Materials. An analysis of manufacturing technology s influence on the mechanical and hydraulic properties of nonwoven geotextiles

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1 Jadwiga Malkiewicz, Robert Drobina, Stanisław Lewandowski Faculty of Materials and Environmental Sciences, Institute of Textile Engineering and Polymer Materials University of Bielsko-Biała, ul. Willowa 2, Bielsko-Biała, Poland Analysis of the Main Proerties of Geotextiles Manufactured by Mechanical Two-Sided Needle Punching and by Two-Layered Needle Punching on the Fabric Underlay Abstract An analysis of the basic roerties of geotextiles obtained by two-sided needle unching and by two-layered needle unching on the fabric underlay is resented in this aer. The influence of geotextile roduction technology on their functional roerties was evaluated, the arameters of geotextiles manufactured from stale fibres by mechanical needle unching were comared for both techniues, and the influence of the mass er unit area on the mechanical and hydraulic roerties is shown. It was found that geotextiles obtained by two-sided needle unching had very good hydraulic roerties thanks to their satial structure, whereas geotextiles obtained by two-layered needle unching on the fabric underlay, aart from good hydraulic roerties, had very good tensile strength and small elongation at a maximum load, which is articularly useful for reinforcement. Key words: geosynthetics, geotextiles, nonwowen geotextiles, mechanical needle unching technology. Introduction Geotextiles, meaning materials alied to be in contact with soil and rocks, are the largest grou of geosynthetics used in civil engineering ractice [1]. The most numerous grou of geotextiles are geononwovens roduced from stale fibres using the technology of mechanical needle-unching. The mechanism of nonwoven geofabric structure formation consists in the use of steel intertwine needles [ 4-7]. The features of geotextiles connected with their roerties of use are the effect of the resources and roduction technologies alied, which decide on the structure of the roduct. The technology of mechanical needle-unching enables the use of roducts with various roerties deending on the reuirements for drainage, filtration and searation functions of geononwovens [2, 3]. Obtaining geononwovens using the technology of mechanical needle unching by the two-sided needle unching techniue and by two-layered needle unching on the fabric underlay with the same technological and resource arameters was discussed and comared, and the roerties of the geononwovens obtained were described. The needle-unched nonwoven geotextiles are characterised by very good hydraulic roerties resulting from their considerable orosity, but simultaneously they show lower tensile strength and static uncture resistance as well as considerable elongation. Materials An analysis of manufacturing technology s influence on the mechanical and hydraulic roerties of nonwoven geotextiles marked out for testing was conducted. It included the designing and roduction of needle unched nonwoven geotexstiles of an intended mass er unit area on the basis of currently used technologies and evaluation of selected mechanical and hydraulic roerties. For metrological and hydraulic tests soft nonwoven geotextiles were selected - the olyroylene nonwoven geotextiles were roduced by the Lentex Public Comany in Lubliniec, manufactured by two different needle unching techniues (Table 1): mechanical needle unching on two sides (both sides) x x 1 x 2 FERER set Fehrer Set geotextiles manufactured by two-sided unching D: x - 15 dtex/50 mm olyroylene fibres y i - mass er unit area geotextiles y 1 - y 5, M = [ ]T g/m2 Z FERER set Fehrer Set geotextiles manufactured by mechanical needle unching in two layers with fabric T: x 1-15 dtex/50 mm olyroylene fibres x 2 - olyroylene fabric 100% y i - mass er unit area geotextiles y 1 - y 4, M = [ ] T g/m 2 Figure 1. Manufacturing geotextiles by mechanical two-sided needle unching and by two-layered needle unching on the fabric underlay (Malkiewicz J. 2009). Z y i y i 94 Malkiewicz J, Drobina R, Lewandowski S. Analysis of the Main Proerties of Geotextiles Manufactured by Mechanical Two-Sided Needle Punching and by Two-Layered Needle Punching on the Fabric Underlay. FIBRES & TEXTILES in Eastern Euroe 2012; 20, 5(94):

