TESTING GEOGRIDS. Test Procedure for. TxDOT Designation: Tex-621-J 1. SCOPE 2. DEFINITION 3. SAMPLING 4. DETERMINING APERTURE SIZE

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1 est Procedure for xdo Desigatio: ex-621- Effective Date: August SCOPE 1.1 Use this method to sample ad test geogrid materials used i costructio. 1.2 Characteristics Covered aperture size percet ope area thickess flexural rigidity tesile stregth ad modulus juctio stregth ad efficiecy. 1.3 he values give i paretheses (if provided) are ot stadard ad may ot be exact mathematical coversios. Use each system of uits separately. Combiig values from the two systems may result i ocoformace with the stadard. 2. DEFINIION 2.1 Geogrid a sythetic plaar structure formed by a regular etwork of tesile members with appropriate apertures to allow iterlockig with surroudig soil or aggregate for the purpose of reiforcemet ad/or segregatio. 3. SAMPLING 3.1 Uless otherwise specified, sample geogrid i accordace with ex-735-i. 4. DEERMINING APERURE SIZE 4.1 Measure the maximum iside dimesio of the aperture i each pricipal directio. 4.2 Radomly take 5 measuremets from apertures i each directio by meas of verier calipers. 4.3 Measure accurately to 0.01 mm ( i.) CONSRUCION DIVISION 1 6 LAS REVIEWED: OCOBER 2014

2 5. DEERMINING PERCEN OPEN AREA 5.1 Cut a represetative mm (8 10-i.) specime from the geogrid sample, maitaiig a cotiuous patter of the aperture. 5.2 race the grid patter, usig light projectio, oto a piece of paper. 5.3 Weigh grid patter (paper) ad record total weight. 5.4 Cut out the aperture areas from the grid patter o the paper, separate them from geogrid area ad weigh the cutouts. 5.5 Record readigs to the earest g. 5.6 Determie the percet ope area by dividig the weight of the cutouts by the weight of the paper ad multiply by DEERMINING HICKNESS 6.1 Determie the thickess of s ad juctios with verier calipers by takig the average of 5 readigs selected radomly at differet locatios of the grid. 6.2 Follow ASM D DEERMINING FLEXURAL RIGIDIY 7.1 Follow ASM D 1388, Optio A, except that the width of the specimes will be 3 s, with the cuts made at the midpoits betwee the s. 8. DEERMINING ENSILE SRENGH AND MODULUS 8.1 Apparatus: esile testig machie, capable of testig with a costat rate of extesio (50 mm/mi. [2 i./mi.]), ad measurig the tesile force, typically with a load cell havig the capacity to test the full rage of samples. It must be able to display ad record the etire force versus elogatio curve durig the test estig clamps, with mm (1 2-i.) serrated jaws ad appropriate clampig power to prevet slippig or crushig. 8.2 Preparig est Specimes: est specimes must cotai oe with 3 juctios i the directio of cocer Use juctios at each ed of the specime for clampig; the ceter ode represets the repeat uit. CONSRUCION DIVISION 2 6 LAS REVIEWED: OCOBER 2014

3 8.2.3 est 5 specimes i each directio (md ad cmd). 8.3 Procedure: Balace ad calibrate the test system Determie the gauge legth, to the earest 0.01 mm ( i.), by measurig from the ceter poit of the ed juctios Mout the specime i the clamps, usig the juctios at each ed, i lie with the directio of pull ighte the grips sufficietly to prevet slippage of the sample durig the test, but ot to the poit where damage would occur to the specime Use the iitial gauge legth of the sample to determie the modulus at a specified elogatio est the sample usig a crosshead speed of 51 mm (2 i.) per miute. Note 1 Uless otherwise specified, determie the modulus at 2% elogatio, based o the gauge legth as measured above Calculate the average maximum tesile stregth ad average geogrid tesile stregth as desced uder Sectio Calculatios: Calculate average maximum tesile stregth: i l i average maximum tesile stregth, N i maximum tesile stregth of i th specime, N total umber of test specimes (5). CONSRUCION DIVISION 3 6 LAS REVIEWED: OCOBER 2014

4 8.4.2 Calculate average geogrid tesile stregth: grid ( )( ) grid average geogrid tesile stregth, N/m umber of s per meter Calculate average secat modulus at 2% strai: M 2 % i l 2% ( 0.02 ) M 2% Average secat modulus at 2% strai, N otal umber of test specimes (5) 2% esile stregth of the i th specime at 2% elogatio Report the average geogrid tesile stregth to the earest Newto/meter ad the average secat modulus at 2% modulus to the earest Newto. 9. DEERMINING UNCION SRENGH 9.1 Apparatus: esile testig machie, capable of testig with a costat rate of extesio ad of measurig the tesile force, typically with a load cell havig the load capacity to test the full rage of samples. It must be able to display ad/or record the complete forceelogatio curve durig the test uctio clamps, able to provide the appropriate clampig power to prevet slippig or crushig Rib clamps, with mm (2 1-i.) serrated jaws to secure the portio of the specime without slippig or crushig. 9.2 Preparig est Specimes: Prepare the specimes i the shape of a by cuttig juctios from each directio. CONSRUCION DIVISION 4 6 LAS REVIEWED: OCOBER 2014

5 9.2.2 Cut the specimes to allow for the maximum amout of trasverse o each side of the juctio to be tested he ceter must be log eough a miimum of 3 odes to allow clampig actio withi the clamp est 5 specimes i the directio of cocer. 9.3 Procedure: Balace ad calibrate the tesile machie Istall testig clamps. Note 2 he juctio clamp is the upper fixture, ad the clamp is the lower fixture Mout specime so that the clamp attaches to the ceter of the ad the juctio clamp attaches o both sides to the trasverse. he juctio clamp should grip the specime as close to the juctio as possible without actually cotactig it Load the specime at a rate of 51 mm (2 i.) per miute util rupture occurs Determie juctio stregth as desced uder Sectio Calculatios: Calculate average maximum juctio tesile stregth: i l i average maximum juctio tesile stregth, N i maximum juctio tesile stregth of i th specime, N otal umber of test specimes (5) Calculate average geogrid juctio stregth i the directio of cocer: grid ( )( juctio ) grid average geogrid juctio stregth, N/m juctio umber of juctios per meter. CONSRUCION DIVISION 5 6 LAS REVIEWED: OCOBER 2014

6 9.4.3 Calculate juctio efficiecy stregth: E juctio x100 E juctio juctio stregth efficiecy average maximum juctio tesile stregth, N average maximum tesile stregth, N Report the average maximum juctio tesile stregth ( ) to the earest Newto, average geogrid juctio stregth ( grid ) to the earest Newto/meter, ad juctio stregth efficiecy (E juctio ) to the earest whole percet. CONSRUCION DIVISION 6 6 LAS REVIEWED: OCOBER 2014