AU2017100110A4 - Nanosized core-shell structured organic-inorganic composite concrete-protecting agent and preparation method and use thereof - Google Patents
Nanosized core-shell structured organic-inorganic composite concrete-protecting agent and preparation method and use thereof Download PDFInfo
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- 239000003223 protective agent Substances 0.000 title claims abstract description 66
- 239000011258 core-shell material Substances 0.000 title claims abstract description 39
- 239000002131 composite material Substances 0.000 title claims abstract description 36
- 238000002360 preparation method Methods 0.000 title abstract description 10
- 239000004567 concrete Substances 0.000 claims abstract description 70
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical group [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 claims abstract description 29
- 230000002209 hydrophobic effect Effects 0.000 claims abstract description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 36
- 229910000077 silane Inorganic materials 0.000 claims description 27
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 19
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 18
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 15
- 238000003756 stirring Methods 0.000 claims description 15
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical group C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 14
- 125000001165 hydrophobic group Chemical group 0.000 claims description 14
- 239000008367 deionised water Substances 0.000 claims description 12
- 229910021641 deionized water Inorganic materials 0.000 claims description 12
- 239000003495 polar organic solvent Substances 0.000 claims description 12
- 239000002344 surface layer Substances 0.000 claims description 12
- 239000003513 alkali Substances 0.000 claims description 8
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 7
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 6
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 claims description 6
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 6
- 238000005507 spraying Methods 0.000 claims description 6
- FWDBOZPQNFPOLF-UHFFFAOYSA-N ethenyl(triethoxy)silane Chemical compound CCO[Si](OCC)(OCC)C=C FWDBOZPQNFPOLF-UHFFFAOYSA-N 0.000 claims description 5
- 239000007788 liquid Substances 0.000 claims description 5
- 229920001843 polymethylhydrosiloxane Polymers 0.000 claims description 5
- 239000007787 solid Substances 0.000 claims description 5
- 239000003960 organic solvent Substances 0.000 claims description 4
- 239000007921 spray Substances 0.000 claims description 3
- 239000011148 porous material Substances 0.000 abstract description 31
- 239000004568 cement Substances 0.000 abstract description 28
- 239000000463 material Substances 0.000 abstract description 20
- 230000000694 effects Effects 0.000 abstract description 8
- 239000002243 precursor Substances 0.000 abstract description 8
- 238000010276 construction Methods 0.000 abstract description 5
- 238000006703 hydration reaction Methods 0.000 abstract description 5
- 230000007062 hydrolysis Effects 0.000 abstract description 5
- 238000006460 hydrolysis reaction Methods 0.000 abstract description 5
- 230000032683 aging Effects 0.000 abstract description 4
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 abstract description 4
- 239000000920 calcium hydroxide Substances 0.000 abstract description 4
- 229910001861 calcium hydroxide Inorganic materials 0.000 abstract description 4
- 235000011116 calcium hydroxide Nutrition 0.000 abstract description 4
- 239000004035 construction material Substances 0.000 abstract description 4
- 230000036571 hydration Effects 0.000 abstract description 4
- 125000002887 hydroxy group Chemical group [H]O* 0.000 abstract description 2
- 229910010272 inorganic material Inorganic materials 0.000 abstract description 2
- 239000011147 inorganic material Substances 0.000 abstract description 2
- 239000011368 organic material Substances 0.000 abstract description 2
- 229910004298 SiO 2 Inorganic materials 0.000 abstract 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract 1
- 125000001931 aliphatic group Chemical group 0.000 abstract 1
- 229910052799 carbon Inorganic materials 0.000 abstract 1
- 230000001681 protective effect Effects 0.000 abstract 1
- 238000006243 chemical reaction Methods 0.000 description 17
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 16
- 229910052681 coesite Inorganic materials 0.000 description 14
- 229910052906 cristobalite Inorganic materials 0.000 description 14
- 229910052682 stishovite Inorganic materials 0.000 description 14
- 229910052905 tridymite Inorganic materials 0.000 description 14
- 239000010410 layer Substances 0.000 description 13
- 239000000243 solution Substances 0.000 description 10
- 230000008569 process Effects 0.000 description 8
- 239000002585 base Substances 0.000 description 7
- 150000002500 ions Chemical class 0.000 description 7
- 239000011083 cement mortar Substances 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- 230000007246 mechanism Effects 0.000 description 5
- 238000011282 treatment Methods 0.000 description 5
- 238000010521 absorption reaction Methods 0.000 description 4
- 230000006872 improvement Effects 0.000 description 4
- 230000035515 penetration Effects 0.000 description 4
