KR20220091627A - Cement-based conductive composite controlled the expansion by aluminum - Google Patents

Abstract

The present invention relates to a cement-based composition such as cement paste, mortar, concrete, etc., which ensures conductivity by being mixed with aluminum. Provided is a cement-based conductive composition which suppresses foam expansion due to reaction of calcium hydroxide and aluminum by coating a surface of the aluminum, and minimizes the deterioration of physical properties (fluidity, compressive strength, etc.) due to the mixing of the aluminum. The present invention provides a cement-based conductive composition capable of controlling foam expansion of aluminum by mixing 20 to 25 parts by weight of aluminum pieces whose surfaces are coated with respect to 100 parts by weight of cement.

Description

Cement-based conductive composite controlled the expansion by aluminum

The present invention relates to a cement-based composition such as cement paste, mortar, concrete, etc., in which aluminum is mixed to ensure conductivity, and by coating an aluminum surface, it suppresses foaming and expansion due to the reaction of calcium hydroxide with aluminum, and physical properties ( It relates to a cement-based conductive composition in which deterioration of fluidity, compressive strength, etc.) is minimized.

The trend of the global construction industry is changing from 'efficiency' to 'safety', and the domestic construction industry is also riding on this trend. In the case of Korea, most roads are vulnerable to natural disasters such as fog, rainfall, and heavy snow due to the nature of the terrain where there are many mountains and rivers, so there is a high risk of direct accidents and secondary accidents.

In addition, while winter has been getting shorter over the past 80 years due to global warming, etc., signs of abnormal climate such as localized sudden snowfall are continuously increasing. In addition, the frequency of natural disasters in winter, such as heavy snowfall and storms, has been increasing for the past 10 years, and the incidence of icy road accidents due to the continued sub-zero temperature is also increasing. Under this circumstance, 199 people died in road icing accidents in Korea over the past 5 years.

In order to prevent human casualties due to such a freezing accident, measures such as sand and calcium chloride are applied, and measures are being taken to remove snow and ice through the operation of snow plows and manpower. In the case of sand laying, it is difficult to apply it to a mass work section because it causes clogging of drains by sand and environmental problems after thawing, which can cause secondary damage, and requires enormous manpower and equipment. In the case of Seoul, since 2010, about 1,000 snow removal vehicles and 3,000 manpower have been mobilized every year, and it is estimated that 220,000 bags (7,000 tons) of snow removal agent are sprayed annually. However, problems such as environmental problems caused by indiscriminate spraying of snow removal agents such as calcium chloride and sodium chloride and damage to vehicles other than structures were confirmed.

[Reference 1]

In addition, black ice, which has recently emerged as the biggest issue in accidents due to icing on the road, is so thin and transparent that it projects the asphalt color of the road as it is, making it inconspicuous while driving, leading to accidents due to driver's carelessness. Generally, snow and rain that fell during the day seep into the cracks in the asphalt, and then mix with oil and dust during the night and freeze thinly on the road. However, when the snow remover is combined with the snow on the road, the residual moisture on the road makes the surface more slippery and black ice occurs more frequently. .

In addition to the aforementioned sand spray and snow removal agent, the use of snowmelting liquid, heating wire and heat pipe technology, etc. are being applied to road icing prevention. The types and characteristics of the existing road snow removal methods are summarized in [Reference Table 1] below.

[Reference Table 1] - Types and Characteristics of Snow Removal Methods

However, it is confirmed that the snow melt causes corrosion of metal materials, is harmful to vehicles and road facilities, and causes re-freezing and secondary environmental problems. The heating wire or heat pipe method utilizes heat generated through electricity or other energy sources, and it has disadvantages such as the difficulty of system maintenance and the need for re-construction, and the cost of securing power or heat sources is also excessive.

[Reference Figure 2] - Types of existing snow melting systems

Therefore, there is a need to develop a road snow melting and ice melting method that can minimize pollution and system failure, facilitate repair and maintenance, and reduce costs.

