CN116589245A - Super-retarding concrete and preparation method thereof - Google Patents

Abstract

The application relates to the field of concrete, in particular to super-retarding concrete and a preparation method thereof. The super-retarding 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 hotplate rubber, 0.8-2.5 parts of ethylenediamine tetramethylene phosphonic acid, 5-15 parts of coconut husk and 80-120 parts of admixture; the preparation method comprises the following steps: mixing the temperature wheel glue, ethylenediamine tetramethylene phosphonic acid, coconut husk and 10-20% of water to obtain a premix; mixing cement, residual water and admixture until uniform; adding the premix solution continuously and mixing until uniform; and then adding coarse aggregate and fine aggregate continuously, and mixing until uniform to obtain a finished product. The application has the advantage of delaying the setting time of concrete.

Description

Super-retarding concrete and preparation method thereof

Technical Field

The application relates to the field of concrete, in particular to super-retarding concrete and a preparation method thereof.

Background

Along with the social development and the large engineering demands, the application range and the field of the concrete are wider and wider, and correspondingly, the requirements on the performance of the concrete are higher and higher.

In some large-scale construction projects such as bridges, the length of the piles and the width of the piles are often increased in order to improve the bearing capacity of the single piles. This directly results in a large volume of concrete being required for the mono pile and a long pouring time. If the lower layer is coagulated and the upper layer is not poured in the pouring process, the problems of pile breakage and the like can be caused, and the quality of the single pile is affected. Therefore, there is still a need for improvement.

Disclosure of Invention

The application provides super-retarding concrete and a preparation method thereof in order to delay the setting time of the concrete.

In a first aspect, the application provides super-retarding concrete, which adopts the following technical scheme:

the super-retarding 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 hotplate rubber, 0.8-2.5 parts of ethylenediamine tetramethylene phosphonic acid, 5-15 parts of coconut husk and 80-120 parts of admixture.

Through adopting above-mentioned technical scheme, under the joint coordination of warm wheel glue, ethylenediamine tetramethylene phosphonic acid, coconut husk, form even adsorbed layer on cement particle surface rapidly, cover on cement particle surface to effectively hinder cement particle and free water to combine, make hydration reaction speed become very slow, thereby play the retarding effect. In addition, the use of the three components greatly improves the hydrophilic effect, and a large amount of water molecules are attracted outside the adsorption layer to form a compact water film. Because the water molecules are attracted, even if the hydration reaction is slow, a large amount of water molecules are not separated out so as to cause serious bleeding. In the subsequent reaction, the attracted water molecules can timely and quickly react with cement particles to fully generate hydration reaction, so that the concrete is endowed with higher compressive strength.

In addition, as a water film is formed, the flocculation structure of the cement particles can be destroyed, free water can be released, and a certain water reducing effect is achieved; in addition, water and cement particles in the system can be fully dispersed, and the fluidity can be improved.

Preferably, the mass ratio of the temperature wheel glue to the ethylenediamine tetramethylene phosphonic acid to the coco coir is (1.5-3.0): (1-2): (8-13).

By adopting the technical scheme, under the condition of limiting the use amount of the thermal roller adhesive, the ethylenediamine tetramethylene phosphonic acid and the coco coir, the use proportion relation among the thermal roller adhesive, the ethylenediamine tetramethylene phosphonic acid and the coco coir is further limited, so that a more uniform adsorption layer is formed, the hydrophilic effect is improved to form a thicker water film, and the retarding time and the subsequent compressive strength of the concrete are improved.

Preferably, the coconut coir comprises modified coconut coir;

the preparation method of the modified coconut husk comprises the following steps:

taking ammonia water with the mass concentration of 10-15%, soaking common coconut coir in the ammonia water for 6-12h, and taking out to obtain modified coconut coir; when in soaking, the mass ratio of the common coconut husk to the ammonia water is 1: (3-5).