- 239000010409 thin film Substances 0.000 description 4
- ALVYUZIFSCKIFP-UHFFFAOYSA-N triethoxy(2-methylpropyl)silane Chemical compound CCO[Si](CC(C)C)(OCC)OCC ALVYUZIFSCKIFP-UHFFFAOYSA-N 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 239000002105 nanoparticle Substances 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 239000006228 supernatant Substances 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000010408 film Substances 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 230000001965 increasing effect Effects 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- XDLMVUHYZWKMMD-UHFFFAOYSA-N 3-trimethoxysilylpropyl 2-methylprop-2-enoate Chemical compound CO[Si](OC)(OC)CCCOC(=O)C(C)=C XDLMVUHYZWKMMD-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 229910001413 alkali metal ion Inorganic materials 0.000 description 1
- 229910052910 alkali metal silicate Inorganic materials 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 230000009545 invasion Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 150000004756 silanes Chemical class 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/60—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only artificial stone
- C04B41/61—Coating or impregnation
- C04B41/65—Coating or impregnation with inorganic materials
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/46—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with organic materials
- C04B41/49—Compounds having one or more carbon-to-metal or carbon-to-silicon linkages ; Organo-clay compounds; Organo-silicates, i.e. ortho- or polysilicic acid esters ; Organo-phosphorus compounds; Organo-inorganic complexes
- C04B41/4905—Compounds having one or more carbon-to-metal or carbon-to-silicon linkages ; Organo-clay compounds; Organo-silicates, i.e. ortho- or polysilicic acid esters ; Organo-phosphorus compounds; Organo-inorganic complexes containing silicon
- C04B41/4922—Compounds having one or more carbon-to-metal or carbon-to-silicon linkages ; Organo-clay compounds; Organo-silicates, i.e. ortho- or polysilicic acid esters ; Organo-phosphorus compounds; Organo-inorganic complexes containing silicon applied to the substrate as monomers, i.e. as organosilanes RnSiX4-n, e.g. alkyltrialkoxysilane, dialkyldialkoxysilane
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/46—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with organic materials
- C04B41/49—Compounds having one or more carbon-to-metal or carbon-to-silicon linkages ; Organo-clay compounds; Organo-silicates, i.e. ortho- or polysilicic acid esters ; Organo-phosphorus compounds; Organo-inorganic complexes
- C04B41/4905—Compounds having one or more carbon-to-metal or carbon-to-silicon linkages ; Organo-clay compounds; Organo-silicates, i.e. ortho- or polysilicic acid esters ; Organo-phosphorus compounds; Organo-inorganic complexes containing silicon
- C04B41/495—Compounds having one or more carbon-to-metal or carbon-to-silicon linkages ; Organo-clay compounds; Organo-silicates, i.e. ortho- or polysilicic acid esters ; Organo-phosphorus compounds; Organo-inorganic complexes containing silicon applied to the substrate as oligomers or polymers
- C04B41/4961—Polyorganosiloxanes, i.e. polymers with a Si-O-Si-O-chain; "silicones"
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
- C04B41/5025—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials with ceramic materials
- C04B41/5035—Silica
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Aftertreatments Of Artificial And Natural Stones (AREA)
Abstract
Embodiments of the present invention disclose a nanosized core-shell structured organic-inorganic composite concrete-protecting agent, as well as its preparation method and use, which belong to the technical field of construction materials. The present invention allows silane groups to wrap the surface of nano-SiO 2 to form a core-shell structure, so as to effectively combine organic and inorganic protecting agents and provide protection for surface-hardened concrete. The present invention avoids the problem of easy ageing of the organic components, separates the preparation and application of materials, saves time for hydrolysis of precursors, and provides double protection for concrete structures. The present invention has the advantages of both organic and inorganic materials. On one hand, silane forms a protective film on the surface of concrete to exert a hydrophobic effect. On the other hand, nano-SiO 2 has high pozzolanic activity and undergoes hydration reaction with the hydration product of cement Ca(OH)2 to form a hydrated gel which densifies the pore structures. The protecting agent is characterized by offering a good protection effect, being easy to prepare, and being convenient for construction application, and can be widely applied in the field of concrete-based constructions. (Figure 1) hydroxy hydrophobic (4<aliphatic structure of carbon fondcloon]l grooip -e-, Protecing Agenn of Example 1 -.-lan control. I fn
Description
NANOSIZED CORE-SHELL STRUCTURED ORGANIC-INORGANIC COMPOSITE CONCRETE-PROTECTING AGENT AND PREPARATION METHOD AND USE THEREOF
TECHNICAL FIELD
[0001] Embodiments of the present invention relate to the field of construction materials, and in particular to a nanosized core-shell structured organic-inorganic composite concrete-protecting agent as well as its preparation method and use.
