The objective of the study is to evaluate the performance of porous asphalt using waste recycled concrete material and explore the effect of adding Gilsonite to the mixture. As many as 90 Marshall specimens were prepared with varied asphalt content, percentage of Gilsonite as an additive, and proportioned recycled and virgin coarse aggregate. The test includes permeability capability and Marshall characteristics. The results showed that recycled concrete materials seem to have a potential use as aggregate in the hot mix asphalt, particularly on porous hot mix asphalt. Adding Gilsonite at ranges 8–10% improves the Marshall characteristic of the mix, particularly its stability, without decreasing significantly the permeability capability of the mix. The use of recycled materials tends to increase the asphalt content of the mix at about 1 to 2% higher. With stability reaching 750 kg, the hot mix recycled porous asphalt may be suitable for use in the local roads with medium vehicle load.
In the recent years, as the Indonesian economy improves, the need for additional infrastructure tends to increase. In most cities, areas which used to be residential ones have been converted into commercials. Many 2- or 3-story buildings mostly built in 1980s have been demolished and rebuilt into 8–12-story buildings, hence leaving a large amount of waste material as by-product of demolition.
In the same time, as the need for infrastructure to support the economic activities increases, many agricultural fields have also been converted into residential areas, hence decreasing the open land area. Consequently, the amount of rain water being infiltrated into underground has also decreased. ICPI [
Effect of built areas on the amount of water infiltration (ICPI, 2009).
These two phenomena need to be addressed in all aspects of civil infrastructures since in the long run it will affect the human life. As for the transportation infrastructure, the construction of roads should also consider these aspects, as part of the road sustainability. When waste materials are available in the area, they should be utilized as part of the construction materials. However, until recently, only few countries have implemented such concept [
Another potential application for sustainable highway system is the use of the porous pavement system. Porous pavement has been practiced since the 1960s in Europe for the construction of airport runway [
However, one of the disadvantages of porous asphalt pavement is its performance. Previous research showed that the Marshall stability of porous asphalt specimens usually fell below 500 kg. This is unfortunate since to be able to be used in the arterial or collector road systems, pavement should have Marshall stability at least 750 kg. Therefore, efforts should be pursued to increase the Marshall stability of the porous asphalt so that it can be applied on arterial or collector road systems.
Reviewing the nature of the porous asphalt, in which its strength and performance were influenced by the internal force among coarse material and the bonding contributed by asphalt, increasing the bonding capability of asphalt may improve the performance of the mixture. This can be done by adding additive to the mixture. Previous research by Ameri et al. [
Therefore, in this research, the effect of Gilsonite on the performance of porous asphalt using recycled concrete material was investigated to explore whether it contributes to the improvement of the mixture performance.
The objective of the study is to evaluate the performance of porous asphalt using waste recycled concrete material.
Figure
Steps of the research.
Asphalt used in this research was AC 60/70. This is the most commonly used asphalt in Indonesia with respect to weather and conditions. Tables
Properties of AC 60/70.
Number | Description | Unit | Specifications |
Test results | |
---|---|---|---|---|---|
Min | Max | ||||
1 | Penetration | mm | 60 | 79 | 61.778 |
2 | Softening point | °C | 48 | 58 | 49 |
3 | Ductility | mm | 100 | — | >1500 |
4 | Flash point | °C | 200 | — | 320 |
5 | Burning point | °C | 200 | — | 346 |
6 | Specific gravity | 1 | — | 1.061 |
Properties of asphalt AC 60/70 mixed with Gilsonite additive.
Number | Properties | Unit | AC 60/70 specifications | Gilsonite additive (%) | |||||
---|---|---|---|---|---|---|---|---|---|
Min | Max | 0 | 2 | 4 | 6 | 8 | |||
1 | Penetration | 0.1 mm | 60 | 79 | 62 | 53.4 | 45.8 | 44 | 41 |
2 | Softening point | °C | 48 | 58 | 54 | 56 | 57 | 61 | 65 |
3 | Flash point | °C | 100 | — | 321 | 336 | 342 | 342 | 342 |
Properties of Gilsonite HMA modifier grade [
Number | Properties | Values |
---|---|---|
1 | Softening point (ASTM E28-92) | 160–185°C |
2 | Ash (ASTM D-271-70 M) | ≤1.0% |
3 | Moisture (AGC method) | <0.5% |
4 | Penetration (25°C, 100 gm, 5 sec.) | 0 |
5 | Flash point (COC) | 316°C |
6 | Nitrogen | 3% |
7 | Sulfur | 0.3% |
8 | Specific gravity | 1.06 |
9 | Color in mass | Black |
Two coarse aggregates are used in the research: common and concrete waste recycled materials. Tables
Properties of regular coarse aggregate.
