An admixture for improving the impermeability of marine concrete and a preparation method thereof

Abstract

The application discloses an admixture for improving the impermeability of marine concrete and a preparation method thereof, and belongs to the technical field of concrete admixtures. Components of the admixture for improving the impermeability of marine concrete include, by weight fraction, 100 parts of tackifying modified lignocellulose nanofiber, 10-20 parts of sodium dodecyl benzene sulfonate, 10-15 parts of high-efficiency water reducing agent and 100-150 parts of silica ash. The tackifying modified lignocellulose nanofiber and the silica ash are used as main raw materials, and the water reducing agent and the sodium dodecyl benzene sulfonate for improving workability are combined, so that the impermeability of the marine concrete can be improved, the compactness of the marine concrete can be improved by reducing the water-cement ratio, and the mechanical strength and the impermeability of the marine concrete can be improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of concrete admixtures, and particularly relates to an admixture for improving the impermeability of marine concrete and a preparation method thereof. BACKGROUND

[0002] The concrete used in marine engineering is also called marine concrete. Marine engineering includes coastal engineering and offshore engineering. The concrete used in structures subjected to the influence of seawater and structures subjected to the influence of seawater on shore is marine concrete. Marine concrete is often or periodically in contact with seawater, and high-concentration corrosion ions Mg 2+ , SO4 2- , Cl - in seawater can easily cause problems such as internal damage, cementing force degradation, and steel corrosion of marine concrete.

[0003] How to improve the durability of marine concrete depends on how to improve the impermeability of marine concrete to reduce the entry of corrosion ions into the interior of marine concrete, thereby avoiding the corrosion of steel by corrosion ions and the reaction of corrosion ions with calcium hydroxide in the interior of marine concrete to generate substances such as ettringite that can damage the internal structure of marine concrete.

[0004] Currently, there are two methods for treating the impermeability of marine concrete. One is to add an impermeability agent, and the other is to apply an impermeability coating on the surface of marine concrete. However, the impermeability coating is easy to fall off and lose the impermeability effect. The current impermeability agent has problems such as poor impermeability effect and complex formula. SUMMARY

[0005] The purpose of the present application is to provide an admixture for improving the impermeability of marine concrete and a preparation method thereof. By using tackiness-modified lignocellulose nanofiber and silica fume as main raw materials, in combination with water reducing agent and sodium dodecyl benzene sulfonate for improving workability, the impermeability of marine concrete can be improved, the compactness of marine concrete can be improved by reducing the water-cement ratio, and the mechanical strength and impermeability of marine concrete can be improved.

[0006] To achieve the above purpose, the present application provides the following technical scheme:

[0007] One of the technical schemes of the present application is to provide an admixture for improving the impermeability of marine concrete, which comprises, by weight, 100 parts of tackiness-modified lignocellulose nanofiber, 10-20 parts of sodium dodecyl benzene sulfonate, 10-15 parts of high-efficiency water reducing agent, and 100-150 parts of silica fume; the water-reducing rate of the high-efficiency water reducing agent is >40%.

[0008] Preferably, the tackiness-modified lignocellulose nanofiber is acrylamide-grafted lignocellulose nanofiber.

[0009] Preferably, the preparation step of the acrylamide grafted lignocellulose nanofiber comprises: mixing acrylamide, sodium p-styrenesulfonate and lignocellulose nanofiber with water, then adding initiator and crosslinking agent, drying after reaction, thereby obtaining the acrylamide grafted lignocellulose nanofiber.

[0010] Preferably, the mass ratio of the acrylamide to the lignocellulose nanofiber is 1:10; the mass ratio of the acrylamide to the sodium p-styrenesulfonate is 1:1; the addition amount of the initiator is 0.8-1.2% of the mass of the acrylamide; and the addition amount of the crosslinking agent is 0.8-1.2% of the mass of the acrylamide.

[0011] Preferably, the initiator is ammonium persulfate; and the crosslinking agent is N,N'-methylene bisacrylamide.

[0012] Preferably, the high-efficiency water-reducing agent is a polycarboxylic acid high-efficiency water-reducing agent.

