• High moisture absorption capacity

• Flexibility

• Drainage properties

GeoJute finds Applications in -

• Erosion control

• Separation, filtration and drainage in civil engineering works

• Agricultural uses

Advantages :

• Abundant availability

• Superior drapability

• Greater moisture retention capacity

• Lower costs compared to synthetic geotextiles

• Ease of installation

• Bio-degradable properties

Feature Article :........ J U T E ..G E O T E X T I L E S

Geotextiles have seen unrivalled growth with a forecast by the United Nations International Trade Centre (UNITC) of 1,400 million m² produced by the new millenium. Europe and North American markets each account for 40% with the remaining 20% attributed to Japan, Asia and Australasia. The main applications are separators in earth works, drainage and linings as well as controlling soil erosion and establishing plant growth.

As jute accounts for such a small proportion of geotextile use in the West there is enormous scope for increased usage. Most land managers in Europe are generally unaware of the relevance of jute products, as they consider textiles as the main output of the industry. Jute accounts for less than 1% of total geotextile use, despite the technical advantages and low cost of jute geotextiles, which has been demonstrated by research and the results of full-scale use. A promotion programme which aims to provide product information in readily useable form has been initiated by UNITC, UNDP and JMDC.

Conservation land managers, landowners and landscape architects who use jute in environment projects will see immediate improvements in the rate and quality of vegetation growth, as well as greatly reduced material costs.

Two seminars in London and Geneva last year brought together key jute producers with invited researchers, environmental consultants, suppliers, contractors and specifying authorities. Specifications were agreed which jute geotextiles would need to meet to satisfy environmental and geotechnical engineers. The obvious uses in erosion control were generally known, but it was interesting to note that composite products involving jute in combination with synthetics, or jute together with coir, can offer optimum solutions in other areas. Some applications are clearly suited to jute, but the material characteristics need more elaboration. Other applications are more easily satisfied by the other types of geotextiles.

Applications :

Jane Rickson of Silsoe College identified three current main applications for jute:

• Erosion control and vegetation establishment
• Agroplant mulching
• Rural road pavement construction

The salient properties which determine the effectiveness of ageotextile are percentage cover, water holding capacity, the thickness and roughness of fibres and yarns, their orientation across the slope and installation procedures which do not disturb the site. Testing over 12 years at Silsoe has proved the technical excellence of jute compared with other natural and synthetic geotextiles under a range of environmental conditions, showing that vegetation establishment is highly effective when jute is used.

A newly developed wick drain, formed from a jute sleeve packed with coir, showed how combinations of geotextile types provide benefits greater than the sum of each. Professor Bob Sarsby of Bolton Institute reported on full-scale trials of soil walls incorporating jute rope reinforcement. This work graphically demonstrated the strength of jute in supporting walls of 4m or more. He went on to describe the use jute in road construction especially over areas of poor ground. Not enough attention has yet been paid to this potentially extensive application.

The micro-climate surrounding jute geotextiles has been explored by Yves Henri Faure of Grenoble University who has tested the efficiency of jute sheets in preventing loss of soil in shallow and steep slopes. Earth works were built on a test-bed capable of being rotated to various inclinations and subjected to simulated rainfall, varying from light to heavy tropical downpours. The amount of soil lost to erosion was measured. The faces were then protected by various geotextiles and the soil erosion again measured. The tests simulated wash out of vegetated soil slopes and provided data of use in landscaping projects. Over the whole range of rainfall intensities and slope angles jute geotextiles outshone the other materials. A jute of approximately 500g per m² appeared to be cost effective.

Using jute to protect large areas from erosion, including high-altitude ski-slopes with significant precipitation, has been trialed by Francoise Dinger of CEMAGREF. The ability of jute to absorb five times its own weight of water ( 3kg per m² of slope ) was demonstrated. The retained water firstly attenuates the run-off into the drainage system and is then released gradually to soak into the adjacent soil to nourish the vegetation from severe frosts, so aiding growth.

Mike Hyder of Hy-Tex Ltd. commented that prevention of soil erosion was better and more cost effective than remedial works. The most vulnerable sites were over steepened slopes, exposed highly erodible sub-soil, and disturbed or badly compacted ground.

Consequences of soil erosion were: poor growing conditions, additional costs for remedial works, blocked drains and flooding, pollution of waterways and increased maintenance. Many applications of jute made by his company were illustrated by ‘before and after’ photographs showing the dramatic improvement in vegetation growth and erosion control.

Barbara Lois of SIRAS Company described the extensive environmental works undertaken in France using jute geotextiles, including rehabilitating mine dumps, restoring the Rhone river banks and the vegetating high altitude steep slopes at the Winter Olympic ski jump in Savoie. Landscaping of slopes alongside the TGV rail line and along highway cuttings and embankments showed the effectiveness of the geotextiles.

Dr. Finn Terkelsen from Denmark felt that the partners in this field are playing a waiting game. The jute mills are waiting for the engineers to tell them what to do, whilst the engineers are waiting for the jute mills to show them what is available. Much research has been carried out by several institutes in jute producing countries as well as in Europe. Interesting results were seen but wider use did not materialise. It will be important to address this issue and to use past experiences as stepping stone for future work. There is currently a very wide gap. Erosion control, foundations, sound barriers, filters, and reinforcement and drainage were suggested as the most appropriate target uses of jute geotextiles.

Costs :

Whilst the cost of geotextiles (selling in Europe for £ 0.40 to £ 0.80 per m² ) is lower than synthetic geotextiles ( £ 1.10 to £ 1.35 per m² approx) and other natural fibre geotextiles (£ 0.75 to £ 2.00 per m²) their usage is very low. S.K.Bhattacharya of the Indian Jute Mills Association stressed jute was competitive on price, and other delegates commented that technical characteristics were also superior to other materials in particular applications.

Jute degrades in over 2 to 4 years, but this is usually a sufficiently long period for vegetation growth to become established, and trials have shown that degraded by-products are beneficial plants. Work is progressing to produce treated jute which has a longer life before degradation.

Steep Slopes :

Steep slopes present particular erosion control problems. Eight soil erosion plots were established on a South facing slope in a trial carried out by Dr.David Mitchell of Wolverhampton University Experimental Station at Hilton, Shropshire. Soil erosion of sections protected slope reduced the erosion by 54% whereas the jute geotextile reduced erosion by 99% compared with the bare slope.

Using jute to resolve the difficulties of vegetating the steep faces of reinforced soil slopes would be helped if the salient technical aspects were drawn together and published in a form more accessible to users. For example, jute blended with synthetic fibres has been processed on the existing non-woven production machinery at British Textile Technology Group (BTTG), ManchesterA range of technical products of widely varying properties and with weights from 100 to 2000gm per m² and with thicknesses up to 60mm can be produced by this method.

Future Links :

The two seminars held in London and Geneva in 1997 under auspices of JMDC forged links between all sides of industry which will be instrumental in helping jute to be accepted and applied more widely in environmental schemes. The clear need for concise technical information of direct relevance to users was established and the next phase of the work will address this.

Note: This is reproduction of an article written by Mr. Red Smith, Director, Elwood Consultants Ltd., Albrighton (UK) which was published in the Autumn’98 issue of ENACT , a UK-based land management magazine. JMDC utilised the expertise of Mr. Rod Smith for promotion of jute geotextiles in Europe.

(Sourse : INDIAN JUTE newsletter, March 1999)