A kind of anti-seepage and waterproof fiber reinforced concrete and preparation method thereof

Abstract

The invention relates to the technical field of concrete materials and discloses an anti-seepage and waterproof fiber-reinforced concrete and a preparation method thereof. After organic fluorine is introduced into polyester fibers, the carbon chains are surrounded by a series of stable fluorine atoms, exhibiting excellent alkali resistance. At the same time, fluorocarbon chains with lower surface free energy are more easily enriched on the surface, thereby improving the microstructure of the concrete. The modified polyester fibers form a cross-net support system in the concrete matrix, reducing water precipitation on the concrete surface, blocking capillary channels in the concrete, making water migration difficult, and significantly improving the anti-seepage and waterproof properties. Strong bonding and mechanical engagement exist between the interface of the modified polyester fibers and the cement concrete-based material, weakening the shrinkage stress of the concrete, effectively preventing the peeling of the concrete surface material during the freezing and thawing process, and thereby improving the anti-freeze performance of the concrete.

Description

[0001] This application is a divisional application with the application date of March 15, 2024, application number 202410296405.8, and the invention name is "A kind of anti-seepage and waterproof fiber reinforced concrete and its preparation method." Technical Field

[0002] The present invention relates to the technical field of concrete materials, in particular to anti-seepage and waterproof fiber reinforced concrete and a preparation method thereof. Background Art

[0003] With the rapid development of modern economic construction and national defense construction, higher requirements are placed on engineering quality and durability. Concrete, as a building material with a long history, has played an important role in all fields of construction engineering. However, concrete is a brittle material. Its biggest disadvantage is that it is easy to crack under various effects due to its brittleness. This has limited the wider application of concrete in engineering to a certain extent. As building components develop towards large volume, large area, and complex and diverse shapes, the stress in the concrete is large and complex, and cracks appear much more frequently than before. Therefore, in order to reduce the structural damage of cement concrete caused by cracks, in addition to paying attention to the impermeability of concrete, more attention should be paid to leakage caused by insufficient waterproofness of concrete. Among them, fiber-reinforced concrete has attracted widespread attention.

[0004] In the existing technology, the fibers used in fiber concrete mainly include steel fibers, natural fibers and artificial fibers. Among them, although steel fibers have stable mechanical properties, they are difficult to promote and apply in many fields due to their disadvantages such as high specific gravity, difficulty in dispersion, easy corrosion and high cost. With the advancement of the chemical industry, artificial fibers have developed rapidly, and a variety of fibers with excellent performance have replaced original fibers and are used in concrete. Among them, polypropylene fibers have high fiber strength, good corrosion resistance, low cost and good dispersibility, becoming the most widely used fiber for reinforcing concrete in the construction industry. However, polypropylene fibers have problems such as easy photooxidative aging, thermal oxidative aging, high temperature failure, and low temperature brittleness. Ordinary polypropylene materials age and disintegrate rapidly under the action of ultraviolet rays and cannot be widely used, and cannot achieve the expected effect of crack resistance and reinforcement.

[0005] In addition to the excellent properties of polypropylene fibers, polyester fibers also have good light resistance and oxidation resistance. They are cheaper than polypropylene fibers and have the advantages of polypropylene fibers while making up for their shortcomings. If they can be applied to concrete, they will produce better benefits. However, existing polyester fibers have insufficient alkali resistance and cannot withstand the strong alkalinity in concrete materials. Therefore, the present invention modifies polyester monomers, introduces fluorine-containing functional groups with good alkali resistance and water resistance into monomers with similar structures to polyester, and then polymerizes and melt-spins them. The resulting modified polyester fibers have the characteristics of high strength, easy dispersion, and large fineness. They also have high temperature resistance, can be evenly dispersed in concrete, have good bonding strength with the cement matrix, and have good anti-seepage and water resistance in alkaline concrete media. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide an anti-seepage and waterproof fiber reinforced concrete and a preparation method thereof, thereby solving the problem of poor anti-seepage and waterproof performance of the existing concrete.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] The invention discloses an anti-seepage and waterproof fiber-reinforced concrete, comprising the following components in parts by weight: 300-350 parts of cement, 150-180 parts of water, 1050-1180 parts of aggregate, 100-140 parts of slag powder, 650-800 parts of yellow sand, 10-80 parts of fly ash and 2-5 parts of polycarboxylate water-reducing agent, and also comprising modified polyester fiber accounting for 0.3-1.5% of the total weight of the above components.

