CN116768579A - Anti-cracking concrete for assembled building and preparation method thereof - Google Patents
Anti-cracking concrete for assembled building and preparation method thereof Download PDFInfo
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- 239000004567 concrete Substances 0.000 title claims abstract description 101
- 238000005336 cracking Methods 0.000 title claims abstract description 72
- 238000002360 preparation method Methods 0.000 title claims abstract description 8
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims abstract description 82
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 52
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical class [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 41
- 238000003756 stirring Methods 0.000 claims abstract description 41
- 239000000835 fiber Substances 0.000 claims abstract description 30
- 229910000019 calcium carbonate Inorganic materials 0.000 claims abstract description 29
- 108010022355 Fibroins Proteins 0.000 claims abstract description 28
- 229910021389 graphene Inorganic materials 0.000 claims abstract description 26
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- 239000004964 aerogel Substances 0.000 claims abstract description 25
- 238000002156 mixing Methods 0.000 claims abstract description 23
- 239000000843 powder Substances 0.000 claims abstract description 23
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 20
- 239000002131 composite material Substances 0.000 claims abstract description 19
- 239000012752 auxiliary agent Substances 0.000 claims abstract description 18
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 claims abstract description 15
- 235000021355 Stearic acid Nutrition 0.000 claims abstract description 14
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000008117 stearic acid Substances 0.000 claims abstract description 14
- 229920005646 polycarboxylate Polymers 0.000 claims abstract description 13
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000004576 sand Substances 0.000 claims abstract description 11
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 10
- 239000010703 silicon Substances 0.000 claims abstract description 10
- 239000002893 slag Substances 0.000 claims abstract description 10
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 7
- 239000008030 superplasticizer Substances 0.000 claims abstract description 7
- 239000011398 Portland cement Substances 0.000 claims abstract description 5
- 239000008367 deionised water Substances 0.000 claims description 28
- 229910021641 deionized water Inorganic materials 0.000 claims description 28
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 claims description 23
- 239000003245 coal Substances 0.000 claims description 22
- 239000000243 solution Substances 0.000 claims description 19
- 238000000034 method Methods 0.000 claims description 18
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 16
- 238000009210 therapy by ultrasound Methods 0.000 claims description 16
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 15
- 239000011259 mixed solution Substances 0.000 claims description 13
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 12
- 238000001035 drying Methods 0.000 claims description 12
- 238000001914 filtration Methods 0.000 claims description 12
- 239000002245 particle Substances 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 9
- 238000005406 washing Methods 0.000 claims description 9
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 8
- 238000010041 electrostatic spinning Methods 0.000 claims description 8
- 235000019253 formic acid Nutrition 0.000 claims description 8
- 239000011575 calcium Substances 0.000 claims description 7
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 6
- 125000002091 cationic group Chemical group 0.000 claims description 6
- 238000001816 cooling Methods 0.000 claims description 6
- 239000006185 dispersion Substances 0.000 claims description 6
- 238000000227 grinding Methods 0.000 claims description 6
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- 239000011148 porous material Substances 0.000 claims description 6
- 238000002791 soaking Methods 0.000 claims description 6
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical class [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 5
- 239000000654 additive Substances 0.000 claims description 4
- 239000011248 coating agent Substances 0.000 claims description 4
- 238000000576 coating method Methods 0.000 claims description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 3
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims description 3
- 230000000996 additive effect Effects 0.000 claims description 3
- 229910052791 calcium Inorganic materials 0.000 claims description 3
- 239000001110 calcium chloride Substances 0.000 claims description 3
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- 238000004108 freeze drying Methods 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 239000004570 mortar (masonry) Substances 0.000 claims description 3
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 3
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 abstract description 18
- 239000000292 calcium oxide Substances 0.000 abstract description 18
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 abstract description 18
- CJZGTCYPCWQAJB-UHFFFAOYSA-L calcium stearate Chemical compound [Ca+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O CJZGTCYPCWQAJB-UHFFFAOYSA-L 0.000 abstract description 8
- 239000008116 calcium stearate Substances 0.000 abstract description 8
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- 238000006243 chemical reaction Methods 0.000 abstract description 4
- 238000000354 decomposition reaction Methods 0.000 abstract description 4
- 238000009987 spinning Methods 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 29
- 238000006703 hydration reaction Methods 0.000 description 11
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- 238000001523 electrospinning Methods 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- 239000003638 chemical reducing agent Substances 0.000 description 7
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- 239000002994 raw material Substances 0.000 description 5
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- 238000010899 nucleation Methods 0.000 description 4
- 229910021487 silica fume Inorganic materials 0.000 description 4
- 239000003469 silicate cement Substances 0.000 description 4