BACKGROUND
[0002] Ferroconcrete, as the most extensively used artificial construction material over the world nowadays, is widely applied in various fields of constructions such as buildings, public facilities, and bridges. Quality and life of buildings directly depend on the quality and life of concrete, and thus durability of the concrete structures has a significant impact on economy, society, resources, energy sources and the like in China. Deterioration in performance of cement concrete due to the action of force and environmental factors during its use is the major factor shortening the service life of the material. Deterioration in performance of concrete incurs economic losses as enormous as thousands of billions per year worldwide, and China is currently undergoing a period of massive economic construction. Therefore, improvement in the ability of concrete to resist external corrosion so as to extend its service life would have great economic significance and also answer the call for sustainable development in China. The deterioration of concrete caused by its service environment is a process taking effect form the surface towards the inside, and the quality of the surface layer of concrete directly impacts on the overall anti-deterioration ability of the structure. Improvement in the performance of the entire structure by improvement in quality of the surface layer of concrete has long been drawing research attention, and a common technical means is to use an external protective layer to improve the quality of the surface layer of concrete.
[0003] Generally speaking, concrete-protecting layers are mainly categorized into organic protecting layers and inorganic protecting layers. Organic protecting layers prevent unwanted ions carried by media, mainly water and gas, from penetrating into the inside of concrete, mainly by formation of a continuous thin film on the surface of concrete. According to the mechanism of surface protection, organic protecting layers are further divided into silane-based protecting agents and film-forming emulsion protecting agents, of which the former impedes water penetration into pores mainly by formation of a thin film in the pores on the surface layer of concrete to alter hydrophilicity of pores without affecting gas exchange between the inside and outside of concrete, and the latter blocks all substance exchange between concrete and the environment by formation of a continuous thin film covering the surface of concrete. The major problem of such protecting agents lies in the poor weather resistance of organic components. Inorganic protecting layers are sealing layers formed of inorganic materials on the surface of concrete, such as a crystalline protecting layer, and their main functional component is alkali metal silicate. Although inorganic protecting layers can effectively seal a concrete structure, the alkali metal ions produced from reaction are apparently unfavorable to alkali-aggregate reaction of concrete and metal salt crystal precipitation.
[0004] Regarding the surface-protecting material for concrete in the prior art, for example, the patent application CN 201310221449.6 titled "Concrete protecting agent based on in situ reaction" discloses a method for protecting the hardened surface of concrete by utilizing colloidal sol nano-Si02 or a precursor thereof, highlighting that the nano-Si02 or a precursor thereof reacts with a cement base material to produce a C-S-H gel which improves the pore structure of concrete material and reduces porosity. In another example, the patent application CN 201310019374.3 titled "Organo-silicon concrete-protecting agent and preparation method thereof' discloses an organo-silicon concrete-protecting agent and a preparation method thereof, which mainly relates to formation of a hydrophobic film lining the inner wall of pores of concrete by coating a paste made from silane as the major raw material on the concrete surface to prevent entry of unwanted ions carried by water.
[0005] Although the above two methods can protect a concrete structure to an extent, they have disadvantages. Organic concrete-protecting agents are disadvantageous in that they have a weak bonding force with the cement base material and poor wear resistance and durability, require regular coating operations, and have organic components that can easily age. The inorganic protecting agent based on in situ reaction can effectively improve the pore structure of concrete, but requires a long time to slowly produce nano-Si02 by hydrolysis, because it relies on the reaction between the water in the pore structure of concrete and a precursor of the nano-Si02.
