A slurry-like admixture with reinforcing and slump-retaining functions, its preparation method and application

Abstract

This invention discloses a slurry-like admixture with reinforcing and slump-retaining functions, its preparation method, and its application. Using zeolite and water as main raw materials, and with the aid of a polymerization precursor, ammonium persulfate, and a grinding aid, this invention prepares a slurry-like admixture with reinforcing and slump-retaining functions through wet milling and in-situ polymerization. When the slurry-like admixture with reinforcing and slump-retaining functions prepared according to this invention is used in cement concrete at a dosage of 5%-10%, the fluidity of the cement paste increases by 30% after 1 hour, by 20% after 2 hours, and shows no loss after 3 hours; the compressive strength increases by 5% after 1 day, and does not decrease after 28 days.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a slurry-like admixture with reinforcing and slump-retaining functions, its preparation method, and its application. Background Technology

[0002] my country is currently in a crucial period of high-quality economic and social development, with major infrastructure projects and large-scale urbanization creating enormous demand for concrete materials, especially cement. According to the National Bureau of Statistics, China's cement production reached 2.12 billion tons in 2022. Cement production consumes significant amounts of energy and resources and releases large quantities of CO2 and dust. Therefore, reducing the amount of cement used in concrete while ensuring sufficient concrete strength is a major challenge for contemporary social and economic development.

[0003] Currently, the problem of significant slump loss in concrete is particularly serious in many construction projects across my country. Construction workers often add water directly to concrete to increase its flowability, which not only leads to a decrease in strength but also a sharp decline in durability, greatly increasing the risk of engineering problems and significantly shortening the service life of projects. To enhance the strength and flowability of concrete, researchers have developed various high-performance water-reducing agents and proposed the concept of slurry-like admixtures with water-reducing functions. Currently, my country's slurry-like admixtures focus on developing water-reducing functions, paying less attention to concrete segregation, bleeding, and slump loss. Therefore, developing an admixture with both strengthening and slump-retaining functions to improve concrete performance is essential. Summary of the Invention

[0004] In view of this, the present invention aims to provide a method for preparing a slurry admixture with reinforcing and slump-retaining functions, so as to solve the problem of poor reinforcing and slump-retaining effects of existing slurry admixtures.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] A method for preparing a slurry-like admixture with reinforcing and slump-retaining functions includes the following steps:

[0007] 1) By weight, 63-79 parts of zeolite, 0.7-1.3 parts of grinding aid, and 42-57 parts of water are mixed and then subjected to ultrafine treatment of the zeolite by wet grinding process to obtain ultrafine zeolite slurry.

[0008] 2) Add 5.9-8.3 parts of polymerization precursor to the ultrafine zeolite slurry, stir evenly, and then add 0.06-0.13 parts of ammonium persulfate. Under certain conditions, carry out in-situ polymerization reaction to obtain a slurry admixture with reinforcing and slump-retaining functions.

[0009] Optionally, the grinding aid in step 1) is a mixture of sodium tripolyphosphate and sodium hexametaphosphate, and the mass ratio of sodium tripolyphosphate to sodium hexametaphosphate is (0.6-1.2):(1.1-1.5).

[0010] Optionally, the wet grinding speed in step 1) is 23-29 rpm and the wet grinding time is 30-45 min.

[0011] Optionally, the grinding medium in the wet grinding process described in step 1) is a zirconia grinding media; the mass of the zirconia grinding media is 3 times the mass of the zeolite, and the gradation of the zirconia grinding media is 10mm∶8mm∶5mm∶3mm=1∶4∶4∶1.

[0012] Optionally, the median particle size of the ultrafine zeolite slurry described in step 1) is 6-10 μm, and the water content is 50%-70%.

[0013] Optionally, the polymerization precursor in step 2) is a mixture of acrylic acid, hydroxyethyl acrylate, and methyl allyl polyoxyethylene ether, and the mass ratio of acrylic acid, hydroxyethyl acrylate, and methyl allyl polyoxyethylene ether is (0.3-0.4):(0.6-0.8):10.

[0014] Optionally, the reaction temperature of the in-situ polymerization reaction in step 2) is 50-60℃, and the reaction time is 3-4h.

