Retarder for concrete and preparation method thereof

Abstract

The invention provides a retarder for concrete and a preparation method thereof. The retarder is prepared from the following raw materials in parts by weight: 26 to 34 parts of modified pre-gelatinized starch, 5 to 8 parts of xanthan gum, 12 to 15 parts of calcium gluconate, 9 to 13 parts of pretreated silicon dioxide, 3 to 6 parts of diethanolisopropanolamine, 2 to 5 parts of hydroxyethyl cellulose, 1 to 3 parts of disodium ethylene diamine tetraacetate, 4 to 7 parts of polyglutamic acid, 2 to 3 parts of polyoxypropylene ether, 2 to 3 parts of acrylate and 20 to 30 parts of water. The retarder disclosed by the invention is compounded by taking modified pregelatinized starch, xanthan gum, calcium gluconate, pretreated silicon dioxide, polyglutamic acid, polyoxypropylene ether, acrylate and the like as raw materials, a layer of protective film can be formed on the surface of cement particles, the hydration process of cement is effectively prolonged, and concrete can also keep good fluidity; therefore, the setting time of the concrete is effectively prolonged. In addition, the retarder provided by the invention also can effectively inhibit the occurrence of microcracks of concrete, so that the concrete has good later strength.

Description

Technical Field

[0001] The invention relates to the technical field of concrete admixtures, and in particular to a retarder for concrete and a preparation method thereof. Background Art

[0002] Concrete is one of the most important materials in modern construction projects, and its performance directly affects the quality and service life of buildings. During the concrete construction process, especially in high temperature environments or long-distance transportation conditions, the setting time of concrete is often difficult to control, resulting in construction difficulties or reduced concrete strength. In order to solve this problem, retarders are widely used as an important concrete admixture. Retarders delay the cement hydration reaction, allowing concrete products to maintain good fluidity for a longer period of time, prolonging the setting time of concrete, thereby facilitating the construction of construction projects.

[0003] At present, the common concrete retarders on the market mainly include organic retarders such as sugars, phosphates, lignin sulfonates, and inorganic retarders such as zinc salts and borates. However, these retarders have certain limitations: although organic retarders have a good retarding effect, they are easily affected by ambient temperature and humidity, leading to corruption and deterioration, and have poor stability; although inorganic retarders have high stability, their retarding effect is usually limited by solubility, and they are sensitive to dosage. Once the dosage is too high, it may have a serious adverse effect on the later strength of concrete. Summary of the invention

[0004] In view of this, the present invention provides a retarder for concrete and a preparation method thereof. The concrete retarder of the present invention can effectively prolong the setting time of concrete and can also promote the improvement of the later strength of concrete.

[0005] The technical solution of the present invention is achieved in this way:

[0006] A retarder for concrete comprises the following raw materials in parts by weight: 26-34 parts of modified pregelatinized starch, 5-8 parts of xanthan gum, 12-15 parts of calcium gluconate, 9-13 parts of pretreated silicon dioxide, 3-6 parts of diethanol monoisopropanolamine, 2-5 parts of hydroxyethyl cellulose, 1-3 parts of disodium ethylenediaminetetraacetate, 4-7 parts of polyglutamic acid, 2-3 parts of polyoxypropylene ether, 2-3 parts of acrylate and 20-30 parts of water.

[0007] Furthermore, the retarder for concrete comprises the following raw materials in parts by weight: 34 parts of modified pregelatinized starch, 7 parts of xanthan gum, 15 parts of calcium gluconate, 13 parts of pretreated silica, 4 parts of diethanol monoisopropanolamine, 3 parts of hydroxyethyl cellulose, 2 parts of disodium ethylenediaminetetraacetate, 6 parts of polyglutamic acid, 3 parts of polyoxypropylene ether, 2.5 parts of acrylate, and 28 parts of water.

[0008] Furthermore, the preparation method of the modified pregelatinized starch is: heating water to 40-50°C, adding pregelatinized starch, stirring and mixing, then adding cationic polyacrylamide, stirring and mixing, and finally adding ethylene glycol dimethacrylate, stirring and mixing, so as to obtain the modified pregelatinized starch.

