Coir Geotextiles Research Articles

Experimental Investigations on Biological Resistance of Surface Modified Coir Geotextiles

Results of detailed experimental studies carried out to investigate the resistance of coir geotextiles modified using cashew nut shell liquid (CNSL) to attack of biological organisms are reported. A mixed spore suspension composed of four fungal stains, Chaetomium indicum, Curvularia lunata, Aspergillus fumigatus and Penicillium rubrum was used to study microbial susceptibility of coir geotextiles in humid warm atmosphere. Soil burial studies were carried out under controlled conditions for a period of 240 days to learn the behaviour of geotextiles in contact with specially prepared soil containing a variety of microorganisms. A field study was carried out to investigate the behaviour of coir geotextiles in subterranean termite mounds. The improved properties of modified coir geotextiles were substantiated on the basis of weight loss, moisture absorption, tensile strength and surface morphology. The results show that biological resistance of coir geotextiles was greatly improved by modification with CNSL. Tensile strength of unmodified samples reduced to 19 % whereas modified geotextiles retained 76 % of the initial tensile strength at the end of 240 days of soil burial. SEM images affirm that modification of coir with CNSL obtained in the present work could close the pores on fibre surface and delay biological degradation considerably.

STUDIES ON THE EFFECT OF SPACING OF COIR GEOTEXTILE ON LIME STABILISED QUARRY WASTE COLUMN

DOI: 10.5281/zenodo.60807 ABSTRACT Stone columns are massively used ground improvement technique. Installation of stone columns enhances the load carrying capacity and accelerates consolidation and thereby reduces settlement. The lateral confinements offered by the surrounding soil are inadequate to form the stone column, when installed in extremely soft soils. In such cases, the performance of stone column can be improved by lateral reinforcements. Here coir is provided as the lateral reinforcement. The present study investigates the load verses settlement response of various spacings of the coir geotextile reinforced lime stabilised quarry waste column. Four different spacings are adopted. The results revealed that the load carrying capacity of stone column is influeneced by the spacing of the reinforcemnt.

Utilizing coir geotextile with grass and legume on soil of Cerrado, Brazil: An alternative strategy in improving the input of nutrients in degraded pasture soil?

Inappropriate management practices on Cerrado soil cause some of the most important negative impacts on this ecosystem, especially converting native vegetation on pastures and crops plantation. Significantly losses of natural Cerrado have been reported and current remaining natural vegetation area is smaller than other land cover. Therefore, sustainable practices are required to recover and protect the biome. For that reason this work aimed to evaluate the effect of grass and legumes species on coir geotextile during a seasonal cycle of rain and drought on soil of abandoned pasture of Cerrado in southeastern Brazil. Several soil parameters were examined, including their physical and chemical compositions, microbial biomass-C (SMB-C), and microbial viability. The plant species used were Andropogon gayanus (CGG—Coir Geotextile Grass) and Calopogonium mucunoides and Arachis pintoi (CGL—Coir Geotextile Legumes). In general, CGL had more beneficial effects on soil fertility than CGG in terms of total soil organic carbon and total nitrogen. The CGL treatment showed SMB-C values twice those of the control, and 28% higher than CGG. Microbial populations (actinobacteria and fungi) increased in CGG and CGL, being the better improvement on microbial growth observed on CGL. Actinobacteria was the most prevalent group both on the soil surface and at greater depths. Our results indicated that Calopogonium mucunoides is a very aggressive species and inhibits the growth of Arachis pintoi. The appropriate use of geotextiles, associated with non-weed and non-alien vegetation, represents a viable technique for improving total SOC and SMB-C, nutrients as nitrogen and phosphorus, and increase the microbial populations.

