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Abstract
Geotextiles form one of the two largest groups of geocynthetics. Their rise in growth during the past fifteen years has been nothing short of awesome. They are indeed textiles in the traditional sense, but consist of synthetic fibers, thus biodegradation is not a problem. These synthetic fibers are made into a flexible, porous fabric by standard weaving machinery or are matted together in random, or nonwoven, manner, some are also knit. The major point is that they are porous to water flow across their manufactured plane and also within their plane, but to a widely varying degree. There are at least eighty specific applications area for geotextiles that have been developed; however, the fabric always performs at least one of five discrete functions: separation, reinforcement, filtration, drainage and protection.
This study is an attempt to improve the efficiency of agricultural covered drainage system. An envelope was designed as a porous media to allow the flow of water and to restrict the soil particles.
The research went into two directions; the first one was to study the basic subsurface drainage principles and design guidelines for textile envelope, the second one was to design and test the new geotextile envelopes.
This work depends on recycling the waste and reuse it in nonwoven envelope production. Recycling the waste is the most important application of cleaner production assessment.
Depending on the previous studies, the design idea was set to use for different basic materials in drainage. Three different materials of non- woven fabrics were used as follows:
•Class A and A/H: 75/25% waste/ virgin p.p.
•Class B and B/H: 50/50% waste/ virgin p.p.
•Class C and C/H: 100% virgin p.p.
These samples were produced by needle punched technique.
The designed envelopes were divided into two main groups the first normal (non-treated samples) and the other were the heat treated samples. All were produced in three different weights and thicknesses. Designed envelopes were tested for evaluating two basic functions as follows:
1-The hydraulic function which involved three basic criteria: in plane flow permeability, cross plane flow permeability and pore size index O90.
2-The mechanical function which involved four basic criteria: tensile strength (M.D and C.D), elongation at break (M.D and C.D), tear resistance (M.D and C.D) and burst resistance.
The results of tested samples were then evaluated according to the Egyptian standard of synthetic envelope and the economical and environmental aspects.
Through the evaluation of the results, it was found that the best recommended envelopes were the untreated samples of class B Nos. (1-2- 4-6-9) followed by the treated samples class B/H Nos. (3-4-6-9) and finally the treated samples class A/H Nos. (7-8).
On the other hand the untreated samples class A Nos. (4-1-2-3-5), treated sample class A/H No. 4 and untreated sample of class B No. 3 had been excluded because of their weak mechanical properties.
The Egyptian standard for mechanical properties of envelopes used with the trenchless machine was found to be achieved by the untreated sample class C No. 7 and the treated samples class C/H Nos. (7- 8-9).