[0009] Furthermore, the mass ratio of the pregelatinized starch, water, cationic polyacrylamide and ethylene glycol dimethacrylate is 12-15:5-7:4-6:2-5.

[0010] Furthermore, the preparation method of the pretreated silicon dioxide is: adding nano silicon dioxide into a polyethylene glycol solution at a stirring speed of 500-700 r / min, and then adding a composite agent for ultrasonic treatment to obtain the pretreated silicon dioxide.

[0011] Furthermore, the mass ratio of the nano-silicon dioxide, the polyethylene glycol solution, and the composite agent is 5-8:1-2:4-5.

[0012] Furthermore, the concentration of the polyethylene glycol solution is 60-70wt%; the compound comprises calcium lignin sulfonate, Tween 80, and glyceryl monostearate in a mass ratio of 7-10:3-5:1-2.

[0013] Furthermore, the frequency of the ultrasonic treatment is 20-25kHz, the ultrasonic power is 100-150W, and the ultrasonic treatment time is 10-15min.

[0014] Furthermore, the polyoxypropylene ether is one or both of glycerol polyoxypropylene ether and fatty alcohol polyoxypropylene ether.

[0015] Furthermore, the acrylate is one or both of polyacrylate and methacrylate.

[0016] The preparation method of a retarder for concrete comprises the following steps:

[0017] S1. Add modified pregelatinized starch, xanthan gum and hydroxyethyl cellulose into water, stir and mix at 30-50° C. and 350-400 r / min to obtain a mixture;

[0018] S2. Add calcium gluconate, pretreated silicon dioxide, diethanol monoisopropanolamine, disodium ethylenediaminetetraacetate, polyglutamic acid, polyoxypropylene ether, and acrylate to the mixture, and stir and mix at 30-50° C. and a stirring speed of 600-700 r / min to obtain a retarder for concrete.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The retarder of the present invention is compounded with modified pregelatinized starch, xanthan gum, calcium gluconate, pretreated silicon dioxide, diethanol monoisopropanolamine, polyglutamic acid, polyoxypropylene ether, acrylate and the like as raw materials, and can form a protective film on the surface of cement particles, effectively prolong the hydration process of cement, and can also make concrete maintain good fluidity, thereby effectively prolonging the setting time of concrete. In addition, the retarder of the present invention can also effectively inhibit the occurrence of microcracks in concrete, and can significantly improve the later strength of concrete.

[0021] In the present invention, cationic polyacrylamide is used to modify the pregelatinized starch, which can form a mesh protection structure during the cement hydration process, thereby effectively playing a good role in water retention and slow setting. In addition, after the nano-silicon dioxide is pretreated with calcium lignin sulfonate, Tween 80, glyceryl monostearate, and polyethylene glycol, the dispersion of the nano-silicon dioxide in the concrete can be improved, the slow setting effect of the cement can be promoted, and the silicon dioxide can also penetrate into the pores of the concrete, improve the later strength of the concrete, and reduce the risks of cracking and cracking of the concrete. DETAILED DESCRIPTION

[0022] In order to better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0023] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods.

[0024] Unless otherwise specified, the materials, reagents, etc. used in the embodiments of the present invention can be obtained from commercial sources.

[0025] Example 1

[0026] A retarder for concrete comprises the following raw materials in parts by weight: 26 parts of modified pregelatinized starch, 8 parts of xanthan gum, 12 parts of calcium gluconate, 9 parts of pretreated silicon dioxide, 6 parts of diethanol monoisopropanolamine, 4 parts of hydroxyethyl cellulose, 1 part of disodium ethylenediaminetetraacetate, 7 parts of polyglutamic acid, 2 parts of polyoxypropylene ether, 3 parts of acrylate, and 20 parts of water; the polyoxypropylene ether is glycerol polyoxypropylene ether; and the acrylate is composed of polyacrylate and methacrylate in a mass ratio of 3:1.