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 3
- 238000004321 preservation Methods 0.000 description 3
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 2
- 108010013296 Sericins Proteins 0.000 description 2
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- 238000009835 boiling Methods 0.000 description 2
- 239000000920 calcium hydroxide Substances 0.000 description 2
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 2
- 229910001424 calcium ion Inorganic materials 0.000 description 2
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 2
- 150000001768 cations Chemical class 0.000 description 2
- 230000001360 synchronised effect Effects 0.000 description 2
- 239000005995 Aluminium silicate Substances 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 150000001335 aliphatic alkanes Chemical group 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
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- 125000000524 functional group Chemical group 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
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- 239000012779 reinforcing material Substances 0.000 description 1
- SCPYDCQAZCOKTP-UHFFFAOYSA-N silanol Chemical compound [SiH3]O SCPYDCQAZCOKTP-UHFFFAOYSA-N 0.000 description 1
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Landscapes
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The invention discloses anti-cracking concrete for an assembled building and a preparation method thereof, belonging to the technical field of anti-cracking concrete, and comprising the following steps: the stearic acid coated calcium carbonate is doped into the silk fibroin solution, and the composite fiber is obtained through spinning; mixing the modified graphene oxide with silicon micropowder to prepare aerogel, so as to obtain an anti-cracking auxiliary agent; mixing Portland cement, sand, stones, slag powder, composite fibers, an anti-cracking agent and an anti-cracking auxiliary agent, adding a polycarboxylate superplasticizer and water, and stirring to obtain the anti-cracking concrete. The calcium stearate can form a waterproof layer along the capillary holes, so that moisture is reduced to pass through the capillary holes, and cracks formed by the reaction expansion of the calcium stearate and free calcium oxide are avoided; the hydrophobic layer is arranged on the surface of the fiber, so that the decomposition of the composite fiber in the alkaline concrete can be reduced; the porous aerogel structure can effectively reduce the thermal conductivity of concrete, and the silica micropowder is used as a framework in the aerogel, so that the problem that the concrete is easy to crack due to the fact that graphene oxide is easy to be fragile after high-temperature treatment is avoided.
Description
Technical Field
The invention relates to the technical field of anti-cracking concrete, in particular to anti-cracking concrete for an assembled building and a preparation method thereof.
Background
The concrete is a composite material formed by cementing aggregate into a whole by using cementing materials, cement is adopted as the cementing materials, sand and stone are adopted as the aggregate, the sand and the stone are matched with water, additives and admixtures according to a certain proportion, and the concrete is obtained by stirring.
The calcium carbonate comprises heavy calcium carbonate and light calcium carbonate, wherein the heavy calcium carbonate has stronger hardness, can enhance the mechanical property of the concrete and has better waterproof property; the heat insulation performance of the concrete can be enhanced by adding the porous material into the concrete, the heat insulation performance of the concrete is widely applied to the field of construction, the brittleness of the porous material needs to be considered, and the cracking of the concrete caused by the crushing of the porous material in the concrete under the impact of pressure is avoided; the mechanical property and compressive strength of the concrete can be effectively enhanced by adding the fiber into the concrete, and most of the treatment of the waste silk and the textile thereof still adopts the modes of incineration, burial and the like, so that the resource is greatly wasted, and the fiber is prepared by adopting the silk fibroin, so that the resource can be solved.
The concrete is used as a novel building material, the aggregate of the novel building material can be obtained locally, the member is easy to form and has hydraulic property, but the hydration speed of free calcium oxide in the concrete is low, the free calcium oxide component still generates hydration reaction when meeting water after the cement is solidified, and the free calcium oxide component expands in the concrete to cause the cracking of the concrete.
Disclosure of Invention
The invention aims to provide anti-cracking concrete for an assembled building and a preparation method thereof: the stearic acid is used for coating the calcium carbonate, and the calcium stearate is formed on the surface of the calcium carbonate, so that a waterproof layer can be formed along capillary holes, moisture is reduced from passing through the capillary holes, and cracks formed by reaction expansion of the calcium stearate and free calcium oxide are avoided; the modified calcium carbonate is doped into the silk fibroin solution, the modified calcium carbonate can enhance the mechanical strength of silk fibroin fibers, and the surface of the fibers contains a hydrophobic layer, so that the decomposition of composite fibers in alkaline concrete can be reduced; the cation modified coal-containing metakaolin is utilized, and then the cation modified coal-containing metakaolin is adsorbed on the graphene oxide sheet layer, so that the cement hydration reaction is promoted, the nucleation effect of the graphene oxide aerogel can be enhanced, and the compressive strength of the graphene oxide aerogel is improved; the modified graphene oxide and the silicon micropowder form aerogel, the porous structure can effectively reduce the thermal conductivity of concrete, the porous structure has good heat insulation performance, the silicon micropowder has good mechanical strength, and the porous structure is used as a framework in the aerogel, so that the problem that the concrete is easy to crack due to brittleness of the graphene oxide after high-temperature treatment is avoided.
