High-salt-corrosion-resistant concrete pouring material and preparation method thereof

Abstract

The invention discloses a high-salt-corrosion-resistant concrete pouring material and a preparation method thereof, and relates to the technical field of high-salt-corrosion-resistant concrete, and the high-salt-corrosion-resistant concrete pouring material comprises the following components in parts by weight: 5-10 parts of modified charcoal, 1.5-3 parts of a corrosion inhibitor, 320-360 parts of cement, 650-700 parts of river sand, 20-30 parts of silica fume, 0.3-0.6 part of super absorbent resin, and 0.2-0.8 part of a water reducing agent. According to the high-salt-corrosion-resistant concrete pouring material and the preparation method thereof, a protective film is formed on the surface of a reinforcing steel bar through the corrosion inhibitor, the anodic oxidation reaction is inhibited, the reinforcing steel bar is prevented from being corroded, eugenol releases corrosion inhibition molecules, a hydrophobic protective film is formed on the surface of the reinforcing steel bar, and electrochemical corrosion is inhibited; meanwhile, through the synergistic effect of a physical barrier and chemical passivation, the calcium-aluminum salt-eugenol composite corrosion inhibitor not only can block a corrosion path through physical film formation, but also can inhibit electrochemical reaction through chemical adsorption, so that the corrosion inhibition efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of high-salt corrosion-resistant concrete, in particular to a high-salt corrosion-resistant concrete casting material and a preparation method thereof. Background Art

[0002] In the construction of infrastructure such as bridges, high-speed railways, and viaducts, piers are important load-bearing structures, and the performance of their concrete casting materials directly affects the quality and service life of the project.

[0003] Chinese patent publication number CN109180099A discloses a concrete material, an admixture, and a method for using the concrete material for casting pier columns. The concrete material for casting the pier columns comprises the following materials in parts by weight: 80-120 parts of Portland cement, 350-420 parts of gravel, 220-280 parts of sand, 2-26 parts of admixture, and 40-120 parts of water. The admixture comprises the following materials in parts by weight: 10-20 parts of lignin sulfonate, 50-70 parts of fly ash, 1-5 parts of calcium nitrate, 0.5-2 parts of sodium nitrite, 1-5 parts of zeolite powder, and 1-5 parts of hemp fiber. By using the admixture, the invention ensures that the concrete used for casting large pier columns has a better appearance quality and effectively avoids segregation, cracking, honeycombing, rough surfaces, voids, and bubbles. The concrete material can be used as a concrete material for pier columns of bridges, high-speed railways, viaducts, etc., and when mixed with steel bars, it also has earthquake-resistant effects.

[0004] However, as the environment in which infrastructure construction takes place becomes increasingly complex, pier column concrete materials are facing more challenges, among which corrosion resistance is a key issue. When traditional concrete materials are used in environments with corrosive media (such as acid, alkali, salt, etc.), their corrosion resistance is relatively insufficient. Chloride ions (Cl - ), sulfate (SO4 2- ) and other corrosive media can easily penetrate the pores of concrete, causing corrosion and damage to the concrete structure, thereby affecting the bearing capacity and service life of the pier column, and posing certain safety hazards; to this end, the present invention provides a high-salt corrosion-resistant concrete casting material and a preparation method thereof to solve the above-mentioned problems. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the present invention provides a high-salt corrosion-resistant concrete casting material and a preparation method thereof, which solves the problems mentioned in the above background technology.

[0006] To achieve the above objectives, the present invention is implemented through the following technical scheme: a high-salt corrosion-resistant concrete casting material, comprising the following components in parts by weight: 5-10 parts of modified biochar, 1.5-3 parts of rust inhibitor, 320-360 parts of cement, 650-700 parts of river sand, 20-30 parts of silica fume, 0.3-0.6 parts of super absorbent resin, and 0.2-0.8 parts of water reducer.

