The Effect of Polypropylene Fiber as an Additive in Open Graded Emulsion Mixture
Paravita Sri Wulandari1*, Albertus Justianto Gunawan1, Bryan Fernando Lembono1, Figo Chrisnando Hendrianto1, Daniel Tjandra1
1 Civil Engineering and Planning, Petra Christian University, Surabaya, Indonesia
*Corresponding Author: [email protected]
Received: 25 April 2023 | Accepted: 20 June 2023 | Published: 30 June 2023
DOI:https://doi.org/10.55057/ijarei.2023.5.2.2
___________________________________________________________________________
Abstract: The impact of global warming in Indonesia is the longer dry season in some areas.
It is important to reduce gas emission that is associated with global warming. In road construction, Cold Asphalt Emulsion Mixture (CAEM) is considered more environmentally friendly than hot mix asphalt because it emits fewer emissions; however, its strength and durability are not as good as those of hot mix asphalt are. In this research, the type of gradation used is open graded. In order to improve the performance of CAEM, 12 mm-long polypropylene fiber was added as an additive. The main purpose of this research is to analyze the effect of adding polypropylene fiber to Open Graded Emulsion Mixture (OGEM) and to determine the curing effects on its parameters. Further analysis of the results showed that polypropylene fiber content at 0.1% could increase the stability of mixture but increasing the content of polypropylene fiber in mixture tended to decrease the stability of OGEM.
Polypropylene fiber performed well to significantly reduce the flow value, but it only performed better at the early age of mixtures.
Keywords: emulsion bitumen, open graded mixture, polypropylene fiber, Marshall test __________________________________________________________________________
1. Introduction
The process of making Cold Asphalt Emulsion Mixture (CAEM), which does not require heating, makes this type of asphalt mixture environmentally friendly and energy-efficient. In addition, CAEM also saves time because it does not require special equipment and has a low risk in the manufacturing process. CAEM can be applied to road construction surface layers with a low-to-medium traffic classification. However, the use of CAEM in Indonesia is generally only intended for repair works. The weaknesses of CAEM include having higher porosity, weak strength at an early age, and requiring a longer curing time than hot mix so that the water mixture can evaporate completely (Thanaya, 2007).
There are two types of gradations that can be used in (CAEM) for the surface layer, namely a mixture of dense gradation and an open gradation mixture. Dense gradation uses coarse aggregate and fine aggregate in balanced proportions. Open gradation uses the same coarse aggregate as well as a small amount of fine aggregate. The use of open gradations in the mixture has a greater porosity, allowing the water surface to flow and be more flexible. However, the use of dense gradation has a higher mixed strength than the open gradation. Based on the type of charge, emulsified asphalt is classified into cationic, anionic, and nonionic. Based on the time of setting, cationic emulsion bitumen is divided into four types, namely slow cationic
setting (CSS), medium cationic setting (CMS), fast cationic setting (CRS), and quick cationic setting (CQS) emulsion bitumen.
Polypropylene is a light synthetic fiber formed from a polypropylene melt. Polypropylene fiber is a type of plastic fiber that is produced using a high level of technology. Polypropylene itself has properties such as heat resistance, high tensile strength, non-toxicity, and chemical resistance.
The addition of polypropylene fiber to asphalt mixtures has been carried out in previous studies on hot-mix asphalt. While there is still a lack of research on the addition of polypropylene fiber to cold mix asphalt. Most of the studies on the effect of adding polypropylene fiber to asphalt concrete showed the results of increasing stability parameters and decreasing flow parameters in asphalt-concrete mixtures (Sholichin and Sutama, 2019; Kim et al., 2018; Koçkal and Köfteci, 2016; Abtahi et al., 2010; Tapkin, 2008). Therefore, this study has a purpose to investigate whether the addition of polypropylene fiber to the Cold Asphalt Emulsion Mixture (CAEM) can have a positive impact on its characteristics and also to evaluate the curing effects on this mixture.
2. Material and Method
Material Specifications
The material used for this research consists of aggregate, water, bitumen emulsion, and polypropylene fiber. The white polypropylene (PP) fibers of 12 mm length were used in this study, as shown in Figure 1. The density of PP fiber is 0.91 gram/cm3. The properties of PP fibers is shown in Table 1. In this study, the middle limit of Open Graded Emulsion Asphalt Mixture (OGEM) specification was selected as design gradation for all specimens. The mixed gradation used is based on the general specifications of Public Works Department of East Java Province, Indonesia (Directorate General of Highways, 2018). Figure 3 shows the gradation of the combined aggregates which was applied for all specimens in this study.
