Concrete carbonization inhibitor, preparation method and application

Abstract

The invention discloses a concrete carbonization inhibitor, a preparation method and application, and belongs to the technical field of building materials. The concrete carbonization inhibitor is prepared from the following raw materials: modified calcium oxide, alkylol amine, an organosilicon waterproofing agent, a polycarboxylic acid water reducing agent, a filler and a defoaming agent, wherein the modified calcium oxide is calcium oxide subjected to siloxane surface hydrophobic modification. According to the concrete carbonization inhibitor, concrete is compacted through the filling agent and the modified calcium oxide reaction product, the amount of permeating carbon dioxide is reduced, water transmitted into the concrete is reduced by doping the waterproof agent, and meanwhile carbon dioxide permeating into the concrete is consumed through chemical reaction. According to the concrete carbonization inhibitor, through the dense hydrophobic and chemical combination effect, the effect of improving the carbonization resistance of concrete is achieved; the admixture can improve the carbonization resistance and long-term stability of concrete and effectively reduce the carbonization depth of the concrete.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to a concrete carbonization inhibitor, a preparation method and an application thereof. Background Art

[0002] Concrete carbonization is one of the important durability indicators of concrete. After cement in concrete is hydrated, hydrogen-modified calcium oxide is generated, most of which exists in the concrete in a crystalline form. Concrete carbonization is the process of carbon dioxide in the air penetrating into the concrete and reacting with hydrogen-modified calcium oxide, causing the alkalinity of the concrete to decrease, leading to rusting of steel bars and volume expansion, which in turn leads to cracking and damage of the concrete structure.

[0003] Concrete materials will inevitably produce cracks during the construction process, and will also suffer from corrosion damage during service, causing cracking, peeling and other phenomena. Therefore, carbonization not only occurs on the surface of concrete, but the concrete as a whole should have anti-carbonization properties.

[0004] At present, the main prevention and control measures for the carbonation of concrete are as follows: (1) Reduce the water-cement ratio. The density of concrete can be improved by reducing the water-cement ratio, but this method depends on the construction conditions on site, and reducing the water-cement ratio will bring other problems, such as increased construction difficulty and increased costs; (2) Surface protection. Reduce carbon dioxide transmission. Patent application CN115627103A discloses a concrete anti-carbonation coating, which is composed of a sacrificial carbonization component A, a concrete inner surface intercalation barrier component B, a concrete inner layer microstructure regulation component C and a composite solution D as the main raw materials. It is directly applied to the concrete surface to prevent the carbonation of concrete. Patent application CN111925675A discloses a concrete anti-carbonization coating and its construction method, which includes 2 to 10 parts of silica sol, 20 to 80 parts of steel slag powder, 15 to 40 parts of water-based fluorine-containing acrylic polymer emulsion, 15 to 30 parts of heavy calcium carbonate powder, 0.5 to 3 parts of sepiolite powder, 0.1 to 0.5 parts of nano silicon carbide whiskers, 0.1 to 2.5 parts of water reducer, 2 to 8 parts of silica fume, 20 to 60 parts of cement and 25 to 80 parts of water. After the base surface to be constructed is pretreated, the prepared coating is applied to its surface to form an anti-carbonization environmentally friendly coating. However, this type of coating mostly uses organic substances as solvents, has a strong odor during construction, and has high production costs. The concrete is difficult to recycle and reuse after coating, and regular maintenance is required in the later stage.

[0005] According to the above analysis, the current prevention and control measures for concrete carbonation can improve the concrete's anti-carbonation ability to a certain extent, but they all have certain limitations and cannot fundamentally solve the concrete anti-carbonation problem. Therefore, it is necessary to develop an admixture that can prevent carbon dioxide from being transmitted in concrete, make the concrete dense and hydrophobic, and improve its anti-carbonation performance. Summary of the invention

[0006] In order to delay the carbonization destructive effect of carbon dioxide in the external environment on concrete, the present invention provides a concrete carbonization inhibitor, a preparation method and application.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] A concrete carbonization inhibitor, the raw materials for its preparation include the following components by weight:

[0009]

[0010] The modified calcium oxide is calcium oxide whose surface has been hydrophobically modified by siloxane.