[0007] A method for preparing a concrete casting material resistant to high salt corrosion comprises the following steps:

[0008] Step 1: pre-swelling the super absorbent resin in deionized water and then draining it;

[0009] Step 2: Pour cement, silica fume, modified biochar, and rust inhibitor into a mixer, stir and mix at a speed of 500-800 r / min for 5-10 minutes, then add river sand and continue stirring for 3-5 minutes;

[0010] Step 3: Add the swollen super absorbent resin and water reducer, and stir for 10-20 minutes to obtain a concrete casting material resistant to high salt corrosion.

[0011] Preferably, the preparation method of the rust inhibitor includes the synthesis of calcium aluminum salt and chemical modification of eugenol.

[0012] Preferably, the synthesis method of the calcium aluminum salt is:

[0013] (1) Under nitrogen atmosphere, a mixed solution of 0.5 mol / L calcium nitrate tetrahydrate and 0.25 mol / L aluminum nitrate nonahydrate was evenly and slowly added dropwise to a 1.5 mol / L nitric acid solution while stirring. The temperature in a water bath was raised to 65-70°C and the reaction was carried out for 24 hours. The pH of the solution was adjusted to 10.5-11.5 with 2 mol / L sodium hydroxide.

[0014] (2) Centrifugation, the solid was washed alternately with distilled water and anhydrous ethanol for 4-6 times, and then dried at 60°C for 48 hours to obtain calcium aluminum salt.

[0015] Preferably, the chemical modification of eugenol comprises:

[0016] 1) Add 0.1 mol / L sodium hydroxide solution dropwise to eugenol and stir for 40-60 minutes to obtain product 2;

[0017] 2) Pour product 1 into product 2, stir and react at 70°C for 24-48 hours, and adjust the pH of the reaction system to 10 with 2 mol / L sodium hydroxide. Then centrifuge and wash the solid alternately with distilled water and anhydrous ethanol 4-6 times, and dry at 60°C for 48 hours.

[0018] Preferably, the amount of calcium nitrate tetrahydrate is 7.8-8.5 parts by weight, the amount of aluminum nitrate nonahydrate is 6.4-7 parts by weight, and the amount of eugenol is 1-1.6 parts by weight.

[0019] Preferably, the preparation method of the modified biochar includes high-temperature pyrolysis and alkaline activation treatment.

[0020] Preferably, the high temperature pyrolysis treatment steps are:

[0021] S11, mixing the biochar raw material after high-temperature pyrolysis with urea, pouring it into deionized water and soaking it for 10-12 hours, and then drying it at 105°C;

[0022] S12. Then place it in a tube furnace, heat it to 600-650°C at a heating rate of 10°C / min under a nitrogen atmosphere, keep it at that temperature for 45-60 minutes, and then cool it naturally to room temperature.

[0023] Preferably, the alkali activation treatment step is:

[0024] S21, placing the treated biochar in a potassium hydroxide solution, stirring for 30-40 minutes, soaking for 10-12 hours, and then drying at a constant temperature of 105°C;

[0025] S22, then put it into a tube furnace, heat it to 700-800°C at a heating rate of 5°C / min under a nitrogen atmosphere, keep it at that temperature for 1-1.5 hours, and then cool it naturally to room temperature;

[0026] S23, after washing with diluted hydrochloric acid solution 5 times, then washing with deionized water until the pH value is 7, and drying at 105℃

[0027] Preferably, in S1, the biochar raw materials are selected from two or more of pine nut shells, coconut shells, and sugarcane bagasse;

[0028] The mass of the biochar raw material is 20%-30% of the mass of urea; the mass of the potassium hydroxide solution is 200%-250% of the sum of the mass of the biochar raw material and urea;

[0029] In S2 and S4, the nitrogen flow rate is 100 mL / min.

[0030] Beneficial effects

[0031] The present invention provides a high-salt corrosion-resistant concrete casting material and a preparation method thereof. Compared with the prior art, it has the following advantages:

[0032] (1) The high-salt corrosion-resistant concrete casting material and its preparation method form a protective film on the surface of the steel bar through the rust inhibitor, inhibiting the anodic oxidation reaction and preventing the steel bar from rusting. Eugenol releases corrosion-inhibiting molecules to form a hydrophobic protective film on the surface of the steel bar to inhibit electrochemical corrosion. At the same time, the calcium aluminum salt-eugenol composite rust inhibitor can block the corrosion path through physical film formation and inhibit electrochemical reaction through chemical adsorption through the synergistic effect of physical barrier and chemical passivation, thereby improving the rust inhibition efficiency.

