A method for preparing a high-strength corrosion-resistant concrete

Abstract

The application discloses a preparation method of high-strength corrosion-resistant concrete, which comprises 55-64 parts of aggregate, 18-22 parts of filler, 12-18 parts of cementing agent, and 0.15-1 part of nano-silicon dioxide modified nylon fiber; the high-strength corrosion-resistant concrete is obtained through the processes of stirring, pouring, vibrating, demolding and curing; the poly(amide- imide) grafted silicon dioxide with excellent mechanical properties is added into the concrete, the silicon dioxide nylon composite fiber forms a reinforcing phase in the concrete, fills the gaps of the concrete and supports the framework, and the compressive strength of the concrete is significantly improved; and after being soaked in sulfuric acid, the concrete still maintains high compressive strength and strength retention rate.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of concrete, in particular to a preparation method of high-strength corrosion-resistant concrete. BACKGROUND

[0002] Concrete is one of the most important civil engineering materials in the contemporary era. It is widely used in the fields of roads and bridges, ocean development, and geothermal engineering. With the rapid development of the construction industry, higher requirements are put forward for the performance of concrete. The corrosion resistance of equipment and materials in the fields of desulfurization equipment, electrochemical tanks, and acid-resistant floors is required to be good, and the current concrete has the problems of low strength and poor corrosion resistance, which limits the practical application of concrete.

[0003] Nano-silicon dioxide is cheap and easy to obtain, has high mechanical strength, and excellent corrosion resistance, and is widely used in building materials such as concrete and asphalt. The surface modification of nano-silicon dioxide has become a research hotspot. Patent CN111423192B discloses that nano-silicon dioxide modified by surface grafting of silane coupling agent and polycaprolactone is used as a modifier, cross-linking of a welan gum solution is used as a cross-linking agent, and surface modification of PVA fibers is carried out, so that modified PVA fibers with hydrophobic surfaces are obtained, and the strength, deformation and other abilities of concrete can be improved. However, the concrete of the patent does not have good acid corrosion resistance. Compared with polyvinyl alcohol (PVA) fibers, nylon fibers have higher strength, higher modulus and better wear resistance, and have better practical application in building materials such as concrete. SUMMARY

[0004] The application solves the problems of poor concrete strength, high water absorption and poor impermeability.

[0005] The technical scheme provided by the application is a preparation method of high-strength corrosion-resistant concrete, which comprises the following components by weight: 55-64 parts of aggregate, 18-22 parts of filler, 12-18 parts of cementing agent, and 0.15-1 part of nano-silicon dioxide modified nylon fiber.

[0006] Further, the cementing material is composed of water glass, sodium fluorosilicate and an additive, the mass fraction of the water glass in the cementing material is 80-86.6%, the mass fraction of the sodium fluorosilicate is 10.8-16.9%, and the mass fraction of the additive is 2.5-4.4%; the additive is polyhydroxymethyl melamine or furfuryl alcohol.

[0007] Further, the preparation method of the high-strength corrosion-resistant concrete is as follows: the aggregate, the filler and the nano-silicon dioxide modified nylon fiber are added into a mixer and stirred and mixed for 1-2 min, then the cementing material is added, stirred and mixed for 2-3 min, poured, vibrated and formed, demolded and maintained, and the high-strength corrosion-resistant concrete is obtained.

[0008] Further, the temperature of curing is 15-30 DEG C, and the curing time is 7-21 days.

[0009] Further, the filler comprises any one or combination of 816 acid-resistant powder, fly ash and basalt fiber.

[0010] Further, the aggregate is composed of coarse aggregate and fine aggregate, the mass fraction of the coarse aggregate in the aggregate is 55-62%, and the mass fraction of the fine aggregate is 38-45%; the coarse aggregate is quartzite with a particle size of 3-10 mm; and the fine aggregate is quartzite with a particle size of ≦3 mm.

[0011] Further, the preparation method of the nano-silica modified nylon fiber is as follows:

[0012] (1) KH570 modified silica, mercaptoethyl pyromellitic diimide are added into N,N-dimethylformamide, after being dispersed, 2,2-dimethoxy-2-phenyl phenylacetone is added, the solution is irradiated under ultraviolet lamp for 20-30 min, then mercaptoethyl pyromellitic diimide and N,N-methylene bisacrylamide are added, wherein the ratio of the KH570 modified silica, the mercaptoethyl pyromellitic diimide and the N,N-methylene bisacrylamide is 1g:(1.5-4.5)g:(0.6-1.8)g, the reaction is continued for 2-4 h, the solvent is filtered, washed with ethanol and dried to obtain poly(amide-imide) grafted silica.