The invention aims to solve the technical problems: the concrete is used as a novel building material, the aggregate of the novel building material can be obtained locally, the member is easy to form and has hydraulic property, but the hydration speed of free calcium oxide in the concrete is low, the free calcium oxide component still generates hydration reaction when meeting water after the cement is solidified, and the free calcium oxide component expands in the concrete to cause the cracking of the concrete.
In order to achieve the above purpose, the present invention provides the following technical solutions:
the preparation method of the anti-cracking concrete for the assembled building comprises the following steps:
s1, coating calcium carbonate by stearic acid to obtain modified calcium carbonate, wherein the modified calcium carbonate is prepared by the following steps:
adding 0.2g of calcium carbonate into 10mL of deionized water, placing in a water bath kettle at 30 ℃, carrying out ultrasonic treatment for 3min to obtain a dispersion liquid, adding 0.5g of stearic acid into 30mL of deionized water, uniformly stirring, placing in the dispersion liquid, carrying out ultrasonic treatment for 3min, placing in a baking oven at 105 ℃ for drying overnight to remove water, and grinding into fine powder by adopting a mortar and a pestle to obtain modified calcium carbonate;
wherein, calcium carbonate is dispersed in deionized water, and hydrolysis occurs in the calcium carbonate as an outer layer, so that calcium ions contained in the outer layer can react with carboxyl groups of stearic acid to form calcium stearate, and the stearic acid is coated on the surface of the calcium carbonate.
S2, doping modified calcium carbonate into a silk fibroin solution, and carrying out electrostatic spinning to obtain composite fibers, namely an anticracking agent, wherein the composite fibers are prepared by the following steps:
adding 0.8g of modified calcium carbonate into 10mL of formic acid, carrying out ultrasonic treatment for 10min, adding 13g of silk fibroin solution, stirring for 3h to obtain a mixed solution, placing the mixed solution into an ejector, carrying out electrostatic spinning under the conditions that the electrostatic spinning voltage is 26KV and the flow rate of the mixed solution is 2.4mL/min, and collecting the electrostatic spinning to obtain the composite fiber, namely the anti-cracking agent.
The modified calcium carbonate is dispersed in the formic acid solvent, so that the modified calcium carbonate is better dispersed in the silk fibroin fibers, the surface of the modified calcium carbonate contains a hydrophobic long-chain alkane structure, a hydrophobic layer is formed on the surface of the fibers, and the modified calcium carbonate has better alkali resistance, so that the silk fibroin fibers are not easy to decompose in alkaline concrete.
Further, the silk fibroin solution is prepared by the following steps:
adding 0.2g of silk into 20mL of sodium carbonate solution, stirring at 100 ℃ for 1h to degumm the silk, taking out, washing with deionized water for 5 times to remove sericin in the silk, drying in a baking oven at 40 ℃ for 10min, dissolving in 0.85g of calcium chloride, 10mL of ethanol and 20mL of deionized water, uniformly stirring, dialyzing, filtering and freeze-drying to obtain silk fibroin, and dissolving the silk fibroin in formic acid with the mass fraction of 98% to obtain silk fibroin solution.
Further, the grain size of the calcium carbonate is 0.01-0.5 mu m, and the calcium content is more than or equal to 65 percent.
Further, the length of the composite fiber is 5-10mm, and the diameter is 0.2-0.3mm.