[0006] Giovana Collodetti et at., 2014 in Construction and Building Materials, Vol. 54, pages 99-105 studies a new material formed by two different kinds of silane compounds grafted onto the surface of Si02 nanoparticles, and the effect of this material, after blended into cement, on hydration of a cement slurry. The results demonstrate that this material is unfavorable for cement performance improvement, and thus negate the use of the internal blending method.
SUMMARY
[0007] In order to address the above issues in the prior art, embodiments of the present invention are directed to a nanosized core-shell structured organic-inorganic composite concrete-protecting agent, as well as its preparation method, in which tetraethyl orthosilicate, a silane, and deionized water are dissolved in a polar organic solvent in a certain ratio and allowed to react sufficiently, such that the hydrophobic groups of the silane are grafted onto the surface of nano-SiCh, so as to effectively combine organic and inorganic protecting agents and form a core-shell structured material, which is used to provide protection for surface-hardened concrete by the reaction of nano-SiC>2 with the cement portion to produce a C-S-H gel that functions to block the pores. The concrete-protecting agent avoids the problem of easy ageing of the organic components, separates the preparation and application of material, saves time for hydrolysis of precursors, and provides double protection for a concrete structure.
[0008] The technical solution of an embodiment of the present invention relates to a nanosized core-shell structured organic-inorganic composite concrete-protecting agent consisting of the following components in weight percentage: 0.5% to 1.4% of silane having a hydrophobic group, 4.1% to 8% of tetraethyl orthosilicate, 89% to 94.8% of a polar organic solvent, 0.1% of alkali, and 0.5% to 1.5% of water.
[0009] In a further embodiment, the nanosized core-shell structured organic-inorganic composite concrete-protecting agent preferably consisting of the following components in weight percentage: 0.5% of silane having a hydrophobic group, 6% of tetraethyl orthosilicate, 92.9% of a polar organic solvent, 0.1% of alkali, and 0.5% of water.
[0010] The silane having a hydrophobic group is preferably a polymethylhydrosiloxane, a vinyltriethoxysilane, or an isobutyltriethoxysilane.
[0011] The polar organic solvent is preferably tetrahydrofuran, ethanol or methanol.
[0012] The alkali is preferably aqueous ammonia or ethylenediamine, and the aqueous ammonia preferably has a mass concentration of 0.88 g/ml.
[0013] The water is preferably deionized water.
[0014] The nanosized core-shell structured organic-inorganic composite concrete-protecting agent may be prepared by the method comprising the steps of: according to the defined ratio, preparing a volume of the polar organic solvent, adjusting the pH of the polar organic solvent to 8-12 by addition of the alkali, then adding silane having a hydrophobic group thereto followed by stirring for 30 min, then adding tetraethyl orthosilicate, followed by further stirring for 10 to 12 h, adding deionized water, followed by stirring for 2 to 3.5 hours until the solution turns from transparency to turbidity, centrifuging the solution at 10,000 rpm for 5 min, and collecting the precipitated solid to obtain the nanosized core-shell structured organic-inorganic composite concrete-protecting agent.
[0015] The nanosized core-shell structured organic-inorganic composite concrete-protecting agent may be used as a protecting agent for surface-hardened concrete, and used in the manner that the nanosized core-shell structured organic-inorganic composite concrete-protecting agent is ultra-sonically dispersed in an organic solvent at a mass concentration of 5% to obtain a mixed liquid, which is then spray-coated onto the surface of concrete, the spray-coating is repeated for 3 times at an interval of 20 min, and for each spray-coating the amount of the mixed liquid used is 2.5 to 3.5 L/m2 until the surface layer of concrete is sufficiently wetted.
[0016] The organic solvent is preferably tetrahydrofuran, ethanol or methanol.
[0017] The present invention aims to treat the surface layer of hardened concrete with a new material formed by silane grafted onto the surface of nano-Si02, such that an organic protecting layer and an inorganic protecting layer are effectively combined, based on the concept that improved surface quality of cement concrete has an important effect on the overall structure. On one hand, the organic part forms a thin film in the pores in the surface layer of concrete to alter the hydrophilicity of the pores and impede penetration of water into the pores, without affecting gas exchange between the inside and outside of the concrete. On the other hand, the hydrated gel formed by the pozzolanic reaction between the surface concrete and the hydration product of cement Ca(OH)2 densifies the concrete structure by effectively sealing microcracks in the concrete and improves the overall quality of the concrete. Such a method effectively integrates an organic protecting layer and an inorganic protecting layer, not only enhancing the bonding ability of silane to a cement base material, but also increasing the dense degree of the porous structure of concrete, so as to provide double protection for concrete. The present invention combines the advantages of an organic protecting agent and an inorganic protecting agent, also overcomes the drawbacks of poor adherence and proneness to ageing of organic protecting agents and the drawback of long reaction duration of inorganic protecting agents, is convenient to prepare at a low synthesis temperature, and exhibits a significant waterproof effect.