[0011] The siloxane is one or a mixture of two or more of polydimethylsiloxane, tetramethyldisiloxane, hexamethyldisiloxane and heptamethyltrisiloxane, and the mass ratio of calcium oxide to siloxane is 10:1 to 20:1.

[0012] The specific preparation method of the modified calcium oxide comprises the following steps: mixing calcium oxide and siloxane, stirring for 10 to 20 minutes, drying the separated solid sample and then grinding it into fine powder to obtain the modified calcium oxide.

[0013] The organic silicon waterproofing agent is one of butyltrimethoxysilane, butyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, isooctyltriethoxysilane and propyltriethoxysilane, or a mixture of two or more thereof.

[0014] Furthermore, the alcohol amine is one or a mixture of two or more of ethanolamine, diethanolamine, triethanolamine, diethylenepropanolamine and methyldiethanolamine.

[0015] Furthermore, the polycarboxylate water reducer is one of TK-PCA type polycarboxylate high performance water reducer and SP-40 type polycarboxylate high performance water reducer.

[0016] Furthermore, the filler is a combination of one or more of silica sol, nano silicon dioxide, steel slag powder, barite powder, and corundum in any proportion.

[0017] Furthermore, the defoaming agent is a combination of one or more of n-butanol, polypropylene alcohol, tributyl phosphate, ethylene oxide, lecithin, magnesium hydroxide, and phosphate ester in any proportion.

[0018] On the other hand, the present invention also provides a method for preparing a tunnel lining concrete carbonization inhibitor, which specifically comprises the following steps:

[0019] (1) firstly, the modified calcium oxide, the polycarboxylate water reducer, the alcohol amine and the filler are uniformly mixed to obtain a premix A;

[0020] (2) Then, the premix, the organosilicon waterproofing agent and the defoaming agent are placed in a mixer and mixed evenly to obtain the concrete carbonization inhibitor.

[0021] The present invention also provides the application of the concrete carbonization inhibitor, wherein the concrete carbonization inhibitor is added to concrete in an amount of 5-10wt% of the mass of the cementitious material, and the concrete carbonization inhibitor does not replace the cementitious material.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) Calcium oxide is easily deteriorated by absorbing moisture in the air when exposed to air. The present invention can reduce its water absorption by hydrophobic modification of the surface of calcium oxide, thereby better ensuring the activity of calcium oxide, so that it can compete with hydrogen-modified calcium oxide to react with carbon dioxide, thereby improving the anti-carbonization performance of the carbonization inhibitor.

[0024] (2) The modified calcium oxide and alcohol amine of the present invention can react with carbon dioxide that penetrates into the interior of the concrete to form a dense calcium carbonate layer and an amino acid salt, respectively, to prevent the reaction of carbon dioxide to cement hydration products, wherein the calcium carbonate produced by the reaction of the modified calcium oxide can also fill the pores, play a role in compacting the concrete, and reduce the rate at which carbon dioxide further penetrates into the interior of the concrete. In addition, in the presence of water, the modified calcium oxide will also react with the alcohol amine to form an alcohol amine salt, which is an ionic compound with good surface activity and dispersibility, and can be evenly dispersed in the concrete pore fluid to promote the carbonation inhibitor to play a role.

[0025] (3) The concrete carbonization inhibitor of the present invention reduces the amount of carbon dioxide that penetrates by compacting concrete through fillers and modified calcium oxide reaction products, reduces the amount of water that is transferred into the concrete by adding waterproofing agents, and consumes the carbon dioxide that penetrates into the concrete through chemical reactions. Through the above-mentioned compaction, hydrophobicity and chemical bonding effects, the carbonization resistance of concrete is improved; the admixture can improve the carbonization resistance and long-term stability of concrete and effectively reduce the carbonization depth of concrete. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0027] Example 1

[0028] (1) Modified calcium oxide

[0029] Calcium oxide and polydimethylsiloxane were mixed and stirred at a weight ratio of 15:1 for 10 minutes, and then filtered with an organic filter membrane. The obtained solid sample was dried and then ground into fine powder to obtain modified calcium oxide.

