Eco-friendly concrete composition and manufacturing method thereof

Abstract

The present invention relates to an eco-friendly concrete composition comprising cellulose nanogels obtained from bur cucumber and bagasse, and a manufacturing method thereof.

Description

Eco-friendly concrete composition and method for manufacturing the same

[0001] The present invention relates to an eco-friendly concrete composition and a method for producing the same.

[0002] Nanocellulose, an organic polymer with excellent tensile strength, is attracting attention as an eco-friendly, next-generation material that could replace organic binders. However, due to its high manufacturing costs, nanocellulose is currently limited to medical, optical, and cosmetic applications. Consequently, its widespread application in general industrial applications is hindered.

[0003] While nanocellulose is not currently produced on an industrial scale, it can be extracted from cellulose-containing materials through various methods, broadly categorized into mechanical, chemical, and biological methods. Chemical methods use acids or enzymes to hydrolyze the cellulose macromolecules. Mechanical methods involve breaking hydrogen bonds within cellulose with strong physical energy. Biological methods are produced by bacterial species. Mechanical methods shorten and split cellulose fibers using shredding, allowing the production of cellulose fibers ranging from a few micrometers in diameter and length to tens of nanometers in diameter and length.

[0004] Although there is currently no technology for industrial-scale application of nanocellulose in construction mortar and concrete, many recent studies have focused on strengthening concrete and cement paste. Nanocellulose can be manufactured in gel and powder forms and is insoluble in water, allowing various types of nanocellulose to be mixed with cement. Examples include wood-derived CNC, carrot-derived CNC, acid hydrolyzed microcellulose, nanocellulose extracted from wood processing waste, and microbial cellulose. It has been reported that mixing nanocellulose with Portland cement, mortar powder, calcium aluminate cement (CAC) paste, and ordinary Portland cement (OPC) paste at a ratio of 0.04–1.15% can increase the concrete strength by an average of 0.1–0.8% (Danuta Barnat-Hunek et al. 2019; Aofei Guo et al. 2020). Increasing the mixing ratio of wood-based nanocellulose to 0.5-2% of the cement content helps increase the compressive strength by 13% and the flexural strength by 12%, respectively, but does not significantly affect the tensile strength of concrete. Cement containing cellulose nanocrystals (CNCs) can increase the specific gravity, reduce the absorption of cementitious materials, and delay the hydration of the cement, but the hydration level increases after a certain period of time. Even small additions of CNC can improve mechanical strength, but using high CNC mixing ratios can be counterproductive. CNC can increase the density of concrete blocks by reducing air voids and reduce drying shrinkage, but above a certain threshold, it can increase the depth of carbonation and reduce chloride ion penetration, but it is susceptible to the harmful effects of some resistant freeze / thaw degradation.

[0005] For cementitious materials containing cellulose nanofibers (CNF), studies have shown that CNF can reduce fluidity, act as a viscosity modifier, increase the specific gravity of cement, and reduce water absorption, but also increase thermal conductivity and thermal expansion. Furthermore, CNF can delay the onset of cement hydration, thereby increasing the level of hydration once a certain service life has been achieved. While small additions of CNF can improve mechanical properties, excessive additions can be counterproductive. CNF is effective in controlling capillary size in block concrete, but there are inconsistent conclusions regarding its effect on porosity. Furthermore, CNF can reduce free and autogenous shrinkage, improve the surface tension and viscosity of cement paste, reduce the penetration of sulfate and chloride ions, and enhance freeze / thaw resistance.

[0006] In cementitious materials containing microbial cellulose (BC), BC is believed to act as a nano-crosslinker, reducing water absorption, improving mechanical properties, and preventing nano-curling. BC is known to have minimal effect on the hydroxylation, shrinkage, rheology, and durability of cementitious materials.

[0007] For comparison, cements containing cellulose fibers (CF) have also been studied. CF can reduce fluidity, increase air content, increase specific life, and improve mechanical properties, but without significant changes. CF can reinforce the transition zone (ITZ) between cement paste and aggregate, and can also increase flow stress and alter viscosity. CF is also known to have little effect on the shrinkage and durability of cementitious materials.

