Woven Coir Research Articles

Dewatering and stabilization of Black cotton soil using Electrokinetic Geosynthetics

Electrokinetic Geosynthetics (EKG) is a platform technology used to dewater and stabilize highly saturated soft clayey soils, mine tailings, tunnelling slurry waste, sewage sludge etc. This laboratory study investigates the potential of EKG made of woven coir geotextile to stabilize highly expansive saturated black cotton soil collected from the Hubli-Dharward region of Karnataka state, India. An electoosmosis design was made in a tank setup where the soil was dewatered for a period of 7 days under three varying potential (15V, 30V & 60V) and different electrode configuration. The results demonstrated an increase in the rate of pore water dissipation by 500% at an optimum voltage gradient of 30V in various electrode spacing. The results of the EKG treatment at various voltages revealed that, as applied voltages increased up to 60 V, the liquid limits and plasticity indices rapidly dropped. An exponential increase in undrained shear strength of the soil was observed at an electrode configuration of 4A-1C.

Effects of cyclic loading on sand overlaying clay model of unpaved roads reinforced with untreated/treated coir geotextiles

The current study examined the application potential of the untreated/treated woven/non-woven coir geotextile on unpaved roads. For this, untreated/treated coir geotextiles were positioned at the interface under the unsoaked/soaked condition, and laboratory cyclic load tests were done in a test tank for the sand layer overlying the clay layer. The results of the study showed that models reinforced with untreated/treated woven coir geotextiles are better than the models with untreated/treated non-woven coir geotextiles. Furthermore, in comparison to the soaked condition, models reinforced with untreated/treated woven and non-woven coir geotextiles show better improvement in plastic deformation in the unsoaked condition. When placed at the interface of the sand layer overlying clay, untreated/treated woven/non-woven coir geotextiles can reduce plastic deformation in unpaved roads, especially in situations where the rut depth is high, as the improvement in plastic deformation was realised up to larger deformation.

Improvement in the performance of two layered model pavement with treated coir geotextile at the interface

The primary objective of this research work is to study the effect of surface treated coir geotextiles on the bearing behaviour of sand overlying clay model with geotextiles at the interface. Two woven and two non woven coir geotextiles were treated with bitumen emulsion and unsaturated polyester resin. The surface morphology and thermal stability were investigated by scanning electron micrograph and simultaneous thermal analyser respectively. The bearing ratio of sand overlying clay increased with treated woven/non woven coir geotextiles at the interface in soaked and unsoaked condition. The bearing ratio was higher for treated/untreated and woven/non woven coir geotextiles at the interface in unsoaked condition as compared to soaked condition. The chemical treatment improved the thermal stability of surface treated coir geotextiles through physical and chemical changes.

Investigation on tensile strength characterisation of untreated and surface treated coir geotextiles

The present study investigates the effects of chemical treatment in characterising the physicomechanical properties of coir geotextiles. Two woven and two non woven coir geotextiles were used in this study. All four types of coir geotextiles were chemically treated with unsaturated polyester resin and bitumen emulsion. The results reveal that the tensile strength of untreated and treated woven and nonwoven coir geotextiles was higher in the warp/machine direction as compared to the weft/cross-machine direction respectively. The chemical treatment increased the tensile strength and decreased the tensile elongation of both woven and non woven coir geotextiles respectively. The chemical treatment modifies the surface morphology of both the woven and nonwoven coir geotextiles.

Studies of Modulus of Resilience on Unpaved Roads Reinforced with Untreated/Treated Coir Geotextiles

ABSTRACT Using the repeated or cyclic load test in a laboratory, the current study investigates the modulus of resilience of unpaved roads model reinforced with untreated/treated woven/non-woven coir geotextile. P-aminophenol, sodium periodate, and sodium hydroxide were the chemicals that used to treat the coir geotextiles. Untreated/treated coir geotextiles were placed at the interface under unsoaked/soaked conditions, and laboratory cyclic load testing for the sand layer overlaying clay was performed in a test tank. Models reinforced with untreated/treated woven coir geotextiles performed better than models reinforced with untreated/treated non-woven coir geotextiles, according to the study’s findings. Furthermore, in the unsoaked state, models reinforced with untreated/treated woven and non-woven coir geotextiles better than the models reinforced with soaked coir geotextiles in terms of modulus of resilience. Untreated/treated woven/non-woven coir geotextiles can increase the material’s maximum energy per volume that it can absorb in unpaved roads when placed at the interface of the sand layer overlying clay. This study is very beneficial, especially in situations where highway subgrade design necessitates a reasonably accurate estimation of strength and stiffness characteristics.

