Evaluation of Split Mastic Asphalt Mixture Using Materials from Borneo

Ludfi Djakfar*, Yulvi Zaika, Aloysius Greg. Lake

Faculty of Engineering, University of Brawijaya, Malang, Jl M.T. Haryono 167 Malang, Indonesia

ABSTRACT

The purposes of this study are (1) Assessing the physical characteristics of the aggregate of Bulungan, Kutai and Banjar, and (2) Evaluating the performance of these local materials on split mastic asphalt (SMA) mixture using Marshall Characteristic and dynamic characteristics (resilient modulus).To achieve the above objectives, asphalt mixture samples have been prepared using materials from Banjar, Kutai and Bulungan. As many as 90 samples were prepared and tested to obtain its optimum asphalt content, Marshall characteristics, and resilient modulus.The results of the experiment showed that samples prepared from Banjar materials performed better than those Kutai and Bulungan in Marshall Characteristics. However, when reviewing their resilient modulus, the results were inconclusive since samples from Banjar materials did not perfomed better than the others. In addition, performance of mixtures prepared using Borneo local materials fell below those from Java. It can be concluded that materials from those three locations were not recommended to be used in stone mastic asphalt, which requires high performance materials. However, it still can be used for asphalt mixtures designed for use in local road in which heavy traffics do not dominate.

KEY WORDS: Split mastic asphalt, Bornoe local aggregate, Marshall test, indirect tensile test, resilient modulus.

INTRODUCTION

Constructing roads in Borneo has its own challenges. The materials for road construction, particularly for asphalt concrete mixtures are imported from other islands, since local materials tend to have lower performance. Relying on materials from outside the island will be costly, and will slow the speed of the government development programs. Therefore, there should be efforts to explore and seek local quarries that may be suitable for road construction. In the last decade, particularly after the enactment of Autonomy Act (UU No 32 1999), there has been a substantial change in the development of Borneo. After the government agrees to form new local governments/municipalities to speed up the development program in Borneo, the need for infrastructure increased substantially. Construction of new road network and maintenance the existing ones become essential to support the development. The existing condition, though, compared to other regions in Indonesia, Borneo is still far below in terms of its road infrastructures, as shown in Table 1. The accessibility index of Borneo, an index used to measure the degree of accessibility of a region, which is a function of length of road compared to the area of a region, is about 0,08, which is far below, say of Java which is 0,66. Constructing roads in Borneo, however, has its own challenges. The majority of the region consists of peat soil that requires special treatment before putting roadbed on it. The materials for road construction, particularly for asphalt concrete mixes are imported from other islands, since local materials tend to have lower performance. Other issues that need to be taken into consideration is the mining explorations that start flourishing in some areas will bring heavy load trucks to the area, either to transport the coals or to bring equipment for exploration. This activity should be taken into consideration, particularly when designing the asphalt concrete mixes.

*Corresponding Author: Dr. Ludfi Djakfar, Faculty of Engineering, University of Brawijaya, Malang, Jl M.T. Haryono 167 Malang, Indonesia.

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Table 1. Accessibility and Mobility Index on Major Islands in Indonesia. Island Length of Roads (km) Accessibility Mobility Index Toll National Province Regency Total Length Index (km / (Km/1000 km 2) population) Sumatra 43 10589 16398 99739 126769 0,28 2,62 Java 628 5119 9072 70838 85657 0,66 0,66 Bali 0 502 883 5576 6961 1,28 2,01 Nusa Tenggara 0 1875 4703 18031 24609 0,37 2,82 Kalimantan 0 5706 5543 31376 42625 0,08 3,25 Sulawesi 18 7082 7428 41404 55932 0,29 3,36 Maluku & Papua 0 3747 4652 21224 29623 0,06 5,91 Total 689 34620 48679 288188 372176 0,20 1,65

