Soil Pavement Composition Using Eco-friendly Fiber Reinforcement

Abstract

A soil paving composition containing an eco-friendly fiber reinforcement is disclosed, comprising a carbonate produced by reacting red mud with carbon dioxide, a major culprit of greenhouse gases, based on eco-friendly materials, and a fiber reinforcement made from recycled waste plastic. When used as a construction material, this composition can reduce carbon dioxide emissions, improve strength, and prevent cracking. The disclosed soil paving composition containing the eco-friendly fiber reinforcement may include a cement-free binder; carbonated red mud; an anti-efflorescence agent; fine aggregate; and water.

Description

Technology Field

[0001] The present invention relates to a soil paving material composition using an eco-friendly fiber reinforcement, and more specifically, to a soil paving material composition using an eco-friendly fiber reinforcement that is eco-friendly, reinforces the strength of the soil paving material, and prevents cracking. Background Technology

[0003] Recently, as average human life expectancy has increased, interest in health has been on the rise. Reflecting this trend, the construction of parks, bicycle paths, and walking trails is continuously increasing. Furthermore, there is a growing desire not only for personal health but also to transform the surrounding environment.

[0004] In other words, as part of efforts to transform the surrounding environment, there is growing interest in the use of earthen paving that can evoke aesthetic inspiration in natural environments, such as temples and cultural heritage sites, or in areas with unique cultural characteristics.

[0005] Meanwhile, soil paving can be constructed using a dry or wet method by mixing cement and local pigments with weathered granite soil, but since it is considerably more expensive than concrete, it can create a negative image if defects occur. In addition, conventional soil-concrete paving materials have low flexural and tensile strength when constructed dry, which can cause cracking when exposed to ultraviolet rays and moisture.

[0006] Furthermore, although the use of red mud, an industrial byproduct, is increasing recently as a means to reduce greenhouse gases and recycle waste plastics as an earthen paving material, a decrease in compressive strength is inevitable when red mud, which is highly alkaline, is utilized as a material for concrete structures.

[0007] Therefore, to address these issues, it is necessary not only to develop reinforcement technologies capable of improving the strength and durability of soil pavements, but also to develop technologies that neutralize highly alkaline red mud for use as a material in concrete structures.

[0008] In addition, research is actively underway to utilize stabilized red mud as a building material by applying mineral carbonation technology, which permanently fixes carbon dioxide—the main culprit of greenhouse gases—to red mud. Prior art literature

[0010] Registered Patent Publication 10-1439236 (Publication Date: September 12, 2014) The problem to be solved

[0012] The present invention was conceived in consideration of the points mentioned above, and aims to provide a soil paving composition containing an eco-friendly fiber reinforcement comprising a cement-free binder, carbonated red mud; an anti-efflorescence agent; fine aggregate; and water. The invention is based on an eco-friendly cement-free binder and includes carbonated red mud to reduce carbon dioxide, the main culprit of greenhouse gases, and a fiber reinforcement to improve strength. means of solving the problem

[0014] To achieve the above objective, the soil paving material composition containing an eco-friendly fiber reinforcement according to the present invention may comprise a cement-free binder; carbonated red mud; an anti-efflorescence agent; fine aggregate; and water.

[0015] The above soil paving material composition is characterized by containing a cement-free binder, carbonated red mud, an anti-efflorescence agent, fine aggregate, and water in a weight ratio of 1:0.8 to 1.2:0.01 to 0.1:3.0 to 3.6:0.5 to 1.

[0016] The above soil paving material composition is characterized by further including 1 to 5 wt% of fiber reinforcement based on the total wt%.

[0017] The above fiber reinforcement is characterized by being in the form of short fibers that are cut into a predetermined size after being coated with a silicone emulsion and dried, on at least one selected from polyester fibers or polyethylene terephthalate fibers made from recycled waste plastics.

[0018] The carbonated red mud is prepared by the following steps: a first step of preparing liquid red mud by mixing red mud sludge and water in a weight ratio of 1:10 to 1:2; a second step of preparing a mixture by mixing acid into the liquid red mud; a third step of separating the mixture into an extract and a precipitate by filtering the mixture; a fourth step of preparing a basic solution by adding NaOH to the extract; and a fifth step of injecting carbon dioxide into the basic solution to prepare and recover carbonates; wherein the solid content of the red mud sludge comprises 5 to 10 parts by weight per 100 parts by weight of a non-cemented binder.

[0019] The method is characterized by further including generating ultrasound to promote the mineral carbonation reaction after injecting the carbon dioxide in the above 5th step.

[0020] The above soil paving material composition is characterized by further including 3 to 8 wt% of an expansive agent relative to the total wt%.

[0021] The above soil paving material composition is characterized by further including at least one of a dispersant, an antifoaming agent, and a thickener in an amount of 1 to 5 parts by weight based on 100 parts by weight of the above cement-free binder.

[0022] The above carbonated red mud is characterized by containing 65 kg or more of carbon dioxide per ton.

[0023] The above soil paving material composition is characterized by satisfying (a) to (c) below.

[0024] (a) After 28 days of curing, compressive strength is 30 MPa or more and flexural strength is 5 MPa or more

[0025] (b) Compressive strength ratio (%) after freeze-thaw is 85% or higher

[0026] (c) Drying shrinkage rate of 0.05% or less Effects of the invention

[0028] The soil paving composition containing an eco-friendly fiber reinforcement according to the present invention is characterized by comprising a cement-free binder; carbonated red mud; an anti-efflorescence agent; fine aggregate; and water. By carbonating red mud sludge, an industrial byproduct, based on a cement-free binder, it is eco-friendly and improves the solubility rate of carbon dioxide, a major culprit of greenhouse gases. Furthermore, by containing a fiber reinforcement made from recycled waste plastic, it exhibits excellent strength and an improved drying shrinkage rate. Specific details for implementing the invention

[0030] All terms described in this specification have been selected based on currently widely used general terms in consideration of the functions of the present invention; however, these may vary depending on the intent, convention, or emergence of new technologies of those skilled in the art. Furthermore, if the inventor specifies any term in this invention, its meaning will be described in the description of the invention. Therefore, terms used in this invention should be interpreted not merely by their names, but based on their actual meanings and the overall content described in the description of the invention.