On the other hand, general concrete is based on materials that can be easily obtained from nature, and has excellent strength, durability, and economic feasibility, so it is widely used as a building and civil engineering material. Although such concrete has very low electrical conductivity as an insulator, it can be used as an electrically conductive material having specific resistance through mixing of a material having electrical conductivity. Recently, there have been many development studies and attempts on concrete that imparts electrical conductivity to concrete using this principle and exhibits heat-generating performance through it. By applying a voltage to both ends of the concrete that has electrical conductivity, when an electric current flows, electricity is conducted and heat is generated. The technology can be applied to frozen areas such as highways, airport runways, docks around ship ports, and underground parking lot entrance ramps. In addition, studies on changes in electrical resistance, electrical conductivity, and heat generation performance of concrete prepared by mixing conductive materials such as graphite, coke, carbon black and carbon fiber have been conducted until recently. This conductive heating concrete does not cause environmental pollution, structural damage or corrosion, unlike the existing snow removal agent and snowmelting liquid application method, and is expected to be a good solution in terms of energy saving.

In general, metallic materials have high electrical conductivity, and are silver (6.29 × 10 ⁵ S/cm), copper (5.98 × 10 ⁵ S/cm), gold (4.26 × 10 ⁵ S/cm), and aluminum (3.77 × 10 5 S/cm). 10 ⁵ S/cm) and iron (1.03 × 10 ⁵ S/cm) were confirmed to have excellent electrical conductivity. Among them, iron is sometimes applied in the form of steel fibers to improve the electrical conductivity of mortar or concrete. In the case of aluminum, as a lightweight metal material, it has advantages such as high specific strength, workability, excellent corrosion resistance and non-toxicity to the human body, and is a material applied to various industrial fields. However, when applied to cement-based compositions such as cement paste, mortar, and concrete, it has been recognized as a material that is difficult to be incorporated into cement-based compositions due to the property of reacting with cement and foaming. The principle of how aluminum reacts with cement is as follows.

Among the compounds present in Portland cement, C3S (tricalcium silicate, 3CaO•SiO ₂ ) and C2S (dicalcium silicate, 2CaO•SiO ₂ ), which account for a large proportion of the compounds present in Portland cement, react with water below [Equation 1] and [Equation 2], respectively. Calcium oxide (Ca(OH) ₂ ) and calcium silicate hydrate (CSH) are produced through the same process.

[Equation 1]

[Equation 2]

At this time, the generated calcium hydroxide reacts with aluminum as shown in the reaction formulas of [Equation 3] and [Equation 4] below, respectively, to generate hydrogen gas, and bubbles are generated inside the cement-based composition.

[Equation 3]

[Equation 4]

Although aluminum is not applied to mortar and concrete for the above reasons, aluminum is widely used in various industrial fields, so its usage and discharge are vast. In particular, in the case of aluminum cans, it is estimated that 1.236 billion units are consumed annually.

1. Patent Publication 10-2009-0117259 "Conductive cement composition and anticorrosive method using same" 2. Registered Patent 10-0328539 "Exothermic cement mortar or concrete composition, heating element and manufacturing method thereof" 3. Registered Patent 10-0234577 "Electrically conductive heating concrete using cement"

The present invention is a primary goal of deriving a method for applying an abandoned aluminum can as a building material, by controlling the foaming phenomenon that occurs when aluminum is applied to a cement-based composition to minimize the deterioration of properties, and to improve electrical conductivity was meant to improve.

Accordingly, the secondary goal is to solve the problem of icy roads and black ice in winter by deriving a conductive cement-based composition using an aluminum can as a raw material.

The present invention provides "a cement-based conductive composition in which the foaming and expansion of aluminum is controlled by mixing 20 to 25 parts by weight of an aluminum piece with a coated surface compared to 100 parts by weight of cement."

The aluminum piece can be applied by cutting an aluminum can into a square with a width of 2 to 4 mm and a length of 2 to 4 mm, and is composed of 20 to 70 wt% of vegetable oil, 20 to 50 wt% of rosin, and 5 to 15 wt% of surfactant. It can be coated with a coating solution.