S3, utilizing the cationic modified coal-containing metakaolin, adsorbing the cationic modified coal-containing metakaolin onto graphene oxide sheets to obtain modified graphene oxide, mixing the modified graphene oxide with silicon micropowder to prepare aerogel, and obtaining an anti-cracking auxiliary agent, wherein the anti-cracking auxiliary agent is prepared by the following steps:
A1. mixing 15mL of saturated calcium hydroxide solution with 30mL of deionized water, stirring for 3min, adding 1.5g of metakaolin containing coal, stirring for 30min, soaking for 24h at 30 ℃, filtering, washing with deionized water for 3 times, drying in a 70 ℃ oven for 15min, taking out, grinding in a grinder to obtain powder, wherein the particle size of the powder is 2-3 mu m, adding 0.2g of graphene oxide into 50mL of deionized water, performing ultrasonic treatment for 5min to ensure that the graphene oxide is fully dispersed, adding 0.15g of powder, stirring for 2min at 4000rpm, soaking for 5min, filtering, washing with deionized water for 2 times, and drying in a 70 ℃ oven for 20min to obtain modified graphene oxide;
wherein, hydroxyl groups on the surface of the metakaolin containing coal react with calcium ions in the calcium hydroxide to deprotonate silanol and aluminum alcohol groups on the surface of the metakaolin containing coal, so that Si-O-Ca is formed on the surface of the metakaolin containing coal + /Al-O-Ca + The structure realizes that the surface of the metakaolin containing coal has positive charges; the surface of the graphene oxide sheet layer contains hydroxyl, carboxyl and other functional groups, the graphene oxide sheet layer is negatively charged in an aqueous solution, and can be electrostatically reacted with the coal-containing metakaolin with positive charges, so that the coal-containing metakaolin is adsorbed on the graphene oxide sheet layer, the coal-containing metakaolin can promote cement hydration, and the nucleation effect of the graphene oxide aerogel can be enhanced.
A2. Adding 0.8g of modified graphene oxide and 0.6 silicon micropowder into 50mL of deionized water, carrying out ultrasonic treatment for 30min, adding 0.2mL of ethylene glycol and 1mL of ethanol, stirring for 30 mm, heating to 200 ℃, stirring for 30min to remove unreacted organic solvent, cooling to room temperature, filtering to obtain a gel-like substance, treating the gel-like substance at 800 ℃ for 2h under nitrogen atmosphere to eliminate water in the gel-like substance, and cooling to room temperature to obtain an anti-cracking auxiliary agent;
the positive charge on the surface of the modified graphene oxide and ethylene glycol are subjected to electrostatic action, and the ethylene glycol and hydroxyl expressed by the silica micropowder are combined through chemical bonds to form a gel-like substance of the graphene oxide coated silica micropowder, and further, the graphene oxide aerogel taking the silica micropowder as a framework is formed after the treatment at 800 ℃ by taking inert gas as a reducing agent, so that cracks of concrete due to brittleness of the graphene oxide after the high-temperature treatment are avoided.
Further, the particle size of the silica micropowder is 10-40nm, and the specific surface area is 0.02m 2 /kg。
Further, the grain diameter of the cracking resistance auxiliary agent is 10-30 mu m, and the pore diameter is 50-100nm.
S4, mixing silicate cement, sand, stones, slag powder, an anti-cracking agent and an anti-cracking auxiliary agent, adding a polycarboxylate superplasticizer and deionized water, stirring and mixing to prepare anti-cracking concrete, wherein the anti-cracking concrete is prepared by the following steps:
step 1, preparing 349g of Portland cement, 681g of sand, 812g of stones, 113g of slag powder, 32g of cracking resistance agent and 26g of cracking resistance auxiliary agent;
and 2, mixing and stirring the raw materials for 3min, adding 9g of the polycarboxylate superplasticizer and 106g of water, and continuously stirring for 10min to obtain the anti-cracking concrete.
Further, the Portland cement model is PO52.5, and the specific surface area is 386.5m 2 The 28d compressive strength per kg was 56.3MPa.
Further, the slag powder is S95 grade slag powder with a specific surface area of 450m 2 The 28d activity index was 95% per kg.
Further, the stones are crushed stone with the continuous grading of 5-10mm, crushed stone with the continuous grading of 5-20mm and crushed stone with the continuous grading of 5-31.5mm, and the mass ratio of the crushed stone to the crushed stone is (0.5-1.5) to (1-2) to (1.7-1.9).
Further, the fineness modulus of the sand is 3.7-1.6, and the grain diameter is 0.25-2.5mm.
Further, the polycarboxylate water reducer is one of PCE-102 polycarboxylate water reducer, PCE-101 polycarboxylate water reducer and PCE-103 polycarboxylate water reducer.
