KR102170359B1 - Fine-aggregate Modified-asphalt composition and construction method using the same - Google Patents

Abstract

The present invention a fine-grained modified asphalt mixture which includes a modified asphalt binder and fine aggregate. The modified asphalt binder comprises: 0.5-3.5 wt% of ethylene vinyl acetate-adhesive resin (EVA-AR); 0.5-2.5 wt% of styrene-butadiene-styrene (SBS); 1.5-4.5 wt% of low-density polyethylene (LDPE); and a remainder consisting of asphalt. The fine-grained modified asphalt mixture is applied to pedestrian-friendly impact relief asphalt concrete paving for pedestrian safety and preparation for an aging society by being paved on a sidewalk and a bicycle road.

Description

Fine-aggregate Modified-asphalt composition and construction method using the same}

The present invention relates to a modified asphalt mixture, and more particularly, to a fine-grained modified asphalt mixture suitable for construction on a sidewalk or bicycle road, and a construction method of a buffer asphalt concrete having a fine surface using the same.

Herein, background art related to the present disclosure is provided, and these do not necessarily mean known art.

Modified asphalt is an improvement in the properties of asphalt to improve durability, and can be classified according to the modification method or production method. The classification according to the modification method can be classified into polymer modified asphalt, additive modified asphalt, and chemical catalyst asphalt, and the classification according to the production method includes pre-mixing and plant-mixing. Can be distinguished.

Asphalt concrete pavement is a paving method used for more than 90% of roads worldwide due to its characteristics such as excellent riding comfort, excellent ice making performance, and ease of repair, and has flexibility with an elastic modulus of 10% compared to cement concrete pavement.

However, the above pavement method is mainly used for roadway pavement, and most of the pavement for sidewalks uses concrete, high-pressure blocks, sidewalk blocks, etc. (official term: concrete plates for sidewalks). There are many problems with walking due to the occurrence of defects and truncation.

In addition, in general, the maximum coarse aggregate dimension and fine aggregate ratio of the asphalt mixture are closely related to the workability and performance of the asphalt mixture.

The larger the maximum size of the coarse aggregate or the smaller the fine aggregate ratio, the higher the fluid resistance, which increases the resistance to plastic deformation, increases the stiffness, and has an economic advantage because the optimal asphalt content decreases, but the crack resistance decreases, and during production and installation. There is a disadvantage of increasing the possibility of material separation of the asphalt mixture.

On the contrary, the smaller the maximum size of the coarse aggregate or the higher the fine aggregate ratio, the less material separation of the asphalt mixture during construction and the increase in crack resistance, but there are disadvantages that the resistance to plastic deformation decreases and the optimum asphalt content increases.

The present invention is a fine-aggregate modified-asphalt (FAMA) mixture that can greatly alleviate excellent flatness and fine surface and walking impact energy by adding modifying components to general asphalt and adjusting the particle size and maximum dimensions of aggregate And it is intended to provide a buffered asphalt concrete paved using the same to apply to the pavement (low-volume road) limited vehicle operation such as sidewalks and bicycle roads.

In particular, this pavement not only relieves joint shock, but also reduces the risk of fracture by absorbing shock in the event of a fall, and provides a pedestrian-friendly pavement that can greatly reduce abrasion when falling because the fine surface is softer and softer than conventional asphalt pavement or concrete board for sidewalks. Is to do.

However, the objects of the present invention are not limited to the above-mentioned objects, and other objects that are not mentioned will be clearly understood by those skilled in the art from the following description.

The present invention includes a modified asphalt binder and a fine aggregate, wherein the modified asphalt binder is 0.5 to 2.5 wt% of an EVA-based adhesive resin, 0.5 to 2.5 wt% of styrene-butadiene-styrene (SBS), and low-density polyethylene (LDPE) It provides a finely modified asphalt mixture, characterized in that it comprises 1.5 to 4.5 wt% and the balance asphalt.

In addition, the fine aggregate is characterized in that it comprises a fine aggregate with a maximum dimension of 5 mm or less.

In addition, the fine aggregate is characterized in that it contains 90 to 95wt% based on the total weight of the fine-modified asphalt mixture.

