KR100919493B1 - Recycled Aggregates coated with Water-based Water Repellent Agent and Application to a Concrete Structure - Google Patents

Abstract

The present invention relates to a circulating aggregate coated with an aqueous water repellent and a concrete composition using the same, the purpose of which is coated with an aqueous water repellent to improve the performance of the circulating coarse aggregate to be used as a concrete aggregate by coating the water repellent agent on the circulating coarse aggregate To provide recycled aggregates.

The present invention is to immerse in water-based water repellent for 24 hours and to dry it for more than 24 hours in air condition to coat the water-repellent agent in the circulating aggregate, excellent even when replacing the coated coarse aggregate with natural aggregate when mixing concrete Compressive strength and durability are provided.

Description

Recycled Aggregates coated with Water-based Water Repellent Agent and Application to a Concrete Structure}

The present invention relates to the improvement of the performance of the recycled aggregate coated with an aqueous water repellent and a concrete composition using the same, by coating the surface of the recycled aggregate with an aqueous water repellent, by minimizing the voids and cracks of the recycled aggregate, the absorption rate of the recycled aggregate is fundamentally reduced The present invention relates to a recycled aggregate coated with an aqueous water repellent and a concrete composition using the same, which can produce a concrete composition having excellent physical properties.

In general, construction waste refers to waste building materials generated at the time of demolition of various buildings, and mostly reinforcement and cement lumps, such as waste concrete, waste wood, and waste plastics.

These construction wastes are incinerated according to a legal procedure, and non-combustible wastes such as waste concrete are crushed and recycled into recycled aggregates.

As described above, the recycled aggregate is removed from impurities such as iron and plastics contained in the waste concrete, and then the waste concrete mass is crushed by using a compression crushing or lot mill, ball mill, tube mill, etc. Manufactured by a dry treatment method to separate, separate, or remove sludge using wind power,

After crushing the waste concrete to a certain size, it is crushed by using one of these types such as tube mill, drum type peeler, rod mill, ball mill for the purpose of peeling mortar from aggregate surface in the wet state, and treated with water on the screen. It is manufactured by a wet treatment method for classifying sludge and fine aggregates.

However, the recycled aggregate produced by the above-mentioned dry treatment method is not suitable for using the recycled aggregate produced alone due to low efficiency of peeling and classification as the aggregate for concrete.

The recycled aggregate produced by the wet method is superior to the recycled aggregate produced by the dry method, but this is also unsuitable for use alone as a concrete aggregate.

In other words, the conventional recycled aggregate is used for concrete aggregates due to factors such as voids, cracks, and water absorption, and thus, structural problems are caused by problems such as reduced concrete strength, reduced durability, increased dry shrinkage, and mixed water management compared to natural aggregates. For non-structural use, it was used for road pavement bases and asphalt concrete.

The present invention is to solve the problems described above to utilize the high value of the recycled aggregate, its purpose is to cover the water-repellent agent to the circulating coarse aggregate to improve the performance of the coarse aggregate aggregate to be used as concrete aggregate It is to provide a coated recycled aggregate.

Still another object of the present invention is to provide a circulating aggregate coated with an aqueous water repellent which can have excellent compressive strength and durability even when natural aggregate for concrete is replaced with a circulating coarse aggregate, and a concrete composition using the same.

The present invention is to utilize the coating treatment system to reduce the absorption rate by filling the pores and cracks developed in the interior and exterior of the circulating aggregate to immerse in an aqueous water repellent for 24 hours and to dry it for more than 24 hours in air condition to the aqueous aggregate Is to cover.

At this time, the water-based water repellent is a silane-based water-repellent agent, the liquid type, the color is milky white, the density is about 0.96 (g / cm3).

In addition, the circulating aggregate before coating was used as three kinds of circulating aggregate, crushed and sieved aggregate.

As described above, the present invention has a filling effect of voids and cracks in the recycled aggregates by coating an aqueous water repellent agent on the recycled aggregates, thereby fundamentally lowering the absorption rate of the recycled aggregates, thereby improving physical properties so that the aggregates can be used as concrete aggregates. At the same time, it is possible to meet the slump and air volume regulations when concrete mixing and improve strength and durability.