Compared with the prior art, the invention has the following beneficial effects:
(1) According to the technical scheme, the calcium carbonate can enhance the mechanical property of concrete in the concrete, meanwhile, the economic benefit of the concrete can be improved, stearic acid reacts with the calcium carbonate, calcium stearate is formed on the surface of the calcium carbonate, the formed calcium stearate can form a waterproof layer along capillary holes, the contact angle between the hole wall and water drops is increased, after the concrete is solidified, moisture is reduced to pass through the capillary holes, cracks formed by reaction expansion with free calcium oxide are avoided, in addition, the stearate on the surface of the calcium carbonate can reduce the intercept of the cement in the concrete, the contractibility of the concrete is reduced, the cracking resistance of the concrete is improved, the hydrophobic structure contained on the surface of the calcium carbonate improves the impermeability of the concrete, and the corrosion resistance of the concrete is further enhanced;
(2) According to the technical scheme, the modified calcium carbonate is doped into the silk fibroin to form the composite fiber, on one hand, the modified calcium carbonate has strong mechanical properties, the mechanical strength of the silk fibroin fiber can be enhanced, the surface of the fiber contains a hydrophobic layer, the decomposition of the composite fiber in alkaline concrete can be reduced, and on the other hand, the composite fiber can pass through micro cracks in the concrete, so that the cracks and shrinkage of the concrete are effectively controlled, and the crack resistance of the concrete is improved;
(3) According to the technical scheme, the coal-containing metakaolin reacts with the calcium hydroxide, so that the positively charged coal-containing metakaolin can be subjected to electrostatic adsorption with graphene oxide to promote cement hydration reaction, the nucleation effect of the graphene oxide aerogel can be enhanced, and the compressive strength of the graphene oxide aerogel can be improved; the modified graphene oxide is adopted to prepare the porous aerogel, so that the thermal conductivity of concrete can be effectively reduced, the thermal insulation performance is good, meanwhile, the added silica powder has good mechanical strength, the porous aerogel is taken as a framework in the aerogel, the cracking of the concrete caused by the brittleness of the graphene oxide after high-temperature treatment is avoided, the strength and durability of the aerogel are improved, in addition, in the curing process of the aerogel, silicon powder can be released to participate in hydration reaction of free calcium oxide, the hydration rate of the free calcium oxide is improved, the content of free calcium oxide in the cured concrete is reduced, the cracking resistance of the concrete is improved, and in addition, the kaolin adsorbed on the surface of the aerogel contains Si-O-Ca + /Al-O-Ca + The structure can interact with the anionic polycarboxylate water reducer to improve the dispersibility of the aerogel in a cement matrix.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The component contents of the coal-containing metakaolin used in the examples of the present invention are shown in table 1:
TABLE 1
。
Example 1, modified calcium carbonate, was prepared by the following steps:
adding 0.2g of heavy calcium carbonate into 10mL of deionized water, placing in a water bath kettle at 30 ℃, carrying out ultrasonic treatment for 3min to obtain a dispersion liquid, adding 0.5g of stearic acid into 30mL of deionized water, uniformly stirring, placing in the dispersion liquid, carrying out ultrasonic treatment for 3min, placing in a 105 ℃ oven for drying overnight to remove water, and grinding into fine powder by adopting a mortar and pestle to obtain the modified calcium carbonate, wherein the particle size of the heavy calcium carbonate is 0.25 mu m, and the calcium content is more than or equal to 65%.
Comparative example 1
This comparative example differs from example 1 in that the calcium carbonate has not been surface modified with stearic acid.
Example 2, crack resistant agent, was prepared by the following steps:
A1. adding 0.2g of silk into 20mL of sodium carbonate solution, stirring at 100 ℃ for 1h to degumm the silk, taking out, washing with deionized water for 5 times to remove sericin in the silk, drying in a baking oven at 40 ℃ for 10min, dissolving in 0.85g of calcium chloride, 10mL of ethanol and 20mL of deionized water, uniformly stirring, dialyzing, filtering and freeze-drying to obtain silk fibroin, and dissolving the silk fibroin in formic acid with the mass fraction of 98% to obtain silk fibroin solution;
A2. adding 0.8g of modified calcium carbonate into 10mL of formic acid, carrying out ultrasonic treatment for 10min, adding 13g of silk fibroin solution, stirring for 3h to obtain a mixed solution, placing the mixed solution into an ejector, and collecting electrospinning by an electrospinning process to obtain the composite fiber, namely the anticracking agent, wherein the electrospinning voltage is 26KV, and the flow rate of the mixed solution is 2.4mL/min.
Comparative example 2
This comparative example differs from example 2 in that the modified calcium carbonate was replaced with the material prepared in comparative example 1.
Adding 0.8g of calcium carbonate into 10mL of formic acid, carrying out ultrasonic treatment for 10min, adding 13g of silk fibroin solution, stirring for 3h to obtain a mixed solution, placing the mixed solution into an ejector, and collecting electrospinning through an electrospinning process to obtain the anticracking agent, wherein the electrospinning voltage is 26KV, and the flow rate of the mixed solution is 2.4mL/min.
