Asphalt pavement filler

Abstract

The present invention relates to a filler for asphalt paving, and more specifically, to a filler for asphalt paving that can reduce carbon emissions and contribute to the stabilization of resource supply and demand by recycling inorganic industrial by-products generated in the steelmaking process and lithium sludge, which is a mineral waste generated in the lithium hydroxide production process, as well as exhibit excellent mechanical properties and peeling resistance. To this end, the filler for asphalt paving comprises steelmaking slag; and lithium sludge generated in the lithium production process.

Description

Technology Field

[0001] The present invention relates to a filler for asphalt paving, and more specifically, to a filler for asphalt paving that can reduce carbon emissions and contribute to the stabilization of resource supply and demand by recycling inorganic industrial by-products generated in the steelmaking process and lithium sludge, which is a mineral waste generated in the lithium hydroxide production process, as well as exhibit excellent mechanical properties and peel resistance. Background Technology

[0002] Generally, asphalt mixtures are referred to as asphalt or asphalt concrete, and are also called hot mix asphalt or HMA. These asphalt mixtures have been managed as group standards since January 1, 2015.

[0003] Asphalt mixtures are prepared by heating or mixing asphalt with coarse aggregates such as gravel, fine aggregates such as sand, or paving fillers such as stone powder at room temperature. They are primarily used for road paving and parking lots, and are classified into various types depending on their purpose, use, function, and construction method.

[0004] The cross-section of an asphalt pavement consists of, from top to bottom, a surface layer, an intermediate layer, a base layer, a subbase layer, a frost-prevention layer, a subgrade, and a subgrade body; among these, asphalt mixtures are used in the surface layer and the intermediate layer. In asphalt mixtures, fillers serve to reduce the gaps between aggregates. However, if too much filler is used, the asphalt mixture becomes soft, making it susceptible to plastic deformation; therefore, the usage ratio must be determined in relation to the asphalt content.

[0005] Specifically, fillers are fine particulate materials that serve to fill the voids between aggregate particles in an asphalt mixture. Generally, they are used in the form of very fine powders with a particle size of about 0.075 mm or less, mixed in an amount of about 1% to 5%, and cement, limestone powder, fly ash, etc., are used as fillers. Fillers play a role in enhancing durability by filling the space between coarse and fine aggregates in asphalt concrete. As a material that reduces spalling between asphalt and aggregates, lowers asphalt aging and plastic deformation, and increases crack resistance against microcracks, they improve durability and strength by increasing the density of the mixture and minimizing voids.

[0006] In this regard, the KS F 3501 standard for asphalt pavement fillers specifies the materials that can be used as fillers. It stipulates that the materials that can be used "must be powders of limestone, Portland cement, hydrated lime, fly ash, recovered dust, electric furnace steelmaking dust, foundry dust, various types of incineration ash, and other suitable mineral substances," and further specifies that they must not contain harmful substances such as dust, mud, organic matter, or lumpy fine particles. Additionally, the quality standards for fillers specified in KS F 3501 cover moisture content, particle size distribution, plasticity index, flow test, immersion expansion, and peeling resistance.

[0007] In other words, asphalt pavement fillers fill the gaps between aggregates within the asphalt mixture and act as a filler-binder, combining the filler with the binder, asphalt (AP).

[0008] Currently, in recycled asphalt concrete mixtures, the trend is to primarily use cement as a filler to serve the roles of binding and filling materials. However, when using Portland cement, there are disadvantages; due to its high stiffness, it fails to transfer loads from the upper layers to the lower layers, posing a risk of collapse when load-bearing capacity reaches its limit, and its functionality as a filler tends to deteriorate due to its inherent shrinkage properties.

[0009] Meanwhile, limestone powder is generally used as a filler for asphalt paving in industrial sites, and in factories manufacturing heated asphalt mixtures, recovered dust collected from the heating of aggregates is mixed with limestone powder in a certain ratio for use.

[0010] Fly ash generated from coal-fired power plants is utilized as a raw material for cement or as aggregate for roads, and is recycled at a rate of over 80%. Blast furnace slag was produced at a rate of 9,503 tons as of 2007, and most of it is used as a raw material for cement.

[0011] Slaked lime is a substance produced by undergoing additional processes following the thermal decomposition of limestone; because it is significantly more expensive than limestone powder obtained by simply crushing limestone, it is not commonly used in industrial settings.

[0012] In the case of steelmaking slag dust, it refers to the dust generated during the drying process of slag produced during the desulfurization and dephosphorization processes carried out during the steelmaking pretreatment process.