The coating treatment is carried out by maintaining the aluminum piece precipitated in the coating solution at 15 to 25° C. for 2 hours or more, and then drying the aluminum piece at 100° C. for 24 hours or more after removing the aluminum piece from the coating solution. can

According to the present invention described above, the following effects can be obtained.

1. The reaction between aluminum and cement reactant (calcium hydroxide) can be controlled to suppress foaming expansion by performing a pretreatment of coating the surface before incorporating the aluminum piece into the cement-based composition.

2. By cutting an aluminum can and applying it to the present invention, a large amount of household waste can be turned into a building material.

3. Considering the improvement of electrical conductivity and reduction of compressive strength according to the mixing amount of aluminum pieces, the mixing amount of aluminum pieces was derived from 20 to 25 parts by weight compared to 100 parts by weight of cement, thereby maximizing resource utilization efficiency.

4. By applying the present invention to mortar for road construction, concrete, etc., it is possible to perform snow removal and ice making operations utilizing the heat effect caused by electricity conduction.

[FIG. 1] is a photograph of the cut aluminum can raw material.
[Fig. 2] is a schematic diagram of mortar test body production.
[FIG. 3] is a photograph of the electrical conductivity measurement test process of the mortar specimen.
[Fig. 4] is a photograph of the surface state of each specimen according to the pre-treatment state of the aluminum piece.
[Fig. 5] is a graph showing the electrical conductivity characteristics of each specimen by curing date.
[Fig. 6] is a graph of the electric current during curing for 28 days according to the mixing amount of coated aluminum.
[Fig. 7] is a graph of compressive strength by curing day according to the amount of coated aluminum mixed.

The present invention provides "a cement-based conductive composition in which foaming and expansion by aluminum is controlled by mixing 20 to 25 parts by weight of an aluminum piece with a coated surface compared to 100 parts by weight of cement."

As used herein, the term 'cement-based composition' is a generic term for cement paste (slurry), mortar, and concrete.

As the aluminum piece, as shown in [FIG. 1], an aluminum can (beer can, beverage can, coffee can, etc.) may be cut into a square of 2 to 4 mm in width and 2 to 4 mm in length.

The surface coating treatment of the aluminum piece is to block the reaction between aluminum and cement reactants (calcium hydroxide) while maintaining the electrical conductivity of aluminum, and is made with 20 to 70 wt% of vegetable oil, 20 to 50 wt% of rosin, and 5 to 15 wt% of surfactant. The surface of the aluminum piece can be coated with the coating solution made. Accordingly, an oil component-based coating film is formed on the surface of the aluminum piece, the reaction between calcium hydroxide and aluminum is suppressed, and as a result, the foaming phenomenon is controlled.

In the coating treatment, the aluminum piece is maintained at 15 to 25° C. for 2 hours or more (preferably 2 hours or more and within 3 hours, most preferably 2 hours) in a state in which the aluminum piece is precipitated in the coating solution, and in the coating solution After removing the aluminum piece, it may be carried out in a process of drying at 100° C. for 24 hours or more (preferably 24 hours or more and less than 25 hours, most preferably 24 hours).

Hereinafter, the present invention will be described in detail with specific test examples.

Specimens for the test were prepared with 'mortar' mixed with cement, sand, and water. [Table 1] below shows the test sample mortar mixing ratio. The amount of cement was fixed at 198g and the amount of fine aggregate (sand) at 594g, and aluminum pieces were added at intervals of 5wt% in the range of 0~25wt% of the cement weight. The name of each specimen is indicated according to the mixing amount of the aluminum piece.

Since the fluidity (workability) of the mortar composition decreases as the mixing amount of the aluminum piece increases, the water-cement ratio (W/C) was set variably for each specimen to satisfy the mortar flow range of 190±10 mm.