Figure 1: Polypropylene fiber
Bitumen emulsion is a combination of water and bitumen. Cationic bitumen emulsion is a type of bitumen emulsion where the bitumen particles are positively charged. This type of emulsion is commonly used in road construction. Cationic quick-setting (CQS) bitumen emulsions are designed to set and harden quickly upon contact with aggregate. This bitumen emulsion allow for faster curing times. The properties of CQS bitumen emulsion is as shown in Table 2 and Table 3 shows the properties of aggregates. The laboratory tests on bitumen emulsion and aggregates were conducted based on Indonesia National Standard (SNI).
Table 1: Properties of Polypropylene fiber
Material Density
(gram/cm3)
Tensile strength (N/mm2)
Melting point (°C)
Polypropylene fiber 0.91 350 160
Table 2: Properties of CQS bitumen emulsion
Test on bitumen emulsion Method Result Unit Specification
Emulsion bitumen
Viscosity at 25°C SNI 06-6721-2002 43.54 second 20 - 100
Storage stability test, 24 hours SNI 6828:2012 0.88 % -
Particle charge test SNI 03-3644-1994 Positive - Positive
Sieve test SNI 03-3643-1994 0.00 % Max. 0.1
Mixing stability with cement SNI 03-6830-2002 0.61 % -
Residue by distillation SNI 03-3642-1994 60.17 % Min. 60 Residue from distillation test
Penetration, 25°C, 100g, 5s SNI 06-2456-1991 87.83 0.1 mm 40 - 90 Ductility, 25°C, 5cm/min SNI 06-2432-1991 85.50 cm Min. 40 Solubility in trichloroethylene SNI 2438:2015 98.11 % Min. 97.5
Figure 2: Aggregate gradation
Table 3: Properties of aggregates
Test on aggregates Method Result Unit Specification
Coarse Fine
Los Angeles abrasion SNI 2417:2008 19.70 - % Max. 40
Materials finer than sieve No. 200 SNI ASTM C117: 2012 - 3.61 % Max. 8 Bulk density
SNI 1969:2008
2.755 2.51 - -
Apparent density 2.855 2.62 - Min. 2.50
Absorption 1.79 1.73 % Max. 3%
Research Methods
In this study, specimens with 10 cm in diameter were made by adding PP fibers in four differents contents, 0.1%, 0.2%, 0.3%, and 0.4% of the total weight of the mixture. The total mixture contains aggregates according to the design gradation and bitumen emulsion. The total weight of each mixture was designed with weight 1000 gram to give more spaces for sample mixture to expand during the immersion process (Shirini and Imaninasab, 2016).
The initial stage was the preparation of materials for sample mixtures. Bitumen emulsion was poured to the aggregate, which premixed with water as 2% of the total weight. After that, the polypropylene fiber was added gradually to the mixture. Mixture cylinder mold with 10.2 cm in diameter and 7.6 cm in height are used to form cylinder test specimens and compacted with a total of 75 strokes on each side with a Marshall compactor (Wulandari et al., 2019).
Afterward, specimens were left in mold to cure at room temperature for 2x24 hours. Following this step, the specimen were put into the oven for 4 hours at 40 °C, then leave it again at room temperature for 24 hours.
For the capillary immersion condition, the specimen was immersed for 2 x 24 hours alternately on each side, with the water immersion height was at half of the height of specimen (Thanaya, 2007). Immersion of the samples was carried out to obtain the soaked stability, which was to be considered in determining the Optimum Residual Asphalt Content (ORAC) and Optimum Polypropylene Fiber Content (OPFC). Furthermore, Marshall testing was carried out to obtain stability and flow values, and calculations were also carried out to determine volumetric parameters, water absorption, and the density of the mixture. Tests on the effect of a 7-day curing period were carried out after determining the ORAC and OPFC of mixtures. The specimen was cured by leaving it at room temperature for 7x24 hours before immersing it in water for further Marshall testing.
3. Result and Discussion
Determination of the Optimum Residual Asphalt Content (ORAC)
After conducting a series of tests to determine the Optimum Residual Asphalt Content (ORAC), the characteristics of the mixture were obtained for each residual asphalt content studied. The residual asphalt content between 5% to 7% by weight of total mixture were applied with 0.5% intervals, based on the minimum emulsion content in the general specifications of Public Works Department of East Java Province, Indonesia (Directorate General of Highways, 2018). Table 4 shows the properties of the Open Graded Emulsion Asphalt Mixture (OGEM) for each residual asphalt content.