[0013] Preferably, the specific surface area of the silica ash is 20-25 m 2 / g.

[0014] The second technical solution of the present application provides a preparation method of the above-mentioned admixture for improving the impermeability of marine concrete, comprising the following steps: uniformly mixing the tackifying modified lignocellulose nanofiber, sodium dodecyl benzene sulfonate and silica ash, separately packaging the high-efficiency water-reducing agent, and combining to obtain the admixture for improving the impermeability of marine concrete.

[0015] The third technical solution of the present application provides an application of the above-mentioned admixture for improving the impermeability of marine concrete in the preparation of marine concrete.

[0016] Preferably, the addition amount of the admixture for improving the impermeability of marine concrete is 10-15% of the mass of the cementitious material in the marine concrete.

[0017] The present application has the following beneficial technical effects:

[0018] The raw materials of the admixture formula for improving the impermeability of marine concrete provided by the application include tackifying modified lignocellulose nanofiber, sodium dodecyl benzene sulfonate, superplasticizer and silica ash. The selected tackifying modified lignocellulose nanofiber can be filled in the cracks between the cementitious materials and aggregates of the marine concrete, effectively bridging the cementitious materials and aggregates, at the same time, the tackifying modified lignocellulose nanofiber filled in the cracks can serve as nucleation sites of the hydration products, the high specific surface area silica ash added can serve as raw materials of the hydration products, in addition, the high strength characteristics of the lignocellulose can improve the strength of the hydration products, and the water absorption and swelling characteristics can enable the lignocellulose to better fill in the cracks of the concrete, greatly enhancing the impermeability of the marine concrete. The superplasticizer in the formula can greatly reduce the water-cement ratio, thereby improving the density, strength and impermeability of the marine concrete, and the sodium dodecyl benzene sulfonate can overcome the problem of reduced workability caused by the low water-cement ratio.

[0019] The raw materials of the admixture formula for improving the impermeability of marine concrete provided by the application can complement each other, as a new impermeability additive for marine concrete, the admixture formula can greatly improve the impermeability of the prepared marine concrete, avoid the marine concrete from being eroded by the erosion ions in seawater, improve the durability of the marine concrete and prolong the service life of the marine concrete.

[0020] The raw materials of the admixture formula for improving the impermeability of marine concrete provided by the application are simple in preparation conditions and have good popularization and application prospects. DETAILED DESCRIPTION

[0021] The various illustrative embodiments of the application are now described in detail. The detailed description is not intended to limit the application to the particular illustrative embodiments described, but rather just to explain certain aspects of the application. It should be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0022] In addition, for numerical ranges of the present application, it is understood that every numerical middle point between the upper and lower limits of that range is also specifically disclosed. Each smaller range between any stated value or between any stated lower limit, and any stated upper limit of the range is also encompassed. The upper and lower limits of these smaller ranges can independently be included or excluded in the range.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. Any and all

[0024] As used herein, "include," "includes" or "comprise," "comprises" or "comprising" are open-ended and mean "including but not limited to"; "parts" refer to "parts by weight" unless otherwise specified.

[0025] The application provides an additive for improving the impermeability of marine concrete, which comprises, by weight parts, 100 parts of tackiness-modified lignocellulose nanofiber, 10-20 parts of sodium dodecyl benzene sulfonate, 10-15 parts of high-efficiency water reducing agent, and 100-150 parts of silica ash; the water-reducing rate of the high-efficiency water reducing agent is >40%.

[0026] Further, the tackiness-modified lignocellulose nanofiber is acrylamide-grafted lignocellulose nanofiber.

[0027] Further, the preparation steps of the acrylamide-grafted lignocellulose nanofiber comprise: mixing acrylamide, sodium p-styrenesulfonate and lignocellulose nanofiber with water, then adding an initiator and a crosslinking agent, and drying after reaction to obtain the acrylamide-grafted lignocellulose nanofiber.

