ANALYSIS OF LOCAL SANDED SOIL WITH COCONUT COIR FIBER REINFORCEMENT AS SUBGRADE ON STRUCTURAL PAVEMENT

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 10, October 2017, pp , Article ID: IJCIET_08_10_083 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed ANALYSIS OF LOCAL SANDED SOIL WITH COCONUT COIR FIBER REINFORCEMENT AS SUBGRADE ON STRUCTURAL PAVEMENT Novita Pradani Civil Engineering Department, Faculty of Engineering, Tadulako University, Palu, Indonesia Irdhiani Civil Engineering Department, Faculty of Engineering, Tadulako University, Palu, Indonesia Joko Wibowo Civil Engineering Department, Faculty of Engineering, Tadulako University, Palu, Indonesia ABSTRACT Soil is the important material in a construction work as the basis for foundation, so it takes a soil that must have a high bearing capacity soil with a small decrease. This study was conducted to determine the effect of coconut (coir) fiber to the density of the soil, the California Bearing Ratio (CBR) value and the bearing capacity generated in locally sandy soil. Tests conducted on the soil involved testing the physical properties (sieve analysis test and specific gravity test) and mechanical properties (compaction test, unsoaked and soaked CBR test). The testing of coconut coir fibre are density test and tensile strength test. The length variation of coir fibre used are cm and cm with the addition of coir fiber percentage of 0%, 0.5%, 1% and 1.5%. The result showed that the addition of coir fiber can be increase CBR value and bearing capacity of sanded soil. At unsoaked condition, the highest CBR value was about 51,87% and bearing capacity was 9,14 which are reached at 1,5% percentage of coir fiber and 1,5-2 cm of coir fiber long. While in soaked condition, the highest CBR value was about 38,88% and bearing capacity was 8,59 which are reached at 0,5-1% percentage of coir fiber and 1,5-2 cm of coir fiber long. It is concluded that proportion of 0.78% coir fiber and 1,5-2 cm of length in a soil is optimum percentage of materials having maximum soaked CBR value. Hence, this proportion may be economically used in road pavement and embankments. Key words: CBR value, Bearing Capacity, Coir Fiber, Road Subgrade and Sandy Soil editor@iaeme.com

2 Novita Pradani, Irdhiani and Joko Wibowo Cite this Article: Novita Pradani, Irdhiani and Joko Wibowo, Analysis of Local Sanded Soil with Coconut Coir Fiber Reinforcement as Subgrade On Structural Pavement, International Journal of Civil Engineering and Technology, 8(10), 2017, pp INTRODUCTION The road pavement is placed on the ground floor, thus the overall quality and durability of a pavement construction can not be separated from the properties possessed by a foundation. Compaction is a basic method of soil stabilization, where the amount of poor compaction will result in decreased soil stability in road works. Compacted base soils to optimum densities have good carrying capacity and have the ability to sustain volume changes during the service life. Soil properties are influenced by soil type, texture, density, water content, environmental conditions, and so forth. Land carrying capacity for roads can be estimated using CBR checks. To improve the carrying capacity of the soil, various efforts have been made to improve the technical nature of the soil such as with the stabilization or addition of materials to increase soil strength. One such form of business is by the addition of fiber both synthetic fibers and natural fibers. In ancient times, fiber was used for reinforcing soils. Early civilizations added straws and plant roots to soil bricks and cob wall to improve their properties although their mechanisms were not fully understood. However, modern geotechnical engineering has focused on the use of planar reinforcement. The reinforcing of soil with discrete fibers is still a relatively new technique in geotechnical projects [1]. One of the natural fibers that are often used as a material for soil reinforcement is coconut coir fiber. According Mwasha (2009) that coir fiber has good strength, characteristic and resistance to biodegradation for a long period of time. Fiber coir has high buoyancy, is resistant to bacteria, salt water, while its weaknesses can not be twisted properly and belong to a rigid fiber [2]. Coconut Fiber itself is considered cheap and easy to get it especially in the area of Central Sulawesi, Indonesia. This is biodegradable and hence do not create disposal problem in environment [3]. Coconut fiber or Coir is a natural fiber extracted from the husk of coconuts and used in products such as floor mats, doormats, brushes, and mattresses. Coir is the fibrous material found between the hard, internal shell and the outer coat of a coconut. The fibers are normally mm long and consist mainly of lignin, tannin, cellulose, pectin and other water soluble substances [4]. Previous studies related to soil reinforcement, especially with coco fiber has been widely practiced. The mechanical properties of fiber (synthetic and natural) reinforced soil have been investigated by various researchers. All previous studies have shown that addition of fiber reinforcement causes significant improvement in strength of the soil and increases its stiffness [5]. The present study is set out to figure out performance of locally sandy soil as road subgrade with coconut coir fiber reinforcement. 2. MATERIALS AND METHODOLOGY 2.1. Materials Soil samples were collected from Wisata Road +500 m from junction of Soekarno-Hatta Rd. dan Pariwisata Rd. in Palu, Indonesia as shown in Figure 1.Soil sample was used is disturbed soil which taken from +0,3-1,0 m of depth. The soil samples were air dried and stock-piled for laboratory work editor@iaeme.com