Number | Properties | Unit | Specifications |
Test results | Notes | |
---|---|---|---|---|---|---|
Min | Max | |||||
1 | Specific gravity | — | 2.5 | — | 2.642 | OK |
2 | SSD specific gravity | — | — | — | 2.690 | OK |
3 | Specific gravity | — | — | — | 2.776 | OK |
4 | Water absorption | % | — | 3 | 1.818 | OK |
5 | Los Angeles | % | — | 40 | 12.748 | OK |
6 | Impact value | % | — | 30 | 12.186 | OK |
Properties of concrete waste aggregate.
Number | Properties | Unit | Specifications |
Test results | Notes | |
---|---|---|---|---|---|---|
Min | Max | |||||
1 | Specific gravity | — | 2.5 | — | 2.45 | Not OK |
2 | SSD specific gravity | — | — | — | 2.56 | OK |
3 | Specific gravity | — | — | — | 2.74 | OK |
4 | Water absorption | % | — | 3 | 4.8 | Not OK |
5 | Los Angeles | % | — | 40 | 27.36 | OK |
6 | Impact value | % | — | 30 | 20.42 | OK |
Properties of fine aggregates.
Number | Properties | Unit | Specifications |
Test results | Notes | |
---|---|---|---|---|---|---|
Min | Max | |||||
1 | Specific gravity | — | 2.5 | — | 2.733 | OK |
2 | SSD specific gravity | — | 2.5 | — | 2.770 | OK |
3 | Specific gravity | — | — | — | 2.839 | OK |
4 | Water absorption | % | — | 3 | 1.359 | OK |
The common material was acquired from quarry commonly used in East Java, Indonesia, while the concrete waste was acquired from concrete testing by-products.
Before being used, the concrete waste was crushed using crusher to obtain the required gradation.
The fine aggregate was acquired from Lumajang, the largest sand quarry in East Java. As can be seen from the tables, the materials conform to the Indonesia specification, except the specific gravity and the water absorption of the waste materials, which have lower values than the specs.
Once the materials were tested, the next step was to prepare the Marshall specimens. The experimental design for this purpose is presented in Table
Proportion of the aggregate, asphalt content, and number of samples.
Common and recycled materials proportion (%) | Asphalt content (%) | ||||
---|---|---|---|---|---|
5 | 6 | 7 | 8 | 9 | |
Number of samples | |||||
100/0 | 3 | 3 | 3 | 3 | 3 |
80/20 | 3 | 3 | 3 | 3 | 3 |
60/40 | 3 | 3 | 3 | 3 | 3 |
40/60 | 3 | 3 | 3 | 3 | 3 |
20/80 | 3 | 3 | 3 | 3 | 3 |
0/100 | 3 | 3 | 3 | 3 | 3 |
90 Marshall specimens were prepared using proportioned coarse aggregate and asphalt content as shown in Table
All Marshall specimens were mixed at 145°C, following the standard procedure, except for those containing Gilsonite HMA modifier, which were heated to about 175°C, to ensure that Gilsonite mixes properly with asphalt. The compaction was conducted at 135°C.
The next step was to determine the optimum Gilsonite additive percentage when added to the mix. This was done by preparing the Marshall specimens using the optimum asphalt content obtained from the previous step and mixed with Gilsonite additive with proportion and number of samples as shown in Table
Design of experiment to obtain optimum Gilsonite content.
% Gilsonite additive | Number of samples |
---|---|
7% | 3 |
8% | 3 |
9% | 3 |
10% | 3 |
A falling head permeability test was conducted to measure the permeability capability of the mixture. The permeability capability is expressed in terms of permeability coefficient (
This test was conducted to determine the Marshall characteristics which includes stability, flow, voids in mineral aggregate (VMA) and void in the mix (VIM), and the optimum asphalt content. The specimens for the test were shown in Table
This test was conducted to determine the amount of optimum Gilsonite additive. The procedure follows the Marshall procedure as Marshall test stage 1 except that the amount of asphalt in the mix uses the optimum asphalt content obtained from Marshall test stage 1. The specimens for the test were shown in Table
The last step of the research was to analyze the results of the test and provide plausible analysis of the phenomenon.
Figures
Figure
Permeability coefficient (
Marshall stability of specimens (kg) at each asphalt content and coarse aggregate proportion.
Marshall flow of specimens (mm) at each asphalt content and coarse aggregate proportion.
Marshall VIM of specimens (%) at each asphalt content and coarse aggregate proportion.