[0028] In the formula, the mass ratio of the acrylamide to the lignocellulose nanofiber is 1:10; the mass ratio of the acrylamide to the sodium p-styrenesulfonate is 1:1; the initiator is added in an amount of 0.8-1.2% of the mass of the acrylamide; the crosslinking agent is added in an amount of 0.8-1.2% of the mass of the acrylamide; the initiator is ammonium persulfate; and the crosslinking agent is N,N'-methylenebisacrylamide.

[0029] Further, the high-efficiency water reducing agent is a polycarboxylic acid high-efficiency water reducing agent.

[0030] The application selects a polycarboxylic acid high-efficiency water reducing agent with a water-reducing rate >40% as an additive, which can greatly reduce the water-cement ratio of marine concrete and further improve the strength of marine concrete.

[0031] Further, the specific surface area of the silica ash is 20-25 m 2 / g.

[0032] The application further provides a preparation method of the additive for improving the impermeability of marine concrete, which comprises the following steps: uniformly mixing the tackiness-modified lignocellulose nanofiber, the sodium dodecyl benzene sulfonate and the silica ash, separately packaging the high-efficiency water reducing agent, and combining to obtain the additive for improving the impermeability of marine concrete.

[0033] The application further provides application of the additive for improving the impermeability of marine concrete in the preparation of marine concrete; and the additive for improving the impermeability of marine concrete is added in an amount of 10-15% of the mass of cementitious materials in the marine concrete.

[0034] The specific embodiments provided by the present application are as follows:

[0035] The acrylamide grafted wood cellulose nanofiber used in the embodiments of the present application is prepared by the following steps:

[0036] 1 part of wood cellulose nanofiber is dispersed in 10 parts of water, 0.1 part of acrylamide and 0.1 part of sodium styrene sulfonate are added, and after uniform stirring, 0.001 part of ammonium persulfate and 0.0012 part of N,N'-methylene bisacrylamide are added, and the stirring is continued for 1 h, and then the moisture is removed to obtain the acrylamide grafted wood cellulose nanofiber.

[0037] The preparation steps of the acrylamide grafted nanoglass fiber used in the comparative example of the present application are as follows:

[0038] Compared with the preparation method of the acrylamide grafted wood cellulose nanofiber, the only difference is that the wood cellulose nanofiber is replaced by equal mass of nanoglass fiber.

[0039] The preparation steps of the acrylamide grafted polyurethane nanofiber used in the comparative example of the present application are as follows:

[0040] Compared with the preparation method of the acrylamide grafted wood cellulose nanofiber, the only difference is that the wood cellulose nanofiber is replaced by equal mass of polyurethane nanofiber.

[0041] Example 1

[0042] Preparation of the admixture for improving the impermeability of marine concrete:

[0043] Take 100 parts of the tackiness-modified wood cellulose nanofiber, 10 parts of sodium dodecyl benzene sulfonate and 100 parts of silica ash, mix uniformly, separately package 10 parts of polycarboxylic acid superplasticizer (water-reducing rate > 40%), and then combine to obtain the admixture for improving the impermeability of marine concrete.

[0044] Example 2

[0045] Preparation of the admixture for improving the impermeability of marine concrete:

[0046] Take 100 parts of the tackiness-modified wood cellulose nanofiber, 20 parts of sodium dodecyl benzene sulfonate and 100 parts of silica ash, mix uniformly, separately package 10 parts of polycarboxylic acid superplasticizer (water-reducing rate > 40%), and then combine to obtain the admixture for improving the impermeability of marine concrete.

[0047] Example 3

[0048] Preparation of the admixture for improving the impermeability of marine concrete:

[0049] Take 100 parts of tackifying modified lignocellulose nanofiber, 10 parts of sodium dodecyl benzene sulfonate and 130 parts of silica ash, mix uniformly, and separately package 15 parts of polycarboxylic acid superplasticizer (water-reducing rate > 40%) to obtain the admixture for improving the impermeability of marine concrete.

[0050] Comparative Example 1

[0051] Preparation of the admixture for improving the impermeability of marine concrete:

[0052] Compared with Example 1, the only difference is that the tackifying modified lignocellulose nanofiber is replaced by equal quality of acrylamide grafted nanoglass fiber.