3 Analysis of Local Sanded Soil with Coconut Coir Fiber Reinforcement as Subgrade On Structural Pavement Coconut Fiber Material used is derived from coco fiber obtained by taking the residual yield (waste) of coconut use in Wani Village Tanantovea District, Donggala Regency, Central Sulawesi. Percentage of coconut coir fiber are 0%, 0,5%, 1% and 1,5% by weight of soil mixture. The fibers were extracted manually and separated into strands of about 2 group are 1,5-2 cm long and 2,5-3 cm long (Figure 2 and 3). Source: Google Earth, 2016 Figure 1 Map Showing the Soil Sample Location Figure 2 Preparation the coir fiber Figure 3 Coconut coir fiber editor@iaeme.com

4 Novita Pradani, Irdhiani and Joko Wibowo 2.2. Methodology The sieve analysis was performed to determine the distribution of the coarser, larger-sized particles in the soil, while the hydrometer method was used to determine the distribution of the fine particles in the soil samples. The test was carried out in accordance with standard [6]. Further laboratory test was carried out to determine the plastic and liquid limits of the soil samples. The tests were carried out in accordance with standard [7]. Compaction test was carried out to determine the optimum moisture content at which the maximum dry unit weight was attained for soil samples using standard Proctor apparatus (Figure 4). Figure 4 Compaction Process In addition, the California bearing ratio test (Figure 5) were carried out on the soil samples with sample specimens for the tests prepared based on the outcome of the compaction test results. The value of soil bearing capacity was obtained by using the correlation equation to the value of CBR or the graph (Figure 6). That graph and equation based on standart [8] Bearing Capacity (DDT) = 1, ,3592 log (CBR) Figure 5 CBR Testing editor@iaeme.com

5 Analysis of Local Sanded Soil with Coconut Coir Fiber Reinforcement as Subgrade On Structural Pavement Figure 6 Correlation between Bearing Capacity and CBR value Source: SKBI /SNI NO: F Varying percentages of coconut fiber (0%, 0.5%, 1.0% and 1.5%) by weight were mixed with soil sample and two varying length of coconut fiber (1,5-2 cm and 2,5-3 cm). Altogether aside control samples, twenty four samples of various percentages of coir coconut fiber were prepared. The samples geotechnical properties such as optimum moisture content, maximum dry density, CBR and bearing capacity parameters were determined following the procedures used to measure the control samples geotechnical properties determination. All experiments carried out were done with three replicates. 3. RESULT AND DISCUSSION 3.1. Soil According to the USCS (Unified Soils Classification System), the requirement of good graded sand type (SW) is Cu value> 6 and Cc value between 1-3 and percent (%) pass filter no.200 <5%. From the value obtained was uniformity coefficient (Cu) meet, while for the value of gradation coefficient (Cc) does not meet those requirements. So the soil can be classified as a bad graded sand soil. So the sandy soil which is reviewed in this research is bad graded soil (SP). Meanwhile, based on the American Association of State Highways and Transportation Officials (AASHTO), the classification of tested soil material was determined based on grain size criteria. From the results of the screening test, the percentage of samples of soil passing through filter No.200 was 2.43% indicating coarse-grained soil, for filter No.40 percentage of passing 30.21% indicating that the soil samples were categorized as A-1-a and A -1-b, then the result of the filter No.10 with the percentage of escapes that is 50.70% so that the soil is categorized as A-1-b Coconut Coir Fiber Based on the results of the specific gravity test, coconut fiber is obtained by And tensile strength test result of coco fiber obtained by tensile strength of coco fiber (diameter ± 3 mm) is 39,63 Mpa editor@iaeme.com

6 Novita Pradani, Irdhiani and Joko Wibowo 3.3. CBR value of Sandy Soil and Coconut Coir Fiber Mixture The addition of coco fiber to sandy soil in CBR testing, changed the soil CBR to be higher when compared with the CBR value of soil without coco fiber. The increase of CBR value is influenced by the percentage and variation of fiber length from coconut fiber. Tests were performed on previously compacted samples under optimum moisture conditions. The sample test was carried out under non-submerged conditions and submerged conditions for 4 days. CBR test results can be seen in the following table. Fiber length variations 1,5-2,0 cm 2,5-3,0 cm Table 1 Test Results of CBR Laboratory Variation of Average CBR value (%) fiber percentage (%) Unsoaked Soaked 0 38,96 30,89 0,5 46,16 37,57 1,0 50,83 38,50 1,5 51,87 31, ,96 30,89 0,5 42,19 35,50 1,0 43,57 36,42 1,5 44,61 31,35 Table 1 shows that the average CBR value of cm variation in fiber length tends to increase with increasing percentage of coco fiber in sandy soil, the highest increase in 1.5% coco fiber with unsoaked conditions. For soaked conditions CBR values also increased in the addition of fiber 0% to 1%, after which the value of CBR decreased. The optimum CBR value occurs between 0.5% and 1% addition of fiber with CBR value of 38.88%. While the variation in fiber length of cm also increased. CBR values in unsoaked conditions increased from 0% to 1.5%, but the value of soaking CBR only increased from 0% to 1%. The optimum CBR value occurred between 0.5% and 1% addition of fiber with CBR of 36.61%. Addition of fiber 1.5% variation of fiber length 1,5-2 cm and 2,5-3 cm at soaking CBR decreased, this happened because of water fill the pore of soil and coconut fiber, so surface of fiber more slippery And the reduced carrying capacity of the soil. Figure 7 CBR Values of Sandy Soil at Different Coir Fiber Percentage and Length editor@iaeme.com

