A concrete shrinkage reducing admixture and a preparation method thereof

Abstract

The present application relates to a kind of concrete shrinkage reducing agent and its preparation method, belong to concrete admixture technical field.The concrete shrinkage reducing agent is composed of shrinkage component and auxiliary component according to mass ratio (55-75) :(25-45) ;Wherein, shrinkage component is with polymethyl hydrogen siloxane and modified polyether as raw material, is prepared by polyether modified silicone at 75-95 ℃ under reaction 4h-8h, auxiliary component is ether and / or polyhydric alcohol;The molar ratio of Si-H in the polymethyl hydrogen siloxane and C=C in the modified polyether is (0.8-1.2) :(1.1-1.5) ;The shrinkage reducing agent reduces the surface tension in cement concrete pore solution by the synergistic unified action of shrinkage component and auxiliary component, reduces the driving force of shrinkage stress sending, can still achieve excellent shrinkage effect under the condition of low dosage in concrete;The preparation method of the concrete shrinkage reducing agent process step is simple, and it is convenient for batch production.

Description

TECHNICAL FIELD

[0001] The present application relates to a concrete shrinkage reducing agent and a preparation method thereof, and belongs to the technical field of concrete admixtures. BACKGROUND

[0002] Mortar, ordinary concrete and ultra-high performance concrete (UHPC) undergo volume shrinkage during setting and drying, which has an adverse effect on the service life and strength of the building. For example, in reinforced concrete structures, concrete volume shrinkage can cause cracks, screed depressions and other defects, water, dissolved salts and air can enter the interior of the concrete, mortar, screed or paste through the cracks and promote corrosion, in addition, the periodic stress caused by water entering from the cracks-ice-melting also causes mechanical stress and early material failure. Therefore, shrinkage reducing agents are usually added to concrete to reduce or overcome the above problems.

[0003] Patent CN113227014B discloses using an adduct of a polyether amine and a compound containing an epoxy group as a shrinkage reducing agent; patent application CN115403712A discloses using an alcohol-based shrinkage reducing functional monomer and fibers together to be introduced into a polycarboxylic acid water reducing agent structure to prepare a shrinkage reducing agent; patent CN112830704B discloses using maleic anhydride, polyethylene glycol and polypropylene glycol as raw materials to prepare a shrinkage reducing agent through esterification and polymerization reaction; however, the above-mentioned shrinkage reducing agents may damage the effects of other additives or are not conducive to the development of the strength of the cement-based system due to their high dosage and / or high production cost when added to concrete in actual application. SUMMARY

[0004] In order to overcome the defects existing in the prior art, one of the purposes of the present application is to provide a concrete shrinkage reducing agent, which is composed of a shrinkage reducing component polyether modified organosilicon and an auxiliary component ether and / or polyol, and through the synergistic and unified action of the shrinkage reducing component and the auxiliary component, a significant shrinkage reducing effect can still be produced under the condition of low dosage in concrete;

[0005] The second purpose of the present application is to provide a preparation method of a concrete shrinkage reducing agent, which has simple process steps and is convenient for batch production.

[0006] The purpose of the present application is achieved by the following technical solutions.

[0007] A concrete shrinkage reducing agent, which is composed of a shrinkage reducing component and an auxiliary component in a mass ratio of (55-75):(25-45);

[0008] The shrinkage reducing component is a polyether modified organosilicon prepared by reacting polymethylhydrogen siloxane and modified polyether at 75-95 DEG C for 4-8 hours;

[0009] The general formula of the modified polyether is CH2=CH-CH2-R1-R2-R3, wherein R1 is -(OC2H4) a -(OC3H6) b -, R2 is -OOC(CH2) c -, R3 is -COOH, -NH2 or -OH; a, b, c are all positive integers greater than 1.

[0010] The molar ratio of Si-H in the polymethylhydrogen siloxane to C=C in the modified polyether is (0.8-1.2):(1.1-1.5).