[0033] (2) The high-salt corrosion-resistant concrete casting material and its preparation method. The modified biochar has a rich pore structure and a huge specific surface area. It can adsorb corrosive ions such as chloride ions and sulfate ions in the salt solution, reduce their penetration into the concrete, and reduce the risk of steel corrosion. At the same time, the pore structure can form a physical barrier to hinder the migration path of salt in the concrete pores and delay the contact between the corrosive medium and the cement matrix and steel bars; and it can fill the internal pores of the concrete, improve the matrix density, reduce the connected porosity, thereby reducing the permeability coefficient of the salt solution, and interact with the cement hydration products, which may promote the formation of stable crystals such as calcium aluminate, thereby enhancing the impermeability and durability of the concrete.

[0034] In summary, this application forms a multiple protection system of "physical barrier + chemical inhibition" through the adsorption barrier of modified biochar, the chemical protection of rust inhibitors, and the density optimization of silica fume and super absorbent resin, which effectively resists the corrosion of salts such as sodium chloride and sulfate on concrete and steel bars. While improving the corrosion resistance, each component ensures that the strength, impermeability, freeze-thaw resistance and other durability of concrete are improved simultaneously by improving the microstructure and working performance. It is suitable for harsh environments such as marine engineering and saline-alkali land construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a comparison chart of the freeze-thaw resistance test provided by the present invention. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] Super absorbent resin: It is prepared by reverse suspension polymerization using 50% acrylic acid and 50% acrylamide as monomers and 0.001% methylene bisacrylamide (MBA) as a cross-linking agent. The average particle size is 141μm.

[0038] Water reducer: Chongqing Weiguan New Material Technology Co., Ltd.

[0039] Example 1

[0040] Step 1: pre-swell 0.3 kg of super absorbent resin in deionized water and drain;

[0041] The preparation method of the rust inhibitor is as follows: under a nitrogen atmosphere, a mixed solution of 7.8 g of 0.5 mol / L calcium nitrate tetrahydrate and 6.4 g of 0.25 mol / L aluminum nitrate nonahydrate is evenly and slowly added dropwise to a 1.5 mol / L nitric acid solution while stirring, the temperature is raised to 65° C. in a water bath, the reaction is carried out for 24 hours, and the pH of the solution system is adjusted to 10.5 with 2 mol / L sodium hydroxide; the mixture is centrifuged, the solid is washed alternately with distilled water and anhydrous ethanol four times, and then dried at 60° C. for 48 hours to obtain product one; 0.1 mol / L sodium hydroxide solution is added dropwise to 1 g of eugenol, the reaction is stirred for 40 minutes, and product two is obtained; product one is poured into product two, the pH value of the reaction system is adjusted to 10 with 2 mol / L sodium hydroxide, the reaction is stirred at 70° C. for 24 hours, and then centrifuged, the solid is washed alternately with distilled water and anhydrous ethanol four times, and then dried at 60° C. for 48 hours to obtain the rust inhibitor;

[0042] The modified biochar was prepared as follows: 4 g of pine nut shells, coconut shells, and sugarcane bagasse after high-temperature pyrolysis were mixed with 20 g of urea, poured into deionized water and soaked for 10 h, and then dried at 105 °C; then placed in a tube furnace, heated at a heating rate of 10 °C / min to 600 °C under a nitrogen atmosphere (flow rate 100 mL / min), kept warm for 45 min, and then naturally cooled to room temperature; placed in 52 g of potassium hydroxide solution, stirred for 30 min, soaked for 10 h, and then dried at a constant temperature of 105 °C; then placed in a tube furnace, heated at a heating rate of 5 °C / min to 700 °C under a nitrogen atmosphere (flow rate 100 mL / min), kept warm for 1 h, and then naturally cooled to room temperature; after washing with a diluted hydrochloric acid solution five times, washed with deionized water to a pH of 7, and dried at 105 °C;

[0043] Step 2: Pour 320g cement, 30kg silica fume, 10kg modified biochar, and 3kg rust inhibitor into a mixer, stir and mix at 500r / min for 5 minutes, then add 700kg river sand and continue stirring for 3 minutes;

[0044] Step 3: Add the swollen super absorbent resin and water reducer, and stir for 10 minutes to obtain a concrete casting material resistant to high salt corrosion.