For the cement used in the test, type 1 ordinary Portland cement, and fine aggregate, artificial silica sand No. 6, was used. The aluminum piece was cut from an aluminum can to a size of 3 mm × 3 mm, and only the side surfaces were used after cutting the upper and lower surfaces. In order to remove foreign substances from the inner wall of the aluminum can, washing and drying processes were performed after the cutting operation.

Before putting the aluminum piece prepared as above into the mortar, a surface coating operation for controlling foaming was performed. The coating solution for this can be applied as described above, consisting of 20~70wt% of vegetable oil, 20~50wt% of rosin, and 5~15wt% of surfactant, and in this test, 50wt% of vegetable oil extracted from soybean in this test. , 40% rosin and 10wt% of surfactant were mixed and applied.

After precipitating the aluminum piece in the coating solution and maintaining it at room temperature (15-25° C.) for 2 hours, the remaining coating solution and the aluminum piece are separated using a sieve, and then dried at 100° C. for 24 hours, the surface of the aluminum piece coating was made.

For each test specimen, the aluminum piece is mixed with the mortar material (cement, fine aggregate, water) by a set amount, and then mixed at low speed for 1 minute (rotation 140±5rpm, revolution 62±5rpm) and high-speed mixing for 30 seconds (rotation 285±10rpm) , idling 125±10rpm), and scraping off raw materials that were in close contact with the floor for 15 seconds and had a rest time of 1 minute and 15 seconds. After high-speed mixing for 1 minute again, the mixed mortar is put in the mold (40mm×40mm×160mm) twice, and 60 times per one time using the Jolting Table (ELE, 39-1150, UK). The jolting process was performed. After that, the mold was filled and excess mortar was removed, the top was flattened, and copper wires were buried at a distance of about 10 mm from both ends as shown in [Fig. 2].

After the molding was completed, the mold was exposed for 24 hours in an environment of 23°C-RH 90%, and then demolding was performed. After that, the specimen for electrical conductivity measurement was cured for 28 days in an environment similar to the domestic average temperature and humidity conditions (23℃-RH 60%), and the specimen for measuring basic properties was cured in water at 23℃ for 3, 7, and 28 days. did

The electrical conductivity of each specimen was measured as shown in [Fig. 3], and the current for each curing period of 3, 7, and 28 days was measured when 100V voltage was applied using a DC voltage supply device (Agilent Technologies, Inc., 6634B, USA). In addition, the resistance and electrical conductivity characteristics of each specimen by curing day were calculated through the measured current. Thereafter, the compressive strength of each specimen at 3, 7, and 28 days was measured.

[Fig. 4] shows the surface state of each specimen according to the pre-treatment state of the aluminum piece by photographing it. [Fig. 4] shows the cured state of the mortar specimen in which 20 wt% of the aluminum specimen is mixed with the cement, but (b) and (d) of [Fig. '), the foaming phenomenon occurred by the hydrogen gas generated by the principle of [Equation 1] to [Equation 4] described in the [Technology behind the invention] section, and the bubble was formed and the top of the specimen was swollen. status has been confirmed.

On the other hand, in the mortar in which the aluminum pieces (hereinafter, 'coated aluminum pieces') that were surface-coated with the coating solution were mixed, foaming did not occur as in the forms (a) and (c) of [Fig. 4]. , the top surface state remained flat.

[Table 2] below shows the calculated change ratio by measuring the height of each specimen to quantify and compare the expansion of the mortar. The left, center, and right sides of the upper surface of each specimen were specified as points A, B, and C, respectively, and the heights were measured to calculate the average, and the expansion ratio was derived based on the mold height (40 mm).

The average height of the coated aluminum mixed test specimen was 40.35 mm, and the expansion ratio was 100.8%, which is judged to be a value that falls within the error range of the state in which expansion is not actually made.

On the other hand, the uncoated aluminum mixed specimen had an average height of 45.02 mm, and showed an expansion rate of 112.6% compared to the reference height. The test specimen showed an external change that could be confirmed with the naked eye, and the width of change was so large that the expansion height reached about 15.8 times that of the coated aluminum specimen. These results indicate that, in the coated aluminum mixture test specimen, the coating state of the aluminum piece is not damaged even during mortar mixing and curing, and the foaming phenomenon is controlled by preventing contact and reaction between aluminum and cement.