Analysis of Groyne Placement on Minimising River Bank Erosion

Bank erosion is the wearing away of the banks of a stream or river. Impacts of river bank erosion are multifarious: social, economic, health, education and sometimes political. Groynes are structures constructed in rivers to protect the shore. Groynes are generally made of wood, concrete, or rock piles etc. In the present study coir geotextiles in the form of cocologs are used as the groynes to make the groyne more ecofriendly. Study mainly concentrates on analysing the effects of placing groynes at different angles from 450 to 1350 and to find the most effective arrangement for minimising the erosion. Results indicate that cocolog-groynes are effective in minimizing the erosion and protecting the bank. Maximum protection is observed for groyne angle of 1350.

Numerical Modeling for the Selection of Coir Geotextile for Erosion Control Application Based on the Universal Soil-Loss Equation

AbstractA fuzzy logic–based modeling approach using the universal soil-loss equation (USLE) along with selection and application of the appropriate coir geotextile (CG) in soil erosion control was attempted in this study. The fuzzy logic model was developed to address issues of soil erosion risk with constant rainfall intensity. Two simple and efficient fuzzy logic soil erosion models were developed, of which one was for predicting soil erosion intensity (fuzzy-soil erosion model, or F-SEM) and the other was for selecting an appropriate CG type for soil erosion control based on types of soil in various combinations of slope angle and length, crop cover, rainfall intensity, and so forth (fuzzy-CG model, or F-CGM). These two models were developed in such a way that the input data requirement was the minimum for model execution. The considered input parameters were the main primary governing factors that influence soil erosion intensity in the USLE platform. F-SEM and F-CGM was compared with actual field dat...

Effects of the climatic conditions of the southeastern Brazil on degradation the fibers of coir-geotextile: Evaluation of mechanical and structural properties

In tropical countries where rainfall rates are high, and especially in deforested areas in the Atlantic Rainforest and Cerrado in southeastern Brazil, water is the dominant driving force of erosion. The most common method used to restore degraded tropical lands is to plant nursery-raised tree seedlings, but this method is not always practical and a variety of newer reforestation techniques have become available. Biodegradable coir geotextiles combined with native seeds can be used to restore degraded forest areas. The effects of the climatic conditions during a seasonal cycle of rain and drought were evaluated on the structural and mechanical properties of coir geotextile fibers that were treated, or not, with lime. Analyses of the tensile strength of coir fibers showed that after 12 months of exposure untreated fiber had retained 23% and treated fiber 19% of their initial strength. Two principal factors were considered in evaluating the structural properties of the coir fibers after environmental exposure: (i) initial cellulose retention and its stability after lime-treatment; (ii) lignin degradation and/or its loss to the environment. The structural changes seen by thermogravimetry (TGA) and Fourier Transforms in Infrared spectroscopy (FTIR) analyses explained the changes seen in coir mechanical properties. The greater cellulose contents of fiber structures treated with lime explained their greater tensile strength and high Young's modulus measures after the first three months of exposure in local weather conditions. Considering that lime treatment improved coir fiber properties, lime applications are indicated when coir geotextiles are to be used in acidic Brazilian Cerrado soils.

REVEGETATION OF DECOMPOSED GRANITE ROADCUTS IN KOREA: DEVELOPING DIGGER, EVALUATING COST EFFECTIVENESS, AND DETERMINING DIMENSIONS OF DRILLING HOLES, REVEGETATION SPECIES, AND MULCHING TREATMENT