In addition, the present invention is to coat the water-repellent agent to the recycled aggregate by dipping, it is easy to manufacture, mass production is possible, can reduce the production cost and cost, entangled with each other when the coating by dipping There is no effect such as sticking.

1 is an exemplary block diagram showing a method for manufacturing a coated circulation aggregate according to the present invention.

Figure 2 is an exemplary view showing the slump value according to the uncoated, coated recycled aggregate replacement rate when the water / cement ratio is 45%

Figure 3 is an exemplary view showing the slump value according to the uncoated, coated recycled aggregate replacement rate when the water / cement ratio 50%

4 is an exemplary view showing a slump value according to the uncoated and coated recycled aggregate replacement ratio when the water / cement ratio is 55%

5 is an exemplary view showing the amount of air according to the uncoated, coated circulation aggregate replacement rate when the water / cement ratio is 45%

6 is an exemplary view showing the amount of air according to the uncoated, coated circulation aggregate replacement rate when the water / cement ratio is 50%

7 is an exemplary view showing the amount of air according to the uncoated, coated circulation aggregate replacement rate when the water / cement ratio is 55%

8 is an exemplary view showing the compressive strength according to the uncoated, coated recycled aggregate replacement rate when the water / cement ratio is 45%

9 is an exemplary view showing the compressive strength according to the uncoated, coated recycled aggregate replacement rate when the water / cement ratio is 50%

10 is an exemplary view showing the compressive strength according to the uncoated, coated recycled aggregate replacement rate when the water / cement ratio is 55%

11 is an exemplary view showing the bending strength according to the uncoated, coated recycled aggregate replacement rate when the water / cement ratio 45%

12 is an exemplary view showing the bending strength according to the uncoated, coated recycled aggregate replacement rate when the water / cement ratio is 50%

13 is an exemplary view showing the bending strength according to the uncoated, coated recycled aggregate replacement rate when the water / cement ratio is 55%

14 and 15 is a photographic example showing the current state and depth of concrete neutralization according to the present invention

Figure 16 is an exemplary view showing the neutralization depth according to the uncoated, coated recycled aggregate replacement rate when the water / cement ratio 45%

Figure 17 is an exemplary view showing the neutralization depth according to the uncoated, coated recycled aggregate replacement rate when the water / cement ratio 50%

18 is an illustration showing the neutralization depth according to the uncoated, coated recycled aggregate replacement rate when the water / cement ratio is 55%

19 is an exemplary view showing the dry weight loss according to the uncoated, coated recycled aggregate substitution rate when the water / cement ratio is 45%

20 is an exemplary view showing the dry weight loss according to the uncoated, coated recycled aggregate replacement rate when the water / cement ratio is 50%

21 is an exemplary view showing the dry weight loss according to the uncoated, coated recycled aggregate substitution rate when the water / cement ratio is 55%

Figure 1 shows a block example showing a method for producing a coated circulation aggregate according to the present invention, the present invention is immersed in the water-repellent agent circulating coarse aggregate 20 to 28 hours, preferably 24 hours and 24 in the air condition It is made to dry for about 24 to 72 hours or more, and to coat an aqueous water repellent agent on a circulating aggregate.

In the present invention, the silane-based water-repellent agent was coated on the circulating aggregate. The reason for this was to penetrate into the cracks and pores of the concrete surface layer to secure a constant depth of penetration, and at the same time to form a watertight film on the inner surface of the cracks and voids to protect and reinforce the concept. This is because it is introduced water repellent.

In addition, the silane-based water repellent and oil-based water repellent were tested at the same time, and the performance of the recycled aggregate coated with the silane-based water repellent was more excellent.In the recycled aggregate coated with the silane-based water repellent, the recycled aggregate coated with the silane-based water repellent was Unlike the entanglement between aggregates during coating, the production was not easy and the productivity was reduced. Thus, the silane-based water repellent was used to coat the recycled aggregate.

The circulating coarse aggregate before the coating means three kinds of crushed aggregates and crushed aggregates, and such circulating coarse aggregates have physical properties as shown in Table 1 below.