[0045] Example 2

[0046] Step 1: pre-swell 0.5 kg of super absorbent resin in deionized water and drain;

[0047] The preparation method of the rust inhibitor is as follows: under a nitrogen atmosphere, a mixed solution of 8 g of 0.5 mol / L calcium nitrate tetrahydrate and 6.7 g of 0.25 mol / L aluminum nitrate nonahydrate is evenly and slowly added dropwise to a 1.5 mol / L nitric acid solution while stirring, the temperature is raised to 68° C. in a water bath, the reaction is carried out for 24 hours, and the pH of the solution system is adjusted to 11 with 2 mol / L sodium hydroxide; the mixture is centrifuged, the solid is washed alternately with distilled water and anhydrous ethanol 5 times, and then dried at 60° C. for 48 hours to obtain product one; 0.1 mol / L sodium hydroxide solution is added dropwise to 1.3 g of eugenol, and the mixture is stirred for reaction for 50 minutes to obtain product two; product one is poured into product two, the pH value of the reaction system is adjusted to 10 with 2 mol / L sodium hydroxide, the reaction is stirred at 70° C. for 36 hours, and then centrifuged, the solid is washed alternately with distilled water and anhydrous ethanol 5 times, and then dried at 60° C. for 48 hours to obtain the rust inhibitor;

[0048] The modified biochar was prepared as follows: 5 g of pine nut shells, coconut shells, and sugarcane bagasse after high-temperature pyrolysis were mixed with 20 g of urea, poured into deionized water and soaked for 11 hours, and then dried at 105°C; then placed in a tube furnace, heated at a heating rate of 10°C / min to 630°C under a nitrogen atmosphere (flow rate 100 mL / min), kept warm for 50 minutes, and then naturally cooled to room temperature; placed in 55 g of potassium hydroxide solution, stirred for 35 minutes, soaked for 11 hours, and then dried at a constant temperature of 105°C; then placed in a tube furnace, heated at a heating rate of 5°C / min to 750°C under a nitrogen atmosphere (flow rate 100 mL / min), kept warm for 1.2 hours, and then naturally cooled to room temperature; after washing with a diluted hydrochloric acid solution five times, washed with deionized water to a pH of 7, and dried at 105°C;

[0049] Step 2: Pour 340kg of cement, 25kg of silica fume, 8kg of modified biochar, and 2.2kg of rust inhibitor into a mixer, stir and mix at a speed of 600r / min for 8 minutes, then add 680kg of river sand and continue stirring for 4 minutes;

[0050] Step 3: Add the swollen super absorbent resin and water reducer, and stir for 15 minutes to obtain a concrete casting material resistant to high salt corrosion.

[0051] Example 3

[0052] Step 1: pre-swell 0.6 kg of super absorbent resin in deionized water and drain;

[0053] The preparation method of the rust inhibitor is as follows: under a nitrogen atmosphere, a mixed solution of 8.5 g of 0.5 mol / L calcium nitrate tetrahydrate and 7 g of 0.25 mol / L aluminum nitrate nonahydrate is evenly and slowly added dropwise to a 1.5 mol / L nitric acid solution while stirring, the mixture is heated to 70° C. in a water bath, reacted for 24 hours, and the pH of the solution system is adjusted to 11.5 with 2 mol / L sodium hydroxide; the mixture is centrifuged, the solid is washed alternately with distilled water and anhydrous ethanol 6 times, and dried at 60° C. for 48 hours to obtain product one; 0.1 mol / L sodium hydroxide solution is added dropwise to 1.6 g of eugenol, and the mixture is stirred for reaction for 60 minutes to obtain product two; product one is poured into product two, the pH value of the reaction system is adjusted to 10 with 2 mol / L sodium hydroxide, the reaction is stirred at 70° C. for 48 hours, and then centrifuged, the solid is washed alternately with distilled water and anhydrous ethanol 6 times, and dried at 60° C. for 48 hours to obtain the rust inhibitor;

