06092013153225-use-of-flyash-in-concrete 1 topic

Information about 06092013153225-use-of-flyash-in-concrete 1 topic

Published on July 29, 2014

Author: piyush114568

Source: authorstream.com


PowerPoint Presentation: 1 FLY ASH FINELY DIVIDED RESIDUE RESULTING FROM COMBUSTION OF POWDERED COAL AN ARTIFICIAL POZZOLAN COMMON INGREDIANT IN CONCRETE FIRST USED IN CONSTRUCTION OF HUNGRY HORSE DAM IN USA IN INDIA, FIRST USED IN RIHAD DAM HIGH VOLUME FLY ASH IS OF CURRENT INTEREST QUALITY OF FLY ASH IS GOVERNED BY IS:3812-1981 PowerPoint Presentation: 2 WHY CHARACTERISTICS? NOT A SPECIALLY MANUFACTURED PRODUCT GOVERNED BY STRICT RULES VARIATION IN CARBON, PARTICLE SHAPE AND SIZE DISTRIBUTION, PRESENCE OF MINERALS, ETC. EXHIBITS DIFFERENT CHARACTERISTICS WITH DIFFERENT COMPOUNDS NO PROPER PROCEESING IS AVAILABLE CHANGE IN THE BEHAVIOUR OF CONCRETE PowerPoint Presentation: 3 TYPES OF FLY ASH(ASTM C 618) CLASS F ANTHRACITE OR BITUMINOUS COAL HAS <5% CaO POZZOLANIC PROPERTIES ONLY CLASS C LIGNITE OR SUB BITUMINOUS COAL HAS >10%CaO POZZOLOANIC & CEMENTATIOUS PROPERTIES PowerPoint Presentation: 4 Sl no Characteristic Requirement 1 Fineness- specific surface in m 2 /kg by Blaine’s permeability method, Min 320 2 Lime reactivity- Average compressive strength in N/mm 2 , Min 4.0 3 Compressive strength at 28 days N/mm 2 , Min Not less than 80% of the strength of corresponding plain cement mortar cubes 4 Dry shrinkage, %, Max 0.15 5 Soundness by autoclave test expansion of specimen, %, Max 0.8 Physical requirements as per IS: 3812-1981 : PowerPoint Presentation: 5 Characteristic by mass Requirement SiO 2 + Al 2 O 3 + Fe 2 O 3 , Min 70.0 SiO 2 , Min 35.0 MgO, Max 5.0 SO 3 , Max 2.75 Na 2 O Max 1.5 Loss on ignition, Max 12.0 Chemical requirements as per IS: 3812-1981: PowerPoint Presentation: 6 Magnified view of the fly ash Microscopic photographs of fly ash (left) and Portland cement (right): PowerPoint Presentation: 7 EFFECT OF FLY ASH ON FRESH CONCRETE WORKABILITY MOISTURE CONTENT TIME OF SETTING BLEEDING PUMPABILITY HYDRATION REACTIONS PowerPoint Presentation: 8 WORKABILITY INCREASED DUE TO HIGHER FINENESS AND SPHERICAL SHAPE OF FLY ASH PARTICLES IMPROVED PLASTICITY AND COHESIVENESS PowerPoint Presentation: 9 MOISTURE CONTENT MAX ALLOWABLE MOISTURE CONTENT IS 3% (ASTM C618) LESS WATER IS REQUIRED WHEN FLY ASH IS USED HIGHER FINENESS OF FLY ASH CREATES GOOD SURFACE FINISH AND EVAPORATION IS REDUCED TIME OF SETTING ALL CLASS F AND MOST CLASS C FLY ASH INCREASE SETTING TIME PowerPoint Presentation: 10 BLEEDING REDUCED GREATER FINES AND LOWER WATER CONTENT PUMPABILITY INCREASED LUBRICATING EFFECT OF SPHERICAL FLY ASH PARTICLES IT HELPS IN PUMPING LONGER DISTANCES PowerPoint Presentation: 11 HYDRATION REACTIONS THE HYDRATION REACTION DOESNOT START OFF IMMEDIATELY AS IN CASE OF NORMAL CONCRETE CLASS F FLY ASH DOESNOT HAVE SELF CEMENTATIOUS PROPERTIES SHOULD MIX WITH Ca(OH) 2 AND ALKALIS WHERE Ca(OH) 2 IS FIXED BY SILICA AND ALUMINA IN FLY ASH CLASS C FLY ASH WHICH HAS MORE LIME CONTENT AND REACTS DIRECTLY WITH WATER AND REACTION IS FASTER COMPARED TO CLASS F FLY ASH PowerPoint Presentation: 12 HEAT OF HYDRATION REDUCED DUE TO LESSER CEMENT CONTENT CANMET (Canada centre for mineral and energy technology) REPORTS THAT HEAT OF HYDRATION WAS LESS