[0031] A soil paving material composition containing an eco-friendly fiber reinforcement according to an embodiment of the present invention will be described in detail.

[0032] The present invention provides a soil paving material composition containing an eco-friendly fiber reinforcement.

[0033] A soil paving material composition containing an eco-friendly fiber reinforcement according to an embodiment of the present invention may comprise a cement-free binder; carbonated red mud; an anti-efflorescence agent; fine aggregate; and water. The soil paving material composition may comprise the cement-free binder, carbonated red mud, anti-efflorescence agent, fine aggregate, and water in a weight ratio of 1:0.8 to 1.2:0.01 to 0.1:3.0 to 3.6:0.5 to 1.

[0034] The above cement-free binder is included in the soil paving material composition of the present invention. The above cement-free binder may selectively use at least one of fly ash, blast furnace slag, calcium carbonate, calcium hydroxide, etc.

[0035] The fineness of the above cement-free binder is 3,000 to 4,500 cm 2 / g, and the density may be 1.9 to 2.3 g / cm³. The main chemical composition of the cement-free binder comprises 95 to 97 wt% of SiO2, Fe2O3, Al2O3, CaO, and MgO based on the total wt%. Additionally, it may be preferable for the cement-free binder to contain at least 10 wt% of CaO and at least 30 wt% of SiO2 based on the total wt% for sufficient hydration reaction, and at least 2% of MgO to suppress abnormal expansion.

[0036] When the above CaO is applied to the soil paving material of the present invention, the porosity of the mixture is relatively large at approximately 5%, so it can serve as a filler to fill the pores at the interface and as an anti-splitting agent. In addition, the CaO, SiO2 components contained in the above cement-free binder can participate in the hydration reaction to improve adhesion strength.

[0037] The aforementioned fly ash is a byproduct generated when coal is used as a raw material in thermal power generation. Specifically, when coal is ground into powder and burned in facilities that use coal as fuel, such as thermal power plants, it remains as fine dust consisting of silicon oxide (SiO2) or aluminum oxide (AL2O3). Fly ash is the result of capturing this dust using a dust collector. The size of the fly ash particles is similar to that of cement particles. Mixing this fly ash into soil paving materials can be economical because it improves workability, lowers the heat of curing, and enhances long-term strength and watertightness. Therefore, adding fly ash to soil paving materials instead of expensive cement may slightly extend the curing time, but it can improve fluidity, increase long-term strength, reduce heat of hydration, suppress alkali-fine aggregate reactions, and enhance resistance to sulfates and watertightness.

[0038] In addition, the fineness of the above fly ash fine powder may be 3,000 to 4,500 cm2 / g and the density may be 1.9 to 2.3 g / cm3. The main chemical composition of the above fly ash is SiO2, Fe2O3, Al2O3, CaO, and MgO, comprising 95 to 97 wt% of the total chemical composition. Furthermore, among the main components of the above fly ash, having 10 wt% or more of CaO, 30 wt% or more of SiO2, and 2 wt% or less of MgO components for sufficient hydration reaction can help reduce the effect of drying shrinkage and improve long-term strength and durability through pozzolanic reaction.

[0039] The above-mentioned blast furnace slag is a byproduct formed during the pig iron production process of iron ore, where rocks included as impurities in the iron ore combine with lime. Depending on its application, the above-mentioned blast furnace slag can be classified into rapidly cooled blast furnace slag, slowly cooled blast furnace slag, and semi-rapidly cooled blast furnace slag. The above-mentioned rapidly cooled slag is molten slag generated during the production of pig iron at a steel mill, which is rapidly cooled with cooling water to form a glassy, ​​fine sand-like substance that can be used for blast furnace cement, fine aggregate for concrete, and concrete admixtures. The above-mentioned slowly cooled blast furnace slag is molten slag that is slowly removed from the blast furnace and cooled to solidify; it can be used for roads, fine aggregate for concrete, harbor materials, lime silicate fertilizers, etc. The above-mentioned semi-rapidly cooled blast furnace slag can be used for lightweight concrete fine aggregate, lightweight landfill material, thermal insulation material, etc. In the embodiments of the present invention, the slowly cooled blast furnace slag can be mainly selected. Therefore, in the present invention, "blast furnace slag" refers to slow-cooled blast furnace slag. The blast furnace slag, when incorporated into concrete or the like, possesses characteristics such as increased fluidity, reduced permeability, and a compressive strength that decreases initially but increases over time.

[0040] In addition, the fineness of the above-mentioned blast furnace slag fine powder may be 3,500 to 4,500 cm² / g, and the density may be 2.7 to 2.9 g / cm³. The main chemical composition of the above-mentioned blast furnace slag is SiO2, Fe2O3, Al2O3, CaO, and MgO, comprising 95 to 97 wt% of the total chemical composition. Furthermore, among the main components of the above-mentioned blast furnace slag, it may be desirable to contain at least 25 wt% of CaO and at least 20 wt% of SiO2 for sufficient hydration reaction, and at least 8 wt% of MgO to suppress abnormal expansion. Additionally, since the fine powder of the blast furnace slag forms hydroxides (CSH), it can contribute to forming a dense structure.

[0041] In addition, the above cement-free binder, which does not contain cement, is based on indirectly utilizing the main components of cement (CaO, SiO2, etc.) contained in fly ash and blast furnace slag. By further adding sodium carbonate and calcium hydroxide during the dry mixing process, hydration and alkali reactions can be induced through maximum dehydration polymerization under ambient temperature curing conditions after laying and compaction.