[0013] In this regard, more than 10 million tons of by-products are generated annually at the Gwangyang Steelworks, with blast furnace slag accounting for about 49%, steelmaking slag about 28%, dust and sludge about 15%, and other by-products about 8%, and the total amount generated is on the rise every year.

[0014] In the case of blast furnace slag and steelmaking slag, the entire amount generated is utilized as a raw material for cement, a substitute for natural aggregates, and a raw material for silicate fertilizers, and currently 98.4% of the generated by-products are recycled through resource recycling.

[0015] Sludge, dust, and other by-products are recycled in the steelmaking process, and by-products for which no use has been found are disposed of through methods such as incineration or landfill. Looking at the status of dust and sludge resource recovery, about 60% of the total amount generated is recycled internally, while only about 10% is recycled externally, and the proportion disposed of by landfill or incineration is about 10%.

[0016] In this regard, Korean Registered Patent 10-0243926 proposed a method for manufacturing road paving concrete using crushed waste asphalt by mixing 250 to 500 kg / m³ of Portland cement with crushed waste asphalt aggregate, and Korean Registered Patent 10-0599492 proposed a semi-rigid paving composition utilizing waste asphalt characterized by adding 1 to 40 parts by weight of cement, 5 to 15 parts by weight of a volume expansion agent including iron-based, gypsum-based, and CSA-based materials to compensate for the volume shrinkage of cement, 1 to 15 parts by weight of an indexing agent, and 0.01 to 5 parts by weight of a hardening accelerator to 100 parts by weight of waste asphalt, wherein the composition further includes 0.1 to 40 parts by weight of a filler based on 100 parts by weight of waste asphalt, and the filler comprises new aggregate, soil, weathered granite soil, waste carbon black, waste toner, About 10 substances, including anhydrous gypsum and hemihydrate gypsum, have been presented.

[0017] However, all of these technologies propose semi-rigid pavement mixtures that do not fall into the category of asphalt mixture pavements, which are characterized by flexible pavements, by using large amounts of cement and fillers. Introducing such large amounts into the mixture is not economical as it exceeds the filler content of 3 to 6% in general asphalt pavement mixtures, and because the main raw material is cement, it can be said that it retains the environmental harm of cement, which is manufactured by using coal as fuel and thermally decomposing limestone, clay, and iron ore at a high temperature of 1,450°C.

[0018] In addition, Korean registered patent 10-0788051 has disclosed a technology in which recycled asphalt aggregate is used as the main raw material, 0.01 to 0.10 parts by weight of emulsified asphalt is mixed with 1 part by weight of the recycled asphalt, and 0.02 to 0.12 parts by weight of cement is incorporated with 1 part by weight of the recycled asphalt.

[0019] As described above, conventional technologies for filling recycled asphalt mixtures consist entirely of using cement.

[0020] Meanwhile, lithium, a key material for secondary batteries, is broadly classified into lithium in the form of brine dissolved in water and lithium in the form of ore. The production process for brine-type lithium involves evaporating and concentrating lithium brine to first produce intermediates such as lithium phosphate (Li3PO4) and lithium carbonate (Li2CO3), which are then converted into lithium hydroxide.

[0021] Known methods for extracting lithium from ore include acid treatment, alkali treatment, and chlorination, and there is also a method using sulfuric acid.

[0022] The lithium production process is broadly divided into an upper process and a lower process. The upper process is a process that converts lithium ore into lithium sulfate. First, the ore is heated to a temperature of about 1,000°C to form a structure suitable for the chemical reaction that will take place later. Then, it is reacted with sulfuric acid in an environment of about 250°C to produce lithium sulfate. The lower process corresponds to a process that converts the lithium sulfate produced in the upper process into lithium hydroxide.

[0023] To produce 1 ton of such lithium hydroxide, approximately 20 tons of lithium sludge are generated, and about 800,000 tons of acidic inorganic sludge are generated annually during the beneficiation process for producing this lithium hydroxide. The generated sludge has no economic value and currently must be landfilled.

[0024] Meanwhile, the aforementioned background technology is technical information that the inventor possessed for the derivation of the present invention or acquired during the process of deriving the present invention, and it cannot necessarily be considered publicly known technology disclosed to the general public prior to the filing of the present invention. Prior art literature

[0025] Korean Registered Patent Publication No. 10-0243926 Korean Registered Patent Publication No. 10-0599492 Korean Registered Patent Publication No. 10-0788051 The problem to be solved

[0026] The present invention aims to solve the above-mentioned problems by providing an asphalt paving filler that can reduce carbon emissions and contribute to the stabilization of resource supply and demand by recycling inorganic industrial by-products generated in the steelmaking process and lithium sludge, which is a mineral waste generated in the lithium hydroxide production process.

