear in the specification and claims, it is an open-ended term and does not have a restrictive meaning, and does not exclude other features or steps. The research and development of high-toughness concrete has been an important topic. The present invention proposes to add basalt fibers as a stiffening material in the cement paste, and after hardening, it forms basalt fiber reinforced concrete, and proposes a special addition amount of basalt fiber bars, and the toughness design performance of the concrete structure after adding basalt fiber bars. The performance of the toughness strength is tested by selecting the disk splitting test to evaluate the fracture energy. The present invention proposes a kind of basalt fiber or basalt fiber reinforced bars, which takes basalt fiber as the main material, and after further combining with polymer materials, such as but not limited to: synthetic resin, unsaturated polyester, epoxy resin or vinyl resin, etc., fillers and curing agents and other polymer material matrices, and then through the pultrusion process to produce a new composite material. After measurement, the basalt fiber reinforced bars proposed by the present invention have the following physical properties. The density of the basalt fiber reinforced bars is between 1.9 and 2.1 g / cm 3 3, which is only about 1 / 4 of that of steel bars (the density of steel bars is 7.8-7.9). The tensile strength of the basalt fiber reinforced bars is about 2-3 times that of steel bars. The thermal expansion coefficient of the basalt fiber reinforced bars is similar to that of concrete, which can ensure the synchronous deformation of the basalt fiber reinforced bars and concrete. The basalt fiber reinforcement is a composite material made of non-metallic materials, so it is a non-rusting electrical insulator, non-magnetic, and has extremely high acid and alkali resistance. It has a relatively high tolerance to the water concentration in cement mortar and the penetration and diffusion of carbon dioxide, which can prevent the corrosion of concrete structures in harsh environments, thereby improving the durability of buildings. Example 1 (A) Composition material formula: (1) Cement: It is preferably Portland Type I / II cement (ASTM C150 Type I / II) because Type I and Type II Portland cements are widely used cements in concrete engineering and are suitable for general engineering and construction. (2) Coarse and fine aggregates: It is preferably to select six-point stone, three-point stone and fine sand as coarse and fine aggregates. (3) Basalt fiber: It is preferably to select basalt fiber reinforcement materials with lengths between 3 and 14 mm, which can be regarded as replacing part of the fine aggregates. (4) Chemical admixture: It is preferably to select an air-entraining agent that meets the requirements of ASTM C260 specifications, and select a water-reducing retarder as a superplasticizer to meet the requirements of ASTM C494 Type G. Chemical admixtures for concrete refer to chemical aids added before or during the mixing of concrete, except for cement paste, aggregates and basalt fiber reinforcements, to adjust and change the properties of fresh concrete or hardened concrete, including the workability of fresh concrete, setting time and hardening characteristics, etc. The purpose of adding a small amount of chemical admixtures is only to improve the mixing efficiency and workability. Generally, it is considered that the addition of chemical admixtures cannot enhance the toughness of concrete. (B) Mix ratio, mixing, specimen production, and toughness design performance evaluation of cement paste: (1) Cement slurry: It preferably has a water-cement ratio (w / c) between 0.15 and 0.75. (2) Mix ratio of cement slurry: It is preferably designed with "low-slurry volume" normal-weight concrete, and the water-cement ratio is preferably controlled at about 0.5. Six-point stone, three-point stone and fine sand are mixed in different proportions, and an air-entraining agent and a superplasticizer are added to increase workability. The mix ratio of "low-slurry volume" refers to the rigid pavement working mix ratio approved by the State Department of Transportation of the United States. The design concept is to minimize the cement consumption and improve the interlocking ability between aggregates, while the mix ratio of "high-slurry volume" is the common ratio of cement concrete aggregates and cement in Taiwan. (3) Add basalt fiber reinforcement to replace part of the fine aggregates at a volume percentage of 0, 0.5, 1.0, 1.5%. (4) After mixing is completed, immediately add the cement slurry in layers to specimens molds with diameters of 100 mm (4 inches) and 150 mm (6 inches), and vibrate on a vibrating table to produce hardened concrete specimens. (C) The properties of fresh concrete include slump, unit weight, air content, and fresh concrete temperature, etc. The properties are as follows: For the slump of the low-slurry ratio mix, regardless of the fiber addition amount, the slump is nearly zero; for the slump of the high-slurry ratio mix, it is generally distributed between 0 - 10 cm; in terms of unit weight, the unit weight is distributed at 2400 kgf / cm 2 ; and the mixing temperature did not increase significantly due to the addition of basalt fibers. (1) Concrete curing time: Figure 1 shows the relationship between the compressive strength of concrete with added basalt fibers and the curing days. Demold after 24 hours of pouring, immediately place it in saturated lime water for curing, and when the hydration age arrives, take it out for various relevant tests. The compressive strength of the concrete with added basalt fibers is as shown in Figure 1. At the hydration age of 28 days, the compressive strength of the hardened basalt fiber concrete is distributed between 300 - 380 kgf / cm 2 (4266 - 5404 psi). Example 2 In this example, it is preferably to use basalt fibers with lengths of 12 mm and 14 mm for reinforcement, and add them to the normal-weight cement slurry with a water-cement ratio of 0.45 or 0.60 at a ratio of 2 or 4 kg per cubic meter. After hardening to form a reinforced concrete structure, it can be known through measurement that the reinforced concrete structure with added basalt fiber reinforcement