2 mechanical needle unching in two layers with fabric In the exeriment olyroylene stale fibres (100% PP) with a linear density of 15 dtex and a stale length of 60 mm were used. A mass er unit area of g/m 2 for mechanical needle unching on two sides and g/m 2 for mechanical needle unching in two layers with fabric was the criterion of geononwoven selection for testing. The mass er unit area of the fabric underlay of lain weave made u of olyroylene taes was eual to 100 g/m 2 for all tyes of geotextiles. The following geotextiles were taken into account: obtained by two-sided needle unching: mass er unit area M = [ ] T g/m2, obtained by mechanical needle unching in two layers with fabric: mass er unit area M = [ ] T g/m2. A lan of exeriment The geotextiles were manufactured by a FERER set according to the manufacturing cycle illustrated in Figure 1. These are the following arts of the cycle: rearing the raw material, nonwoven fibre web forming on an aerodynamic carding machine, imlementation of the base in the form of woven fabric (in the case of geotextile manufactured by two-layered needle unching on the fabric underlay), needle unching of a geononwoven fibre web by means of a mechanical device for needling, cutting off the edges, winding and acking. Methods of investigation The geotextiles were investigated. The scoe and kind of testing of the geotextiles roerties were adjusted to the function which the materials fulfil in the construction. Nonwoven geotextiles are mainly alied as dranage filtration and a searation layer as well as in fabric for reinforcement. The tests concerned hysical, mechanical and hydraulic roerties. All tests were erformed on the basis of harmonised Euroean Standards. The hysical and mechanical roerties of the geotextiles were characterised by the following arameters: mass er unit area (PN-EN ISO 9864), thickness FIBRES & TEXTILES in Eastern Euroe 2012, Vol. 20, No. 5 (94) Table 1. Parameters of manufacturing geononwovens. No. Parameter Geonwovens - two-sided needle unching 1. Raw materials: PP100% PP 15 dtex/60 mm 2. Prearation of raw material: Device for recise defining ercentage of fibres Geonwovens -two-layered needle unching on the fabric underlay 1. PP100% PP 15 dtex/60 mm 2. fabric PP -100 g/m 2 Device for recise defining ercentage of fibres 3 Process of manufacturing FERER set FERER set 4. Seed of needling in m/min K - 3,0 K - 3,0 5. Tye of needles FOSTER F 206/3B FOSTER F 206/3B 6. Deth of needling in mm) Punching density in l/cm Mass er unit area after needling in g/m 2 D/ D/ D/ D/ D/ T/ T/ T/ T/ Width after needling in cm Length of winding in mb Table 2. Statistical arameters of the mechanical roerties of geotextiles manufactured by two-sided needle unching D; Legend: descrition for Tables 2 and 3 mass er unit area, e 2 kpa thickness at ressure 2 kpa, e 20 kpa - thickness at ressure 20 kpa, e 200 kpa - thickness at ressure 200 kpa, F r MD tensile strength in machine direction, F r XMD - tensile strength in cross machine direction, E MD elongation at maximum load in machine direction, E XMD - elongation at maximum load in cross machine direction th, F CBR static uncture,resistance, F D dynamic uncture resistance, statistics: X - mean value, V % coefficient of variation, U mean error, geotextile direction: MD machine direction, XMD cross machine direction, D geotextiles manufactured two sided needle unching, T geotextiles manufactured by two layered needle unching on the fabric underlay. M Parameter, e 2kPa, e 20kPa, e 200kPa, F r MD, F r XMD, E MD, E XMD, F CBR, F D, g/m 2 mm mm mm kn/m kn/m % % kn mm x D/200 V% u x D/300 V% u x D/400 V% u x D/500 V% u x D/600 V% u Table 3. Statistical arameters of the mechanical roerties of geotextiles manufactured by two-layered needle unching on the fabric underlay T. M Parameter, e 2kPa, e 20kPa, e 200kPa, F r MD, F r XMD, E MD, E XMD, F CBR, F D, g/m 2 mm mm mm kn/m kn/m % % kn mm x T/200 V% u x T/400 V% u x T/600 V% u x T/800 V% u

