KR20220057697A - Epoxy TiO2-embedded high-strength-functional lightweight aggregates and preparing method the same - Google Patents

Abstract

Disclosed are: new lightweight aggregate which solves a problem of brittle fracture, which was a fundamental problem of artificial lightweight aggregate, and provides an air pollution reduction function to be structurally and functionally excellent; and a manufacturing method thereof. More specifically, provided are: high-strength lightweight aggregate which is formed by coating a hyper-crosslinked polymer, formed by a chemical reaction with a crosslinker to form a chain network, on inner pores and outer surface of the lightweight aggregate with the inner pores; and a manufacturing method thereof.

Description

Epoxy TiO2-embedded high-strength-functional lightweight aggregates and preparing method the same

The present invention relates to a lightweight aggregate that improves strength and reduces weight while acting as a reinforcement and filler for concrete when mixed with cement.

Recently, as the trend toward high-rise, large-scale, atypical and specialization of building structures is accelerated, interest in lightweight aggregates (LWA) concrete that is light and has excellent strength is increasing. When lightweight aggregate is mixed with cement, the aggregate acts as a reinforcement and filler for concrete, improving strength and reducing weight. Therefore, it is possible to greatly improve the structure's dedicated space and seismic resistance while reducing the structure's own weight and cross-section of structural members. In addition, it has the advantage of being able to manufacture lightweight aggregates with various functionalities by adding some additives when mixing lightweight aggregate raw materials.

The specific gravity, strength and durability of lightweight aggregate vary according to particle shape, surface structure, porosity distribution, raw material and its manufacturing process. In general, artificial lightweight aggregate has disadvantages in that the density and unit volume mass are low, and the water absorption rate is high and thus the strength is low (refer to Non-Patent Document 1), compared to natural aggregates. For this reason, when an artificial lightweight aggregate is applied to lightweight concrete, if penetration fracture occurs within the lightweight concrete, the resistance effect of the aggregate becomes very small and brittle fracture occurs. Accordingly, various studies are being conducted to develop artificial lightweight aggregates that can enhance the strength and durability of aggregates and exhibit various functions (see Non-Patent Documents 2 and 3), but excellent quality that can be applied to actual high-rise and large-scale structures. The development of artificial lightweight aggregates is still insufficient.

[Non-patent literature]

1. Park, C.-B., et al., Production of Ready Mixed Concrete and Evaluation of Pumpability for Practical Use of Lightweight Aggregate Concrete. Magazine of RCR, 2018. 13(4): p. 54-60.

2. Li, J.j., et al., Investigation on mechanical properties and microstructure of high performance polypropylene fiber reinforced lightweight aggregate concrete. Construction and Building Materials, 2016. 118: p. 27-35.

3. Aslam, M., et al., Manufacturing of high-strength lightweight aggregate concrete using blended coarse lightweight aggregates. Journal of Building Engineering, 2017. 13: p. 53-62.

4. Hou, S., S. Razzaque, and B. Tan, Effects of synthesis methodology on microporous organic hyper-cross-linked polymers with respect to structural porosity, gas uptake performance and fluorescence properties. Polymer Chemistry, 2019. 10(11): p. 1299-1311.

5. Huang, J. and S.R. Turner, Hypercrosslinked Polymers: A Review. Polymer Reviews, 2018. 58(1): p. 1-41.

6. Gatti, G., et al., On the Gas Storage Properties of 3D Porous Carbons Derived from Hyper-Crosslinked Polymers. Polymers, 2019. 11(4): p. 588.

7. Chen, Y., et al., Cobalt-Doped Porous Carbon Nanosheets Derived from 2D Hypercrosslinked Polymer with CoN4 for High Performance Electrochemical Capacitors. Polymers, 2018. 10(12): p. 1339.

8. Castaldo, R., et al., Microporous Hyper-Crosslinked Polystyrenes and Nanocomposites with High Adsorption Properties: A Review. Polymers, 2017. 9(12): p. 651.

9. Liu, Y., et al., Hydroxyl-Based Hyper-Cross-Linked Microporous Polymers and Their Excellent Performance for CO2 Capture. Industrial & Engineering Chemistry Research, 2018. 57(50): p. 17259-17265.

10. Li, B., et al., Hypercrosslinked microporous polymer networks for effective removal of toxic metal ions from water. Microporous and Mesoporous Materials, 2011. 138(1): p. 207-214.

11. Tan, L. and B. Tan, Hypercrosslinked porous polymer materials: design, synthesis, and applications. Chemical Society Reviews, 2017. 46(11): p. 3322-3356.

12. Wu, Z., et al., Liquid oxygen compatible epoxy resin: modification and characterization. RSC Advances, 2015. 5(15): p. 11325-11333.

