阅读说明：本技术 一种含再生砖骨料混凝土的二阶搅拌技术 (Second-order stirring technology for concrete containing recycled brick aggregate ) 是由 邓鹏� 杨文汐 黄靓 高畅 于 2021-06-21 设计创作，主要内容包括：本发明提供一种含再生砖骨料混凝土的二阶搅拌技术,具体步骤包括：纳米材料与溶有表面活性剂的自来水搅拌成纳米材料分散液；水泥、天然骨料及再生粗骨料混合干拌后,再加入所需的全部混凝土拌合水进行搅拌；在混凝土拌合物中加入纳米材料分散液,搅拌后所成纳米材料改性含再生砖骨料混凝土。本发明通过将纳米材料分散后同所有混凝土拌合物混合,填充孔隙结构,密实水泥与骨料间的界面过渡区,使制得的含再生砖骨料混凝土在坍落度、抗压强度和劈拉强度等力学性能方面均有所提高。(The invention provides a second-order stirring technology for concrete containing recycled brick aggregate, which comprises the following specific steps: stirring the nano material and tap water dissolved with a surfactant to form nano material dispersion liquid; mixing and dry-mixing cement, natural aggregate and recycled coarse aggregate, and then adding all required concrete mixing water for stirring; and adding the nano material dispersion liquid into the concrete mixture, and stirring to obtain the nano material modified concrete containing the recycled brick aggregate. According to the invention, the nano material is dispersed and then mixed with all concrete mixtures, the pore structure is filled, and the interface transition region between cement and aggregate is compacted, so that the mechanical properties of the prepared concrete containing the recycled brick aggregate, such as slump, compressive strength, split tensile strength and the like, are improved.)

1. A second-order stirring technology for concrete containing recycled brick aggregate is characterized in that: the method specifically comprises the following steps:

the first stage is as follows: (1) preparing a nano material dispersion liquid: stirring the nano material and tap water dissolved with a surfactant for 60 seconds to prepare nano material dispersion liquid; (2) preparing a concrete mixture: firstly, mixing cement, natural aggregate and recycled coarse aggregate for dry mixing for 30 seconds, then adding all required concrete mixing water for stirring for 30 seconds;

and a second stage: adding the nano material dispersion liquid into the concrete mixture, and stirring for 90 seconds to obtain a nano material modified concrete mixture containing recycled brick aggregate;

the two preparation processes of the first stage can be carried out simultaneously or sequentially.

2. The two-stage mixing technique for concrete containing recycled brick aggregate of claim 1, wherein the nano material is 10 g of nano silica or nano calcium carbonate or 1 g of multi-walled carbon nanotube.

3. The two-stage mixing technique for concrete containing recycled brick aggregate according to claim 1, wherein the active agent is 6 g of GA surfactant.

4. The second-order mixing technique of concrete containing recycled brick aggregate as claimed in claim 1, wherein the first stage of preparing the nano-material dispersion liquid is prepared by dissolving 6 g of GA surfactant in 200 g of water in advance and mixing uniformly, then adding the nano-material and manually and rapidly mixing uniformly.

5. The two-stage mixing technique for concrete containing recycled brick aggregate according to claim 1, wherein the first mixing is performed by ultrasonic dispersion for 10 minutes using an ultrasonic processor, and 0.13% of defoaming agent is used to obtain the final nanomaterial dispersion liquid.

6. The second-order mixing technique for concrete containing recycled brick aggregate of claim 1, wherein the recycled coarse aggregate is formed by mixing recycled red brick aggregate and recycled concrete aggregate in a certain proportion.

Technical Field

The invention relates to the technical field of building engineering materials, in particular to a second-order stirring technology for concrete containing recycled brick aggregate.

Background

With the development of urbanization and the generation of a large amount of construction waste, the preparation and use of recycled concrete have made remarkable progress in many countries. Compared with common concrete, the recycled concrete has more interface transition areas, adheres to high porosity and microcracks of old mortar, weakens particles and relaxes microstructures, and has weak strength, ductility and durability.

