RECYCLED ASPHALT CONCRETE WITH MINIMIZED AMOUNT OF FLAT AND ELONGATED PARTICLES, AND MANUFACTURING METHOD THEREFOR

Abstract

The present invention relates to recycled asphalt concrete and a manufacturing method therefor and, more specifically, to recycled and regenerated asphalt concrete and a manufacturing method therefor, which minimizes the amount of flat and elongated particles included in aggregates used as materials for asphalt concrete, thereby increasing the quality of the asphalt concrete to first grade (the amount of the flat and elongated particles is less than 10%) and increasing the durability of the asphalt concrete.

Claims

1. A recycled asphalt concrete with a minimized amount of flat and elongated particles, wherein the recycled asphalt concrete consists of 50 to 55 wt % of natural aggregates and recycled aggregates, 35 to 40 wt % of sand, 2.9 to 5 wt % of a filler, and 4.8 to 10 wt % of new asphalt containing PCM so that the amount of the flat and elongated particles is less than 10 wt % of the entire aggregates, wherein the PCM consists of 5 to 10 wt % of a recycling additive consisting of one of paraffinic and aromatic mixed oils or malten oil, Baca C oil (containing 10 to 20 wt % of asphalt and 15 to 30 wt % of malten oil), 5 to 10 wt % of a modified additive, 1 to 5 wt % of a dispersant, and 1 to 5 wt % of p-toluene sulfonic acid (p-TSA) as a peel reducing agent with respect to the new asphalt.

2. A recycled asphalt concrete with a minimized amount of flat and elongated particles, wherein the recycled asphalt concrete consists of 50 to 55 wt % of natural aggregates and recycled aggregates, 35 to 40 wt % of sand, 2.9 to 5 wt % of a filler, and 4.8 to 10 wt % of new asphalt containing PCM so that the amount of the flat and elongated particles is less than 10 wt % of the entire aggregates, wherein the PCM is constituted by mixing 5 to 10 wt % of a recycling additive consisting of one of paraffinic and aromatic mixed oils or malten oil, Baca C oil (containing 10 to 20 wt % of asphalt and 15 to 30 wt % of malten oil), 5 to 10 wt % of a modified additive, 1 to 5 wt % of a dispersant, and 1 to 5 wt % of p-toluene sulfonic acid (p-TSA) as a peel reducing agent with respect to the new asphalt.

Description

BEST MODE

[0013] Generally, in a manufacturing process for asphalt concrete, aggregates are heated in a dryer, sorted, measured, and transferred from a cold bin loaded with the aggregates to a mixer through a conveyer and then mixed with asphalt, PCM, and the like in a mixer.

[0014] In this case, a high rate of flat and elongated particles is contained in the mixed coarse aggregates, and as a means for preventing the mixing, crushing and abrasion processes of aggregates are performed.

[0015] The crushing process of the aggregates is performed through a crusher and the crusher makes a particle shape of the aggregate supplied to an aggregate inlet to be close to a circle through a process of hitting with a blade and colliding with a wall.

[0016] As described above, the crushed aggregates are transferred through the conveyer by passing through the crusher and aggregate screens are installed step by step to sort the aggregates according to sizes of the aggregates. That is, aggregates with particle sizes of less than 13 mm pass through a 13 mm screen net and the aggregates with particle sizes of more than 13 mm are filtered by the screen.

[0017] The PCM is added to the entire asphalt concrete using the sorted aggregates to satisfy the mechanical property of the asphalt concrete and the used PCM consists of four ingredients.

[0018] That is, the present invention provides recycled asphalt concrete with a minimized amount of flat and elongated particles which consist of 50 to 55 wt % of natural aggregates and recycled aggregates, 35 to 40 wt % of sand, 2.9 to 5 wt % of a filler, and 4.8 to 10 wt% of new asphalt containing PCM so that the amount of the flat and elongated particles is less than 10 wt% of the entire aggregates.

[0019] The PCM may be contained with 10.0 to 30.0 wt % in the new asphalt and these ingredients and contents are as follows.

