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  • Pavement Engineering

    and Materials

    Flexible Pavements

    CSIR-CRRI, New Delhi

    19

  • Pavement Engineering

    and Materials

    Flexible Pavements

    CSIR-CRRI, New Delhi

    21

    Development of Composite from Fly Ash and Plastic Waste for Bituminous Road Construction

    The objective of this study is to develop a composite by blending fly ash and plastic waste for its use as filler in bituminous road construction. Stone Matrix Asphalt (SMA) requires 8 to 10 per cent filler and offers improved functional as well as structural characteristics over traditional bituminous concrete mixes. In the present study, the laboratory performance characteristics of SMA mixture containing fly ash and composite have been investigated by various laboratory tests such as indirect tensile strength, indirect tensile strength ratio, static creep at different temperatures, resilient modulus at different temperatures and rutting resistance by wheel tracking test. Laboratory tests indicate increased resistance to moisture sensitivity of SMA mixture containing composite as filler. The values of resilient modulus of the SMA mixture containing composite are fairly high compared to SMA mixture with plain fly ash as filler indicating potential of such SMA mixes for better pavement performance. The rutting in SMA mixture containing composite is reduced to 1.75 mm as compared to 2.3 mm in SMA with plain fly ash. The values of creep modulus of SMA mixture containing composite are higher compared to mixture of plain fly ash filler. The results of mechanistic analysis indicate significant increase in allowable number of traffic on use of composite as filler in SMA mixture. These findings indicate that SMA containing composite is an acceptable material for bituminous road construction.

    Results of rut depth studies and resilient modulus studies are shown in Figs. 20 and 21.

    Fig. 20 Rut depth versus no. of cycles of SMA mixtures

    D e v e l o p m e n t o f P o l y m e r Modified Binder with Improve Compatibility

    The world is facing a waste disposal crisis from the most problematic plastic produced today i.e. Poly Vinyl Chloride (PVC). The products made up of PVC are reported to be causes of dioxin pollution during incinerations. In this study, PVC pipe waste has been used as a modifier up to a level of 3 per cent and 5 per cent to made bituminous products for paving applications. PVC is not compatible with bitumen, therefore to make homogeneous blend of PVC with bitumen, waste PVC was

    Fig. 21 Resilient modulus of SMA mixtures at different temperatures

  • Annual Report 2011-12

    22

    Pavement Engineering

    and Materials

    Flexible Pavements

    treated with a chemical followed by blending with bitumen. The visco-elastic property of the bitumen-PVC blends such as storage modulus, loss modulus and phase angle were determined and compared with values of unmodified bitumen. The performance characteristics of bituminous mixes made up of these PVC modified binders were also investigated and compared with those of conventional bituminous mixes. The results indicate that PVC pipe waste can be used in bituminous road construction. Strength and stability of the mixes increase by the incorporation of PVC pipe waste. It was also observed that addition of PVC pipe waste in bitumen showed increased resistance to permanent deformation.

    Development of Technology to Produce and Lay Down the Modi ed Bituminous Mixtures at Lower Temperatures

    Warm Mix Asphalt (WMA) mixes are produced at lower temperature, while maintaining key advantage of hot mixes. The aim of the present study is to investigate mechanistic properties of polymer modified warm mix asphalt (PMWMA) for reduction of mixing, laying and rolling temperature. The optimum dose of additive for reduction of operational temperatures is determined by viscosity-temperature relationship and performance properties of PMWMA. Laboratory performance properties of traditional PMB mix and PMWMA such as Marshall stability, retained stability, indirect tensile strength ratio, Marshall quotient, ITS, creep and resilient modulus at different

    temperatures, fatigue life and rutting are investigated. Results reveal that optimum dose of organic surfactant additive (warm mix) lies in the range of 1.5 to 2.0 per cent by weight of PMB to achieve lower mixing, laying and rolling temperature. The reduction in temperatures by a factor of 30 to 40°C is achieved. Values of creep modulus and resilient modulus of PMWMA are found superior at different temperatures, indicating better performance. Rutting is also found lower compared to traditional PMB mix. Fatigue life of PMWMA mixes determined by 4 point bending beam fatigue test is observed higher than conventional PMB mix. The better indirect tensile strength ratio values indicate potential of PMWMA towards prevention of moisture damage even after compaction at lower temperature. Improved performance of PMWMA alleviate compaction problem of traditional hot PMB mixes at lower temperature. The clean and safe environment due to reduction in production temperature besides better road performance under heavy traffic and extreme climatic condition is expected to enhance the use of warm PMB mixes in bituminous road construction in place of traditional PMB mixes.