Table 4: Marshall Test results for OGEM control mixtures
Characteristics Residual asphalt content (%) Unit Specification
5 5.5 6 6.5 7
Stability 361.36 413.28 365.62 286.48 271.91 kg Min. 300
Flow 3.13 3.39 4.32 4.06 4.06 mm -
VIM 23.57 23.19 21.82 23.35 24.06 % 20-30
VMA 31.37 31.91 31.59 33.79 35.24 % -
VFB 24.89 27.34 30.96 30.89 31.74 % -
Water Absorption 1.39 1.43 1.5 1.49 1.56 % Max. 4
Density 1.94 1.94 1.95 1.9 1.87 gr/cm3 -
TFA 32.4 36.55 40.75 44.99 49.27 % Min. 20
MQ 115.94 122.37 85.7 71.01 68.88 kg/mm -
The determination of the ORAC value was based on the highest value of stability. This was based on the condition that other characteristics of OGEM had met the specifications specified by the Indonesian Standard. The highest stability value was obtained at an residual asphalt content of 5.5%, at 413.28 kg. Because it showed the best mixing properties, the residual asphalt content of 5.5% was designated as the Optimum Residual Asphalt Content (ORAC).
The Effect of Polypropylene Fiber on Open Graded Emulsion Mixtures (OGEM)
Based on the results of laboratory testing on OGEM with 5.5% of residual asphalt content as shown in Figures 4 to Figure 7, it was found that the main effect of using PP fiber was on reducing the flow value by 25% up to 65% for its variation of 0.1% to 0.4% of PP fiber content.
Moreover, the addition of PP fiber also increased the MQ value so that the asphalt mixture become stiffer. The increase in the MQ value that occured in the open gradation mixture was in the range of 42% to 128% for 0.1% to 0.4% of PP fiber content. Considering the stability values, the addition of PP fiber increased stability of mixture by 6.6% at 0.1% of fiber content but decreased the stability to 23.5% with an increase in content of PP fiber on 0.2% to 0.4%.
The addition of PP fiber had no significant effect on the parameters of VIM, VMA, VFB, density, and water absorption because it showed similar results compared to unmodified OGEM.
Figure 4: Effect of PP fiber on stability values Figure 5: Effect of PP fiber on flow values
Figure 6: Effect of PP fiber on VIM values Figure 7: Effect of PP fiber on MQ values
The addition of 0.1% of PP fiber content on OGEM showed the highest stability value at 441.39 kg. In addition, considering also the MQ value, at 0.4% of PP fiber content showed the highest MQ value of 279.72 kg/mm. This indicates that this mixture is less flexible and cracks can occur more easily when compared to the mixture with 0.1% of PP fiber content, which had an MQ value of 174.06 kg/mm. Considering its nature, open graded is more flexible than dense graded mixture. Thus, 0.1% of PP fiber content was determined as the Optimum Polypropylene
0 50 100 150 200 250 300
0 0.1 0.2 0.3 0.4
MQ (kg)
PP Fiber Content (%)
Fiber Content (OPFC) because this mixture had the most ideal OGEM characteristics. The summary results of the effect of PP fiber on characteristics of OGEM can be seen in Table 5.
Table 5: The effect of PP fiber on characteristics of OGEM Characteristics Polypropylene Fiber Content (%) Unit
Specification
0 0.1 0.2 0.3 0.4
Stability 413.91 441.39 338.99 339.31 316.66 kg Min. 300
Flow 3.39 2.54 1.95 1.86 1.19 mm -
VIM 23.19 22.45 23.62 21.63 22.08 % 20-30
VMA 31.91 31.26 32.29 30.53 30.93 % -
VFB 27.34 28.18 26.89 29.18 28.62 % -
Water Absorption 1.43 1.44 1.50 1.49 1.33 % Max. 4
Density 1.94 1.95 1.92 1.97 1.96 gr/cm3 -
TFA 36.55 36.55 36.55 36.55 36.55 % Min. 20
MQ 122.58 174.06 175.14 183.03 279.72 kg/mm -
The Effect of Curing Period on OGEM with Polypropylene Fiber
Laboratory testing were also carried out to investige the effect of curing period of 7 days on unmodified mixture and mixture with 0.1% of PP fiber content. From Figure 8 to Figure 11, it was found that the addition of PP fiber affected the stability, flow, and MQ parameters.
However, the stability of the PP fiber mixture after a curing period of 7 days did not experience a significant difference compared to the unmodified mixture. Meanwhile, the flow increased by 2.5% and 23.3% for unmodified mixture and PP fiber mixture after curing, respectively.