Relying on materials from outside the island will be costly, and will slow the speed of the government development programs. Therefore, there should be efforts to explore and seek local quarries that may be suitable for road construction. Quarry Database Study in Kalimantan [1] concluded that there is considerable potential quarry for road construction in Borneo. Regions that have considerable quarry that may meet requirements for asphalt concrete mixture is in the region Bulungan, Banjarbaru, and Kutai. Provious studies conducted to evaluate these local materials for use in asphalt mixes have come to unconclusive results. Research related to the performance of local materials for construction materials has been performed. Yamin [2] has evaluated the performance of local materials based on the parameters of the Marshall and has concluded that some material in East Kalimantan is good enough for road pavement materials, particularly for base materials. Wahyudianto, et al [3] conducted a study on the characteristics of materials at Pasir Regency, East Kalimantan, while Gunawan [4] conducted research material from Banjar district. The conclusion of their research is that the material from Borneo can be used for asphalt materials. These studies, however, examined only the performance of materials based on Marshall's parameters. With the introduction of pavement design techniques using a mechanistic-empirical method, where one of the characteristics of the material required is resilient modulus, it is necessary to do a more comprehensive evaluation of the asphalt mixtures using both Marshall Test and a dynamic test [5]. [6]. [7]. Another consideration that needs to be taken into account when designing asphalt mixtures in Borneo is the possibility of the roads to be loaded by heavy traffic due to mining exploration and other economic activities. For these kinds of loads, the split mastic asphalt (SMA) mixture may be a plausible alternative. SMA is a type of asphalt concrete mixes with coarse aggregate content of ± 70% and ± 11% filler. Tabel 2 and 3 showed a sample specification of SMA in Indonesia. It was first developed in Germany in 1960s.

Table 2. Gradation Requirements for SMA Mixtures Aggregate Gradation (% Pass filter) 12.50 mm 100 11.20 mm 90-100 8.00 mm 50-75 5.00 mm 30-50 2.00 mm 20-30 0.71 mm 13-25 0.25 mm 10-20 0.09 mm 8-13

Previous researches showed that the SMA mixture performed better to to deformation, had a high skid resistance and tended to be more durable, due to high asphalt content stabilized with cellulose fibers. These characteristics suit to serve heavy vehicles loads [8]. In Indonesia, researches on SMA mixtures have also been performed, such as by Pratiwi [9], Noerfadly et al., [10], Irwanto [11], and Astika [12]. All these studies, however, used aggregates from Java, which in general performe satisfactorily when used in asphalt mixtures. Considering the problems in Borneo and the potential use of SMA for heavy traffic loads, it seems necessary to evaluate the performance of local materials in Borneo for use in a split mastic asphalt mixture.

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Table 3. Requirements for Asphalt Concrete Mixtures by Bina Marga Mixture Properties Laston Toilet BC Base Asphalt Absorption (%) Max 1,2 The number of collisions per field 75 12 Voids in mix (%) Min 3,5 Max 5,5 Cavity in the aggregate (VMA)% Min 15 14 13 Cavity filled with asphalt (%) Min 65 63 60 Marshall Stability (kg) Min 800 1500 Max - - Melting mm) Min 3 5 Marshall Quotient (kg / mm) Min 250 300 Marshall Stabililtas remaining (%) after soaking 24 hours, Min 75 60 0 C Voids in mix (%) on bouncy density (refusal) Min 2,5

The purposes of this study are as follows: 1) Assessing the physical characteristics of the aggregate of Bulungan, Kutai and Banjar. 2) Evaluating the performance of these local materials on split mastic asphalt (SMA) mixture using Marshall Characteristic and dynamic characteristics (resilient modulus).

RESEARCH METHODS

The research was conducted with steps as follows:

1. Evaluate the charactteristics of the local materials asphalt used in the study. 2. Prepare the sample 3. Evaluate the sample using Marshall Criteria 4. Determine the optimum asphalt contents and their residual strength index (RSI) 5. Determine the resilient modulus of the mixture using the Indirect Tensile Strength.

The research was conducted at the Laboratory of Road Materials, Faculty of Engineering, University of Brawijaya, and Malang. The asphalt used in this study was AC 60/70 bitumen produced by Pertamina. To obtain the optimum asphalt content, the specimens were made at various asphalt contents of 4.5%, 5.5%, 6.5%, 7.5% and 8.5%. Schematically, the research design is shown in Figure 1 and Table 4.

Asphalt Content 4,5% (X1)

Marshall Test Indirect Tensile Test Asphalt Content 5,5% (X2) Stability (Y1) Flow (Y2) Vertical Force (Newton) OAC Asphalt Content VIM (Y3) Tensile Strain (Kpa) 6,5% (X3) VFA (Y4) Elastic Modulus (Mpa) VMA(Y5) Crack Width (mm) RSI (Y6) Asphalt Content 7,5% (X4)

Asphalt Content 8,5% (X5)

Figure 1. Schematic Design of the Research

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Table 4. Experimental Design

Material Variations Asphalt Contents Bulungan Kutai Row 4.5% 6 samples 6 samples 6 samples 5.5% 6 samples 6 samples 6 samples 6.5% 6 samples 6 samples 6 samples 7.5% 6 samples 6 samples 6 samples 8.5% 6 samples 6 samples 6 samples

