30 AUGUST 2009 229 - ??(-15 dB height) was obtained when ... prilling towers, chimneys, furnaces,...

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Transcript of 30 AUGUST 2009 229 - ??(-15 dB height) was obtained when ... prilling towers, chimneys, furnaces,...

  • 30 AUGUST 2009 229229229229229

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    Fig. 3: Visible spectrum generated from the PCF through femtosecond pulse pumping

    A 28 cm long piece of PCF wasbroken off from the main 20 m longfiber, cleaved and tested. The Fig-ure 4 shows the spectra collected fora range of pulse energies. Each

    R&D Highlights on Building Materials at CBRI, Roorkee

    Development of New Composite Materials for Building ApplicationsUsing Plywood-Veneer and Vermiculite Waste

    The charm of synthetic polymers and their productsused in diverse applications is fading because theseproducts are not biodegradable and they pollute theenvironment. In contrast, natural polymers aregenerally biodegradable but they do not possessdesirable thermal and mechanical properties.Mechanical properties of the developed compositeshould be comparable with the properties ofcomposites with synthetic resins and it must becapable of being processed by the established methods.

    The starting raw material i.e. wood waste fromveneer and plywood industries (Figure 1) is selectedbecause its present price is very low (Rs 1.25 per kgcontaining higher lignin content up to 35% by wt.)while its availability is very large. The generated waste

    Fig.1: Plywood - Veneer Waste

    spectrum was corrected and thennormalized (max point set to 0 dB).For ease of viewing the spectra, thefigures were offset by multiples of5 dB. Using this fiber length, con-

    tinuum spanning from 491-2060 nm(-15 dB height) was obtained whenpumped with 800 nJ pulses.

    Fig. 4: Continuum spectra for 800, 400, 200 and110 nJ incident pulse energy

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    is around 10% of the total woodprocessed in the plants. The otherproposed starting material isbagasse whose availability is alsovery substantial. Its cost is aroundRs 1.00 per kg while lignin contentis substantially low (up to 25% bywt.) and the fibre strength is alsocomparably low. Efforts will bemade to convert lignin of woodwaste of plywood/ veneer industriesinto an adhesive for makingcomposites of a new class ofcomposites replacing syntheticresins mostly derived frompetroleum.

    The exfoliation of vermiculitegenerates powdered by-product(waste shown in Figure 2), which isseldomly used for converting into avalue added product for buildingapplications. This by-product can beeasily converted into roofing tiles for

    Fig. 2: Different Exfoliated Vermiculite Flake Wastes

    thermal insulation along withpolymer modified cementitiousbinder. Substantial amount ofexfoliated vermiculite is available(around 400 MT/year) in India.Exploratory experiments havealready strengthened the objectiveand lead to conceive a project for

    the development of roofing tile forthermal insulation (a composite).

    The envisaged impact of theoutcome of the R&D work is toprovide better alternative buildingmaterials using low value downstream products of agro-industriesthrough value addition.

    Development of Polymer-based High Performance Repair Materials

    The polymeric mortars haveemerged as an important class ofrepair materials in civil engineeringapplications. Polymers are known todegrade at elevated temperaturesbut cement does not loose strengthbelow 100C. Higher temperatureconditions prevail in severalindustrial buildings and structuressuch as coke handling plants,thermal power plants, prillingtowers, chimneys, furnaces, heattreatment plants etc. This study isdevoted to understand the influenceof temperature and chemicals on theperformance of polymeric modifiedmortars and to formulate suitablecomposition for such higher Fig. 3: Polymer modified Repair Material under Test

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    temperature exposure conditions.Figure shows the bond testing of onetypical formulation of repairmaterial under slant shear test inUTM (Figure 3).

