Super slow-setting concrete and preparation method thereof

Abstract

The present application relates to the field of concrete, and more specifically, it relates to a super slow setting concrete and a preparation method thereof. A super slow setting concrete, according to mass fraction, includes the following raw materials: 280-300 parts of cement, 160-175 parts of water, 1000-1200 parts of coarse aggregate, 700-900 parts of fine aggregate, 1-4 parts of Wenlun glue, 0.8-2.5 parts of ethylenediaminetetramethylenephosphonic acid, 5-15 parts of coconut husk, 80-120 parts of admixture; its preparation method is: Wenlun glue, ethylenediaminetetramethylenephosphonic acid, coconut husk and 10-20% of water are mixed to obtain a premix; cement, remaining water, and admixture are mixed until uniform; then the premix is ​​continued to be added to mix until uniform; then coarse aggregate and fine aggregate are continued to be mixed until uniform to obtain a finished product. The present application has the advantage of delaying the setting time of concrete.

Description

Technical Field

[0001] The present application relates to the field of concrete, and more specifically, to a super slow-setting concrete and a preparation method thereof. Background Art

[0002] With the development of society and the needs of large-scale projects, the application scope and fields of concrete are becoming wider and wider, and accordingly, the requirements for concrete performance are also becoming higher and higher.

[0003] In some large-scale construction projects such as bridges, in order to improve the bearing capacity of a single pile, the length of the pile is often increased and the width of the pile is expanded. This directly leads to a large amount of concrete required for the single pile and a longer pouring time. If during the pouring process, the lower layer has solidified but the upper layer has not yet been poured, it will cause problems such as broken piles, affecting the quality of the single pile. Therefore, there is still room for improvement. Summary of the invention

[0004] In order to delay the setting time of concrete, the present application provides a super slow setting concrete and a preparation method thereof.

[0005] In the first aspect, the present application provides a super slow setting concrete, which adopts the following technical solution:

[0006] A super slow setting concrete comprises the following raw materials in parts by mass: 280-300 parts of cement, 160-175 parts of water, 1000-1200 parts of coarse aggregate, 700-900 parts of fine aggregate, 1-4 parts of warm wheel glue, 0.8-2.5 parts of ethylenediaminetetramethylenephosphonic acid, 5-15 parts of coconut bran and 80-120 parts of admixture.

[0007] By adopting the above technical scheme, with the cooperation of Wenlun glue, ethylenediaminetetramethylenephosphonic acid and coconut bran, a uniform adsorption layer is quickly formed on the surface of cement particles, covering the surface of cement particles, thereby effectively hindering the combination of cement particles with free water, making the hydration reaction rate very slow, thereby playing a retarding effect. In addition, the use of the three greatly improves the hydrophilic effect, and a large number of water molecules are attracted to the outside of the adsorption layer to form a dense water film. Since the water molecules are attracted, even if the hydration reaction is slow, a large number of water molecules will not precipitate to cause serious water bleeding. The attracted water molecules can react with the cement particles in a timely and rapid manner in the subsequent reaction, and fully undergo hydration reaction, thereby giving the concrete a higher compressive strength.

[0008] In addition, due to the formation of water film, the flocculation structure of cement particles will be destroyed, releasing free water, which has a certain water reduction effect; moreover, it can also make the water and cement particles in the system fully dispersed and improve fluidity.

[0009] Preferably, the mass ratio of the Wenlun rubber, ethylenediaminetetramethylenephosphonic acid and coconut bran is (1.5-3.0):(1-2):(8-13).

[0010] By adopting the above technical scheme, while limiting the usage of Wenlun glue, ethylenediaminetetramethylenephosphonic acid and coconut bran, and further limiting the usage ratio between the three, it is beneficial to form a more uniform adsorption layer, and it is also beneficial to improve the hydrophilic effect to form a thicker water film, thereby increasing the retarding time of concrete and the subsequent compressive strength.

[0011] Preferably, the coconut bran includes modified coconut bran;

[0012] The preparation method of modified coconut husk comprises the following steps:

[0013] Take ammonia water with a mass concentration of 10-15%, soak ordinary coconut bran in the ammonia water for 6-12 hours, and then take it out to obtain modified coconut bran; during the soaking, the mass ratio of ordinary coconut bran to ammonia water is 1: (3-5).