Once the optimum asphalt content was obtained, the next step is to prepare specimens for both Marshall Test and the indirect tensile test to obtain the resilient mudulus of the samples. The test was conducted at the Road and Bridge Research Center, Bandung. RESULTS AND DISCUSSION 3.1 Material Characteristics

Tables 5 and 6 shows the results of the tests for aggregates and asphalt, respectively. Based on Table 5, it can be concluded that the material from these three sites are eligible to be used as material of the SMA mixture. In general, aggregates from Banjar seem to have better quality compared to those from Bulungan and Kutai, particularly when considering their wearing values.

3.2. Marshall Characteristics

Figure 2 shows the Marshall characteristics of the samples. This characteristic was obtained at the optimum asphalt content for each mixture. In general, material from Banjar has better performance compared with those from other sources, as can be seen from the Marshall stability and Flow. In addition, only specimens prepared from Banjar materials meet the requirement for SMA. The figure also shows that the Marshall stability of all samples generally are in the range between 650-900 kg, a bit low compared to mixtures prepared using Materials from Java, which may yield up to 1500 kg.

Table 5. Aggregate Test Results from Bulungan, Kutai, and Banjar SPECIFICATIONS No. DESCRIPTION Unit Bulungan Kutai Banjar Min Max COARSE AGGREGATE 1. Dry Density (Bulk) - 2,5 - 3.89 3:13 2:58 2. Surface Dry Specific Gravity - - - 3.90 3:16 2.62 (SSD) 3. Pseudo Density (Apparent) - - - 3.91 3:21 2.68 4. Water Absorption % - 3 00:12 0.79 1:47 5. Wear aggregate % - 40 30 23:54 23:48 FINE AGGREGATE 1. Dry Density (Bulk) % 2.5 - 2:57 2:50 2:56 2. Surface Dry Specific Gravity - - - 2:59 2:49 2:57 (SSD) 3. Pseudo Density (Apparent) - 2.5 2.62 2:55 2:59

4. Water Absorption % - 3 0.77 1:56 00:42

Table 6. Results of Asphalt Testing

Specification No. DESCRIPTION Testing Methods Unit Results MIN MAX 1. Penetration (25 0 C, 5 seconds) SNI 06-2546-1991 0.1 mm 60 79 66,9 2. Softening Point (Ring & Ball) SNI 06-2434-1991 o C 48 58 48,5 3. Flash point SNI 06-2433-1991 o C 200 - 327 4. Daktalitas SNI 06-2432-1991 Cm 100 - > 150 5. Type weight SNI 06-2441-1991 - 1 - 1,0641

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3.3. Residual Strength Index Residual strength index is used to assess the durability potential of split mastic asphalt mix. This index is obtained from the Marshall immersion test. Table 7 shows the residual strength index from the specimens. The specification of Split Mastic Asphalt mixture requires that its value shall be greater than 75%. As can be seen from the table, specimens from all regions meet the requirement.

3.4. Dynamic Load Characteristics

Table 8 shows the test results of the Indirect Tensile test. It can be seen that the specimens made from Banjar material has the lowest resilient modulus value. These findings are interesting since it contradicts with results from Marshall characteristics, in which speciment from Banjar material had better characteristics compared to others, say, in their stability value. A mix with high stability value does not warrant that it will have a high resilient modulus. What the results show, therefore, is that stability alone cannot be used as the indicator to conclude the performance of a mix.

Figure 2. Marshall Characteristics of the Samples

Table 7. Residual Strength Index Source of OAC Stability (kg) Losing Stability Residual Index Material (%) Standard IKS (Kg) (%) (%) Bulungan 7,2 688,5 528,7 159,8 23,2 76,8 Kutai 6,8 730,1 615,1 114,9 15,7 84,3 Banjar 6,3 877,9 691,7 186,2 21,2 78,8

Table 8. Indirect Tensile Modulus Test Results Test Specimens OAC Thickness Force (kN) Tensile Stress Resilient Modulus (Mm) (MPa) (MPa) Bulungan 1 7,155 62,0 1856,5 186,7 4503,00 Bulungan 2 61,6 1831,8 185,7 4592,00 Bulungan 3 63,9 1812,7 177,0 4772,00 Average 62,5 1833,67 183,13 4622,33 Kutai 1 6,789 61,4 1853,7 188,0 4367,00 Kutai 2 61,2 1843,2 187,2 4310,00 Kutai 3 61,8 1813,2 182,5 4675,00 Average 61,47 1836,7 185,9 4450,67 Banjar 1 6,315 66,7 1828,4 170,7 3813,00 Banjar 2 66,9 1832,7 170,4 3634,00 Banjar 3 66,3 1831,8 172,1 3366,00 Average 66,63 1830,97 171,07 3604,33