Bearing Ratio Behavior of Sand Overlying Clay with Treated Coir Geotextiles at the Interface

ABSTRACT The paper presents the bearing ratio behavior of sand overlying clay with two woven and two non-woven treated coir geotextiles at the interface. The chemicals such as p-aminophenol, sodium periodate and sodium hydroxide were used to treat the coir geotextiles. The results indicated that the unsoaked/soaked bearing ratio of the sand overlying clay with woven coir geotextiles at the interface decreased after the chemical treatment whereas the trend was reverse in case non-woven geotextiles. The unsoaked bearing ratio of the sand overlying clay with the treated/untreated woven and non-woven coir geotextiles at the interface was higher than the soaked bearing ratio. The C: O ratio both for the woven and the non-woven coir geotextiles increased after the chemical treatment. The emissions of Si increased for the woven coir geotextiles whereas it decreased for the non-woven coir geotextiles after the chemical treatment. The chemical treatment results in the modification of the surface of both the untreated woven and non-woven coir geotextiles.

CHARACTERIZATION, DURABILITY, AND APPLICATION OF TREATED COIR GEOTEXTILES IN LOW VOLUME ROADS

ABSTRACT A study was conducted to investigate the effects of chemical treatment in characterizing the tensile strength, durability, and application of untreated/treated coir geotextile in low-volume roads. Two woven and two nonwoven coir geotextiles were used in this study. Sodium hydroxide and potassium permanganate were the chemicals used to treat the coir geotextiles. The results show that the tensile strength of both the woven coir geotextiles treated with potassium permanganate was lower as compared to both the untreated woven coir geotextiles. The tensile strength of both the nonwoven coir geotextiles treated with sodium hydroxide was higher as compared to both the untreated nonwoven coir geotextiles. Further, the tensile strength of both the woven as well as nonwoven coir geotextiles treated with potassium permanganate was higher in comparison to the one treated with sodium hydroxide. The tensile strength of both the woven as well as nonwoven coir geotextiles first treated with sodium hydroxide followed by potassium permanganate was higher as compared to both the woven as well as nonwoven coir geotextiles treated with sodium hydroxide and potassium permanganate individually. The percentage reduction in tensile strength due to deterioration in the cross-machine direction for both the woven and nonwoven coir geotextiles was higher as compared to the direction of the machine. The results of monotonic load tests show that the models reinforced with untreated/treated woven and nonwoven coir geotextiles show an increase in the bearing pressure at greater deformation. Untreated woven/treated nonwoven coir geotextiles placed at the interface of the sand layer overlying silty sand can be useful in the low-volume roads.

Effect of Chemical Treatment on the Durability Behavior of Coir Geotextiles

ABSTRACT The paper presents the effect of chemical treatment on the durability study of untreated/treated woven/non-woven coir geotextile. The p-aminophenol, sodium periodate, and sodium hydroxide were used for the treatment of the coir geotextiles. For this, laboratory wide width tensile strength test was conducted in a universal testing machine for untreated/treated woven/non-woven coir geotextile placed at the interface of sand-overlaying clay after the period of 2, 6, 8, 12 months, respectively. The results of this study reveal that the tensile strength decreased for the untreated and treated woven coir geotextiles with increase in the period. The reduction in the tensile strength for the woven coir geotextiles was more in the weft direction as compared to the warp direction. The reduction in the tensile strength of the treated woven coir geotextiles was more as compared to the untreated coir geotextiles. The reduction in the tensile strength for the non-woven coir geotextiles was more in the weft direction as compared to the warp direction. The reduction in the tensile strength for the untreated non-woven coir geotextile was more as compared to the treated non-woven coir geotextiles.