[0042] That is, the calcium silicate (CaO, SiO2) components contained in fly ash and blast furnace slag undergo a dehydration polymerization reaction when mixed with water to additionally produce calcium silicate hydrate (Calcium-Silicate-Hydroxyl) and calcium hydroxide (Ca(OH)2), and when hydration occurs, a hydrate such as calcium silicate hydrate is usually formed, followed by a positive reaction to form calcium carbonate (CaCO3), which can be utilized as a solidification base.

[0043] [Chemical Formula 1: Hydration reaction of fly ash or blast furnace slag]

[0044] 2(3CaO·SiO2)+6H2O 3CaO·2SiO2·3H2O(C3S2H3)+3Ca(OH)2

[0045] As shown in Chemical Formula 1 above, the fly ash or blast furnace slag is a latent hydraulic material in which hydroxides and calcium hydroxide are formed through a reaction with water, and subsequently, hardening is promoted through an additional reaction with carbonates, thereby exhibiting effects such as improved long-term strength and increased watertightness. In the present invention, "latent hydraulic" refers to a hydration mechanism in which, upon being stimulated by alkali (Ca(OH)2), KOH, NaOH) or sulfate (CaSO4), the thin film is destroyed and transformed into a gel, and hardening begins as ions are leached from the blast furnace slag and insoluble substances are precipitated.

[0046] Meanwhile, if the content of quicklime in the fly ash and blast furnace slag contained in the cement-free binder is below a certain range, sufficient hydrates are not formed, and thus the desired compressive strength cannot be achieved. In addition, if the content of quicklime contained in the cement-free binder exceeds a certain range, cracks may occur due to excessive premature drying shrinkage, which can significantly reduce durability.

[0047] Therefore, the above cement-free binder can be made by mixing fly ash and blast furnace slag in a weight ratio of 3:4.

[0048] The carbonated red mud is included in the soil paving material composition of the present invention. The carbonated red mud can be prepared by the following steps: a first step of preparing liquid red mud by mixing red mud sludge and water in a weight ratio of 1:20 to 1:2; a second step of preparing a mixture by mixing acid with the liquid red mud; a third step of separating the mixture into an extract and a precipitate by filtering; a fourth step of preparing a basic solution by adding NaOH to the extract; and a fifth step of preparing and recovering carbonates by injecting carbon dioxide into the basic solution.

[0049] The first step above is a step of manufacturing liquid red mud. The liquid red mud can be manufactured by mixing red mud sludge and water in a weight ratio of 1:20 to 1:2.

[0050] The above red mud sludge is a byproduct generated during the aluminum refining of bauxite ore. Furthermore, the chemical composition of the red mud sludge is SiO2, Al2O3, Fe2O3, CaO, MgO, SO3, Na2O, and K2O, and the moisture content ratio is 36%. Therefore, the red mud sludge is a strongly alkaline reddish-brown waste plastic with Fe2O3 as its main component. Table 1 shows the chemical composition of the red mud sludge.

[0051] Chemical composition (wt%) of red mud sludge SiO2 Al2O3 Fe2O3 CaO MgO SO3 Na2O K2O 38.8 16.1 22.8 3.4 0.2 0.0 10.0 0.4

[0052] Meanwhile, the aforementioned red mud sludge is difficult to recycle due to its high alkali content, and most of it is currently being disposed of through storage. If this stored red mud sludge infiltrates the ground, it can cause surface water and sewage contamination as well as soil salinization; furthermore, if exposed to the atmosphere, it can cause serious environmental damage. This highly alkaline red mud sludge can prevent global warming by increasing the solubility of carbon dioxide, a greenhouse gas, through mineral carbonation. Additionally, the carbonated minerals, which are eco-friendly and possess excellent strength and durability, can be utilized in paving materials for roads and concrete structures.

[0053] Therefore, the solid-liquid ratio of red mud sludge and water can be mixed in a weight ratio of 1:20 to 1:2. If the solid-liquid ratio is less than 1:20, the amount of ion extracted is low and may be lower than the concentration required for carbonate mineralization. In addition, if the solid-liquid ratio exceeds 1:2, the time required to separate the solid and the liquid increases, and the extraction efficiency may decrease.

[0054] The second step above is a step of preparing a mixture by mixing an acid with liquid red mud. The acid can remove impurities. The acid may be at least one selected from sulfuric acid, nitric acid, fluoride, etc. Thus, the liquid red mud, which is strongly alkaline, is neutralized with an acid and can maintain a pH of 6 to 8.

[0055] Accordingly, the sulfuric acid may be included in an amount of 6 to 8 parts by weight per 100 parts by weight of red mud sludge. As another embodiment, the present invention may mainly include 6 parts by weight of sulfuric acid per 100 parts by weight of red mud sludge. As another embodiment, the nitric acid may be included in an amount of 8.5 to 10.5 parts by weight based on 100 parts by weight of red mud sludge. If the content of sulfuric acid, nitric acid, etc. is below the range, it may be difficult to remove impurities. Furthermore, if the content of sulfuric acid, nitric acid, etc. exceeds the range, it may lead to an increase in the content of the pH adjuster below, which may cause problems with economic feasibility.

[0056] The third step above is a step of filtering the mixture prepared in the second step to separate it into an extract and a precipitate. It is a step of separating the extract and the precipitate from the mixture prepared in the second step using a centrifuge.

[0057] The fourth step above is to prepare a basic solution by adding sodium hydroxide (NaOH) to the extract. The extract exhibits a pH of 6 to 8, and a pH of 8 or higher is required to produce carbonate minerals by adding carbon dioxide. Therefore, sodium hydroxide, as a pH adjuster, can increase the carbon dioxide storage efficiency by increasing the carbonate production yield. As another example, potassium hydroxide, calcium hydroxide, magnesium hydroxide, ammonia water, etc., may be used as pH adjusters. Accordingly, the sodium hydroxide may be included in an amount of 0.3 to 0.5 wt% relative to the total weight of the extract. If the content of sodium hydroxide is less than 0.3 wt%, the carbonate yield may decrease. Furthermore, if the content of sodium hydroxide exceeds 0.5 wt%, there may be a concern regarding reduced economic feasibility.

