An anti-segregation water reducer for concrete with anti-over-retarding property and its preparation method

Abstract

The present invention discloses an anti-segregation water reducer for anti-over-retarding concrete and its preparation method. The anti-segregation water reducer comprises 4-6 parts of guar gum powder, 20-30 parts of aluminum sulfate octadecahydrate, 2-4 parts of sodium thiosulfate, 60-70 parts of naphthalene-based high-range water reducer, 0.5-1.5 parts of hydroxypropyl methyl cellulose ether, and 0.5-2 parts of sodium dodecyl sulfate. The anti-segregation water reducer provided by the present invention can be used in the situation where the segregation of concrete occurs due to excessive slump retention components in the admixture during concrete construction, affecting the normal pouring of concrete. The segregation problem of fresh concrete can be solved by the anti-segregation water reducer of the present invention, and the control level of the construction performance of fresh concrete can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly relates to an anti-bleeding agent for anti-over-retarding concrete and a preparation method thereof. Background Art

[0002] Before the production of concrete, mix proportion design, third-party verification, etc. are all key points of concrete quality control technology. However, in the daily production of concrete, the mix proportion of concrete is not fixed. With the fluctuations of raw materials, the concrete also needs to be slightly adjusted. The principle of adjustment is to ensure that the water-cement ratio remains unchanged and the strength is ensured, and through the fine adjustment of water and admixtures, the workability of the fresh concrete meets the construction technical requirements. Thus, it can be seen that admixtures play a crucial role in concrete. In order to minimize the loss of fluidity of concrete from the production and ex-factory to the pouring period, a slump retention agent is generally added to the admixture. The amount of slump retention agent added mainly depends on the water demand of the cementitious material and the aggregate. If its adsorption property is strong, the proportion of the slump retention agent required is more. During the application of sand and gravel, its physical properties often change. Sometimes, due to the relatively large amount of slump retention agent component, the workability state of the concrete is in a good state when it is discharged from the production, but bleeding occurs at the pouring site, seriously affecting the normal construction of the concrete. In addition, when the temperature changes greatly, especially in autumn, the temperature is relatively high during the day and drops suddenly at night, and the release effect of the slump retention component in the admixture will be greatly affected, which will also cause the bleeding phenomenon of the fresh concrete not long after production, thus affecting the construction. It can be seen that the bleeding of concrete is closely related to the amount of slump retention component in the admixture. In actual production applications, more than 90% of the bleeding phenomena of concrete are caused by the relative over-dosage of the slump retention agent.

[0003] The workability of fresh concrete is an important index in daily concrete production. Insufficient workability is an important factor leading to pipe blockage, material return, and waste, causing huge waste and pollution to concrete production and the environment. Therefore, the product developed in this research is of great significance for solving such problems. Summary of the Invention

[0004] In order to solve the above-mentioned disadvantages and deficiencies existing in the prior art, the purpose of the present invention is to provide an anti-bleeding agent for concrete that can solve the bleeding problem of concrete, effectively improve the control level of the workability of fresh concrete, reduce the occurrence of adverse phenomena such as insufficient workability, material return and seasoning, and improve the construction efficiency of concrete, and a preparation method thereof.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is:

[0006] On the one hand, the present invention provides an anti-over-retarding concrete anti-bleeding agent, and the anti-bleeding agent comprises the following components by weight parts;

[0007]

[0008] Further, the water repellent agent for concrete bleeding prevention comprises the following components by weight:

[0009]

[0010] Further, the water repellent agent for concrete bleeding prevention comprises the following components by weight;

[0011]

[0012] Further, the naphthalene-based superplasticizer is a naphthalene sulfonic acid formaldehyde condensate with a sodium sulfate content of less than 3%.

[0013] Further, the emulsifier includes guar gum powder.

[0014] Further, the aluminum sulfate octadecahydrate is an industrial-grade aluminum sulfate octadecahydrate that is highly soluble in water.

[0015] Further, the naphthalene-based superplasticizer is a naphthalene sulfonate formaldehyde condensate.