Performance of coir geotextile reinforced subgrade for low volume roads

Reinforcing flexible pavements using different types of geosynthetics is a technique that is widely used to increase the service life, reduce the maintenance costs and, guarantee high performance throughout the service life. This paper presents the insights from combined experimental and numerical analysis conducted on organic soil reinforced with coir geotextiles. A series of small-scale in-box plate load tests were performed to investigate the behavior of coir geotextile reinforced high plastic organic soil under circular loading. Tests were conducted on both homogeneous (sub grade alone) and layered configurations. Two types of commercially available woven coir geotextiles viz. H2M5 and H2M6, were utilized to study the contribution of coir geotextiles when used as reinforcement at the interface of sub-base and subgrade layers in enhancing the strength and stiffness of the low volume road. The primary objective of this exploratory study is to investigate the improvement in the performance of the low volume pavement as a result of the added geotextile reinforcement. The key performance parameters, namely, displacement, stress and strain responses of both reinforced and unreinforced pavement sections are obtained by analyzing the pavement using ABAQUS, which is a software suite for Finite Element Method (FEM) analysis. Test results indicate that the coir geotextile reinforcement substantially improved the performance of high plastic organic subgrade. A maximum reduction of 38% and 24% in vertical strain was observed on top of the subgrade in the case of H2M5 and H2M6 coir geotextile reinforced sections, respectively. Also, a maximum reduction of 30% and 18% in vertical displacement was observed in the case of H2M5 and H2M6 coir reinforced sections, respectively. At an average radial distance of about 1 m from the center of simulated static wheel load, very small displacement and strain value were observed for reinforced sections, relative to the unreinforced sections. Hence, the conclusion is drawn that the H2M5 type of coir geotextile contributes more than the H2M6 type to the structural performance improvement of pavements when used as reinforcement.

Field Evaluation of Coir Geotextile Reinforced Subgrade for Low Volume Pavements

ABSTRACT This investigative study focuses on the response of full scale coir reinforced low volume roads when subjected to static loading. The test track of 1.736 km consists of a control section and eight reinforced sections including two types of coir geotextiles and subbase with varying thickness. An assessment of the general behavior of coir geotextile-reinforced sections, to static plate load tests, California Bearing Ratio tests, geogauge and dynamic cone penetration tests is done for evaluation. The study summarizes the results of the executed tests on the reinforced test track in comparison to the unreinforced one. The results reveal that the geotextile with higher apparent opening size is not as good as that of the finer mesh geotextile. A maximum of 112% improvement in the elastic modulus of subgrade is achieved by using a woven coir geotextile of 740 g/m2 mass per unit area whereas 70% increment is attained while using an alternate geotextile of 365 g/m2 mass per unit area. The elastic modulus values are determined from the various field tests and the overall damage analysis is carried out using KENPAVE software. From the analysis, it is noted that an appreciable decrease in the aggregate layer thickness is achieved by using coir geotextile as reinforcement. Use of coir geotextiles in pavements as a reinforcement can therefore help in reducing the demand and consumption of fast-depleting natural resources.

Effect of Chemical Treatment of the Coir Geotextiles on the Interface Properties of Sand–/Clay–Coir Geotextile Interface

The paper presents the effect of untreated and chemically treated coir geotextiles on the interface properties of sand–/clay–coir geotextile interface. For this purpose, two woven and two non-woven coir geotextiles were used. The chemicals used for the treatment of coir geotextiles were p-aminophenol, sodium periodate and sodium hydroxide. The results indicated that the adhesion at the clay–/sand–coir geotextile interface with treated woven coir geotextiles was higher in comparison with the untreated woven coir geotextiles. The interface friction angle at the clay–/sand–coir geotextile interface with the treated woven coir geotextiles was less in comparison with the untreated woven coir geotextiles. The adhesion as well as interface friction angle at the clay–/sand–coir geotextile interface with treated non-woven coir geotextiles was higher in comparison with the untreated non-woven coir geotextiles. For the sand–coir geotextile interface with untreated non-woven coir geotextiles, the observed adhesion as well as interface friction angle was higher in comparison with the clay–coir geotextile interface. For the sand–coir geotextile interface with untreated woven coir geotextiles, the observed adhesion was less in comparison with the clay–coir geotextile interface, whereas the interface friction angle was higher for the sand–coir geotextile interface in comparison with the clay–coir geotextile interface.