[0027] The above and other objects and advantages of the present invention will become apparent from the following description describing preferred embodiments. means of solving the problem

[0028] The above objective can be achieved by an asphalt paving filler comprising steelmaking slag; and lithium sludge generated in the lithium production process.

[0029] Specifically, the steelmaking slag may be characterized by comprising one or more selected from the group consisting of KR slag, pulverized slag, converter slag, blast furnace slag, ladle slag, magnesium refining slag, stainless steel refining slag, electric refining slag, and combinations thereof.

[0030] Specifically, the asphalt paving filler may be characterized by including KR slag, pulverized slag, and lithium sludge.

[0031] Specifically, the above asphalt paving filler may be characterized by additionally including industrial by-products generated during the coal combustion process.

[0032] Specifically, the industrial byproduct may be characterized by comprising one or more selected from the group consisting of fly ash, bottom ash, cinder ash, and combinations thereof. Effects of the invention

[0033] According to the present invention, an asphalt paving filler exhibiting excellent mechanical properties can be manufactured by recycling inorganic industrial by-products generated in the steelmaking process and lithium sludge, which is a mineral waste generated in the lithium hydroxide production process.

[0034] According to the present invention, by utilizing continuously generated waste for manufacturing, carbon emissions can be reduced and the supply and demand of resources can be stabilized, and waste disposal costs and manufacturing costs can be effectively reduced.

[0035] In addition, the asphalt paving filler according to the present invention not only effectively prevents delamination caused by moisture by improving delamination resistance, but also exhibits superior mechanical strength compared to conventional asphalt paving fillers, which have a risk of collapse when their load-bearing capacity reaches a limit due to high rigidity and have a self-shrinking property.

[0036] However, the effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below. Brief explanation of the drawing

[0037] Figures 1 (a) to (c) are images showing the manufacturing process of an asphalt paving filler according to one embodiment of the present invention. Figures 2(a) to 2(c) are images showing the Marshall stability and flow rate test process of an asphalt paving filler according to one embodiment of the present invention. Figures 3 (a) and (b) are images showing the theoretical maximum density test process of an asphalt pavement filler according to one embodiment of the present invention. Figures 4 (a) and (b) are images related to a tensile strength ratio test of an asphalt pavement filler according to one embodiment of the present invention. Figures 5(a) and 5(b) are images showing the dynamic stability test process of an asphalt pavement filler according to one embodiment of the present invention. Specific details for implementing the invention

[0038] The present invention will be described in detail below with reference to the embodiments and drawings. These embodiments are presented merely as examples to explain the invention more specifically, and it will be obvious to those skilled in the art that the scope of the invention is not limited by these embodiments.

[0039] Furthermore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains, and in the event of a conflict, the description in this specification, including the definitions, shall prevail.

[0040] To clearly explain the proposed invention in the drawings, parts unrelated to the description have been omitted, and similar parts throughout the specification have been given similar reference numerals. Furthermore, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Additionally, the term "part" as described in the specification refers to a single unit or block that performs a specific function.

[0041] In each step, identification codes (1st, 2nd, etc.) are used for convenience of explanation and do not describe the order of the steps; the steps may be performed differently from the specified order unless a specific order is clearly indicated in the context. That is, the steps may be performed in the same order as specified, substantially simultaneously, or in the reverse order.

[0043] Hereinafter, embodiments and examples of the present invention will be described in detail with reference to the attached drawings. However, the present invention may not be limited to these embodiments, examples, and drawings.

[0045] One aspect of the present invention relates to a filler for asphalt paving comprising steelmaking slag; and lithium sludge generated in a lithium production process.

[0046] According to the present invention, an asphalt paving filler exhibiting excellent mechanical properties can be manufactured by recycling inorganic industrial by-products generated in the steelmaking process and lithium sludge, which is a mineral waste generated in the lithium hydroxide production process. In addition, by manufacturing using continuously generated waste, carbon emissions can be reduced and contribute to the stabilization of resource supply and demand, while effectively reducing waste disposal costs and manufacturing costs.

[0047] The asphalt paving filler according to the present invention not only effectively prevents delamination caused by moisture by improving delamination resistance, but also exhibits superior mechanical strength compared to conventional asphalt paving fillers that have high rigidity, pose a risk of collapse when load-bearing capacity reaches its limit, and have the property of shrinking on their own.