[0009] The preparation method is as follows: add modified polyester fiber, polycarboxylate water reducer and water into a mixer, stir at a temperature of 45-60°C for 10-20 minutes, then add cement, slag powder and yellow sand at 30-40°C, stir for 20-30 minutes, and finally add aggregate and fly ash, stir at 20-35°C for 25-40 minutes to obtain anti-seepage and waterproof fiber reinforced concrete.

[0010] The aggregate is crushed gravel with a particle size of 10-25 mm.

[0011] Furthermore, the preparation method of the modified polyester fiber is as follows: (1) under a nitrogen atmosphere, 2,2'-[1,4-phenylenebis(oxymethylene)]dioxirane and xylene are added to a reaction flask equipped with a reflux condenser, and after stirring evenly, 2H,2H,3H,3H-heptadecafluoroundecanoic acid and triethylamine are added, and the reaction is stirred. After the reaction is completed, reduced pressure distillation is performed to obtain 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl ester)diol.

[0012] (2) Under nitrogen atmosphere, terephthalic acid, ethylene glycol and 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl)diol are added to the reactor, mixed evenly, and then esterification reaction is carried out. Then, antimony trioxide catalyst and triphenyl phosphite heat stabilizer are added, and vacuum is applied to reduce the pressure in the reactor to 10-20 Pa for polycondensation reaction. After the reaction is completed, nitrogen is squeezed out, cooled and solidified in a water tank, and pelletized to obtain fluorinated polyester chips.

[0013] (3) The fluorinated polyester chips were placed in a drying oven at 100-120°C for 5-12 hours, placed in a single-screw melt spinning machine for melt spinning at a spinning temperature of 245-270°C and a spinning speed of 230-250 r / min, and then placed in a fiber stretching instrument for heat stretching to obtain modified polyester fibers.

[0014] Furthermore, in step (1), the ratio of 2,2'-[1,4-phenylenebis(oxymethylene)]dioxirane, 2H,2H,3H,3H-heptadecafluoroundecanoic acid, and triethylamine is 1 mol:(2.05-2.2) mol:(2.1-2.4) mol.

[0015] Furthermore, in step (1), the reaction temperature is 110-130° C., and the reaction time is 3-8 h.

[0016] Furthermore, in step (2), the ratio of terephthalic acid, ethylene glycol, 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl)diol, catalyst antimony trioxide, and thermal stabilizer triphenyl phosphite is (2.05-2.15) mol:1 mol:(0.95-1.1) mol:(0.1-0.2) mol:(0.05-0.08) mol.

[0017] Furthermore, in step (2), the esterification reaction temperature is 210-230° C., and the esterification reaction time is 5-12 h.

[0018] Furthermore, in step (2), the polycondensation reaction temperature is 250-280° C., and the polycondensation reaction time is 2-5 h.

[0019] Furthermore, in step (3), the temperatures of screw zones 1 to 4 of the single-screw melt spinning machine are set to 245-255°C, 250-260°C, 255-265°C, and 260-270°C, respectively, and the head temperature is 270-280°C.

[0020] Furthermore, in step (3), the heat stretching temperature is 115-130° C., and the heat stretching time is 5-10 min.

[0021] By adopting the above technical solution, the beneficial effects of the present invention are:

[0022] The present invention firstly utilizes the epoxy group of 2,2'-[1,4-phenylenebis(oxymethylene)]dioxirane to react with the carboxylic acid of 2H,2H,3H,3H-heptadecafluoroundecanoic acid to obtain 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl ester)diol, then carries out esterification and polycondensation reaction with phthalic acid and ethylene glycol, obtains fluorinated polyester chips after water-cooling pelletization, and then obtains modified polyester fibers after melt spinning and heat stretching. Finally, the fibers are mixed with cement, slag powder, yellow sand, etc. to obtain anti-seepage and waterproof fiber-reinforced concrete.