[0013] (2) nylon 6 and poly(amide-imide) grafted silica with a ratio of 1g:(0.05-0.3)g are mixed in a high-speed mixer, then melt spinning is carried out through a single screw spinning machine, the temperature of the 1-4 zones of the melt spinning machine is 250-265 DEG C, the screw rotation speed is 20-30 r / min, and the spinning speed is 300-800 m / min; after spinning, stretching is carried out, the stretching multiple is 3-4 times; and winding and collection are carried out to obtain the nano-silica modified nylon fiber.

[0014] Further, the preparation method of the mercaptoethyl pyromellitic diimide is as follows: pyridine, mercaptoethylamine and pyromellitic anhydride are added into toluene, heated and stirred to reflux, the solvent is removed by rotary evaporation, the product is recrystallized in ethyl acetate to obtain the mercaptoethyl pyromellitic diimide.

[0015] The technical effect of the present application is that the alkenyl group of the KH570 modified silica is used as a polymerization site, the mercaptoethyl pyromellitic diimide and the N,N-methylene bisacrylamide are subjected to in-situ polymerization reaction on the surface of the silica through mercapto-alkene click reaction, the poly(amide-imide) polymer molecular chain is grafted on the surface of the nano-silica, and the poly(amide-imide) polymer grafted silica is obtained.

[0016] The application blends and spins poly(amide-imide) grafted silica and nylon 6, the surface of the silica is grafted with a polymer containing polyamide structure, the polymer has good compatibility with the polyamide molecular chain of nylon 6, thereby improving the interfacial compatibility of nano-silica and nylon 6, making nano-silica can be uniformly dispersed in nylon 6 fiber, significantly improving the breaking performance of the fiber, and the polymer contains rigid imide structure units, which is beneficial to improve the strength of the nylon fiber, the breaking strength of the fiber reaches 4.14-5.13 cN·dtex -1 , and the elongation at break reaches 105.0-149.8%.

[0017] The application uses quartz stone aggregate, 816 acid-resistant powder, fly ash, basalt fiber and other concrete matrix as the base, water glass, sodium fluorosilicate, polyhydroxymethyl melamine or furfuryl alcohol as the cementing agent, and adds poly(amide-imide) grafted silica with excellent mechanical properties, the silica nylon composite fiber forms a reinforcing phase in the concrete, plays a role in filling the gap of the concrete and supporting the framework, and significantly improves the compressive strength of the concrete. After being soaked in sulfuric acid, the concrete still maintains high compressive strength and strength retention rate. This is because the cementing material composed of water glass, sodium fluorosilicate, furfuryl alcohol or polyhydroxymethyl melamine forms a chemically stable silicon-based solidification crosslinking network during the solidification of the concrete, and has good acid corrosion resistance. The added nylon fiber contains poly(amide-imide) grafted silica, which itself has strong acid corrosion resistance and is difficult to react with sulfuric acid. The surface grafted poly(amide-imide) polymer contains corrosion-resistant imide structure, has strong acid resistance and excellent corrosion resistance. After being soaked in sulfuric acid, the nylon fiber will not be corroded by sulfuric acid, and still maintains good structural stability and mechanical strength, thereby not affecting the mechanical strength of the concrete. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the preparation reaction formula of mercaptoethyl dianilino-1, 4-benzenetetracarboxylic acid imide.

[0019] Figure 2 is the reaction principle of poly(amide-imide) grafted silica. DETAILED DESCRIPTION

[0020] The coarse aggregate of the application is quartz stone with a particle size of 3-10 mm, and the fine aggregate is quartz stone with a particle size of ≤3 mm. The water glass mainly contains sodium silicate, has a Baume degree of 40 and a modulus of 2.6. The 816 acid-resistant powder is a power plant 1st grade fly ash. The basalt fiber has a product model of AF53 and a thickness of 25 mm. The nylon 6 has a brand of JQC-2750. The nano-silica has an average particle size of 20 nm. The 816 acid-resistant powder is obtained by calcining, grinding and fine grinding of a flow banded porphyry primary ore. The main component is quartz.