[0018] The present invention effectively combines an organic protecting agent and an inorganic protecting agent in that the hydrophobic groups at one end of the silane molecules form a protecting film on the concrete surface which effectively blocks penetration of water and prevents unwanted ions from invading the porous structure of concrete via the water medium, and the other end of the silane molecules are bonded to nano-Si02 which further reacts with the cement base material, such that the silane is firmly immobilized on the concrete surface and the pores are also blocked. As a result, durability of the silane material on the concrete surface is greatly improved, while the porous structure of the concrete is also improved. The double action impedes penetration of water, and blocks unwanted ions.
[0019] Principle of the present invention [0020] The silane used is those having a hydrophobic group, such as a polymethylhydrosiloxane, a vinyltriethoxysilane, or an isobutyltriethoxysilane. Nano-SiCE is prepared generally from tetraethyl orthosilicate (TEOS) as a precursor. Tetraethyl orthosilicate as a silicon source for preparation of nano-SiC>2 undergoes a chemical reaction such as hydrolysis under certain conditions to produce nanoparticles, while the organic alcohol produced from the hydrolysis is highly volatile. The mechanism by which tetraethyl orthosilicate densifies the concrete structure lies in that it enters the pore structure and is hydrolyzed by the water available within the pores to produce silica that can participate in the pozzolanic reaction and ethanol harmless to the cement base material.
[0021]
Eq. (1) [0022] At this stage the silane having a hydrophobic group will react with the nano-SiC>2 having many hydroxyl groups on its surface (the reaction mechanism is shown in Figure 1).
[0023] Even though surrounded by the hydrophobic groups of the silane, nano-Si02 still has high pozzolanic activity and rapidly absorbs Ca(OH)2 produced from cement hydration in concrete to produce a hydrated gel. This process is fundamental for the application in cement concrete and follows the reaction mechanism of Eq. (2) below: [0024]
Eq. (2) [0025] Tetraethyl orthosilicate as the precursor of Nano-Si02, silane, and deionized water in a certain ratio are dissolved in a polar organic solvent and well mixed, and are allowed to react sufficiently such that the hydrophobic groups of the silane are grafted onto the surface of nano-Si02. The synthesized material is used to treat the surface of a concrete article to allow the nano-Si02 to react with the cement portion to produce a C-S-H gel, such that the pores are blocked and meanwhile the hydrophobic effect of the silane prevents unwanted ions carried by water from invading the inside of concrete and damaging the concrete structure.
[0026] By the above technical solution, the present invention has the following characteristics: [0027] 1) The combination of organic and inorganic components not only produces a significant hydrophobic effect on the surface, but also allows reaction with the cement base deep in the concrete structure to block pores, thereby offering the concrete base material double protection, which is better than using silane or naon-Si02 alone.
[0028] 2) The organic and inorganic components are bound together by a core-shell structure, which effectively overcomes the problem of easy ageing of organic materials and extends the service life of the material.
[0029] 3) The protecting agent per se has high pozzolanic activity which allows the protecting agent to react with the calcium hydroxide in the surface layer of concrete, and the products of pozzolanic reaction effectively densifies the surface layer of the concrete structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Fig. 1 is a schematic representation of the mechanism according to the present invention by which S1O2 nanoparticles bind silane; [0031] Fig. 2 is a graph showing the water absorption of cement mortar samples subjected to different treatments in Example 4; [0032] Fig. 3 shows contact angles on the surface of cement pastes coated with different protecting materials in Example 5: (a) the contact angle upon treatment with the nanosized core-shell structured organic-inorganic composite concrete-protecting agent; and (b) the contact angle when no treatment was made; [0033] Fig. 4 shows the pore distribution of the cements in Example 6.
DETAILED DESCRIPTION
[0034] The present invention will be further described in conjunction with Examples below.