[0023] 2,2'-[1,4-phenylenebis(oxymethylene)]dioxirane has both a benzene ring and a fatty segment, and is similar to the molecular structure of polyester. The modified polyester fiber obtained after the introduction of fluorine-containing groups has high tensile strength, mechanical properties and alkali resistance. The strength does not decrease basically after soaking in sodium hydroxide solution. After the introduction of organic fluorine into the polyester fiber, the carbon chain is surrounded by a series of stable fluorine atoms. The shielding effect of fluorine's electron cloud on the main chain is stronger than that of hydrogen atoms, making it difficult for any reaction reagent to insert, showing excellent chemical resistance; at the same time, the fluorine-carbon chain with lower surface free energy is more likely to be enriched on the surface, thereby improving the hydrophobic and oleophobic properties and acid and alkali resistance of polyester. The modified polyester fiber solves the problem of poor alkali resistance of traditional polyester fiber and is successfully used in silicate cement concrete, improving the microstructure of concrete and improving mechanical properties and durability.

[0024] The modified polyester fiber contains fluorine-containing groups with excellent hydrophobicity, which can be enriched on the fiber surface and have a certain waterproof effect. The modified polyester fiber forms a cross-network support system in the concrete matrix, which plays the role of supporting aggregates, preventing the settlement of materials to a certain extent, reducing the water precipitation phenomenon on the concrete surface, and effectively preventing the volume shrinkage in the plastic period caused by water loss on the concrete surface, inhibiting the appearance of plastic cracks, limiting the generation of new cracks, and having a strong binding effect on existing cracks, thereby ensuring the continuity and integrity of the concrete matrix. In addition, the addition of modified polyester fibers can block the capillary channels in the concrete, making the migration of water difficult, and having a more significant effect on the refinement of cracks, and significantly improving the anti-seepage and waterproofing properties.

[0025] There is a strong bonding force and mechanical meshing force between the modified polyester fiber and the cement concrete-based material interface, which weakens the shrinkage stress of the concrete, greatly reduces the shrinkage cracks of the concrete, and plays a role in blocking the development of microcracks in the block, thereby effectively preventing the peeling of the concrete surface material during the freeze-thaw process. At the same time, during the freeze-thaw cycle, the modified polyester fiber relieves part of the internal temperature stress caused by temperature changes, thereby preventing the development of temperature cracks, thereby improving the frost resistance of the concrete. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention.

[0027] 2,2'-[1,4-phenylenebis(oxymethylene)]dioxirane, CAS number 2425-01-6.

[0028] 2H,2H,3H,3H-heptadecafluoroundecanoic acid, CAS number 34598-33-9.

[0029] Undecanoic acid, CAS number 112-37-8.

[0030] Example 1

[0031] (1) Under nitrogen atmosphere, 25 mmol of 2,2'-[1,4-phenylenebis(oxymethylene)]dioxirane and 175 mL of xylene were added to a reaction flask equipped with a reflux condenser. After stirring evenly, 52.5 mmol of 2H,2H,3H,3H-heptadecafluoroundecanoic acid and 55 mmol of triethylamine were added. The mixture was reacted at 120°C for 5 h and distilled under reduced pressure to obtain 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl)diol. The preparation reaction formula is:

[0032]

[0033] (2) Under nitrogen atmosphere, 21 mmol of terephthalic acid, 10 mmol of ethylene glycol and 10.5 mmol of 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl)diol were added to the reactor, mixed evenly, and then esterification reaction was carried out at 220 ° C for 10 hours. Then, 1.5 mmol of antimony trioxide as a catalyst and 0.6 mmol of triphenyl phosphite as a heat stabilizer were added. The pressure in the reactor was reduced to 15 Pa by vacuum pumping, and polycondensation reaction was carried out at 260 ° C for 3 hours. The product was squeezed out with nitrogen, cooled and solidified in a water tank and pelletized to obtain fluorinated polyester chips.

[0034] (3) The fluorinated polyester chips were placed in a drying oven at 110°C for 9 hours and then placed in a single-screw melt spinning machine for melt spinning. The spinning temperature was 260°C and the spinning speed was 240 r / min. The temperatures of the screw zones 1 to 4 of the single-screw melt spinning machine were set to 250°C, 255°C, 260°C, and 270°C, respectively, and the head temperature was 275°C. The chips were then placed in a fiber stretching instrument for hot stretching at a temperature of 125°C and a time of 8 minutes to obtain modified polyester fibers.