[0058] The above fifth step is a step of producing and recovering carbonates by injecting carbon dioxide into the above basic solution. That is, the fifth step is a mineral carbonation step. Mineral carbonation refers to a method of fixing minerals by producing thermodynamically stable carbonate molecules through a carbon dioxide carbonation reaction of calcium, magnesium, sodium, etc. contained in the minerals. The carbon dioxide is injected at a rate of 0.05 to 1.0 L / min for 0.5 to 2.5 hours, and the production of carbonates can be carried out at a pressure of 2.5 to 5.0 MPa and a temperature of 0 to 10℃. The produced carbonates can be recovered by solid-liquid separation through dehydration treatment. The carbonates may be sodium bicarbonate or sodium carbonate, etc.

[0059] In addition, the fifth step may further include generating ultrasound in the base solution to promote the mineral carbonation reaction. The ultrasound not only generates a large pressure difference to vibrate water molecules violently, but also causes red mud particles to gradually scatter through high-frequency collisions, thereby forming very fine particles. When carbon dioxide is injected into the base solution, the sodium carbonate generated by the carbonation reaction occurring through rapid contact with the base solution is exfoliated by ultrasonic vibrations, allowing the carbon dioxide to penetrate into the pores of the fine particles and combine with alkali metals / earth metals (including calcium, sodium, zinc, lead, copper, nickel, etc.) to form a stable carbonate precipitate, which can greatly promote the carbonation reaction.

[0060] Accordingly, the carbonated red mud may be included in an amount of 80 to 120 parts by weight based on 100 parts by weight of cement-free binder. If the content of the carbonated red mud is less than 80 parts by weight, the solubility of carbon dioxide, the main culprit of greenhouse gases, may decrease. In addition, if the content of the carbonated red mud exceeds 100 parts by weight, it may be insignificant in terms of critical significance.

[0061] The above anti-efflorescence agent is included in the soil paving material composition of the present invention. The above anti-efflorescence agent may be a general one used in the industry, but it may be preferable to use coconut oil. The above coconut oil may contain 5 to 15 weight% palmitic acid, 1 to 10 weight% stearic acid, 30 to 70 weight% lauric acid, 10 to 30 weight% myristic acid, 5 to 15 weight% oleic acid, and 1 to 10 weight% linoleic acid.

[0062] The above stearic acid is a considerably hard fatty component among high-grade fatty acids, and while it is difficult to dissolve in water at low temperatures, it can form a strong film component and also has the function of improving the durability of the waterproof film. However, stearic acid alone is difficult to protect liquids, especially during the winter season.

[0063] The above palmitic acid is similar to stearic acid, but since its melting point is slightly lower than that of stearic acid, when dissolved, it can be smoothly combined with stearic acid to improve stability when used in winter. In addition, palmitic acid can exhibit the effect of forming a strong waterproof film, just like stearic acid.

[0064] The above lauric acid is a saturated fatty acid containing 12 carbon atoms and has the property of being rich in medium-chain fatty acids. Medium-chain fatty acids are soluble in water and have excellent foaming properties.

[0065] The above myristic acid has a strong role as an emulsifier and can serve as an auxiliary agent for liquid stabilization of hard fatty acids such as stearic acid and palmitic acid.

[0066] The above oleic acid is a major component of fatty acids contained in olive oil and is an omega-9 unsaturated fatty acid. Compared to stearic acid and palmitic acid, the above oleic acid has good liquid stability and water repellency at low temperatures. In addition, it is easily soluble in water and plays an auxiliary role in increasing liquid stability when mixed with hard components that are difficult to dissolve in water, such as stearic acid and palmitic acid.

[0067] The above linoleic acid is an unsaturated fatty acid that is insoluble in water but soluble in ether alcohol, and is a component necessary for exhibiting water-repellent function.

[0068] Accordingly, the above anti-efflorescence agent may be included in an amount of 1 to 10 parts by weight based on 100 parts by weight of cement-free binder. If the content of the above anti-efflorescence agent is less than 1 part by weight, the anti-efflorescence agent may be too diluted, making it difficult to suppress efflorescence. In addition, if the content of the above anti-efflorescence agent exceeds 10 parts by weight, the viscosity may be too high, making it difficult to spray.

[0069] The above fine aggregate is included in the soil paving material composition of the present invention. In the present invention, standard sand (KSL ISO 679) may be used as the fine aggregate. The above standard sand may be a material used in cement strength testing. The above fine aggregate refers to fine aggregate, such as sand, that passes through a standard mesh (5 mm) at a rate of 85% or more among concrete fine aggregates. Therefore, in the present invention, standard sand is mainly used as the fine aggregate. As another example, the fine aggregate may be one or more selected from coal ash, bottom ash, steel slag, copper slag, etc.

[0070] In addition, the above fine aggregate may comprise 300 to 360 parts by weight based on 100 parts by weight of cement-free binder. In the present invention, the cement-free binder and fine aggregate may be mixed mainly in a weight ratio of 1:3. Meanwhile, if the content of the above fine aggregate is less than 300 parts by weight, the strength and durability of the soil paving material composition may be weakened. In addition, if the content of the above fine aggregate exceeds 360 parts by weight, the mixing ratio of the cement-free binder is relatively reduced, resulting in weak bonding with the composition and potentially causing problems such as cracks on the surface of the soil paving material composition.

[0071] The above water is included in the soil paving material composition of the present invention. The above water may be included in an amount of 50 to 100 parts by weight based on 100 parts by weight of cement-free binder.