ABSTRACTDecomposed granite roadcuts are difficult to revegetate after losing the topsoil and vegetation cover. We developed a new drilling machine, Digger, to efficiently drill six holes simultaneously on decomposed granite roadcuts to facilitate revegetation. The Digger consists of a base machine (0.7 m3‐level excavator) and a mounting body with six hydraulic motors instead of a bucket. We tested its performance on two roadcuts in southwest Korea using time‐motion studies, which showed that the Digger can drill 240 m2 of decomposed granite roadcuts daily. The unit cost of the Digger was less than a half of other roadcut stabilization and revegetation techniques in Korea, making the Digger a cost‐effective revegetation technology. Field germination and growth tests were also conducted to identify appropriate diameter and depth of drilling holes, suitable revegetation species, and mulching treatment. We drilled holes with three different diameters and depths, filled the holes with a mixture of plant seeds and cultivated soil, applied mulching treatments (coir geotextile, shade net, and no mulching), and measured the germination and growth results at two field plots after 1 month and 1 year. The results showed that drilling diameter 10 cm and depth 10 cm were large enough to result in better plant germination and growth. Erosion control species, Poa pratensis L. and Eragrostis curvula (Schrad.) Nees, survived and grew better than native woody species. Coir geotextile improved the plant germination and growth. The time‐motion and revegetation results show that the Digger can be a promising technology to restore decomposed granite roadcuts. Copyright © 2013 John Wiley & Sons, Ltd.

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.

Biodegradation of Coir Geotextiles Attached Media in Aerobic Biological Wastewater Treatment

Coir is a hard and tough organic fibre, rich in cellulose and lignin, and possesses high specific area and wetting ability - factors which are important for bacterial adhesion in fixed film processes. Few studies have been reported on the durability of coir geotextiles, when used in Civil Engineering applications such as slope protection works. However, its durability when used as the media in biofilters, for wastewater treatment extensively has not been studied yet. Durability of coir geotextiles has been assessed by keeping it in wet condition and measuring the tensile strength of the fibres, at different times. In the present study, coir geotextiles that were used as the attachment media in a biofilter, for treatment of organic rich wastewater was tested for durability. The units were operated as aerobic, gravity flow filters. Different wastewater parameters were employed in each of these runs. Tensile strength of the fibres was determined after each run. Results show that loss of tensile strength (or degradation) is influenced by the characteristics of the effluent wastewater to the filter, due to the growth of microorganisms which depends upon the concentration of substrates in the wastewater. Permeability studies shows reduction in permeability, is influenced by the organic loading rate on the filters and the duration of filter operation. SEM studies and E-DAX analysis shows the biodegradation of the fibres constituents, influenced by the substrate concentration.

Coir geotextile for slope stabilization and cultivation – A case study in a highland region of Kerala, South India

A sloping field is not only vulnerable to soil erosion it may also suffer from soil moisture deficiency. Farmers that cultivate on slopes everywhere face similar problems. Conservation technologies may reduce soil and nutrient losses, and thus enhance water holding capacity and soil fertility. But although these technologies promote sustainable crop production on steep slopes, the construction of physical structure such as bench terraces are often labour intensive and expensive to the farmers, since construction and maintenance require high investments. Here we studied the efficiency of coir geotextile with and without crop cultivation in reducing soil moisture deficiency on marginal slopes in Kerala, India. From the results it is evident that the slopes treated with geotextile and crops have the highest moisture retention capacity followed by geotextiles alone, and that the control plot has the lowest moisture retention capacity. As the poor and marginal farmers occupy the highland region, this method provides an economically viable option for income generation and food security along with slope stabilization.

Effect of Rock Phosphate on Nutrient Status and Nut Load of Mature Coconut in South-Western Ghana

The effect of rock phosphate on mature coconut was evaluated from 2004 to 2010 within the context of low nut yield due to phosphorus deficiency in the acidic soils of South-Western Ghana. A low reactive Togo rock phosphate containing 25.5% P205 was applied. Three application schedules based on 666 kg/ha rock phosphate and a control were evaluated in a Randomized Complete Block Design with five replications. The application schedules were: (a) Bulk application at 4.5 kg/tree (b) Two-equal-split application at 2.25 kg/tree in years 1and 3 (c) Three-equal-split application at 1.5 kg/ tree in years 1, 2 and 3. Muriate of potash fertilizer was applied at 2 kg/tree as basal treatment. Plot size was 0.2 ha comprising 30 trees. Nut load and leaf nutrient status of coconut palms were determined. Rock phosphate led to a significant (P<0.01) increase in leaf phosphorus and nut yield. It sustained a superior nut load for a 4-year period beginning from year 2 of application to year 5 with average nut gain of 19.0 per tree compared to 4.6 per tree in the control palms. There was no significant (P>0.05) difference in nut yield and nutrient status between bulk and split methods of rock phosphate application. A value-to-cost ratio of 1.5 was obtained thus indicating the profitability of rock phosphate application in the acidic soils of South-Western Ghana. Coir geotextiles find application in revegetation of slopes by stabilizing the soil through erosion control. It has been found that the longevity of coir geotextiles although highest among all the natural fibres, it is required to last for at least 5 years so as to sustain the vegetation on the slopes for a long term solution. Normally it is found that coir geotextiles lose their 50% strength in 6 months in contact with soil, therefore it is required to strengthen the coir geotextiles.

