KR102406849B1 - Composition of self-healing concrete using clinker binder and clinker aggregate - Google Patents

Abstract

The present invention relates to a self-healing concrete composition comprising a clinker binder and clinker aggregate.
The present invention increases the particle size of the inorganic mixed material through granulation of the inorganic mixed material, so that hydration occurs only on the surface during the initial hydration process of concrete, and the unreacted clinker remaining in the concrete is subjected to secondary hydration with the moisture that penetrated when cracking occurs. A self-healing concrete composition containing pulverized clinker binder and clinker aggregate with an optimal particle size distribution can be provided.

Description

Self-healing concrete composition containing clinker binder and clinker aggregate

The present invention relates to a self-healing concrete composition containing a clinker binder and clinker aggregate, and more particularly, to increase the particle size of the inorganic mixed material through granulation of the inorganic mixed material to hydrate only the surface portion during the initial hydration process of concrete. Clinker binder and clinker aggregate pulverized to an optimal particle size distribution are included so that the unreacted clinker remaining in the concrete after cracking causes secondary hydration with the infiltrated moisture to form hydrates in the cracks to heal the cracks in the long term. It relates to a self-healing concrete composition.

Reinforced concrete structures were recognized as semi-permanent structures in the past, but structural performance decreases due to corrosion of reinforcing bars due to infiltration of external harmful ions, and the structure collapses.

Cracks in the concrete structure are caused by reducing the durability by increasing the penetration rate by external factors that can cause corrosion of reinforcing bars such as chlorine ions and CO ₂ . Therefore, in order to secure the long-term durability of the structure, it is necessary to quickly repair the cracks in the concrete structure.

However, not only is it difficult to identify minute cracks in the structure, but also, in the case of civil structures, it is difficult to repair cracks because the scale is large and workers have difficulty accessing the cracks. Measures need to be taken against this.

Self-healing concrete technology refers to a technology that can heal cracks in concrete without external work.

This self-healing concrete technology is divided into inorganic mixed material utilization technology, bacteria utilization technology, capsule utilization technology, polymer material utilization technology, etc. depending on the material used. Among them, inorganic mixed material utilization technology refers to a technology that uses inorganic materials such as inorganic expanding agents, inorganic swelling agents, crystal accelerators, and cement substitutes (fly ash, fine blast furnace slag powder, silica fume, etc.) as self-healing materials.

Compared to other technologies, the inorganic mixed material utilization technology has the advantage that it can be easily applied to concrete compared to other materials because the cost of the self-healing material (inorganic mixed material) is low and processing is easy.

However, in the case of inorganic mixed materials, there is a problem that the self-healing performance decreases in the long term because it reacts and hardens during the hydration process of concrete. That is, the self-healing concrete technology using inorganic mixed materials as a self-healing material has a problem in that it is difficult to secure self-healing performance in the long term because all of the inorganic mixed materials react in the initial hydration process of concrete when mixed as it is.

Therefore, in order to secure the self-healing performance in the long term, it is necessary to prevent the inorganic mixed material from reacting at the initial age.

Therefore, when the particle size of the inorganic mixed material increases, only the surface of the inorganic mixed material particles is hydrated at the initial age and the inside remains unreacted, so the unreacted inorganic mixed material increases even at long-term age.

However, it is difficult to manufacture an inorganic mixed material with an appropriate diameter, and when the amount of reaction of the binder decreases, strength may decrease.

Therefore, there is a need for a technology that suppresses the reaction of the inorganic mixed material in the initial stage so that it remains in an unreacted state, thereby increasing the amount of the material that can re-react with the moisture that has penetrated after cracking.

Accordingly, some researchers have reported studies to overcome this by encapsulating an inorganic mixed material in order to suppress the initial reaction.

Patent Document 1 discloses a microcapsule, a composition for forming a self-healing coating material, a capsule dispersion type self-healing coating material and a method for manufacturing the same, and the disclosed microcapsule includes a core portion including a self-healing material and a fluorescent material, and a polymer, and a capsule membrane surrounding the core part.