[0072] The soil paving material composition according to the present invention may further include a fiber reinforcement. Since the fiber reinforcement possesses both elasticity and ductility, when applied to construction such as road paving, the fiber reinforcement is densely and firmly dispersed on the matrix within the soil paving material composition, thereby significantly increasing the bonding strength between the interface of the fiber reinforcement and the matrix, which can improve compressive strength, flexural strength, impact resistance, adhesion strength, etc.

[0073] The above fiber reinforcement may be in the form of short fibers that are cut into a predetermined size after being coated with a silicone emulsion on at least one selected from polyester fibers, polyethylene terephthalate fibers, and carbon fibers made from recycled waste plastics and dried.

[0074] The above fibers are classified into warp weave and weft weave, and may consist of wefts arranged perpendicular to the warp. In the present invention, the term "warp" refers to fibers arranged in the vertical direction during weaving, and "weft" refers to fibers arranged in the horizontal direction during weaving, that is, in the width direction of the grid fibers. Furthermore, in the present invention, weft and warp refer to bundles composed of multiple individual fiber strands, and the number of fiber bundles of 2,400 to 4,800 TEX may consist of 500 to 1,000 individual strands. The above fiber reinforcement may be manufactured by the following coating-drying-cutting process.

[0075] (1) Coating

[0076] At least one of the above-mentioned polyester fibers, polyethylene terephthalate fibers, and carbon fibers may be coated by immersing them in a silicone emulsion. Known means and conditions may be used for the coating. The coated fibers can maintain a strong bonding force with the matrix in the soil paving material composition of the present invention for a longer period. As a result, the mechanical properties of the soil paving material composition of the present invention, such as compressive strength, flexural strength, impact resistance, and adhesion strength, can be significantly improved. In addition, the coated fibers can further improve the fluidity of the soil paving material composition, thereby increasing work efficiency.

[0077] (2) Drying

[0078] The above-mentioned coated fibers can be dried through heat treatment. The above-mentioned coated fibers are 50 to 100 It can be dried by heat treatment for 0.5 to 3 hours. Known drying methods may be used for the drying conditions. If the drying conditions are below the range, the bonding strength may be weakened, leading to a decrease in mechanical properties, and if the drying conditions exceed the range, it may lead to deformation of the coated fiber.

[0079] (3) Cut

[0080] The heat-treated fibers can be cut into short fibers with an average length of 5 to 10 mm. The cut fibers are used as fiber reinforcements, and the average length of the fiber reinforcement is not limited to the average length as long as it is within a range where no problems arise due to a decrease in dispersibility, fluidity, bending strength, compressive strength, etc.

[0081] Accordingly, the fiber reinforcement may be included in an amount of 1 to 5 wt% relative to the total wt% of the soil paving material composition of the present invention. If the content of the fiber reinforcement is less than 1 wt%, it may be difficult to improve compressive strength, flexural strength, impact resistance, adhesion strength, etc. In addition, if the content of the fiber reinforcement exceeds 5 wt%, it may result in a decrease in the content of other components, which may be insufficient to improve effects such as drying shrinkage.

[0082] The soil paving material composition according to the present invention may further include an expansive agent. The expansive agent may include oil refinery byproduct ash; cogeneration ash; and fly ash. Both the oil refinery byproduct ash and the cogeneration ash contain CaSO4 and CaO in significant proportions. Among these, CaSO4 reacts with C3A (3CaO·Al2O3) among cement compounds to produce needle-shaped ettringite (C3A·3CaSO4·32H2O), thereby reducing the drying shrinkage of concrete or mortar, and CaO reacts with water during the initial stage of hydration to become a hexagonal plate-shaped crystalline phase of Ca(OH)2, which expands and ultimately reduces drying shrinkage cracks. In addition, when CaO and CaSO4 coexist, CaSO4 delays the hydration of CaO and increases the amount of residual CaO that contributes to expansion in the medium and long term; therefore, oil refining byproduct ash and cogeneration ash composed of CaO and CaSO4 can be very suitable as expansion agents. Meanwhile, unlike the oil refining byproduct ash or cogeneration ash described above, fly ash does not have expansion properties, but it is composed of quartz (SiO2) and mullite (3Al2O3·2SiO2), so it is less affected by drying shrinkage and can help improve long-term strength and durability through pozzolanic reactions.

[0083] The aforementioned oil refinery byproduct ash is a byproduct in which a portion of blast furnace slag has been substituted, and refers to the byproduct generated after coke and limestone are combusted together in a fluidized bed combustion furnace, such as a fluidized bed combustion boiler. Since the oil refinery byproduct ash contains CaO, it has the effect of promoting the pozzolanic reaction of blast furnace slag. Therefore, oil refinery byproduct ash possesses excellent characteristics as a cement substitute or admixture.

[0084] Specifically, the above-mentioned oil refinery byproduct ash contains 30 to 60 wt% CaO, 10 to 40 wt% SO3, 0.1 to 10 wt% SiO2, 0.1 to 10 wt% Al2O3, 0.1 to 5 wt% MgO, 0.1 to 2 wt% NaO, etc. CaO, which constitutes the majority of the component, generates Ca(OH)2 during the hydration reaction process; acting as an expansion agent, it not only reduces drying shrinkage cracks but also enables the development of early strength. Furthermore, the Ca released from Ca(OH)2 2+ Ions react with SiO2 or Al2O3 contained in blast furnace slag fine powder to form calcium silicate hydrate (CSH) and calcium aluminate hydrate (CAH), exhibiting a hardening characteristic that demonstrates a hydration reaction mechanism similar to that of cement. Furthermore, while the aforementioned SO3 acts as a setting retarder in cement due to its high initial solubility, it acts as a reaction accelerator for blast furnace slag, which exhibits latent hydraulic properties, playing a crucial role in ensuring early workability and strength development. Additionally, the aforementioned MgO reacts with calcium hydroxide (Ca(OH)2) generated from free CaO to produce Mg(OH)2 and causes volume expansion, which has the effect of reducing cracking at long curing ages.