Comparative example 3
This comparative example differs from example 2 in that no modified calcium carbonate was added.
And placing the silk fibroin solution into an ejector, and collecting electrospinning by an electrospinning process to obtain the anti-cracking agent, wherein the electrospinning voltage is 26KV, and the flow rate of the mixed solution is 2.4mL/min.
Example 3, crack resistance aid was prepared by the following steps:
B1. mixing 15mL of saturated calcium hydroxide solution with 30mL of deionized water, stirring for 3min, adding 1.5g of metakaolin containing coal, stirring for 30min, soaking for 24h at 30 ℃, filtering, washing with deionized water for 3 times, drying in a 70 ℃ oven for 15min, taking out, grinding in a grinder to obtain powder, wherein the particle size of the powder is 2-3 mu m, adding 0.2g of graphene oxide into 50mL of deionized water, performing ultrasonic treatment for 5min to ensure that the graphene oxide is fully dispersed, adding 0.15g of powder, stirring for 2min at 4000rpm, soaking for 5min, filtering, washing with deionized water for 2 times, and drying in a 70 ℃ oven for 20min to obtain modified graphene oxide;
B2. adding 0.8g of modified graphene oxide and 0.6 silicon micropowder into 50mL of deionized water, carrying out ultrasonic treatment for 30min, adding 0.2mL of ethylene glycol and 1mL of ethanol, stirring for 30 mm, heating to 200 ℃, stirring for 30min, cooling to room temperature, filtering to obtain a gel substance, treating the gel substance at 800 ℃ for 2h under nitrogen atmosphere, and cooling to room temperature to obtain an anti-cracking auxiliary agent, wherein the particle size of the anti-cracking auxiliary agent is 20 mu m, and the pore diameter is 60nm; the particle diameter of the silicon micropowder is 30nm, and the specific surface area is 0.02m 2 /kg。
Comparative example 4
This comparative example differs from example 2 in that the coal-bearing metakaolin was not cationically modified, and the rest of the procedure and the feedstock were synchronized with example 2.
Comparative example 5
This comparative example differs from example 3 in that no silica fume was added and the rest of the procedure and raw materials were synchronized with example 2.
Example 4, method for preparing anti-crack concrete for fabricated building, comprising the following steps:
s1, preparing 309g of PO52.5 silicate cement, 601g of sand, 732g of stone, 93g of slag powder, 122g of cracking resistance agent and 20g of cracking resistance auxiliary agent, wherein the stone is prepared by mixing continuous graded broken stone of 5-10mm, broken stone of 5-20mm and broken stone of 5-31.5mm according to a mass ratio of 0.5:1:1.7;
s2, mixing and stirring the raw materials for 3min, adding 6g of PCE-102 polycarboxylate superplasticizer and 96g of water, and continuously stirring for 10min to obtain the anti-cracking concrete.
Example 5, method for preparing crack-resistant concrete for fabricated building, comprising the following steps:
s1, preparing 349g of PO52.5 silicate cement, 681g of sand, 812g of stones, 113g of slag powder, 132g of cracking resistance agent and 26g of cracking resistance auxiliary agent; the cobble is prepared by mixing crushed stone with continuous grading of 5-10mm, crushed stone with 5-20mm and crushed stone with 5-31.5mm according to the mass ratio of 1:1.5:1.8.
S2, mixing and stirring the raw materials for 3min, adding 9g of PCE-102 polycarboxylate superplasticizer and 106g of water, and continuously stirring for 10min to obtain the anti-cracking concrete.
Example 6, method for preparing crack-resistant concrete for fabricated building, comprising the following steps:
s1, preparing 399g of PO52.5 silicate cement, 720g of sand, 862g of stone, 163g of slag powder, 142g of cracking resistance agent and 30g of cracking resistance auxiliary agent; the cobble is prepared by mixing crushed stone with continuous grading of 5-10mm, crushed stone with 5-20mm and crushed stone with 5-31.5mm according to the mass ratio of 1.5:2:1.9.
S2, mixing and stirring the raw materials for 3min, adding 11g of PCE-101 polycarboxylate superplasticizer and 120g of water, and continuously stirring for 10min to obtain the anti-cracking concrete.
Comparative example 6
This comparative example differs from example 5 in that the anticracking agent was replaced with the material prepared in comparative example 2.
Comparative example 7
This comparative example differs from example 5 in that the anticracking agent was replaced with the material prepared in comparative example 3.
Comparative example 8
This comparative example differs from example 5 in that the cracking resistance aid was replaced with the material prepared in comparative example 4.