BY 15-25 º C OF CONVENTIONAL CONCRETE BLOCK SIZE 3.05X3.05X3.05 METERS MAX TEMP REACHED WAS 54 º C WITH ASTM TYPE I CEMENT MAX TEMP WAS 83 º C PowerPoint Presentation: 13 EFFECT OF FLY ASH ON HARDENED CONCRETE AND DURABILITY STRENGTH DEVELOPMENT RESISTANCE TO FREEZE THAW SULFATE RESISTANCE COEEFICIENT OF THERMAL EXPANSION PERMEABILITY PowerPoint Presentation: 14 STRENGTH DEVELOPMENT USUALLY STRENGTH DEVELOPMENT IS VERY SLOW DUE TO POZZOLANIC REACTION OF FLY ASH LATER AGE STRENGTH IS HIGHER EXCEEDS THE STRENGTH OF CONCRETE WITH OUT FLY ASH ENOUGH CURING SHOULD BE AVAILABLE FOR LONG TIME FLY ASH UNDER WATER WILL BE MORE BENEFICIAL PowerPoint Presentation: 15 Typical strength gain of fly ash concrete    Source: www.flyash.info PowerPoint Presentation: 16 COEEFICIENT OF THERMAL EXPANSION FOR 40% REPLACEMENT OF FLY ASH THE COEFFICIENT OF THERMAL EXPANSION REDUCES BY 4% (Source: Malhothra and Berry,1986) PERMEABILITY REDUCED FLY ASH BLOCKS BLEED CHANNELS REACTING WITH LIME AND ALKALIS FILLING PORE SPACES INCREASED FINES AND REDUCED WATER CONTENT PowerPoint Presentation: 17 Permeability of fly ash concrete Source: www.flyash.info PowerPoint Presentation: 18 RESISTANCE TO FREEZE THAW SINCE MORE STRENGTH IS ATTAINED IT CAN WIH STAND MORE FREEZE THAW BECAUSE INTRUSION OF AIR VOIDS IS NOT THERE, FREEZE THAW EFFECT IS LESS SULFATE RESISTANCE CLASS F FLY ASH HAS IMPROVED SULFATE RESISTANCE CLASS F FLY ASH CONSUMES Ca(OH) 2 WHICH IS THE MAIN CAUSE OF SULFATE ATTACK PowerPoint Presentation: 19 DURABILITY OF FLY ASH CONCRETE SUFFICIENTLY CURED FLY ASH CONCRETE HAS A DENSE STRUCTURE AND HENCE MORE RESISTANCE TO DELETERIOUS SUBSTANCES THIS REDUCES THE CORROSION OF REINFORECEMENT CLASS F FLY ASH REDUCES ALKALI -SILICA REACTIVITY BECAUSE OF THE DENSE STRUCTURE AND HENCE EXPANSION IS REDUCED WHICH INCREASES DURABILITY BECAUSE OF THE REDUCED PERMEABILITY THE CHLORIDE INGRESS IS REDUCED PowerPoint Presentation: 20 UTILIZATION OF FLY ASH Fly ash mission project sites PowerPoint Presentation: 21 MANUFACTURE OF PORTLAND CEMENT ADDITIVE TO CEMENT AVAILABLE NEAR TO CEMENT PLANTS CEMENT CONCRETES CONSTRUCTION OF DAMS LINING OF TUNNELS AND CANALS BRIDGES PowerPoint Presentation: 22 SINTERING OF FLY ASH SOLID AND HOLLOW CONCRETE BLOCKS USED IN MULTI STORIED AND CHEAP HOUSINGS LIGHT WEIGHT AGGREGATES PowerPoint Presentation: 23 Sl. No Structures State Cement replaced (%) Source of fly ash 1. Gurgoan tunnel Haryana 15 Delhi 2. Jawar sagar Dam Rajasthan 20 Delhi 3. Kakki Dam Kerala 20 Neyveli 4. Navora barrage U.P. 15 Harduaganj 5. Rihad Dam U.P. 15 Bokaro 6. Sone Barrage Bihar 15 Bokaro 7. Umium Project Assam Not available Durgapur 8. Chandil dam Bihar 25 Talcher Fly ash utilization in Mass concrete or Dam construction PowerPoint Presentation: 24 Location Application Hindustan Prefab Ltd. Staff Quarters, New Delhi 15% replacement of fly ash in precast RCC components. Government double storied staff quarters R.K.Puram at New Delhi 20% fly ash in cement and mortar 4 storied Government quarters at dhaulakuan New Delhi 20% fly ash in cement and mortar Double storied building at the S.E.R.C.Chennai. Precast reinforced channel units Dwelling units at Pankha road, New Delhi Foundation, Concrete mortar flooring plaster some RCC items Flats at Besant Nagar, Chennai