The increase in flow occurred due to a significant increase in stability after curing. However, PP fiber mixture experienced a decrease in flow of 25% before curing and 10% after curing compared to unmodified mixture. The MQ parameter also increased after a 7-day curing period.
Figure 8: Effect of curing on stability values Figure 9: Effect of curing on flow values
Figure 10: Effect of curing on VIM values Figure 11: Effect of curing on MQ values
In comparison, the PP fiber mixture experienced an increase in MQ of 42% before curing and 9% after curing compared to unmodified mixture. Therefore, it can be concluded that the effect of adding polypropylene fiber could reduce flow and increase MQ, especially at the early age of OGEM. The summary results of the effect of curing time on the characteristics of OGEM for unmodified mixture and PP fiber mixture can be seen in Table 6.
Table 6: The effect of curing time on characteristics of OGEM Characteristics Unmodified mixture PP fiber mixture Unit
Specification No curing 7 days curing No curing 7 days curing
Stability 413.91 663.67 441.39 649.12 kg Min. 300
Flow 3.39 3.47 2.54 3.13 Mm -
VIM 23.19 22.67 22.45 21.69 % 20-30
VMA 31.91 31.45 31.26 30.59 % -
VFB 27.34 27.96 28.18 29.11 % -
Water Absorption 1.43 1.26 1.44 1.59 % Max. 4
Density 1.94 1.95 1.95 1.97 gr/cm3 -
TFA 36.55 36.55 36.55 36.55 % Min. 20
MQ 122.58 191.57 174.06 208.28 kg/mm -
4. Conclusion
Based on a series of laboratory testing that had been carried out in this study, it can be concluded that:
i. For open-graded aggregates and CQS-type bitumen emulsion, the Optimum Residual Asphalt Content (ORAC) was obtained as 5.5%.
ii. For Open Graded Cold Asphalt Emulsion Mixture (OGEM), adding polypropylene fiber could reduce the flow value and increase the Marshall quotient value. However, it should be considered that the addition of polypropylene fiber tended to reduce the stability value of OGEM.
iii. After 7-days curing period, the positive effect of adding polypropylene fiber on flow and MQ value of OGEM was no longer significant when compared to its values at the initial age (without a curing period). For other parameters, there was also no significant changes.
Therefore, it can be concluded that the effect of adding polypropylene fiber to the Open Graded Cold Asphalt Emulsion Mixture (OGEM) was more significant at the initial age.
References
Abtahi, S. M., Ebrahimi, M. G., Kunt, M. M., Hejazi, S. M., & Esfandiarpour, S. (2011).
Production of Polypropylene-Reinforced Asphalt Concrete Mixtures Based on Dry Procedure and Superpave Gyratory Compactor. Iranian Polymer Journal (English Edition), 20(10), 813-823.
Directorate General of Highways (2018). General Specifications. Public Works Department of East Java Province (in Bahasa Indonesia).
Kim, M. J., Kim, S., Yoo, D. Y., & Shin, H. O. (2018). Enhancing Mechanical Properties of Asphalt Concrete Using Synthetic Fibers. Construction and Building Materials, 178, 233-243. https://doi.org/10.1016/j.conbuildmat.2018.05.070.
Koçkal, N. U., & Köfteci, S. (2016). Aggressive Environmental Effect on Polypropylene Fibre Reinforced Hot Mix Asphalt. Procedia Engineering, 161, 963-969.
https://doi.org/10.1016/j.proeng.2016.08.834.
Thanaya, I. N. A. (2007). Review and Recommendation of Cold Asphalt Emulsion Mixtures (CAEMs) Design. Civil Engineering Dimension, 9(1), 49-56.
https://doi.org/10.9744/ced.9.1.pp.%2049-56
Shirini, B., & Imaninasab, R. (2016). Performance Evaluation of Rubberized and SBS Modified Porous Asphalt Mixtures. Construction and Building Materials, 107, 165- 171. https://doi.org/10.1016/j.conbuildmat.2016.01.006.
Sholichin, I., & Sutama, D. A. (2019). Variations in The Addition of Polypropylene Fiber, Fly Ash and Immersion in Asphalt Mixtures on Stability and Flow. International Journal of Civil Engineering and Technology, 10(2), 2032-2039.
Tapkin, S. (2008). The Effect of Polypropylene Fibers on Asphalt Performance. Building and Environment, 43(6), 1065-1071.
Wulandari, P. S., Kertorahardjo, K., Thesman, A., & Tjandra, D. (2019). Effect of Crumb Rubber as Fine Aggregate Replacement in Cold Mixture Asphalt. Civil Engineering Dimension, 21(2). https://doi.org/10.9744/ ced.21.2.107-112.