[0030] (2) A concrete carbonation inhibitor, wherein the components are composed of the following components in parts by weight:

[0031] Modified calcium oxide: 50 parts,

[0032] Alcoholamine: 5 parts of ethanolamine,

[0033] Silicone waterproofing agent: 2 parts of butyltrimethoxysilane,

[0034] Polycarboxylate water reducer: 5 parts of TK-PCA type polycarboxylate high performance water reducer,

[0035] Filler: 5 parts of silica sol,

[0036] Defoaming agent: 2 parts of n-butanol.

[0037] (3) The specific preparation steps of the concrete carbonization inhibitor include: first, selecting each component according to the above mass fraction, and uniformly mixing the modified calcium oxide, polycarboxylic acid water-reducing agent, alcohol amine and filler to obtain a premix A; then placing the premix A, the silicone waterproofing agent and the defoaming agent in a high-speed mixer and mixing them uniformly to obtain the concrete carbonization inhibitor, which is recorded as S1.

[0038] Example 2

[0039] (1) Modified calcium oxide

[0040] Calcium oxide and tetramethyldisiloxane were mixed and stirred at a weight ratio of 10:1 for 15 minutes, and then filtered with an organic filter membrane. The obtained solid sample was dried and then ground into fine powder to obtain modified calcium oxide.

[0041] (2) A concrete carbonation inhibitor, wherein the components are composed of the following components in parts by weight:

[0042] Modified calcium oxide: 60 parts,

[0043] Alcoholamine: 2 parts of diethanolamine, 3 parts of triethanolamine,

[0044] Silicone waterproofing agent: 2 parts of butyl triethoxy silane, 1 part of isobutyl trimethoxy silane,

[0045] Polycarboxylate water reducer: 7 parts of SP-40 polycarboxylate high performance water reducer,

[0046] Filler: 5 parts of nano silicon dioxide, 7 parts of steel slag powder,

[0047] Defoaming agent: 1 part of polypropylene glycol and 2 parts of tributyl phosphate.

[0048] (3) The specific preparation steps of the concrete carbonization inhibitor include: first, selecting each component according to the above mass fraction, and uniformly mixing the modified calcium oxide, polycarboxylic acid water-reducing agent, alcohol amine and filler to obtain a premix A; then placing the premix A, silicone waterproofing agent and defoaming agent in a high-speed mixer and mixing them uniformly to obtain the concrete carbonization inhibitor, which is recorded as S2.

[0049] Example 3

[0050] (1) Modified calcium oxide

[0051] Calcium oxide and hexamethyldisiloxane were mixed and stirred at a weight ratio of 20:1 for 14 minutes, and then filtered with an organic filter membrane. The obtained solid sample was dried and then ground into fine powder to obtain modified calcium oxide.

[0052] (2) A tunnel lining concrete carbonization inhibitor, wherein the components are composed of the following components in parts by weight:

[0053] Modified calcium oxide: 70 parts,

[0054] Alcoholamine: 3 parts of diethylpropanolamine, 4 parts of methyldiethanolamine,

[0055] Silicone waterproofing agent: 2 parts of isobutyl triethoxysilane, 3 parts of octyl trimethoxysilane,

[0056] Polycarboxylate water reducer: 10 parts of TK-PCA type polycarboxylate high performance water reducer,

[0057] Filler: 10 parts of barite powder, 8 parts of corundum,

[0058] Defoaming agent: 2 parts of polypropylene alcohol, 1 part of tributyl phosphate, 1 part of magnesium hydroxide, and 1 part of phosphate ester.

[0059] (3) The specific preparation steps of the tunnel lining concrete carbonization inhibitor include: first, selecting each component according to the above mass fraction, and uniformly mixing the modified calcium oxide, polycarboxylic acid water-reducing agent, alcohol amine and filler to obtain a premix A; then, placing the premix A, the silicone waterproofing agent and the defoaming agent in a high-speed mixer and mixing them uniformly to obtain the concrete carbonization inhibitor, which is recorded as S3.

[0060] Example 4

[0061] (1) Modified calcium oxide

[0062] Calcium oxide and heptamethyltrisiloxane were mixed and stirred at a weight ratio of 13:1 for 12 minutes, and then filtered with an organic filter membrane. The obtained solid sample was dried and then ground into fine powder to obtain modified calcium oxide.