13. Tercjak, A., Chapter 5 - Phase separation and morphology development in thermoplastic-modified thermosets, in Thermosets (Second Edition), Q. Guo, Editor. 2018, Elsevier. p. 147-171.

14. Lasek, J., Y.-H. Yu, and JCS Wu, Removal of NO _x by photocatalytic processes. Journal of Photochemistry and Photobiology C: Photochemistry Reviews, 2013. 14: p. 29-52.

15. Dalton, JS, et al., Photocatalytic oxidation of NO _x gases using TiO2: a surface spectroscopic approach. Environmental Pollution, 2002. 120(2): p. 415-422.

16. Fernandes, C.N., et al., Using TiO2 nanoparticles as a SO2 catalyst in cement mortars. Construction and Building Materials, 2020. 257: p. 119542.

The present invention is to solve the problem of brittle fracture, which was a fundamental problem of artificial lightweight aggregate, and at the same time provide an additional air pollution reduction function to provide a new method of structurally and functionally excellent lightweight aggregate and a method for manufacturing the same.

In order to solve the above problems, the present invention provides a hyper-crosslinked polymer in which a chain network is formed by chemical reaction with a crosslinker in a lightweight aggregate having internal pores formed within the internal pores of the lightweight aggregate. And it provides a high-strength lightweight aggregate coated on the outer surface.

In addition, the cross-linking polymer provides a high-strength lightweight aggregate, characterized in that it increases the mechanical strength and gas permeability in the pores of the lightweight aggregate.

In addition, the polymer is an epoxy resin, and the crosslinking agent provides a high-strength lightweight aggregate, characterized in that the triethylenetetramine (triethyeletetramine; TETA).

In addition, it provides a high-strength lightweight aggregate characterized in that the photocatalytic inorganic particles are coated together.

In addition, the inorganic particles provide a high-strength lightweight aggregate, characterized in that TiO ₂ nanoparticles.

In order to solve the another problem, the present invention provides a crosslinker and a monomer or oligomer that reacts with the crosslinker to form a hyper-crosslinked polymer of a chain network ) embedding the mixed solution containing the internal pore formed in the lightweight aggregate; provides a method for manufacturing high-strength lightweight aggregate comprising.

In addition, the embedding provides a method for manufacturing high-strength lightweight aggregate, characterized in that performed under negative pressure conditions.

In addition, the crosslinking agent provides a method for producing high-strength lightweight aggregate, characterized in that used in an amount of 10 to 40 parts by weight based on 100 parts by weight of the monomer or oligomer.

In addition, the mixed solution includes water or alcohol, and the concentration of the monomer or oligomer is 6 to 12% by weight.

In addition, the mixed solution provides a high-strength lightweight aggregate manufacturing method, characterized in that it further comprises photocatalytic inorganic particles.

The present invention combines a hyper-crosslinked polymer (HCP) with the internal pores of a lightweight aggregate to improve the strength of the pores by additional physical/chemical bonding between the HCP and the pore surface while maintaining the lightweight of the lightweight aggregate wanted to do To this end, a solution containing HCP epoxy (epoxy) was penetrated into the internal pores of the lightweight aggregate under a negative pressure condition, and a coating method of crosslinking and polymer polymerization as a post-treatment was applied to the lightweight aggregate. In addition, TiO ₂ nanoparticles (titanium oxide nanoparticles (NPs)) with photocatalytic properties were added together with epoxy to give functionality to reduce NO _x and SO _x . Through this, it was confirmed that the strength, hydrophobicity, and NO _x /SO _x reduction characteristics of the aggregate were maintained because the epoxy-TiO ₂ coated on the internal pores and external surface of the lightweight aggregate was not separated from the lightweight aggregate even in an external environment such as rain.