3 Table 4. Results of variance analysis test according to double classification in the case of geotextiles manufactured by twosided needle unching. at a articular ressure - 2, 20, 200 kpa (PN-EN ISO 9863), tensile strength, elongation at a maximum load (PN-EN ISO 10319), static uncture resistance - CBR method (PN-EN ISO 12236), and dynamic uncture resistance - cone dro test (PN-EN ISO 13433). The hydraulic roerties were characterised by the water flow caacity (PN-EN ISO 11058), water ermeability in the lane (PN-EN ISO 12958), and characteristic oening size (PN-EN ISO 12956). Results and discussion According to the research rogramme (Figure 1) and methods of investigation and analysis of exerimental data, the research was conducted in order to determine the influence of the mass er unit area on the basic mechanical and hydraulic arameters of the geotextiles. Statistical arameters of the mechanical roerties for two-sided needle unching and two-layered needle unching are shown in Tables 2 and 3 (see age 95). Analysing the data shown in Tables 2 and 3, it can be assumed that when the mass er unit area increases: 96 - considerable influence has not been roved - considerable influence of the factor Parameter N M analysed F A.α F kr F E.α F kr i=0, i=0, i= i= Tabela 5. Results of the variance analysis test according to double classification for geotextiles manufactured by two-layered needle unching with fabric; - considerable influence has not been roved - considerable influence of the factor Analyzed N M arameter F A.α F kr F E.α F kr i=0, i=0, i= i= The thickness of geotextiles manufactured by two-sided and two-layered needle unching on the fabric underlay at ressures 2, 20 and 200 kpa increases, whereas under the influence of changing ressures the thickness decreases. In the case of geotextiles manufactured by two-sided needle unching, the tensile strength in the machine direction F r MD and in the cross machine direction F r XMD increases, then the static uncture resistance F CBR increases, whereas the dynamic uncture resistance F D decreases. In the case of geotextiles manufactured by two-layered needle unching on the fabric underlay, the tensile strength deends on the fabric, which causes an increase in both directions, with the value of tensile strength being similar for both directions In the case of geotextiles manufactured by two-sided needle unching, the elongation at a maximum load in the machine direction -E rmd and in the cross machine direction E rxmd increases, whereas in the case of geotextiles manufactured by two-layered needle unching on the fabric underlay, the elongation is indeendent of M ; the elongations in the machine and cross machine directions are very little and similar to each other, and the fabric underlay considerably reduces the elongations, which is very essential for reinforcement. Determination of water flow caacity in the lane Determination of the water flow caacity in the lane was erformed for two hydraulic gradients i = 0.1 and i = 1 under a load of [ ]T in kpa for the machine and cross machine directions. A variance analysis test was carried out according to double classification to check the changes occurring. Values of the statistics are resented in Tables 4 and 5. In order to illustrate simultaneous changes in the ressure N and mass er unit area M of the geotextiles for hydraulic gradients i = 0,1 and i = 1 in the machine and cross machine directions, the following form of substitute characteristics was determined: = f N ng ( ) Analysing the data resented in Figure 2, ermeability in the lane of the roduct ng in the machine direction for geotextiles unching, where i = 1, is obtained at low ressures - N and at a mass er unit area amounting to g/m 2. In the range N = 0 55 kpa, the more the ressure increases, the more the water ermeability in the lane of the geotextiles ng decreases; in the range N = kpa the water ermeability does not change, and in the range N = kpa arameter slightly increases. When the mass er unit area of the geotextiles analysed increases, the water ermeability slightly increases to M = g/m 2, does not change in the range M = g/m 2, and slightly decreases in the range - M = g/m 2. As for the use of geotextiles unching, ressures in the range N = 0 20 kpa and mass er unit area M = g/m 2 should be used. In the case of the cross machine direction, ermeability in the lane of the roduct ng of geotextiles manufactured by two-sided needle unching is obtained at ressures in the range of N = 0 20 kpa, regardless of the M value. The more the ressure increases in the range of N = 0 50 kpa, the more the water ermeability decreases; in the range of N = kpa the water ermeability does not change, whereas in the range of N = kpa the water ermeability of the geotextiles slightly increases. Changing the mass er unit area M of the geotextile slightly influences the water ermeability. As for the use of geotextiles unching, ressures N = 0 20 kpa should be used regardless of the mass er unit area M value. Analysing the data resented in Figure 3, ermeability in the lane of the roduct ng in the machine direction of geotextiles manufactured by two-layered needle unching on the fabric underlay, where i = 0,1, is obtained at ressures N = = 0 20 kpa and mass er unit area M = g/m 2. As for use of the geotextiles analysed, these are the most useful value ranges of both the arameters. At ressure N = 80 kpa and at mass er unit area M = 400 g/m 2 the least favourable local minimum of the water ermeability is obtained, whereas the biggest water ermeability in the FIBRES & TEXTILES in Eastern Euroe 2012, Vol. 20, No. 5 (94)

4 Figure 2. Water ermeability regression of geotextiles unching ) R 2 = 0.626; R = 0.791; F calc. = 4.69; F crit, = 2.96, ), here i = 1;, where i = 1; R 2 = 0.737; R = 0.858; F calc. = 7.85; F crit. = Figure 3. Water ermeability regression of geotextiles manufactured by two-layered needle unching on the fabric underlay ), where i = 0.1; R 2 = 0.84; R = 0.910; F calc. = 10.78; F crit. = 3.33, ), where i=0.1; R 2 = 0.74; R=0.86 F calc. = 5.89, F crit. = Figure 4. Water ermeability regression of geotextiles manufactured by two-layered needle unching on the fabric underlay; ), where i = 1; R2 = 0.820; R=0.91; F calc. = 9.68; F crit.. = 3.33, ), where i = 1; R2 = 0.835; R = 0.91; F calc. = 10.38; F crit.. = lane of the roduct ng is obtained at ressures in the range N = 0 20 kpa, regardless of the mass er unit area M. The more the ressure increases in FIBRES & TEXTILES in Eastern Euroe 2012, Vol. 20, No. 5 (94) the range N = 0 50 kpa, the more the water ermeability decreases; in the range N = kpa the water ermeability does not change, whereas in the range N = kpa the water ermeability of the geotextiles slightly increases. Changing the mass er unit area M slightly influences the water 97

5 Table 4. ydraulic arameters of geotextiles obtained by two-sided needle unching. ermeability of the geotextiles. As for the use of these geotextiles, ressures N = 0 20 kpa should be used regardless of the mass er unit area M value. Analysing the data resented in Figure 3, ermeability in the lane of the roduct ng in the cross machine direction of geotextiles manufactured by two-layered needle unching on the fabric underlay, where i = 0.1, is obtained at ressures N = 0 20 kpa, regardless of the M value. When the ressure increases, the water ermeability decreases in the range N = 0-50 kpa, does not change in the range N = kpa and slightly increases in the range kpa. The influence of the mass er unit area on water ermeability is very little. As for use of the geotextiles, ressures of N = = 0-20 kpa should be used regardless of the M value. Analysing the data resented in Figure 4 (see age 97), it can be assumed that the biggest water ermeability in the lane of the roduct ng in the machine direction of geotextiles manufactured by two-layered needle unching on the fabric underlay, where i = 1, is obtained at ressure N = 0 20 kpa regardless of the mass er unit area M value. As for use of the geotextiles analysed, this is the most useful range of the value of both the arameters. At ressure N = 75 kpa and mass er unit area M = 500 g/m 2 the least favourable local minimum is obtained, whereas the biggest water ermeability in the lane of the roduct ng is obtained at ressure N = 0 20 kpa and mass er unit area in the