[0063] (2) A tunnel lining concrete carbonization inhibitor, wherein the components are composed of the following components in parts by weight:

[0064] Modified calcium oxide: 80 parts,

[0065] Alcoholamine: 3 parts of monoethanolamine, 3 parts of diethanolamine, 4 parts of triethanolamine,

[0066] Polycarboxylate water reducer: 10 parts of SP-40 polycarboxylate high performance water reducer,

[0067] Filler: 6 parts of silica sol, 7 parts of nano silicon dioxide, and 12 parts of steel slag powder.

[0068] (3) The specific preparation steps of the tunnel lining concrete carbonization inhibitor include: first, selecting each component according to the above mass fraction, and uniformly mixing the modified calcium oxide, polycarboxylic acid water reducer, alcohol amine and filler to obtain the concrete carbonization inhibitor, which is recorded as S4.

[0069] Comparative Example 1

[0070] This comparative example is set based on Example 1, except that no modified calcium oxide is added, and other conditions are consistent with Example 1.

[0071] (1) A tunnel lining concrete carbonization inhibitor, wherein the components are composed of the following components in parts by weight:

[0072] Alcoholamine: 5 parts of ethanolamine,

[0073] Silicone waterproofing agent: 2 parts of butyltrimethoxysilane,

[0074] Polycarboxylate water reducer: 5 parts of TK-PCA type polycarboxylate high performance water reducer,

[0075] Filler: 5 parts of silica sol,

[0076] Defoaming agent: 2 parts of n-butanol.

[0077] (2) The specific preparation steps of the tunnel lining concrete carbonization inhibitor include: first, selecting each component according to the above mass fraction, and mixing the polycarboxylic acid water reducer, alcohol amine and filler evenly to obtain a premix A; then placing the premix A, silicone waterproofing agent and defoaming agent in a high-speed mixer and mixing them evenly to obtain the concrete carbonization inhibitor, which is recorded as DS1.

[0078] Comparative Example 2

[0079] This comparative example is set based on Example 1, except that no alcohol amine is added, and other conditions are consistent with Example 1.

[0080] (1) Modified calcium oxide

[0081] Calcium oxide and polydimethylsiloxane were mixed and stirred at a weight ratio of 15:1 for 10 minutes, and then filtered with an organic filter membrane. The obtained solid sample was dried and then ground into fine powder to obtain modified calcium oxide.

[0082] (2) A tunnel lining concrete carbonization inhibitor, wherein the components are composed of the following components in parts by weight:

[0083] Modified calcium oxide: 50 parts,

[0084] Silicone waterproofing agent: 2 parts of butyltrimethoxysilane,

[0085] Polycarboxylate water reducer: 5 parts of TK-PCA type polycarboxylate high performance water reducer,

[0086] Filler: 5 parts of silica sol,

[0087] Defoaming agent: 2 parts of n-butanol.

[0088] (3) The specific preparation steps of the tunnel lining concrete carbonization inhibitor include: first, selecting each component according to the above mass fraction, and evenly mixing the modified calcium oxide, polycarboxylic acid water-reducing agent and filler to obtain a premix A; then, placing the premix A, the silicone waterproofing agent and the defoaming agent in a high-speed mixer and mixing them evenly to obtain the concrete carbonization inhibitor, which is recorded as DS2.

[0089] Application Examples

[0090] The concrete carbonization inhibitors prepared in Examples 1-4 and Comparative Examples 1-2 were added to concrete to test the compressive strength and carbonation resistance of the concrete test blocks. The concrete mix ratios are shown in Table 1, where the reference represents a blank group without the addition of the carbonization inhibitor.

[0091] Table 1 Concrete mix ratio

[0092]

[0093] Carbonization inhibitor dosage = 5-10wt% of the mass of the cementitious material and does not replace the cementitious material

[0094] Compressive strength test: Referring to the National Standard of the People's Republic of China GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", the concrete was demolded after 1 day of molding and cured in a standard curing room with a temperature of 20±2℃ and a humidity of more than 95%. The compressive strength of the concrete was measured after 28 days of standard curing. The specimen for the compressive strength test was a cube of 100mm×100mm×100mm, and the test results are shown in Table 2.

[0095]

[0096] As can be seen from Table 2, the 28d compressive strength of the concrete added with the concrete carbonization inhibitor of Examples 1-4 of the present invention is higher than that of the reference concrete without addition. In addition, the 28d compressive strength of the concrete in Examples 1-4 is also higher than that of the concrete in Comparative Examples 1-2, which shows that the concrete carbonization inhibitor has a good reinforcing effect and the inclusion of modified calcium oxide and alcohol amine can effectively increase its reinforcing effect.