In addition, the present invention provides an asphalt concrete prepared by heating and mixing and compacting the finely modified asphalt mixture.

In addition, the asphalt concrete is characterized by having a PG70-22 grade, a deformation strength (S _D ) of 2.7 MPa or more, and an indirect tensile strength (ITS) of 0.6 MPa or more.

The fine-grained modified asphalt mixture according to the present invention exhibits a sufficient value in terms of strength such as deformation strength and indirect tensile strength and excellent moisture resistance.In particular, in terms of shock absorption, it shows a shock absorption rate greater than 30% compared to a concrete plate for sidewalks. Promenades, roads within the complex, small roads with low traffic (including back alleys), back roads, bicycle roads, and rural roads, etc., provide a suitable effect to be applied to asphalt concrete pavement for pedestrian safety and pedestrian-friendly impact relief in preparation for an aging society. .

FIG. 1 shows an image comparing the surface condition of the buffer asphalt concrete trial plant surface and the block pavement of a fine surface using the fine-modified asphalt mixture according to the present invention.
Figure 2 shows an equipment and method for measuring the deformation strength of the buffered asphalt concrete manufactured according to an embodiment of the present invention.
Figure 3 shows the indirect tensile strength measuring equipment of the buffer asphalt concrete manufactured according to an embodiment of the present invention.
Figure 4 shows a method of measuring the impact absorption characteristics of the buffer asphalt concrete manufactured according to an embodiment of the present invention.

All technical and scientific terms used in the present specification have the same meaning as commonly understood by those of ordinary skill in the art unless otherwise stated. Also throughout the specification and claims, unless otherwise stated, the term "comprise, comprises, comprising" means to include the recited object, step or group of objects, and steps, and any other It is not used to exclude objects, steps, or groups of objects or steps.

Before describing the present invention in detail below, it is understood that the terms used in the present specification are for describing specific embodiments and are not intended to limit the scope of the present invention, which is limited only by the scope of the appended claims. shall.

Meanwhile, various embodiments of the present invention may be combined with any other embodiments unless there is a clear opposite point. Any feature indicated to be particularly preferred or advantageous may be combined with any other feature and features indicated to be preferred or advantageous. Hereinafter, embodiments of the present invention and effects thereof will be described with reference to the accompanying drawings.

The fine-grained modified asphalt mixture according to an embodiment of the present invention includes a modified asphalt binder and a fine-grained aggregate, at the time of construction PG70-22 grade, deformation strength (S _D ) 2.7 MPa or more (based on road base), indirect tensile strength ( ITS) Provides asphalt concrete that can be suitably used for sidewalks and bicycle lanes with more than 0.6 MPa (based on road base).

The grade of asphalt is expressed as PG XX-YY, where XX is the high temperature grade and the highest temperature of the asphalt pavement, -YY is the low temperature grade and the lowest temperature of the asphalt pavement. Therefore, XX represents the resistance to plastic deformation at high temperatures, and -YY represents the resistance to cracking at low temperatures.

The modified asphalt binder is an Ethylene Vinyl Acetate-based adhesive resin (hereinafter referred to as EVA-AR) 0.5 to 2.5 wt%, SBS (styrene-butadiene-styrene) 0.5 to 2.5 wt%, LDPE (low-density polyethylene) 1.5 To 4.5 wt% and the balance of asphalt. Here, as the asphalt, general asphalt of PG64-22 grade is used, and EVA-AR, which is a modified PE, is used in addition to general LDPE along with SBS to improve the bonding between artificial rubber and ethylene material.

The EVA-AR is used having the following physical properties and properties.

When comparing the performance according to the content of each component in consideration of performance and economy, it is preferable to include 0.5 to 2.5 wt% of EVA-AR, 0.5 to 1.5 wt% of SBS, and 1.5 to 3.5 wt% of LDPE, more preferably Preferably, it is preferable to include 1.5 to 2.5 wt% of EVA-AR, 0.5 to 1.5 wt% of SBS, and 1.5 to 2.5 wt% of LDPE.

For the fine aggregate, a fine aggregate having a maximum dimension of 5 mm or less is used. The fine aggregate is mixed including 90 to 95 wt% based on the total weight of the modified asphalt mixture.