[0016] On the other hand, the present invention also provides a preparation method for a water repellent agent for anti-over-retarding concrete bleeding prevention, and the preparation method includes the following steps:

[0017] Step 1) Weigh each component raw material of the water repellent agent according to the ratio described in Claim 1;

[0018] Step 2) Add two-sixths of water into a liquid mixer, start the liquid mixer, slowly add guar gum powder and hydroxypropyl methylcellulose ether into the liquid mixer, heat to 20 - 40 °C, the stirring time of the liquid mixer is 120 - 360 minutes, and let it stand for 60 - 120 minutes for standby after stirring;

[0019] Step 3) Add three-sixths of water into a mixer, start the mixer, slowly add sodium dodecyl sulfate, aluminum sulfate octadecahydrate, sodium thiosulfate, and naphthalene-based superplasticizer in sequence, mix them, stir for 30 - 120 minutes, then add the remaining amount of water, and mix evenly to obtain the finished product;

[0020] Step 4) Store the finished product obtained in Step 3 above in a finished product container, and the storage temperature is 6 °C - 40 °C.

[0021] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0022] 1), The water-repellent agent of the present invention comprises 4-6 parts of guar gum powder, 20-30 parts of aluminum sulfate octadecahydrate, 2-4 parts of sodium thiosulfate, 60-70 parts of naphthalene-based high-range water reducer, 0.5-1.5 parts of hydroxypropyl methyl cellulose ether, and 1-2 parts of sodium dodecyl sulfate. The water-repellent agent provided by the present invention can be used in the case where bleeding occurs in concrete construction due to excessive slump-keeping components in the admixture, affecting the normal pouring of concrete. The bleeding problem of fresh concrete can be solved by the water-repellent agent of the present invention, effectively improving the control level of the workability of fresh concrete.

[0023] 2), The preparation method of the present invention can give full play to the efficacy of each component through reasonable mixing, stirring, heating and other reactions of each component, so that the composition of the present invention can restore the bleeding concrete to the pourable level, and the preparation process is simple and easy to be widely promoted. Detailed implementation mode

[0024] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention is further illustrated by the following examples. Obviously, the following examples are only a part of the examples of the present invention, rather than all the examples; it should be understood that the embodiments of the present invention are only used to illustrate the technical effects of the present invention, rather than to limit the protection scope of the present invention.

[0025] On the one hand, the present invention provides an anti-over-slump concrete water-repellent agent, which comprises the following components by weight:

[0026]

[0027]

[0028] The operation of using the anti-over-slump concrete water-repellent agent of the present invention is as follows:

[0029] Before concrete pouring, if bleeding occurs, according to the severity of bleeding, add the water-repellent agent into the concrete mixer truck at 100g-200g / m 3 After adding, start the strong stirring of the mixer truck for 5-10 minutes. During the adding process, add it slowly to prevent over-dosage of the water-repellent agent. Over-dosage will cause the reduction of the fluidity of the concrete and over-drying. If the slump of the concrete decreases and the fluidity is insufficient due to excessive addition of the water-repellent agent, an appropriate amount of water reducer can be added again to increase the fluidity and make the concrete mixture meet the requirements of construction pouring.

[0030] The water repellent provided by the present invention is mainly aimed at sands, cements and admixtures (including fly ash, blast furnace slag powder, etc.) with relatively low water demand, while the corresponding admixtures of concrete use an excessive proportion of slump retention components, resulting in bleeding of the cast mixture, and this bleeding occurs within 2 hours after mixing. The problem of bleeding leading to unworkability can be solved by adding the water repellent of the present invention to restore the problematic concrete to a normal pourable level.

[0031] The water repellent of the present invention comprises the following components by weight: 5 - 6 parts of emulsifier, 25 - 30 parts of aluminum sulfate octadecahydrate, 3 - 4 parts of sodium thiosulfate, 65 - 70 parts of naphthalene series high - range water - reducer, 1 - 1.5 parts of hydroxypropyl methyl cellulose ether, 1.5 - 2 parts of sodium dodecyl sulfate.

[0032] Specifically, the water repellent of the present invention comprises the following components by weight: 5 parts of emulsifier, 25 parts of aluminum sulfate octadecahydrate, 3 parts of sodium thiosulfate, 65 parts of naphthalene series high - range water - reducer, 1 part of hydroxypropyl methyl cellulose ether, 1 part of sodium dodecyl sulfate.