Table 1

The circulating coarse aggregate is manufactured by the dry treatment method that removes impurities such as iron materials and plastics contained in the waste concrete, and then simply crushes and sorts and separates crushed materials by particle size using a screen, and the size of the coarse aggregate is a construction standard. The maximum dimension passed by the weight ratio of aggregates presented in the specification was applied to 25 mm.

The water-based water repellent is a silane-based water repellent, liquid type, and has a density of about 0.96 (g / cm 3).

In addition, the aqueous water-repellent agent is composed of n-octyltriethoxysila-ne, amino group-containing siloxane (Aminofunctional Siloxane) and water as an example.

Hereinafter, the present invention will be described in detail by way of examples.

Example 1

Three types of circulating aggregates were immersed in a milky white liquid silane-based water-repellent agent having a density of 0.96 (g / cm 3) for 24 hours, and dried again in a dry state for 24 hours to prepare a circulating coarse aggregate coated with an aqueous water-repellent agent. The physical properties of the coarse aggregate coated with an aqueous water repellent were measured. The results are shown in [Table 2].

[Table 2]

At this time, absorption rate is KS F 2503 (specific gravity and absorption test of coarse aggregate), moisture content is KS F 2550 (measurement method of moisture content and surface yield of aggregate), wear rate is KS F 2508 (wear test method of coarse aggregate by Los Angeles testing machine) ), The stability was tested by KS F 2507 (aggregate stability test method) and the particle shape determination performance rate by KS F 2505 (unit volume weight and porosity test method of aggregate).

As shown in [Table 2], the circulating coarse aggregate coated with the water-repellent agent is the regulation of the circulating coarse aggregate produced from the waste concrete (KS F 2573: 2006 circulating aggregate for concrete)-a dry density of 2.5 (g / cm 3) or more, With water absorption less than 3%, wear rate less than 40%, performance rate more than 55%, and stability less than 12%, it was found that the water-repellent coating circulating coarse aggregate was tested to satisfy all regulations except dry density. However, 05000 concrete construction 2.1.2 aggregate of the construction standard specification (2006) 1) According to the proviso clause, it can be used when it is confirmed that the concrete has a certain quality if the dry density is more than 2.4 (g / cm3). According to the provisions, it can be seen that the general concrete can be used for the water-repellent coating circulating coarse aggregate.

Example 2

The concrete composition was blended as shown in Table 3 below using the circular coarse aggregate prepared as in Example 1. At this time, the cement was used Portland cement, the fine aggregate among the natural aggregates used Hadongsan river sand, the coarse aggregates used Jinhaesan crushed stone gravel.

Table 3

Example 3

For the concrete composition blended by Example 2, the slump and the amount of air were measured, and the results are shown in Table 4 below and FIGS. 2 to 7. At this time, the target slump of the concrete composition was set to 18 ± 2 cm, the slump test method was measured by KS F 2421 (test method of concrete slump). In addition, the target air volume was set to 4.5 ± 1.5%, the air volume test method was measured by KS F 2421 (air content test method by the pressure method of the concrete concrete).

Table 4

Figure 2 is a slump according to the uncoated, coated recycled aggregate replacement rate when the water / cement ratio 45%, Figure 3 is a slump according to the uncoated, coated recycled aggregate replacement rate when the water / cement ratio 50%, Figure 4 is water It shows the slump according to the replacement rate of uncoated and coated circulating aggregate when the ratio of cement / cement ratio is 55%, and the experiment of the slump value according to the uncoated and coated circulating coarse aggregate substitution rate by water / cement ratio, The slump value of the concrete showed a slump value similar to that of the plain (concrete manufactured using only plain aggregate), and was in the range suitable for the target slump specification.

However, in the case of using uncoated cyclic coarse aggregate, the decrease in slump was increased as the cyclic coarse aggregate replacement rate was increased.

This is judged to be due to the absorption rate of uncoated and coated circulating coarse aggregate, and when analyzing the experimental results of the slump, it can be seen that the general concrete can be utilized for the circulating coarse aggregate of aqueous coating.