[0014] By adopting the above technical solution, coconut bran is modified so that hemicellulose and lignin in the coconut bran are dissolved and decomposed into monosaccharides. The modified coconut bran reacts with calcium ions to generate calcium saccharate in the alkaline system of concrete reaction, under the cooperation of Wenlun glue and ethylenediaminetetramethylenephosphonic acid, so that the cement hydration reaction process becomes slow, thereby extending the retarding time.

[0015] In addition, the use of modified coconut bran can make it easier for the adsorption layer to cover the surface of cement particles in a large area, so that the surfaces of cement particles and cement hydration particles carry the same charge, thereby repelling each other, thereby improving the dispersion effect, achieving better water reduction effect and improving strength.

[0016] Preferably, the coconut bran is composed of modified coconut bran and ordinary coconut bran, and the mass ratio of modified coconut bran to ordinary coconut bran is 1:(0.3-0.7).

[0017] Ordinary coconut bran has a rich pore structure. When mixed with Wenlun rubber and EDTA, some of the raw materials will be adsorbed into the pores and are not easy to fall off, thus achieving a more sufficient mixing effect and forming a denser and more uniform adsorption layer.

[0018] By adopting the above technical scheme, the input ratio of modified coconut bran and ordinary coconut bran is further limited, which can ensure sufficient mixing between the raw materials and ensure a good dispersion effect.

[0019] Preferably, the super slow setting concrete further comprises 3-6 parts by weight of a polycarboxylic acid-based water reducer.

[0020] Adding polycarboxylic acid water reducer into the system can further reduce the amount of water required for super slow setting concrete, thereby improving its strength.

[0021] Moreover, with the cooperation of Wenlun glue, ethylenediaminetetramethylenephosphonic acid, coconut bran and polycarboxylic acid water reducer, the electrostatic repulsion when adsorbed on the surface of cement particles can be further enhanced, the mechanical strength of the water film can be strengthened, and it is not easy to break in a short time.

[0022] Preferably, the admixture includes a mixture of one or more of steel slag powder, slag powder and fly ash.

[0023] Preferably, the admixture is steel slag powder, slag powder and fly ash, and the mass ratio of steel slag powder, slag powder and fly ash is 1:(1.5-2):(2-3).

[0024] By adopting the above technical scheme, the admixtures are further limited to specific types and specific proportions, which can give full play to the hydration activity of steel slag powder, slag powder and fly ash, and help reduce the required water consumption, thereby helping to improve the strength of concrete.

[0025] In a second aspect, the present application provides a method for preparing super slow-setting concrete, which adopts the following technical solution:

[0026] A method for preparing super slow-setting concrete comprises the following steps:

[0027] Mixing Wenlun rubber, ethylenediaminetetramethylenephosphonic acid, coconut bran and 10-20% water to obtain a premix;

[0028] Mix cement, remaining water and admixtures until uniform;

[0029] Continue to add the premixed solution and mix until uniform;

[0030] Then continue to add coarse aggregate and fine aggregate and mix until uniform to obtain the finished product.

[0031] Preferably, when the Wenlun rubber, ethylenediaminetetramethylenephosphonic acid, coconut bran and 10-20% of water are mixed, the mixing is carried out at 55-65°C.

[0032] Preferably, when the premix is ​​added, 3-6 parts by mass of a polycarboxylic acid water reducer is also added.

[0033] By adopting the above technical solution, the Wenlun rubber, ethylenediaminetetramethylenephosphonic acid and coconut bran are mixed in advance and set to be mixed at a specific temperature, which is conducive to better dispersion and mixing effects in the system later.

[0034] In summary, this application has the following beneficial effects:

[0035] 1. With the cooperation of Wenlun glue, ethylenediaminetetramethylenephosphonic acid and coconut bran, a uniform adsorption layer is quickly formed on the surface of cement particles, covering the surface of cement particles, thereby effectively hindering the combination of cement particles and free water, making the hydration reaction speed very slow, thus playing a retarding effect.

[0036] 2. The use of the three greatly improves the hydrophilic effect. A large number of water molecules are attracted to the outside of the adsorption layer to form a dense water film. Since the water molecules are attracted, even if the hydration reaction is slow, a large number of water molecules will not precipitate to cause serious water bleeding. The attracted water molecules can react with cement particles in a timely and rapid manner in the subsequent reaction, fully react with hydration, and thus give the concrete a higher compressive strength.

