Development and Application of High Volume Fly Ash Concrete (HVFAC) (Case Studies of Some Demonstration Projects) (Grasim Experience)

Transcription

1 Development and Application of High Volume Fly Ash Concrete (HVFAC) (Case Studies of Some Demonstration Projects) (Grasim Experience)

2 High Volume Fly Ash Concrete in Marine Construction Work in Mumbai

3 What is High Volume Fly Ash Concrete? (HVFAC) IS: , Code of Practice for Plain and Reinforced Concrete allows replacement of OPC by Fly ash upto 35% as binding material. This provision is in conformity to IS 1489 (Part I), Code of Practice for Portland Pozzolana Cement where fly ash is allowed to replace OPC upto 35% in PPC. Concrete produced in conformity to IS 1489 (Part I)and IS: is referred as Normal Concrete Further classification Ordinary, Standard and High Strength is based on its Compressive strength. HVFAC on the other hand is a concrete in which fly ash is used in excess of 35% as replacement of OPC as binding material

4 Need for developing HVFAC Abundance of Fly Ash in India India produces about 110 million tons of fly ash per year. Disposal of such large quantity is posing ecological and environmental problems Quality of Fly Ash Indian fly ashes from Major Thermal Power Plants (TPP) are of very high quality (LOI<2%, blaines 3000 and low variability). They are very good pozzolans

5 Need for developing HVFAC Economic Factors Cost of fly ash with in 200 km from a TPP is as low as 10% to 20% of the cost of cement. Concrete requiring 400 kg / m 3 binding material, may result in saving of 15% to 18% in overall cost of concrete with 45% to 50% replacement by fly ash Environment Factors. Reduction in CO 2 emission (Production of 1 ton clinker releases about 1ton CO 2 ) Nearly 1.5 to 1.8 million tons FA is generated per year by 1000 MW, TPP. Requires about 160 acres land / year for disposal. India has installed TPP capacity about 70,000 MW, likely to touch 100,000 MW by 2012

6 Expected Growth of concrete Industry in India 400 M illio n m Year Note: Construction industry is expected to grow during Tenth Five Year Plan at 10% to 12% per annum. Cement and concrete industry are expected to grow during this period 8% to 10%.

7 Expected utilization of fly ash in HVFAC M illio n m H V F A C C o n c r e te in m illio n m 3 25% F ly A s h in M illio n T o n s % % % 5% Year

8 * * * * * * Workability Compressive Strength Flexural Tensile Strength Permeability Abrasion resistance Cost of Production Expectations from HVFAC Ease of placement Continued gain of strength and equivalent to control concrete at 45 days. To surpass control concrete at 45 days by 10% 30% Lower than control concrete at 28 days and 50% at 45 days 10% higher than control concrete at 45 days 20% cheaper than control concrete for the same grade

9 Salient Features * * * * Length of road Width of road Grade of concrete Demonstration Project Thickness of Pavement Quality Concrete (PQC) m 7.2 m 260 mm M40 * Total volume of HVFA Concrete 238 m 3

10 Physical Properties of cementitious materials Physical Characteristics OPC 43 grade (IS: 8112) Fly Ash (IS: 3812) (Part I) 2003 Specific gravity (g/cm 3 ) Specific Surface (m 2 /kg) Compressive Strength (MPa) 3 day 7 day 28 day Compressive strength activity (%) Lime Reactivity (MPa) Soundness by autoclave (%) Drying shrinkage (%)

11 Chemical Properties of cementitious materials Chemical Characteristics Silicon dioxide, SiO2 (%) Magnesium Oxide, MgO (%) Total alkalies as Na2O (%) Sulphur Trioxide, SO3 (%) Loss on Ignition (%) Total Chlorides (%)

12 Grading of Coarse and Fine aggregates Coarse Aggregate Fine Aggregate Limits Zone II Sieve Size, mm 40 mm Passing, % 20 mm Passing, % 10 mm Passing, % Sieve Size, mm Passing, % Passing, %

13 Trial Mixes with High Volume Fly Ash 10 mixes were developed details are given in the paper 4 trial Mixes (2 with 40 mm MSA and 2 with 20 mm MSA) are highlighted Trial No. Cement kg Fly ash kg Sand kg 10 mm kg 20 mm kg 40 mm kg Water lit W/C Admix tures lit Slump mm Compressive Strength (MPa) 7 day 28 day Admixture Sulphonated Naphthalene Condonsate (SNF) with Solid Content 42% and relative density 1.23 was used