[0027] The preparation method of the modified pregelatinized starch comprises: heating water to 45° C., adding the pregelatinized starch, stirring and mixing at a rotation speed of 120 r / min, then adding cationic polyacrylamide, stirring and mixing at a rotation speed of 280 r / min, and finally adding ethylene glycol dimethacrylate, stirring and mixing at a rotation speed of 280 r / min, so as to obtain the modified pregelatinized starch; the mass ratio of the pregelatinized starch, water, cationic polyacrylamide and ethylene glycol dimethacrylate is 15:6:4:2.

[0028] The preparation method of the pretreated silicon dioxide comprises the following steps: adding nano silicon dioxide to a polyethylene glycol solution at a stirring speed of 700 r / min, and then adding a composite agent to perform ultrasonic treatment for 10 minutes at a frequency of 20 kHz and an ultrasonic power of 100 W, so as to obtain the pretreated silicon dioxide; the mass ratio of the nano silicon dioxide, the polyethylene glycol solution and the composite agent is 7:1:5; the concentration of the polyethylene glycol solution is 60 wt%; and the composite agent comprises calcium lignin sulfonate, Tween 80 and glyceryl monostearate in a mass ratio of 9:5:1.

[0029] The preparation method of a retarder for concrete comprises the following steps:

[0030] S1. Add modified pregelatinized starch, xanthan gum and hydroxyethyl cellulose into water, and stir and mix at 50° C. and 400 r / min to obtain a mixture;

[0031] S2. Add calcium gluconate, pretreated silica, diethanol monoisopropanolamine, disodium ethylenediaminetetraacetate, polyglutamic acid, polyoxypropylene ether, and acrylate to the mixture, and stir and mix at 50° C. and a stirring speed of 600 r / min to obtain a retarder for concrete.

[0032] Example 2

[0033] A retarder for concrete comprises the following raw materials in parts by weight: 30 parts of modified pregelatinized starch, 5 parts of xanthan gum, 13 parts of calcium gluconate, 10 parts of pretreated silicon dioxide, 3 parts of diethanol monoisopropanolamine, 5 parts of hydroxyethyl cellulose, 3 parts of disodium ethylenediaminetetraacetate, 5 parts of polyglutamic acid, 2 parts of polyoxypropylene ether, 3 parts of acrylate, and 30 parts of water; the polyoxypropylene ether is fatty alcohol polyoxypropylene ether; and the acrylate is methacrylate.

[0034] The preparation method of the modified pregelatinized starch comprises: heating water to 40° C., adding pregelatinized starch, stirring and mixing at a rotation speed of 150 r / min, then adding cationic polyacrylamide, stirring and mixing at a rotation speed of 200 r / min, and finally adding ethylene glycol dimethacrylate, stirring and mixing at a rotation speed of 200 r / min, so as to obtain the modified pregelatinized starch; the mass ratio of the pregelatinized starch, water, cationic polyacrylamide and ethylene glycol dimethacrylate is 12:5:6:3.

[0035] The preparation method of the pretreated silicon dioxide comprises the following steps: adding nano silicon dioxide to a polyethylene glycol solution at a stirring speed of 500 r / min, and then adding a composite agent and performing ultrasonic treatment for 15 minutes under the conditions of a frequency of 22 kHz and an ultrasonic power of 150 W to obtain the pretreated silicon dioxide; the mass ratio of the nano silicon dioxide, the polyethylene glycol solution and the composite agent is 5:2:4; the concentration of the polyethylene glycol solution is 68 wt%; and the composite agent comprises calcium lignin sulfonate, Tween 80 and glyceryl monostearate in a mass ratio of 10:3:2.

[0036] The preparation method of a retarder for concrete comprises the following steps:

[0037] S1. Add modified pregelatinized starch, xanthan gum and hydroxyethyl cellulose into water, and stir and mix at 45° C. and 350 r / min to obtain a mixture;

[0038] S2. Add calcium gluconate, pretreated silica, diethanol monoisopropanolamine, disodium ethylenediaminetetraacetate, polyglutamic acid, polyoxypropylene ether, and acrylate to the mixture, stir and mix at 45° C. and a stirring speed of 600-700 r / min to obtain a retarder for concrete.