1 is a view for explaining the manufacturing process of an epoxy-TiO ₂ embedded lightweight aggregate according to an embodiment of the present invention. Chemical structures of the epoxy resin and cross-linking agent filled in (c) and (c) chemical structures of the epoxy polymer after cross-linking are shown.
2 is a view showing the results of comparing the properties of lightweight aggregates according to the coating conditions in the experimental examples of the present invention, general lightweight aggregates, lightweight aggregates coated with epoxy-TiO ₂ under atmospheric pressure, and lightweight aggregates coated with epoxy-TiO ₂ under negative pressure. (a) surface and cross-sectional images, (b) fracture rate, and (c) ATR-FTIR spectra of a cross section of a lightweight aggregate are shown.
Figure 3 is a view showing the results of optimization of the properties of the lightweight aggregate according to the concentration of the epoxy-TiO ₂ composite solution in the experimental example of the present invention, (a) six types of epoxy concentration conditions (0, 3, 6, 9 , 12 and 15 wt%) images of epoxy-TiO ₂ -embedded high strength functional LWA, (b) SEM images of epoxy-TiO ₂ -embedded high strength functional LWA at 9 wt% concentration, EDS elemental analysis images of C and Ti and (c) fracture rate and (d) weight change of epoxy-TiO ₂ -embedded high-strength functional LWA according to changes in epoxy coating concentration conditions.
4 is a view showing the NOx / SOx adsorption capacity measurement result of the epoxy-TiO2-embedded high strength functional LWA in the experimental example of the present invention, (a) the exterior and internal reaction chamber image of the NO _x /SO _x gas analysis system, and the epoxy -(b) NO _x and (c) SO _x reduction measurement result of TiO2-embedded high-strength functional LWA, (e) NO _x gas reduction measurement result after repeated washing with water 5 times, and (f) by the number of times of water washing The change trend of NO _x gas reduction rate is shown.

Hereinafter, the present invention will be described in detail through preferred embodiments. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention. Accordingly, since the configuration of the embodiments described in the present specification is only the most preferred embodiment of the present invention and does not represent all the technical spirit of the present invention, various equivalents and modifications that can be substituted for them at the time of the present application It should be understood that there may be

In the present invention, a hyper-crosslinked polymer in which a chain network is formed by chemical reaction with a crosslinker in a lightweight aggregate having internal pores is coated on the internal pores and external surfaces of the lightweight aggregate. Disclosed is a lightweight aggregate.

In the present invention, the polymer can be applied as long as it can be coated on the internal pores and external surfaces of the lightweight aggregate to improve the strength of the lightweight aggregate, but preferably an epoxy resin can be applied, and in this case, the crosslinking agent is triethylenetetramine ( triethyeletetramine (TETA) is preferred.

In the present invention, inorganic particles having photocatalytic properties may be coated together with the epoxy, and preferably, TiO ₂ nanoparticles may be coated together to provide functionality for reducing NO _x and SO _x .

The high-strength lightweight aggregate according to the present invention comprises a crosslinker and a monomer or oligomer that reacts with the crosslinker to form a hyper-crosslinked polymer of a chain network It is manufactured including; embedding the mixed solution into the lightweight aggregate having internal pores. In one embodiment of the present invention, the monomer or oligomer may be a monomer or oligomer of epoxy.

In the present invention, in the case of a polymer in which long polymer chains are entangled with each other and occupy a large volume compared to the molecular weight, it is difficult to penetrate into small pores. Allow the crosslinking and polymer polymerization reaction to proceed.

In addition, in the present invention, a means is considered in which the epoxy resin effectively penetrates into the interior of the lightweight aggregate to improve strength by firmly bonding to the pore surface, and for this purpose, the embedding may be performed under negative pressure conditions.

The amount of the crosslinking agent used may be 10 to 40 parts by weight based on 100 parts by weight of the monomer or oligomer in consideration of the balance of strength improvement and lightness maintenance through an appropriate crosslinking reaction and polymerization induction after penetration of the pores of the epoxy. and preferably 20 to 30 parts by weight.

Meanwhile, in the present invention, when preparing the mixed solution, photocatalytic inorganic particles such as TiO ₂ nanoparticles are further added to provide functionality to reduce NO _x and SO _x .

On the other hand, in the present invention, in order to slow the reaction rate with the crosslinking agent during the preparation of the epoxy-TiO2 composite solution, water or alcohol such as ethanol, methanol, or isopropyl alcohol is added to the high viscosity epoxy to lower the viscosity so that the epoxy is a monomer Alternatively, crosslinking and polymer polymerization may proceed after smoothly penetrating the pores in an oligomeric state. In this case, it is preferable that the concentration of the monomer or oligomer in the mixed solution is 6 to 12% by weight.

Hereinafter, the present invention will be described in detail with reference to an experimental example.