However, the characteristic of the self-healing technology is that the amount of self-healing microcapsules is limited because most cases are applied as a protective film on the surface of the structure. This is because there is a problem such as prior leakage of the core material due to damage to the coating layer in the mixing process, etc., so the mixing amount is limited.

In order to solve this problem, Patent Document 2 not only allows the expression of a self-healing function in aggregate as a concrete material, but also exposes the self-healing composition to the outside during initial mixing due to damage to the coating in the case of direct mixing with cement composite material. We propose a method for manufacturing an aggregate with great applicability because it can control the

However, a series of encapsulation methods have a problem in that, if the capsule is not broken when a crack occurs, the self-healing performance is rather reduced, and the problem of low economic efficiency due to high encapsulation cost is pointed out.

Accordingly, the present inventors have tried to solve the problems of the prior art, as a result of granulating the inorganic mixed material to secure a long-term unreacted material, the granulation of the inorganic mixed material increases the particle size of the inorganic mixed material to suppress reactivity, In the initial concrete hydration process, hydration occurs only on the surface part by using a clinker binder and clinker aggregate, which is crushed clinker to a certain size, as an inorganic mixed material, and The present invention was completed by confirming that the unreacted clinker remaining in the concrete improves the self-healing performance of healing cracks by generating hydrates in the cracks by causing secondary hydration with the moisture that penetrated when cracks occur.

Korea Patent No. 1168038 (published on July 27, 2012) Korean Patent No. 1958444 (published on March 14, 2019)

It is an object of the present invention to provide a self-healing concrete composition comprising a clinker binder pulverized to a predetermined size by pulverizing clinker and clinker aggregate.

In order to achieve the above object, the present invention provides a clinker binder in which clinker is pulverized to a particle size distribution of 30 to 350 μm in a concrete composition in which cement and aggregate are blended with mixing water, and

Provided is a self-healing concrete composition comprising clinker aggregate pulverized to a particle size distribution of 80 to 2,500 μm.

In the above, 1 to 30% by weight of the clinker binder is alternately blended with the cement content, and the clinker binder is composed of a distribution ratio for each particle size according to a sieve size in the range of 30 to 350 μm when the clinker is pulverized.

In addition, 1 to 30% by weight of the clinker aggregate is alternately blended with the aggregate content, and the clinker aggregate is composed of a distribution ratio for each particle size according to a sieve size in the range of 80 to 2,500 μm when clinker is pulverized.

In this case, the clinker aggregate is preferably immersed in NaOH solution and surface-treated.

According to the self-healing concrete composition of the present invention, the unreacted amount that can be rehydrated by moisture penetration when cracks occur in the long term by using the clinker binder and clinker aggregate from crushed clinker as a self-healing material, and ultimately self-healing performance can be improved.

In addition, the technique of pulverizing clinker and using it as a self-healing material has a simpler procedure and less cost than a method of increasing the particle size by aggregating powder, so it can be manufactured more economically.

The present invention can improve self-healing performance by pulverizing clinker and replacing a part of the binder with clinker binder when mixing concrete and substituting a part of the aggregate with clinker aggregate, as well as clinker binder and clinker aggregate with different particle distribution By mixing them, it is also possible to prevent the decrease in strength.

1 shows an increase or decrease in the unreacted amount according to clinker granulation or atomization,
2 shows unreacted clinker around the cracks when cracks occur;
3 is a conceptual diagram showing the crack self-healing performance according to the size of the clinker binder;
4 is a photograph comparing the particle size of the pulverized clinker binder and clinker aggregate of the present invention;
5 shows the particle size distribution of the pulverized clinker binder of the present invention;
6 shows the particle size distribution of the pulverized clinker aggregate of the present invention,
7 is a water flow test setting photograph for evaluating the crack self-healing performance of the self-healing concrete composition of the present invention;
8 is a view showing the results of the permeability test method of the self-healing type concrete composition of the present invention,
9 is a result of observing the self-healing material generation around the clinker binder of the self-healing concrete composition of the present invention through CT.