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3.5 Comparison with Previous Researches Table 9 shows a comparison between this study and previous ones, comparing the use of Borneo materials and those from Java. It can be seen that Borneo’s materials have less performance compared to those from Java, both in terms of Marshall characteristics and resilient modulus. Reviewing this test results, it is clear that Borneo’s local materials may not be suitable fir use in stone mastic asphalt since it needs high performance mixture required to sustain heavy traffics. Borneo’s local materials, however, can still be used in asphalt mixture for local roads, where heavy loads do not dominate.

Table 9. Comparison between This Study dan Previous Researches Indicator This Study Previous Researches Banjar Bulungan Kutai Siswosoebroto et al., (2005) Nurani (2010) OAC (%) 6.3 7,2 6,8 5,9 7,0 Stability (kg) 877,9 688,5 730,1 1540 1210,5 Resilient Modulus (MPa) 3604,3 4622,3 4450,7 4751 5682,5

CONCLUSION

The following conclusions can be drawn from this research. Borneo local materials of Banjar, Kutai dan Bulungan meet the requirements for use as aggregate in asphalt mixtures. Out of the three, Banjar material has better performance. From the Marshall characteristics, only mixtures prepared from Banjar material meet the requirements. Compared to other local materials, Borneo materials have lower performance. Borneo materials may still be used in asphalt mixtures provided to be used in local roads where heavy vehicles do not dominate. Borneo materials may not be suitable for use in stone mastic asphalt since it requires high performance materials to sustain heavy loads

REFERENCES

1. Sabuyase. (2009). Database Quarry in Borneo. Final Report. Banjarmasin: Bureau of Public Roads. Department of Public Works. 2. Yamin, A., Aschuri, I., and Djunaedi, E. (2001). The Potential Use of East Kalimantan Local Aggregates as a Road Pavement Materials , Symposium Papers FSTPT to IV. Bali. 3. Wahyudianto, SS, and Tandihari, RT. (2003). Preliminary Study of the Use of Pasir District (East Kalimantan) Aggregate in the Asphalt Mixtures. Unpublished Undergraduate Thesis. Petra Christian University, Surabaya. 4. Gunawan, and Djayadi, D. (2004). A Study to Investigate the Characteristics of Local Materials in Asphalt Mixture. Case Study: Banjar, South Borneo. Unpublished Undergraduate Thesis. Petra Christian University, Surabaya. 5. Siswosoebrotho, BI, Ginting, K., and Soedirdjo, TL. (2005). Workability and Resilient Modulus of Asphalt Concrete Mixtures Containing Flaky Aggregates Shape. Journal of the Eastern Asia Society for Transportation Studies. Vol. 6, pp. 1302 – 1312. 6. Moestofa B. 1996. Laporan Penelitian Penggunaan Bahan Lokal Untuk Konstruksi Tepat Guna Perkerasan Jalan, Departemen Pekerjaan Umum, Balitbang PU, Pusjatan, Bandung. 7. Moestofa B. (1996). Evaluation of Local Materials for Road Construction. Research Report. Bandung: Highway Research Center, Department of Public Works. 8. Wonson K. (1996). Split Mastic Asphalt The European Experience, Paper at the 1996 AAPA Conference Industry pavement, Asphalt Review. 9. Pratiwi, RM. (2009). The Effect of Ash of Sugarcane Waste to the Performance of Split Mastic Asphalt. Unpublished Undergraduate Thesis. Faculty of Engineering, University of Brawijaya, Malang. 10. Noerfadly, Sofyan. (2007). Performance of Split Mastic Asphalt with Cellulose Fibers Additive. Unpublished Undergraduate Thesis. Petra Christian University, Surabaya. 11. Irwanto. (2002). The Effect of Roadcell Additive to the Performance of Split Mastic Asphalt Mixture. Unpublished Undergraduate Thesis. Petra Christian University, Surabaya. 12. Astika, IP. (2003). Effect of Adding Rice Bran to Split Mastic Asphalt characteristics. Unpublished Undergraduate Thesis. Faculty of Engineering, University of Brawijaya, Malang.

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