[Fig. 5] is a graph showing the measured current and resistance values for each curing date of each specimen. All of the aluminum pieces mixed in the following specimens are coated aluminum pieces.

When 100V was applied, the current for each curing day (3, 7, and 28 days) of the AL0% specimen was 0.0192A, 0.0061A, and 0.0019A, respectively, and the current value at 28 days of age was only 9.9% compared to 3 days of age. level has dropped significantly.

The current for each curing day (3, 7, 28 days) of the AL5% specimen was measured as 0.0342A, 0.0121A, and 0.0025A, and the AL10% specimen was 0.0423A, 0.0198A, and 0.0073A. As the curing period increased, the measured current increased. decreased. However, in the case of 28 days of age, compared to 3 days of age, the current values were 7.3% (Al5%) and 17.3% (Al10%), and it was confirmed that the electrical conductivity characteristics were slightly improved compared to AL0%.

In the AL15% and AL20% specimens containing a larger amount of coated aluminum, the currents for each curing day (3, 7, and 28 days) were measured to be 0.0827A, 0.0490A, 0.0215A, and 0.0824A, 0.0718A and 0.0716A, respectively. . The electrical conductivity at 28 days of age compared to 3 days of age was 26.0% (Al15%) and 86.9% (Al20%) levels, and it was confirmed that the electrical conductivity performance was greatly increased when 20% of aluminum was mixed.

In the AL25% test specimen containing the highest weight of aluminum, the currents for each curing day (3, 7, and 28 days) were measured to be 0.1150A, 0.0866A, and 0.0802A, and the current characteristics at 28 days compared to 3 days were 69.7% appeared as The absolute value of the measured current at 28 days of age was the highest in the AL25% specimen, but it was confirmed that the decrease rate was increased when compared to the 3-day curing.

In addition, the increase in electrical conductivity in the AL20%-AL25% section was insignificant compared to the AL15%-AL20% section. From the results, it is thought that the electrical conductivity of the mortar improves as the amount of aluminum mixed increases, and it was confirmed that the mortar had a fairly high level of electrical conductivity when mixed with 20% and 25% aluminum. In addition, when 20% of aluminum is mixed, it is judged that the improvement of electrical conductivity is the greatest.

On the other hand, the electrical resistance value increased along with the decrease in the current measured value for each specimen according to the curing period, and the change of the corresponding data is shown in the graph of [Fig. 5] (b).

The slope of the graph was found to be large in the order of the decrease rate of the measured current at 28 days of age compared to 3 days, and it was confirmed that the electrical resistance of the AL0% specimen with the lowest measured current value was the highest. The electrical resistance values according to the curing period of the AL0% specimen were 729Ω·m, 2,295Ω·m, and 7,368Ω·m for 3, 7, and 28 days of age, respectively. It showed a very high increase rate of 1010.5%.

The AL5% specimen showed electrical resistance values of 409Ω·m, 1157Ω·m, and 5600Ω·m at 3, 7, and 28 days, respectively, and the electrical resistance at 28 days was 1368.0% compared to 3 days, the highest rate of increase was shown.

Subsequently, the electrical resistance values for each age of the AL10% specimen were measured to be 331Ω·m, 707Ω·m, and 1918Ω·m, respectively. showed an increase rate.

In addition, the AL15% specimen had electrical resistance values of 169Ω·m, 286Ω·m, and 651Ω·m by age, and the electrical resistance at 28 days compared to 3 days was lowered to 384.7%.

In the case of the AL20% specimen with the greatest improvement in electrical conductivity, the electrical resistance values for each age were 0Ω·m, 195Ω·m, and 196Ω·m. The increase rate of electrical resistance was very insignificant at 115.1%.