[0008] Meanwhile, one of the reasons for the high manufacturing costs of chemical methods is the acid hydrolysis process of cellulose. Nickerson first used sulfuric acid in the early 1940s and it has been commonly used since then. Sulfuric acid hydrolysis forms a highly stable reaction system with a high negative charge due to the bonding of sulfuric acid ester groups on the surface of crystalline materials. However, the low-temperature, concentrated sulfuric acid hydrolysis method yields low cellulose (Bondeson et al. (2009), Sharma et al. (2012)), which limits its use in large-scale industrial nanocellulose production. For example, Bondeson et al. (2006) reported that acid hydrolysis of cellulose yielded only about 30% nanocellulose from microcrystalline cellulose, and even lower yields were reported for other raw materials. For example, the yield of nanocellulose is 0.0256% in rye (Sharma et al. (2012)) and 16.9% in rice straw (Jiang & Hsieh, 2013). In addition, the use of high-concentration acid (~60%) with a large consumption inevitably has limitations in application even on a laboratory scale. Patent Document 1 discloses a process for manufacturing nanocellulose in the form of cellulose powder, specifically, a method for obtaining nanocellulose powder with a diameter of 100 to 200 nm through processes such as hydrolysis (5 hours, using sulfuric acid (concentration: 45%), 40 degrees), filtering the recovered solution, adding it to a buffer solution to neutralize the pH to 7, centrifugal filtration, washing, and drying.In Patent Document 1, the acid solution absorbed into nanocellulose is effectively neutralized with NH3 or NH4Cl, and the hydrogen bonds on the surface are destroyed, so that the resulting powdered nanocellulose can easily form a stable colloid in water without clumping when dried, and the buffer solution is inexpensive and readily available, and can be applied under mild reaction conditions, so it has the advantage of being applicable on an industrial scale. However, Patent Document 1 has the problem that not only is there a risk in handling because it uses high-concentration sulfuric acid, but it is also highly corrosive, which limits the reactor or process, and there are also environmental problems due to the waste after the reaction.

[0009] Mechanical homogenization, first developed by Turbak et al. in 1980, produces nanocellulose with longer fiber lengths and better fiber cohesion, resulting in cellulose nanogels with stronger gelation. However, it tends to destroy the microfiber structure, resulting in lower molecular weight and crystallinity of the resulting nanocellulose. Furthermore, mechanical homogenization consumes a large amount of power, resulting in a low zeta potential (-10 mV) (Stenstad et al. 2008). Therefore, a method that combines chemical and mechanical methods to enhance the manufacturing process of nanocellulose is needed.

[0010] Patent Documents 2 and 3 disclose processes that combine chemical and mechanical methods. In the chemical method, TEMPO (a mixture of NaBr and NaClO), which is used as a pretreatment agent, oxidizes hydroxyl functional groups when reacting with cellulose and forms a carboxylic acid group at the C6 position of the glucopyranose monomer, allowing cellulose fibers to be easily separated from each other during grinding. Patent Document 2 discloses that the pretreatment reduces grinding energy consumption when using lignocellulosic cellulose powder as a raw material, and Patent Document 3 discloses that the pretreatment increases the yield of nanocellulose. However, Patent Documents 2 and 3 have problems in that the yield of nanocellulose is low at 19.7% when nanocellulose is extracted from non-lignified raw materials, the high price of TEMPO increases manufacturing costs, and TEMPO not only interferes with the cellulose purification process but also causes environmental problems due to waste.

[0011] Biological methods, first studied and used by Henriksson et al. (European Polymer Journal, 43), are more environmentally friendly than chemical methods using acid treatment. They increase the reactivity and swelling of cellulose fibers, resulting in nanocellulose with higher average specific gravity and shrinkage. However, their use has been limited by the low zeta potential (-1.5-2 mV) and low efficiency (~12.3%) of nanocellulose.

[0012] Additionally, the use of strong acids makes it difficult to utilize the byproducts generated during manufacturing. Therefore, a safer, more efficient, and economical method for obtaining nanocellulose is needed.