In general, the maximum coarse aggregate dimension and fine aggregate ratio of an asphalt mixture are closely related to the workability and performance of the asphalt mixture.

The larger the maximum size of the coarse aggregate or the smaller the fine aggregate ratio is, the higher the fluid resistance is, the higher the resistance to plastic deformation, and the lower the optimal asphalt content has an economic advantage, but the crack resistance is lowered and the asphalt mixture is There is a disadvantage that the possibility of material separation increases.

On the contrary, the smaller the maximum size of the coarse aggregate or the higher the fine aggregate ratio, the less material separation of the asphalt mixture during construction and the increase in crack resistance, but the resistance to plastic deformation decreases and the optimal asphalt content increases. The present invention has high resistance to plastic deformation (deformation strength), even though the asphalt mixture is composed of fine aggregates only, and the optimum asphalt content (OAC) is not as high as 8.0% or less.

In addition, the fine-modified asphalt mixture according to the present invention may further include a filling material such as 0.5 to 1.5 wt% of limestone powder, hydrated lime (HL), and recovered dust of the total mixture weight. Preferably, it reduces the sensitivity to moisture to reduce the peeling of asphalt and aggregate, reduces the oxidation of asphalt to lower aging, slightly increases the stiffness of asphalt to lower plastic deformation, and reduces the growth rate of microcracks to crack It is recommended to use slaked lime in terms of increasing resistance.

In addition, by adding 3 to 5 wt% of the color pigment based on the total weight of the fine-modified asphalt mixture, it is possible to provide asphalt concrete pavement of various colors.

The fine-modified asphalt mixture according to the present invention is hot-mixed at 160 to 180°C of the modified asphalt binder and fine aggregate, and after short-term aging (STA) for 50 to 70 minutes at 160 to 170°C. It is made of asphalt concrete by compacting 75 times with a gyratory compactor.

The manufactured asphalt concrete satisfies PG70-22 grade, deformation strength (S _D ) 2.7 MPa or more, indirect tensile strength (ITS) 0.6 MPa or more, and is excellent in moisture resistance and shock absorption, so it is a sidewalk, promenade, road in the complex, and traffic volume. This small road (including back alleys), back roads, bicycle roads, and rural roads, etc., are suitable for pedestrian safety and pedestrian-friendly impact relief (buffering) asphalt concrete pavement.

The specific method of construction using the fine-modified asphalt mixture is a tidying step of arranging the target surface to be constructed, a mixing step of mixing the fine-modified asphalt mixture, and heating and mixing the mixed fine-modified asphalt mixture at 160 to 180°C. (Hot-mix) a heating mixing step of completely mixing each other, a laying step of laying the composition on the cleaned target surface, a compaction step of compacting 75 times with a gyratory compactor, and the compaction It includes a curing step of curing after the step is completed.

Fig. 1 shows an image comparing the surface condition of the buffer asphalt concrete trial plant surface and the block pavement of a fine surface using the fine-modified asphalt mixture according to the present invention, and it is confirmed that snow melts more rapidly compared to the sidewalk block pavement. I can.

Example

Using general asphalt (PG64-22), a modified asphalt binder was prepared in the formulation as shown in Table 1 below, and the prepared modified asphalt binder and fine aggregate with a maximum dimension of 5 mm or less (#4 sieve pass) were at 170°C. The asphalt concrete specimen was prepared by hot-mixing, short-term aging (STA) at 165° C. for 1 hour, and then compacting 75 times with a gyratory compactor. However, when preparing the mixture, 10 kg of hydrated lime (HL) per ton was added excluding the filler, which is 1% of the total weight of the mixture.

The measurement results of the performance grade of the prepared samples are shown in Table 1 below. The optimal content ranking was determined in the order in which the sum of the deviations for the intermediate value (HT:73°C/LT:-15°C) of the corresponding grade (PG70-22) and the upper grade (PG76-28) was the least.