[0021] Example 1

[0022] (1) 24 mmol of pyridine, 8 mmol of mercaptoethylamine, and 4 mmol of pyromellitic anhydride were added to 10 mL of toluene, heated to 110°C, and stirred to reflux for 8 h. The solvent was removed by rotary evaporation, and the product was recrystallized in ethyl acetate to obtain mercaptoethyl pyromellitic diimide.

[0023] (2) 1 g of nano-silica was added to 10 mL of distilled water and 70 mL of ethanol, dispersed, and then 20 mL of an ethanol solution containing 0.6 g of KH550 was added. The mixture was reacted at 75°C for 5 h, centrifuged, and washed with ethanol to obtain KH570-modified silica.

[0024] (3) 1 g of KH570-modified silica and 0.2 g of mercaptoethyl pyromellitic diimide were added to 30 mL of N,N-dimethylformamide, dispersed, and then 22 mg of 2,2-dimethoxy-2-phenylacetophenone was added. The solution was irradiated under a 60W ultraviolet lamp for 20 min, and then 1.3 g of mercaptoethyl pyromellitic diimide and 0.6 g of N,N-methylenebisacrylamide were added. The reaction was continued for 2 h, the solvent was filtered, washed with ethanol, and dried to obtain poly(amide-imide) grafted silica.

[0025] (4) 200 g of nylon 6 and 10 g of poly(amide-imide) grafted silica were mixed in a high-speed mixer, and then melt spun through a single-screw spinning machine. The temperature of the melt spinning machine was 250°C, 265°C, 265°C, and 260°C in zones 1-4, the screw rotation speed was 20 r / min, and the spinning speed was 600 m / min. After spinning, the fibers were stretched at a draw ratio of 3, wound and collected to obtain nano-silica modified nylon fibers.

[0026] (5) 55 kg of aggregate (composed of 33.6 kg of coarse aggregate and 21.4 kg of fine aggregate), 22 kg of filler (composed of 15 kg of 816 acid-resistant powder and 7 kg of fly ash), and 0.15 kg of nano-silica modified nylon fibers were added to a mixer and stirred for 1 min. Then, 12 kg of cementitious material (composed of 10.4 kg of water glass, 1.3 kg of sodium fluorosilicate, and 0.3 kg of furfuryl alcohol additive) was added and stirred for 2 min. The mixture was poured and vibrated to form a mold, demolded, and cured at 25°C for 14 days to obtain high-strength corrosion-resistant concrete.

[0027] Example 2

[0028] (1), 1 g of KH570 modified silica (same preparation method as in Example 1), 0.2 g of mercaptoethyl durene diimine (same preparation method as in Example 1) were added to 50 mL of N,N-dimethylformamide, after dispersion, 35 mg of 2,2-dimethoxy-2-phenylacetophenone was added, the solution was irradiated under a 60W ultraviolet lamp for 20 min, then 2.6 g of mercaptoethyl durene diimine, 1 g of N,N-methylene bisacrylamide was added, and the reaction was continued for 3 h, the solvent was filtered, washed with ethanol, and dried to obtain poly(amide-imide) grafted silica.

[0029] (2), 200 g of nylon 6, 30 g of poly(amide-imide) grafted silica were mixed in a high-speed mixer, then melt spinning was carried out by a single screw spinning machine, the temperature of the melt spinning machine 1-4 zone was 250℃, 265℃, 265℃, 260℃, the screw rotation speed was 20 r / min, and the spinning speed was 800 m / min; after spinning, stretching was carried out, the stretching ratio was 4 times; winding collection was carried out to obtain nano-silica modified nylon fiber.

[0030] (3), 58 kg of aggregate (consisting of 31.9 kg of coarse aggregate, 26.1 kg of fine aggregate), 18 kg of filler (consisting of 15 kg of 816 acid-resistant powder, 3 kg of basalt fiber), 0.4 kg of nano-silica modified nylon fiber were added to a mixer and stirred and mixed for 2 min, then 14 kg of cementing material (consisting of 11.3 kg of water glass, 2.1 kg of sodium fluorosilicate, 0.6 kg of additive polyoxymethylene melamine) was added, stirred and mixed for 2 min, poured, vibrated and formed, demolded, cured at 25℃ for 14 days to obtain high-strength corrosion-resistant concrete.