[0013] The purpose of the present invention is to solve the above-described problems, and to provide a composition of eco-friendly concrete and a method for producing the same, which secures process stability by obtaining cellulose from thornbush and bagasse and applying a weak acid during hydrolysis, and is eco-friendly while increasing yield compared to the conventional method and reducing manufacturing cost.

[0014] To achieve the above purpose, an eco-friendly concrete composition according to one embodiment of the present invention includes cellulose nanogel obtained from thornbush and bagasse.

[0015] In order to achieve the above purpose, a method for manufacturing eco-friendly concrete according to another embodiment of the present invention comprises the steps of (a) obtaining cellulose nanogel from thornbush and bagasse, and (b) mixing the cellulose nanogel manufactured in step (a) with a cement mixture.

[0016] In addition, the step (a) may include (a-1) a step of separating cellulose from thorns and bagasse and then washing it with a neutral solution, (a-2) a step of first bleaching the cellulose with a sodium hydroxide solution and a hydrogen peroxide solution and then neutralizing it, (a-3) a step of treating the cellulose neutralized in the step (a-2) with a hydrogen peroxide and sulfuric acid solution to hydrolyze it and then neutralize it, (a-4) a step of second bleaching the cellulose neutralized in the step (a-3) with a sodium hydroxide solution and a hydrogen peroxide solution and then neutralizing it and compressing it, and (a-5) a step of diluting the compressed cellulose and then pulverizing it to prepare a cellulose nanogel.

[0017] According to one embodiment of the present invention, by replacing a portion of the cement with cellulose nanogel obtained from bagasse and burdock, the strength of concrete can be improved compared to conventional concrete while contributing to environmental protection.

[0018] In addition, according to another embodiment of the present invention, by treating with weak acid and low temperature to hydrolyze, by-products and waste generated during manufacturing can be utilized immediately without a separate treatment process, thereby providing an economical and environmentally friendly effect.

[0019] In addition, according to another embodiment of the present invention, the yield of cellulose can be increased by obtaining cellulose nanogel from bagasse and thornbush.

[0020] Figure 1 is a process diagram for explaining a method for manufacturing eco-friendly concrete according to one embodiment of the present invention.

[0021] Figure 2 is a process diagram explaining a method for manufacturing cellulose nanogel.

[0022] Hereinafter, the present invention will be described in detail with reference to embodiments illustrated in the accompanying drawings. However, the present invention is not limited to the illustrated embodiments. The above and other objectives and novel features of the present invention will become more apparent through the description of this specification and the accompanying drawings.

[0023]

[0024] Hereinafter, an eco-friendly concrete composition according to one embodiment of the present invention will be described in detail.

[0025] An eco-friendly concrete composition according to one embodiment of the present invention may include cellulose nanogel obtained from thornbush and bagasse, wherein the cellulose nanogel may be prepared by two bleaching processes and acid hydrolysis.

[0026] For example, cellulose nanogels can be natural nanomaterials that are light yellow in color, have a viscosity of about 300 mP.s, a length of less than 1.0 um, and a diameter of less than 200 nm, for example, less than 100 nm. Cellulose nanogels have excellent flexibility and deformability, gel or thick suspension forming properties, a higher viscosity than cellulose, a decrease in viscosity when stirred, and a tendency to return to their original state when not stirred.

[0027] Meanwhile, the concrete according to the present embodiment can exhibit better biodegradability than concrete that does not include cellulose nanogel by replacing a portion of the cement with cellulose nanogel, and can satisfy the range of flexural strength of 18.5 to 20 MPa and compressive strength of 86 to 89 MPa after 28 days of curing, which can be values ​​that are 7 to 13% improved in flexural strength and 8 to 10% improved in compressive strength compared to conventional concrete.

[0028] In this example, bagasse is the residue discarded after sugarcane is extracted from sugarcane by sugar companies, and Sicyos angulatus is a notorious plant that was designated as an invasive species by the Ministry of Environment of the Republic of Korea on June 1, 2009. By recycling these bagasse and Sicyos angulatus as building materials, it is possible to contribute to environmental protection while also improving the strength of concrete compared to before.

[0029]

[0030] Hereinafter, a method for manufacturing eco-friendly concrete according to another embodiment of the present invention will be described in detail with reference to drawings.

