International Conference of Applied Science on Engineering, Business, Linguistics ISSN : 2598-2532 and Information Technology (ICo-ASCNITech)
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360
Characteristic of Warm Mix Asbuton Modified Asphalt
with Natural Wax Based Additive
Tedi Santo Sofyan
1, a)R Anwar Yamin
2, b)Imam Aschuri
3, c)R.A Sri Martini
4, d)1,2)Pusjatan, Jl. AH. Nasution No. 264 Bandung 40294 3)Itenas, Jl. PH. H. Mustofa No. 23 Bandung 40124
4)Universitas Muhammadiyah, Jl. Jend. A. Yani, 13 Ulu Palembang 30252
a)[email protected] b)[email protected] c)[email protected] d)[email protected]
Abstract - Environmentally friendly technologies and energy saving have been developed in various types of industries to respond environmental issues, especially global warming. In the pavement construction industry, the use of Hot Mix Asphalt (HMA) is one important issue that contributes increasing of global warming, especially HMA that uses modified asphalt such as asbuton modified asphalt where its mixing and compacting temperature were higher than conventional HMA. Warm Mix Asphalt (WMA) is one of the technologies of pavement that was developed to address the issue of global warming. Many attempts have been made globally to produce WMA with performance equivalent to HMA but produced at a lower temperature of 20oC - 40oC. Various additives technology has created, produced and has been used for WMA globally. From a variety of wax-based additives available in the market, none of which use the natural wax as a main ingredient. One type of natural wax is beeswax. This study aims to know potential use of beeswax as an additive in producing of WMA mixture with asbuton modified asphalt as a binder. This study hypothesized that beeswax is a natural additive that can be used to produce WMA mixture. A series of laboratory tests on the properties of asphalt and asphalt mixture is made to achieve that goal. In this study, 5 variations composition of beeswax and other materials used (combined-beewax-additive) as an additive for asbuton modified asphalt. However, in all variations using 66% of beeswax. From this study it was known that beeswax is a potential natural wax that can be used as the main ingredient additives for asbuton modified asphalt. Addition of combined-beewax-additives is not change the properties of asphalt significantly but in the mixture properties it tend to decrease the Marshall stability, Marshall quotient, ITSR and modulus. However, the additional of 0.5% combined-beeswax-additive into asbuton modified asphalt can meet the requirement on General Specification of Bina Marga 2010 3rd Revision with reducing of mixing and compaction temperatures of 30oC and mixture performance equivalent to HMA which used asbuton modified asphalt as a binder and more over has a better fatigue and aging resistance.
1. INTRODUCTION
Environmentally friendly and energy saving technologies have been developed in various type of industries to respond environmental issues especially global warming. In the pavement construction industry, the use Hot Mix Asphalt (HMA) contributes to increase of global warming effect, especially HMA that use modified binder such as asbuton preblend binder which is need higher mixing and compacting temperature. Warm Mix Asphalt (WMA) is one of the pavement technology that developed to address the global warming issues.
With WMA technology it is possible to produce asphalt mixtures at significantly lower temperatures than HMA by adding certain external agents. This technology helps to reduce the emissions of greenhouse gases by 20-30%. It also has significant effect on asphalt mixture characteristic for example stability, density ITS, TSR, resilient modulus, fatigue behaviour, etc [5].
Some studies have shown that WMA can be produced at temperatures of 20-400C lower than HMA
with equivalent performance. The lower production temperature also reduces the ageing of the bitumen during the production stage, which result in an improved thermal and fatigue cracking resistance [2].
Various additive technologies for WMA have been created, manufactured and available in the market. In general, additive technology for WMA is (1) foaming techniques (which are devided into water-based and water containing), (2) organic or wax additives, (3) chemical additives [8]. The various additives that have been available in the market, especially for wax-based additives, no one has used natural wax as the main ingredient. The advantage of using natural wax is because this material is not derived from petroleum so it can be renewable and more environmentally friendly. One type of natural wax is beeswax which is derived from bee hives. Beeswax has a good potential to be used as a main ingredient additive for WMA.
361 many developed various technology processes to produce a warm asphalt mixture in europe and america. Additive product for warm mix asphalt have been widely marketed with different technology processes and trademark [1].
Various studies on the additives of warm asphalt mixtures have been widely practiced. The results of the study were varied in each study. The difference result in each study was caused by various factors such as the type and amount of additives used, the humidity of the material used, the mixed design method used, the material used, the environmental conditions, and others [8].