[0039] Example 3

[0040] A retarder for concrete comprises the following raw materials in parts by weight: 34 parts of modified pregelatinized starch, 7 parts of xanthan gum, 15 parts of calcium gluconate, 13 parts of pretreated silicon dioxide, 4 parts of diethanol monoisopropanolamine, 3 parts of hydroxyethyl cellulose, 2 parts of disodium ethylenediaminetetraacetate, 6 parts of polyglutamic acid, 3 parts of polyoxypropylene ether, 2.5 parts of acrylate, and 28 parts of water; the polyoxypropylene ether is composed of glycerol polyoxypropylene ether and fatty alcohol polyoxypropylene ether in a mass ratio of 1:1; the acrylate is polyacrylate.

[0041] The preparation method of the modified pregelatinized starch comprises: heating water to 50° C., adding the pregelatinized starch, stirring and mixing at a rotation speed of 180 r / min, then adding cationic polyacrylamide, stirring and mixing at a rotation speed of 260 r / min, and finally adding ethylene glycol dimethacrylate, stirring and mixing at a rotation speed of 260 r / min, so as to obtain the modified pregelatinized starch; the mass ratio of the pregelatinized starch, water, cationic polyacrylamide and ethylene glycol dimethacrylate is 13:7:5:4.

[0042] The preparation method of the pretreated silicon dioxide comprises the following steps: adding nano silicon dioxide to a polyethylene glycol solution at a stirring speed of 600 r / min, and then adding a composite agent and performing ultrasonic treatment for 13 minutes under the conditions of a frequency of 25 kHz and an ultrasonic power of 150 W to obtain the pretreated silicon dioxide; the mass ratio of the nano silicon dioxide, the polyethylene glycol solution and the composite agent is 8:2:4.5; the concentration of the polyethylene glycol solution is 70 wt%; and the composite agent comprises calcium lignin sulfonate, Tween 80 and glyceryl monostearate in a mass ratio of 8:4:2.

[0043] The preparation method of a retarder for concrete comprises the following steps:

[0044] S1. Add modified pregelatinized starch, xanthan gum and hydroxyethyl cellulose into water, and stir and mix at 40° C. and 380 r / min to obtain a mixture;

[0045] S2. Add calcium gluconate, pretreated silica, diethanol monoisopropanolamine, disodium ethylenediaminetetraacetate, polyglutamic acid, polyoxypropylene ether, and acrylate to the mixture, and stir and mix at 40° C. and a stirring speed of 700 r / min to obtain a retarder for concrete.

[0046] Comparative Example 1

[0047] The difference between this comparative example and Example 3 is that the raw material ratio of the retarder is different, and the rest is consistent with Example 3.

[0048] The retarder for concrete in this comparative example comprises the following raw materials in parts by weight: 16 parts of modified pregelatinized starch, 19 parts of xanthan gum, 21 parts of calcium gluconate, 7 parts of pretreated silica, 1 part of diethanol monoisopropanolamine, 1 part of hydroxyethyl cellulose, 0.5 parts of disodium ethylenediaminetetraacetate, 9 parts of polyglutamic acid, 7 parts of polyoxypropylene ether, 8 parts of acrylate, and 28 parts of water.

[0049] Comparative Example 2

[0050] The difference between this comparative example and Example 3 is that the pregelatinized starch is not modified, and the rest is consistent with Example 3.

[0051] A retarder for concrete comprises the following raw materials in parts by weight: 34 parts of pregelatinized starch, 7 parts of xanthan gum, 15 parts of calcium gluconate, 13 parts of pretreated silicon dioxide, 4 parts of diethanol monoisopropanolamine, 3 parts of hydroxyethyl cellulose, 2 parts of disodium ethylenediaminetetraacetate, 6 parts of polyglutamic acid, 3 parts of polyoxypropylene ether, 2.5 parts of acrylate, and 28 parts of water; the polyoxypropylene ether is composed of glycerol polyoxypropylene ether and fatty alcohol polyoxypropylene ether in a mass ratio of 1:1; and the acrylate is polyacrylate.