[0031] FIG. 1 is a process diagram for explaining a method for manufacturing eco-friendly concrete according to one embodiment of the present invention, and FIG. 2 is a process diagram for explaining a method for manufacturing cellulose nanogel.

[0032] Referring to FIGS. 1 and 2, cellulose nanogel is obtained from thornbush and bagasse (S10).

[0033] After separating cellulose from the thorns and bagasse, it is washed with a neutral solution (S11).

[0034] After adding 700 to 900 parts by weight of a sodium hydroxide solution having a concentration of 1 to 13%, for example, 12 to 13%, to 100 parts by weight of thorn pulp and bagasse, stirring is performed in a closed or open equipment at 90 to 110°C for 120 to 150 minutes, for example, 150 minutes, to separate low-purity cellulose from the thorn pulp and bagasse, and then washing with a neutral solution, i.e., industrial water, three or more times, and pressing to a moisture content of 20 to 25%. In this embodiment, the solid-liquid ratio of bagasse may be 1:7 to 9, and it is preferable that the neutral solution used as washing water in the first time be recovered and used as washing water in the second and third times, and of course, lignin can be separated from the washing water used and recovered and added to the production of concrete.

[0035] In this embodiment, bagasse (sugarcane waste) is collected from sugarcane residues discarded after extracting sugar from sugarcane at a sugar refinery and dried to a moisture content of 15% or less, for example, 12-14%. This can increase process efficiency. If the moisture content is 0%, the yield is good, but since a lot of energy is required to remove moisture, not only may process efficiency decrease but also manufacturing costs may increase. Sicyos angulatus can be used alone or in a mixture of fresh and dried states, and its use state is not significantly restricted.

[0036]

[0037] Then, the cellulose is first bleached with a sodium hydroxide solution and a hydrogen peroxide solution and then neutralized (S12).

[0038] In the above step S11, 100 parts by weight of the washed cellulose is added with 1 to 3 parts by weight of a 1 to 10% sodium hydroxide solution, 3 to 5 parts by weight of a 20 to 30% hydrogen peroxide solution, and 992 to 996 parts by weight of water, and primary bleaching is performed at 70 to 90°C for 100 to 150 minutes, and then the solution is washed several times with a neutral solution, i.e., industrial water, until the pH becomes 7 to neutralize, and pressed to a moisture content of 20 to 25%. In this embodiment, the solid-liquid ratio of the cellulose may be 1: 9 to 10, and if the temperature and time are exceeded, it is difficult to properly remove the residual lignin and the quality may deteriorate. Meanwhile, since the cellulose contains a relatively large amount of impurities during the primary bleaching, it is preferable to use a larger amount of hydrogen peroxide solution compared to the secondary bleaching step described below.

[0039]

[0040] Afterwards, the neutralized cellulose is treated with hydrogen peroxide and sulfuric acid solution to hydrolyze and then neutralize (S13).

[0041] In the above step S12, 100 parts by weight of neutralized cellulose is treated with 800 to 1000 parts by weight of a solution of hydrogen peroxide having a concentration of 0.5 to 0.7% and sulfuric acid having a concentration of 0.4 to 0.6% at 120 to 180°C, for example, 140 to 160°C, for 120 to 180 minutes, for example, 140 to 160 minutes, to hydrolyze the cellulose, and then washed several times with a neutral solution, i.e., industrial water, until the pH becomes 7, thereby neutralizing the cellulose. In this embodiment, the solid-liquid ratio of the neutralized cellulose may be 1:8 to 10, and it may take 25 to 35 minutes, for example, 30 minutes, to heat from room temperature to the highest temperature, and after the temperature is maintained, the powder may be removed. If the above temperature is less than 140°C, it may be difficult to secure the tensile strength required in the art, and if it exceeds 160°C, small-sized nanocellulose may be obtained with high purity, but the yield may be low.

[0042] Through hydrolysis, macroscopic or microscopic cellulose can undergo cleavage across the amorphous region to produce rod-shaped materials called cellulose nanocrystals, which have a high surface area, 1.50 g / cm 3 It can have a low density below and a high tensile strength of 20 MPa or more.