[0048] In one embodiment, the steelmaking slag among the components refers to an industrial byproduct and waste generated in the steelmaking process, and may include one or more selected from the group consisting of, for example, KR slag, pulverized slag, converter slag, blast furnace slag, ladle slag, magnesium refining slag, stainless steel refining slag, electro-refining slag, and combinations thereof.

[0049] Preferably, the steelmaking slag may include both KR slag and pulverized slag.

[0050] The steelmaking process proceeds in the order of: the ironmaking process, in which iron ore is put into a blast furnace and coke is burned to remove oxygen from the iron ore and melt it to produce pig iron; the molten iron pretreatment process, in which impurities in the pig iron are oxidized; the converter steelmaking process, in which molten iron is poured into a converter and high-pressure, high-purity oxygen is blown in to burn carbon and remove impurities; and the secondary refining process, which is controlled to meet the requirements for the internal quality (composition, material, etc.) of the final product. Afterward, steel products are shipped after undergoing processes such as casting and rolling.

[0051] Molten iron produced in a blast furnace has a high carbon (C) content and contains impurities such as phosphorus (P) and sulfur (S), making it brittle. To turn this molten iron into strong steel, the process of reducing the amount of carbon and removing impurities is called the molten iron pretreatment process, and a large amount of slag is generated during this process.

[0052] The molten iron pretreatment process includes the TDS (Torpedo Ladle Car desulfurization station), KR (Kanvara reactor), and HMPS (Hot Metal Pretreatment Station) methods. Among these, the KR method is a method of removing phosphorus and sulfur by immersing a stirring rod in the molten iron and rotating it, and then adding a desulfurizing agent and a dephosphorizing agent to mix and stir the molten iron.

[0053] In one embodiment, the KR slag may refer to slag generated by the KR method molten iron pretreatment process, and the pulverized slag may refer to powdered slag generated by pulverization during the refining process.

[0054] In one embodiment, the KR slag may comprise about 1 to 10 wt% MgO, about 1 to 10 wt% Al2O3, about 1 to 10 wt% SiO2, about 0.1 to 1 wt% P2O5, about 1 to 10 wt% SO3, about 50 to 70 wt% CaO, about 0.1 to 1 wt% MnO2, and about 1 to 10 wt% Fe2O3. The reason the KR slag has a high sulfur content is that it undergoes a desulfurization process as sulfuric acid is used during the process of treating spodumene, and this may occur as sulfur binds to quicklime CaO during this process.

[0055] In one embodiment, the KR slag may be included in the asphalt paving filler at about 50 to 80 weight percent. If the KR slag is included at less than about 50 weight percent or exceeds about 80 weight percent, shrinkage or delamination may occur in the asphalt paving filler produced.

[0056] In one embodiment, the pulverized slag may comprise about 5 to 10 wt% MgO, about 0.1 to 3 wt% Al2O3, about 15 to 45 wt% SiO2, about 0.01 to 0.1 wt% P2O5, about 0.1 to 1 wt% SO3, about 45 to 70 wt% CaO, about 0.1 to 0.5 wt% MnO2, and about 0.1 to 0.5 wt% Fe2O3. The pulverized slag may be attributed to the high content of SiO2 and Al2O3 in the spodumene during the process of treating the spodumene.

[0057] In one embodiment, the pulverized slag may be included in the asphalt paving filler in an amount of about 1 to 30 weight percent. If the pulverized slag is included in an amount of less than about 1 weight percent, the mechanical strength of the asphalt paving filler being manufactured may decrease, and if it exceeds about 30 weight percent, shrinkage or delamination may occur in the asphalt paving filler being manufactured.

[0058] In one embodiment, the lithium sludge among the components may refer to acidic industrial waste generated during the process of beneficiating spodumene, a lithium ore, to produce lithium hydroxide. The asphalt paving filler according to the present invention utilizes lithium sludge, which was previously discarded as industrial waste, thereby exhibiting excellent mechanical strength while being usable without peeling or shrinkage, and effectively reducing waste treatment and manufacturing costs.

[0059] In one embodiment, the pH of the lithium sludge may be in the range of about 6 to 8 up to 12 hours of measurement. Accordingly, it can be used without difficulty as a filler for asphalt paving.