Effect of Chemical Treatment on the Tensile Strength Behavior of Coir Geotextiles

ABSTRACTThe present study investigates the effects of chemical treatment on the tensile strength behavior of the two woven and two nonwoven coir geotextiles. The results reveal that tensile elongation at failure for the untreated and treated woven and nonwoven coir geotextiles was higher in the warp direction in comparison to the weft direction. The tensile elongation at failure for the untreated and treated woven coir geotextiles were influenced by the stiffness and the opening of kinks in the coir yarn whereas the tensile elongation at failure of the untreated/treated nonwoven coir geotextiles was influenced by the presence of the polyethylene (PE) yarn used in stitching along with PE netting and diameter of the yarn used in PE netting. The chemical treatment decreased and increased the tensile strength of both the woven and nonwoven coir geotextiles, respectively. The mass per unit area of woven coir geotextile decreased whereas it increased for both the nonwoven coir geotextiles after the chemical treatment. The chemical treatment modifies the surface characteristics of both the untreated woven and nonwoven coir geotextiles due the removal of impurities and filling up the voids present on the surface.

Ballistic Impact Response of Woven Hybrid Coir/Kevlar Laminated Composites

The effects of different laminated hybrid composites stacking configuration subjected to ballistic impact were investigated. The hybrid composites consist of woven coir (C) and woven Kevlar (K) layers laminated together. The samples of woven coir were prepared using handloom device. The composites were produced by stacking the laminated woven coir and Kevlar alternately with the presence of the binder. The samples were tested under ballistic impact with different stacking configuration. The results obtained had successfully achieved the National Institute of Justice (NIJ) standard level IIA with energy absorption of 435.6 kJ and 412.2 kJ under the projectile speed of between 330 m/s and 321 m/s respectively. Samples that having Kevlar layer at the front face and woven coir layer as back face achieved partial penetration during projectile impact. This orientation is proven to have good impact energy absorption and able to stop projectile at the second panel of the composites.

Effect of Alkali Treatment and Molding Temperature on Flexural and Impact Properties of Coir-Fibre-Epoxy Composite

The combined effects of alkali treatment and compression molding temperature on the flexural strength and impact resistance of woven coir fibre composites are investigated. Ten pieces of composites plates made from single-layer woven coir fibre fabricated under different process parameters were used in the study. Five pieces of the coir woven fibre were treated with 6% sodium hydroxide (NaOH) solution while another five were left untreated. The compression molding temperature were varied between room temperature (25°C), 50°C, 75°C, 100°C and 125°C. The flexural properties of the composite were evaluated using the three-point flexural test, while the impact resistance was investigated by drop weight impact tests using a specially designed indenter. The indentation radius on each test specimen was measured using a 3-D metrology system and the depth of indentation was determined from the geometry of the indenter. The results show that the maximum flexural load to failure is improved by 38.9% when the fibres were treated and the compression molding temperature is increased to 125°C. The flexural modulus generally decreased with increase in the molding temperature. The depth of indentation in the treated coir woven composites is lower than that of untreated fibre composite at all molding temperatures. The impact resistance of both untreated and treated fibre composites decreased with the increase in the compression molding temperature. Composites fabricated by molding at room temperature, 50°C and 75°C using treated fibre produced the best impact properties.

Mechanical and machinability behaviors of woven coir fiber-reinforced polyester composite

The research on coir-polyester composites initiated the interest in the development of woven coir fiber-reinforced polyester composites. The mechanical properties of woven coir-polyester composites were evaluated as per ASTM standards and the machinability behavior was studied by conducting drilling tests in this investigation. The woven coir-polyester composites exhibited the average values of tensile, flexural and impact strength of 19.9 MPa, 31.3 MPa and 49.9 kJ/m2 respectively. The effect of NaOH treatment on the improvement of mechanical properties of woven coir-polyester composites were studied in this investigation. The 40 % increase of tensile strength, 42 % increase of flexural strength and 20 % increase of impact strength were achieved by treated woven coir fiber-reinforced polyester composites. The regression models for predicting thrust force, torque and tool wear in drilling of woven coir-polyester composites were developed and the effect of drilling parameters were analyzed.