Binder
designation Polymer (wt %) Performance grade (℃) Priority SBS EVA-AR LDPE High Temp. Low Temp. F112 One One 2 71.0 -14.1 4 F113 One One 3 73.9 -14.4 2 F114 One One 4 76.5 -14.5 5 F122 One 2 2 74.8 -15.2 One F123 One 2 3 76.7 -15.4 6 F212 2 One 2 75.2 -14.7 3 F213 2 One 3 77.0 -15.3 7

As shown in Table 1, it was confirmed that F113 and F122 samples containing 0.5 to 2.5 wt% of EVA-AR, 0.5 to 1.5 wt% of SBS, and 1.5 to 3.5 wt% of LDPE satisfies the PG grade stably and also satisfies the economy. In particular, it was confirmed that the F122 sample containing 0.5 to 1.5 wt% of SBS, 1.5 to 2.5 wt% of EVA-AR, and 1.5 to 2.5 wt% of LDPE was the most optimal content.

Experimental example

(1) Deformation strength (S _D ) measurement

Deformation strength (S _D ) is a test method developed to simply measure the resistance to plastic deformation occurring in asphalt concrete. In the S _D test, a test specimen with a porosity of 3±0.5% prepared with the optimum asphalt content determined through the formulation design is immersed in water at 60°C for 30 minutes to reach 60°C to the inside, and this test method is called Kim Test. . Through years of research, this test method was verified to have a very high correlation with the characteristics of plastic deformation occurring in common road pavements, and was included as a standard for mixing asphalt mixtures by the Ministry of Land, Infrastructure and Transport (Ministry of Land, Infrastructure and Transport 2017).

)을 읽어 [식 1]에 대입하여 계산한다. 도 2에 나타낸 것과 같이 장비를 이용하여 수직 정 하중을 가하여(도 2, (a)) 최대하중과 이때의 수직변위를 곡선으로부터 얻으며(도 2, (b)), 한 종류의 혼합물 당 3개 평균값을 강도 치로 사용하였다. 본 발명에 따른 공시체의 변형강도 시험세팅 이미지를 도 2, (c)에 나타내었다. S _D is the maximum load (P) in the load-deformation curve obtained by applying a load at 30㎜/min vertically to a specimen heated to 60℃ similar to the asphalt pavement temperature in the summer midday and the vertical deformation pressed from the surface at this time (

) And substitute it into [Equation 1] to calculate. As shown in Fig. 2, by applying a vertical static load using equipment (Fig. 2, (a)), the maximum load and the vertical displacement at this time are obtained from the curve (Fig. 2, (b)), and three per type of mixture The average value was used as the intensity value. The image of the deformation strength test setting of the specimen according to the present invention is shown in Figs.

[Equation 1]

= 최대하중에서 수직 변형 값(㎜)이다.)(Where, S _D = deformation strength (MPa), P = maximum load (N),

= Vertical deformation value (mm) at maximum load.)

(2) Indirect tensile strength (ITS) measurement

Tensile strength is a widely used characteristic value to predict the occurrence of cracks in asphalt pavement. Mixtures that can withstand high tensile stress before failure will have better resistance to cracking than mixtures that do not.

Here, for measuring indirect tensile strength with a specimen with a diameter of 100 mm, a specimen with a porosity of 3±0.5% was placed in a thermostat at 25°C for 4 hours and then taken out, and a load was applied at a rate of 50 mm/min in the same manner as shown in FIG. The maximum load (P) was obtained by substituting in [Equation 2].

[Equation 2]

(Here, ITS = indirect tensile strength (MPa), P = maximum load (N), D = specimen diameter (mm), t = specimen thickness (mm).)

(3) Deformation strength and thin point tensile strength measurement result

Among the above samples, the contents of the F122 and F113 samples of priority 1 and 2 were added to the red samples (F122R, F113R) and the black samples (F122B, F113B) prepared by adding a red pigment. For the deformation strength and tensile strength measured by the above method are shown in Table 2 below. The optimum asphalt content (OAC) that satisfies the air void ratio of 2-5% and the strain strength (S _D ) of 2.35 MPa or more was determined.