[0060] In one embodiment, the lithium sludge may comprise about 1 to 2 wt% MgO, about 20 to 25 wt% Al2O3, about 45 to 50 wt% SiO2, about 0.1 to 0.5 wt% P2O5, about 15 to 20 wt% SO3, about 5 to 10 wt% CaO, about 0.1 to 0.5 wt% MnO2, and about 1 to 3 wt% Fe2O3.

[0061] In one embodiment, the lithium sludge may be included in the asphalt paving filler at about 10 to 40 weight percent. If the lithium sludge exceeds about 40 weight percent, the mechanical strength of the asphalt paving filler being manufactured may decrease.

[0062] In one embodiment, the asphalt paving filler may comprise about 50 to 80 weight% of KR slag, about 1 to 30 weight% of pulverized slag, and about 10 to 40 weight% of lithium sludge.

[0063] The weight range described above is a value calculated to ensure that the manufactured asphalt paving filler exhibits effects such as excellent mechanical strength, prevention of peeling and shrinkage, and if it falls outside this range, the described effects may not be easily achieved.

[0064] In one embodiment, the asphalt paving filler may additionally include industrial by-products generated during the coal combustion process.

[0065] In one embodiment, the industrial byproduct refers to waste generated during the coal combustion process and may include one or more selected from the group consisting of, for example, fly ash, bottom ash, cinder ash, and combinations thereof, and preferably may include fly ash.

[0066] The asphalt paving filler according to the present invention includes fly ash as an industrial byproduct, thereby enabling it to improve cohesiveness without causing chemical effects.

[0067] In one embodiment, the fly ash may be included in the asphalt paving filler in an amount of about 1 to 30 weight percent. If the fly ash is included in an amount of less than about 1 weight percent, the cohesiveness of the asphalt paving filler being manufactured may decrease, and if it exceeds about 30 weight percent, shrinkage or delamination may occur in the asphalt paving filler being manufactured.

[0068] In one embodiment, the asphalt paving filler may include KR slag, pulverized slag, lithium sludge, and fly ash.

[0069] In one embodiment, the effect described above is exerted through the organic interaction of all the components described above, and the effect may not be achieved if the active ingredient is included selectively.

[0070] In one embodiment, the asphalt paving filler may comprise about 50 to 80 weight% of KR slag, about 1 to 30 weight% of pulverized slag, about 10 to 40 weight% of lithium sludge, and about 1 to 10 weight% of fly ash.

[0071] The weight range described above is a value calculated to ensure that the manufactured asphalt paving filler exhibits effects such as excellent mechanical strength, prevention of peeling and shrinkage, and if it falls outside this range, the described effects may not be easily achieved.

[0073] Hereinafter, the structure of the present invention and the resulting effects are to be explained in more detail through specific embodiments and comparative examples. However, these embodiments are intended to explain the present invention more specifically, and the scope of the present invention is not limited to these embodiments.

[0075] [Examples 1 to 4]

[0076] Asphalt pavement filler was prepared by mixing KR slag, pulverized slag, lithium sludge, and fly ash according to the mixing ratios presented in Table 1 below (Fig. 1).

[0077] The mixing ratio of the asphalt paving filler in the example was determined by measuring the immersion expansion value of each raw material, mixing the raw materials to control the immersion expansion value, and using the amount of each raw material added and the immersion expansion value as dependent functions. As a comparative example, an asphalt paving filler currently commercially produced was used (KR slag : pulverized slag = 7 : 3).

[0078] division KR Slag volcanic slag lithium sludge Fly ash Comparative example (control group) 70 wt% 30 wt% - - Example 1 70 wt% - 30 wt% - Example 2 70 wt% 20 wt% 10 wt% - Example 3 70 wt% 10 wt% 20 wt% - Example 4 70 wt% 10 wt% 10 wt% 10 wt%

[0080] [Experimental Example 1: Particle Size Analysis (Sieve Test)]

[0081] Asphalt mixtures exhibit characteristics in that the asphalt binder coats aggregates in a thin layer and binds them together to resist traffic loads, and supports vehicle loads or other traffic loads due to the interlocking phenomenon of the aggregates. Therefore, since the particle size of the asphalt paving filler incorporated during the production of asphalt mixtures is a very important characteristic, a sieve analysis test was conducted on the asphalt paving fillers of the examples and manufacturing examples to verify whether they satisfy the particle size standards presented in the quality standards, and the results are shown in Table 2.

[0082] classification standard Comparative example Example 1 Example 2 Example 3 Example 4 Particle size analysis 0.6 ㎜ 100 100 100 100 100 100 0.3 ㎜ 95 98 95 96 96 96 0.15 ㎜ 90 95 90 91 92 92 0.075 ㎜ 70 85 72 81 84 89

[0084] As shown in Table 2 above, both the asphalt pavement fillers of the comparative example and the example met the KS standards.