[0085] Therefore, due to the above components of the oil refinery byproduct ash, when the soil paving material composition according to the present invention is applied to road paving, etc., the amount of expensive activators such as sodium hydroxide (NaOH), potassium hydroxide (KOH), or sodium silicates can be reduced.

[0086] Accordingly, the above-mentioned expansive agent may be included in an amount of 3 to 8 wt% relative to the total wt% of the soil paving material composition. If the content of the above-mentioned expansive agent is less than 3 wt%, it may be difficult to prevent a decrease in shrinkage rate. In addition, if the content of the above-mentioned expansive agent exceeds 8 wt%, the shrinkage rate decreases, but it may be insignificant in terms of critical significance.

[0087] The soil paving material composition according to the present invention may further include additives. The additives may include at least one of a dispersant, an antifoaming agent, a UV stabilizer, and a thickener.

[0088] The above-mentioned dispersant can improve storage stability when the soil paving composition is used in concrete or mortar. Specifically, the dispersant adsorbs to the surface of red mud sludge particles and imparts an electric charge to the particle surface, causing mutual repulsion between the particles; this disperses aggregated particles and increases flow. Consequently, the particles are dispersed through this flow effect, thereby enhancing strength. The above-mentioned dispersant may be one or more selected from dispersants such as lignin sulfonate, polynaphthalene sulfonate, polymelamine sulfonate, or polycarboxylate-based agents.

[0089] Accordingly, the above-mentioned dispersant may be included in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of cement-free binder. Therefore, if the content of the above-mentioned dispersant is below this range, the composition may be unevenly dispersed, which may weaken the strength and durability. In addition, if the content of the above-mentioned dispersant exceeds this range, the dispersion of the composition, etc., may be insufficient and meaningless.

[0090] The above defoaming agent can improve storage stability by removing macropores within the soil paving material composition. The defoaming agent may primarily utilize oily substances with low volatility and high diffusivity, or water-soluble surfactants. Accordingly, the defoaming agent can be selected from higher alcohols, water-insoluble alcohols, silicone-based agents, phosphate ester-based agents, etc. That is, the above defoaming agent may be one or more selected from mineral oil-based defoaming agents such as kerosene and liquid paraffin, oil-based defoaming agents such as animal and vegetable oils, sesame oil and castor oil, fatty acid-based defoaming agents such as oleic acid and stearic acid, fatty acid ester-based defoaming agents such as glycerin monoricinoleate and alkenyl succinic acid liquid, oxyalkylene-based defoaming agents such as polyoxyalkylenes and acetylene ethers, alcohol-based defoaming agents such as octyl alcohol, hexadecyl alcohol and acetylene alcohol, amide-based defoaming agents such as acrylate polyamine, phosphate ester-based defoaming agents such as tributyl phosphate and sodium octyl phosphate, metal soap-based defoaming agents such as aluminum stearate and calcium oleate, and silicone-based defoaming agents such as dimethyl silicone oil, silicone paste and silicone emulsion.

[0091] Therefore, the above-mentioned defoamer may be included in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of cement-free binder. Accordingly, if the content of the defoamer is below this range, there may be issues with strength. In addition, if the content of the defoamer is below this range, it may cause problems such as cracks on the surface of concrete structures, etc., where the cement composition is used.

[0092] The above-mentioned thickener can increase the adhesive strength of the soil paving material composition. The above-mentioned thickener may use one or more selected from methylcellulose, ethylcellulose, and polysaccharide-based materials.

[0093] Accordingly, the above-mentioned thickener may be included in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the soil paving material composition. Therefore, if the content of the above-mentioned thickener is below the range, the adhesive strength may be weakened, and the strength of the red mud rapid-strengthening composition may be weakened. In addition, if the content of the above-mentioned thickener exceeds the range, workability may be reduced due to an excessive increase in adhesive strength.

[0094] The above UV stabilizer may contain hydroxybenzoate and amine light stabilizer in a weight ratio of 1:1.

[0095] Hydroxybenzoate, which is a UV absorber used as the above-mentioned UV stabilizer, can improve the light resistance effect when the cement composition is used in concrete structures, etc. That is, the above-mentioned hydroxybenzoate absorbs incoming ultraviolet (UV) rays and converts them into infrared rays, releasing heat to the outside, thereby suppressing the phenomenon of the composition decomposing due to ultraviolet rays. In addition, any substance known in the art may be used as a substitute for hydroxybenzoate as the above-mentioned UV absorber.

[0096] The amine light stabilizer used as the above-mentioned UV stabilizer can improve light resistance by inhibiting decomposition and protecting the surface when the cement composition of the present invention is used in concrete structures, etc. That is, the above-mentioned amine light stabilizer (HALS) can stop a chain photo-oxidation reaction by eliminating free radicals so that free radicals already generated in the composition due to photodecomposition by ultraviolet rays cannot cause a chain reaction. In addition, any known in the art may be used as the above-mentioned amine light stabilizer, but it is preferable that it be a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate, and it may be even more preferable that it be CIBA’s TINUVIN 292.

[0097] Accordingly, the above-mentioned UV stabilizer may be included in an amount of 0.1 to 1 part by weight based on 100 parts by weight of the soil paving material composition. If the content of the above-mentioned UV stabilizer is below this range, the ability to absorb ultraviolet rays is significantly reduced, making it difficult to protect the coating film from ultraviolet rays. In addition, if the content of the above-mentioned UV stabilizer exceeds this range, the activity of the photoinitiator is inhibited due to excessive absorption of ultraviolet rays, which may hinder the curing of the composition.

[0098] As such, the soil paving material composition containing an eco-friendly fiber reinforcement according to the embodiment of the present invention is eco-friendly as it utilizes waste plastic, reduces the amount of carbon dioxide generated, which is the main culprit of greenhouse gases, by mineral carbonating industrial by-products, and not only improves flexural strength and compressive strength by including fiber reinforcement, but also has the effect of reducing the building shrinkage rate caused by the use of expansion agents.