[0031] Example 3

[0032] (1), 1 g of KH570 modified silica (same preparation method as in Example 1), 0.2 g of mercaptoethyl durene diimine (same preparation method as in Example 1) were added to 50 mL of N,N-dimethylformamide, after dispersion, 35 mg of 2,2-dimethoxy-2-phenylacetophenone was added, the solution was irradiated under a 60W ultraviolet lamp for 20 min, then 2.6 g of mercaptoethyl durene diimine, 1 g of N,N-methylene bisacrylamide was added, and the reaction was continued for 3 h, the solvent was filtered, washed with ethanol, and dried to obtain poly(amide-imide) grafted silica.

[0033] (2), 200 g of nylon 6 and 45 g of poly(amide-imide) grafted silica were mixed in a high-speed mixer, and then melt spinning was performed by a single screw spinning machine, the temperature of the 1-4 zones of the melt spinning machine was 250°C, 265°C, 265°C, and 260°C, the screw rotation speed was 20 r / min, and the spinning speed was 800 m / min; after spinning, stretching was performed, the stretching multiple was 3.5 times; winding and collection were performed, and a nano-silica modified nylon fiber was obtained.

[0034] (3), 60 kg of aggregate (consisting of 37.2 kg of coarse aggregate and 22.8 kg of fine aggregate), 20 kg of filler (consisting of 16 kg of 816 acid-resistant powder and 4 kg of basalt fiber), and 0.7 kg of nano-silica modified nylon fiber were added to a mixer and stirred and mixed for 1 min, then 16 kg of cementing material (consisting of 12.9 kg of water glass, 2.7 kg of sodium fluorosilicate, and 0.4 kg of furfuryl alcohol as an additive) was added, and stirring and mixing were performed for 3 min, and then pouring, vibration molding, demolding, and 25°C curing for 14 days were performed, and a high-strength corrosion-resistant concrete was obtained.

[0035] Example 4

[0036] (1), 1 g of KH570 modified silica (prepared in the same manner as in Example 1) and 0.2 g of mercaptoethyl isophthalic acid diimide (prepared in the same manner as in Example 1) were added to 60 mL of N,N-dimethylformamide, and after dispersion, 65 mg of 2,2-dimethoxy-2-phenylphenylacetone was added, and the solution was irradiated under a 60W ultraviolet lamp for 30 min, then 4.3 g of mercaptoethyl isophthalic acid diimide and 1.8 g of N,N-methylenebisacrylamide were added, and the reaction was continued for 4 h, the solvent was filtered, washed with ethanol, and dried, and poly(amide-imide) grafted silica was obtained.

[0037] (2), 200 g of nylon 6 and 45 g of poly(amide-imide) grafted silica were mixed in a high-speed mixer, and then melt spinning was performed by a single screw spinning machine, the temperature of the 1-4 zones of the melt spinning machine was 250°C, 265°C, 265°C, and 260°C, the screw rotation speed was 20 r / min, and the spinning speed was 800 m / min; after spinning, stretching was performed, the stretching multiple was 3.5 times; winding and collection were performed, and a nano-silica modified nylon fiber was obtained.

[0038] (3), 64 kg of aggregate (consisting of 38.4 kg of coarse aggregate, 25.6 kg of fine aggregate), 20 kg of filler (consisting of 15 kg of 816 acid-resistant powder, 6 kg of fly ash), 1 kg of nano-silicon dioxide modified nylon fiber are added to the blender and stirred and mixed for 2 min, then 18 kg of cementing material (14.4 kg of water glass, 2.8 kg of sodium fluorosilicate, 0.8 kg of additive polyoxymethylene melamine) is added, stirred and mixed for 2 min, poured, vibrated and formed, demolded, and cured at 25°C for 14 days to obtain high-strength corrosion-resistant concrete.

[0039] Comparative Example 1

[0040] (1), 55 kg of aggregate (consisting of 33.6 kg of coarse aggregate, 21.4 kg of fine aggregate), 22 kg of filler (consisting of 15 kg of 816 acid-resistant powder, 7 kg of fly ash) are added to the blender and stirred and mixed for 1 min, then 12 kg of cementing material (10.4 kg of water glass, 1.3 kg of sodium fluorosilicate, 0.3 kg of additive furfuryl alcohol) is added, stirred and mixed for 2 min, poured, vibrated and formed, demolded, and cured at 25°C for 14 days to obtain high-strength corrosion-resistant concrete.