[0054] The modified biochar was prepared as follows: 6 g of pine nut shells, coconut shells, and sugarcane bagasse after high-temperature pyrolysis were mixed with 20 g of urea, poured into deionized water and soaked for 12 h, and then dried at 105 ° C. The mixture was then placed in a tube furnace and heated to 650 ° C at a heating rate of 10 ° C / min under a nitrogen atmosphere (flow rate 100 mL / min), kept warm for 60 min, and then naturally cooled to room temperature; the mixture was placed in 65 g of potassium hydroxide solution, stirred for 40 min, soaked for 12 h, and then dried at a constant temperature of 105 ° C. The mixture was then placed in a tube furnace and heated to 800 ° C at a heating rate of 5 ° C / min under a nitrogen atmosphere (flow rate 100 mL / min), kept warm for 1.5 h, and then naturally cooled to room temperature; the mixture was washed with a diluted hydrochloric acid solution five times, then washed with deionized water to a pH of 7, and dried at 105 ° C.

[0055] Step 2: Pour 360kg of cement, 20kg of silica fume, 5kg of modified biochar, and 1.5kg of rust inhibitor into a mixer, stir and mix at a speed of 800r / min for 10 minutes, then add 650kg of river sand and continue stirring for 5 minutes;

[0056] Step 3: Add the swollen super absorbent resin and water reducer, and stir for 20 minutes to obtain a concrete casting material resistant to high salt corrosion.

[0057] Comparative Example 1

[0058] Compared with Example 1, the difference is that no modified biochar is added; the rest remains unchanged.

[0059] Comparative Example 2

[0060] Compared with Example 1, the difference is that no rust inhibitor is added; the rest remains unchanged.

[0061] Sulfate corrosion resistance test: Referring to GB / T 50082-2024, the specimens were immersed in a 5% Na2SO4 solution (pH 6-8) and subjected to a dry-wet cycle. The specimens were first immersed in the solution at 20±2°C for 16 hours, then dried in an 80°C oven for 6 hours and cooled for 1 hour. This constituted one cycle. After 20 cycles, the mass loss rate was calculated. The results are shown in Table 1.

[0062] Chloride ion penetration resistance test: According to GB / T50082-2024, the concrete was made into a cylindrical specimen of Ø100×50mm, a voltage of 30V was applied, the chloride ion migration depth was tested, and the diffusion coefficient dRCM (×10 -12 m² / s); the results are shown in Table 1.

[0063] Table 1

[0064] Mass loss rate / % <![CDATA[dRCM(×10 -12 m² / s)]]> Example 1 2.85 2.8 Example 2 3.42 3.1 Example 3 3.75 3.4 Comparative Example 1 5.47 6.02 Comparative Example 2 5.21 5.73

[0065] Freeze-thaw resistance test: refer to GB / T 50082-2024, after 150 freeze-thaw cycles, the results are as follows Figure 1 As shown in FIG1 , the concrete materials prepared in Examples 1-3 have significantly improved freeze-thaw resistance compared to Comparative Examples 1-2.

[0066] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0067] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0068] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A concrete casting material resistant to high salt corrosion, characterized in that: The invention comprises the following components in parts by weight: 5-10 parts of modified biochar, 1.5-3 parts of rust inhibitor, 320-360 parts of cement, 650-700 parts of river sand, 20-30 parts of silica fume, 0.3-0.6 parts of highly absorbent resin and 0.2-0.8 parts of water reducing agent.