[0052] The preparation method of the pretreated silicon dioxide comprises the following steps: adding nano silicon dioxide to a polyethylene glycol solution at a stirring speed of 600 r / min, and then adding a composite agent and performing ultrasonic treatment for 13 minutes under the conditions of a frequency of 25 kHz and an ultrasonic power of 150 W to obtain the pretreated silicon dioxide; the mass ratio of the nano silicon dioxide, the polyethylene glycol solution and the composite agent is 8:2:4.5; the concentration of the polyethylene glycol solution is 70 wt%; and the composite agent comprises calcium lignin sulfonate, Tween 80 and glyceryl monostearate in a mass ratio of 8:4:2.

[0053] The preparation method of a retarder for concrete comprises the following steps:

[0054] S1. Add pregelatinized starch, xanthan gum and hydroxyethyl cellulose into water and stir at 40° C. and 380 r / min to obtain a mixture;

[0055] S2. Add calcium gluconate, pretreated silica, diethanol monoisopropanolamine, disodium ethylenediaminetetraacetate, polyglutamic acid, polyoxypropylene ether, and acrylate to the mixture, and stir and mix at 40° C. and a stirring speed of 700 r / min to obtain a retarder for concrete.

[0056] Comparative Example 3

[0057] The difference between this comparative example and Example 3 is that the silicon dioxide is not pretreated, and the rest is consistent with Example 3.

[0058] The comparative example is a retarder for concrete, comprising the following raw materials in parts by weight: 34 parts of modified pregelatinized starch, 7 parts of xanthan gum, 15 parts of calcium gluconate, 13 parts of silicon dioxide, 4 parts of diethanol monoisopropanolamine, 3 parts of hydroxyethyl cellulose, 2 parts of disodium ethylenediaminetetraacetate, 6 parts of polyglutamic acid, 3 parts of polyoxypropylene ether, 2.5 parts of acrylate, and 28 parts of water; the polyoxypropylene ether is composed of glycerol polyoxypropylene ether and fatty alcohol polyoxypropylene ether in a mass ratio of 1:1; the acrylate is polyacrylate.

[0059] The preparation method of the modified pregelatinized starch comprises: heating water to 50° C., adding the pregelatinized starch, stirring and mixing at a rotation speed of 180 r / min, then adding cationic polyacrylamide, stirring and mixing at a rotation speed of 260 r / min, and finally adding ethylene glycol dimethacrylate, stirring and mixing at a rotation speed of 260 r / min, so as to obtain the modified pregelatinized starch; the mass ratio of the pregelatinized starch, water, cationic polyacrylamide and ethylene glycol dimethacrylate is 13:7:5:4.

[0060] The preparation method of a retarder for concrete comprises the following steps:

[0061] S1. Add modified pregelatinized starch, xanthan gum and hydroxyethyl cellulose into water, and stir and mix at 40° C. and 380 r / min to obtain a mixture;

[0062] S2. Add calcium gluconate, silicon dioxide, diethanol monoisopropanolamine, disodium ethylenediaminetetraacetate, polyglutamic acid, polyoxypropylene ether, and acrylate to the mixture, and stir and mix at 40° C. and a stirring speed of 700 r / min to obtain a retarder for concrete.

[0063] The retarders prepared in the above Examples 1-3 and Comparative Examples 1-3 were used for concrete performance tests. Concrete formula (kg / m 3 )as follows:

[0064] cement Fly ash Machine-made sand Stone water 420 80 715 1100 155

[0065] The retarder parameter of Examples 1-3 and Comparative Examples 1-3 is 0.3% of the mass of concrete; the test method for initial setting time and final setting time of concrete is carried out in accordance with GB / T50080-2016 "Standard Test Method for Performance of Ordinary Concrete Mixtures"; the compressive strength of concrete is carried out according to the method specified in GB / T50081-2019 "Standard Test Method for Physical and Mechanical Properties of Concrete", and the test results are shown in the following table.