[0097] Carbonation resistance test: After the concrete is formed for 1 day, the mold is removed, one pair of sides of the specimen is sealed with paraffin, and parallel lines are drawn along the length direction with a spacing of 10mm on the other pair of sides as carbonation depth test points. The treated specimens are placed in a carbonation test box (carbon dioxide concentration 20% ± 3%, temperature 20℃ ± 2℃, relative humidity 70% ± 5%), with a spacing of not less than 50mm; the carbon dioxide concentration, temperature and relative humidity are measured at intervals of 2h 2d before the test, and 4h thereafter. When the carbonization reaches 28d and 56d, the specimens are taken out and the carbonation depth is tested. The thickness of the test part each time is not less than half of the width of the specimen. After completion, the end face of the specimen is sealed with paraffin. Clean the powder from the cut part and drop a 1% alcohol phenolphthalein solution with a water content of 20%. After 30 seconds, test the carbonization depth d every 10 mm of the drawn line with an accuracy of 1 mm. If there are coarse aggregate particles on the carbonization boundary line, the average value on both sides of the particle can be taken as the carbonization depth of that point. The results are shown in Table 3.

[0098] Table 3 Concrete carbonization depth test results

[0099]

[0100] As shown in Table 3, the concrete carbonization inhibitors in Examples 1 to 4 of the present invention can effectively reduce the 28d and 56d carbonization depths of concrete. In addition, the improvement effect is also better than that of the concrete in Comparative Examples 1 to 2, which shows that the concrete carbonization inhibitor has a good anti-carbonization effect and the inclusion of modified calcium oxide and alcohol amine can effectively increase its anti-carbonization effect.

Claims

1. A concrete carbonization inhibitor, characterized in that: The raw materials for its preparation include the following components by weight: The modified calcium oxide is calcium oxide whose surface has been hydrophobically modified by siloxane.

2. The concrete carbonization inhibitor according to claim 1, characterized in that: The siloxane is one or a mixture of two or more of polydimethylsiloxane, tetramethyldisiloxane, hexamethyldisiloxane and heptamethyltrisiloxane, and the mass ratio of calcium oxide to siloxane is 10:1 to 20:

1.

3. The concrete carbonization inhibitor according to claim 1, characterized in that: The specific preparation method of the modified calcium oxide comprises the following steps: mixing calcium oxide and siloxane, stirring for 10 to 20 minutes, drying the separated solid sample and then grinding it into fine powder to obtain the modified calcium oxide.

4. The concrete carbonization inhibitor according to claim 1, characterized in that: The organic silicon waterproofing agent is one of butyltrimethoxysilane, butyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, isooctyltriethoxysilane and propyltriethoxysilane, or a mixture of two or more thereof.

5. The concrete carbonization inhibitor according to claim 1, characterized in that: The alcohol amine is one or a mixture of two or more of ethanolamine, diethanolamine, triethanolamine, diethylenepropanolamine and methyldiethanolamine.

6. The concrete carbonization inhibitor according to claim 1, characterized in that: The polycarboxylate water reducer is one of TK-PCA type polycarboxylate high performance water reducer and SP-40 type polycarboxylate high performance water reducer.

7. The concrete carbonization inhibitor according to claim 1, characterized in that: The filler is a combination of one or more of silica sol, nano silicon dioxide, steel slag powder, barite powder and corundum in any proportion.

8. The concrete carbonization inhibitor according to claim 1, characterized in that: The defoaming agent is a combination of one or more of n-butanol, polypropylene alcohol, tributyl phosphate, ethylene oxide, lecithin, magnesium hydroxide and phosphate ester in any proportion.

9. The method for preparing a concrete carbonization inhibitor according to any one of claims 1 to 8, characterized in that: (1) firstly, the modified calcium oxide, the polycarboxylate water reducer, the alcohol amine and the filler are uniformly mixed to obtain a premix A; (2) Then, the premix, the organosilicon waterproofing agent and the defoaming agent are placed in a mixer and mixed evenly to obtain the concrete carbonization inhibitor.

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