[0035] Example 2

[0036] (1) Under nitrogen atmosphere, 35 mmol of 2,2'-[1,4-phenylenebis(oxymethylene)]dioxirane and 175 mL of xylene were added to a reaction flask equipped with a reflux condenser. After stirring evenly, 71.8 mmol of 2H,2H,3H,3H-heptadecafluoroundecanoic acid and 73.5 mmol of triethylamine were added. The mixture was reacted at 130°C for 3 h and distilled under reduced pressure to obtain 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl)diol.

[0037] (2) Under nitrogen atmosphere, 10.25 mmol of terephthalic acid, 5 mmol of ethylene glycol and 4.75 mmol of 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl)diol were added to the reactor, mixed evenly, and then esterification reaction was carried out at 230 ° C for 5 h. Then, 0.5 mmol of catalyst antimony trioxide and 0.25 mmol of heat stabilizer triphenyl phosphite were added. The pressure in the reactor was reduced to 20 Pa by vacuum, and polycondensation reaction was carried out at 280 ° C for 2 h. The product was squeezed out with nitrogen, cooled and solidified in a water tank and pelletized to obtain fluorinated polyester chips.

[0038] (3) The fluorinated polyester chips were placed in a drying oven at 120°C for 5 h, and then placed in a single-screw melt spinning machine for melt spinning. The spinning temperature was 270°C, the spinning speed was 250 r / min, the temperatures of the screw zones 1 to 4 of the single-screw melt spinning machine were set to 255°C, 260°C, 255°C, and 265°C, respectively, and the head temperature was 280°C. The chips were then placed in a fiber stretching instrument for hot stretching at a temperature of 130°C and a time of 5 min to obtain modified polyester fibers.

[0039] Example 3

[0040] (1) Under nitrogen atmosphere, 10 mmol of 2,2'-[1,4-phenylenebis(oxymethylene)]dioxirane and 80 mL of xylene were added to a reaction flask equipped with a reflux condenser. After stirring evenly, 22 mmol of 2H,2H,3H,3H-heptadecafluoroundecanoic acid and 24 mmol of triethylamine were added. The mixture was reacted at 110°C for 8 h and distilled under reduced pressure to obtain 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl)diol.

[0041] (2) Under nitrogen atmosphere, 4.3 mmol of terephthalic acid, 2 mmol of ethylene glycol and 2.2 mmol of 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl)diol were added to the reactor, mixed evenly, and then esterification reaction was carried out at 210 ° C for 12 hours. Then, 0.4 mmol of antimony trioxide as a catalyst and 0.16 mmol of triphenyl phosphite as a heat stabilizer were added. The pressure in the reactor was reduced to 10 Pa by vacuum pumping, and polycondensation reaction was carried out at 250 ° C for 5 hours. The product was squeezed out with nitrogen, cooled and solidified in a water tank and pelletized to obtain fluorinated polyester chips.

[0042] (3) The fluorinated polyester chips were placed in a drying oven at 100°C for 12 h, and then placed in a single-screw melt spinning machine for melt spinning. The spinning temperature was 245°C, the spinning speed was 230 r / min, the temperatures of the screw zones 1 to 4 of the single-screw melt spinning machine were set to 245°C, 250°C, 255°C, and 270°C, respectively, and the head temperature was 280°C. The chips were then placed in a fiber stretching instrument for hot stretching at a temperature of 115°C and a time of 10 min to obtain modified polyester fibers.

[0043] Example 4

[0044] (1) Under nitrogen atmosphere, 12 mmol of 2,2'-[1,4-phenylenebis(oxymethylene)]dioxirane and 72 mL of xylene were added to a reaction flask equipped with a reflux condenser. After stirring evenly, 25.8 mmol of 2H,2H,3H,3H-heptadecafluoroundecanoic acid and 27.6 mmol of triethylamine were added. The mixture was reacted at 125°C for 6 h and distilled under reduced pressure to obtain 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl)diol.

[0045] (2) Under nitrogen atmosphere, 16.8 mmol of terephthalic acid, 8 mmol of ethylene glycol and 8.4 mmol of 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl)diol were added to the reactor, mixed evenly, and then esterification reaction was carried out at 225 ° C for 7 h. Then, 0.96 mmol of antimony trioxide as a catalyst and 0.56 mmol of triphenyl phosphite as a heat stabilizer were added. The pressure in the reactor was reduced to 12 Pa by vacuum, and polycondensation reaction was carried out at 270 ° C for 3 h. The product was squeezed out with nitrogen, cooled and solidified in a water tank and pelletized to obtain fluorinated polyester chips.