7 Analysis of Local Sanded Soil with Coconut Coir Fiber Reinforcement as Subgrade On Structural Pavement Figure 7 shows the comparison of CBR values generated on the addition of variation of coco fiber with fiber length of cm and cm, the highest CBR value occurs in the addition of cm fiber. Differences in CBR values that occur due to fiber length, the longer the fiber used, the lower the CBR value. Coconut fiber coat has a slippery surface, the longer the fiber then the inter-fiber meeting with other fibers will occur, so friction that occurs fiber with other fibers causes friction between the fiber and the soil is reduced. The shorter the fiber will be the greater the tensile strength of the fiber. When a soil becomes denser, the bond between the grains is stronger, so that the resistance will be greater. With the addition of coco fiber soil conditions are getting better. Coconut fiber fibers mixed in the soil will randomly form mesh elements that can increase the CBR value Bearing Capacity of Sandy Soil and Coconut Coir Fiber Mixture From the results of CBR testing can be obtained the value of soil bearing capacity (DDT). The correlation between CBR value and soil bearing capacity can be determined using graphs or by using the soil bearing power formula. Unsoaked CBR value for variation of fiber length of cm coconut fiber is 51,87% at percentage of coconut fiber addition 1.5%, while at soaked, CBR value optimum is 38,88% at percentage variation of coir fiber Coconut between 0.5% and 1%. Fiber length variations 1,5-2,0 cm 2,5-3,0 cm Table 2 Bearing Capacity of Soil Sample Variation of fiber Bearing Capacity percentage (%) Unsoaked Soaked According to the result (Table 2), the variation of 1.5% coco fiber in unsoaked conditions resulted in the largest CBR value of 51.87% for variations in fiber lengths of cm and % for variations in fiber length of cm, the value was put into Bearing capacity (DDT) formula, the value of soil bearing capacity (DDT) is 9,14 for variation of fiber length 1,5-2 cm and 8,86 value of soil bearing capacity (DDT) obtained for Variation of fiber length of cm. In the variation between 0.5% and 1% coco fiber in soaked condition with optimum CBR value of 38.88% for variation of fiber length of cm and 36.61% for variation of fiber length of cm, The value is inserted into the soil bearing capacity power formula (DDT), resulting in the value of soil bearing capacity (DDT) of 8.58 for variations in fiber length of cm and 8.47 value of soil bearing capacity (DDT) obtained for variation in fiber length from 2.5 to 3 cm editor@iaeme.com

8 Novita Pradani, Irdhiani and Joko Wibowo Figure 8 Bearing Capacity Values (DDT) of Sandy Soil at Different Coir Fiber Percentage and Length It can be seen from Figure 8 that the soil bearing capacity is directly proportional to the CBR value (Figure 7). Where the condition is unsoaked, soil bearing capacity value increases along with the addition of fiber percentage, but the highest carrying capacity value occurs in sandy soil mixture with fiber length 1,5-2 cm. So it can be concluded that the longer fiber cm provides better bearing capacity than the cm fiber length. The same trend is also seen in soaked conditions. From Figure 8 it is also seen that under soaked conditions, soil bearing capacity tends to increase up to a certain percentage of fiber, then soil bearing capacity decreases with fiber addition. Based on the graph, the percentage of coco fiber obtained which yields the highest bearing capacity value in soaked condition is cm fiber length with 0.78% fiber percentage and the bearing capacity value is 8.6. While in soaked condition with fiber length of cm obtained fiber percentage that yield optimum bearing capacity (8,48) that is percentage fiber 0,77%. 4. CONCLUSION The addition of coco fiber to sandy soil affect to the value of CBR and soil bearing capacity. Under soaked conditions, the optimum percentage of coco fiber is 1% and cm in fiber length with maximum CBR value is 38,50 %. While in the unsoaked condition, the value of bearing capacity and CBR value are still increasing along with the addition of fiber percentage. It is also concluded that proportion of 0.78% coir fiber and 1,5-2 cm of coir fiber length in a soil is optimum percentage which is having maximum soaked bearing capacity value, which is about 8,60. Hence, this proportion may be economically used in road pavement and embankments. ACKNOWLEDGEMENTS The authors wish to express our profound gratitude to the members of staff of the soil laboratory of the Department of Civil Engineering University of Tadulako. They rendered high level of assistance during the experimental set up of the research editor@iaeme.com

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