Comparative example 9
This comparative example differs from example 5 in that the cracking resistance aid was replaced with the material prepared in comparative example 5.
The anti-crack concrete prepared in examples 4 to 6 and comparative examples 6 to 9 was now subjected to performance test;
placing the prepared anti-cracking concrete on a test frame of a boiling box, and observing the appearance quality of the prepared anti-cracking concrete after boiling, so as to judge the influence of free calcium oxide on the concrete by the phenomena of cracking, loosening, collapsing and the like;
pouring the prepared concrete into concrete blocks, and detecting the compressive strength and the bending strength of the concrete by using a pressure detector, wherein the compressive strength and the bending strength are used for representing the cracking resistance of the concrete blocks;
directly measuring the thermal conductivity of the concrete by using a thermal flow meter method, measuring the thermal flow and the temperature difference of the prepared concrete by using a thermal flow coefficient tester, and calculating the thermal conductivity of the concrete;
the mechanical property of the concrete prepared above is detected according to the DL/T5332-2005 standard; the test results are shown in table 1 below:
TABLE 2
。
As can be seen from the data in table 2, in comparative example 6, the composite fiber prepared from calcium carbonate without surface modification of stearic acid was added into concrete, and the concrete was cracked, loosened and collapsed, and the crack resistance was reduced, probably because calcium carbonate without surface modification of stearic acid, the formed calcium stearate could form a waterproof layer along capillary holes, the contact angle between the wall of the hole and the water drops was increased, the water passing through the capillary holes could be reduced, and the crack formation by the expansion reaction with free calcium oxide was avoided; comparative example 7 the reinforcing material prepared from the non-added modified calcium carbonate was added to concrete, and its crack resistance was lowered, probably because the modified calcium carbonate had a strong mechanical property, and was able to enhance the mechanical strength of silk fibroin fibers, and contained a hydrophobic layer on the fiber surface, and was able to reduce the decomposition of composite fibers in alkaline concrete; comparative example 8 the prepared crack resistance additive was added to the concrete without cationic modification of the coal-containing metakaolin, and the concrete heat preservation and compressive strength were reduced, probably because the coal-containing metakaolin promoted the cement hydration reaction by cationic modification, and the nucleation effect of the graphene oxide aerogel was enhanced, and the compressive strength of the concrete was improved; comparative example 9 the silica fume was not added to the aerogel prepared from graphene oxide, and the prepared crack resistance aid was added to the concrete, and its compressive strength and fracture toughness were reduced, probably because the silica fume was used as a skeleton in the aerogel to avoid the graphene oxide being fragile after high temperature treatment, to improve the strength and durability of the aerogel, and to release silica fume to participate in the hydration reaction of free calcium oxide, to reduce the content of free calcium oxide in the cured concrete, and to improve the crack resistance.
The data in Table 2 shows that the anti-cracking concrete prepared in examples 6-9 not only has better anti-cracking property, compressive strength and heat preservation performance, but also has reduced content of free calcium oxide after the concrete is cured, and cannot influence the concrete. The preparation method comprises the steps of coating calcium carbonate with stearic acid, mixing the calcium carbonate with a silk fibroin solution, spinning to obtain composite fibers, namely an anti-cracking agent, mixing modified graphene oxide with silicon micropowder to prepare aerogel, obtaining an anti-cracking auxiliary agent, mixing Portland cement, sand, stones, slag powder, the anti-cracking agent and the anti-cracking auxiliary agent, adding a polycarboxylate water reducer and water, stirring and mixing to prepare anti-cracking concrete, wherein the anti-cracking concrete prepared in comparative example 8-11 does not meet the requirement of performance, and the anti-cracking concrete prepared in the invention has good anti-cracking performance, compression strength and heat preservation performance, and the content of free calcium oxide is reduced after the concrete is cured, so that the concrete is not influenced.
In the description of the present specification, the descriptions of the terms "one embodiment," "example," "specific example," and the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing is merely illustrative and explanatory of the invention, as various modifications and additions may be made to the particular embodiments described, or in a similar manner, by those skilled in the art, without departing from the scope of the invention or exceeding the scope of the invention as defined in the claims.