[0043] As described above, in this embodiment, by treating a low-concentration sulfuric acid solution at a low temperature, the cleaning process is easy, process stability is secured, and environmental friendliness is maintained while reducing manufacturing costs compared to conventional methods. Furthermore, since byproducts generated during manufacturing due to the weak acid treatment can be utilized immediately without additional treatment, the process is both economical and environmentally friendly.

[0044] For example, cellulose obtained through a sulfuric acid solution may be well dispersed in water and may not have a time-dependent viscosity.

[0045]

[0046] Then, the neutralized cellulose is bleached a second time with a sodium hydroxide solution and a hydrogen peroxide solution, and then neutralized and pressed (S14).

[0047] In the above step S13, 100 parts by weight of the neutralized cellulose is added with 1 to 3 parts by weight of a 1 to 10% sodium hydroxide solution, 1 to 3 parts by weight of a 20 to 30% hydrogen peroxide solution, and 994 to 998 parts by weight of water, and secondary bleaching is performed at 70 to 90°C for 40 to 80 minutes. After that, the solution is washed several times with a neutral solution, i.e., industrial water, until the pH becomes 7, thereby neutralizing, and can be pressed until the moisture content becomes 20 to 25%. In this embodiment, the solid-liquid ratio of the neutralized cellulose may be 1:9 to 10, and if the temperature and time mentioned above are exceeded, it is difficult to properly remove the residual lignin and the quality may deteriorate. In the first bleaching step, cellulose is partially bleached in addition to hydrolysis, so the second bleaching step can be performed with a lower content of hydrogen peroxide solution, thereby further saving cost and time.

[0048]

[0049] Finally, the compressed cellulose is diluted and then pulverized to produce cellulose nanogel (S15).

[0050] In the above step S14, the compressed cellulose is diluted to a concentration of 10% and then ground with a shear mill for 1 to 3 minutes to produce a homogeneous cellulose nanogel with a concentration of 10 to 12%.

[0051] For example, the yield of cellulose nanogel may be 25% or more based on the weight of the thornbush and bagasse, may be light yellow in color, have a viscosity of about 300 mP.s, have a length of less than 1.0 um, and have a diameter of less than 200 nm, for example, less than 100 nm.

[0052] In the case of cellulose using burrs and bagasse, the diameter can be relatively small because it has good homogeneity compared to cellulose synthesized from bacteria such as algae and fungi and marine animals.

[0053] Meanwhile, the alkaline wastewater generated in steps S11, S12, and S14 and the acidic wastewater generated in step S13 are mixed to produce neutral wastewater, which can be environmentally harmless. Furthermore, lignin can be recovered from wastewater generated during the manufacturing process and added to concrete.

[0054]

[0055] Then, the cellulose nanogel and cement mixture are mixed (S20).

[0056] The cellulose nanogel (NC) obtained in the above step S10 can be mixed with a cement mixture. At this time, the cellulose nanogel (NC) can be mixed in an amount of 1.0 to 2.0 parts by weight based on 100 parts by weight of cement. If the content of the cellulose nanogel (NC) is less than 1.0 parts by weight, the flexural strength and compressive strength may be low, and if it exceeds 2.0 parts by weight, the effect of the increase may not be very large.

[0057] The cement mixture may include one or more selected from cement (C), sand (S), superplastic additive (SD), crushed stone (CS), superplasticizer (SS), water (W), silica fume (SF), and fly ash (FA). Mineral additives may be further included as needed.

[0058] Cement (C) is one or more selected from among Portland cement, Portland blast furnace slag cement, Portland fly ash cement, Portland pozzolanic cement, masonry cement, dry cement mortar, silica cement, alumina cement, expanded cement, sulfate-resistant cement, and colloid cement, with a specific gravity of 3.1 g / cm 3 , the standard amount of water 31%, initial setting time 120 minutes, final setting time 210 minutes, compressive strength 22.3 MPa for 3 days, compressive strength 43.7 MPa for 28 days can be used.

[0059] Superplastic Admixture (SD) can be used, for example, Silkroad SPR3000 and ASTM C494 G type conforming to TCVN 8826:2011, and can be included in an amount of 0.1 to 1.0 parts by weight per 100 parts by weight of cement.