Experimental method

(1) Epoxy-TiO ₂ Embedded high-strength lightweight aggregate

High-strength functional lightweight aggregate is embedded with a mixture of epoxy resin and crosslinker; CM-ER-Thin, R&B Co. Ltd. At the same time, it was manufactured in a way that it was coated on the external surface. First, to reduce contaminants including dust on the surface of the artificial lightweight aggregate, the general lightweight aggregate was washed in running water and then dried in the air for 15 hours. An epoxy solution was prepared by mixing isopropyl alcohol (IPA, DAEJUNG) with epoxy in 6 ratios of 0, 3, 6, 9, 12 and 15 wt%. At this time, the crosslinker was fixed at 25 wt% of the epoxy. After that, the epoxy solution and TiO ₂ (titanium(IV) oxide, ReagentPlus®, Sigma _- Aldrich) NPs are mixed at a mass ratio of 10:1, and then ultrasonicated to prepare an epoxy-TiO2 composite solution. did The prepared epoxy-TiO ₂ mixed solution was embedded in the lightweight aggregate under normal or negative pressure coating conditions. In the case of normal pressure coating, after dipping the lightweight aggregate in the epoxy-TiO ₂ mixed solution for 60 minutes at room temperature and normal pressure (20℃, 1 atm), the lightweight aggregate is removed from the solution and in the air for 8 hours. dried. In the case of negative pressure coating, the epoxy-TiO ₂ mixed solution containing the lightweight aggregate is placed in a vacuum oven (SH-VDO-08NG, SH SCIENTIFIC) and maintained at a negative pressure of 600 Torr for 30 minutes. It was taken out from and dried at room temperature and normal pressure (20°C, 1 atm) for 8 hours.

(2) material properties of aggregate

In order to confirm the amount of epoxy-TiO ₂ coated on the general lightweight aggregate, the weight of the lightweight aggregate before and after the epoxy-TiO ₂ coating was measured. Epoxy-TiO ₂ The crushing rate of lightweight aggregate before and after coating was measured with an aggregate impact testing machine (HJ-2230, HEUNG JIN TESTING MACHINE CO. LTD.). According to the BS 812-112 standard (method for determination of aggregate impact value (AIV)), the crushing rate is to crush the aggregate by vertically dropping a weight of 14 kg from 381 mm above the surface of the aggregate 15 times. After filtering through a sieve with an aperture of 2.36 mm, the difference in weight before/after crushing is converted into a percentage. Whether the epoxy was evenly inserted into the pores of the lightweight aggregate was analyzed by ATR-FTIR (Attenuated total reflection Fourier-transform infrared) spectroscopy (Nicolet iS50, Thermo-Fisher Scientific). Through FE-SEM (Field emission scanning electron microscopy, JSM-7610F PLUS, JEOL) and EDS (energy dispersive X _- ray spectrometer, Inca x-sight model 7557, Oxford Instruments), existence was confirmed.

(3) SO _x and NO _x adsorption properties of aggregates

The NO _x and SO _x gas reduction effect of the epoxy-TiO ₂ embedded lightweight aggregate was confirmed using the NO _x /SO _x gas analysis system (Invisible Co.). 500 g of epoxy-TiO ₂ embedded lightweight aggregate was placed in an open box of 705mm (width, W) Х 210mm (length, L) Х 105mm (height, H) in an open box with the size of NO _x /SO _x gas analysis system. placed in the main chamber. After that, ultraviolet light (UV light, UV intensity ~1.2 mW/cm2) was irradiated at a position where the distance from the lightweight aggregate was 220 mm. The amount of NO and SO ₂ gas injected into the chamber was controlled by a mass flow controller (3660, KOFLOC) and a reader (readout, MR-300, MJ technics). When measuring NO _x reduction, 303.0 μmol/mol of NO gas and N ₂ gas were supplied into the chamber at a rate of 3.8 sccm and 3 slm, respectively. When measuring SO _x reduction, 300.0 μmol/mol of SO ₂ gas and N ₂ gas were supplied into the chamber at a rate of 19.5 sccm and 0.5 slm, respectively. After injecting for about 2 hours so that the concentration of NO or SO ₂ in the chamber became 1 ppm, the concentration of 1 ppm was maintained for 3 hours. After irradiating ultraviolet rays, the NO _x or SO _x concentration inside the chamber was measured. A NO _x analyzer (MEZUS-210, Kemik Corporation) and an SO _x analyzer (MEZUS-110, Kemik Corporation) were used to measure the concentration.

(4) Change in NO _x reduction efficiency of epoxy-TiO ₂ embedded lightweight aggregate according to water washing

After washing the epoxy-TiO ₂ embedded lightweight aggregate, the following process was performed to confirm the change in the NO _x reduction efficiency. First, 500 g of the epoxy-TiO ₂ coated lightweight aggregate subjected to the NO _x reduction experiment was transferred to a sieve (diameter ~175 mm) having an aperture of 2 mm. After placing a spray gun (AS ONE) at a height of 300 mm above the epoxy-TiO ₂ embedded lightweight aggregate, water was sprayed on the entire surface of the epoxy-TiO ₂ embedded lightweight aggregate at a rate of 1,250 ml/min for 10 minutes. The wet epoxy-TiO ₂ embedded lightweight aggregate was naturally dried at room temperature for 12 hours to dry completely. Thereafter, the NO _x reduction effect of the dried epoxy-TiO ₂ coated lightweight aggregate was measured.