[0035] Example 1 [0036] A nanosized core-shell structured organic-inorganic composite concrete-protecting agent having the following components in weight percentage: 0.5% of polymethylhydrosiloxane, 6% of tetraethyl orthosilicate, 92.9% of tetrahydrofuran, 0.1% of ethylenediamine, and 0.5% of deionized water.
[0037] The concrete-protecting agent was prepared by the following process: tetrahydrofuran was weighed according to the defined ratio, ethylenediamine was added to adjust the pH to 8-12, then polymethylhydrosiloxane was added, followed by stirring for 30 min with a magnetic stirrer, then tetraethyl orthosilicate was added, followed by further stirring for 11 h, then deionized water was added, followed by stirring for 3 hours until the solution turned from transparency to turbidity, indicating completion of reaction; the solution was centrifuged at 10,000 rpm for 5 min in a high-speed centrifuge, the supernatant was removed by filtration, and the solid at the bottom of the centrifuge tube was collected to obtain the nanosized core-shell structured organic-inorganic composite concrete-protecting agent of this example.
[0038] Example 2 [0039] A nanosized core-shell structured organic-inorganic composite concrete-protecting agent having the following components in weight percentage: 1.4% of a vinyltriethoxysilane, 8% of tetraethyl orthosilicate, 89% of ethanol, 0.1% of ethylenediamine, and 1.5% of deionized water.
[0040] The concrete-protecting agent was prepared by the following process: ethanol was weighed according to the defined ratio, ethylenediamine was added to adjust the pH to 8-11, then vinyltriethoxysilane was added, followed by stirring for 30 min with a magnetic stirrer, then tetraethyl orthosilicate was added, followed by further stirring for 10 h, then deionized water was added, followed by stirring for 2 hours until the solution turned from transparency to turbidity, indicating completion of reaction; the solution was centrifuged at 10,000 rpm for 5 min in a high-speed centrifuge, the supernatant was removed by filtration, and the solid at the bottom of the centrifuge tube was collected to obtain the nanosized core-shell structured organic-inorganic composite concrete-protecting agent of this example.
[0041] Example 3 [0042] A nanosized core-shell structured organic-inorganic composite concrete-protecting agent having the following components in weight percentage: 0.9% of an isobutyltriethoxysilane, 6% of tetraethyl orthosilicate, 92% of methanol, 0.1% of aqueous ammonia, and 1% of deionized water.
[0043] The concrete-protecting agent was prepared by the following process: methanol was weighed according to the defined ratio, aqueous ammonia was added to adjust the pH to 8-11, then isobutyltriethoxysilane was added, followed by stirring for 30 min with a magnetic stirrer, then tetraethyl orthosilicate was added, followed by further stirring for 12 h, then deionized water was added, followed by stirring for 3.5 hours until the solution turned from transparency to turbidity, indicating completion of reaction; the solution was centrifuged at 10,000 rpm for 5 min in a high-speed centrifuge, the supernatant was removed by filtration, and the solid at the bottom of the centrifuge tube was collected to obtain the nanosized core-shell structured organic-inorganic composite concrete-protecting agent of this example.
[0044] Use of experiment results [0045] Example 4 [0046] The nanosized core-shell structured organic-inorganic composite concrete-protecting agent prepared in Example 1 was used to treat a one-year old cement mortar sample having a water-cement ratio of 0.6, by the following process. The protecting agent of Example 1 was dissolved in tetrahydrofuran at a mass concentration of 5% to obtain a mixed liquid which was then spray-coated onto the surface of the cement mortar sample, wherein the spray-coating was repeated for 3 times at an interval of 20 min, and each spray-coating was performed until the surface layer of concrete was sufficiently wetted. After 3-day standard maintenance, the water absorption rate by the cement mortar sample was measured. Meanwhile the water absorption rates by cement mortar samples which were untreated, treated with silane, and treated with a Si02 precursor were also measured under the same condition. The results are shown in Fig. 2.
[0047] It can be seen from the curves in Fig. 2 that the cement mortar sample treated with the nanosized core-shell structured organic-inorganic composite concrete-protecting agent according to the present invention showed a significantly decreased water absorption rate, indicating that the protecting agent according to the present invention combines the advantages of both organic and inorganic protecting agents in that the silane having a hydrophobic group serves as a hydrophobic agent preventing immersion of a part of water, and the nano-SiCh acts to block the pores to reduce the porosity of concrete and reduce the amount of water migrating into the surface layer of concrete, such that the double action impedes invasion of water and blocks the impact of unwanted ions.