The nano material is applied to a concrete structure, and by virtue of the filling effect of a cement-based structure with a nano-scale size and the volcanic ash effect, the porosity of concrete can be reduced, the hydration reaction is accelerated, the interface transition area between cement and aggregate is compacted, and the mechanical property and the working property of the concrete are effectively improved. By adopting a second-order stirring technology, the nano material dispersion liquid is fused with the concrete mixture, and the microstructure and the mechanical property of the recycled concrete can be effectively improved.

At present, other materials are generally mixed in the existing stirring technology of the nano-material reinforced recycled concrete in China, for example, in the preparation method of the carbon fiber composite graphene reinforced recycled concrete with the existing patent number of 201610496305.5, the prepared concrete is more compact by mixing the nano-material graphene and the fiber material nano-carbon fiber, and the flexural strength and the compressive strength are greatly improved; in a method for modifying carbon fiber recycled concrete by using nano-silica disclosed in the prior patent No. 201910658557.7, the nano-silica is used for filling the pores inside the recycled aggregate, so that the compressive strength of the carbon fiber recycled concrete is enhanced; in the existing patent No. 202010691541.9, a nano-reinforcing method for recycled aggregate concrete and the obtained reinforced recycled aggregate are used, the nano-reinforcing method improves and strengthens the interface strength between the recycled aggregate and cement mortar through a secondary stirring process and a fly ash material, but the recycled coarse aggregate raw material needs to be soaked in a nano calcium carbonate solution for 30-60 min.

The results of the query show that the existing method mostly uses the nano material and other admixtures to compound and enhance the performance of the recycled concrete, the materials are complex, the cost is high, and the used recycled coarse aggregate is only recycled concrete aggregate. The performance parameters such as water absorption and crushing index of the recycled brick aggregate are different from those of recycled concrete aggregate, for example, the porosity, water absorption and crushing index of the recycled brick aggregate are all larger. Aiming at the problems, the second-order stirring technology for modifying the concrete containing the recycled brick aggregate by the nano material is provided, other synergistic reinforcing materials are not added, the stirring process is simple, the time consumption is short, the performance of the concrete containing the recycled brick aggregate is obviously improved, the requirement of engineering construction development can be met, the application of the recycled concrete can be popularized, the living environment is improved, and the resource protection is promoted.

Disclosure of Invention

In view of the above problems, the present invention aims to provide a second-order mixing technique suitable for concrete containing recycled brick aggregate, which is characterized in that cement, natural aggregate and recycled aggregate are mixed with all mixing water and then mixed with a nano material dispersion liquid by adjusting the mixing steps under the premise of ensuring the quality, so as to achieve the purpose of improving the mechanical properties and compressive strength of the recycled concrete.

In order to achieve the purpose, the technical scheme adopted by the invention is a second-order stirring technology for concrete containing recycled brick aggregate, which specifically comprises the following steps:

the first stage is as follows: (1) preparing a nano material dispersion liquid: stirring the nano material and tap water dissolved with a surfactant for 60 seconds to prepare nano material dispersion liquid; (2) preparing a concrete mixture: firstly, mixing cement, natural aggregate and recycled coarse aggregate for dry mixing for 30 seconds, then adding all required concrete mixing water for stirring for 30 seconds;

and a second stage: adding the nano material dispersion liquid into the concrete mixture, and stirring for 90 seconds to obtain a nano material modified concrete mixture containing recycled brick aggregate;

the two preparation processes of the first stage can be carried out simultaneously or sequentially.

The nano material is 10 g of nano silicon dioxide or nano calcium carbonate or 1 g of multi-wall carbon nano tube.

The active agent was 6 grams of GA surfactant.

When preparing the nano material dispersion liquid in the first stage, 6 g of GA surfactant is dissolved in 200 g of water in advance and is stirred uniformly, and then the nano material is put into the GA surfactant and is stirred uniformly by hand.

When the nano-material dispersion liquid is prepared in the first stage, if an ultrasonic processor is adopted, ultrasonic dispersion needs to be carried out for 10 minutes, and 0.13% of defoaming agent needs to be used to obtain the final nano-material dispersion liquid.

The recycled coarse aggregate is formed by mixing recycled red brick aggregate and recycled concrete aggregate according to a certain proportion.

The method is suitable for producing the nano material modified concrete containing recycled brick aggregate. The total stirring time and each stirring time are determined by tests according to the specific conditions of the stirring mode, the stirring effect, the nano material consumption, the total water consumption, the aggregate consumption, the cement type and the like of the stirrer.