A study examines the feasibility of some WMA additives, that is Sasobit, Evotherm and Advera which are commonly used. The results of the study showed that two of these additives (Evotherm and Advera) did not significantly affect the asphalt properties. The Asphalt PG value and dynamic modulus of the WMA are still the same as the original asphalt (HMA). WMA with Sasobit increase the rut resistance significantly. WMA mixture showed greater susceptibility to moisture conditioning than HMA mixture [9].
A study on paraffin-based additives has also been done. Leadcap additive and asphalt buton preblend BNA are used in this study. The results of this study indicate that the WMA mixture with 1% Leadcap can meet the requirements of the specification to decrease the production temperature of 150C. In addition, this WMA mixture also has more rut resistance, moisture susceptibility, and ravelling resistance better than HMA mixture [6].
WMA additives developed in this research are natural wax based additives which are the product of honeycomb or better known as beeswax. Beeswax is a pure candle formed from the Apis Mellifera honeycomb. Every 8 pounds of honey will produce 1 pound of beeswax. Beeswax consists of 70% esters and 30% acids and hydrocarbons [4]. Beeswax has a low melting point between 62-64 °C and its specific gravity at 150C is 958-970 kg / m3 [7].
3. HYPOTHESIS
Beeswax can be used as a WMA additive to lower the asphalt mixture production temperature with equivalent or better quality compared to HMA.
4. RESEARCH METHODOLOGY
The methodology used in this research is experimental through laboratory experiments. Stages of this research activity are:
- Looking for a beeswax based additive formula and its optimum content mixed with asphalt which is meets the specification.
- Testing the material used in the research
- Experiments on asphalt mixtures with additive content and temperature drop variation and use HMA as comparison
- Evaluating the experiment results and compare the characteristic of HMA and WMA mixture
5. LABORATORY TEST RESULT
5.1 Formula and Optimum Content of Beeswax Additive
International Conference of Applied Science on Engineering, Business, Linguistics ISSN : 2598-2532 and Information Technology (ICo-ASCNITech)
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Table 1. Buton Modified Asphalt (BNA Blend) + Beeswax Additive Test Result
No. Type of testing Test Method
Test Result
Spec*) Units BNA BNA + 1%
Additive 1
BNA +1% Additive 2
BNA + 1% Additive 3
BNA + 1% Additive 4
BNA + 1% Additive 5
BNA + 0,5% Additive 4
1 Penetration at 25 oC SNI 2456 : 2011 56 62 60 60 62 65 62 Min 50 dmm
2 Softening Point SNI 2434 : 2011 53.4 52.25 53.25 53.55 54.05 53.45 53.45 ≥ 50 oC
3 Ductility at 25
oC, 5 cm/
minute SNI 2432 : 2011 >140 54 49 92 >140 >140 >140 ≥ 100 Cm
4 Solubility (C2HCl3) SNI 06-2438-1991 95,352 94 95 - 99.821 99.827 99.936 ≥ 90 %
5 Specific Gratvity SNI 2441 : 2011 1,0208 1.0413 1.0437 - 1.0211 1.0206 1.0248 ≥1,0 -
6 Flash Point ( COC ) SNI 2433 : 2011 270 280 280 - 278 274 282 ≥232 oC
7 Loss on Heating (TFOT) SNI 06-2440-1991 0,289 0.495 0.405 - 0.509 0.477 0.541 ≤0,8 %
8 Penetration after TFOT SNI 2456 : 2011 39,3 41 40 - 44 45 45
(≥54% thd original)
dmm
9 Softening Point after TFOT SNI 2434 : 2011 56,2 58.45 59.1 - 55.9 55.5 56.05 - oC
10 Ductility after TFOT SNI 2432 : 2011 94 19 18 - 50 46 50 ≥ 50 Cm
11
Difference in softening point (sytorage stability) 1,3 0,9 - 1,6 1,9 1,6 ≤ 2.2
oC
- Top Softening point 51.8 52.6 - 54.5 53.8 54.8 -
- Bottom softening point 53.1 53.5 - 56.1 55.7 56.4 -
12 Mixing Temperature AASHTO-72-1997 154 - 159 151 – 158 152 – 159 - 150-156 150-156 149-155 - oC 13 Compacting Temperature AASHTO-72-1997 142 - 148 137 – 144 139 – 145 - 138-144 138-143 137-142 - oC
363 Table 1 shows that from 5 type of additives which have been tested only additive 4 and additive 5 that meet asphalt modification requirements in Bina Marga General Specification of 2010 Revision 3.