[0086] [Experimental Example 2: Measurement of Plasticity Index (PI)]

[0087] The Plasticity Index (PI) is the difference between the liquid limit and the plastic limit, referring to the range of water content when the filler exists in a plastic state. According to KS standards, if the liquid limit or the plastic limit cannot be determined, it is generally designated as NP (Non-Plastic).

[0088] The plasticity index of the asphalt paving filler of the examples and manufacturing examples was measured and is shown in Table 3 below.

[0089] classification standard Comparative example Example 1 Example 2 Example 3 Example 4 Plasticity index Less than 6 NP NP NP NP NP

[0091] As shown in Table 3 above, both the asphalt pavement fillers of the comparative example and the example met the KS standards.

[0093] [Experimental Example 3: Flow Test]

[0094] Flow tests were conducted on the asphalt pavement fillers of the examples and manufacturing examples using a flow table and a flow cone as specified in KS L 5111. The procedure involved adding an appropriate amount of water to each filler, mixing them to form a filler paste, and using a flow cone to determine the water content at which the flow width reached 200 mm. The results are shown in Table 4 below.

[0095] classification standard Comparative example Example 1 Example 2 Example 3 Example 4 Flow test Less than 50% 38.2 42.5 35.5 35.4 44.2

[0097] As shown in Table 4 above, both the asphalt pavement fillers of the comparative example and the example met the KS standards.

[0099] [Experimental Example 4: Measurement of Peel Resistance (Spring Resistance)]

[0100] The asphalt mixture, prepared by mixing the asphalt paving filler of the example and manufacturing example with asphalt, was heated for 1 minute, and the degree of delamination was evaluated, and the results are shown in Table 5.

[0101] classification standard Comparative example Example 1 Example 2 Example 3 Example 4 Spring Resistance Less than 1 / 4 1 / 4 or less 1 / 4 or less 1 / 4 or less 1 / 4 or less 1 / 4 or less

[0103] As shown in Table 5, the asphalt pavement fillers of the comparative example and the example satisfied the quality standards because the peeling was less than 1 / 4 of the total.

[0105] [Experimental Example 5: Measurement of Swelling Rate]

[0106] For the asphalt paving fillers of the examples and manufacturing examples, a compaction hammer and mold specified in KS F 2337 were used, and the degree of expansion of the compacted asphalt paving fillers after absorbing water for 48 hours was measured. The results are shown in Table 6 below.

[0107] classification standard Comparative example Example 1 Example 2 Example 3 Example 4 Swelling Less than 3% 0.9 1.4 1.2 1.4 1.5

[0109] As shown in Table 6 above, both the asphalt pavement fillers of the comparative example and the example met the KS standards.

[0111] For the asphalt paving fillers of the examples and comparative examples, the test results for quality standards are comprehensively summarized in Table 7.

[0112] classification standard Comparative example Example 1 Example 2 Example 3 Example 4 Sieve test 0.6 ㎜ 100 100 100 100 100 100 0.3 ㎜ 95 98 95 96 96 96 0.15 ㎜ 90 95 90 91 92 92 0.075 ㎜ 70 85 72 81 84 89 Water Content Less than 1.0% 0.1 0.1 0.1 0.1 0.1 Plasticity index Less than 6 NP NP NP NP NP Flow test Less than 50% 38.2 42.5 35.5 35.4 44.2 Spring Resistance Less than 1 / 4 1 / 4 or less 1 / 4 or less 1 / 4 or less 1 / 4 or less 1 / 4 or less Swelling Less than 3% 0.9 1.4 1.2 1.4 1.5 Specific Gravity - 2.48 2.39 2.44 2.42 2.38

[0114] As summarized in Table 7, both the asphalt pavement fillers of the comparative example and the example satisfied the KS standards.

[0116] [Experimental Example 6: Indoor Test - Measurement of Marshall Stability and Flow Value]

[0117] The Marshall stability test is the most widely used test method for measuring the basic physical properties of asphalt mixtures. It is intended for mix design and quality control of asphalt mixtures, and measurements for each asphalt pavement filler in the examples and comparative examples were performed in accordance with the standards of KS F 2337 (Fig. 2). The results are shown in Table 8.