14 Trial Mix with out Fly Ash For comparison purpose, in a portion of road control concrete (M40 grade) was used. For control concrete, following mix design was used: Trial No. Cement kg Fly ash kg Sand kg 10 mm kg 20 mm kg 40 mm kg Water lit W/C Admixtures lit Slump mm Note 7 day average compressive strength was about 40 MPa and 28 day 53 MPa

15 Birla Ready Mix Concrete Plant, Miyapur Hyderabad

16 HVFAC Road Construction (GRASIM Experience)

17 Test Results of Hardened concrete Mix Type Compressive Strength, Mpa Lab. Specimens Cores Flexural strength, Mpa Split tensile strength, MPa Lab. Specimens Water permeability m/sec 7d 28d 56d 74d 74d 56d 56d 56d OPC x10 10 HVFA 20mm (MSA) x10 11 HVFA 40mm (MSA) x10 11

18 Water 56 days 3E10 3E10 2.5E10 2E10 m/ sec 1.5E10 1E10 5E11 3E11 2E11 0 Water Permeability A B C M 40 Grade with 40 mm MSA (HVFAC) M 40 Grade with 20 mm MSA (HVFAC) M 40 Grade with 40 mm MSA (Control Mix)

19 Evaluation of other parameters of hardened concrete Type of concrete Percentage weight loss in H 2 SO 4 for 60 days Percentage weight loss in HCl for 60 days Percentage weight loss in Na 2 SO 4 for 60 days HVFA concrete OPC concrete

20 Strength relation between control and fly ash concrete Source CMA publication on NH4, Satara Kolhapur Road.

21 Permeability relation between control and fly ash concrete Source CMA publication on NH4, Satara Kolhapur Road.

22 Rise in Temperature in OPC and HVFAC concretes T = CH Where T = Temperature rise in ºC due to heat generation S C H = = Proportion of Cement in concrete by weight Heat of hydration of Cement at 7 days in Cal/g S = Specific Heat of Concrete Cal/g/ ºC Case I Only OPC Cement Weight of concrete = = 400 kg/m kg/m 3 C = Or T = = X ºC

23 Case II 50% replacement of cement by Fly ash (Heat of Hyderation of fly ash = 0.4 times of cement) C T = = = (0.4 X 200) = X ºC Inference By 50% replacement of fly ash, temperature rise is reduced by about 33%

24 Cost Comparison of HVFAC visàvis control concrete HVFAC with 37.5% replacement of cement by fly ash (150 kg in 400 kg) was found 18% cheaper than control concrete Fly ash River Sand Stone aggregate 40 mm 10 mm 20 mm Water Materials Cement (OPC 43 Grade) Kg/ m HVFAC Rs./ m Note: The cost/ m 3 has been arrived based on rates of material at Hyderabad during Nov., ADMIXTURE Cost/ m Kg/ m OPC Rs./ m

25 Precautions Recommended in use of HVFAC Regular check on quality of fly ash (LOI, Fineness, Reactivity) Collection, Transportation and dozing arrangements of Dry Fly Ash from TPP to batching plant. Proper weighbatching and mixing arrangement at the batching plant (preferably pan mixer). Adequate care during initial stage (especially upto 10 hours) to avoid Plastic Shrinkage Cracks. Wet curing preferably for a period of 14 days.

26 High Volume Fly Ash Concrete Road

27 High Volume Fly Ash Concrete Road

28 Space Needle Ecstasy in Concrete

29 Diablo Dam Ecstasy in Concrete

30 Lake Vranov footbridge Ecstasy in Concrete

31 Hulme Arch in Manchester, UK Ecstasy in Concrete

32 Conclusion Use of HVFAC is very suitable for tropical and hot climate countries like India Abundant availability of Fly Ash makes HVFAC more economical, environmental and ecological friendly product. It can be effectively used in structural and nonstructural applications where normal concrete is used. HVFAC wins over normal concrete in almost all Technical parameters. Use of HVFAC should be included in National Codes and in specifications of major construction departments / Companies. Concerted efforts by Thermal Power Plants, Construction Organizations, Academic Institutions and National bodies are solicited for promotion of HVFAC in Coming years.

33 Thank You