[0099] The following describes examples of preparation and embodiments. The following examples of preparation and embodiments are provided merely to aid in understanding the present invention.

[0101] <Preparation Example> - Carbonated red mud (Red mud mineral carbonation)

[0102] [Preparation Example 1]

[0103] Liquid red mud was prepared by mixing red mud slurry and water in a weight ratio of 1:2, and then a mixture was prepared by adding 8 parts by weight of sulfuric acid to 100 parts by weight of the liquid red mud. The mixture was separated into an extract and a precipitate using a centrifuge, and then a basic solution was prepared by mixing 5% by weight of NaOH with respect to the total weight% of the extract. Carbonate was prepared by injecting carbon dioxide into the basic solution at a rate of 0.05 L / min for 1 hour, and the prepared carbonate was recovered by dehydration treatment to separate solids and liquids, thereby mineralizing the red mud.

[0105] [Preparation Example 2]

[0106] In the above Preparation Example 1, carbonates were prepared by injecting carbon dioxide into a basic solution, except that ultrasonic vibrations were further generated to promote the mineral carbonation reaction, and the preparation was carried out in the same manner as Preparation Example 1.

[0108] <Example> - Soil paving material composition

[0109] [Example 1]

[0110] A mixture was prepared by mixing 100g of a cement-free binder with a weight ratio of fly ash to blast furnace slag of 3:4, 100g of carbonated red mud prepared according to Preparation Example 2, 5g of an anti-efflorescence agent, 300g of fine aggregate, 80g of water, and 3g of additives (1g of defoaming agent, 1g of dispersant, 1g of thickening agent). A soil paving material composition was prepared by mixing 2wt% of a fiber reinforcement and 5wt% of an expansive agent relative to the total wt% of the mixture. The soil paving material composition was poured into a mold and pressurized with a molding machine to produce a specimen measuring 10 (width) * 10 (length) * 10 (height) cm.

[0112] [Examples 2 and 3]

[0113] A soil paving material composition was prepared in the same manner as in Example 1, except that Example 2 used 80g of carbonated red mud and Example 3 used 120g of carbonated red mud.

[0115] [Examples 4 and 5]

[0116] Example 4 was prepared with a soil paving material composition identical to Example 1, except for 1 wt% fiber reinforcement and Example 5 with 5 wt% fiber reinforcement.

[0118] [Examples 6 and 7]

[0119] Example 6 and Example 7 prepared soil paving material compositions in the same manner as Example 1, except for 3 wt% of expansion agent and 8 wt% of expansion agent.

[0121] [Comparative Examples 1 to 3]

[0122] A soil paving material composition was prepared in the same manner as Example 1, except that Comparative Example 1 did not contain carbonated red mud, Comparative Example 2 contained 60g of carbonated red mud, and Comparative Example 3 contained 130g of carbonated red mud.

[0124] [Comparative Examples 4 to 6]

[0125] A soil paving material composition was prepared in the same manner as Example 1, except that Comparative Example 4 did not contain fiber reinforcement, Comparative Example 5 contained 0.5 wt% fiber reinforcement, and Comparative Example 6 contained 7 wt% fiber reinforcement.

[0127] [Comparative Examples 7 to 9]

[0128] A soil paving material composition was prepared in the same manner as Example 1, except that Comparative Example 7 did not include an expansive agent, Comparative Example 8 included 2 wt% of an expansive agent, and Comparative Example 9 included 10 wt% of an expansive agent.

[0130] [Comparative Example 10 and Comparative Example 11]

[0131] Comparative Example 10 was prepared as a soil paving material composition in the same manner as Example 1, except that it did not contain an anti-efflorescence agent and Comparative Example 11 did not contain additives.

[0133] <Test Example>

[0134] [Test Example 1] - High carbon dioxide concentration before and after red mud mineral carbonation

[0135] Red mud sludge was carbonated according to Preparation Example 1 and Preparation Example 2, and the carbon dioxide solid content before and after mineral carbonation is shown in Table 2.

[0136]

[0137] Referring to Table 2 above, it can be seen that while the carbon dioxide solubility rate of general red mud sludge is low at 0.48% due to the low content of free lime, the carbon dioxide solubility rate of Preparation Example 1, in which red mud sludge was carbonated, is 5.3%, and the solubility rate of Preparation Example 2, in which ultrasonic vibrations were generated during carbonation, is 6.5%. In other words, general red mud sludge can solubility 4.8 kg per ton, red mud sludge carbonated according to Preparation Example 1 can solubility 53 kg, and red mud sludge carbonated according to Preparation Example 2 can solubility 65 kg. Therefore, it was confirmed that Preparation Example 1 can solubility approximately 1.2 times more carbon dioxide and Preparation Example 2 can solubility approximately 1.5 times more carbon dioxide compared to general red mud sludge.

[0139] [Test Example 2] - Carbon dioxide generation and reduction rate

[0140] According to the embodiments and comparative examples of the present invention, the CO2 generation amount and reduction rate per ton of the soil paving material composition were tested. Table 3 shows the components and content of Examples 1 to 3 and Comparative Examples 1 to 3. Table 4 shows the CO2 generation amount and reduction rate according to the embodiments and comparative examples.

[0141]

[0142]

[0143] Referring to Table 4 above, it was confirmed that Examples 1 to 3, containing carbonated red mud, could reduce CO2 emissions by 15.88% to 32.94% more than Comparative Example 1, which did not contain carbonated red mud. It was confirmed that Comparative Example 2, containing 60g of carbonated red mud which is below the carbonated red mud content range of the present invention, showed an increase in CO2 emissions of more than three times compared to Example 2, which contained 80g of carbonated red mud. Furthermore, it was confirmed that Comparative Example 3, containing 130g which exceeds the carbonated red mud content range of the present invention, showed results similar to Example 3. In other words, it was found that the CO2 reduction rate increases as the carbonated red mud content increases, but becomes insignificant in critical significance when exceeding the range of the present invention. Therefore, it was confirmed that there is a significant effect within the scope of the present invention.