[0041] Comparative Example 2

[0042] (1), 200 g of nylon 6 is melt-spun in a single-screw spinning machine, the temperature of the melt spinning machine 1-4 zones is 250°C, 265°C, 265°C, 260°C, the screw rotation speed is 20 r / min, and the spinning speed is 600 m / min; after spinning, stretching is performed with a stretching ratio of 3 times; and winding and collection are performed to obtain nylon fiber.

[0043] (2), 55 kg of aggregate (consisting of 33.6 kg of coarse aggregate, 21.4 kg of fine aggregate), 22 kg of filler (consisting of 15 kg of 816 acid-resistant powder, 7 kg of fly ash), 0.15 kg of nylon fiber are added to the blender and stirred and mixed for 1 min, then 12 kg of cementing material (10.4 kg of water glass, 1.3 kg of sodium fluorosilicate, 0.3 kg of additive furfuryl alcohol) is added, stirred and mixed for 2 min, poured, vibrated and formed, demolded, and cured at 25°C for 14 days to obtain high-strength corrosion-resistant concrete.

[0044] Comparative Example 3

[0045] (1), 1.5 g of mercaptoethyl dianilino phthalic acid diimide (prepared in the same manner as in Example 1), 22 mg of 2,2-dimethoxy-2-phenylacetophenone, and 0.6 g of N,N-methylene bisacrylamide are added to 30 mL of N,N-dimethylformamide, reacted for 2 h, distilled under reduced pressure, washed with ethanol, and dried to obtain poly(amide-imide).

[0046] (2), 200 g of nylon 6, 10 g of poly(amide-imide) were mixed in a high-speed mixer, and then melt spinning was performed by a single screw spinning machine, the temperature of the 1-4 zones of the melt spinning machine was 250℃, 265℃, 265℃, 260℃, the screw rotation speed was 20 r / min, and the spinning speed was 600 m / min; after spinning, stretching was performed, the stretching multiple was 3 times; winding and collection were performed, and modified nylon fibers were obtained.

[0047] (3), 55 kg of aggregate (composed of 33.6 kg of coarse aggregate and 21.4 kg of fine aggregate), 22 kg of filler (composed of 15 kg of 816 acid-resistant powder and 7 kg of fly ash), and 0.15 kg of modified nylon fibers were added to a mixer and stirred and mixed for 1 min, then 12 kg of cementing material (composed of 10.4 kg of water glass, 1.3 kg of sodium fluorosilicate, and 0.3 kg of furfuryl alcohol as an additive) was added, stirred and mixed for 2 min, poured, vibrated and formed, demolded, and cured at 25℃ for 14 days to obtain high-strength corrosion-resistant concrete.

[0048] Comparative Example 4

[0049] (1), 200 g of nylon 6 and 10 g of nano-silicon dioxide were mixed in a high-speed mixer, and then melt spinning was performed by a single screw spinning machine, the temperature of the 1-4 zones of the melt spinning machine was 250℃, 265℃, 265℃, 260℃, the screw rotation speed was 20 r / min, and the spinning speed was 600 m / min; after spinning, stretching was performed, the stretching multiple was 3 times; winding and collection were performed, and nano-silicon dioxide modified nylon fibers were obtained.

[0050] (2), 55 kg of aggregate (composed of 33.6 kg of coarse aggregate and 21.4 kg of fine aggregate), 22 kg of filler (composed of 15 kg of 816 acid-resistant powder and 7 kg of fly ash), and 0.15 kg of nano-silicon dioxide modified nylon fibers were added to a mixer and stirred and mixed for 1 min, then 12 kg of cementing material (composed of 10.4 kg of water glass, 1.3 kg of sodium fluorosilicate, and 0.3 kg of furfuryl alcohol as an additive) was added, stirred and mixed for 2 min, poured, vibrated and formed, demolded, and cured at 25℃ for 14 days to obtain high-strength corrosion-resistant concrete.

[0051] Comparative Example 5

[0052] (1), 200 g of nylon 6 and 10 g of KH570 modified silicon dioxide were mixed in a high-speed mixer, and then melt spinning was performed by a single screw spinning machine, the temperature of the 1-4 zones of the melt spinning machine was 250℃, 265℃, 265℃, 260℃, the screw rotation speed was 20 r / min, and the spinning speed was 600 m / min; after spinning, stretching was performed, the stretching multiple was 3 times; winding and collection were performed, and nano-silicon dioxide modified nylon fibers were obtained.