Hereinafter, the present invention will be described in detail.

The present invention relates to a concrete composition in which cement and aggregate are blended with mixing water,

A clinker binder in which clinker is pulverized to a particle size distribution of 30 to 350 μm, and

Provided is a self-healing concrete composition comprising clinker aggregate pulverized to a particle size distribution of 80 to 2,500 μm.

More specifically, the present invention increases the particle size of the inorganic mixed material through granulation of the inorganic mixed material, so that hydration occurs only at the surface portion during the initial hydration process of concrete, and the inorganic mixed material remaining in the concrete is the moisture penetrating when cracks occur. It was devised to have long-term self-healing performance by generating hydrates in cracks by causing secondary hydration and clinker as an inorganic mixed material in the present invention.

In the present invention, clinker refers to a mass obtained by mixing lime (CaO), silica (SiO ₂ ), alumina (Al ₂ O ₃ ) and iron oxide (Fe ₂ O ₃ ) and gypsum, and calcining in a rotary kiln.

Clinker is easy to produce with the same quality, and it is easy to control the desired particle size through grinding.

1 shows an increase or decrease in the amount of unreacted clinker according to granulation or atomization of clinker, and shows an increase in unreacted clinker according to granulation of clinker (increase in diameter of particles).

More specifically, since hydration of the clinker binder and clinker aggregate starts from the surface, only the surface is reacted and the interior remains unreacted. Therefore, if granulated material is used, unreacted clinker increases in the long term. On the other hand, in the case of atomization of clinker, the unreacted amount decreases due to the hydration reaction starting from the surface.

FIG. 2 shows unreacted clinker at the periphery of a crack when a crack occurs. When the diameter is small, unreacted clinker existing around the crack decreases, and when the diameter is large, unreacted clinker existing around the crack increases. Accordingly, the self-healing performance is improved.

Also, as the unreacted clinker size on the crack surface increases, the self-healing performance of the crack width increases.

3 is a conceptual diagram illustrating crack self-healing performance according to the size of a clinker binder. Specifically, it can be seen that cracks with a larger width can be healed as the size of the clinker binder increases.

On the other hand, if the size of the clinker binder is too large, it is necessary to manufacture clinker of an appropriate size because the mechanical performance of concrete may decrease and quality deterioration such as bleeding may occur.

Therefore, in the present invention, the clinker binder pulverized to a particle size distribution of 30 to 350 μm and clinker aggregate crushed to a particle size distribution of 80 to 2,500 μm are substituted for the clinker to secure self-healing performance.

4 is a photograph comparing the particle sizes of pulverized clinker binder and clinker aggregate of the present invention, preferably selected according to the particle size distribution of the clinker binder (30 to 350 μm) and the particle size distribution of the clinker aggregate (80 to 2,500 μm). will be.

5 is a particle size distribution of the pulverized clinker binder of the present invention, and the clinker binder is composed of a distribution ratio for each particle size according to a sieve size in the range of 30 to 350 μm when clinker is pulverized.

Specifically, when the particle size distribution of the clinker binder is 30 to 350 μm, depending on the sieve size in the range of 30 to 350 μm when crushing the clinker, 30 μm particles are 22 wt%, 100 μm particles 48 wt%, 150 μm particles 20 wt. %, consisting of 10% by weight of 350 μm particles.

6 is a graph showing the particle size distribution of pulverized clinker aggregate of the present invention, wherein the clinker aggregate is composed of a distribution ratio for each particle size according to a sieve size in the range of 80 to 2,500 μm when clinker is pulverized. When the particle size distribution of the clinker aggregate is 80 to 2500 μm, the sieved particle size and distribution can be configured, and the optimal particle size of the above clinker binder and clinker aggregate can be adjusted according to the mixing conditions.

In the present invention, the clinker binder refers to a binder that replaces cement when designing a concrete mix, and clinker aggregate refers to a material used to replace fine aggregate (generally sand).