Influence of Woven and Cross-Ply Laminates on Mechanical Properties of Coir Epoxy Composite

This research work was concerned with the evaluation of mechanical properties; flexural strength and impact strength of coconut coir textile composites. The coir fabric reinforcement was in a form of woven and cross ply structure. The two types of laminates orientations for cross-ply structures were 0/90 degrees and 45/-45 degrees. Composites with fibre weight fraction of 30% were prepared by hand lay-up and vacuum bagging technique. Mechanisms of composites failure were examined using scanning electron microscopy (SEM). Results have shown that the woven coir reinforced composites exhibited higher impact resistance and flexural strength (warp woven) compare to cross-ply composites. Moreover, 0/90 degrees orientations demonstrated better strength performance compare to 45/-45 degrees. However, damage propagation on woven composites was found to be larger than cross-ply composites. Normality test of data distribution were evaluated using Minitab software and it was proven that all samples were in a very stable behaviour (p > 0.05). Experimental results were also validated using one way analysis of variance technique (one way-ANOVA) and it revealed there was statistically significant difference (p < 0.05) between all different fabric structures of coir fabric as reinforcement in composite.

Impact and Flexural Properties of Imbalance Plain Woven Coir and Kenaf Composite

Natural fibre has become the subject of interest for research and development by various organizations due to its biodegradable and competitive mechanical properties. However most of the researchers are focusing on random orientation and compressed mat with only little researches concerned with woven or textile structure. This research work involved with mechanical analysis of woven natural fibres composite specifically coir and kenaf natural fibres. Plain woven coir and kenaf were produced from their yarns using self designed weaving device. The woven fibres were then converted as reinforcement in composite. Woven composite was prepared using manual hand lay up technique couple with vacuum bagging. Impact penetration and flexural (three point bending) test were conducted on composite sample. Morphological analysis was performed using Scanning Electron Microscope (SEM). From the results obtained, dry woven coir composite displayed better mechanical properties for both impact and flexural properties compared to kenaf composite. Warp direction of coir composite and kenaf composite showed a better flexural strength compared to weft composite direction. Coir yarn with slight lower fineness value than kenaf yarn had contributed to the higher fibre density in woven structure. The structure used as composite reinforcement in turn produced better mechanical properties.

Model studies on woven coir geotextile-reinforced sand bed

This note pertains to an experimental study made on model square footings underlain by woven coir geotextile-reinforced sand. About three-fold improvement in strength was obtained with the use of even a single layer of reinforcement, which suggests that woven coir geotextile is an appropriate material for subsoil improvement. A comparison of the results with those reported in the literature indicates that reinforced soil behaviour and the resulting strength improvement are unique for each reinforcement type and configuration. An equation that would help in obtaining strength improvement of footings on woven coir geotextile-reinforced sand is also presented. If the durability of the coir is increased, woven coir geotextiles would become a preferred material for soil reinforcement in a few countries where coir is abundantly available at practically no cost.

Behaviour of a Strip Footing on Compacted Pond Ash Reinforced with Coir Geotextiles

Pond ash, produced in huge quantities by thermal power plants, require large land area for disposal and causes environmental hazards. The pond ash can be effectively used as a fill material for low lying areas as site reclamations and in embankments. The low bearing capacity of pond ash fills can be improved by using coir geotextiles, as reinforcement which will be an eco-friendly approach. The effectiveness of horizontally placed coir geotextiles, as reinforcement in single and multiple layers, on the bearing capacity of compacted pond ash is investigated. In the present study, the bearing capacity behaviour of a strip footing on two pond ash samples reinforced with two types of woven coir geotextiles has been studied by load bearing tests in model tanks in the laboratory. The parameters varied during the tests were width of reinforcement, depth of the top reinforcement layer below the base of the footing and the number of geotextile layer. The improvement of ultimate bearing capacity was studied. The ultimate bearing capacity ratios were evaluated. A mathematical model based on the geometric parameters of the reinforcement, tensile properties of reinforcement and shear parameter of pond ash has been developed.

Model studies on woven coir geotextile-reinforced sand bed

Model studies on woven coir geotextile-reinforced sand bed