[0011] The auxiliary component is an ether and / or a polyhydric alcohol.

[0012] Preferably, the molecular weight (Mw) of the polymethylhydrogen siloxane is 200-1000 g / mol; the molecular weight (Mw) of the modified polyether is 200-1000 g / mol.

[0013] Preferably, the molecular weight (Mw) of the polyether-modified organosilicon is 200-10000 g / mol; the auxiliary component is at least one of 2-methyl-2,4-pentanediol, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, diethylene glycol monomethyl ether and polyethylene glycol monomethyl ether.

[0014] Further preferably, the molecular weight (Mw) of the polyether-modified organosilicon is 200-1000 g / mol; the auxiliary component is 2-methyl-2,4-pentanediol and polyethylene glycol monomethyl ether with a molecular weight of 200 g / mol in a mass ratio of 1:1.

[0015] Preferably, the dosage of the shrinkage reducing agent in the concrete is 0.5%-1.5% of the mass of the cementitious material in the concrete.

[0016] A preparation method of the concrete shrinkage reducing agent according to the present application, the steps of the method are as follows:

[0017] (1) Taking polymethylhydrogen siloxane and modified polyether as raw materials, isopropyl alcohol as a solvent, the polymethylhydrogen siloxane and the modified polyether are added into isopropyl alcohol, and reacted at 75-95°C for 4-8h, and then the solvent is removed by distillation under reduced pressure to obtain the shrinkage reducing component polyether-modified organosilicon.

[0018] The mass of the solvent isopropyl alcohol is 30% of the total mass of the raw materials.

[0019] (2) The shrinkage reducing component obtained in step (1) is mixed with the auxiliary component to obtain the concrete shrinkage reducing agent.

[0020] Preferably, the solvent is removed by distillation at 60°C under reduced pressure for 1h.

[0021] Advantages

[0022] (1) The present application provides a concrete shrinkage reducing agent, which is composed of a shrinkage reducing component and an auxiliary component; wherein the shrinkage reducing component is a polyether modified silicone, and the shrinkage reducing component is an ether and / or a polyol; through the synergistic and unified action of the shrinkage reducing component and the auxiliary component, the surface tension in the cement concrete pore solution is reduced, and the driving force for shrinkage stress occurrence is reduced, so as to achieve excellent shrinkage reducing effect.

[0023] (2) The present application provides a concrete shrinkage reducing agent, compared with the polyol ether commonly used in the prior art concrete shrinkage reducing agent, the shrinkage reducing component of the present application uses a polyether modified silicone, which has lower surface tension and is not flammable, thereby increasing the water solubility of the concrete water reducing agent and improving the shrinkage reducing effect.

[0024] (3) The present application provides a concrete shrinkage reducing agent, the raw materials of the shrinkage reducing component polyether modified silicone are preferably polymethyl hydrogen siloxane with a molecular weight of 200g / mol-1000g / mol and modified polyether with a molecular weight of 200-1000g / mol, and the polymethyl hydrogen siloxane and modified polyether in the above molecular weight range are fully dissolved / dispersed in the solvent, thereby fully improving the yield of the polyether modified silicone.

[0025] (4) The present application provides a preparation method of a concrete shrinkage reducing agent, which first prepares polyether modified silicone with polymethyl hydrogen siloxane and modified polyether as raw materials, and then uniformly mixes the polyether modified silicone and the auxiliary component to obtain a concrete shrinkage reducing agent liquid; the method has simple preparation process, is easy to mass produce, and has high reaction efficiency. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be described below in conjunction with specific embodiments, and the methods are all conventional methods unless otherwise specified, and the raw materials can be obtained from public commercial channels unless otherwise specified.