Claims (10)
1. The preparation method of the anti-cracking concrete for the assembled building is characterized by comprising the following steps of:
s1, coating calcium carbonate by adopting stearic acid to obtain modified calcium carbonate;
s2, doping modified calcium carbonate into a silk fibroin solution, and carrying out electrostatic spinning to obtain composite fibers, namely an anticracking agent;
s3, utilizing the cationic modified coal-containing metakaolin, adsorbing the cationic modified coal-containing metakaolin onto graphene oxide sheets to obtain modified graphene oxide, and mixing the modified graphene oxide with silicon micropowder to prepare aerogel to obtain an anti-cracking auxiliary agent;
s4, mixing the Portland cement, sand, stones, slag powder, an anti-cracking agent and an anti-cracking auxiliary agent, adding the polycarboxylate superplasticizer and deionized water, and stirring and mixing to obtain the anti-cracking concrete.
2. The method for preparing anti-crack concrete for fabricated building according to claim 1, wherein the anti-crack agent is prepared by the following steps:
A1. adding calcium carbonate into deionized water, placing in a water bath at 30 ℃ for ultrasonic treatment for 3min to obtain a dispersion liquid, adding stearic acid into the deionized water, uniformly stirring, placing in the dispersion liquid, carrying out ultrasonic treatment for 3min, placing in a baking oven at 105 ℃ for drying overnight, and grinding into fine powder by adopting a mortar and a pestle to obtain modified calcium carbonate;
A2. adding modified calcium carbonate into formic acid, carrying out ultrasonic treatment, adding a silk fibroin solution, stirring for 3 hours to obtain a mixed solution, placing the mixed solution into an ejector, carrying out electrostatic spinning under the condition that the electrostatic spinning voltage is 26KV and the flow rate of the mixed solution is 2.4mL/min, and collecting the electrostatic spinning to obtain the composite fiber, namely the anti-cracking agent.
3. The method for preparing the anti-cracking concrete for the fabricated building according to claim 2, wherein the particle size of the calcium carbonate is 0.1-0.5 μm, and the calcium content is more than or equal to 65%.
4. The method for preparing the anti-crack concrete for the fabricated building according to claim 2, wherein the length of the composite fiber is 5-10mm, and the diameter is 0.2-0.3mm.
5. The method for preparing anti-crack concrete for fabricated building according to claim 2, wherein the silk fibroin solution is prepared by the following steps: adding silk into a sodium carbonate solution, stirring for 1h at 100 ℃, taking out, washing with deionized water for 5 times, drying in a baking oven at 40 ℃ for 10min, dissolving in calcium chloride, ethanol and deionized water, stirring uniformly, dialyzing, filtering and freeze-drying to obtain silk fibroin, and dissolving the silk fibroin in formic acid with the mass fraction of 98% to obtain a silk fibroin solution.
6. The method for preparing the anti-cracking concrete for the fabricated building according to claim 1, wherein the anti-cracking additive is prepared by the following steps:
B1. mixing saturated calcium hydroxide solution with deionized water, stirring for 3min, adding coal-containing metakaolin, stirring for 30min, soaking at 30deg.C for 24h, filtering, washing, drying, taking out, grinding in a grinder to obtain powder with particle size of 2-3 μm, adding graphene oxide into deionized water, performing ultrasonic treatment for 5min, adding powder, stirring for 2min at 4000rpm, soaking for 5min, filtering, washing, and drying to obtain modified graphene oxide;
B2. adding modified graphene oxide and silicon micropowder into deionized water, performing ultrasonic treatment for 30min, adding ethylene glycol and ethanol, stirring for 30 mm, heating to 200 ℃, stirring for 30min, cooling to room temperature, filtering to obtain a gel-like substance, treating the gel-like substance for 2h at 800 ℃ under nitrogen atmosphere, and cooling to room temperature to obtain the anti-cracking auxiliary agent.
7. The method for preparing the fabricated building anti-cracking concrete according to claim 6, wherein the particle size of the anti-cracking additive is 10-30 μm, and the pore diameter is 50-100nm.
8. The method for preparing anti-cracking concrete for fabricated building according to claim 6, wherein the particle size of the silica powder is 10-40nm, and the specific surface area is 0.02m 2 /kg。
9. The method for preparing the anti-cracking concrete for the fabricated building according to claim 1, wherein the cobble is formed by mixing 5-10mm gravels, 5-20mm gravels and 5-31.5mm gravels with the mass ratio of (0.5-1.5): (1-2): (1.7-1.9).
10. An anti-crack concrete for fabricated building manufactured by the manufacturing method according to any one of claims 1 to 9.
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| CN105256544A (en) * | 2015-10-28 | 2016-01-20 | 南通纺织丝绸产业技术研究院 | High-performance natural silk fiber and preparation method thereof |
| AU2020100670A4 (en) * | 2019-04-30 | 2020-06-04 | Tongji University | Welding construction method suitable for cement-based material of combined concrete structure |
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