Color Designation OAC
(%) Air Void
(%) S _D
(MPa) ITS
(MPa) Black Control (PG64-22) 7.5 2.5 3.06 0.72 F113B 7.7 2.5 3.41 0.81 F122B 7.8 3.0 3.50 0.88 Red F113R 8.0 2.4 3.52 0.84 F122R 8.0 2.9 3.57 0.84

Deformation strength test result of FAMA mixture As shown in Table 2 above, it is 3.4 MPa or more, which is significantly higher than the deformation strength of Control mixture using general asphalt, and is higher than 2.7 MPa, which is the standard for roads in the Ministry of Land, and You can see that it is improved.

As shown in Table 2 above, the results of the indirect tensile strength test of the FAMA mixture are significantly higher than 0.6 MPa, which is the standard for roads (bases) of the Ministry of Land, Infrastructure and Transport as shown in Table 2. It can be seen that the resistance is improved.

(4) Moisture resistance measurement and result

Asphalt mixture is prone to peeling by water. In particular, in Korea, granite, which is a hydrophilic aggregate, is widely used as aggregate for road pavement, and there is concern about stripping and partial damage (porthole, etc.) during melting during the rainy season and winter (Kwangwoo Kim 2015). Therefore, resistance to moisture was measured for the developed FAMA mixture.

As a commonly used method for evaluating moisture resistance, there is a method of measuring tensile strength ratio (TSR) (KS F 2398). In this method, the porosity of the test specimen was adjusted, the target porosity was determined to be 5±0.5%, and the moisture resistance characteristics were measured.

Two sets (6 specimens) of circular specimens having a porosity of 5±0.5% of the FAMA mixture were prepared. One of the two prepared specimens was dried at 25℃, the other was wet in a 60℃ water bath for 24 hours, and then treated at 25℃ for at least 2 hours before the test. Was performed. Indirect tensile strength in dry and wet conditions was measured, and the tensile strength ratio was calculated by applying to [Equation 3]. The results are shown in Table 3.

[Equation 3]

(Here, TSR = tensile strength ratio, ITS _wet = indirect tensile strength (MPa) after immersion treatment at 60℃ for 24 hours, ITS _Dry = dry (no treatment) indirect tensile strength (MPa) of the specimen.)

Color Designation OAC
(%) Air Void
(%) ITS
(MPa) TSR Black Control (PG64-22) 7.5 5.4 Dry 0.62 0.726 5.5 Wet 0.45 F113B 7.7 5.4 Dry 0.67 0.896 5.2 Wet 0.60 F122B 7.8 5.6 Dry 0.72 0.903 5.2 Wet 0.65 Red F113R 8.0 5.6 Dry 0.71 0.915 5.2 Wet 0.65 F122R 8.0 5.6 Dry 0.70 0.914 5.2 Wet 0.64

As shown in Table 3 above, the tensile strength ratio (TSR) of the general mixture (Control) before and after water immersion treatment is 0.8 or less, which is the standard for general asphalt concrete of the Ministry of Land, Infrastructure and Transport, whereas the TSR of the FAMA mixture according to the present invention is excellent at an average of 0.9 or more Appeared. Accordingly, when the FAMA mixture according to the present invention is used, it is determined that damage due to moisture penetration will be greatly reduced even in the summer rainy season or the sea ice season. Among the two mixture samples, F122 was found to be somewhat better in the binder test value and in the mixture property evaluation, and the impact absorption characteristics were measured for F122.

(5) Measurement and result of impact absorption characteristics

Shock absorbed energy refers to the total amount of energy absorbed by an object when an object is subjected to an impact. In general, the impact test measures the amount of energy absorbed by an object after applying an impact to a test object. Impact energy is affected by temperature and humidity, and when an impact is applied to an object, 90% of the energy received from the impact surface is concentrated on the surface of the object.

Recently, the Korea Institute of Construction Technology has attempted to develop a standard pedestrian model for the design of pedestrian facilities in urban areas in preparation for an ultra-aged society (No Chang-gyun et al., 2018). According to the survey, even though facilities that meet the standards are provided, the satisfaction level of the pedestrian environment is relatively lower than in the past. This is because the current sidewalk pavement does not match the pedestrian behavior of the elderly and the poor. Therefore, it means that sidewalk flatness and impact mitigation should be considered when designing and constructing sidewalk pavement.