    Effect of Higher Axle Weight and Moduli Variation of Pavement Materials on Fatigue and Rutting Life of Flexible Pavement

    To find out the impact of increased axle weight and moduli variation on fatigue and rutting life of bituminous pavement, an in-house study is under progress. Resilient modulus of bituminous mix at different temperature

  • Pavement Engineering

    and Materials

    Flexible Pavements

    CSIR-CRRI, New Delhi

    23

    has been determined to carry out further mechanistic analysis.

    Performance Evaluation of Test Section Laid with Stone Matrix Asphalt (SMA) Surfacing in NDMC Area

    The performance of SMA test section laid at Zakir Husain Road in NDMC area was done. The data of deflection by Benkelman beam, roughness and distress have been collected for final observation. The surface of test section is observed satisfactory.

    Mechanistic Evaluation of Warm Asphalt Mixture Containing Crumb Rubber Modi ed Bitumen

    Crumb Rubber Modified Bitumen (CRMB) is a popular binder in India due to its better performance compared to traditional paving grade bitumens. The drawbacks of these high energy CRMB mixes over traditional bituminous mixes are requirement of higher mixing, laying and rolling temperatures. New moderated temperature mixing technologies are graining attention due to stricter environmental restrictions. Warm Mix Asphalt (WAM) technology, reduces the production and application temperatures of bituminous mixes during construction. Therefore, an attempt is made in this study to develop a method to reduce mixing and compaction temperature of CRMB mixes for safer working, retention of improved properties, save fuel and reduce green house gas emissions in road construction. The optimum dose of additive for reduction of

    operational temperatures is determined based on viscosity-temperature relationship of CRMB and additive blends as well as mechanistic properties of modified CRMB mixes. The laboratory performance of warm asphalt mixture containing CRMB is found comparable or superior to traditional CRMB mixes in terms of Indirect Tensile Strength (ITS), ITS ratio, resilient modulus, deformation, rutting and fatigue. Results reveal that optimum dose of organic surfactant additive is found 2.0 per cent by weight of crumb rubber modified bitumen to lower mixing, laying and rolling temperatures by 30°C to reduce requirement of fuel.

    D e v e l o p m e n t o f S u i t a b l e Methodology in terms of Repair Treatment of Defence Runway in Emergency

    Damages caused due to bombing by enemy’s air actions develop in the form of craters which are of different magnitude in terms of shape and dimensions. It is absolutely essential to continue to operate airfield pavements damaged by air bombing and by other similar weapons. Therefore, the repair essentially must be completed immediately and rapidly after the attack so as to allow the launching and recovery of combat aircrafts. New developments in the weapon technology with deep strikes and increased demands in aircraft operations make existing crater repair procedures complex, inadequate and unsuitable. The cold mixes of bituminous concrete have been developed for better load dissipation. The results are given in Table 4.

  • Annual Report 2011-12

    24

    Pavement Engineering

    and Materials

    Flexible Pavements

    Study on Validation of IRC Pavement Design Method Using Heavy Vehicle Simulator (HVS)

    After the successful completion of stipulated ‘Site Acceptance Test (SAT)’ of APTF, an in- house project entitled ‘Study on Validation of IRC Pavement Design Method Using Heavy Vehicle Simulator (HVS-APTF)’ was initiated. The main objective of the study includes :

    Construction of a Test Strip within CRRI with specifications conforming to MoRT&H

    Verify the ‘Design Life’ as envisaged

    Attempt to validate IRC design method

    The pavement structure and associated instrumentation involved in this study are shown in Figs. 22 and 23.

    Evaluation of Jute Geo-textile for Retardation of Re ection Cracking in Bituminous Pavements

    This project has been sponsored b

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