[0020] 1) The content of the recycling additive is 5.0 to 10.0 wt % in the new asphalt and the used recycling additive consists of one of paraffinic and aromatic mixed oils or malten oil, Baca C oil (containing 10 to 20 wt % of asphalt and 15 to 30 wt % of malten oil).

[0021] 2) The content of the modified additive is 5.0 to 10.0 wt % in the new asphalt and a configuration of the used modified additive consists of one of waste tire fine powder, low density polyethylene (LLDPE) fine powder, SBS, SBR, SBI, SEBS, and EPDM or a mixture thereof.

[0022] 3) The content of the dispersant is 1 to 5 wt % in the new asphalt and the used dispersant consists of one of PE Wax, PP Wax, and Amide Wax or a mixture thereof.

[0023] 4) The content of the peel reducing agent is 1.0 to 5.0 wt % in the new asphalt and the used peel reducing agent is a material matched with cations on the aggregate surface and consists of one of quaternary ammonium or p-TSA in order to maximize adhesion with the aggregates.

[0024] Table 1 illustrates a PCM ingredient composition table according to Example of the present invention.

TABLE-US-00001 TABLE 1 Classification PCM-1 PCM-2 PCM-3 PCM-4 PCM-5 PCM-6 A(5-10%) 3.0% 5.0% 5.0% 10.0%  10.0% 10.0% B(5-10%) 3.0% 5.0% 10.0%  5.0% 10.0% 10.0% C(1-5%) 1.0% 3.0% 3.0% 3.0%  3.0%  5.0% D(1-5%) 1.0% 2.0% 2.0% 2.0%  2.0%  5.0% Total 8.0% 15.0%  20.0%  20.0%  25.0% 30.0% A: Recycling additive B: Modified additive: SBS C: Dispersant: PE wax D: Peel reducing agent: p-TSA

[0025] That is, first, first grade natural aggregates and recycled aggregates (13 mm), sand, a filler, and new asphalt containing PCM were mixed in a hot bin heated at 130 to 150° C. through a mixing design and a mixing design composition table thereof is illustrated in Table 2 below.

TABLE-US-00002 TABLE 2 Comparative Comparative Example Example Example Example Example Example Classification Example 1 Example 2 1 2 3 4 5 6 13 mm natural 276.0 257.0 aggregates Sand 390.0 409.0 13 mm recycled 257.0 257.0 aggregates Filler 29.0 29.0 New asphalt 48.0 48.0 44.1 40.8 38.4 38.4 36.0 33.6 PCM-1(12%) 3.9 PCM-2(15%) 7.2 PCM-3(20%) 9.6 PCM-4(20%) 9.6 PCM-5(25%) 12.0 PCM-6(30%) 14.4 Total 1,000.0

[0026] Table 3 below illustrates a mixing design composition table without adding PCM in comparison with Example according to the present invention.

TABLE-US-00003 TABLE 3 Mixed Mixed Material Used ratio amount mixed material (%) Calculation basis (kg) ratio (%) 13 mm 29 1000*(1-A/100)*B/100 276 27.6 natural aggregates Sand 41 1000*(1-A/100)*B/100 390 39 13 mm 25.9 1000*(1-A/100)*B/100 257 25.7 recycled aggregates 1.1 Filler 3 1000*(1-A/100)*B/100 29 2.9 New 4.8 1000*(A/100) 48 4.8 asphalt Total 1000 100.0 Note Calculation basis legend: A = AP ratio (%) B = Aggregates ratio per bin (%) * Asphalt content = New asphalt + Old asphalt included in recycled aggregates 4.8 + 1.1 = 5.9%

[0027] Table 4 below illustrates a mixing design composition table of Example 3 according to the present invention.