[0015] A second objective of the present invention is to provide a slurry admixture with reinforcing and slump-retaining functions, which is prepared by the above-described method.

[0016] A third objective of this invention is to provide an application of a slurry admixture with reinforcing and slump-retaining functions in cement concrete, wherein the dosage of the slurry admixture with reinforcing and slump-retaining functions is 5%-10% of the amount of cementitious materials in the cement concrete.

[0017] Preparation mechanism of the present invention:

[0018] This invention uses zeolite and water as main raw materials, and prepares a slurry-like admixture with strengthening and slump-retaining functions through wet milling and in-situ polymerization under the action of a polymerization precursor, ammonium persulfate, and grinding aid. The wet milling process introduces water molecules during grinding, reducing particle surface energy and preventing particle agglomeration that may occur during conventional milling. Ultrafine treatment of the zeolite yields zeolite particles with a smaller particle size than those produced by conventional milling. This facilitates secondary reactions between the active silicon and active aluminum embedded in the zeolite and the Ca(OH)2 provided during cement hydration, generating more hydration products and improving strength. Furthermore, the polymerization precursor interacts with the initiator to undergo an in-situ polymerization reaction, synthesizing a slow-release slump-retaining agent with ester groups. Due to the porous nature and excellent adsorption properties of zeolite, using ultrafine zeolite as a carrier to adsorb the slump-retaining agent generated by the in-situ polymerization reaction can also achieve the purpose of slow-release slump retention. The synergistic slow-release effect of the two enables the cement slurry to maintain good fluidity in the later stage of hydration, meeting the needs of ultra-long distance and ultra-high height pumping construction.

[0019] Compared with existing technologies, the slurry admixture with reinforcing and slump-retaining functions described in this invention has the following advantages:

[0020] 1. The slurry admixture with reinforcing and slump-retaining functions of the present invention is prepared by in-situ polymerization, which effectively simplifies the preparation process and reduces production costs. Moreover, it can partially replace cement paste and be directly used in the production of building materials. When it is used in cement concrete at a dosage of 5%-10%, the fluidity of cement paste increases by 30% in 1 hour, 20% in 2 hours, and there is no loss in 3 hours; the compressive strength increases by 5% in 1 day and does not decrease in 28 days. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions and effects of the present invention, several embodiments will be provided below. Obviously, the following description is only an embodiment and does not limit the scope of protection of the present invention.

[0022] Table 1 shows the proportions of each component in the slurry admixture with reinforcing and slump-retaining functions of Examples 1-6 of the present invention, as well as the performance parameters during the preparation process.

[0023] Table 1

[0024]

[0025] The slurry-like admixtures with reinforcing and slump-retaining functions in Examples 1-6 were specifically prepared by the following methods:

[0026] 1) Weigh zeolite, grinding aid, and water according to the raw material ratio in Table 1, controlling the error to be accurate to ±0.01g, and add them and a certain mass of grinding media into a tube ball mill. Start the ball mill at 25 rpm and wet grind for 35 min to ultrafine the zeolite and obtain ultrafine zeolite slurry. The median particle size of the ultrafine zeolite slurry in Examples 1-6 is shown in Table 1.

[0027] 2) Take out the ultrafine zeolite slurry from step 1), and add the polymerization precursor to the zeolite slurry according to the raw material ratio in Table 1. Stir evenly, then add ammonium persulfate as an initiator, heat to 50°C, and continue stirring for 3 hours to carry out in-situ polymerization reaction to obtain a slurry-like admixture with reinforcing and slump-retaining functions.

[0028] The slurry admixtures with reinforcing and slump-retaining functions of Examples 1-6 of the present invention are applied to cement concrete, and the dosage is 5%-10% of the amount of cementitious materials in the cement concrete.

[0029] The fluidity of cement paste containing the reinforcing and slump-retaining slurry admixtures of Examples 1-6 of this invention was tested in accordance with the standard GB / T 8076-2008 "Concrete Admixtures". The test results are shown in Table 2.