[0046] (3) The fluorinated polyester chips were placed in a drying oven at 115°C for 9 hours and then placed in a single-screw melt spinning machine for melt spinning. The spinning temperature was 260°C and the spinning speed was 235 r / min. The temperatures of the screw zones 1 to 4 of the single-screw melt spinning machine were set to 250°C, 260°C, 265°C, and 265°C, respectively, and the head temperature was 270°C. The chips were then placed in a fiber stretching instrument for hot stretching at a temperature of 130°C and a time of 9 minutes to obtain modified polyester fibers.

[0047] Example 5

[0048] (1) Under nitrogen atmosphere, 50 mmol of 2,2'-[1,4-phenylenebis(oxymethylene)]dioxirane and 350 mL of xylene were added to a reaction flask equipped with a reflux condenser. After stirring evenly, 109 mmol of 2H,2H,3H,3H-heptadecafluoroundecanoic acid and 115 mmol of triethylamine were added. The mixture was reacted at 125 °C for 6 h and distilled under reduced pressure to obtain 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl)diol.

[0049] (2) Under nitrogen atmosphere, 53 mmol of terephthalic acid, 25 mmol of ethylene glycol and 26.25 mmol of 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl)diol were added to the reactor, mixed evenly, and then esterification reaction was carried out at 220 ° C for 10 hours. Then, 3.5 mmol of catalyst antimony trioxide and 1.5 mmol of heat stabilizer triphenyl phosphite were added. The pressure in the reactor was reduced to 12 Pa by vacuum, and polycondensation reaction was carried out at 270 ° C for 3 hours. The product was squeezed out with nitrogen, cooled and solidified in a water tank and pelletized to obtain fluorinated polyester chips.

[0050] (3) The fluorinated polyester chips were placed in a drying oven at 115°C for 9 hours and then placed in a single-screw melt spinning machine for melt spinning. The spinning temperature was 250°C and the spinning speed was 240 r / min. The temperatures of the screw zones 1 to 4 of the single-screw melt spinning machine were set to 255°C, 250°C, 265°C, and 265°C, respectively. The head temperature was 270°C. The chips were then placed in a fiber stretching instrument for hot stretching at a temperature of 130°C and a time of 8 minutes to obtain modified polyester fibers.

[0051] Comparative Example 1

[0052] (1) Under nitrogen atmosphere, 25 mmol of 2,2'-[1,4-phenylenebis(oxymethylene)]dioxirane and 175 mL of xylene were added to a reaction flask equipped with a reflux condenser. After stirring evenly, 52.5 mmol of undecanoic acid and 55 mmol of triethylamine were added. The mixture was reacted at 120°C for 5 h and then distilled under reduced pressure to obtain 2,2'-[1,4-phenylenebis(oxymethylene)]bis(undecanediol)diol, the structural formula of which is

[0053]

[0054] (2) Under nitrogen atmosphere, 21 mmol of terephthalic acid, 10 mmol of ethylene glycol and 10.5 mmol of 2,2'-[1,4-phenylenebis(oxymethylene)]bis(undecayl)diol were added to the reactor, mixed evenly, and then esterification reaction was carried out at 220 ° C for 10 hours. Then, 1.5 mmol of antimony trioxide catalyst and 0.6 mmol of triphenyl phosphite heat stabilizer were added. The pressure in the reactor was reduced to 15 Pa by vacuum, and polycondensation reaction was carried out at 260 ° C for 3 hours. The product was squeezed out with nitrogen, cooled and solidified in a water tank and pelletized to obtain polyester chips.

[0055] (3) The polyester chips were placed in a drying oven at 110°C for 9 hours and then placed in a single-screw melt spinning machine for melt spinning. The spinning temperature was 260°C and the spinning speed was 240 r / min. The temperatures of the screw zones 1 to 4 of the single-screw melt spinning machine were set to 250°C, 255°C, 260°C, and 270°C, respectively, and the head temperature was 275°C. The chips were then placed in a fiber stretching instrument for hot stretching at a temperature of 125°C and a time of 8 minutes to obtain modified polyester fibers.

[0056] Alkali resistance test: The prepared modified polyester fiber was completely immersed in a sodium hydroxide solution with a pH value of 13, and the temperature of the alkaline solution was controlled at 25°C. After soaking for 28 days, the sample was taken out and rinsed with clean water, placed in a dryer, and dried at 25°C. The tensile strength was tested with a fiber strength testing machine, and each sample was measured three times to obtain the average value.