[0118] item Specifications Comparative example Example 1 Example 2 Example 3 Example 4 Stability 5,000 or more 13,179 13,177 13,180 13,010 13,358 Flow value 20 ~ 40 32 39 35 32 39

[0120] As shown in Table 8, when the asphalt content was fixed at 5%, the results of measurement showed that both the comparative example and the example met or exceeded the standard value, ensuring suitability for production as a product. In particular, Example 3 showed that it was almost identical to the existing product, the comparative example (control group).

[0121] The flow chart was also all included within the standard values, and like the stability results, the results of Example 3 matched the results of the comparative example (control group).

[0123] [Experimental Example 7: Indoor Test - Measurement of Theoretical Maximum Density]

[0124] The theoretical maximum density of the asphalt pavement fillers of the examples and comparative examples was measured using experimental equipment in accordance with KS F 2366 (Test method for the theoretical maximum specific gravity of asphalt mixtures). The average value of three tests is shown in Table 9, and the theoretical maximum density of the asphalt mixture can be determined through actual measurement to derive the optimal asphalt content (Fig. 3).

[0125] item Specifications Comparative example Example 1 Example 2 Example 3 Example 4 Theoretical maximum density - 2.372 2.417 2.441 2.399 2.390 Actual density - 2.286 2.288 2.285 2.285 2.278

[0127] As shown in Table 9, all of the fillers in the examples showed test values ​​that were almost similar to those of the comparative example (control group), which is a conventional product.

[0129] [Experimental Example 8: Indoor Test - Measurement of Porosity and Saturation]

[0130] The void ratio and saturation of the asphalt pavement fillers of the examples and comparative examples were measured and are shown in Table 10 below.

[0131] item Specifications Comparative example Example 1 Example 2 Example 3 Example 4 Porosity (%) 3 ~ 6 3.6 5.3 6.4 4.8 4.4 Saturation (%) 65 ~ 80 74.5 67.5 63.3 69.7 71.4

[0133] As porosity decreases, saturation increases. As shown in Table 10, compared to the existing product, the Comparative Example (control group), all Examples showed higher porosity and lower saturation. Among the Examples, Examples 3 and 4 showed the closest approximation to the test values.

[0135] [Experimental Example 9: Indoor Test - Measurement of Tensile Strength Ratio (TSR)]

[0136] The tensile strength ratio was measured for the asphalt pavement fillers of the examples and comparative examples. The tensile strength ratio test is a method for measuring the durability of an asphalt mixture against moisture, and can be obtained as the ratio of the indirect tensile strength of the asphalt mixture in a dry state to the indirect tensile strength after moisture saturation (Fig. 4). The results are shown in Table 11.

[0137] item Specifications Comparative example Example 1 Example 2 Example 3 Example 4 Tensile strength ratio 0.75 or higher 0.81 0.70 0.77 0.81 0.74

[0139] As shown in Table 11, Examples 3 and 4 passed the standard values, and among them, Example 3 was measured to be the same as the test value of the comparative example (control group), and was evaluated as having the greatest potential for future production.

[0141] [Experimental Example 10: Indoor Test - Measurement of Dynamic Stability]

[0142] The dynamic stability of the asphalt pavement fillers of the examples and comparative examples was measured and is shown in Table 12 below (Fig. 5).

[0143] item Specifications Comparative example Example 1 Example 2 Example 3 Example 4 Dynamic stability (cycles / min) 750 or more 2,545 2,322 2,652 2,852 2,284

[0145] As shown in Table 12, all examples showed test values ​​that met the specifications and showed test values ​​that were almost similar to the existing product, the comparative example (control group).

[0147] The test results described above are summarized in Table 13 below.

[0148] item Specifications Comparative example Example 1 Example 2 Example 3 Example 4 Stability 5,000 or more 13,179 13,177 13,180 13,010 13,358 Flow value 20 ~ 40 32 39 35 32 39 Porosity (%) 3 ~ 6 3.6 5.3 6.4 4.8 4.4 Saturation (%) 65 ~ 80 74.5 67.5 63.3 69.7 71.4 Aggregate void ratio 14.9 or higher 17.5 15.8 18.4 17.5 15.9 Tensile strength ratio 0.75 or higher 0.81 0.70 0.77 0.81 0.74 Dynamic stability (cycles / min) 750 or more 2,545 2,322 2,652 2,852 2,284 Theoretical maximum density - 2.372 2.417 2.441 2.399 2.390 Actual density - 2.286 2.288 2.285 2.285 2.278

[0150] As summarized in Table 13, among the examples, Example 3 showed the test analysis result closest to the existing product, the comparative example (control group).