The difference between additive 4 and additive 5 test result is not very significant, but when it seen from the softening point and storage stability parameter, the additive 4 is better. So for the asphalt advanced test the additive 4 is used to seek its optimum content.
The advanced asphalt test is carried out by DSR to determine the rheology, critical temperature and performance grade of the asphalt. The asphalt sample
Table 2 shows the comparison of critical temperature values of the three types of asphalt either through DSROriginal, DSRRTFOT or DSRPAV testing. It is also shows that all asphalt tested classified in the category of 64-XX PG performance.
From the Table 2 it is also seen that the use of 0.5% additive provide the most optimum improvement. This is indicated from the critical temperature value where the use of 0.5% additive has highest value. The critical
temperatur value is is 69.17°C for DSROriginal, 75.66°C for DSRRTFOT and 21.47°C for DSRPAV.
The higher critical temperature value of DSROriginal and DSRRTFOT indicate that asphalt has more resistance to rutting and higher asphalt modulus, while the higher critical temperature value of DSRPAV indicate that the asphalt more resistance to fatigue, so it can be concluded that the use of 0.5% additives provides the highest stiffness modulus and resistance to rutting and fatigue.
To know the effect of additive to level of asphalt aging is seen from Aging Factor, that is ratio between parameter of G*/sinδ after aging process (RTFOT) and original.
Assuming that all three asphalt classified in the class of 64-XX PG performance, then the ratio of G*/sinδ done by repeated heating. Addition of 0.5% additive can decrease the aging factor from 5.5 to 4.7 or decrease by 14.5%, while the addition of 1% additive can increase aging factor from 5.5 to 5.87 or an increase of 6.73%.
5.2 Aggregate Physical Properties and Gradation
The aggregate used in this experiment taken from PT Yasa Subang. The characteristics and grading of the aggregate used have met the requirements of the General Specification of Road and Bridges 3rd Revision for AC-WC [3].
5.3 Mix Design
Since the additive used is a novel material, in order to find the mixing and compacting temperatures which can be accommodated by this additive is carried out by varying the mixing and compacting temperatures and varying the beeswax additive levels.
In this WMA Marshall experiment, the mixing and compacting temperature is decreased by 100C, 200C and 300C from its HMA temperature, and its applied for each additive content of 0%, 0.5%, 1.0% and 1.5%. Results of mixture experiment with additive and temperature variations are presented in Table 3.
Asphalt Sample Type Temperature
BNA Blend+ 1 % Add -0.0394 26.41
DSR PAV; (|G*|.Sin(δ) = 5000 kPa)
BNA Blend+ 0% Add -0.0436 23.88
BNA Blend+ 0,5% Add -0.0387 21.47
BNA Blend+ 0,5% Add -0.0507 75.66
BNA Blend+ 1 % Add -0.0501 73.61
BNA Blend+ 1 % Add -0.0483 65.44
DSR RTFOT ;(|G*|/Sin(δ) = 2.2 kPa)
BNA Blend+ 0% Add -0.0517 75.30
DSR ORI ;(|G*|/Sin(δ) = 1 kPa)
BNA Blend+ 0% Add -0.0503 67.97
International Conference of Applied Science on Engineering, Business, Linguistics ISSN : 2598-2532 and Information Technology (ICo-ASCNITech)
Politeknik Negeri Padang and Politeknik Ibrahim Sultan, 13-15 October 2017
364 Table 3. The Result of Mixed Asphalt Properties of Marshall Experiments
Mixture Properties
Mixing and Compacting Temperature and Additive Content
Spec* Units
0% aditif 0.5% aditif 1.0% aditif 1.5% aditif
HMA (164/150)
WMA (154/140)
WMA (144/130)
WMA (134/120)
WMA (154/140)
WMA (144/130)
WMA (134/120)
WMA (154/140)
WMA (144/130)
WMA (134/120) Optimum
Asphalt
Content 5.75 5.9 6.2 5.9 5.9 5.8 6.1 5.8 6.2 6.1 - % total mix
Density 2.375 2.357 2.385 2.367 2.372 2.347 2.369 2.355 2.330 2.346 - gr/cm3
VIM 3.48 4.37 3.38 3.99 3.50 4.76 4.13 4.67 4.46 4.29 3 - 5 %
VMA 15.76 16.52 15.79 16.09 16.00 16.78 16.33 16.49 17.66 17.08 Min 15 %
VFB 77.94 73.62 78.50 75.26 78.13 71.74 74.86 71.78 74.72 74.99 Min 65 %
Stability 1370 1254 1245 1166 1073 1095 1096 952 1032 1162 Min 1000 Kg
Flow 3.29 3.45 3.80 3.38 3.91 4.01 4.31 3.42 3.85 3.62 2 - 4 mm
MQ 416.9 363.9 327.7 345.0 274.4 273.2 254.1 278.5 268.0 321.2 Min 300 Kg/mm
Retained
Stability 95.30 94.18 96.15 94.80 95.20 92.23 90.24 84.99 91.45 94.53 Min 90 %
365
5.4 Ruttingg Resistance of Asphalt Mixtures
The rutting resistance of the mixture was tested using Wheel Tracking Machine (WTM) with 6.4 kg/cm2 load according to Japan Road Association 1980 method.