[0033] The naphthalene series high - range water - reducer of the present invention is a naphthalene sulfonic acid - formaldehyde condensate with a sodium sulfate content of less than 3%.

[0034] Specifically, the emulsifier of the present invention comprises guar gum powder, also known as guar bean gum. Guar gum powder is mainly a natural galactomannan extracted from guar beans grown in India and is in powder form at normal temperature. The guar gum powder involved in the present invention can disperse and emulsify the bleeding caused by excessive slump - retaining agent in concrete, effectively solving the problems of sedimentation and separation of concrete.

[0035] The added aluminum sulfate octadecahydrate of the present invention is an industrial - grade aluminum sulfate octadecahydrate that is extremely soluble in water and is in powder form at normal temperature. The added aluminum sulfate octadecahydrate in the water repellent plays a role in partial coagulation acceleration, accelerating the chemical reaction between cement and water, reacting and consuming the excess secreted water, facilitating the restoration of the normal water demand of concrete, and ensuring the normal fluidity during construction.

[0036] The added sodium thiosulfate of the present invention, also known as sodium hyposulfite with the chemical formula Na2S2O3 and in powder form at normal temperature, plays the role of improving the wrapping property of concrete in the added sodium thiosulfate of the water repellent, wrapping more cement paste around the coarse aggregate, and reducing the occurrence of separation.

[0037] The naphthalene-based superplasticizer added to the water repellent of the present invention belongs to an anionic surfactant, and its main mechanism is surface adsorption to achieve water reduction. The naphthalene-based superplasticizer is a naphthalene sulfonate formaldehyde condensate, which is in powder form at room temperature. The polycarboxylate superplasticizer belongs to a polymer comb structure and is a non-ionic surfactant. Its main mechanism is electrostatic repulsion and steric hindrance to achieve water reduction. The mechanisms of the two are different. The present invention mainly aims at the application of polycarboxylate-based superplasticizers and slump retention agents. When the polycarboxylate-based admixture is applied and the naphthalene-based superplasticizer is added, due to the different mechanisms of the two, a repulsion phenomenon occurs, resulting in partial failure of the water reduction and slump retention performance of the polycarboxylate-based superplasticizer. And this kind of failure increases with the increase of the dosage of the naphthalene-based superplasticizer. Therefore, the naphthalene-based superplasticizer is added to the composition of the water repellent. The added naphthalene-based superplasticizer is relatively cheap, and the weight portion of the naphthalene-based superplasticizer is 60-70 parts, which accounts for the main component of the water repellent.

[0038] The hydroxypropyl methyl cellulose ether added in the present invention is of ordinary industrial grade and is in powder form at room temperature. Adding hydroxypropyl methyl cellulose ether to the water repellent can play the functions of defoaming, thickening and improving the wrapping property of concrete.

[0039] Sodium dodecyl sulfate in the present invention serves the purposes of air entrainment, increasing the fluidity of concrete and reducing the high viscosity caused by bleeding of concrete, and is used in combination with hydroxypropyl methyl cellulose ether. On the premise of ensuring that the air content meets the requirements and does not harm the strength, it improves the fluidity of concrete and enables the mixture to resume normal construction.

[0040] On the other hand, the present invention also provides a preparation method for a water repellent for anti-over-retarding type concrete, and the preparation method includes the following steps:

[0041] Step 1) Weigh each component raw material of the water repellent according to the ratio described in Claim 1;

[0042] Step 2) Add two-sixths of water into a liquid mixer, start the liquid mixer, slowly add guar gum powder and hydroxypropyl methyl cellulose ether into the liquid mixer, heat to 20-40 °C, and the stirring time of the liquid mixer is 120-360 minutes. After stirring, let it stand for 60-120 minutes for standby;

[0043] Step 3) Add three-sixths of water into a mixer, start the mixer, and slowly add sodium dodecyl sulfate, aluminum sulfate octadecahydrate, sodium thiosulfate and naphthalene-based superplasticizer in sequence. After mixing, stir for 30-120 minutes, and then add the remaining amount of water and mix evenly to obtain the finished product;

[0044] Step 4) Store the finished product obtained in Step 3 in a finished product container, and the storage temperature is 6 °C - 40 °C.