Marshall VMA of specimens (%) at each asphalt content and coarse aggregate proportion.
Figures
Summary of optimum asphalt content and its Marshall characteristics.
Marshall characteristics | Coarse aggregate proportion | Australian specifications | |||||
---|---|---|---|---|---|---|---|
100/0 | 80/20 | 60/40 | 40/60 | 20/80 | 0/100 | ||
Optimum asphalt content | |||||||
7% | 7% | 8.5% | 7.5% | 7.5% | 7% | ||
VIM | 13.0 | 12.9 | 12.3 | 12.4 | 13.2 | 15.6 | 18%–25% |
Stability | 342.3 | 454.5 | 520.6 | 528.3 | 559.3 | 560.9 | >500 kg |
Flow | 3.1 | 3.4 | 3.5 | 3.8 | 3.9 | 4.2 | 2–6 mm |
MQ | 113.3 | 130.1 | 149.4 | 136.4 | 145.3 | 137.3 | <400 kg/mm |
As can be seen from Table
Another point that can be explained from the table is that none of the mixes meets the VIM requirement. As the Australian standard requires that the VIM should be in the range of 18 to 25%, all mixes fall below the range. The plausible explanation on this phenomenon is that higher asphalt content in the mix fills void, causing reduced void area.
Table
In order to increase the stability, one may need to add some additives, as previous researches have shown. This was accomplished by the Marshall test stage 2 as explained above. Using Table
Marshall characteristics at different percentage of Gilsonite additive.
Asphalt content | % recycled materials | % Gilsonite additive | VIM | Stability | Flow | MQ |
---|---|---|---|---|---|---|
7.5% | 100% | 7% | 20.0 | 653 | 5 | 131 |
21.0 | 707 | 5.5 | 129 | |||
21.6 | 623 | 4.5 | 138 | |||
8% | 22.3 | 718 | 5.5 | 130 | ||
21.5 | 675 | 5.8 | 116 | |||
19.8 | 621 | 5.8 | 107 | |||
9% | 20.6 | 868 | 5.4 | 161 | ||
21.9 | 771 | 5.5 | 140 | |||
21.0 | 825 | 4.2 | 196 | |||
10% | 20.3 | 707 | 5.6 | 126 | ||
20.3 | 743 | 5.6 | 133 | |||
21.8 | 686 | 5 | 137 |
Results of permeability test on specimens with Gilsonite additive.
Asphalt content | % recycled concrete | % Gilsonite | Permeability coefficient |
---|---|---|---|
7.5% | 100% | 7% | 0.41 |
0.35 | |||
0.36 | |||
8% | 0.40 | ||
0.42 | |||
0.44 | |||
9% | 0.31 | ||
0.34 | |||
0.34 | |||
10% | 0.31 | ||
0.36 | |||
0.30 |
An analysis of variance was performed to the data to determine the effect of adding Gilsonite to each Marshall characteristic. The summary of the analysis is presented in Table
Summary of effect of Gilsonite additive on the Marshall characteristics and permeability capability.
Marshall characteristics | Gilsonite effect | |
---|---|---|
|
Remarks | |
VIM | 0.937 | Not significant |
Stability | 0.007 | Significant |
Flow | 0.007 | Significant |
MQ | 0.032 | Significant |
As can be seen from Table
Using the standard procedure for Marshall analysis, it was found that the optimum Gilsonite content was 9%. Furthermore, the related Marshall characteristic is presented in Table
Effect of Gilsonite additive on Marshall characteristic.
Marshall characteristics | Test results at 9% Gilsonite | Specifications | Remarks |
---|---|---|---|
VIM | 21.2 | 18%–25% | OK |
Stability | 761 | >500 kg | OK |
Flow | 5.4 | 2–6 mm | OK |
MQ | 144 | <400 kg/mm | OK |
Permeability | 0.327 cm/sec | 0.2–0.5 cm/sec | OK |
Based on the above discussions, the following conclusions can be drawn: Recycled concrete materials seem to have a potent to be used as aggregate in the hot mix asphalt, particularly on porous hot mix asphalt. Adding Gilsonite additive at ranges 8–10% improves the Marshall characteristic of the mix, particularly its stability, without decreasing the permeability capability of the mix. The use of recycled materials tends to increase the asphalt content of the mix, from the range 5-6% to 7-8%. With stability reaching 750 kg, the hot mix recycled porous asphalt may be suitable for use in the local roads with medium vehicle load.
The authors declare that there is no conflict of interests regarding the publication of this paper.
The results presented in this paper are part of the research project funded by the Indonesian Ministry of Higher Education Research Fund. The authors would like to thank all the Minister that have provided the fund.