[0057]

[0058] From the test results in the above table, it can be seen that the introduction of fluorine-containing groups in polyester fibers effectively improves the alkali resistance of polyester fibers. After immersion in a sodium hydroxide solution with a pH of 13 for 28 days, the tensile strength of the modified polyester fiber did not change significantly. However, the comparative example 1 does not contain organic fluorine, and its tensile strength decreases significantly after immersion in sodium hydroxide. This is because after the introduction of organic fluorine into the polyester fiber, the carbon chain is surrounded by a series of stable fluorine atoms. The shielding effect of the electron cloud of fluorine on the main chain is stronger than that of hydrogen atoms, making it difficult for any reaction reagent to insert, showing excellent chemical resistance; at the same time, the fluorine-carbon chain with lower surface free energy is more easily enriched on the surface, thereby improving the hydrophobic and oleophobic properties and acid and alkali resistance of the polyester. Therefore, the prepared modified polyester fiber solves the problem that conventional polyester fibers can only be used in asphalt concrete and alkali-free concrete due to poor alkali resistance, and broadens the further application of polyester fibers in concrete.

[0059] Example 6

[0060] 7.52 g of modified polyester fiber (prepared in Example 1), 3 g of polycarboxylate water reducer and 160 g of water were added to a mixer and stirred at 55 ° C for 15 min. Then, 320 g of cement, 125 g of slag powder and 750 g of yellow sand were added at 35 ° C and stirred for 25 min. Finally, 1100 g of crushed gravel with a particle size of 15 mm and 50 g of fly ash were added and stirred at 25 ° C for 30 min to obtain anti-seepage and waterproof fiber-reinforced concrete.

[0061] Example 7

[0062] 14.78 g of modified polyester fiber (prepared in Example 2), 2 g of polycarboxylate water reducer and 150 g of water were added to a mixer and stirred at 60 ° C for 10 min. Then, 300 g of cement, 100 g of slag powder and 650 g of yellow sand were added at 40 ° C and stirred for 20 min. Finally, 1180 g of crushed gravel with a particle size of 20 mm and 80 g of fly ash were added and stirred at 35 ° C for 25 min to obtain anti-seepage and waterproof fiber-reinforced concrete.

[0063] Example 8

[0064] 24.16 g of modified polyester fiber (prepared in Example 3), 5 g of polycarboxylate water reducer and 180 g of water were added to a mixer and stirred at 45 ° C for 20 min. Then, 350 g of cement, 140 g of slag powder and 650 g of yellow sand were added at 30 ° C and stirred for 30 min. Finally, 1050 g of crushed gravel with a particle size of 25 mm and 10 g of fly ash were added and stirred at 20 ° C for 25 min to obtain anti-seepage and waterproof fiber reinforced concrete.

[0065] Example 9

[0066] 30.53 g of modified polyester fiber (prepared in Example 4), 4 g of polycarboxylate water reducer and 170 g of water were added to a mixer and stirred at 55 ° C for 12 min. Then, 310 g of cement, 130 g of slag powder and 720 g of yellow sand were added at 40 ° C and stirred for 25 min. Finally, 1150 g of crushed gravel with a particle size of 15 mm and 60 g of fly ash were added and stirred at 35 ° C for 30 min to obtain anti-seepage and waterproof fiber-reinforced concrete.

[0067] Example 10

[0068] 36.95 g of modified polyester fiber (prepared in Example 5), 3 g of polycarboxylate water reducer and 170 g of water were added to a mixer and stirred at 50 ° C for 20 min. Then, 330 g of cement, 120 g of slag powder and 720 g of yellow sand were added at 30 ° C and stirred for 30 min. Finally, 1080 g of crushed gravel with a particle size of 10 mm and 40 g of fly ash were added and stirred at 20 ° C for 40 min to obtain anti-seepage and waterproof fiber-reinforced concrete.

[0069] Comparative Example 2

[0070] 7.52 g of modified polyester fiber (prepared by Comparative Example 1), 3 g of polycarboxylate water reducer and 160 g of water were added to a mixer and stirred at 55 ° C for 15 min. Then, 320 g of cement, 125 g of slag powder and 750 g of yellow sand were added at 35 ° C and stirred for 25 min. Finally, 1100 g of crushed gravel with a particle size of 15 mm and 50 g of fly ash were added and stirred at 25 ° C for 30 min to obtain fiber reinforced concrete.