[0030] Table 2

[0031]

[0032] As shown in Table 2, adding 5%-10% of the slurry admixture of this invention with reinforcing and slump-retaining functions to cement concrete results in a 30%-37% increase in fluidity after 1 hour and a 20%-26% increase after 2 hours. This indicates that the slurry admixture of this invention with reinforcing and slump-retaining functions enhances fluidity and reduces slump loss in the early stages. Furthermore, there is no loss in fluidity after 3 hours, indicating that the slurry admixture of this invention with reinforcing and slump-retaining functions has no negative impact on the later-stage fluidity of the cement paste.

[0033] The strength of cement paste containing the reinforcing and slump-retaining slurry admixtures of Examples 1-6 of this invention was tested in accordance with the standard GB / T 8076-2008 "Concrete Admixtures". The test results are shown in Table 3.

[0034] Table 3

[0035]

[0036] As shown in Table 3, adding 5%-10% of the reinforcing and slump-retaining paste admixture of the present invention to cement concrete increases the 1-day compressive strength by 5%-9%, indicating that the reinforcing and slump-retaining paste admixture of the present invention enhances early strength. Furthermore, there is no loss of 28-day strength, indicating that the reinforcing and slump-retaining paste admixture of the present invention has no adverse effect on the later-stage strength of the cement paste.

[0037] The above are merely preferred embodiments of the present invention and are 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 within the protection scope of the present invention.

Claims

1. A method for producing a slurry blend having enhanced slump retention and slump recovery, characterized by, Includes the following steps: 1) By weight, 63-79 parts of zeolite, 0.7-1.3 parts of grinding aid, and 42-57 parts of water are mixed and then subjected to ultrafine treatment of the zeolite by wet grinding process to obtain ultrafine zeolite slurry. 2) Add 5.9-8.3 parts of polymerization precursor to the ultrafine zeolite slurry, stir evenly, and then add 0.06-0.13 parts of ammonium persulfate. Under certain conditions, carry out in-situ polymerization reaction to obtain a slurry admixture with reinforcing and slump-retaining functions.

2. The method of producing a paste-like admixture having a function of enhancing and maintaining slump according to claim 1, wherein The grinding aid mentioned in step 1) is a mixture of sodium tripolyphosphate and sodium hexametaphosphate, and the mass ratio of sodium tripolyphosphate to sodium hexametaphosphate is (0.6-1.2):(1.1-1.5).

3. The method of producing a paste-like admixture having a function of enhancing and maintaining slump according to claim 1, wherein The wet grinding speed in step 1) is 23-29 rpm, and the wet grinding time is 30-45 min.

4. The method of producing a paste-like admixture having a function of enhancing and maintaining slump according to claim 1, wherein The grinding medium in the wet grinding process described in step 1) is a zirconia grinding media; the mass of the zirconia grinding media is 3 times the mass of the zeolite, and the gradation of the zirconia grinding media is 10mm∶8mm∶5mm∶3mm=1∶4∶4∶1.

5. The method of producing a paste-like admixture having a function of enhancing and maintaining slump according to claim 1, wherein The median particle size of the ultrafine zeolite slurry mentioned in step 1) is 6-10 μm, and the water content is 50%-70%.

6. The method of producing a paste-like admixture having a function of enhancing and maintaining slump according to claim 1, wherein The polymerization precursor in step 2) is a mixture of acrylic acid, hydroxyethyl acrylate, and methyl allyl polyoxyethylene ether, and the mass ratio of acrylic acid, hydroxyethyl acrylate, and methyl allyl polyoxyethylene ether is (0.3-0.4):(0.6-0.8):

10.

7. The method of producing a paste-like admixture having a function of enhancing and maintaining slump according to claim 1, wherein The in-situ polymerization reaction described in step 2) has a reaction temperature of 50-60℃ and a reaction time of 3-4h.

8. A paste-like admixture having a function of enhancing and maintaining slump, characterized by comprising: It is prepared by the method for preparing the slurry admixture with reinforcing and slump-retaining functions according to any one of claims 1 to 7.

9. Use of the slurry blend with enhanced slump retention function according to claim 8 in cement concrete, characterized in that, The amount of the slurry admixture with reinforcing and slump-retaining functions is 5%-10% of the amount of cementitious materials in the cement concrete.

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