Cement mixture Fly ash Experimental Housing Schemes By National Buildings Organisation PowerPoint Presentation: 25 Use of flyash based cellular light weight aggregates at Hyderabad & Chennai PowerPoint Presentation: 26 Fly ash used in the construction of buildings at Chennai PowerPoint Presentation: 27 Buildings constructed using fly ash blocks at New Delhi PowerPoint Presentation: 28 Saraswati Sishoo Mandir School Near Dadri PowerPoint Presentation: 29 Fly ash used in Delhi Metro PowerPoint Presentation: 30 Fly ash used in Ready Mix Concrete (RMC) plants at Delhi PowerPoint Presentation: 31 Increased workability . Concrete is easier to place with less effort, responding better to vibration to fill forms more completely. Increased ease of pumping . Pumping requires less energy; longer pumping distances are possible. Improved finishing . Sharp, clear architectural definition is easier to achieve Reduced bleeding . Fewer bleed channels decreases porosity and chemical attack. Improved paste to aggregate contact results in enhanced bond strengths. ADVANTAGES PROPERTY WISE PowerPoint Presentation: 32 . Reduced segregation . Improved cohesiveness of fly ash concrete reduces segregation that can lead to rock pockets. Greater strength . Fly ash increases in strength over time, continuing to combine with free lime. Decreased permeability . Increased density and long-term pozzolanic action of fly ash, which ties up free lime, results in fewer bleed channels and decreases permeability. PowerPoint Presentation: 33 Increased durability . The lower permeability of concrete with fly ash also helps keep aggressive compounds on the surface, where destructive action is lessened. Fly ash concrete is also more resistant to attack by sulfate, mild acid, and soft water Reduced alkali silica reactivity . Fly ash combines with alkalis from cement that might otherwise combine with silica from aggregates, thereby preventing destructive expansion. Reduced heat of hydration . The pozzolanic reaction between fly ash and lime generates less heat, resulting in reduced thermal cracking when fly ash is used to replace a percentage of Portland Cement. PowerPoint Presentation: 34 CONCLUSIONS IMPROVED MEANS OF CLASSIFYING AND SPECIFYING FLY ASH SOURCES IS NEEDED CLASS F FLY ASH MIGHT NOT HAVE CEMENTATIOUS ABILITY,THIS HAS TO BE FURTHER BLENDED WITH OTHER BY PRODUCTS CAN BE SUGGESTED FOR HIGH PERFORMANCE CONCRETE HAS TECHNICAL ADVANTAGES AND ALSO COST BENEFITS OVER NORMAL CONCRETE, PAST AND PRESENT RESEARCHES HAVE HELPED IN BETTER UNDERSTANDING OF THE PRODUCT AND CAN BE UTILIZED EFFECTIVELY. PowerPoint Presentation: 35    References Shetty M. S. (2003), “Concrete Technology”, S.Chand & company. Ltd, New Delhi. Neville A. M. (1997), “Properties of Concrete”, Addison Wesley Longman, London. Malhotra V. M. (2003), “Hydration reactions and pozzolanic activity of fly ash”, ACC users manual-III, Bangalore. Ashok Dhariwal (1999), “Utilization of fly ash in scenario of 21 st century”, Proceedings of fly ash characteristics, Indian Institute of Science , Bangalore. www.useit.umeciv.maine.edu/ashcrete.html www.tfhrc.gov/hnr20/recycle/waste/cfa51.html www.flyash.info   PowerPoint Presentation: 36 THANK YOU

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