The specimens for this test were carried out at mixing and compacting temperature of 30°C below HMA with 5.9% asphalt content according to Marshall experimental results. The test temperature was carried out at 60°C with 42 passes per minute. The results of the test are presented in Table 4.
Table 4 Rutting Resistance Test Result
Period (minute) Passing
Types of Asphalt Mixture Sample
Units 0.0%
(1640C/1500C)
0.5% (1340C/1200C)
1.0% (1340C/1200C)
0 0 0.00 0.00 0.00 mm
1 21 0.95 0.99 0.90 mm
5 105 1.37 1.42 1.37 mm
10 210 1.61 1.63 1.61 mm
15 315 1.76 1.77 1.79 mm
30 630 2.05 2.04 2.13 mm
45 945 2.23 2.22 2.37 mm
60 1260 2.37 2.38 2.55 mm
DO = Initial Deformation 1.81 1.74 1.83 mm
RD = Rate of Deformation 0.0093 0.0107 0.0120 mm/menit DS = Dynamic Stability 4500.0 3937.5 3500.0 passes/mm
5.5 Modulus Resilient of Asphalt Mixture
The tests were carried out on temperature of 25°C, 35°C and 45°C. The modulus resilient test was performed on HMA samples and WMA sample with 0.5% and 1.0% additive content. Mixing and compacting temperatures for HMA is 1640C and 1500C, while for WMA is 1340C and 1200C. Resilient Modulus test results are presented in Figure 2.
Figure 2. Modulus Resilient at Temperature of 250C, 350C and 450C
5.6 Fatigue Resistance of Asphalt Mixture
The fatigue resistance test was carried out using a fatigue test device according to AASHTO T 321 method at test temperature of 200C.
The test specimens were compacted using a WTM compactor with specimens thickness adapted to the specimen for testing of the fatique.
Fatique testing is carried out for 2 types of mixture, which is HMA mixture and WMA mixture. The test specimen in the form of a beam is given a repetitive load with a fixed strain until the beam has failured. The failured occurs when the modulus value has reached 50% of the initial modulus. The results of the fatique test are shown in Figure 4.
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5.7 Indirect Tensile Strength (ITS) Test Result
The indirect tensile strength test of the asphalt mixture is intended to know the strength of the asphalt mixture due to the influence of water. Testing and conditioning of the specimen refers to the AASHTO T 283 method except for conditioning at -180C for 3 hours is not performed. The test was carried out for HMA mixture and WMA mixture. The result of indirect tensile strength test is presented in Figure 4.
Figure 5. ITS and ITSR graph for HMA and WMA Mixture
5.8 Abrassion loss of Asphalt Mixture with Cantabro
Cantabro test is typicaly used for open graded mixture, in this study cantabro test performed only to compare the ravelling resistance between HMA and WMA mixture. Ravelling is expressed with percent of loosed material after the specimen has 300 rotation inside the Los Angeles Abrassion Test tool. To observe in detail of the loosed material that occured, the specimen weight are measured every 50 rotations until reach 500 rotations. The results of the test are shown in Figure 6.
Figure 6. Cantabro Test Result
Based on the test results it is known that the cantabro loss for HMA is 2.9% and for the WMA is 1.8%. So it can be concluded that the WMA with natural wax additive is more resistant to ravelling compared to the hot mixture.
6. DISCUSSION
6.1 Formula and additive content
Based on the asphalt and mixture test data, it can be concluded that the formula and natural wax additive content that meet the specification of the General Specification of Bina Marga 2010 3rd revision is additive formula 4. Addition of 0.5% natural wax additives to asbuton preblend asphalt did not significantly change the asphalt properties. The mixing of additives and bitumen can be done directly in Asphalt Mixing Plant (AMP) because the additive can dissolve at temperature 62-64°C.