Experiment result

A hyper-crosslinked polymer (HCP), a permanent microporous polymer material, is a material capable of forming a polymer-chain network by chemical reaction of a monomer/oligomer and a cross-linking agent. Because of its many advantages such as various synthesis methods, easy functionalization, high surface area, and mild reaction conditions, HCP is very suitable for energy and environmental fields such as gas storage, carbon capture/removal, pollutant separation/removal, and catalyst. The utility is high (refer to Non-Patent Documents 4 to 7). When this HCP is bonded to the internal pores of the lightweight aggregate, the strength of the lightweight aggregate can be improved by physical/chemical bonding between the HCP and the pore surface while maintaining the lightness of the lightweight aggregate. At this time, in the present invention, a method for functionalizing lightweight aggregates by uniformly compositing with HCP TiO ₂ NPs capable of adsorbing and decomposing HCP as well as air pollutants SO _x and NO _x was proposed.

1(a) shows a method of infiltrating a monomer and a crosslinking agent capable of forming a micropore network into the internal pores of a lightweight aggregate under negative pressure conditions, and embedding HCP into the lightweight aggregate through post-treatment crosslinking and polymer polymerization. is indicating Long polymer chains are entangled with each other and, in the case of a polymer occupying a large volume relative to the molecular weight, it is difficult to penetrate into small pores. Therefore, it is necessary to control material mixing and reaction time so that crosslinking and polymer polymerization reactions can proceed after penetrating into the pores in the form of a monomer or oligomer having a small volume and penetrating into the pores. In the present invention, a typical epoxy resin among HCPs is used to facilitate crosslinking and polymerization under mild reaction conditions. Here, a high-viscosity material that can be converted into a polymer through cross-linking or polymerization was mixed with a cross-linking agent (crosslinker or hardener), and then cured. When epoxide groups are chemically bonded to the inner pore surface of the lightweight aggregate during the crosslinking reaction and polymerization, additional physical/chemical bonding between the epoxy and the pore surface while maintaining the light weight of the lightweight aggregate It is possible to improve the strength of lightweight aggregates. In addition, TiO ₂ NPs, which are photocatalysts, were mixed with the epoxy solution to reduce NO _x and SO _x , which are typical air pollutants. Epoxy-TiO ₂ Composite solution is prepared by adding IPA to a high-viscosity epoxy resin to slow the reaction rate with a crosslinking agent to lower the viscosity, mixing TiO ₂ NPs, and then uniformly dispersing through ultrasonic waves made it When the prepared epoxy-TiO ₂ mixed solution is embedded in a lightweight aggregate, the mixed solution cannot penetrate into the pores due to the air present in the pores of the lightweight aggregate and only the outer surface of the aggregate is coated. In order to solve this problem, by maintaining a vacuum state (600 Torr) when immersing the lightweight aggregate in the mixed solution, the internal air of the lightweight aggregate escapes by vacuum and then the mixed solution flows into the pores of the lightweight aggregate due to capillary action. to be easily penetrated.

1(b) shows a bisphenol-A-based epoxy resin having an epoxide functional group at the end of one of the HCPs and four amine functional groups as one of the crosslinking agents. shows the chemical structure of TETA (triethylenetetramine) with groups. Epoxy resin is a small molecule or oligomer, and has a smaller molecular weight and volume compared to a crosslinked polymer, so it can easily penetrate into the pores of a lightweight aggregate. Epoxy resin and crosslinking agent are penetrated into the pores of the lightweight aggregate, and after a certain period of time, polymerization occurs by the crosslinking reaction, and the network of polymer chains with micropores becomes the lightweight aggregate. formed inside the void. At the same time, ceramic components (ceramic components, SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , CaO, MaO, Na ₂ O, etc.) Because it can react with excessive chemical reaction, the strength of lightweight aggregate can be improved by bonding with the pore surface of the aggregate. In addition, even if TiO ₂ NPs with photocatalytic properties are inserted into the epoxy, due to the microporous network structure, which is a unique property of HCP, there is no effect on the inflow of SO _x and NO _x gases, SOx and NOx gas decomposition function can be provided ₍ refer _nonpatent literature 8-11).

2 shows the results of confirming the strength difference and the degree of internal penetration of the lightweight aggregate according to the method of coating the epoxy-TiO ₂ solution on the aggregate when manufacturing high-strength lightweight aggregate for adsorption of air pollutants. For the strength of lightweight aggregates, an aggregate impact testing machine, a device that can relatively compare the difference between impact resistance and resistance to static compressive load, was used. It is possible to determine the hardness of lightweight aggregates by measuring the impact resistance and crushing amount of the lightweight aggregates. In addition, the degree of penetration of epoxy-TiO ₂ into the lightweight aggregate was confirmed through ATR-FTIR spectroscopy analysis of the central part of the lightweight aggregate by crushing the coated lightweight aggregate.