[0152] [Experimental Example 11: Hazardous Substance Analysis - Waste Processing Test]

[0153] Lithium sludge is an industrial waste generated during the process of producing lithium hydroxide from spodumene, and it must be determined through waste process testing that there are no problems with using the waste.

[0154] Accordingly, a waste process test was conducted on the lithium sludge used in the asphalt paving filler manufactured in the example, and the results are shown in Table 14.

[0155] division Waste Management Act Standard (mg / L) Result (mg / L) lead 3 or less Non-detectable copper 3 or less Non-detectable arsenic 1.5 or less Non-detectable mercury 0.005 or less Non-detectable cyanogen 1 or less Non-detectable hexavalent chrome 1.5 or less Non-detectable cadmium 0.3 or less Non-detectable Organophosphorus 1 or less Non-detectable oil components 5 or less Non-detectable tetrachloroethylene 0.1 or less Non-detectable trichloroethylene 0.3 or less Non-detectable

[0157] As shown in Table 14, the lithium sludge used in the examples was found to be compliant with the standards of the Waste Management Act, indicating that there were no issues with the manufacture of fillers for asphalt paving.

[0159] [Experimental Example 12: Analysis of Hazardous Substances - Soil Contamination Process Test]

[0160] Lithium sludge is an industrial waste generated during the process of producing lithium hydroxide from spodumene, and it must be determined through soil contamination process tests that there is no problem with using the waste.

[0161] Accordingly, a soil contamination process test was conducted on the lithium sludge used in the asphalt paving filler manufactured in the example, and the results are shown in Table 15.

[0162] Component Waste Management Act Standards (mg / kg) Result (mg / kg) cadmium 4 0.37 copper 150 8.51 lead 200 Non-detectable zinc 300 63.6 nickel 100 23.4 hexavalent chrome 5 Non-detectable cyanogen 2 Non-detectable mercury 4 Non-detectable arsenic 25 Non-detectable Fluorine 400 297 organophosphorus compounds 10 Non-detectable Polyclonate biphenyls 1 Non-detectable phenols 4 Non-detectable benzene 1 Non-detectable toluene 20 Non-detectable Ethylbenzene 50 Non-detectable xylene 15 Non-detectable Total petroleum hydrocarbons 500 Non-detectable trichloroethylene 8 Non-detectable tetrachloroethylene Non-detectable Benzo(a)pyrene 0.7 Non-detectable 1,2-Dichloroethane 5 Non-detectable

[0164] As shown in Table 15, the lithium sludge used in the examples was found to be compliant with the standards of the Waste Management Act, indicating that there were no issues with the manufacture of fillers for asphalt paving.

[0166] As a result, all asphalt paving fillers produced in the examples obtained results satisfying all physical properties of KS F 3501. The pH of the lithium sludge was measured to be 6.25 up to 12 hours of measurement, so it was determined that there would be no problem using it as an asphalt paving filler.

[0167] In the case of the lithium sludge component, results were obtained that satisfied all the standards of the Waste Management Act in the waste process test and soil contamination process test.

[0168] In addition, the asphalt paving filler manufactured in the example and As a result of conducting indoor tests on asphalt mixtures to compare the quality of existing products (comparative examples), Example 4 satisfied the specifications 100% in Marshall stability and flow tests, void ratio, saturation, aggregate void ratio, tensile strength ratio, dynamic stability, and theoretical maximum density tests.

[0170] In this specification, only a few examples among the various embodiments performed by the inventors are described; however, the technical concept of the present invention is not limited or restricted thereto, and it is obvious that it can be modified and implemented in various ways by those skilled in the art.

Claims

Claim 1 Asphalt paving filler comprising steelmaking slag; and lithium sludge generated in the lithium production process. Claim 2 The asphalt paving filler according to claim 1, wherein the steelmaking slag comprises one or more selected from the group consisting of KR slag, pulverized slag, converter slag, blast furnace slag, ladle slag, magnesium refining slag, stainless steel refining slag, electro-refining slag, and combinations thereof. Claim 3 The asphalt paving filler according to claim 1, characterized in that the asphalt paving filler comprises KR slag, pulverized slag, and lithium sludge generated in a lithium production process. Claim 4 The asphalt paving filler according to claim 1, characterized in that the asphalt paving filler further comprises industrial by-products generated during the coal combustion process. Claim 5 In paragraph 4, the above industrial by-product comprises one or more selected from the group consisting of fly ash, bottom ash, cinder ash, and combinations thereof, for an asphalt paving filler.

Images