Gill geoshanghai-2010 2003
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Gill geoshanghai-2010 2003

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    Gill geoshanghai-2010 2003 Gill geoshanghai-2010 2003 Presentation Transcript

    • A.K.Choudhary 1 , J.N.Jha 2 , K.S.Gill 3   1 Deptt. of Civil Engg., NIT, Jamshedpur, India 2,3 Deptt. of Civil Engg., GNDEC, Ludhiana, India PRESENTED BY: K.S.GILL [email_address]
      • Thickness of flexible pavement depends upon subgrade strength and traffic intensity.
      • Soil reinforcement is an effective and reliable technique to improve the strength of soil subgrade.
      • Geotextiles and geogrids are commonly used in engineering practices.
      • Waste plastic can be a cheaper alternative of costly georids/geotextiles for construction of low cost roads.
      • Solid waste production in India: 39 million tons /year (2000)
      • Expected production by 2010: 56 million tons /year
      • Typical %age of plastic in Municipal solid waste : 1% (India)
      • Best way to handle such waste :Utilization in engineering application
      • Application in Soil reinforcement : If found effective can be a significant secondary market for waste plastic
      • Possibility of replacing costly reinforcing material like geogrid
      • Effect of mixing different %age of high density poly ethelene (HDPE) strips on CBR value of subgrade soil .
      • Environment friendly disposal of non-biodegradable municipal waste.
      • To contribute towards the sustainable development of road infrastructure.
      • To reduce the construction cost.
      • SAND: Locally available sand(Jamshedpur,Jharkhand) (India)
      • Specific gravity: 2.62,
      • D 50 : 0.55 mm,
      • C u : 2.40, C c : 1.67
      • Classification: ‘SP’,
      • γ max : 16.5kN/m 3
      • γ min : 14.6kN/m 3
      • HDPE:
      • Purchased from a rag picker, at a price of INR 100 per kg (approximately $2per kg).
      • Width of HDPE : 12mm and Thickness: 0.40mm.
      • Length of HDPE : 12mm [Aspect Ratio (AR=length/width) =1],
      • (Selected) 24mm (AR=2)
      • 36mm (AR=3)
      • Ratio of mould diameter to maximum strip length ≥ 4
      • (Ensures sufficient space for strip to deform freely and remains independent of mould confinement)
      • Ultimate tensile strength of this strip: 0.36kN
      • and percent elongation at failure: 23% (ASTM D 4885)
      • Strip content (Defined in present case): Ratio of weight of strips to the weight of dry sand.
      • Strip content selected for the tests: 0.0%, 0.25%, 0.50%, 1.0%, 2.0% and 4.0%.
      • Preparation of specimens:
      • CBR mould of 150 mm diameter and 175 mm high
      • Density and relative density of compacted sand: 16.2kN/m 3 D r = 85%
      • No. of layers: Three
      • Density of HDPE strip reinforced sand layers kept equal to dry density of that of unreinforced sand.
      • Required amount of HDPE strips were randomly mixed with dry sand.
      • Mix transferred to the mould and a surcharge (base plate 148 mm in diameter) weighing 25 N placed over the sample (to avoid segregation of the strips during vibration).
      • Compaction of specimen: vibration for 2 minutes on a vibration table.
      • Tests performed: As per procedures described in IS-2720-Part XVI-1987
      • A surcharge plate of 2.44kPa placed on the specimen prior to testing.
      • Loads recorded as a function of penetration (up to a total penetration of 12.5 mm).
      • CBR and Secant modulus determined from Load vs Penetration curve
      • CBR values reported in the present investigation are those of 5.0 mm penetration (CBR value at 5.0 mm penetration observed higher than that of 2.5 mm penetration even on repetition).
      • Increase in CBR value due to the presence of HDPE strip content: Expressed by California Bearing ratio Index (CBRI)
      • CBRI = CBR r /CBR u
      • CBR r : California bearing ratio (CBR) value of reinforced soil
      • CBR r : California bearing ratio (CBR) value of unreinforced soil
      • Secant modulus: Defined as the ratio of load in kPa at a penetration of 5.0 mm to the penetration of 0.005m
      • (obtained from load penetration curve)
      • Variation of load-penetration curves (AR=1) with different strip content (0.025% to 4.0%)
      • Variation of load-penetration curves (AR=2) with different strip content (0.025% to 4.0%)
      • Variation of load-penetration curves (AR=3) with different strip content (0.025% to 4.0%)
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      • After completion of each test: Specimens were dissected and strip examined
      • Many of the strips showed elongation, thinning and clear impression of sand particles
      • As soil sheared during penetration, strip fixed in the sand by friction elongated as the soil deformed
      • CBR value of HDPE strip reinforced sand at 5.0mm penetration were found to be higher than those at 2.5 mm penetration
      • At higher deformation HDPE strip reinforcement is more effective in improving the strength of sand by increasing the resistance to penetration
      • Situation (a) plunger pushes down particle ‘C’ to occupy position in between particle ‘A’ and ‘B’
      • The strips resist the downward movement of particle ‘C’ until slippage between soil and strip occur resulting into a development of situation (b)
      • Interaction between soil and strips causes the resistance to penetration of the plunger resulting into higher CBR values
      • The addition of reclaimed HDPE strips a waste material to local sand resulted in an appreciable increase in the CBR and the secant modulus
      • The reinforcement benefit increases with an increase in strip content and the aspect ratio and maximum improvement in CBR and secant modulus of a reinforced system is around three times to that of an unreinforced system.
      • Though the maximum improvement in CBR and secant modulus is obtained when the strip content is 4% and the aspect ratio 3, but even at 2% strip content the improvement in CBR is also appreciable.
      • Small size of CBR mould limits size & amount of fibre inclusion
      • End effects in small sample size is more pronounced
      • Despite these limitations large experience base and satisfactory design method are in use based on CBR test results
      • Further study needed (a) to optimise the size, shape of strips
      • (b) to assess the durability and aging of strips
    •