TABLE-US-00004 TABLE 4 Material Mixed Mixed mixed Used ratio amount ratio material (%) Calculation basis (kg) (%) 13 mm 27 1000*(1-A/100)*B/100 257 25.7 natural aggregates Sand 43 1000*(1-A/100)*B/100 409 40.9 13 mm 25.9 1000*(1-A/100)*B/100 257 25.7 recycled aggregates 1.1 Filler 3 1000*(1-A/100)*B/100 29 2.9 New 3.84 1000*(A/100) 42.2 4.22 asphalt PCM-1 0.96 5.8 0.58 Total 1000 100.0 Note Calculation basis legend: A = AP + PCM ratio (%) B = Aggregates ratio per bin (%) * Asphalt content = New asphalt + PCM + Old asphalt included in recycled aggregates 4.22 + 0.58 + 1.1 = 5.9%

[0028] Table 5 below is a property table illustrated by comparing properties in Comparative

[0029] Examples and Examples according to the present invention.

TABLE-US-00005 TABLE 5 Comparative Comparative Example Example Example Example Example Example Classification Example 1 Example 2 1 2 3 4 5 6 Stability (N) 11,312 11,942 13,538 13,860 14,205 13,950 14,305 14,950 6,000 or more Flow value 36 33 31 28 27 28 24 23 (1/100 cm) 20~40 Porosity (%) 4.7 4.6 4.4 4.4 4.4 4.3 4.3 4.3 3~6 Saturation (%) 74.1 74.5 75.4 75.4 75.4 75.2 75.8 75.8 70~85 Density (g/) 2.355 2.358 2.362 2.363 2.363 2.364 2.364 2.365 — Indirect tensile 1.3 1.4 1.5 1.5 1.6 1.5 1.6 1.6 strength (N/) 0.8 or more Tensile strength 0.8 0.9 1.0 1.0 1.1 1.0 1.1 1.2 index after soaking 0.7 or more Toughness (N*) 10,359 10,864 11,104 11,140 11,210 11,150 11,270 11,360 8,000 or more Asphalt amount (%) 5.9 5.9 5.9 5.9 5.9 5.9 5.9 5.9 4.5-7.0

[0030] Comparative Example 1 illustrates physical properties for asphalt concrete without using first grade aggregates, Comparative Example 2 illustrates physical properties of asphalt concrete in which only new asphalt is added in the mixture of first grade natural aggregates and recycled aggregate, and Examples 1 to 6 illustrate physical properties of asphalt concrete adding PCM.

[0031] First, Comparative Examples 1 and 2 illustrate that stability and indirect tensile strength in comparison and a tensile strength index after soaking are also improved.

[0032] In terms of stability, as compared with Examples 1 to 3, in Examples 5 and 6, the recycling additive of the PCM is increased and the content of the modified additive is increased, and thus the physical properties are excellent.

[0033] As the content of the dispersant (PE wax) is increased, the physical property values are good, and even though the peel reducing agent is increased, there is no numerical increase when the content is a predetermined amount or more.

[0034] First, when an ingredient A (a recycling additive) of the PCM is less than 3.0%, the ingredient A does not satisfy a role of a restorative and when the content is 10.0% or more, a very soft phenomenon occurs and thus it is preferred that the optimum use amount is 0.5%.

[0035] Second, when an ingredient B (a modified additive, SBS) of the PCM is less than 3.0%, the ingredient B does not satisfy a role of a modifier and when the content is 10.0% or more, viscosity is too high and thus it is preferable that the optimal use amount is 10.0%.

[0036] Third, when an ingredient C (a dispersant, PE-wax) of the PCM is less than 1.0%, the ingredient C does not satisfy a role of a dispersant and when the content is more than 5.0%, the viscosity is too deteriorated and thus it is preferred that the optimal use amount is 3.0%.

[0037] Fourth, when an ingredient D (a peel reducing agent, p-TSA:p-toluene sulfonic acid) of the PCM is less than 1.0%, the ingredient D does not satisfy a role of suppressing peeling of aggregates and when the content is more than 2.0%, the effect is similar and thus it is preferred that the optimal use amount is 2.0%.

[0038] As a result of summarizing the physical properties, the physical properties in Example 3 were the most excellent.