[0066]

[0067] The above results show that the retarders of Examples 1-3 of the present invention are compounded with modified pregelatinized starch, xanthan gum, calcium gluconate, pretreated silica, diethanol monoisopropanolamine, polyglutamic acid, polyoxypropylene ether, acrylate, etc. as raw materials, and can form a protective film on the surface of cement particles, effectively prolong the hydration process of cement, and can also make the concrete maintain good fluidity, thereby effectively prolonging the setting time of concrete, and can also make the concrete maintain good strength in the later stage, and the effect is good. Compared with Example 3, Comparative Example 1 changes the raw material ratio of the retarder, Comparative Example 2 does not modify the pregelatinized starch, and Comparative Example 3 does not pretreat the silica, resulting in a decrease in the effect of the retarder and also affecting the later strength of the concrete.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A retarder for concrete, characterized in that: The invention comprises the following raw materials in parts by weight: 26-34 parts of modified pregelatinized starch, 5-8 parts of xanthan gum, 12-15 parts of calcium gluconate, 9-13 parts of pretreated silicon dioxide, 3-6 parts of diethanol monoisopropanolamine, 2-5 parts of hydroxyethyl cellulose, 1-3 parts of disodium ethylenediaminetetraacetate, 4-7 parts of polyglutamic acid, 2-3 parts of polyoxypropylene ether, 2-3 parts of acrylate and 20-30 parts of water.

2. The retarder for concrete according to claim 1, characterized in that: The invention comprises the following raw materials in parts by weight: 34 parts of modified pregelatinized starch, 7 parts of xanthan gum, 15 parts of calcium gluconate, 13 parts of pretreated silicon dioxide, 4 parts of diethanol monoisopropanolamine, 3 parts of hydroxyethyl cellulose, 2 parts of disodium ethylenediaminetetraacetate, 6 parts of polyglutamic acid, 3 parts of polyoxypropylene ether, 2.5 parts of acrylate and 28 parts of water.

3. The retarder for concrete according to claim 1, characterized in that: The preparation method of the modified pregelatinized starch is as follows: heating water to 40-50° C., adding the pregelatinized starch, stirring and mixing, then adding cationic polyacrylamide, stirring and mixing, and finally adding ethylene glycol dimethacrylate, stirring and mixing, so as to obtain the modified pregelatinized starch.

4. The retarder for concrete according to claim 3, characterized in that: The mass ratio of the pregelatinized starch, water, cationic polyacrylamide and ethylene glycol dimethacrylate is 12-15:5-7:4-6:2-5.

5. The retarder for concrete according to claim 1, characterized in that: The preparation method of the pretreated silicon dioxide is as follows: adding nano silicon dioxide into a polyethylene glycol solution at a stirring speed of 500-700 r / min, and then adding a composite agent for ultrasonic treatment to obtain the pretreated silicon dioxide.

6. The retarder for concrete according to claim 5, characterized in that: The mass ratio of the nano silicon dioxide, the polyethylene glycol solution and the composite agent is 5-8:1-2:4-5.

7. The retarder for concrete according to claim 5, characterized in that: The concentration of the polyethylene glycol solution is 60-70wt%; the compounding agent comprises calcium lignin sulfonate, Tween 80 and glyceryl monostearate in a mass ratio of 7-10:3-5:1-2.

8. The retarder for concrete according to claim 5, characterized in that: The frequency of the ultrasonic treatment is 20-25kHz, the ultrasonic power is 100-150W, and the ultrasonic treatment time is 10-15min.

9. The retarder for concrete according to claim 1, characterized in that: The polyoxypropylene ether is one or both of glycerol polyoxypropylene ether and fatty alcohol polyoxypropylene ether; the acrylate is one or both of polyacrylate and methacrylate.

10. The method for preparing a retarder for concrete according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Add modified pregelatinized starch, xanthan gum and hydroxyethyl cellulose into water, stir and mix at 30-50° C. and 350-400 r / min to obtain a mixture; S2. Add calcium gluconate, pretreated silicon dioxide, diethanol monoisopropanolamine, disodium ethylenediaminetetraacetate, polyglutamic acid, polyoxypropylene ether, and acrylate to the mixture, and stir and mix at 30-50° C. and a stirring speed of 600-700 r / min to obtain a retarder for concrete.

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