Figure 2 (a) shows raw (pristine) LWA, a lightweight aggregate coated with epoxy-TiO ₂ under normal pressure, and a lightweight aggregate coated with epoxy-TiO ₂ under a negative pressure (600 Torr). Due to the air present in the pores of the lightweight aggregate, it is difficult for the epoxy-TiO ₂ mixed solution to penetrate into the pores at normal pressure. Therefore, when coating the lightweight aggregate with epoxy-TiO ₂ , by proceeding under a negative pressure condition of 600 Torr, the air present in the pores of the lightweight aggregate was removed, and the epoxy-TiO ₂ mixed solution was all absorbed into the pores of the lightweight aggregate. . As the brown unprocessed LWA was coated with epoxy-TiO ₂ , white TiO ₂ NPs were distributed on a gray background as a whole. As a result of confirming the change in strength according to the coating conditions of the lightweight aggregate, the raw LWA, which showed a fracture rate of 38.7 ± 1.5%, was reduced to 31.6 ± 1.3% (normal pressure coating) and 21.1 ± 0.7% (negative pressure coating) depending on the epoxy-TiO ₂ coating. The fracture rate value decreased (see Fig. 2(b)). It was confirmed that the epoxy-TiO ₂ coating increased the strength of the aggregate, and in particular, the crushing rate could be reduced by 45% compared to general lightweight aggregates through negative pressure coating. This is because the epoxy coated by crosslinking and polymerization on the surface of the pores of the lightweight aggregate containing a large number of pores acts as a binder. After the coated epoxy was filled between the pores of the lightweight aggregate, it was firmly bonded to absorb the shock acting on the aggregate, thereby increasing the strength of the aggregate.

Figure 2(c) shows the results of ATR-FTIR spectra measured for the central portion of the lightweight aggregate for each coating condition. In raw LWA and epoxy-TiO ₂ atmospheric pressure coated lightweight aggregate, no peak related to epoxy was observed. On the other hand, in the lightweight aggregate coated with epoxy-TiO ₂ under negative pressure, a peak due to stretching of OH of 3355.75 cm ^-1 to epoxy and a CH stretching vibration peak of a CH ₃ group of 2970.34 cm ^-1 were observed. Including, aromatic peaks of 1607.40 and 1508.08 cm ^-1 and COC stretching peaks of 1227.00 cm ^-1 were confirmed (see Non-Patent Document 12). These results prove that, in the case of atmospheric pressure coating, only the surface of the lightweight aggregate is coated with epoxy, and in the case of negative pressure coating, the epoxy effectively penetrates into the interior of the lightweight aggregate and firmly bonds to the pore surface, thereby increasing the strength.

Epoxy-TiO ₂ -embedded high-strength-functional LWA (epoxy-TiO2 _- embedded high-strength-functional LWA (epoxy-TiO2-embedded high-strength-functional) LWA) strength difference occurred. 3 shows the characteristics of the functional lightweight aggregate according to the concentration of epoxy in the epoxy-TiO ₂ mixed solution coated on the lightweight aggregate. The mixing amount of TiO ₂ was mixed with the epoxy solution in which IPA and epoxy were mixed at a mass ratio of 10:1, thereby maintaining a constant TiO ₂ ratio in the total epoxy-TiO ₂ mixed solution. Figure 3(a) is an epoxy-TiO ₂ -embedded high-strength functional LWA coated with a solution prepared at 0, 3, 6, 9, 12 and 15 wt% of the total epoxy-TiO ₂ mixed solution. represents an image. As the general lightweight aggregate is coated with epoxy-TiO ₂ , white TiO ₂ NPs are evenly distributed inside and on the surface of the aggregate. At this time, the epoxy not only serves as a binder on the surface of the internal pores of the aggregate, but also serves to hold the TiO ₂ so that it can be stably positioned inside and on the surface of the aggregate in an embedded form. On the other hand, when the concentration of epoxy in the epoxy-TiO ₂ mixed solution exceeds 12 wt%, not only the viscosity increases as the amount of the epoxy resin increases, but also the reaction of the crosslinking reaction is accelerated due to the increase in the concentration, resulting in a rapid decrease in the molecular weight of the crosslinked epoxy polymer. increased significantly. In this case, the volume of the epoxy polymer increased and it was difficult to penetrate into the pores of the lightweight aggregate, and as the solubility of the epoxy polymer decreased, phase separation occurred and the layers were separated (see Non-Patent Document 13). . In addition, as the dispersion degree of epoxy and TiO ₂ in the epoxy-TiO ₂ mixed solution decreased, the epoxy-TiO ₂ was not uniformly coated on the inside and surface of the lightweight aggregate, but agglomerated.