By adopting the technical scheme, the coconut coir is modified, so that hemicellulose and lignin in the coconut coir are dissolved out and decomposed into monosaccharides. Under the joint coordination of the modified coconut husk, the temperature wheel glue and the ethylenediamine tetramethylene phosphonic acid, the modified coconut husk reacts with calcium ions to generate calcium saccharate under an alkaline system of concrete reaction, so that the cement hydration reaction process becomes slow, and the retarding time is prolonged.

In addition, the modified coconut husk can make the adsorption layer cover the surface of the cement particles more easily and in a large area, so that the surfaces of the cement particles and the cement hydration particles are provided with the same charge, and the adsorption layer is repulsive, so that the dispersion effect is improved, the better water reducing effect is achieved, and the strength is improved.

Preferably, the coconut husk is composed of modified coconut husk and common coconut husk, and the mass ratio of the modified coconut husk to the common coconut husk is 1: (0.3-0.7).

The common coconut husk has rich pore structures, and when the common coconut husk is mixed with the temperature wheel glue and the ethylenediamine tetramethylene phosphonic acid, part of raw materials can be adsorbed into pores and are not easy to fall off, so that the common coconut husk has a more sufficient mixing effect, and a more compact and uniform adsorption layer is formed.

By adopting the technical scheme, the input proportion of the modified coconut coir and the common coconut coir is further limited, so that the full mixing of the raw materials can be ensured, and good dispersing effect can be ensured.

Preferably, the super-retarding concrete further comprises 3-6 parts of polycarboxylic acid water reducer according to parts by weight.

The polycarboxylic acid water reducer is added into the system, so that the water consumption required by the super-retarding concrete can be further reduced, and the strength is improved.

In addition, under the common combination of the temperature wheel glue, the ethylenediamine tetramethylene phosphonic acid, the cocoanut coir and the polycarboxylic acid water reducer, the electrostatic repulsive force when the water film is adsorbed on the surface of cement particles can be further enhanced, the mechanical strength of the water film is enhanced, and the water film is not easy to break in a short time.

Preferably, the admixture comprises one or more of steel slag powder, slag powder and fly ash.

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

By adopting the technical scheme, the admixture is further limited to be matched with specific types and specific proportions, so that the hydration activity of the steel slag powder, the slag powder and the fly ash can be fully exerted, the water consumption is reduced, and the strength of the concrete is improved.

In a second aspect, the application provides a preparation method of super-retarding concrete, which adopts the following technical scheme:

the preparation method of the super-retarding concrete comprises the following steps:

mixing the temperature wheel glue, ethylenediamine tetramethylene phosphonic acid, coconut husk and 10-20% of water to obtain a premix;

mixing cement, residual water and admixture until uniform;

adding the premix solution continuously and mixing until uniform;

and then adding coarse aggregate and fine aggregate continuously, and mixing until uniform to obtain a finished product.

Preferably, when mixing the temperature-sensitive glue, ethylenediamine tetramethylene phosphonic acid and coconut husk with 10-20% water, mixing is carried out at 55-65 ℃.

Preferably, when the premix liquid is added, 3-6 parts by mass of polycarboxylic acid water reducer is also added.

By adopting the technical scheme, the hot runner glue, the ethylenediamine tetramethylene phosphonic acid and the coconut husk are mixed in advance and are set to be mixed at a specific temperature, so that better dispersing and mixing effects in a system in the later period are facilitated.

In summary, the application has the following beneficial effects:

1. under the joint coordination of the temperature wheel glue, the ethylenediamine tetramethylene phosphonic acid and the coco coir, a uniform adsorption layer is rapidly formed on the surface of the cement particles and covers the surfaces of the cement particles, so that the cement particles are effectively prevented from being combined with free water, the hydration reaction speed is slow, and the retarder effect is achieved.

2. The use of the three components greatly improves the hydrophilic effect, and a large number of water molecules are attracted outside the adsorption layer to form a compact water film. Because the water molecules are attracted, even if the hydration reaction is slow, a large amount of water molecules are not separated out so as to cause serious bleeding. In the subsequent reaction, the attracted water molecules can timely and quickly react with cement particles to fully generate hydration reaction, so that the concrete is endowed with higher compressive strength.