Lastly, in AL25% containing the highest weight of aluminum, the electrical resistance values for each age were 122Ω·m, 162Ω·m, and 175Ω·m, which increased by 143.4% at 28 days compared to 3 days. The absolute value of electrical resistance of the specimen decreased slightly compared to AL20%, and the increase rate increased compared to AL20%, but the difference was insignificant.

[Fig. 6] is a graph showing the comparison of current values measured for 28 days of each specimen. Based on the AL25% specimen with the highest mixing amount of aluminum pieces, the aluminum pieces content of the AL0% to AL25% specimens are 0wt%, 20wt%, 40wt%, 60wt%, 80wt%, and 100wt%, respectively.

However, the degree of improvement in electrical conductivity is not directly proportional to the amount of aluminum mixed, and the slope of the graph also shows a large change in a specific section. It is estimated that the electrical conductivity does not increase or decrease in a certain width according to the amount of aluminum mixed, and the electrical conductivity is greatly improved when a certain threshold value is exceeded. In addition, in the subsequent section, the change amount of the measured current according to the increase of the mixing amount shows a decreasing trend. It is presumed that there exists a minimum condition in which sufficient distribution of the conductive material and an internal structure are formed to facilitate charge transfer.

[Fig. 7] is a graph showing the change in the compressive strength of specimens according to age according to the aluminum content. The compressive strength of the AL0% specimens showed the highest values at 3, 7, and 28 days of age, and the decrease in compressive strength increased in the order of AL5%, AL10%, AL15%, AL20% and AL25% specimens.

The compressive strength at 3, 7, and 28 days of age of the AL0% specimen was measured to be 31.6 MPa, 36.4 MPa, and 45.2 MPa, respectively.

The compressive strength at 3, 7, and 28 days of age of the AL5% specimen was measured to be 31.02 MPa, 35.07 MPa, and 43.80 MPa, respectively.

The compressive strength at 3, 7, and 28 days of age of the AL10% specimen was measured to be 29.8 MPa, 33.0 MPa, and 40.1 MPa, respectively.

The compressive strength of the AL15% specimen at 3, 7, and 28 days of age was measured to be 29.20 MPa, 33.00 MPa, and 38.71 MPa, respectively.

The compressive strength of the AL20% specimen at 3, 7, and 28 days of age was measured to be 28.6 MPa, 32.1 MPa, and 38.9 MPa, respectively.

The compressive strength of the AL25% specimen at 3, 7, and 28 days of age was measured to be 26.22 MPa, 29.23 MPa, and 34.05 MPa, respectively, indicating that the AL25% specimen had the lowest compressive strength.

In the case of compressive strength at 3 days of age, the AL5% specimen and the AL25% specimen were 98.2% and 94.2% compared to the AL0% specimen, and the AL15% specimen and the AL20% specimen were confirmed to be 92.4% and 90.4% compared to the AL0% specimen, respectively. In addition, the AL25% specimen with the highest amount of aluminum mixed showed the largest difference at 83% compared to the AL0% specimen.

In the case of compressive strength at 7 days of age, the AL5% and AL10% specimens are 96.3% and 90.7% compared to the AL0% specimen, and the AL15%, AL20%, and AL25% specimens are reduced to 90.7%, 88.3%, and 80.3% compared to the AL0% specimen. It was confirmed that the reduction rate was increased compared to the compressive strength at 3 days of age.

In addition, in the case of compressive strength at 28 days of age, the AL5% specimen and AL10% specimen were 97.0% and 88.9% compared to AL0%, and the ratios of 85.7%, 83.2%, and 75.4% were obtained in the order of AL15%, AL20%, and AL25% specimen. AL25% showed the highest reduction rate.

As a result, the decrease in compressive strength showed a tendency to increase as the amount of aluminum mixed increased, and it was confirmed that the decrease in compressive strength was the largest in the aluminum AL25% specimen.