Enhancement of Properties of Coir Geotextiles by Natural Rubber Latex Coating

Coir geotextiles find application in revegetation of slopes by stabilizing the soil through erosion control. It has been found that the longevity of coir geotextiles although highest among all the natural fibres, it is required to last for at least 5 years so as to sustain the vegetation on the slopes for a long term solution. Normally it is found that coir geotextiles lose their 50% strength in 6 months in contact with soil, therefore it is required to strengthen the coir geotextiles.
 This work involves the coating of coir geotextiles with natural rubber latex which could enhance the longevity of coir geotextiles in various civil/bio engineering applications. The rubber latex coated coir geotextiles which are eco-friendly have superior mechanical properties and better durability compared to the conventional uncoated coir geotextiles.
 This paper reports the coating of coir geotextile using natural rubber latex and a comparative study of the physical and mechanical properties of the treated and untreated coir geotextiles.

Use of coir geotextiles in unpaved road construction

ABSTRACT: This paper reports the beneficial effect of five varieties of coir product inclusion (three types of woven coir geotextile and two types of hand-knotted coir netting) on the California bearing ratio (CBR) behaviour of four soils: a natural soft clay; a commercially available soft clay; lateritic soil; and sand over soft clay subgrade. The study indicates that CBR improvement sufficient to eliminate the need for a strong base course in unpaved roads is achievable through the use of these coir products. Woven coir geotextiles are found to perform much better (about a twofold improvement) than hand-knotted coir nettings (about a 1.5-fold improvement). Lateral confinement of the soil within the cells of the geotextile/netting is identified as the principal reinforcement mechanism. The general strength mobilisation theory applicable to geosynthetic reinforcements, according to which the lower the CBR value of the subgrade is, the higher is the degree of improvement due to reinforcement inclusion, is not valid for coir geotextiles and nettings. The paper also highlights the importance of testing under soaked conditions, even for non-swelling soils.

Standardization of Test Procedure for Tension Test on Coir Yarns and Woven Coir Geotextiles

Abstract This paper presents the results of an experimental investigation conducted to develop a standard test procedure for tension testing on coir yarns and woven coir geotextiles. Uniaxial tension tests were conducted on nine types of woven coir geotextiles and eleven types of coir yarns. Specimens of different dimensions were tested at various deformation rates. Test results indicated that tensile properties of coir yarns and geotextiles were largely influenced by testing parameters. Statistical analysis of yarn tension data was carried out to establish the gauge length, strain rate, and specimen dimensions of geotextiles. Consistent values of tensile strength and failure strain were obtained when gauge length and strain rate were adopted as 150 mm and 5 %/min, respectively. It was also observed that reliable results were obtained when the width of the geotextile specimen for tension test contained not less than ten yarns.