range M = g/m 2. These are the most useful ranges of the value of both the arameters. The more the ressure N increases, regardless 98 Parameter D/200 D/300 D/400 D/500 D/600 Water ermeability characteristics normal to the lane, without load VI 50, m/s Characteristic oening size 0 90, mm Table 5. ydraulic arameters of geotextiles obtained by two layered needle unching on the fabric underlay. Parametr T/200 T/400 T/600 T/800 Water ermeability characteristics normal to the lane, without load VI 50, m/s Characteristic oening size 0 90, mm of the mass er unit area of the geotextile analysed M, the water ermeability of the geotextile decreases in the range N = 0 40 kpa, and in the range N = = kpa arameter ng does not change. The biggest water ermeability in the lane of the roduct n in the cross machine direction of geotextiles manufactured by two-layered needle unching on the fabric underlay, where i = 1, is obtained at ressure N = 0 20 kpa and mass er unit area M = g/m2. These are the most useful value ranges for both arameters. When the ressure increases, the water ermeability decreases in the range N = 0-40 kpa and does not change in the range N = kpa, regardless of the mass er unit area value. Determination of water ermeability characteristics normal to the lane without a load and determination of the characteristic oening size Determination of water ermeability characteristics normal to the lane without a load and determination of the characteristic oening size 0 90 were conducted in order to check the influence of the mass er unit area on filtration roerties. The results of the investigation are resented in Tables 4 and 5. Analysing the data from Tables 4 and 5, it can be assumed that the increase in the mass er unit area is accomanied by a decrease in water ermeability normal to the lane for both geotextiles, whereas a rise in the mass er unit area is accomanied by a fall in the characteristic oening size for both geotextiles, which directly imacts the filtration and drainage functions. igher values of these arameters were obtained for geotextiles manufactured by two sided needle unching. Conclusions According to the investigation conducted and analysis of measurement results, it can be assumed that: 1. Geotextiles manufactured by twosided needle unching have very good hydraulic roerties thanks to their satial structure. The limited level of tensile strength, static and dynamic uncture resistance as well as significant elongations are their disadvantages. 2. Geotextiles manufactured by twolayered needle unching on the fabric underlay, aart from good hydraulic roerties, have very good mechanical roerties thanks to the fabric underlay. 3. Geotextiles obtained by mechanical needle unching can be successfully alied to drainage and filtration, whereas geotextiles manufactured by two-layered needle unching on the fabric underlay are articularly useful for reinforcement mainly in civil engineering, in which, aart from drainage and filtration functions, reinforcement is essential. References 1. Malkiewicz J. Geotextile nowoven comosites as the innovative underlayers in geogrids and geogabions. Doctoral dissertation, University of Bielsko-Biała, Poland, Malkiewicz J, Bartkowiak E. Influence of mechanical needle unching on chosen roerties of nonwowen geotextiles. Inżynieria Morska i Geotechnika 2010; 5: Mashroteh, Zarrebini M. Analysis of unching force during random-velour needling. Text. Res. J. 2011; 81, 3: Miao M, Glassey, E. An Exerimental Study of the Needled Nonwoven Process: Part I: Fiber Geometry Before Needle Punching. Text. Res. J. 2004; 74, (4): Watanabe A, Miwa M, Yokoi T, Merati A, A. Predicting the Penetrating Force and Number of Fibers Caught by a Needle Barb in Needle Punching. Text. Res. J. 2004; 74, (5): Koias K, Mikołajczyk Z, Kowalski K. Knitted Geotextiles for Road Reinforcement. Fibres & Textiles Eastern Euroe 2011; 19, 6(89): Ghane M, Saghafi R, Zarrebini M, Dariush S. Evaluation of Bending Modulus of Needle-Punched Fabrics Using Two Simly Suorted Beam Method Mohammad Fibres & Textiles Eastern Euroe 2011; 19, 4(87): Received Reviewed FIBRES & TEXTILES in Eastern Euroe 2012, Vol. 20, No. 5 (94)