In order to check whether the epoxy-TiO ₂ is evenly distributed inside the lightweight aggregate, EDS measurement was performed. Figure 3(b) shows the results of SEM and EDS measurements for the inside after crushing the negative pressure-coated lightweight aggregate with an epoxy-TiO ₂ mixed solution containing 9 wt% of epoxy. The SEM image shows that the epoxy-TiO ₂ penetrates into the pores while maintaining the pores inside the lightweight aggregate, and the C and Ti elements measured in EDS mapping are inside the silver lightweight aggregate. It shows that the epoxy-TiO ₂ is evenly distributed.

3(c) and 3(d) show the fracture rate (AIV) and weight change tendency of the epoxy-TiO ₂ -embedded high strength functional LWA according to the epoxy concentration. As the epoxy concentration increased, the fracture rate (AIV) of the epoxy-TiO ₂ -embedded high strength functional LWA was 35.8 ± 0.7, 27.2 ± 1.8, 24.7 ± 1.7, 21.1 ± 0.7, 21.8 ± 0.7 and 18.4 ± 1.3% (0, 3 , 6, 9, 12 and 15 wt%) were gradually decreased (see Fig. 3(c)). As the epoxy concentration increased, the amount of epoxy-TiO ₂ penetrated into the lightweight aggregate increased, and the strength of the aggregate increased due to the role of the epoxy as a binder and shock absorbing properties. In addition, referring to the results of FIG. 3(d), as the epoxy concentration increases, the weight of the epoxy-TiO ₂ -embedded high-strength functional LWA increases as the amount of epoxy-TiO ₂ increases, 0.6 ± 0.1, 9.9 ± 1.3, 12.1 ± 3.3, 17.3 ± 2.0, 18.2 ± 1.0, and 19.3 ± 2.6% (0, 3, 6, 9, 12 and 15 wt%) were gradually increased. Based on the epoxy concentration of 9 wt%, which is the optimal coating condition in which the aggregation of epoxy-TiO ₂ does not occur, the crushing rate was reduced by half, while the weight increase only increased by 0.2 times.

TiO ₂ NPs contained in epoxy-TiO ₂ -embedded high-strength functional LWA is a typical photocatalytic material, and has the characteristic of decomposing and reducing NO _x and SO _x gases, which are typical air pollutants when irradiated with ultraviolet rays. TiO ₂ has a band gap of 3.2 eV, absorbs ultraviolet rays with a wavelength of 386 nm or less, and excites electrons in the valence band (VB) to the conduction band (CB). Through this, a hole(h ⁺ ) is formed in VB and an electron(e ^- ) is formed in CB. The hole in VB reacts with water molecules adsorbed on the aggregate to cause an oxidation reaction to generate hydroxyl radicals (OH*?*). On the other hand, electrons in CB reduce oxygen in the atmosphere to generate superoxide species (O2 ^- *?*). The hydroxyl radical and superoxide species change NO _x gas into nitrates and SO _x gas into sulfites and sulfates through a reaction (see Non-Patent Documents 14 to 16).

Fig. 4(a) shows a NO _x /SO _x gas analysis system. The epoxy-TiO ₂ -embedded high-strength functional LWA was placed in the main chamber, and the NO _x or SO _x gas reduction efficiency was measured at a UV intensity condition of 1.2 mW/cm 2 . Epoxy-TiO ₂ -embedded high-strength functional LWA was produced with an epoxy concentration of 9 wt%, which showed excellent strength characteristics without the occurrence of agglomeration of epoxy-TiO ₂ . 4(b) and 4(c) show the NO _x and SO _x reduction performance characteristics of the epoxy-TiO ₂ -embedded high-strength functional LWA. During the measurement, after waiting for 5 hours until the concentration in the chamber was maintained constant while injecting NO _x or SO _x gas into the NO _x /SO _x gas analysis system, ultraviolet rays were irradiated. Simultaneously with UV irradiation, the NO _x or SO _x gas concentration in the chamber immediately started to decrease, and the maximum reduction rates were 90.3% (NO _x ) and 92.8% (SO _x ). In the case of NO _x gas reduction characteristics, the concentration of NO _x gas in the chamber decreased rapidly until about 100 minutes after UV was turned on, and then the concentration of about 0.1 ppm was maintained until 12 hours. In the case of SO _x gas reduction characteristics, the concentration of SO _x gas in the chamber continued to decrease until about 6 hours after UV was turned on, and then the concentration of about 0.1 ppm was maintained until 12 hours.