FIG. 5 shows the air amount according to the uncoated and coated recycled aggregate replacement rate when the water / cement ratio is 45%, FIG. 6 is the air amount according to the uncoated and coated recycled aggregate replacement ratio when the water / cement ratio is 50%, FIG. When the ratio of uncoated and coated circulating aggregates is 55%, the air volume according to the uncoated and coated circulating aggregate replacement rate is tested. The air volume of concrete shows air volume similar to that of plain and is in a range suitable for the target air volume regulation. However, in the case of using uncoated cyclic coarse aggregate, the air volume increased as the circulating coarse aggregate replacement rate increased. This is judged by the filling effect of the pores and cracks of the aggregate itself according to the coating of the water-repellent agent of the circulating coarse aggregate, and when analyzing the experimental results of the air volume, it can be seen that the general concrete can be used for the circulating coarse aggregate of the aqueous coating.

Example 4

For the concrete composition blended by Example 2, after forming the specimen, the compressive strength and the flexural strength thereof were measured, and the results are shown in Table 5 below and FIGS. 8 to 13. The compressive strength is measured by measuring the width and height of three specimens and three heights of specimens manufactured according to the provisions of KS F 2405 (concrete compressive strength test method) and KS F 2408 (concrete flexural strength test method). The average load was measured and the length was measured. The maximum load leading to failure was measured by the simple beam three-point test method, and the flexural strength was calculated by the following equation.

f _b = Pl / bh ² (f _b : flexural strength (MPa), P: maximum load (N) indicated by the tester, l: span (mm), b: butterfly (mm) of fracture cross section, h: height of fracture cross section) (Mm))

Table 5

FIG. 8 shows compressive strength of uncoated and coated recycled aggregates at 45% water / cement ratio, and FIG. 9 shows compressive strength of uncoated and coated recycled aggregates at 50% water / cement ratio. Shows the compressive strength of uncoated and coated recycled aggregate at 55% water / cement ratio, showing the highest compressive strength at 45% water / cement ratio, and decreased as the water / cement ratio increased. .

In general, concrete manufactured using natural sand and circulating coarse aggregate is known to exhibit 15-30% lower compressive strength than ordinary concrete, but concrete mixed with aqueous coating circulating coarse aggregate is uncoated circulating coarse aggregate in the present invention. It can be seen that the strength improvement effect is apparent compared to the case using. The high level of compressive strength of aqueous coated circulating coarse aggregate concrete compared to uncoated cyclic coarse aggregate concrete is believed to be due to the filling and absorption of the voids and cracks in the aggregate itself. In addition, the comparison of water-coated cyclic coarse aggregate concrete and plain showed that when the replacement rate of water-coated cyclic coarse aggregate was 50%, it was similar to or higher than the plain strength and similar or slightly decreased when it was 100%. Therefore, when analyzing the experimental results of the concrete compressive strength, it can be seen that the general concrete utilization of the aqueous coating circulation coarse aggregate is possible.

FIG. 11 shows the bending strength according to the uncoated and coated recycled aggregate replacement rate when the water / cement ratio is 45%, FIG. 12 shows the flexural strength according to the uncoated and coated recycled aggregate substitution rate when the water / cement ratio is 50%, and FIG. The flexural strength of uncoated and coated circulating aggregates at 55% / cement ratio is shown. In the case of flexural strength, as the water / cement ratio increases with the compressive strength, the strength decreases, but there is no obvious trend. At the early age of 3 days, both the aqueous coated circulation aggregate and the uncoated recycled aggregate showed similar strength compared to the plain, but the water coated cement aggregate was somewhat lower than the plain except for the water / cement ratio of 50%. The strength is shown. This is believed to be due to the adhesion between aggregate and cement paste due to aqueous coating at early age, and tends to be similar to 1/5 to 1/8 of general concrete flexural strength / compressive strength. It can be seen that.

Example 5

For the concrete composition blended in Example 2, after forming the test body, the neutralization depth thereof was measured, and the results are shown in FIGS. 14 to 18.

At this time, the test specimen is to be measured by cutting the 10cm × 10cm × 40cm to 10cm length when the test age is measured, but for the convenience of the test to prepare a specimen of 10 × 20cm for each compounding from the beginning It was. The test bodies were cured in air for 1 day after underwater curing for 4 weeks. This is to reduce the water effect of the test subjects on the neutralization, and after putting the curing in the neutralization test apparatus, the degree of neutralization penetration was measured after 4 weeks.