3. The input proportion of the modified coconut husk and the common coconut husk is further limited, so that the full mixing of the raw materials can be ensured, and good dispersing effect can be ensured.

Detailed Description

The present application will be described in further detail with reference to examples.

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

Preparation example

Preparation example 1

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

step 1): and (5) drying the common coco coir, and grinding the common coco coir into powder for later use.

Step 2): and (3) taking ammonia water with the mass concentration of 10%, placing the common coconut coir processed in the step (1) into the ammonia water, standing and soaking for 12h.

When in soaking, the mass ratio of the coconut coir to the ammonia water is 1:3.

and 3) taking out the soaked common coco coir, filtering and drying to obtain the modified coco coir.

Preparation example 2

A modified coconut husk, which is different from the preparation example 1 in that:

the mass concentration of the ammonia water in the step 2) is 15%, the soaking time is 6h, and the mass ratio of the common coconut husk to the ammonia water is 1:5.

examples

Example 1

An ultra-retarding concrete comprises the following raw materials: cement, water, coarse aggregate, fine aggregate, hot wheel glue, ethylenediamine tetramethylene phosphonic acid, coco coir and an admixture.

The coarse aggregate is crushed gravel with the particle size of 5-25 mm.

The fine aggregate is river sand with the grain diameter of 0.35-0.5 mm.

The coconut husk is common coconut husk and modified coconut husk, and the mass ratio of the modified coconut husk to the common coconut husk is 1:0.3. modified coconut coir of preparation example 1 was used as modified coconut coir.

The admixture is steel slag powder, slag powder and fly ash, and the mass ratio of the steel slag powder to the fly ash is 1:1.5:3.

the specific amounts of the raw materials used are shown in Table 1.

The embodiment of the application also discloses a preparation method of the super-retarding concrete, which comprises the following steps:

step 01): 10% of water was put into a reaction kettle, and the temperature was adjusted to 55 ℃. Then adding the hotplate glue, ethylenediamine tetramethylene phosphonic acid and coco coir into water, mixing, stirring uniformly to obtain a premix for later use.

Step 02): mixing cement, residual water and admixture, and stirring until uniform.

Step 03): and then continuously adding the premix into the materials in the step 02), and mixing and stirring until the premix is uniform.

Step 04): and then adding coarse aggregate and fine aggregate into the material in the step 03), and mixing and stirring uniformly to obtain a finished product.

Example 2

The super retarding concrete is different from the embodiment 1 in that the mass ratio of the modified coconut husk to the common coconut husk is 1:0.7. the modified coconut coir of preparation example 2 was used.

The admixture is steel slag powder, slag powder and fly ash, and the mass ratio of the steel slag powder to the fly ash is 1:2:2.

the amounts of the raw materials used are different, and are shown in Table 1 in detail.

The preparation method of the super retarding concrete is different from the embodiment 1 in that 20% of water, namely 32kg, is added into the reaction kettle in the step 01); the temperature was adjusted to 65 ℃.

Example 3

The super retarding concrete is different from the concrete of example 1 in that the amounts of the raw materials used are different, and the specific details are shown in Table 1.

TABLE 1

Example 4

The super retarding concrete is different from the embodiment 1 in that the mass ratio of the temperature wheel glue, the ethylenediamine tetramethylene phosphonic acid and the coco coir is 1.5:1:13. namely, the use amount of the thermal roller glue is 1.5kg, the use amount of the ethylenediamine tetramethylene phosphonic acid is 1.0kg, the use amount of the common coconut husk is 3kg, and the use amount of the modified coconut husk is 10kg.

Example 5

The super retarding concrete is different from the embodiment 1 in that the mass ratio of the temperature wheel glue, the ethylenediamine tetramethylene phosphonic acid and the coco coir is 3:2:8. namely, the use amount of the thermal roller glue is 3kg, the use amount of ethylenediamine tetramethylene phosphonic acid is 2kg, the use amount of common coconut husk is 1.8kg, and the use amount of modified coconut husk is 6.2kg.