As lightweight aggregates are applied to buildings exposed to external environments, they are continuously exposed to washing environments such as rain. In the case of the fabricated epoxy-TiO ₂ -embedded high-strength functional LWA, TiO ₂ NPs are composited with the epoxy, so that it can withstand the washing environment stably. 4(e) and 4(f) show the results of continuous reduction in efficiency according to repeated water washing. After washing with water the epoxy-TiO ₂ -embedded high-strength functional LWA for which the NO _x gas reduction measurement was performed once, the NO _x gas reduction was re-measured, and the washing and the NO _x gas reduction measurement were repeated a total of 5 times. Even after repeated washing 5 times, the NO _x gas reduction rates were 87.7, 86.5, 85.7, 84.0 and 86.1%, showing stable reduction characteristics.

In the present invention, in order to compensate for the weak strength of lightweight aggregates, one of HCPs, epoxy, was used as a reactive binder for surface bonding of lightweight aggregates and as an external shock absorber. In addition, by adding TiO ₂ NPs together with epoxy, the functionality of reducing NO _x and SO _x which are air pollutants was also imparted. At this time, even if the epoxy is coated on the TiO ₂ NPs surface, the NO _x /SO _x gas and the gases decomposed by the TiO ₂ NPs can easily permeate due to the properties of HCP that forms micropores during polymer polymerization and crosslinking. did Epoxy-TiO ₂ completely penetrated into the pores of the lightweight aggregate through the negative pressure coating method, and by controlling the epoxy concentration from 0 wt% to 15 wt%, a special section where the strength can be improved without significantly increasing the weight of the lightweight aggregate explored. The fracture rate of the epoxy-TiO ₂ -embedded high-strength functional LWA coated with 9 wt%, which is an ideal condition in which the aggregation of epoxy does not occur, was 21.1%, which was reduced by half compared to the 38.7% of general lightweight aggregate. In addition, it was confirmed that, due to TiO ₂ NPs having photocatalytic properties, NO _x and SO _x gases were reduced by 90.9% and 92.8%, respectively, under ultraviolet light. TiO ₂ NPs were mixed with epoxy to maintain stable NO _x gas reduction characteristics even after continuous repeated cleaning. The epoxy-TiO ₂ -embedded high-strength functional LWA proposed in the present invention has excellent strength and durability as well as air pollution reduction functionality, so it can be expected to be widely applied to the multifunctional lightweight aggregate concrete field.

The preferred embodiment of the present invention has been described in detail above. The description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains will understand that other specific forms can be easily modified without changing the technical spirit or essential features of the present invention.

Accordingly, the scope of the present invention is indicated by the claims described below rather than the above detailed description, and all changes or modifications derived from the meaning, scope, and equivalent concept of the claims are included in the scope of the present invention. should be interpreted

Claims (10)

A high-strength lightweight aggregate in which a hyper-crosslinked polymer in which a chain network is formed by chemical reaction with a crosslinker in the lightweight aggregate having internal pores is coated on the internal pores and external surfaces of the lightweight aggregate. The method of claim 1,
The hyper-occlusion polymer is a high-strength lightweight aggregate, characterized in that it increases the mechanical strength and gas permeability in the pores of the lightweight aggregate. The method of claim 1,
The polymer is an epoxy resin, and the crosslinking agent is a high-strength lightweight aggregate, characterized in that triethylenetetramine (TETA). The method of claim 1,
A high-strength lightweight aggregate, characterized in that it is coated with photocatalytic inorganic particles. 5. The method of claim 4,
The inorganic particles are TiO ₂ High-strength lightweight aggregate, characterized in that the nanoparticles. A mixed solution containing a crosslinker and a monomer or oligomer that reacts with the crosslinker to form a hyper-crosslinked polymer of a chain network is mixed with a light weight having internal pores High-strength lightweight aggregate manufacturing method comprising; embedding in the aggregate. 7. The method of claim 6,
The embedding is a high-strength lightweight aggregate manufacturing method, characterized in that performed under negative pressure conditions. 7. The method of claim 6,
The high-strength lightweight aggregate manufacturing method, characterized in that the crosslinking agent is used in an amount of 10 to 40 parts by weight based on 100 parts by weight of the monomer or oligomer. 7. The method of claim 6,
The mixed solution contains water or alcohol, and the concentration of the monomer or oligomer is 6 to 12% by weight. 7. The method of claim 6,
The mixed solution further comprises photocatalytic inorganic particles, high-strength lightweight aggregate manufacturing method.

Images