[0071] Comparative Example 3

[0072] 3 g of polycarboxylate water reducer and 160 g of water were added to the mixer and stirred at 55° C. for 15 min. Then, 320 g of cement, 125 g of slag powder and 750 g of yellow sand were added and stirred at 35° C. for 25 min. Finally, 1100 g of crushed gravel with a particle size of 15 mm and 50 g of fly ash were added and stirred at 25° C. for 30 min to obtain concrete.

[0073] Preparation of test specimens: According to JTGE30-2005 "Test Procedures for Cement and Cement Concrete in Highway Engineering", the prepared concrete was made into a truncated cone specimen with a top diameter of 175 mm, a bottom diameter of 185 mm, and a height of 150 mm.

[0074] Anti-seepage and waterproofing test: The prepared concrete cone specimens were placed in a standard curing room with a temperature of 20°C and a humidity of 95% and cured for 28 days. The sealing wax was taken out and placed on a concrete permeameter. The water pressure was increased to 1 MPa within 10 minutes. After 24 hours of water pressure, the specimens were taken out and subjected to a splitting tensile test on a pressure testing machine. The water seepage height was then measured.

[0075] Water seepage height (cm) Example 6 6.48 Example 7 4.32 Example 8 3.10 Example 9 1.95 Example 10 1.20 Comparative Example 2 10.01 Comparative Example 3 13.62

[0076] Concrete will generate tensile stress inside due to plastic shrinkage, drying shrinkage, temperature shrinkage, carbonization shrinkage and other reasons. When the stress exceeds the tensile strength of concrete, a large number of micro cracks and cracks will be generated. From the test results in the above table, it can be seen that with the increase of the content of modified polyester fiber in concrete, the water seepage height of the concrete specimen is significantly reduced, and the anti-seepage and waterproof performance is significantly enhanced. This is because, on the one hand, the modified polyester fiber contains fluorine-containing groups with excellent hydrophobicity, which can be enriched on the fiber surface and have a certain waterproof effect; on the other hand, the modified polyester fiber forms a cross-net support system in the concrete matrix, which plays the role of supporting aggregates and, to a certain extent, prevents water from seeping into the concrete. It stops the settlement of materials, reduces the water separation phenomenon on the concrete surface, and effectively prevents the volume shrinkage during the plastic period caused by water loss on the concrete surface, thereby inhibiting the occurrence of plastic cracks. At the same time, the modified polyester fiber can limit the generation of new cracks, reduce the number of crack sources, and have a strong binding effect on existing cracks, thereby reducing the probability of through cracks inside the concrete and ensuring the continuity and integrity of the concrete matrix. In addition, the addition of modified polyester fiber can block the capillary channels in the concrete, making the migration of water difficult and the crack refinement effect more significant. Therefore, the anti-seepage and waterproof performance increases with the increase of fiber content.

[0077] Frost resistance test: According to GB / T 50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete", after the specimens are formed, they are placed in a standard curing room for curing. 4 days before the test age, the specimens are taken out and immersed in 20°C water. Before the test, the specimens are taken out of the water, the surface water is wiped off, and the mass is measured and weighed as the starting value for evaluating frost resistance. The test adopts the rapid freeze-thaw method. Each freeze-thaw cycle is about 2.5 hours. The temperature at the center of the specimen is between -15°C and 10°C. After 50 and 200 freeze-thaw cycles, the mass loss rate of the specimen is calculated, and its frost resistance is evaluated.

[0078]

[0079] As can be seen from the test results in the above table, with the increase of the modified polyester fiber content, the mass loss rate of concrete gradually decreases. Comparative Example 3 is ordinary concrete without polyester fiber. After 200 freeze-thaw cycles, its mass loss rate reaches 6.28%, which is much higher than that of the embodiment. This is because there is a strong bonding force and mechanical meshing force between the modified polyester fiber and the cement-based material interface. There are tens of millions of high-tensile strength fibers in each cubic meter of concrete, which produces a comprehensive reinforcement effect, weakens the shrinkage stress of the concrete, greatly reduces the shrinkage cracks of the concrete, and plays a role in blocking the development of microcracks in the block, thereby effectively preventing the peeling of the concrete surface material during the freeze-thaw process. At the same time, during the freeze-thaw cycle, the modified polyester fiber alleviates part of the internal temperature stress caused by temperature changes, thereby preventing the development of temperature cracks, thereby improving the frost resistance of the concrete.