Compared with the existing recycled concrete stirring technology, the invention has the beneficial effects that:

(1) according to the invention, the recycled aggregate, the natural aggregate and the cement are stirred together with all the free water, so that the degree of free water adsorption of the recycled aggregate is reduced, the free water in the concrete mixture is increased, and the slump of the concrete is improved;

(2) according to the invention, the nano material dispersion liquid is mixed with all concrete mixtures, so that the microstructure of each interface transition region is improved, and the compression strength and the splitting tensile strength of the recycled concrete are further improved;

(3) the invention simplifies the stirring process, greatly shortens the time for use, and improves the effective utilization rate of the nano material for enhancing the performance of the concrete containing the recycled brick aggregate.

Drawings

FIG. 1 is a flow chart of the second-order stirring technique of the present invention.

Detailed Description

In order to make the technical means and functions provided by the invention easily understood, the invention is specifically described in the following with reference to the attached tables and examples.

Example 1

The first stage is as follows: (1) preparing a nano material dispersion liquid: stirring the nano material and tap water dissolved with a surfactant for 60 seconds to prepare nano material dispersion liquid; (2) preparing a concrete mixture: firstly, mixing cement, natural aggregate and recycled coarse aggregate for dry mixing for 30 seconds, then adding all required concrete mixing water for stirring for 30 seconds;

and a second stage: adding the nano material dispersion liquid into the concrete mixture, and stirring for 90 seconds to obtain a nano material modified concrete mixture containing recycled brick aggregate;

the two preparation processes of the first stage can be carried out simultaneously or sequentially.

The recycled coarse aggregate is formed by mixing recycled red brick aggregate and recycled concrete aggregate according to a certain proportion.

For the recycled brick aggregate-containing concrete adopting nano-silica as the nano-material, when preparing the nano-material dispersion liquid in the first stage, 6 g of GA surfactant is dissolved in 200 g of water in advance and uniformly stirred, and 10 g of nano-silica is placed in the mixed liquid and manually and rapidly uniformly stirred.

Example 2

The first stage is as follows: (1) preparing a nano material dispersion liquid: stirring the nano material and tap water dissolved with a surfactant for 60 seconds to prepare nano material dispersion liquid; (2) preparing a concrete mixture: firstly, mixing cement, natural aggregate and recycled coarse aggregate for dry mixing for 30 seconds, then adding all required concrete mixing water for stirring for 30 seconds;

and a second stage: adding the nano material dispersion liquid into the concrete mixture, and stirring for 90 seconds to obtain a nano material modified concrete mixture containing recycled brick aggregate;

the two preparation processes of the first stage can be carried out simultaneously or sequentially.

The recycled coarse aggregate is formed by mixing recycled red brick aggregate and recycled concrete aggregate according to a certain proportion.

For the recycled brick aggregate-containing concrete adopting nano calcium carbonate as the nano material, when preparing the nano material dispersion liquid in the first stage, 6 g of GA surfactant is dissolved in 200 g of water in advance and is uniformly stirred, and 10 g of nano calcium carbonate is placed in the mixed liquid and is manually and rapidly uniformly stirred.

Example 3

The first stage is as follows: (1) preparing a nano material dispersion liquid: stirring the nano material and tap water dissolved with a surfactant for 60 seconds to prepare nano material dispersion liquid; (2) preparing a concrete mixture: firstly, mixing cement, natural aggregate and recycled coarse aggregate for dry mixing for 30 seconds, then adding all required concrete mixing water for stirring for 30 seconds;

and a second stage: adding the nano material dispersion liquid into the concrete mixture, and stirring for 90 seconds to obtain a nano material modified concrete mixture containing recycled brick aggregate;

the two preparation processes of the first stage can be carried out simultaneously or sequentially.

The recycled coarse aggregate is formed by mixing recycled red brick aggregate and recycled concrete aggregate according to a certain proportion.

For the recycled brick aggregate-containing concrete with the nano material being the multi-walled carbon nanotube, when the nano material dispersion liquid is prepared in the first stage, 6 g of GA surfactant is dissolved in 200 g of water in advance and is uniformly stirred, and 1 g of multi-walled carbon nanotube is placed in the mixed liquid and is manually and rapidly uniformly stirred.