significantly increases the flexural strength by 9 - 14%, the fracture energy by 126 - 140%, and the abrasion resistance by 2 - 18%. However, for the reinforced concrete structure with more than 0.5% basalt fiber added, its compressive strength will decrease by about 8 - 18%. Example 3 In this example, it is preferably to use basalt fiber reinforcements with volume percentages of 0, 0.5, 1.0, 1.5, and 2.0-% and add them to the cement slurry with a water-cement ratio of 0.45. The mixing method of the cement slurry is to dry-mix the coarse and fine aggregates for 1.5 minutes first, then continue to dry-mix for 1 minute after adding Portland cement, and then stir the basalt fibers and mixing water together. After hardening to form a reinforced concrete structure, it can be known through measurement that for the reinforced concrete structure with added basalt fiber reinforcement, its splitting tensile strength increases up to 14% at the fiber addition ratio of 2%, the flexural strength increases by 15 - 75% in the fiber addition ratio range of 0.5 - 2%, the fracture energy increases by 220% at the fiber addition amount of 2%, but the compressive strength of the reinforced concrete structure will decrease by about 3%. Example 4 In this example, basalt fiber stiffeners with volume percentages of 0.10, 0.15, and 0.20% are preferably added to high-performance cement paste with a water-cement ratio of 0.22. After hardening to form a stiffened high-performance concrete structure, it can be measured that for the stiffened high-performance concrete structure with basalt fiber stiffeners added, the mechanical properties including flexural and splitting strengths increase by 1.1 - 24.5% and 21.9 - 44.5% respectively as the fiber addition amount increases, while the compressive strength of the stiffened concrete structure remains unchanged. Example 5 In this example, basalt fibers with lengths between 6 mm and 12 mm are preferably used for stiffening and added to normal-weight concrete at volume percentages of 0, 0.1, 0.2, 0.3, 0.4, and 0.5%. After hardening to form a stiffened concrete structure, it can be measured that the compressive strength is the highest when the addition amount of 6 mm long additive is 0.3% basalt fiber. However, using 12 mm and high addition amounts of basalt fiber may lead to a decrease in compressive strength due to uneven mixing and dispersion of the fibers. In terms of the splitting test, the splitting strength shows a downward trend when the basalt fiber addition amount is 0.5% in the mixing ratio. However, in the flexural test, regardless of the fiber length, the highest test value can be achieved. Figures 2 and 3 disclose the actual images of the test configuration for the disk splitting test used to test basalt fiber-reinforced concrete in the present invention. In the field of civil engineering materials, for the evaluation index of the toughness of civil engineering materials, the disk splitting test that can display the fracture energy is generally used for testing. Therefore, the present invention also selects the disk splitting test to test the toughness performance such as the fracture energy, transverse strain, and tensile strength of basalt fiber-reinforced concrete. In the disk splitting test, the present invention preferably selects a basalt fiber-reinforced concrete disk specimen with a diameter of 150 mm and a thickness of 38 mm, and its test configuration is as shown in Figures 1 and 2. While conducting the disk splitting test, the transverse strain is measured synchronously on the surface of the disk section, and the indirect tensile stress-strain diagram is plotted to evaluate the fracture energy. Figure 4 discloses the actual image of the surface crack development of basalt fiber-reinforced concrete with basalt fibers added; Figure 5 discloses the actual image of the basalt fibers providing stiffening ability in the surface cracks. The actual images of the surface crack development of the basalt fiber-reinforced concrete disk specimen after being split are as disclosed in Figures 4 and 5, and the basalt fibers show a good tensile resistance effect, enhancing the toughness of the disk specimen. The present invention proposes to add basalt fiber stiffeners that are not easily corroded to concrete materials as stiffening materials, which can improve the engineering mechanical properties and ductility design performance of the stiffened concrete structure, and can further improve the performance of the stiffened concrete structure, especially the seismic resistance, crack resistance, impact resistance and durability performance. The basalt fiber-reinforced concrete material proposed by the present invention can provide fields that require impact resistance, such as bus lanes, expansion joints, sidewalks, heavy traffic areas, building floors, etc. It can also be used as non-structural cement concrete products, including precast cement floor tiles, interlocking bricks, permeable bricks, and curb stones, etc., to improve their durability. For the basalt fiber-reinforced concrete proposed by the present invention, due to the addition of basalt fiber stiffeners, the restraint force provided by the basalt fiber stiffeners can improve the structure capacity, reduce the crack width, maintain the efficiency of longitudinal and transverse stress transfer, and improve the life cycle of the overall paved road surface and other characteristics. The above embodiments of the present invention can be combined or replaced with each other arbitrarily, thereby deriving more embodiments, but all are within the scope of protection of the present invention. Further, more embodiments of the present invention are provided as follows: Embodiment 1: A kind of basalt fiber-reinforced concrete, in which the water-cement ratio of the cement paste, that is, the water-cement ratio, is between 0.3 and 0.5, accounting for 18% of each cubic volume; the ratio of coarse and fine aggregates accounts for between 65-75% of each cubic volume; the basalt fiber accounts for between 0.2-1.00% of each cubic volume; and the chemical admixture for concrete accounts for 0.5% of each cubic volume, only used to adjust the workability of the basalt fiber-reinforced concrete. Embodiment 2: The basalt fiber-reinforced concrete as described