The decrease of mixing and compacting temperature based on result of asphalt test is very small that is between 40C - 50C. However, the value of mixing and compaction temperature based on this viscosity can not be used as a reference. To determine the temperature drop that can be achieved is refer to the mixture density value. The value of the temperature drop is obtained from the temperature which can produce the WMA mixture with the same density as the HMA mixture [6].
Based on the results of DSR test showed that the addition of 0.5% additives gives a pretty good effect to asphalt properties. Addition of 0.5% additives provides the most optimum improvement seen from the highest critical temperature for DSROriginal and DSRRTFOT and the lowest critical temperature values in DSRPAV testing. The higher critical temperatures of DSROriginal and DSRRTFOT signifies higher resistance to rutting and higher asphalt modulus, while the lower of DSRPAV critical temperature signifies higher resistance to fatigue. So it can be concluded that the use of 0.5% additive has the highest stiffness modulus and more resistance to rutting and fatigue.
367 the aging rate increased by 6.73% against the original asphalt. Original Asbuton preblend asphalt has a very high aging rate when compared with conventional asphalt. The cause of high aging levels is probably due to the process of producing the Asbuton preblend asphalt is done by repeated heating.
6.2 WMA Mixture Performance
The performance of the WMA mixture if viewed from the marshall test results, only 0.5% additive indicating that this mixture complies the General Specification of Bina Marga 2010 3rd Revision even though the production temperature is lowered by 300C. The properties of WMA mixture with 1% and 1.5% additive content did not meet the specification in terms of flow and Marshall Quotient (MQ) value. The MQ value shows the ratio of load to deformation and can be used as an indication of the stiffness of the mixture. Low MQ values will cause the mixture to be susceptible to deformation as it becomes softer.
The performance of a WMA mixture in terms of rutting resistance shows that all WMA mixture still meet the requirements of the General Specification 2010 3rd Revision that is above 2500 passes/mm. From the test results also seen that with the increasing use of natural wax additives will reduce the mixture dynamic stability. This results is in line with Marshall test results where the stability and MQ value decrease as the additive content increase.
The dynamic stability value of HMA mixture (as control) is greater than the WMA mixture with 0.5% and 1.0% additives. Dynamic stability values of WMA with 0.5% additives is greater than 1.0% additives thus a WMA mixture with 0.5% additive still have better resistance to deformation than WMA mixture with a 1.0% additive.
Based on the resilient modulus test it can be seen that the addition of the natural wax additive will decrease the resilient modulus value. The higher of the additive content, the lower resilient modulus value. This is in line with the result of Marshall test, where the higher additive content will lower the stability value. The effect of test temperature on the greatest decrease in modulus values occurs between 25°C and 35°C and its occurs to all mixtures. This is indicated by a steeper slope of resilient modulus line compared to the 35°C and 45°C slope.
HMA fatigue line compared with WMA fatique line, at the same strain, shows that HMA mixture has shorter resistance to load repetitions than HMA mixture. This can mean that WMA mixture with 0.5% additives having fatigue resistance better than HMA mixture. Buton asphalt preblended does not significantly change the asphalt properties but can decrease mixing and compaction temperatures as much as 300C with quality equivalent to the HMA mixture. b. Buton asphalt preblended with 0,5% natural wax
additive has more resistance to fatigue cracking when compared to the original buton asphalt preblended and it can also decrease the rate of asphalt aging.
c. The advantages of using this additives are having a quality equivalent to HMA with fuel saving in AMP. Other direct advantage is the WMA produced is more resistant to fatigue cracking and ravelling compared to HMA mixture.
d. As the enhancement of natural wax additive content to buton asphalt preblended can decrease modulus, stability, marshall quotient and ITSR value. Therefore, the additive content for the buton asphalt preblended is limited to 0.5%. The optimum additive content should be analysed for new material used.
7.2. Recomendations
Recomendation that can be submitted based on the results of this study is further studies with field trials to obtain how the application techniques and its performance in the field.
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International Conference of Applied Science on Engineering, Business, Linguistics ISSN : 2598-2532 and Information Technology (ICo-ASCNITech)
Politeknik Negeri Padang and Politeknik Ibrahim Sultan, 13-15 October 2017
368 7. Wikipedia, Beeswax, Retrieved from
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