[0045] I. The present invention will be further described below in conjunction with three specific embodiments provided by the present invention:

[0046] In the specific embodiments of the present invention, the water-repellent agent of the present invention can be configured with the following components (unit: parts by weight), as specifically shown in Table 1 below:

[0047] 5 parts of guar gum powder, 25 parts of aluminum sulfate octadecahydrate, 3 parts of sodium thiosulfate, 65 parts of naphthalene-based high-range water reducer, 1.5 parts of hydroxypropyl methyl cellulose ether, 0.5 part of sodium dodecyl sulfate.

[0048] Raw material components Example 1 Example 2 Example 3 Guar gum powder 5 parts 5 parts 5 parts Aluminum sulfate octadecahydrate 25 parts 25 parts 25 parts Sodium thiosulfate 3 parts 3 parts 3 parts Naphthalene-based high-range water reducer 65 parts 65 parts 65 parts Hydroxypropyl methyl cellulose ether 1 part 0.5 part 1.5 parts Sodium dodecyl sulfate 1 part 1.5 parts 0.5 part

[0049] Table 1

[0050] According to the component weights provided in Examples 1 to 3 in Table 1 above, prepare the water-repellent agent according to the following specific method for preparing the water-repellent agent. The preparation method specifically includes the following steps:

[0051] Step 1) Weigh the raw materials of each component of the water-repellent agent according to the ratios described in Examples 1 to 3.

[0052] Step 2) Add two-sixths of water into the liquid mixer, start the liquid mixer, slowly add the guar gum powder and hydroxypropyl methyl cellulose ether into the liquid mixer, heat to 20 - 40 °C, the stirring time of the liquid mixer is 120 - 360 minutes, and let it stand for 60 - 120 minutes for standby after stirring.

[0053] Step 3) Add three-sixths of water into the mixer, start the mixer, and slowly add sodium dodecyl sulfate, aluminum sulfate octadecahydrate, sodium thiosulfate, and naphthalene-based high-range water reducer in sequence and mix them. Then stir for 30 - 120 minutes, and add the remaining amount of water and mix evenly to obtain the finished product.

[0054] Step 4) Store the finished product obtained in Step 3 above in a finished product container at a storage temperature of 6 °C - 40 °C.

[0055] II. Conduct slump test, spread test, and bleeding rate test on the water-repellent agent prepared in each of the above embodiments. The test conditions are as follows:

[0056] (Test 1) Test on the produced pumped C30 concrete

[0057] 1. Take the produced pumped C30 concrete. The mix proportion of C30 concrete is as follows:

[0058] Cement Fly ash Water Sand Crushed stone Admixture 280 80 168 852 1040 5.6

[0059] Table 2

[0060] 2. The results of the ex-factory inspection of the C30 concrete produced according to the above mix ratio are as follows: slump: 220 mm, spread: 610 mm, meeting the requirements for concrete ex-factory. However, after 1 hour of transportation and waiting, with the mixer truck continuously stirring without stopping and preparing to unload into the pump, it was found that the concrete had bleeding, could not be unloaded normally, and neither the slump nor the spread could be measured. Its bleeding rate reached 4.9%, and the water was severely separated from the mixture. After adding 150 g / m of the anti-bleeding agent prepared in Example 1 to the freshly mixed C30 mixture 3 , the bleeding rate decreased to 0.02%, and the slump and spread also recovered to 220 mm and 580 mm respectively. The measurement results are as follows:

[0061] Concrete performance Approximately 1 h after leaving the factory <![CDATA[Add 150 g / m 3 Water repellent]]> Bleeding rate 4.9％ 0.02％

[0062] Table 3

[0063] (Test 2) Test on the pumped C35 concrete produced

[0064] 1. Take the pumped C35 concrete produced. The mix ratio of the pumped C35 concrete is as follows:

[0065] Cement Ground granulated blast-furnace slag Fly ash Water Sand Crushed stone Admixture 300 80 70 168 790 1010 6.0