in Embodiment 1, wherein the cement paste comprises Portland cement, Type I Portland cement, Type II Portland cement, Type III Portland cement, Type IV Portland cement, Type V Portland cement, air-entraining Portland cement, Type I air-entraining Portland cement, Type II air-entraining Portland cement, Type III air-entraining Portland cement, slag cement, fly ash cement, pozzolanic cement, masonry cement, expansive cement, waterproof cement, oil well cement, white cement, magnesia cement, Japanese cement and one of their combinations. Embodiment 3: The basalt fiber-reinforced concrete as described in Embodiment 1, wherein the water-cement ratio is selected from one of 0.30, 0.32, 0.35, 0.38, 0.40, 0.42, 0.44, 0.45, 0.46 and 0.50. Embodiment 4: The basalt fiber-reinforced concrete as described in Embodiment 1, wherein the volume percentage of the aggregate is preferably calculated with reference to the mix design method of the American Concrete Institute (ACI). Example 5: The basalt fiber-reinforced concrete as described in Example 1, wherein the fiber volume percentage is selected from one of 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, and 1.0%. Example 6: The basalt fiber-reinforced concrete as described in Example 1, wherein the chemical admixture for the concrete is selected from one of superplasticizer, air-entraining agent, water reducer, accelerating agent, retarding agent, early strength agent, water reducing and retarding agent, water reducing and early strength agent, high-performance water reducer, high-performance water reducing and retarding agent, plasticizer, plasticizing and retarding agent, pigment, corrosion inhibitor, dry shrinkage inhibitor, antifreeze agent, pumping aid, flowing concrete admixture, special-purpose admixture, and combinations thereof. Example 7: The basalt fiber-reinforced concrete as described in Example 1, wherein the basalt fiber-reinforcing bar comprises one of basalt fiber, unsaturated polyester, epoxy resin, vinyl resin, filler, curing agent, and combinations thereof. Example 8: The basalt fiber-reinforced concrete as described in Example 1, wherein the basalt fiber reinforcement is made by using basalt fiber as the main material, combining it with a polymer material, and then through a pultrusion process. Example 9: The basalt fiber-reinforced concrete as described in Example 1, wherein the basalt fiber reinforcement has a length between 3 and 14 mm. Example 10: The basalt fiber-reinforced concrete as described in Example 1. After 28 days of curing in lime water, the basalt fiber-reinforced concrete has a compressive strength greater than 250 kgf / cm 2 (3,500 psi) or more and a fracture energy density greater than 250 J / m 3 and has better toughness. Example 11: A basalt fiber-reinforced concrete, comprising: cement paste having a water-cement ratio between 0.3 and 0.5 and a paste volume percentage between 15 - 25%; aggregate having an aggregate volume percentage between 65 - 75%; basalt fiber-reinforcing bar having a fiber volume percentage between 0.2 - 1.00%; and chemical admixture for concrete for adjusting the properties of the basalt fiber-reinforced concrete. Example 12: The basalt fiber-reinforced concrete as described in Example 11, wherein the cement paste comprises one of Portland cement, Type I Portland cement, Type II Portland cement, Type III Portland cement, Type IV Portland cement, Type V Portland cement, air-entraining Portland cement, Type I air-entraining Portland cement, Type II air-entraining Portland cement, Type III air-entraining Portland cement, slag cement, fly ash cement, pozzolanic cement, masonry cement, expansive cement, waterproof cement, oil well cement, white cement, magnesia cement, Japanese cement, and combinations thereof. Example 13: The basalt fiber-reinforced concrete as described in Example 11, wherein the water-cement ratio is selected from one of 0.30, 0.32, 0.35, 0.38, 0.40, 0.42, 0.44, 0.45, 0.46, and 0.50. Example 14: The basalt fiber-reinforced concrete as described in Example 11, wherein the aggregate volume percentage is calculated according to the mix design method of the American Concrete Institute (ACI). Example 15: The basalt fiber-reinforced concrete as described in Example 11, wherein the fiber volume percentage is selected from one of 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, and 1.0%. Example 16: The basalt fiber-reinforced concrete as described in Example 11, wherein the chemical admixtures for concrete are selected from one of superplasticizers, air-entraining agents, water-reducing agents, accelerating agents, retarding agents, early-strength agents, water-reducing and retarding agents, water-reducing and early-strength agents, high-performance water-reducing agents, high-performance water-reducing and retarding agents, plasticizers, plasticizing and retarding agents, pigments, corrosion inhibitors, dry shrinkage inhibitors, antifreeze agents, pumping aids, flowing concrete admixtures, special-purpose admixtures, and combinations thereof. Example 17: The basalt fiber-reinforced concrete as described in Example 11, wherein the basalt fiber-reinforced bars comprise one of basalt fibers, unsaturated polyester, epoxy resin, vinyl resin, fillers, curing agents, and combinations thereof. Example 18: The basalt fiber-reinforced concrete as described in Example 11, wherein the basalt fiber-reinforced bars are made by using basalt fibers as the main material, combining with polymer materials, and then through the pultrusion process. Example 19: The basalt fiber-reinforced concrete as described in Example 11, wherein the basalt fiber-reinforced bars have a length between 3 and 14 mm. Example 20: The basalt fiber-reinforced concrete as described in Example 11, wherein the basalt fiber-reinforced concrete has a compressive strength greater than 250 kgf / cm2 (3,500 psi) and a fracture energy density greater than 250 J / m3. The embodiments of the present invention can be arbitrarily combined or replaced with each other, thereby deriving more implementation aspects, but all are within the scope of protection of the present invention. The definition of the protection scope of the present invention shall be subject to what is recorded in the patent application scope of the present invention.