[0080] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing anti-seepage and waterproof fiber reinforced concrete, characterized in that: The concrete comprises the following ingredients in parts by weight: 300-350 parts of cement, 150-180 parts of water, 1050-1180 parts of aggregate, 100-140 parts of slag powder, 650-800 parts of yellow sand, 10-80 parts of fly ash and 2-5 parts of water reducing agent, and also comprises modified polyester fiber accounting for 0.3-1.5% of the total weight of the above components; The preparation method comprises: adding modified polyester fiber, polycarboxylate water-reducing agent and water into a mixer, stirring at a temperature of 45-60° C. for 10-20 minutes, then adding cement, slag powder and yellow sand at a temperature of 30-40° C. for 20-30 minutes, and finally adding aggregate and fly ash, stirring at a temperature of 20-35° C. for 25-40 minutes, to obtain anti-seepage and waterproof fiber-reinforced concrete; The aggregate is crushed gravel with a particle size of 10-25 mm; The water reducer is a polycarboxylate water reducer; The preparation method of the modified polyester fiber is: (1) Under a nitrogen atmosphere, 2,2'-[1,4-phenylenebis(oxymethylene)]dioxirane and xylene were added to a reaction flask equipped with a reflux condenser, and after stirring evenly, 2H,2H,3H,3H-heptadecafluoroundecanoic acid and triethylamine were added, and the mixture was stirred for reaction. After the reaction was completed, the mixture was distilled under reduced pressure to obtain 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl)diol; (2) Under a nitrogen atmosphere, terephthalic acid, ethylene glycol and 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl)diol are added to a reactor, mixed evenly, and then an esterification reaction is carried out. Then, a catalyst antimony trioxide and a heat stabilizer triphenyl phosphite are added, and the pressure in the reactor is reduced to 10-20 Pa by vacuuming to carry out a polycondensation reaction. After the reaction is completed, the reactor is squeezed out with nitrogen, cooled and solidified in a water tank, and pelletized to obtain fluorinated polyester chips; (3) drying the fluorinated polyester chips in a drying oven at 100-120° C. for 5-12 h, placing them in a single-screw melt spinning machine for melt spinning at a spinning temperature of 245-270° C. and a spinning speed of 230-250 r / min, and then placing them in a fiber stretching apparatus for heat stretching to obtain modified polyester fibers; In the step (1), the ratio of 2,2'-[1,4-phenylenebis(oxymethylene)]dioxirane, 2H,2H,3H,3H-heptadecafluoroundecanoic acid, and triethylamine is 1 mol:(2.05-2.2) mol:(2.1-2.4) mol; In the step (2), the ratio of terephthalic acid, ethylene glycol, 2,2'-[1,4-phenylenebis(oxymethylene)]bis(heptadecafluoroundecyl)diol, antimony trioxide as a catalyst, and triphenyl phosphite as a thermal stabilizer is (2.05-2.15) mol: 1 mol: (0.95-1.1) mol: (0.1-0.2) mol: (0.05-0.08) mol; In the step (3), the heat stretching temperature is 115-130° C., and the heat stretching time is 5-10 min.

2. The method for preparing anti-seepage and waterproof fiber reinforced concrete according to claim 1, characterized in that: In the step (1), the reaction temperature is 110-130° C. and the reaction time is 3-8 h.

3. The method for preparing anti-seepage and waterproof fiber reinforced concrete according to claim 1, characterized in that: In the step (2), the esterification reaction temperature is 210-230° C., and the esterification reaction time is 5-12 h.

4. The method for preparing anti-seepage and waterproof fiber reinforced concrete according to claim 1, characterized in that: In the step (2), the polycondensation reaction temperature is 250-280° C., and the polycondensation reaction time is 2-5 hours.

5. The method for preparing anti-seepage and waterproof fiber reinforced concrete according to claim 1, characterized in that: In the step (3), the temperatures of screw zones 1 to 4 of the single-screw melt spinning machine are set to 245-255°C, 250-260°C, 255-265°C, and 260-270°C, respectively, and the head temperature is 270-280°C.

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