[0037] 3. Further limit the input ratio of modified coconut bran and ordinary coconut bran, which can ensure sufficient mixing between the raw materials and ensure good dispersion effect. DETAILED DESCRIPTION

[0038] The present application is further described in detail below with reference to the embodiments.

[0039] The raw materials used in the following examples and comparative examples are all commercially available products.

[0040] Preparation Example

[0041] Preparation Example 1

[0042] A modified coconut bran, the preparation method of which comprises the following steps:

[0043] Step 1): Dry the ordinary coconut bran, grind it into powder and set aside.

[0044] Step 2): Take ammonia water with a mass concentration of 10%, place the common coconut bran obtained in step 1) in the ammonia water, and let it stand and soak for 12 hours.

[0045] When soaking, the mass ratio of coconut bran to ammonia water is 1:3.

[0046] Step 3) taking out the soaked common coconut bran, filtering and drying to obtain the modified coconut bran.

[0047] Preparation Example 2

[0048] A modified coconut bran, which is different from Preparation Example 1 in that:

[0049] In step 2), the mass concentration of ammonia water is 15%, the soaking time is 6 hours, and the mass ratio of ordinary coconut bran to ammonia water is 1:5.

[0050] Example

[0051] Example 1

[0052] A super slow-setting concrete comprises the following raw materials: cement, water, coarse aggregate, fine aggregate, Wenlun glue, ethylenediaminetetramethylenephosphonic acid, coconut bran and admixtures.

[0053] The coarse aggregate is crushed gravel with a particle size of 5-25mm.

[0054] The fine aggregate is river sand with a particle size of 0.35-0.5mm.

[0055] The coconut bran is ordinary coconut bran and modified coconut bran, and the mass ratio of the modified coconut bran to the ordinary coconut bran is 1:0.3. The modified coconut bran adopts the modified coconut bran of Preparation Example 1.

[0056] The admixtures are steel slag powder, slag powder and fly ash, and the mass ratio of steel slag powder, slag powder and fly ash is 1:1.5:3.

[0057] The usage of each raw material is detailed in Table 1.

[0058] The present application also discloses a method for preparing super slow-setting concrete, comprising the following steps:

[0059] Step 01): Add 10% water into the reactor and adjust the temperature to 55° C. Then add Wenlun rubber, ethylenediaminetetramethylenephosphonic acid and coconut bran into the water and mix, stir until uniform, and obtain a premixed solution for standby use.

[0060] Step 02): Mix cement, remaining water and admixtures and stir until uniform.

[0061] Step 03): Add the premixed liquid into the material of step 02) and mix and stir until uniform.

[0062] Step 04): Continue to add coarse aggregate and fine aggregate to the material in step 03), mix and stir until uniform, and obtain the finished product.

[0063] Example 2

[0064] The invention discloses a super slow-setting concrete, which is different from the embodiment 1 in that the mass ratio of the modified coconut husk to the ordinary coconut husk is 1:0.7. The modified coconut husk is the modified coconut husk of the preparation example 2.

[0065] The admixtures are steel slag powder, slag powder and fly ash, and the mass ratio of steel slag powder, slag powder and fly ash is 1:2:2.

[0066] The usage of each raw material is different, please see Table 1 for details.

[0067] A method for preparing super slow setting concrete is different from that of Example 1 in that, in step 01), 20% water, i.e. 32 kg, is added into the reaction kettle; and the temperature is adjusted to 65°C.

[0068] Example 3

[0069] A super slow setting concrete, which is different from Example 1 in that the usage amount of each raw material is different, as shown in Table 1 for details.

[0070] Table 1

[0071]

[0072] Example 4

[0073] A super slow setting concrete, which is different from Example 1 in that the mass ratio of Wenlun glue, EDTA and coconut bran is 1.5:1:13. That is, the amount of Wenlun glue used is 1.5 kg, the amount of EDTA used is 1.0 kg, the amount of ordinary coconut bran used is 3 kg, and the amount of modified coconut bran used is 10 kg.

[0074] Example 5

[0075] A super slow setting concrete, which is different from Example 1 in that the mass ratio of Wenlun glue, ethylenediaminetetramethylenephosphonic acid and coconut bran is 3:2:8. That is, the amount of Wenlun glue used is 3kg, the amount of ethylenediaminetetramethylenephosphonic acid used is 2kg, the amount of ordinary coconut bran used is 1.8kg, and the amount of modified coconut bran used is 6.2kg.