Example 6

An ultra-retarding concrete is different from example 1 in that the coconut husk is common coconut husk, i.e. the use amount of common coconut husk is 10kg, and the use amount of modified coconut husk is 0kg.

Example 7

An ultra-retarding concrete is different from example 1 in that the coconut husk is modified coconut husk, that is, the use amount of common coconut husk is 0kg, and the use amount of modified coconut husk is 10kg.

Example 8

The super retarding concrete is different from the embodiment 1 in that the mass ratio of the modified coconut husk to the common coconut husk is 1:2, namely the using amount of the common coconut husk is 3.3kg, and the using amount of the modified coconut husk is 6.7kg.

Example 9

An ultra-retarding concrete is different from example 1 in that it further comprises 3kg of a polycarboxylic acid type water reducing agent.

The preparation method of the super retarding concrete is different from the embodiment 1 in that the polycarboxylic acid water reducer is added in the step 03) and is mixed with the premix and the materials in the step 02).

Example 10

An ultra-retarding concrete is different from example 9 in that it further comprises 6kg of a polycarboxylic acid water reducer.

Example 11

The super retarding concrete is different from the embodiment 1 in that the admixture is steel slag powder, namely, the usage amount of the steel slag powder is 100kg, the usage amount of the slag powder is 0kg, and the usage amount of the fly ash is 0kg.

Comparative example

Comparative example 1

An ultra-retarding concrete is different from example 1 in that the temperature wheel glue is replaced with xanthan gum of equal mass. Namely, the amount of the temperature roller gum is 0kg, and the amount of the xanthan gum is 2.5kg.

Comparative example 2

An ultra-retarding concrete is different from example 1 in that ethylenediamine tetramethylene phosphonic acid is replaced with sodium gluconate of equal mass. Namely, the amount of ethylenediamine tetramethylene phosphonic acid used was 0kg, and the amount of sodium gluconate used was 1.6kg.

Comparative example 3

An ultra retarding concrete is different from example 1 in that coconut coir is replaced with equal mass of wheat fiber. That is, the amount of coconut coir used was 0kg, and the amount of wheat fiber used was 10kg.

Comparative example 4

The super retarding concrete is different from the embodiment 1 in that the use amount of the temperature roller glue is 6kg, the use amount of the ethylenediamine tetramethylene phosphonic acid is 6kg, and the use amount of the coco coir is 2.1kg.

Performance test

1. Compressive strength: the concrete of examples 1-11 and comparative examples 1-4 was tested for 28d compressive strength with reference to GB/T50081-2019 Standard for physical mechanical Properties test method of ordinary concrete.

2. Coagulation time: the setting time of the concrete of examples 1 to 11 and comparative examples 1 to 4 was measured with reference to GB/T50080-2002 Standard for test methods for Performance of concrete mixtures, and the initial setting time and final setting time were recorded.

3. Bleeding test: the concrete of examples 1 to 11 and comparative examples 1 to 4 were subjected to bleeding test with reference to GB/T50080-2002 Standard for test methods for Performance of concrete mixtures, and bleeding rates were recorded.

The test data of the above test are shown in Table 2.

TABLE 2

As is clear from comparison of the test data of example 1 and comparative examples 1 to 3 in Table 2, the concrete obtained by arbitrarily replacing the hot runner glue, ethylenediamine tetramethylene phosphonic acid, and coconut husk on the basis of example 1 to destroy the whole formulation had a significant decrease in compressive strength, a significant decrease in setting time, and a significant increase in bleeding rate in bleeding test. The method is favorable for generating an adsorption layer covering the surface of cement particles under the joint coordination of the hotplate glue, ethylenediamine tetramethylene phosphonic acid and coco coir, thereby retarding hydration reaction; and can also attract water molecules to form a compact water film on the outer layer, so that the bleeding rate is reduced. The test data of comparative example 4 shows that even though the temperature-sensitive glue, the ethylenediamine tetramethylene phosphonic acid and the coconut husk are used, the compression resistance, the retarding and the bleeding performance of the prepared concrete are not satisfactory after the mixing proportion among the three is destroyed, which indicates that the temperature-sensitive glue, the ethylenediamine tetramethylene phosphonic acid and the coconut husk are required to be mixed in a specific proportion to fully exert the effect.