[0048] Example 5 [0049] The nanosized core-shell structured organic-inorganic composite concrete-protecting agent prepared in Example 2 was used to treat a cement paste sample having a water-cement ratio of 0.38, by the same treatment process as in Example 4. The contact angles of the sample and of an untreated blank control group were obtained and the results are shown in Fig. 3.
[0050] From the contact angle results shown in Fig. 3, it can be seen that the nanosized core-shell structured organic-inorganic composite concrete-protecting agent significantly changed the surface hydrophilicity of concrete, increased the contact angle, and prevented water carrying unwanted ions from easily invading the inner structure of concrete.
[0051] Example 6 [0052] The nanosized core-shell structured organic-inorganic composite concrete-protecting agent prepared in Example 1 was used to treat the surface of a cement paste sample having a water-cement ratio of 0.4, by the same treatment process as in Example 4. The pore structure of the sample was measured by the mercury injection method, and the obtained data are shown in Figure 4 in comparison with a blank control.
[0053] The blank control group showed a total porosity of 17.74%, while the cement treated with the nanosized core-shell structured organic-inorganic composite concrete-protecting agent according to the present invention showed a porosity of 18.20%. The two porosities have a small difference within the range of error. However, as can be seen in Fig.4, in the cement treated with the nanosized core-shell structured organic-inorganic composite concrete-protecting agent, harmful pores (50 nm to 200 nm) are significantly reduced, and moderately harmful pores (20 nm to 50 nm) have a peak pore size apparently shifted towards that of harmless pores. This indicates that in the cement treated with the nanosized core-shell structured organic-inorganic composite concrete-protecting agent, harmful pores have turned towards harmless pores, and large pores are significantly fewer than those in untreated samples. The results demonstrate that the protecting agent according to the present invention can function to block pores, and increase the dense degree of the pore structures of concrete. The detailed pore size distribution is shown in Table 1.
[0054] Table 1: Pore size distribution of treated cement
Claims (10)
- WHAT IS CLAIMED IS:1. A nanosized core-shell structured organic-inorganic composite concrete-protecting agent consisting of the following components in weight percentage: 0.5% to 1.4% of silane having a hydrophobic group, 4.1% to 8% of tetraethyl orthosilicate, 89% to 94.8% of a polar organic solvent, 0.1% of alkali, and 0.5% to 1.5% of water.
- 2. The nanosized core-shell structured organic-inorganic composite concrete-protecting agent according to claim 1, consisting of the following components in weight percentage: 0.5% of silane having a hydrophobic group, 6% of tetraethyl orthosilicate, 92.9% of a polar organic solvent, 0.1% of alkali, and 0.5% of water.
- 3. The nanosized core-shell structured organic-inorganic composite concrete-protecting agent according to claim 1, wherein the silane having a hydrophobic group is a polymethylhydrosiloxane, a vinyltriethoxysilane, or an i sobutyltriethoxysilane.
- 4. The nanosized core-shell structured organic-inorganic composite concrete-protecting agent according to claim 1, wherein the polar organic solvent is tetrahydrofuran, ethanol or methanol.
- 5. The nanosized core-shell structured organic-inorganic composite concrete-protecting agent according to claim 1, wherein the alkali is aqueous ammonia or ethylenediamine, and the aqueous ammonia has a mass concentration of 0.88 g/ml.
- 6. The nanosized core-shell structured organic-inorganic composite concrete-protecting agent according to claim 1, wherein the water is deionized water.
- 7. A method for preparing the nanosized core-shell structured organic-inorganic composite concrete-protecting agent according to any one of claims 1 to 6, comprising: according to a defined ratio, preparing a volume of the polar organic solvent, adjusting the pH of the polar organic solvent to 8-12 by addition of the alkali, then adding silane having a hydrophobic groupthereto followed by stirring for 30 min, then adding tetraethyl orthosilicate followed by further stirring for 10 to 12 h, adding deionized water followed by stirring for 2 to 3.5 hours until the solution turns from transparency to turbidity, then centrifuging the solution at 10,000 rpm for 5 min, and collecting the solid at the bottom to obtain the nanosized core-shell structured organic-inorganic composite concrete-protecting agent.