[0076] Example 6

[0077] A super slow setting concrete, which is different from Example 1 in that the coconut bran is ordinary coconut bran, that is, the usage amount of ordinary coconut bran is 10 kg, and the usage amount of modified coconut bran is 0 kg.

[0078] Example 7

[0079] A super slow setting concrete, which is different from Example 1 in that the coconut bran is modified coconut bran, that is, the usage amount of ordinary coconut bran is 0 kg, and the usage amount of modified coconut bran is 10 kg.

[0080] Example 8

[0081] A super slow setting concrete, which is different from Example 1 in that the mass ratio of modified coconut bran to ordinary coconut bran is 1:2, that is, the usage amount of ordinary coconut bran is 3.3 kg, and the usage amount of modified coconut bran is 6.7 kg.

[0082] Example 9

[0083] A super slow setting concrete, which is different from Example 1 in that it also includes 3 kg of polycarboxylic acid water reducing agent.

[0084] A method for preparing super slow setting concrete, which is different from Example 1 in that a polycarboxylic acid-based water reducer is added in step 03) and mixed with the premixed liquid and the materials in step 02).

[0085] Example 10

[0086] A super slow setting concrete, which is different from Example 9 in that it also includes 6 kg of polycarboxylic acid water reducing agent.

[0087] Embodiment 11

[0088] A super slow setting concrete, which is different from Example 1 in that the admixture is steel slag powder, that is, the usage amount of steel slag powder is 100 kg, the usage amount of slag powder is 0 kg, and the usage amount of fly ash is 0 kg.

[0089] Comparative Example

[0090] Comparative Example 1

[0091] A super slow setting concrete, which is different from Example 1 in that the Wenlun glue is replaced by xanthan gum of equal mass, that is, the usage amount of the Wenlun glue is 0 kg, and the usage amount of the xanthan gum is 2.5 kg.

[0092] Comparative Example 2

[0093] A super slow setting concrete, which is different from Example 1 in that EDTA is replaced by an equal mass of sodium gluconate, that is, the amount of EDTA used is 0 kg, and the amount of sodium gluconate used is 1.6 kg.

[0094] Comparative Example 3

[0095] A super slow setting concrete, which is different from Example 1 in that coconut bran is replaced with wheat fiber of equal mass, that is, the amount of coconut bran used is 0 kg, and the amount of wheat fiber used is 10 kg.

[0096] Comparative Example 4

[0097] A super slow-setting concrete, which is different from Example 1 in that the amount of Wenlun glue used is 6 kg, the amount of ethylenediaminetetramethylenephosphonic acid used is 6 kg, and the amount of coconut bran used is 2.1 kg.

[0098] Performance testing

[0099] 1. Compressive strength: Referring to GB / T50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Ordinary Concrete", the concrete of Examples 1-11 and Comparative Examples 1-4 was tested for 28d compressive strength.

[0100] 2. Setting time: The setting time of the concrete of Examples 1-11 and Comparative Examples 1-4 was tested with reference to GB / T50080-2002 "Standard for Test Methods for Properties of Ordinary Concrete Mixtures", and the initial setting time and final setting time were recorded.

[0101] 3. Water seepage test: Referring to GB / T50080-2002 "Standard for Test Methods for Performance of Ordinary Concrete Mixtures", water seepage test was carried out on the concrete of Examples 1-11 and Comparative Examples 1-4, and the water seepage rate was recorded.

[0102] The test data of the above test are detailed in Table 2.

[0103] Table 2

[0104]

[0105] According to the comparison of the test data of Example 1 and Comparative Examples 1-3 in Table 2, it can be seen that the concrete obtained by arbitrarily replacing Wenlun glue, ethylenediaminetetramethylenephosphonic acid, and coconut bran on the basis of Example 1 to destroy the overall formula has a significant decrease in compressive strength, a significant shortening in setting time, and a greatly increased water seepage rate in water seepage detection. It shows that under the joint cooperation of Wenlun glue, ethylenediaminetetramethylenephosphonic acid, and coconut bran, it is conducive to the formation of an adsorption layer covering the surface of cement particles, thereby slowing down the hydration reaction; and it can also attract water molecules to form a dense water film in the outer layer, so that the water seepage rate can be reduced. Combined with the test data of Comparative Example 4, it can be seen that even if Wenlun glue, ethylenediaminetetramethylenephosphonic acid, and coconut bran are used, after destroying the matching ratio between the three, the compression resistance, slow setting, and water seepage performance of the obtained concrete are not satisfactory, indicating that Wenlun glue, ethylenediaminetetramethylenephosphonic acid, and coconut bran need to be matched in a specific ratio to fully exert the effect.