[0053] (2), 55 kg of aggregate (consisting of 33.6 kg of coarse aggregate and 21.4 kg of fine aggregate), 22 kg of filler (consisting of 15 kg of 816 acid-resistant powder and 7 kg of fly ash), and 0.15 kg of nano-silica modified nylon fiber were added to a mixer and stirred and mixed for 1 min, then 12 kg of cementing material (consisting of 10.4 kg of water glass, 1.3 kg of sodium fluorosilicate, and 0.3 kg of glycol) was added, stirred and mixed for 2 min, poured, vibrated and formed, demolded, and cured at 25°C for 14 days to obtain high-strength corrosion-resistant concrete.

[0054] The breaking strength of the nylon fiber was tested by a fiber strength tester, the clamping distance was 200 mm, and the stretching speed was 200 mm / min. Ten samples were taken from each group of fibers, and the test results were averaged.

[0055] Table 1: Performance test of nylon fiber

[0056] Breaking strength (cN·dtex -1 )]]> Elongation at break (%) Example 1 4.14 135.7 Example 2 5.13 105.0 Example 3 4.41 149.8 Example 4 4.60 119.6 Comparative Example 2 2.55 49.6 Comparative Example 3 2.91 57.7 Comparative Example 4 3.02 72.5 Comparative Example 5 3.36 83.4

[0057] In Examples 1-4, poly(amide-imide) grafted silica was blended and spun with nylon 6, the surface of the silica was grafted with a polymer containing a polyamide structure, which had good compatibility with the polyamide molecular chain of nylon 6, thereby improving the interfacial compatibility of nano-silica and nylon 6, allowing the nano-silica to be uniformly dispersed in the nylon 6 fiber, significantly improving the breaking performance of the fiber, and the polymer contained a rigid imide structure unit, which was beneficial to improving the strength of the nylon fiber. The breaking strength of the fiber reached 4.14-5.13 cN·dtex -1 , and the breaking elongation reached 105.0-149.8%.

[0058] In Comparative Example 2, poly(amide-imide) grafted silica was not added to nylon 6, and the breaking strength of the obtained nylon fiber was only 2.55 cN·dtex -1 , and the breaking elongation was only 49.6%.

[0059] In Comparative Example 3, only poly(amide-imide) polymer was added to the nylon fiber compared with Examples 1 and Comparative Example 2, the polymer contained a polyamide structure and a rigid imide structure unit, had good compatibility with nylon 6, and could improve the breaking performance of the nylon fiber, the breaking strength and breaking elongation were greater than those of Comparative Example 2, but without the addition of nano-silica, the breaking strength and breaking elongation were lower than those of Example 1.

[0060] In Comparative Example 3, nylon 6 was blended and spun with unmodified nano-silica, the nano-silica was not surface modified, had poor compatibility with nylon 6, and had low dispersibility in the nylon fiber, which had a low improvement rate for the breaking performance of the fiber.

[0061] Comparative Example 4 blends and spins nylon 6 and KH570 modified nano-silica. The compatibility of the nano-silica with nylon 6 is improved to some extent after the surface modification of the nano-silica with KH570. However, KH570 does not contain amide structural units, and its compatibility is weaker than that of the poly(amide-imide) polymer, resulting in a lower dispersibility of the KH570 modified nano-silica in the nylon fiber of Comparative Example 4 than the poly(amide-imide) grafted silica of Example 1. Therefore, the breaking performance of the nylon fiber of Comparative Example 4 is lower than that of Example 1.

[0062] The compressive strength of the concrete was tested according to the method of GB 50212-2014 “Code for Construction of Anti-corrosion Engineering”. Five samples were taken from each group of concrete, and the test results were averaged. The concrete was placed in a 10-40% hydrochloric acid or sulfuric acid solution and soaked for 30 days. After removal, it was washed with water and dried before testing the compressive strength.