[0060] Silica fume (SF) is a substance added to improve durability and cracking problems, with a specific gravity of 2.4 g / cm. 3 , maximum powder residue (45um) 2.5%, average powder residue (45um) 1.0%, activity index at 7 days 105%, specific surface area 15m 2 / g, SiO2 content of 94%, moisture content of 1.2%, and weight loss during calcination of 3% can be used. Such silica fume can be included in an amount of 10 to 20 parts by weight per 100 parts by weight of cement.

[0061] Sand (S) is a substance added to ensure strength and durability, with a specific gravity of 2.65 g / cm. 3 , dry volume mass 2.46 g / cm 3 , surface saturated volume mass 2.53 g / cm 3 , foam volume mass 1.59 g / cm 3 , absorption 2.93%, dust, silt, clay content 1.5%, size factor (MdI) 2.6 can be used. Such sand can be included in an amount of 100 to 300 parts by weight per 100 parts by weight of cement.

[0062] Crushed stone (CS) is a material added to ensure strength and durability, with a specific gravity of 2.74 g / cm 3 , dry volume mass 2.71 g / cm 3 , surface saturated volume mass 2.73 g / cm 3 , foam volume mass D20 type 1395kg / m 3 , foam volume mass D10 type 1350kg / m 3, which satisfies an absorption rate of 0.4% and a dust, silt, and clay content of 0.3% can be used. Such crushed stone can be included in an amount of 150 to 300 parts by weight per 100 parts by weight of cement.

[0063] High-performance water reducing agents (SS) are substances added to enhance the functionality of general water reducing agents, effectively disperse cement, and prevent adverse effects such as delayed setting, reduced strength, and excessive air entrainment. An example is Silk Road High-Performance Water Reducer (SPR3000). This high-performance water reducing agent can be added at a concentration of 1 to 2 parts by weight per 100 parts by weight of cement.

[0064] Fly ash (FA) is a substance added to improve potential hydraulic properties, long-term strength development, and durability, with a specific gravity of 2.2 to 2.3 g / cm. 3 , moisture content of 0.6% or less, weight loss during calcination of 5.5%, and powder residue (45 um) of 23% can be used. Such fly ash can be included in an amount of 20 to 60 parts by weight per 100 parts by weight of cement, but if the content of fly ash exceeds the above-mentioned ratio, it may be difficult for the tensile strength and compressive strength to meet the range required by the industry.

[0065] Concrete manufactured by the above-described manufacturing method can reduce the amount of cement used by 10 to 12% compared to conventional concrete while improving the flexural strength and tensile strength by about 7 to 13% and the compressive strength by about 8 to 10% or achieving the same strength.

[0066]

[0067] Examples 1 and 2. Concrete production

[0068] Concrete was manufactured by mixing the composition and ratio described in Table 1 below.

[0069] The proportions are by weight.

[0070] Classification CSWSDNC Example 1100135240.71 Example 2100135240.71.5

[0071]

[0072] Examples 3 to 5. Concrete production

[0073] Concrete was manufactured by mixing the composition and ratio described in Table 2 below.

[0074] The proportions are by weight.

[0075] Classification CCSCSSSWSFFANC Example 3 100 146 219 1.3 39.7-32.9 1.3 Example 4 100 155 17 21.4 35.8 14.22 8.7 1.4 Example 5 100 190 212 1.7 5 44 17.5 5 8.31.8

[0076]

[0077] Comparative Example 1. Concrete Manufacturing

[0078] Concrete was manufactured in the same manner as in Example 1, except that cellulose nanogel (NC) was not used.

[0079]

[0080] Comparative Examples 2 to 4. Concrete Manufacturing

[0081] Concrete was manufactured by mixing the composition and ratio described in Table 3 below.

[0082] The proportions are by weight.

[0083] Classification CCSCSSSWSFFANC Comparative Example 2100268277146-25-Comparative Example 31001462191.339.7-32.9-Comparative Example 41001551721.435.814.228.7-

[0084]

[0085] Experimental Example 1. Strength Evaluation

[0086] The compressive strength (KS F 2405), flexural strength (KS F 2408), tensile strength, and slump of the concrete manufactured in Examples 1 to 6 and Comparative Examples 1 to 4 were measured, and the results are shown in Tables 4 and 5.