As can be seen from comparison of the test data of example 1 and examples 2-5 in Table 2, the floating of each raw material can still produce super-retarding concrete with relatively excellent performance within a certain dosage range.

From comparison of the test data in Table 2 for examples 1 and examples 6-8, it can be seen that the concrete prepared using only modified coconut coir or only ordinary coconut coir, while still having higher compressive strength, longer setting time, lower bleeding rate than comparative examples 1-4, is still a difference from example 1. The effect of preparing super-retarding concrete after mixing the common coco coir and the modified coco coir is better. Furthermore, the mixing of the common coco coir and the modified coco coir in a specific proportion is limited, which is beneficial to improving the performance of the super-retarding concrete.

As can be seen from comparison of the test data of example 1 and examples 9 and 10 in Table 2, the compressive strength of the super-retarding concrete is improved and the bleeding rate is also reduced after the water reducer is added into the system.

As can be seen from comparison of the test data of example 1 and example 11 in Table 2, the compressive strength of example 11 is slightly inferior to that of example 1. It is possible that the use of the slag powder is advantageous in reducing the water consumption, but is disadvantageous in improving the hydration activity, resulting in a decrease in strength. After the specific types and the use proportion of the admixture are further adjusted, the super-retarding concrete is beneficial to ensuring the performances of the super-retarding concrete in the aspects of compression resistance, retarding, bleeding resistance and the like.

The present embodiment is only for explanation of the present application and is not to be construed as limiting the present application, and modifications to the present embodiment, which may not creatively contribute to the present application as required by those skilled in the art after reading the present specification, are all protected by patent laws within the scope of claims of the present application.

Claims (9)

1. The super-retarding concrete is characterized by comprising the following raw materials in parts by weight: 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 hotplate rubber, 0.8-2.5 parts of ethylenediamine tetramethylene phosphonic acid, 5-15 parts of coconut husk and 80-120 parts of admixture.

2. The ultra-retarded concrete according to claim 1, wherein: the mass ratio of the temperature wheel glue to the ethylenediamine tetramethylene phosphonic acid to the coco coir is (1.5-3.0): (1-2): (8-13).

3. The ultra-retarded concrete according to claim 1, wherein: the coconut coir comprises modified coconut coir;

the preparation method of the modified coconut husk comprises the following steps:

taking ammonia water with the mass concentration of 10-15%, soaking common coconut coir in the ammonia water for 6-12h, and taking out to obtain modified coconut coir;

when in soaking, the mass ratio of the common coconut husk to the ammonia water is 1: (3-5).

4. A super retarding concrete according to claim 3, wherein: the coconut husk consists of modified coconut husk and common coconut husk, and the mass ratio of the modified coconut husk to the common coconut husk is 1: (0.3-0.7).

5. The ultra-retarded concrete according to claim 1, wherein: according to the mass parts, the super retarding concrete also comprises 3-6 parts of polycarboxylate water reducer.

6. The ultra-retarded concrete according to claim 1, wherein: the admixture comprises one or more of steel slag powder, slag powder and fly ash.

7. The ultra-retarded concrete according to claim 1, wherein: the admixture is steel slag powder, slag powder and fly ash, and the mass ratio of the steel slag powder to the fly ash is 1: (1.5-2): (2-3).

8. A method for preparing super retarding concrete based on any one of claims 1 to 7, comprising the following steps:

mixing the temperature wheel glue, ethylenediamine tetramethylene phosphonic acid, coconut husk and 10-20% of water to obtain a premix;

mixing cement, residual water and admixture until uniform;

adding the premix solution continuously and mixing until uniform;

and then adding coarse aggregate and fine aggregate continuously, and mixing until uniform to obtain a finished product.

9. The method for preparing super retarding concrete according to claim 8, wherein: mixing the temperature wheel glue, ethylenediamine tetramethylene phosphonic acid and coconut husk with 10-20% water at 55-65deg.C.