[0145] [Test Example 3] - Compressive strength, flexural strength, freeze-thaw

[0146] For Examples 1, 4, and 5 of the present invention and Comparative Examples 4 to 6, the compressive strength and flexural strength at 28 days of age were measured according to KS F 2405 and KS F 2408, respectively. In addition, the compressive strength after freeze-thaw was measured as the ratio of compressive strength after 100 cycles according to KS F 2456. Table 5 shows the components and content of Examples 1, 4, and 5 and Comparative Examples 4 to 6. Table 6 shows the compressive strength, flexural strength, and compressive strength after freeze-thaw according to the examples and comparative examples.

[0147]

[0149]

[0150] Referring to Table 6 above, it was confirmed that Examples 1, 4, and 5 showed significantly improved compressive strength, flexural strength, and the ratio of compressive strength after freeze-thaw compared to Comparative Example 4, which did not contain fiber reinforcement. It was found that Comparative Example 5 did not show significant improvement compared to Comparative Example 4, which did not contain fiber reinforcement. Meanwhile, as can be seen from Examples and Comparative Example 6, as the content of fiber reinforcement increases, a significant effect is exhibited on compressive strength, etc. However, if the upper limit of the fiber reinforcement content of the present invention is exceeded, it may lead to a decrease in the content of other components, such as expansion agents, thereby reducing other effects such as drying shrinkage rate.

[0152] [Test Example 4] - Drying shrinkage rate (expansion rate)

[0153] Examples 1, 6, and 7 of the present invention and Comparative Examples 7 to 9 were measured for drying shrinkage rates according to KS L 5220. Table 7 shows the components and contents of Examples 1, 6, and 7 and Comparative Examples 7 to 9. Table 8 shows the expansion rates according to the examples and comparative examples.

[0154]

[0155]

[0156] Referring to Table 8 above, it was confirmed that Examples 1, 6, and 7 all had a drying shrinkage rate of 0.05% or less on 28 days, which is superior to Comparative Example 7, which did not contain an expansion agent component, and Comparative Example 8, which contained a small amount. Meanwhile, looking at Comparative Example 9, it was confirmed that although the drying shrinkage rate improves as the expansion agent component increases, it may lead to an increase in the content of other components, such as fiber reinforcement, in the soil paving material composition of the present invention, which may lower compressive strength and hinder workability due to excessive fluidity; therefore, it was confirmed that it is desirable to include it within this range.

[0158] [Test Example 5] - Strength, etc., depending on whitening phenomenon and presence or absence of additives

[0159] Specimens prepared according to Example 1, Comparative Example 10, and Comparative Example 11 of the present invention were placed in a water bath filled with 2 cm of water and left for one week, after which they were removed, dried, and visually observed for whitening. Table 9 shows the components and content of Example 1 and Comparative Examples 10 to 11. Table 10 shows the whitening phenomenon and strength, etc., according to the presence or absence of additives in the examples and comparative examples.

[0160]

[0161]

[0162] Referring to Table 10 above, regarding the occurrence of whitening, it was confirmed that Comparative Example 10, which did not contain an anti-whitening agent, exhibited whitening on the surface of the specimen. Additionally, it was observed that there were slight differences in strength, etc., between Example 1 containing an additive and Comparative Example 11, which did not contain an additive.

Claims

Claim 1 A soil paving material composition comprising a non-cemented binder, carbonated red mud, an anti-efflorescence agent, fine aggregate, and water in a weight ratio of 1:0.8 to 1.2:0.01 to 0.1:3.0 to 3.6:0.5 to 1, and further comprising 1 to 5 wt% of a fiber reinforcement relative to the total wt%, wherein the fiber reinforcement is in the form of short fibers that are cut into a predetermined size after coating at least one selected from polyester fibers or polyethylene terephthalate fibers made from recycled waste plastic with a silicone emulsion and drying. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 The soil paving material composition containing an eco-friendly fiber reinforcement according to claim 1, wherein the carbonated red mud is prepared by: a first step of preparing liquid red mud by mixing red mud sludge and water in a weight ratio of 1:10 to 1:2; a second step of preparing a mixture by mixing acid with the liquid red mud; a third step of separating the mixture into an extract and a precipitate by filtering the mixture; a fourth step of preparing a basic solution by adding NaOH to the extract; and a fifth step of preparing and recovering carbonates by injecting carbon dioxide into the basic solution; wherein the solid content of the red mud sludge comprises 5 to 10 parts by weight per 100 parts by weight of a cement-free binder. Claim 6 A soil paving material composition containing an eco-friendly fiber reinforcement, characterized in that, in claim 5, after injecting carbon dioxide in the fifth step, it further comprises generating ultrasound to promote a mineral carbonation reaction. Claim 7 A soil paving material composition containing an eco-friendly fiber reinforcement, characterized in that, in claim 1, it further comprises 3 to 8 wt% of an expansive agent relative to the total wt%. Claim 8 A soil paving material composition containing an eco-friendly fiber reinforcement, characterized in that, in claim 1, at least one of a dispersant, an antifoaming agent, and a thickening agent is further included in an amount of 1 to 5 parts by weight based on 100 parts by weight of the cement-free binder. Claim 9 A soil paving material composition containing an eco-friendly fiber reinforcement, characterized in that, in claim 1, the carbonated red mud incorporates 65 kg or more of carbon dioxide per ton. Claim 10 A soil paving material composition containing an eco-friendly fiber reinforcement, characterized in that, in any one of claims 1 and 5 to 9, the soil paving material composition satisfies the following (a) to (c): (a) a compressive strength of 30 MPa or more and a flexural strength of 5 MPa or more after 28 days of curing; (b) a compressive strength ratio (%) after freeze-thaw of 85% or more; (c) a drying shrinkage rate of 0.05% or less.

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