Example 4

The first stage is as follows: (1) preparing a nano material dispersion liquid: stirring the nano material and tap water dissolved with a surfactant, performing ultrasonic dispersion for 10 minutes by using an ultrasonic processor, and eliminating bubbles generated in the treatment process of the dispersion by using 0.13% of a defoaming agent to obtain a nano material dispersion; (2) preparing a concrete mixture: firstly, mixing cement, natural aggregate and recycled coarse aggregate for dry mixing for 30 seconds, then adding all required concrete mixing water for stirring for 30 seconds;

and a second stage: adding the nano material dispersion liquid into the concrete mixture, and stirring for 90 seconds to obtain a nano material modified concrete mixture containing recycled brick aggregate;

the two preparation processes of the first stage can be carried out simultaneously or sequentially.

The recycled coarse aggregate is formed by mixing recycled red brick aggregate and recycled concrete aggregate according to a certain proportion.

Comparative example 1

The same materials as in example 1 were used and the stirring was carried out as follows:

stirring for the first time: stirring the nano material and tap water dissolved with a surfactant for 60 seconds to prepare nano material dispersion liquid;

stirring for the second time: adding the nano material dispersion liquid into the dried recycled coarse aggregate, adding the common dosage of concrete stirring water, and stirring for 60 seconds

Stirring for the third time: adding weighed cement, natural aggregate and the rest half of the stirring water, and stirring for 90 seconds to obtain the nano material reinforced concrete containing the recycled brick aggregate.

The recycled coarse aggregate is formed by mixing recycled red brick aggregate and recycled concrete aggregate according to a certain proportion.

For the recycled brick aggregate-containing concrete adopting nano-silica as the nano-material, when the nano-material dispersion liquid is prepared by first stirring, 6 g of GA surfactant is dissolved in 200 g of water in advance and uniformly stirred, and 10 g of nano-silica is placed in the mixed liquid and rapidly and manually stirred uniformly.

Comparative example 2

The same materials as in example 2 were used and the stirring was carried out as follows:

stirring for the first time: stirring the nano material and tap water dissolved with a surfactant for 60 seconds to prepare nano material dispersion liquid;

stirring for the second time: adding the nano material dispersion liquid into the dried recycled coarse aggregate, adding the common dosage of concrete stirring water, and stirring for 60 seconds

Stirring for the third time: adding weighed cement, natural aggregate and the rest half of the stirring water, and stirring for 90 seconds to obtain the nano material reinforced concrete containing the recycled brick aggregate.

The recycled coarse aggregate is formed by mixing recycled red brick aggregate and recycled concrete aggregate according to a certain proportion.

For the recycled brick aggregate-containing concrete adopting nano calcium carbonate as the nano material, when the nano material dispersion liquid is prepared by first stirring, 6 g of GA surfactant is dissolved in 200 g of water in advance and uniformly stirred, and 10 g of nano calcium carbonate is placed in the mixed liquid and is manually and rapidly uniformly stirred.

Slump, compressive strength and split tensile strength of standard test pieces which are subjected to standard curing for 28 days are tested on the recycled brick aggregate-containing concrete prepared by the stirring process in the examples and the comparative examples, and the test data are shown in table 1.

Table 1 experimental data of concrete sample containing recycled brick aggregate with 70% replacement rate of recycled coarse aggregate

From table 1, compared with the conventional stirring process, the concrete containing the recycled brick aggregate with the replacement rate of the recycled coarse aggregate of 70% obtained by stirring in the examples 1 to 4 has obvious advantages in slump, compressive strength and split tensile strength, and the applied second-order stirring technology ensures that the nano material is dispersed in the recycled concrete more uniformly and is suitable for preparing the concrete containing the recycled brick aggregate with better mechanical and working properties.

The above examples are only for illustrating the preferred embodiments of the present invention, and do not limit the scope of the present invention. In practice, any modification, addition or substitution made within the scope of the principles of the present invention, such as: according to the different selected cement dosage, recycled coarse aggregate composition and substitution rate, nano material type and dispersion mode for preparing concrete containing recycled brick aggregate, the dosage of nano material and stirring time in each step can be regulated, and the like, and the method falls into the protection scope contained in the invention.