    Studies are being carried out onthe developed repair materials toassess the effect of thermal cycles,fire, acidic environment on themortar samples. Influence ofthermal cycles on bondcharacteristics is studied by using

    Fig. 4: Effect of number of thermal cycles oncompressive strength of repair mortars

    Fig. 5: Testing of repair mortars at higher temperature (a) Thermostaticchamber (b) Compression test specimen inside the thermostatic chamber

    Fig. 6: Change in compressive strength of repair mortars tested at highertemperature (85C) in comparison to those tested at RT

    Fig. 7: Change in compressive strength and weight ofrepair mortars after 180 days exposure to acidic solution

    slant shear test specimens and onflexural behaviour for 60 and 120cycles. To understand the influenceof exposure to acidic environment,the specimens were submerged ina sulphuric acid solution (5%) andthe changes in weight, shape, colourand compressive strength arerecorded at various intervals ofexposure time. The effect of thermalcycles on compressive strength ofvarious repair mortars is shown in

    Fig. 4. The results of change incompressive strength of the repairmortar specimens tested at 852 C(Fig. 5) in comparison to those testedat RT are shown in Fig. 6. Thechanges in properties of differentmortar specimens dipped in anacidic solution for 180 days is shownin Fig. 7. Studies regarding firebehaviour of the above mentionedmortars is in progress.

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    Development of Coating Systems for Fertilizer Industries Based on Modified Epoxy

    The demand for coatings for theprotection of structures exposed tochemicals and higher temperatureis huge. The coatings in the fertilizerplants, chemical industries, powerplants etc. especially in thechimneys, prilling towers, etc. areexposed to higher temperatures in

    the range of 50-70C and verylimited coatings are commerciallyavailable for protecting thestructures. The coatings based onmodified epoxy resin, developed,earlier in the institute, showed verygood performance when exposed toa variety of exposure environments.

    This has been undertaken as thebasic starting material fordeveloping a new class of coatingwhich would be useful for protectingthe steel and concrete structures.Fig. 8 shows the coated panels withdeveloped formulations under test.

    Fig. 8: Coated panels with developed formulations under test

    Strategic Work for Health Monitoring and Preventive Measuresfor Deteriorated Concrete Structures in Thermal Power Plants

    Concrete structures in theexisting thermal power plantsdeteriorate at an alarming rate. Theperformances of the structures areaffected by various factors such astemperature, humidity, water andairborne pollutants, and mechanicaldamages. In coal based powerplants the burning of coal producesa very corrosive atmosphere. Theexposure conditions vary fromacidic to very alkaline. Materialslike cement, fibres, latexes, alkyds,epoxies, urethanes, and others areused in a suitable combination,depending on the type of power

    plant and the specific location andexposure to prevent them fromfurther deterioration. The repairand maintenance of different typesof structures require materials andprotective coatings havingsubstantial resistance to thedetrimental elements.

    Presently the installed capacityof power generating units in Indiais about 145,588 MW, out of whichthe share of thermal power is around66.6%. Coal-based thermal powerplants alone are sharing around 80%of this thermal power generation inthe country. Out of it the

    contribution of the thermal powergenerating units is 66.6 %. Furthercapacity addition of 78,000 MW isplanned in the Eleventh Plan, inwhich coal based thermal powercapacity will be 52905 MW (NTPC,2007). Presently, there are about 120coal based thermal power plants inIndia. With further addition of newpower plants the maintenance of theinfrastructures will be a huge taskin future.

    Organic Building MaterialsDivision (OBM Division) isassociated with number of projectson health assessment and repair of

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    thermal power plantstructures throughoutthe country e.g. NTPC,Badapur; Kanti BijleeUtpadan Nigam Ltd.,Muzzaffarpur; NTPC,Thalchar, Orissa;NTPC, Simadri,Visakhapatnam etc. Insuch assignmentspreventive measuresand repairs aresuggested after carryingout rigorous non-destructive testing(NDT) of differentdeteriorated structures.This knowledge ofproject works has greateconomic impact as thecost of the replacementsor construction of suchstructures need a hugeamount of wealth.Besides these, theinstitute has developedvarious patchingmaterials, reinforcementcoatings and groutingmaterials, repair mortarand coatings for steeland concrete structuresover the years and areunder comme