Neutralization test currently has no relevant standards in Korea, and accelerated neutralization tests were conducted under conditions of 20 ± 2 ° C, 60 ± 5% relative humidity, and 5 ± 0.2% carbon dioxide concentration of JIS A 1153 in Japan. In order to ensure that the test specimens were spaced at least 2 cm apart.

The measurement was carried out after cutting the test specimen at a predetermined age, and after spraying a 1% phenolphthalene solution, the distance from the concrete surface to the colored part was measured by 12 places and the average value was determined as the neutralization depth. .

14 and 15 is a photographic illustration showing the current state and depth of concrete neutralization according to the present invention, Figure 16 is a neutralization depth according to the uncoated, coated recycled aggregate replacement rate when the water / cement ratio 45%, Figure 17 is water The neutralization depth according to the uncoated and coated circulating aggregate substitution rate at 50% / cement ratio, and FIG. 18 shows the neutralization depth according to the uncoated and coated circulating aggregate substitution rate at 55% water / cement ratio. Neutralization depth was found to be significantly decreased and the resistance to neutralization was significantly reduced when coarse circulating aggregate was used than when plain and bare circulating aggregate were used under cement ratio.

As the coated circular coarse aggregate maintains the state of continuous coating even after concrete production, it is expected to be effective in improving the long-term durability, and the resistance to neutralization of the aqueous coated circular coarse aggregate has been shown to be excellent. It can be seen that the concrete can be used.

Example 6

For the concrete composition blended by Example 2, after the specimen was formed, the dry weight reduction amount thereof was measured and the results are shown in Table 6 below and FIGS. 19 to 21. At this time, the dry weight loss test measures the weight of the specimens which have been cured under water for 28 days in a curing tank at 20 ± 3 ℃, and then changes the weights of the specimens every 8 hours until there is no weight loss in the 80 ± 5 ℃ drying furnace. Observed and dried.

Table 6

19 shows the dry weight loss according to the uncoated and coated circulating aggregate substitution rate when the water / cement ratio is 45%, and FIG. 20 shows the dry weight loss according to the uncoated and coated circulating aggregate substitution rate when the water / cement ratio is 50%, 21 shows the dry weight loss according to the uncoated and coated recycled aggregate replacement rate when the water / cement ratio is 55%, and in the case of coated recycled coarse aggregate, the dry weight decrease is less at all conditions compared to the uncoated recycled coarse aggregate. It was measured to be slightly higher than Plain. In particular, the dry weight loss similar to plain was measured under the condition that the substitution rate of aqueous coated circulating aggregate was 50% and the water / cement ratio was 55%. It is expected that it will be effective to improve the long-term durability, so it can be seen that the general concrete utilization of the aqueous coating circulation coarse aggregate is possible.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

Claims (6)

In the circular coarse aggregate for concrete addition, The circulating coarse aggregate is coated with a silane-based water repellent, Circulating coarse aggregate before coating is 3 kinds of circulating aggregate, Circulating coarse aggregate coated with an aqueous water repellent is circulating aggregate coated with an aqueous water repellent, characterized in that formed to have the physical properties as shown in the following [Table 2]. [Table 2] delete The method according to claim 1; The circulating aggregate before coating the circulating aggregate coated with an aqueous water repellent, characterized in that it has the physical properties as shown in the following [Table 1]. Table 1 delete In the concrete composition which contains cement, water, sand, coarse aggregate, and fine aggregate; The coarse aggregate, It consists of a mixed aggregate of natural aggregates and circulating coarse aggregate coated with an aqueous water repellent, A water-based water repellent is coated on the three recycled aggregates of the following [Table 1] concrete composition using the recycled aggregate coated with the water-repellent agent, characterized in that consisting of a circular coarse aggregate having the physical properties as shown in the following [Table 2]. Table 1 [Table 2] The method according to claim 5; The mixed aggregate is a concrete composition using a circular aggregate coated with an aqueous water repellent, characterized in that the cyclic coarse aggregate coated with an aqueous water repellent is added to be replaced by 50 to 100%.