[0027] Example 1

[0028] A preparation method of a concrete shrinkage reducing agent, the steps of the method are as follows:

[0029] (1) Polymethyl hydrogen siloxane and modified polyether are used as raw materials, isopropyl alcohol is used as a solvent, the polymethyl hydrogen siloxane and the modified polyether are added into isopropyl alcohol, and the mixture is reacted at 75°C for 8h; after the reaction is completed, the solvent is removed by distillation at 60°C under reduced pressure for 1h, and the product is obtained;

[0030] The molecular weight (Mw) of the modified polyether is 810 g / mol, and the molecular formula is CH2=CH-CH2-(OC2H4)5-(OC3H6)6-OOC(CH2)8-COOH;

[0031] The molecular weight (Mw) of the polymethyl hydrogen siloxane is 832 g / mol, and the molecular formula is (CH3)3SiO-(CH3SiOCH3)5-(CH3SiOH)5-Si(CH3)3;

[0032] The ratio of the molar amount of Si-H in the polymethyl hydrogen siloxane to C=C in the modified polyether is 1:1;

[0033] The mass of the solvent isopropyl alcohol is 30% of the total mass of raw materials;

[0034] The product is characterized by infrared spectrum, and the Si-C bond characteristic absorption peak is at 1261 cm -1 -1, the Si-O-Si, Si-O-C, C-O-C bond absorption peak is at 1091 cm -1 -1, the polyether segment and the polysiloxane segment appear in the polyether modified organosilicon, and the Si-H bond absorption peak at 2154 cm -1 -1 does not appear, indicating that the Si-H bond and the C=C bond have undergone a silicon hydrogen addition reaction, thereby proving that the product is the shrinkage reducing component polyether modified organosilicon;

[0035] (2) The shrinkage reducing component obtained in step (1) is mixed with the auxiliary component according to a mass ratio of 75:25 to obtain the concrete shrinkage reducing agent.

[0036] The auxiliary component is composed of 2-methyl-2,4-pentanediol, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, diethylene glycol monomethyl ether, polyethylene glycol monomethyl ether with a molecular weight of 500 g / mol, and polyethylene glycol monomethyl ether with a molecular weight of 200 g / mol, according to a mass ratio of 7.5:2.5:2.5:2.5:5:5.

[0037] Example 2

[0038] Example 2 is only based on Example 1, the auxiliary component in step (2) is replaced from "2-methyl-2,4-pentanediol, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, diethylene glycol monomethyl ether, polyethylene glycol monomethyl ether with a molecular weight of 500 g / mol and polyethylene glycol monomethyl ether with a molecular weight of 200 g / mol in a mass ratio of 7.5:2.5:2.5:2.5:5:5" to "2-methyl-2,4-pentanediol and polyethylene glycol monomethyl ether with a molecular weight of 200 g / mol in a mass ratio of 12.5:12.5", and the mass ratio of the reducing component and the auxiliary component is replaced from "75:25" to "60:25", and the other conditions remain unchanged.

[0039] Example 3

[0040] Example 3 is only based on Example 1, the auxiliary component in step (2) is replaced from "2-methyl-2,4-pentanediol, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, diethylene glycol monomethyl ether, polyethylene glycol monomethyl ether with a molecular weight of 500 g / mol and polyethylene glycol monomethyl ether with a molecular weight of 200 g / mol in a mass ratio of 7.5:2.5:2.5:2.5:5:5" to "2-methyl-2,4-pentanediol, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, diethylene glycol monomethyl ether, polyethylene glycol monomethyl ether with a molecular weight of 500 g / mol and polyethylene glycol monomethyl ether with a molecular weight of 200 g / mol in a mass ratio of 5:5:10:5:10:10", and the mass ratio of the reducing component and the auxiliary component is replaced from "75:25" to "55:45", and the other conditions remain unchanged.

[0041] Example 4

[0042] Example 4 is only based on Example 1, the structural formula of the modified polyether is replaced from "CH2=CH-CH2-(OC2H4)5-(OC3H6)6-OOC(CH2)8-COOH with a molecular weight of 800 g / mol" to "CH2=CH-CH2-(OC2H4)5-(OC3H6)6-OOC(CH2)8-NH2 with a molecular weight of 781 g / mol", and "reacting at 75°C for 8h" is replaced by "reacting at 95°C for 4h", and the other conditions remain unchanged.