2. A method for preparing a high-salt corrosion-resistant concrete casting material according to claim 1, characterized in that: The method comprises the following preparation steps: Step 1: pre-swelling the super absorbent resin in deionized water and then draining it; Step 2: Pour cement, silica fume, modified biochar, and rust inhibitor into a mixer, stir and mix at a speed of 500-800 r / min for 5-10 minutes, then add river sand and continue stirring for 3-5 minutes; Step 3: Add the swollen super absorbent resin and water reducer, and stir for 10-20 minutes to obtain a concrete casting material resistant to high salt corrosion.

3. The method for preparing a high-salt corrosion-resistant concrete casting material according to claim 2, characterized in that: The preparation method of the rust inhibitor comprises the synthesis of calcium aluminum salt and chemical modification of eugenol.

4. The method for preparing a high-salt corrosion-resistant concrete casting material according to claim 3, characterized in that: The synthesis method of the calcium aluminum salt is: (1) Under nitrogen atmosphere, a mixed solution of 0.5 mol / L calcium nitrate tetrahydrate and 0.25 mol / L aluminum nitrate nonahydrate was evenly and slowly added dropwise to a 1.5 mol / L nitric acid solution while stirring. The temperature in a water bath was raised to 65-70°C and the reaction was carried out for 24 hours. The pH of the solution was adjusted to 10.5-11.5 with 2 mol / L sodium hydroxide. (2) Centrifugation, the solid was washed alternately with distilled water and anhydrous ethanol for 4-6 times, and then dried at 60°C for 48 hours to obtain calcium aluminum salt.

5. The method for preparing a high-salt corrosion-resistant concrete casting material according to claim 4, characterized in that: The chemical modification of the eugenol comprises: 1) Add 0.1 mol / L sodium hydroxide solution dropwise to eugenol and stir for 40-60 minutes to obtain product 2; 2) Pour product 1 into product 2, stir and react at 70°C for 24-48 hours, and adjust the pH of the reaction system to 10 with 2 mol / L sodium hydroxide. Then centrifuge and wash the solid alternately with distilled water and anhydrous ethanol 4-6 times, and dry at 60°C for 48 hours.

6. The method for preparing a high-salt corrosion-resistant concrete casting material according to claim 5, characterized in that: in, The amount of calcium nitrate tetrahydrate is 7.8-8.5 parts by weight, the amount of aluminum nitrate nonahydrate is 6.4-7 parts by weight, and the amount of eugenol is 1-1.6 parts by weight.

7. The method for preparing a high-salt corrosion-resistant concrete casting material according to claim 2, characterized in that: The preparation method of the modified biochar includes high-temperature pyrolysis and alkali activation treatment.

8. The method for preparing a high-salt corrosion-resistant concrete casting material according to claim 7, characterized in that: The processing steps of the high temperature pyrolysis are: S11, mixing the biochar raw material after high-temperature pyrolysis with urea, pouring it into deionized water and soaking it for 10-12 hours, and then drying it at 105°C; S12. Then place it in a tube furnace, heat it to 600-650°C at a heating rate of 10°C / min under a nitrogen atmosphere, keep it at that temperature for 45-60 minutes, and then cool it naturally to room temperature.

9. The method for preparing a high-salt corrosion-resistant concrete casting material according to claim 8, characterized in that: The alkali activation treatment steps are: S21, placing the treated biochar in a potassium hydroxide solution, stirring for 30-40 minutes, soaking for 10-12 hours, and then drying at a constant temperature of 105°C; S22, then put it into a tube furnace, heat it to 700-800°C at a heating rate of 5°C / min under a nitrogen atmosphere, keep it at that temperature for 1-1.5 hours, and then cool it naturally to room temperature; S23. Wash with diluted hydrochloric acid solution 5 times, then wash with deionized water until the pH value is 7, and dry at 105°C.

10. The method for preparing a high-salt corrosion-resistant concrete casting material according to claim 7, characterized in that: In S1, the biochar raw materials are selected from two or more of pine nut shells, coconut shells, and sugarcane bagasse; The mass of the biochar raw material is 20%-30% of the mass of urea; the mass of the potassium hydroxide solution is 200%-250% of the sum of the mass of the biochar raw material and urea; In S2 and S4, the nitrogen flow rate is 100 mL / min.

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