PE로 환산하였다. Therefore, in the present invention, as shown in Fig. 4, as shown in Fig. 4, a drop ball test is performed. (ⓐ general asphalt pavement for roadways, ⓑ general concrete pavement, ⓒ concrete plates for sidewalks (sidewalk blocks)) Absorption test was performed and the value was obtained by [Equation 4.] The initial position of the ball was H _o = 1m (1,000mm), and the difference from the initial height of 1,000mm was measured by measuring the height H ₁ that bounced first after free fall. Absorbed energy

Converted to PE.

[Equation 4]

ΔPE = WH ₀ -WH ₁

(Where, W: ball weight (2.423N), ΔPE: impact energy absorption amount (N-mm), H ₀ , H ₁ : initial position of the ball and the first repulsion height (mm).)

Table 4 shows by comparing the impact energy absorption rates of various road pavement materials and curb stones.

Designation 1 ^st Rebound height (mm)
(Average of 5 times) Potential energy after drop
(ΔPE: N.mm) Energy absorption
(Nm) Impact absorption rate compared to sidewalk concrete plate (%) F122B 377 913 1,510 128% F122R 360 872 1,551 132% Asphalt pavement 479 1,161 1,262 107% Concrete pavement 518 1,255 1,168 99% Sidewalk concrete plate 514 1,245 1,178 100% boundary stone 728 1,764 659 56% Initial potential energy= 2.3226N*1,000mm=2,423 N.mm
(mg=1kg=9.8N, m=237g=2.3226N, h=1000mm)

Since the FAMA mixture according to the present invention is a mixture designed suitable for delivery pavement, a concrete plate for sidewalks was used as a standard (100%), and the shock absorption rates of each material were compared. Looking at the results, the FAMA mixture pavement according to the present invention showed a higher absorption rate of 30% on average compared to the concrete plate for sidewalks. This is 23% higher than that of general roadway asphalt pavement, and is expected to greatly absorb the impact of falls when walking, and it is expected to greatly reduce damage such as stiffness and scratches.

Features, structures, effects, and the like illustrated in each of the above-described embodiments can be combined or modified for other embodiments by a person having ordinary knowledge in the field to which the embodiments belong. Therefore, contents related to such combinations and modifications should be construed as being included in the scope of the present invention.

Claims (5)

Asphalt concrete formed of a fine-modified asphalt mixture containing a modified asphalt binder and a fine aggregate,
The modified asphalt binder is an EVA-based adhesive resin (Ethylene Vinyl Acetate-Adhesive Resin) 1.5 to 2.5 wt%, SBS (styrene-butadiene-styrene) 0.5 to 1.5 wt%, LDPE (low-density polyethylene) 1.5 to 2.5 wt% And the remainder of asphalt,
The EVA-based adhesive resin has a melt index (ASTM D1238) of 2 to 3 g/10min at 190°C, a density (ASTM D1505) of 0.94 g/cm ³ , and a yield point stress (ASTM D638) of 96 kgf/cm ² , The elongation (ASTM D638) is 500% or more, the flexural modulus (ASTM D790) is 3200 kgf/cm ² , the Izod impact strength (ASTM D256) at 23°C is 57 kgf·cm/cm, and the hardness (ASTM D2240 ) Is 41 Shore D, Vicat softening point (ASTM D1525) is 75 ℃, and adhesive strength (ASTM D903) is 6 kgf/cm ²
In the asphalt concrete, the modified asphalt binder and the fine aggregate are hot-mixed at 160 to 180°C, and short-term aging (STA) for 50 to 70 minutes at 160 to 170°C, followed by a gyratory compactor. ), obtained by committing 75 times,
The asphalt concrete, characterized in that the tensile strength ratio (TSR) before and after water immersion treatment is 0.9 or more.
The method of claim 1,
Asphalt concrete, characterized in that the fine aggregate comprises a fine aggregate having a maximum dimension of 5 mm or less.
The method of claim 1,
Asphalt concrete, characterized in that the fine aggregate is contained 90 to 95wt% based on the total weight of the fine modified asphalt mixture.
delete The method of claim 1,
The asphalt concrete is PG70-22 grade, deformation strength (Deformation strength: S _D ) 2.7 MPa or more, indirect tensile strength (ITS) Asphalt concrete, characterized in that at least 0.6 MPa.

Images