More specifically, with respect to 100 parts by weight of cement, in a concrete composition containing 200 to 300 parts by weight of aggregate with mixing water, 1 to 30% by weight of a clinker binder is alternately blended with the cement, and 1 to 30% by weight of clinker aggregate is added to the aggregate. 30% by weight can provide a self-healing concrete composition with an alternative blending.

Therefore, the present invention uses clinker binder pulverized to an appropriate size and clinker aggregate as a self-healing material to replace a part of the binder with the clinker binder when mixing concrete, and replace a part of the aggregate with clinker aggregate. In the course of hydration of , it is hydrated only on the surface part and in the long term, the unreacted inorganic mixed material remains inside the concrete to improve the self-healing performance when cracks occur. degradation can also be prevented.

The clinker binder is substituted up to 1 to 30% by weight of the cement. The clinker aggregate is substituted up to 1 to 30% by weight of the fine aggregate. At this time, when the substitution rate of the clinker binder is high, anhydrite was substituted by 10% of the substitution amount of the clinker binder in order to promote the reaction of the clinker binder. For example, if 10% of cement is replaced with clinker binder, 1% of anhydrite is replaced. This is to secure both the self-healing performance and the mechanical performance of the self-healing concrete.

If the clinker binder is less than 1% by weight, it is difficult to secure self-healing performance due to insufficient effect due to granulation of particles when blending with cement. Not desirable.

In addition, if the clinker aggregate is less than 1% by weight, the effect due to granulation of particles during aggregate mixing is insufficient, and when it exceeds 30% by weight, the self-healing performance is improved, but the strength may be reduced. At this time, the clinker aggregate may control the initial reaction by pretreating the surface. Preferably, surface treatment by immersion in NaOH solution for 1 to 5 minutes creates a thin film by hydrate on the surface of the clinker, so fluidity does not decrease in the initial stage of mixing, and the same self-healing performance can be secured in the long term.

7 is a water flow test setting photograph for evaluating the crack self-healing performance of a self-healing concrete composition containing clinker binder and clinker aggregate, which is crushed to a predetermined size by pulverizing clinker of the present invention, FIG. 8 shows the results of the permeability test method.

In the case of the self-healing formulation of Example 1 of the present invention, as a result of comparison with Comparative Example 1, which is a general formulation, the self-healing effect was confirmed by showing a slow water permeability in the self-healing formulation.

9 is a result of observing the generation of a self-healing material around the clinker binder through CT, and it can be confirmed that the generation of a self-healing material in the crack is promoted by the additional hydration reaction of the unreacted clinker binder located on the crack surface.

Hereinafter, the present invention will be described in more detail through examples.

These examples are for explaining the present invention in more detail, and the scope of the present invention is not limited to these examples.

<Example 1>

Step 1: Preparation of self-healing clinker binder and aggregate

1. A self-healing binder and clinker for preparing aggregate were prepared. At this time, the clinker must satisfy the chemical composition of Table 1 below. In order to increase the reactivity of the self-healing binder and aggregate, the content of C ₃ S and C ₃ A is 60.0% by weight and 10,0% by weight or more, respectively.

2. The prepared clinker was dried in an environment of low humidity (RH 50% or less) for 24 hours to prevent a hydration reaction with moisture in the air during the grinding process.

3. The clinker dried for 24 hours was pulverized with a physical crusher (Jaw Crusher, etc.) in a low humidity (RH 50% or less) environment. At this time, the device was adjusted so that the maximum dimension (diameter) of the sample ejected from the grinding device was 3 mm. In particular, if possible, in order to increase the yield of clinker binder and clinker aggregate, the minimum spacing during grinding is controlled to 30 μm.

4. The pulverized clinker was classified by particle size using a sieve. 4 is a photograph comparing the particle sizes of pulverized clinker binder and clinker aggregate. The particle size distribution of the clinker binder was set to be 30 to 350 μm, and the particle size distribution of the clinker aggregate was set to 80 to 2,500 μm. The optimum particle size of the clinker binder and the clinker aggregate may be adjusted according to the mixing conditions.