[0043] Comparative Example 1

[0044] Comparative Example 1 is only based on Example 1, the auxiliary component is removed, and the other conditions remain unchanged.

[0045] Comparative Example 2

[0046] Comparative Example 2 is only based on Example 1, the reducing component is removed, and the other conditions remain unchanged.

[0047] According to the standard JCT 2361-2016 Mortar, Concrete Shrinkage Reducing Admixture, the performance test was carried out by adding the shrinkage reducing admixtures prepared by the following comparative examples and examples to C50 concrete, the shrinkage reducing admixture was added in an amount of 1% of the cementitious material in the C50 concrete, and the results are shown in Table 1, wherein " / " represents that the test was not carried out, the reference sample is C50 concrete, without adding shrinkage reducing admixtures or auxiliary components, therefore the reference sample does not carry out 28d shrinkage rate test:

[0048] Table 1 Performance test results of water reducing agent of comparative examples 1-2 and examples 1-5

[0049]

[0050] The test results show that, compared with the reference sample, the concrete cracking area of the concrete added with the concrete water reducing agent of the present application is significantly reduced, and the stability and shrinkage rate are significantly improved.

[0051] The above only describes specific embodiments of the present application and is not used to limit the protection scope of the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A concrete shrinkage reducing admixture characterized by: The concrete shrinkage reducing agent is composed of a shrinkage reducing component and an auxiliary component according to a mass ratio of (55-75):(25-45); The shrinkage reducing component is a polyether modified silicone prepared by reacting polymethyl hydrogen siloxane and modified polyether at 75-95 DEG C for 4-8 hours; CH2=CH-CH2-R1-R2-R3, wherein R1 is -(OC2H4)a a -(OC3H6)b b -, R2 is -OOC(CH2)c c -, R3 is -COOH, -NH2 or -OH; a, b, c are each positive integers greater than 1; The molar ratio of Si-H in the polymethyl hydrogen siloxane to C=C in the modified polyether is (0.8-1.2):(1.1-1.5); The molecular weight of the polyether modified silicone is 200-10000 g / mol; The auxiliary component is at least one of 2-methyl-2,4-pentanediol, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, diethylene glycol monomethyl ether and polyethylene glycol monomethyl ether.

2. The concrete shrinkage reducing admixture according to claim 1, wherein: The molecular weight of the polyether modified silicone is 200-1000 g / mol; and the auxiliary component is 2-methyl-2,4-pentanediol and polyethylene glycol monomethyl ether with a molecular weight of 200 g / mol according to a mass ratio of 1:

1.

3. The concrete shrinkage reducing admixture according to claim 1, wherein: The molecular weight of the polymethyl hydrogen siloxane is 200-1000 g / mol; and the molecular weight of the modified polyether is 200-1000 g / mol.

4. The concrete shrinkage reducing admixture according to claim 1, wherein: The doping amount of the shrinkage reducing agent in the concrete is 0.5-1.5% of the mass of the cementing material in the concrete.

5. A method of preparing the concrete shrinkage reducing admixture according to any one of claims 1 to 4, characterized by: The method steps are as follows: (1) using polymethyl hydrogen siloxane and modified polyether as raw materials, isopropyl alcohol as a solvent, the polymethyl hydrogen siloxane and the modified polyether are added into isopropyl alcohol, and reacted at 75-95 DEG C for 4-8 hours; after the reaction, the solvent is removed by reduced pressure distillation to obtain the shrinkage reducing component polyether modified silicone; The mass of the solvent isopropyl alcohol is 30% of the total mass of the raw materials; (2) the shrinkage reducing component is mixed with the auxiliary component to obtain the concrete shrinkage reducing agent.

6. The method of claim 5, wherein the method further comprises: adding the shrinkage reducing admixture to the cementitious mixture. The solvent is removed by reduced pressure distillation at 60 DEG C for 1 hour.

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