Characterisation of natural geotextiles

This paper presents the characterization of natural geotextiles along with their physical & mechanical properties and influence of deformation rate. The results presented in this paper reveal that the thickness of natural geotextiles can be taken as that corresponding to normal pressure 2 kPa after 1 minute of application of pressure. Compressibility of non-woven geotextiles is significantly higher than that of woven geotextiles. A change in deformation rate from 10 to 300 mm/min, there is no change in strength, for natural geotextiles, except for the non-woven. The tensile strength of natural geotextiles can be taken as that corresponding to 200 mm wide × 100 mm length specimen at a deformation rate of 10 mm/min, for all practical purposes. The woven coir geotextiles have more tensile strength in the machine direction than in the cross-machine direction. Their tensile strength is influenced by number of yarns. The non-woven coir geotextiles have more tensile strength and tensile elongation in the machine direction than in the cross-machine direction. The behaviour of the non-woven coir geotextiles is influenced by the presence of the type of stitching, yarn used, coir/jute netting and the coir web weight. The variance in tensile strength and tensile elongation of the non-woven coir geotextiles is generally more in comparison to woven coir geotextiles.

Laboratory performance of unpaved roads reinforced with woven coir geotextiles

The results of an experimental study conducted to investigate the beneficial use of woven coir geotextiles as reinforcing material in a two-layer pavement section, are presented. Monotonic and repeated loads were applied on reinforced and unreinforced laboratory pavement sections through a rigid circular plate. The effects of placement position and stiffness of geotextile on the performance of reinforced sections were investigated using two base course thicknesses and two types of woven coir geotextiles. The test results indicate that the inclusion of coir geotextiles enhanced the bearing capacity of thin sections. Placement of geotextile at the interface of the subgrade and base course increased the load carrying capacity significantly at large deformations. Considerable improvement in bearing capacity was observed when coir geotextile was placed within the base course at all levels of deformations. The plastic surface deformation under repeated loading was greatly reduced by the inclusion of coir geotextiles within the base course irrespective of base course thickness. The optimum placement position of coir geotextile was found to be within the base course at a depth of one-third of the plate diameter below the surface.

Experimental investigations on tensile and pullout behaviour of woven coir geotextiles

Results of an experimental programme to investigate the tensile and interface properties of woven coir geotextiles are presented. Tension tests were conducted on coir fibres, yarns and woven geotextiles at different gauge lengths and strain rates. Based on statistical analysis, a gauge length of 150 mm and a strain rate of 5%/min was adopted for the purpose of characterization of tensile properties. Tensile strength of woven coir geotextile was expressed as a function of fibre strength, yarn properties and weaving pattern. Pullout test and modified direct shear test were conducted on geotextiles in granular soils of different grain sizes. At low normal stress, bond resistance of coir geotextile–sand interface obtained was more than shear strength of soil. But consistent values of bond resistance were not obtained at higher normal stresses. The opening size of mesh relative to the soil grain size influenced the pullout interaction between soil and geotextile. For closely woven geotextiles, the pullout resistance did not vary much in soils of different grain sizes, whereas for geotextiles with open meshes, pullout resistance obtained was more in fine sand compared to coarse sand.

Testing coir geotextile drains for soft ground improvement

The results of an experimental investigation to explore the effectiveness of coir geotextile vertical drains for ground improvement are reported. The time settlement behaviour of clayey soil, as influenced by coir geotextile drains, is summarised and the construction and installation details are also discussed. Two types of coir drains, a circular type and a rectangular type, using two varieties of coir geotextiles were tested in three configurations, namely a single drain and triangular and rectangular patterns. It was observed that the time for consolidation was very much reduced due to the installation of coir drains irrespective of the type of coir geotextile used, type of coir drain and the layout of the drains. Furthermore, in addition to ease of construction these drains are eco-friendly and will not pose any environmental problems.

Participatory research using coir geotextiles in watershed management – A case study in south India

This paper deals with participatory research on the introduction and use of coir geotextiles for soil and water conservation in a small community pond in a watershed in south India. The results demonstrate that a participatory approach enables the community to visualize and evaluate the impact of innovative technologies. As a result, farmers readily adapt a technology when they have experienced the positive research outcome. This reduces the adoption time, and can bring significant increase in yield, or decrease in labour costs, helping to enhance productivity, sustainability and improvement of livelihood.