5 shows the particle size distribution of the pulverized clinker binder, and more specifically, when the particle size distribution of the clinker binder is 30 to 350 μm, in the total particle size distribution, 30 μm particles are 22 wt%, 100 μm particles 48 % by weight, 150 μm particles 20% by weight, and 350 μm particles 10% by weight.

In addition, Figure 6 shows the particle size of the crushed clinker aggregate. The particle size distribution of the clinker aggregate consists of 80 to 2,500 μm, and the specific particle size distribution is described in Table 2 below.

5. In order to control the fluidity of self-healing concrete, the initial reaction was controlled by pretreating the surface of the clinker aggregate. At this time, the pre-treatment method is a method of immersion in NaOH solution for 1 to 5 minutes. At this time, a thin film by hydrate is generated on the surface of the clinker, so fluidity deterioration does not occur at the beginning of mixing, and the same self-healing performance can be secured in the long term.

6. The clinker binder and clinker aggregate were separated and prepared in waterproof packaging so as not to react with moisture present in the air.

Step 2: Preparation of self-healing concrete

<Experimental Example 1> Self-healing performance evaluation

In Example 1, a clinker binder and clinker aggregate were prepared, and self-healing performance evaluation of a self-healing mortar using the same was performed.

An experiment was performed to evaluate the self-healing performance of self-healing concrete using the coating material according to the present invention.

For the experiment, a disk having a diameter of 100 mm and a height of 50 mm was made using the mixing ratio of Table 3 below. The general formulation was used for performance comparison with the self-healing formulation.

In order to induce cracks, the specimens were cured in a chamber at 23±1℃, RH 100% for 1 day after mixing, and then cured in water at 23±1℃ in a water bath until 28 days of age. After taking the 28-day-old specimen out of the water tank and inducing a penetration crack using UTM, a silicone sheet is placed at both ends of the specimen and fixed so that the crack width is 250±10 μm.

7 is a water flow test (water flow test) setting for crack self-healing performance evaluation of the self-healing concrete composition of the present invention, and the change in water permeation amount with time was measured.

8 shows the results of the permeability test method, the experiment was performed for a total of 28 days, and it can be seen that the greater the permeability reduction rate, the better the self-healing performance.

In the case of the self-healing formulation of Example 1 of the present invention, as a result of measuring the change in water flow for 28 days compared to Comparative Example 1, which is a general formulation, the general formulation decreased water permeability by about 60%, and the self-healing formulation was Pitching volume decreased by more than 90%. Accordingly, by showing a slow water permeability in the self-healing formulation, the self-healing effect was confirmed.

In addition, FIG. 9 is a result of observing the generation of self-healing material around the clinker binder through CT, showing that the generation of self-healing material in the crack is promoted by further hydration of the unreacted clinker binder located on the crack surface. could confirm that

In the above, the present invention has been described in detail only with respect to the described embodiments, but it is apparent to those skilled in the art that various changes and modifications are possible within the scope of the technical spirit of the present invention, and it is natural that such variations and modifications belong to the appended claims.

Claims (6)

Based on 100 parts by weight of cement, 200 to 300 parts by weight of aggregate are included in the concrete composition containing mixing water,
A clinker binder in which clinker is pulverized to a particle size distribution of 30 to 350 μm, and
Clinker aggregate pulverized to a particle size distribution of 80 to 1,600 μm is included,
A self-healing concrete composition in which 10 to 30% by weight of the clinker binder is alternately blended with the cement content, and 5 to 30% by weight of the clinker aggregate is alternately blended with the aggregate content. delete The method according to claim 1, wherein the clinker binder contains 22 wt% of 30 μm particles, 48 wt% of 100 μm particles, 20 wt% of 150 μm particles, and 10 wt% of 350 μm particles according to a checker in the range of 30 to 350 μm when the clinker is pulverized. A self-healing type concrete composition, characterized in that it is composed of a distribution ratio for each particle size. delete The self-healing concrete composition according to claim 1, wherein the clinker aggregate is composed of a distribution ratio for each particle size according to a sieve size in the range of 80 to 2,500 μm when the clinker is pulverized. delete

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