[0053] Comparative Example 2

[0054] Preparation of the admixture for improving the impermeability of marine concrete:

[0055] Compared with Example 1, the only difference is that the tackifying modified lignocellulose nanofiber is replaced by equal quality of acrylamide grafted polyurethane nanofiber.

[0056] Use of the admixtures prepared in Examples 1-3 and Comparative Examples 1-2 to prepare marine concrete:

[0057] The specific formula of the marine concrete is: ordinary Portland cement (P.O 42.5) 300 parts, first-class fly ash 100 parts, river sand (particle size range 0.2-4.5 mm) 700 parts, 5-25 mm graded gravel 1000 parts, each group of admixture 40 parts and water 80 parts.

[0058] The preparation steps are: first, mix all the solid components uniformly, then mix the polycarboxylic acid superplasticizer in the water and the admixture, and then add them to the solid components, and after stirring, the marine concrete is obtained.

[0059] Determine the properties of the prepared marine concrete, and the determination results are shown in Table 1.

[0060] Table 1 Marine concrete performance

[0061]

[0062] As can be seen from Table 1, compared with nanoglass fiber and polyurethane nanofiber without expansion performance, lignocellulose nanofiber can significantly enhance the impermeability when used in the impermeability agent, and also helps the mechanical properties of marine concrete. The excellent impermeability of the marine concrete prepared in Examples 1-3 shows that the impermeability agent provided by the present application helps to improve the service life of marine concrete.

[0063] The above described embodiments are only to illustrate the preferred modes of the present application, and are not intended to limit the scope of the present application. Any modification and improvement made by those skilled in the art to the technical solutions of the present application without departing from the design spirit of the present application shall fall within the protection scope of the present application as defined by the claims.

Claims

1. An admixture for improving the impermeability of marine concrete, characterized in that, By weight, the components include: 100 parts of thickening modified lignocellulose nanofibers, 10-20 parts of sodium dodecylbenzenesulfonate, 10-15 parts of high-efficiency water-reducing agent, and 100-150 parts of silica fume; the water reduction rate of the high-efficiency water-reducing agent is >40%; The thickening and modified lignocellulose nanofibers are acrylamide-grafted lignocellulose nanofibers. The preparation steps of the acrylamide-grafted lignocellulose nanofibers include: mixing acrylamide, sodium p-styrene sulfonate and lignocellulose nanofibers with water, then adding an initiator and a crosslinking agent, and drying after reaction to obtain the acrylamide-grafted lignocellulose nanofibers. The mass ratio of acrylamide to lignocellulose nanofibers is 1:10; the mass ratio of acrylamide to sodium p-styrene sulfonate is 1:1; the amount of initiator added is 0.8-1.2% of the mass of acrylamide; and the amount of crosslinking agent added is 0.8-1.2% of the mass of acrylamide.

2. The admixture for improving the impermeability of marine concrete according to claim 1, characterized in that, The initiator is ammonium persulfate; the crosslinking agent is N,N'-methylenebisacrylamide.

3. The admixture for improving the impermeability of marine concrete according to claim 1, characterized in that, The high-efficiency water-reducing agent is a polycarboxylate high-efficiency water-reducing agent.

4. The admixture for improving the impermeability of marine concrete according to claim 1, characterized in that, The specific surface area of ​​the silica fume is 20-25 m². 2 / g.

5. A method for preparing an admixture for improving the impermeability of marine concrete as described in any one of claims 1 to 4, characterized in that, Includes the following steps: The thickening and modified lignocellulose nanofibers, sodium dodecylbenzenesulfonate, and silica fume are mixed evenly, and the high-efficiency water-reducing agent is packaged separately. The combination is the admixture for improving the impermeability of marine concrete.

6. The application of the admixture for improving the impermeability of marine concrete as described in any one of claims 1 to 4 in the preparation of marine concrete.

7. The application according to claim 6, characterized in that, The amount of the admixture used to improve the impermeability of marine concrete is 10-15% of the mass of the cementitious materials in the marine concrete.

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