Claims

1. A basalt fiber reinforced concrete comprising: a cement paste having a water-cement ratio between 0.3 and 0.5 and a paste volume percentage between 15 and 25%; an aggregate having a aggregate volume percentage between 65 and 75%; a basalt fiber reinforcing bar having a fiber volume percentage between 0.2 and 0.4%; and a concrete chemical admixture for adjusting the properties of the basalt fiber reinforced concrete, wherein the basalt fiber reinforced concrete has a compressive strength greater than 250 kgf / cm² (3,500 psi) and a breaking energy density greater than 250 J / m³.

2. The basalt fiber reinforced concrete as described in claim 1, wherein the cement slurry comprises one of the following: a first type Portland cement, a second type Portland cement, a third type Portland cement, a fourth type Portland cement, a fifth type Portland cement, a first type gas-transporting Portland cement, a second type gas-transporting Portland cement, a third type gas-transporting Portland cement, a slag cement, a fly ash cement, a volcanic ash cement, a masonry cement, an expansive cement, a waterproof cement, an oil well cement, a white cement, a magnesium oxychloride cement, a Japanese cement, or a combination thereof.

3. The basalt fiber reinforced concrete as described in claim 1, wherein the aggregate volume percentage is calculated in accordance with the American Concrete Institute (ACI) mix design method.

4. The basalt fiber reinforced concrete as described in claim 1, wherein the chemical admixture used in the concrete is selected from one of a plasticizer, an air-transfer agent, a water-reducing agent, an accelerator, a retarder, an early-strength agent, a water-reducing retarder, a water-reducing early-strength agent, a high-performance water-reducing agent, a high-performance water-reducing retarder, a plasticizer, a plasticizer and retarder, a pigment, a corrosion inhibitor, a drying shrinkage inhibitor, an antifreeze agent, a pump aid, a fluid concrete admixture, a special-purpose admixture, and combinations thereof.

5. The basalt fiber reinforced concrete as described in claim 1, wherein the basalt fiber reinforcing bar comprises one of a basalt fiber, an unsaturated polyester, an epoxy resin, a vinyl ester resin, a filler, a curing agent, and combinations thereof.

6. The basalt fiber reinforced concrete as described in claim 1, wherein the basalt fiber reinforcing bar is made by combining basalt fiber as the main material with a polymer material and then producing it through a pultrusion molding process.

7. Basalt fiber reinforced concrete as described in claim 1, wherein the basalt fiber reinforcing bars have a length between 3 and 14 mm.

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