These results are presumed to be due to the increased amount of mixing water to compensate for the decrease in workability as the aluminum mixing amount increases, and the influence of the aluminum pieces and coating solution in the mortar. As the mixing amount of the plate-shaped aluminum pieces increases, it acts as a factor that prevents sliding between cement particles, which leads to deterioration of workability. Therefore, it is essential to increase the amount of mixing water in order to secure workability suitable for molding, and the resulting surplus water also increases, resulting in a decrease in strength. In addition, since the aluminum piece is coarse compared to other materials of the mortar composition, it is expected to interfere with the densification of the mortar and cause a decrease in strength. In addition, it is considered that the coating solution remaining on the surface of the aluminum piece wraps the surface of the cement particles during the mortar mixing process and reduces the reactivity. As a result, it is presumed that the decrease in the hydration reaction occurred and the decrease in compressive strength increased with the lapse of curing days.

The above test results are summarized as follows.

The expansion ratio of the mortar specimen mixed with the uncoated aluminum piece was 112.6%, whereas the expansion ratio of the mortar specimen mixed with the coated aluminum piece was 100.8%. %, 20-50% rosin, and 5-15% surfactant, the reaction between aluminum and cement reactants (Ca(OH) ₂ ) is controlled by coating with a coating solution.

When 100V was applied to the mortar mixed with coated aluminum, the highest currents of 0.0716A and 0.0802A were measured in AL20% and AL25% specimens based on 28-day curing. The deviation of the measured current values between the AL15% and AL20% specimens was the largest, and the deviation of the measured current values between the AL20% and AL25% specimens decreased significantly.

The electrical resistance of each specimen showed a lower value as the measured current increased, and the resistance values of the AL20% and AL25% specimens with the highest current measured at 28 days of age were 196Ω·m and 175Ω·m, respectively. didn't

The compressive strength of each specimen decreased as the content of coated aluminum increased, and the 28-day compressive strengths of the AL20% and AL25% specimens showing the highest electrical conductivity were 38.9 MPa and 34.05 MPa, respectively, with a compressive strength of 45.2 MPa. was decreased to a level of 83.2% and 75.4% compared to the expressed AL0% test specimen.

As the mixing amount of coated aluminum increases, the electrical conductivity improves, but the compressive strength characteristic continuously decreases. It is thought to be the result of decreased hydration reaction due to the surface coating of cement particles.

Although the difference in electrical conductivity between the AL20% and AL25% specimens with the best electrical conductivity properties was not large, the reduction in compressive strength was the largest in the AL25% specimen, and the compressive strength of the AL25% specimen by age was also significantly different from that of the AL20% specimen. was confirmed, the range of 20-25 wt% of coating aluminum seems to be the most appropriate compared to cement, and excessive use of more than that is judged to be inefficient.

[Table 3] below summarizes the results of measuring the temperature change when 100V voltage is applied to each specimen cured for 28 days for 1 hour. The width of the temperature rise appeared in a similar manner to the above-described change in electrical conductivity. In particular, the temperature change of the AL15% and AL20% specimens increased from 5.7°C to 16.8°C, showing a sharp rise close to 300%.

In the above, the physical properties and effects of the composition of the present invention have been reviewed through the test examples, but the present invention will not be limited to the above test examples, and some modifications and changes within the scope without departing from the technical spirit of the present invention would say this is possible.

Not applicable

Claims (4)

A cement-based conductive composition in which foaming and expansion by aluminum is controlled by mixing 20-25 parts by weight of aluminum pieces coated with a surface to 100 parts by weight of cement.
In claim 1,
The aluminum piece is a cement-based conductive composition, characterized in that the aluminum can is cut into a square with a width of 2 to 4 mm and a length of 2 to 4 mm.
In claim 1 or 2,
The aluminum piece is a cement-based conductive composition, characterized in that it is coated with a coating solution consisting of 20 to 70 wt% of vegetable oil, 20 to 50 wt% of rosin, and 5 to 15 wt% of a surfactant.
In claim 3,
The coating treatment is
Cement, characterized in that the aluminum piece is maintained in a state of being precipitated in the coating solution at 15 to 25° C. for 2 hours or more, and after removing the aluminum piece from the coating solution, it is dried at 100° C. for 24 hours or more. based conductive composition.

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