[0063] Table 2. Compressive strength and corrosion resistance of concrete

[0064]

[0065]

[0066] The poly(amide-imide) grafted silica with better mechanical properties was added to the concrete of Examples 1-4. The silica-nylon composite fiber formed a reinforcing phase in the concrete, filling the gaps in the concrete and supporting the framework, significantly improving the compressive strength of the concrete. After sulfuric acid immersion, the concrete still maintained a very high compressive strength and strength retention rate. This is mainly because the cementing material composed of water glass, sodium fluorosilicate, furfuryl alcohol or polyhydroxymethyl melamine forms a chemically stable silica-based solidification crosslinking network during the solidification of the concrete, which has good acid corrosion resistance. Secondly, the poly(amide-imide) grafted silica is added to the nylon fiber. The nano-silica itself has strong acid corrosion resistance and is difficult to react with sulfuric acid. The surface grafted poly(amide-imide) polymer contains corrosion-resistant imide structures, has strong acid resistance, and excellent corrosion resistance. After sulfuric acid immersion, the nylon fiber will not be corroded by sulfuric acid, and will still maintain good structural stability and mechanical strength, thereby not affecting the mechanical strength of the concrete.

Claims

1. A method for preparing high-strength, corrosion-resistant concrete, characterized in that, The concrete comprises the following components in parts by weight: 55-64 parts aggregate, 18-22 parts filler, 12-18 parts binder, and 0.15-1 parts nano-silica modified nylon fiber. The binder is composed of water glass, sodium fluorosilicate, and additives. The mass fraction of water glass in the binder is 80-86.6%; the mass fraction of sodium fluorosilicate is 10.8-16.9%; and the mass fraction of additives is 2.5-4.4%. The additives are polymethyl melamine or furfuryl alcohol. The preparation method of the high-strength corrosion-resistant concrete is as follows: aggregate, filler, and nano-silica modified nylon fiber are added to a mixer and mixed, then binder is added, mixed evenly, poured, vibrated and shaped, demolded and cured to obtain high-strength corrosion-resistant concrete. The filler includes any one or a combination of 816 acid-resistant powder, fly ash, and basalt fiber; the 816 acid-resistant powder is made from rhyolite porphyry ore by high-temperature calcination and grinding, and its main component is quartz. The preparation method of the nano-silica modified nylon fiber is as follows: (1) Add KH570 modified silica and mercaptoethylpyromellitic acid diimide to N,N-dimethylformamide, disperse, add 2,2-dimethoxy-2-phenylacetophenone, irradiate the solution under ultraviolet light for 20-30 min, then add mercaptoethylpyromellitic acid diimide and N,N-methylenebisacrylamide, continue the reaction for 2-4 h, filter the solvent, wash, dry, and obtain poly(amide-imide) grafted silica; (2) Nylon 6 and poly(amide-imide) grafted silica are mixed in a high-speed mixer, and then melt-spun, stretched, wound and collected by a single screw spinning machine to obtain nano silica modified nylon fiber. The ratio of KH570 modified silica, mercaptoethylpyromellitic diimide, and N,N-methylenebisacrylamide in (1) is 1g:(1.5-4.5)g:(0.6-1.8)g; In (2), the ratio of nylon 6 to poly(amide-imide) grafted silica is 1g:(0.05-0.3)g; The preparation method of the mercaptoethylpyromellitic diimide is as follows: pyridine, mercaptoethylamine, and pyromellitic anhydride are added to toluene, the mixture is heated and stirred under reflux, the solvent is removed by rotary evaporation, and the mixture is recrystallized to obtain mercaptoethylpyromellitic diimide, with the structural formula [insert structural formula here]. .

2. The method for preparing high-strength corrosion-resistant concrete according to claim 1, characterized in that, The stirring and mixing time is 1-2 minutes; the mixing time is 2-3 minutes.

3. The method for preparing high-strength corrosion-resistant concrete according to claim 1, characterized in that, The curing temperature is 15-30℃, and the curing time is 7-21 days.

4. The method for preparing high-strength corrosion-resistant concrete according to claim 1, characterized in that, The aggregate consists of coarse aggregate and fine aggregate, with the mass fraction of coarse aggregate being 55-62% and the mass fraction of fine aggregate being 38-45%. The coarse aggregate is quartz with a particle size of 3-10 mm, and the fine aggregate is quartz with a particle size of ≤3 mm.

5. The method for preparing high-strength corrosion-resistant concrete according to claim 1, characterized in that, In (2), the temperature of zones 1-4 of the melt spinning machine is 250-265℃, the screw speed is 20-30r / min, the spinning speed is 300-800m / min, and the stretching ratio is 3-4 times.

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