[0066] 2. The results of the ex-factory inspection of the C35 concrete produced according to the above mix ratio are as follows: slump: 230 mm, spread: 600 mm, meeting the requirements for concrete ex-factory. However, after 1 hour of transportation and waiting, with the mixer truck continuously stirring without stopping and preparing to unload into the pump, it was found that the concrete had bleeding, could not be unloaded normally, and neither the slump nor the spread could be measured. The bleeding rate of the C35 concrete was measured to be 5.2%. After adding 200 g / m of the anti-bleeding agent prepared in Example 2 to the C35 concrete 3 , the bleeding rate of the C35 concrete after adding the anti-bleeding agent was measured to have decreased to 0.1%, and the corresponding slump and spread were 230 mm and 580 mm respectively. The measurement results are as follows:

[0067] Concrete performance 1 h after leaving the factory <![CDATA[Add 200 g / m 3 Water repellent]]> Bleeding rate 5.2％ 0.1％

[0068] Table 4

[0069] (Test 3) Test on the pumped C50 concrete produced

[0070] 1. Take the pumped C50 concrete produced. The mix ratio of the C50 concrete is as follows:

[0071] Cement Ground granulated blast-furnace slag Fly ash Water Sand Crushed stone 380 80 40 167 720 1041

[0072] Table 5

[0073] 2. The factory inspection results of C50 concrete produced according to the above mix ratio showed that the slump was 220 mm and the expansion was 610 mm, which met the factory requirements for concrete. However, after 1 hour of transportation and waiting, the mixer truck did not stop stirring during the period. After unloading and preparing to enter the pump, it was found that the concrete had water seepage. The water seepage rate of C50 concrete was measured to be 4.2%. The slump and expansion could not be measured. Therefore, 200 g / m 2 prepared in Example 3 was added to the mixture. 3 After adding the anti-bleeding agent, the water seepage rate of C50 concrete was greatly reduced to 0.05%, and the slump and expansion were 220mm and 600mm respectively. The measurement results are as follows:

[0074] Concrete performance Anti-bleeding agent not added <![CDATA[Add 200 g / m 3 Water repellent]]> Bleeding rate 4.2％ 0.05％

[0075] Table 6

[0076] Based on the above embodiments and test results, it can be seen that the anti-bleeding agent of embodiments 1, 2 and 3 of the present invention can achieve the effects of reducing the water bleeding rate and restoring the slump and expansion.

[0077] The implementation methods of the present invention are not limited to the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. An anti-segregation water reducer for concrete with anti-over-retarding property, characterized in that: The anti-bleeding agent comprises the following components by weight parts; The naphthalene series superplasticizer is a naphthalene sulfonic acid formaldehyde condensate with a sodium sulfate content of less than 3%, and the emulsifier comprises guar gum powder.

2. The anti-segregation and slump-loss resistant water reducer for concrete according to claim 1, wherein: The anti-bleeding agent comprises the following components by weight parts:

3. The anti-segregation water reducer for anti-over-retarding concrete according to claim 1, characterized in that: The anti-bleeding agent comprises the following components by weight parts; 4. The anti-segregation and slump-loss resistant water reducer for concrete according to claim 1, characterized in that: The aluminum sulfate octadecahydrate is an industrial grade aluminum sulfate octadecahydrate that is highly soluble in water.

5. A preparation method for an anti-segregation and slump-loss resistant water reducer for concrete as described in claim 1, characterized in that: The preparation method comprises the following steps: Step 1) Weigh each component raw material of the anti-bleeding agent according to the ratio described in Claim 1; Step 2) Add two-sixths of water into a liquid mixer, start the liquid mixer, slowly add guar gum powder and hydroxypropyl methyl cellulose ether into the liquid mixer, heat to 20 - 40 °C, and the stirring time of the liquid mixer is 120 - 360 minutes. After stirring, let it stand for 60 - 120 minutes for standby; Step 3) Add three-sixths of water into a mixer, start the mixer, slowly add sodium dodecyl sulfate, aluminum sulfate octadecahydrate, sodium thiosulfate, and naphthalene series superplasticizer in sequence, mix them, stir for 30 - 120 minutes, then add the remaining amount of water, and mix evenly to obtain the finished product; Step 4) Store the finished product obtained in Step 3 above in a finished product container at a storage temperature of 6 °C - 40 °C.

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