- 8. Use of the nanosized core-shell structured organic-inorganic composite concrete-protecting agent according to any one of claims 1 to 6 as a protecting agent for surface-hardened concrete.
- 9. The use according to claim 8, wherein the concrete-protecting agent is used in the manner that the nanosized core-shell structured organic-inorganic composite concrete-protecting agent is ultra-sonically dispersed in the organic solvent at a mass concentration of 5% to obtain a mixed liquid which is then spray-coated onto the surface of concrete, wherein the spray-coating is repeated for 3 times at an interval of 20 min, and for each spray-coating the amount of the mixed liquid used is 2.5 to 3.5 L/m2 until the surface layer of concrete is sufficiently wetted.
- 10. The use according to claim 8, wherein the organic solvent is tetrahydrofuran, ethanol or methanol.
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| CN201610066508.0 | 2016-02-01 | ||
| CN201610066508.0A CN105712740A (en) | 2016-02-01 | 2016-02-01 | Nano core-shell structure organic-inorganic compound concrete protective agent and preparation method and application thereof |
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| CN115304325A (en) * | 2022-07-28 | 2022-11-08 | 深圳市安托山混凝土有限公司 | Anti-cracking corrosion-resistant marine concrete |
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| CN109053224A (en) * | 2018-10-30 | 2018-12-21 | 青岛明象新材料技术有限公司 | A kind of graphene nano silicon metal waterproofing agent and preparation method thereof |
| CN110028312B (en) * | 2019-04-28 | 2022-04-05 | 国装新材料技术(江苏)有限公司 | High-temperature-resistant ceramic precursor slurry and preparation method thereof |
| CN110655417B (en) * | 2019-10-12 | 2020-10-20 | 山东大学 | Composite nano material protective agent and method for protecting concrete surface by using same |
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| CN111205767B (en) * | 2020-02-26 | 2022-02-01 | 科顺防水科技股份有限公司 | Super-hydrophobic coating for corrosion prevention and freeze-thaw resistance of concrete and preparation method thereof |
| CN111410556B (en) * | 2020-03-02 | 2022-04-05 | 戚城 | High-performance concrete surface protective agent and preparation method thereof |
| CN111410481B (en) * | 2020-03-31 | 2022-01-28 | 河海大学 | Core-shell nanoparticle modified cement-based protective material and preparation method thereof |
| CN111875320B (en) * | 2020-08-19 | 2021-11-05 | 济南大学 | Super-hydrophobic microcapsule polymer cement-based anticorrosive paint and preparation method and application thereof |
| CN112723914B (en) * | 2020-12-11 | 2022-03-04 | 四川砼道科技有限公司 | Concrete surface reinforcing agent and preparation method thereof |
| CN114261007A (en) * | 2021-12-20 | 2022-04-01 | 中建商品混凝土有限公司 | Concrete surface functional recombination material and use method thereof |
| CN115160841B (en) * | 2022-07-20 | 2023-09-22 | 高速铁路建造技术国家工程研究中心 | Concrete protective material and preparation and construction methods thereof |
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| CN102766241A (en) * | 2011-05-06 | 2012-11-07 | 北京化工大学 | Core-shell structured nano-silica/polyacrylate emulsion and its preparation method |
| CN102432336B (en) * | 2011-09-26 | 2013-02-20 | 浙江大学 | Preparation for organic/inorganic composite corrosion-resisting protective film coating layer for concrete and application thereof |
| CN103435366B (en) * | 2013-06-06 | 2015-12-09 | 济南大学 | A kind of reaction in－situ type concrete protectant |
| CN103553708B (en) * | 2013-10-03 | 2015-04-15 | 浙江大学 | Method for preparation of rapidly-solidified penetration-type protective agent for sea engineering concrete |
| CN105254332B (en) * | 2015-09-18 | 2017-09-29 | 重庆大学 | One kind carries out armored concrete method of inhibiting corrosion with nano silicon |
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| CN115304325A (en) * | 2022-07-28 | 2022-11-08 | 深圳市安托山混凝土有限公司 | Anti-cracking corrosion-resistant marine concrete |
| CN115304325B (en) * | 2022-07-28 | 2023-05-09 | 深圳市安托山混凝土有限公司 | Anti-cracking corrosion-resistant marine concrete |
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