[0106] According to the comparison of the test data of Example 1 and Examples 2-5 in Table 2, it can be seen that within a certain dosage range, the floating of each raw material can still produce super slow-setting concrete with relatively excellent performance.

[0107] According to the comparison of the test data of Example 1 and Examples 6-8 in Table 2, it can be seen that the concrete prepared by using only modified coconut husk or only ordinary coconut husk still has higher compressive strength, longer setting time and lower water bleeding rate than Comparative Examples 1-4, but still has a gap compared with Example 1. This shows that the effect of mixing ordinary coconut husk and modified coconut husk for preparing super slow setting concrete is better. Furthermore, limiting the mixing of ordinary coconut husk and modified coconut husk in a specific ratio can also help improve the performance of super slow setting concrete.

[0108] According to the comparison of the test data of Example 1 and Examples 9 and 10 in Table 2, it can be seen that after adding the water reducing agent to the system, the compressive strength of the super slow setting concrete is improved and the water bleeding rate is also reduced.

[0109] According to the comparison of the test data of Example 1 and Example 11 in Table 2, it can be seen that the compressive strength of Example 11 is slightly worse than that of Example 1. This may be because the use of steel slag powder is beneficial to reducing water consumption, but is not conducive to improving hydration activity, thereby resulting in reduced strength. After further adjusting the specific types and usage ratios of admixtures, it is beneficial to ensure the performance of super-slow setting concrete in terms of compression resistance, slow setting, and anti-bleeding.

[0110] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A super slow setting concrete, characterized in that: According to the mass percentage, the raw materials include: 280-300 parts of cement, 160-175 parts of water, 1000-1200 parts of coarse aggregate, 700-900 parts of fine aggregate, 1-4 parts of Wenlun glue, 0.8-2.5 parts of ethylenediaminetetramethylenephosphonic acid, 5-15 parts of coconut bran, and 80-120 parts of admixture; The mass ratio of the Wenlun rubber, ethylenediaminetetramethylenephosphonic acid and coconut bran is (1.5-3.0): (1-2): (8-13).

2. The super slow setting concrete according to claim 1, characterized in that: The coconut bran includes modified coconut bran; The preparation method of modified coconut husk comprises the following steps: Take ammonia water with a mass concentration of 10-15%, soak ordinary coconut bran in the ammonia water for 6-12 hours, and then take it out to obtain modified coconut bran; When soaking, the mass ratio of ordinary coconut bran to ammonia water is 1: (3-5).

3. The super slow setting concrete according to claim 2, characterized in that: The coconut bran is composed of modified coconut bran and ordinary coconut bran, and the mass ratio of the modified coconut bran to the ordinary coconut bran is 1: (0.3-0.7).

4. The super slow setting concrete according to claim 1, characterized in that: In terms of mass fraction, the super slow setting concrete also includes 3-6 parts of polycarboxylic acid water reducing agent.

5. The super slow setting concrete according to claim 1, characterized in that: The admixture includes a mixture of one or more of steel slag powder, slag powder and fly ash.

6. The super slow setting concrete according to claim 1, characterized in that: The admixtures are steel slag powder, slag powder and fly ash, and the mass ratio of the steel slag powder, slag powder and fly ash is 1: (1.5-2): (2-3).

7. A method for preparing the super slow setting concrete according to any one of claims 1 to 6, characterized in that: The following steps are involved: Mixing Wenlun rubber, ethylenediaminetetramethylenephosphonic acid, coconut bran and 10-20% water to obtain a premix; Mix cement, remaining water and admixtures until uniform; Continue to add the premixed solution and mix until uniform; Then continue to add coarse aggregate and fine aggregate and mix until uniform to obtain the finished product.

8. The method for preparing super slow setting concrete according to claim 7, characterized in that: When the Wenlun rubber, ethylenediaminetetramethylenephosphonic acid, coconut bran and 10-20% of water are mixed, the mixing is carried out at a temperature of 55-65°C.

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