[0087] Classification Example 1 Example 2 Comparative Example 17-day flexural strength (MPa) 16.1 15 15.3 Compressive strength (MPa) 70.6 7 3.4 7 1.1 2 8-day flexural strength (MPa) 19.6 18.6 18.1 Compressive strength (MPa) 88.6 8 6.4 8 5.7

[0088] Referring to Table 4, it was confirmed that after 28 days when the concrete was fully hardened, Examples 1 and 2 containing cellulose nanogel had higher flexural strength and compressive strength than Comparative Example 1 not containing cellulose nanogel. When the content of cellulose nanogel was 1 wt%, the flexural strength and compressive strength were the best.

[0089] Classification Example 3 Example 4 Example 5 Comparative Example 2 Comparative Example 3 Comparative Example 4 Slump (MPa) 570 730 700 480 550 710 Tensile strength (MPa) 7.14 7.41 7.20 5.22 6.72 6.90 Compressive strength (MPa) 64.56 8.56 3.84 5.05 9.66 2.4

[0090] Referring to Table 5, the examples containing cellulose nanogel under the same conditions exhibited superior slump, tensile strength, and compressive strength. Meanwhile, Example 5, which reduced the cement content and increased the fly ash content, exhibited lower values ​​in all items compared to Example 4, but satisfied the numerical range required by the industry.

[0091]

[0092] Although exemplary embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

[0093] All technical terms used in this invention, unless otherwise defined, have the same meaning as commonly understood by those skilled in the art in the relevant field of the present invention. The contents of all publications cited as references herein are incorporated herein by reference.

Claims

1. An eco-friendly concrete composition comprising cellulose nanogel obtained from thornbush and bagasse.

2. In claim 1, The above cellulose nanogel is an eco-friendly concrete composition manufactured through two bleaching processes and acid hydrolysis.

3. In claim 1, The above composition is an eco-friendly concrete composition that satisfies the flexural strength range of 18.5 to 20 MPa and the compressive strength range of 86 to 89 MPa after curing for 28 days. 4.(a) a step of obtaining cellulose nanogel from thornbush and bagasse; and (b) A method for manufacturing eco-friendly concrete, comprising a step of mixing the cellulose nanogel obtained in step (a) with a cement mixture.

5. In claim 4, Step (a) above, (a-1) A step of separating cellulose from thorns and bagasse and then washing it with a neutral solution; (a-2) A step of neutralizing the cellulose after first bleaching it with a sodium hydroxide solution and a hydrogen peroxide solution; (a-3) A step of neutralizing the cellulose neutralized in step (a-2) by hydrolyzing it with a hydrogen peroxide and sulfuric acid solution; (a-4) A step of neutralizing and compressing the cellulose neutralized in step (a-3) by secondary bleaching with a sodium hydroxide solution and a hydrogen peroxide solution; and (a-5) A method for manufacturing eco-friendly concrete, comprising the step of diluting the compressed cellulose and then grinding it to manufacture cellulose nanogel.

6. In claim 5, A method for manufacturing eco-friendly concrete, wherein in the above step (a-2), primary bleaching is performed by adding 1 to 3 parts by weight of a 1 to 10% concentration sodium hydroxide solution and 3 to 5 parts by weight of a 20 to 30% concentration hydrogen peroxide solution to 100 parts by weight of cellulose, and performing the bleaching at 70 to 90°C for 100 to 150 minutes.

7. In claim 5, A method for manufacturing eco-friendly concrete, wherein secondary bleaching in the above step (a-4) is performed at 70 to 90°C for 40 to 80 minutes by adding 1 to 3 parts by weight of a 1 to 10% concentration sodium hydroxide solution and 1 to 3 parts by weight of a 20 to 30% concentration hydrogen peroxide solution to 100 parts by weight of neutralized cellulose.

8. In claim 5, A method for manufacturing eco-friendly concrete, wherein in the above step (a-5), the cellulose nanogel has a viscosity of 200 to 400 mP.s, a length of less than 1.0 um, and a diameter of less than 200 nm.

Images