Technologies During Concreting for Watertight Structure Vijay Ranjan Zonal Head South Zone II

Transcription

1 Technologies During Concreting for Watertight Structure Vijay Ranjan Zonal Head South Zone II

2 Why Water tightness In Concrete Structures Is Important? Water seepage defeats a key objective of building Nuisance Unsafe e.g., From wet area on upper floor Electric shocks Algae / fungi growth unhealthy to sensitive persons (Asthma and Aids patients) Expensive Damage to goods food, medicines, cloth, cement, chemicals, paper, electronic, etc., Damage to finish - paint, gypsum and other such finishes expensive to rectify. TECHNICAL PRSENTATION ON SCC Ingress is also dangerous to structure! Vijay Ranjan Sales Manager ( BASF ss / Watertight India Str Ltd )

3 Scientific Approach To Watertightness Ingress needs (1) A water source and (2) A pathway in concrete for its transport. Paths taken by water Capillary porosity Inherent; impermeable at W/C<0.4 Defects -honeycombs Can be avoided with SCC or SDC Construction joints Can be minimised with SCC or SDC Expansion joints Essential; needs sealing Defects cracks Unpredictable; waterproofing membranes stop ingress If all five are avoided / sealed, structure will be watertight! TECHNICAL PRSENTATION ON SCC Solution-set for watertightness must address all the 5 paths Vijay Ranjan ss/trng - wp-lvl2/ 01/0408 Sales Manager ( BASF India Ltd ) 3

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5 Durability???

6 Design? Practice?

7 Durability???

8 What can we do?

9 Design Phase: Low Water Cement Ratio Low Porosity Concrete Cement Replacements

10 Batching - Coarse Aggregates

11 Batching - Water

12 Computerized Batching

13 Manual Transportation

14 Pumping of Concrete

15 Transit Mixer - 6 Cum

16 COMPACTION

17 Incorrect Concrete Compaction

18 Concrete Durability: What We Can t Do Workmanship Control!!!

19 Therefore. Minimize / Reduce the reliance on the human factor

20 Congested reinforcement

21 Durable Concrete SCC / SDC is the obvious answer.

22 Typical performance of water reducing admixtures Modified ligno sulphonates up to 8 % Melamine sulphonates up to 20 % Naphtalene Sulphonates up to 20 % Polycarboxylic ethers up to 40 %

23 Innovation History of Water Reducer Technology Volume of Admi ixtures Conventional AE water-reducing agent [Lignin, G-Na] High water-reducing agent [BNS, MS] Standard high range Super plasticizer [PCE] Tailored HRWR [PCE] Year

24 Development of strength 100 compressive stren ngth MPa with PCE based with traditional plasticizer With out admixture time [d ]

25 Design of PCE 3 rd generation of PCEs: tailored to application Plasticity retainer Water reducer Strength enhancer Viscosity controller

26 Design of PCE 3rd generation of PCEs: tailored to application Plasticity retainer Water reducer Strength enhancer Viscosity controller

27 Slump Loss At Start After 60 min

28 SCC -Definition Flowing concrete without segregation and bleeding, capable of filling spaces and dense reinforcement or inaccessible voids without hindrance or blockage. (by EFNARC, Technical Committee, Self Compacting Concrete, London 2000)

29 Imagine a site like this!

30 SCC Materials Normal concreting aggregates for structural concrete can be used. Coarse aggregates up to 40mm have been used very successfully. Maximum size of aggregate to be used depends on reinforcement layout in the same way as in traditional concrete.

31 SCC Materials Cement and fillers are required for cohesion and stability in larger proportions. Fillers like lime stone powder and cement replacements like GGBFS PFA, and Microsilica may be used. Fillers must be assessed for their effect on water demand.

32 SCC Admixtures Admixtures are necessary in determining flow characteristics and workability retention. Hyper plasticiser based on Poly- Carboxylated Ether Technology are specifically relevant to SCC. Admixtures will reconcile the conflicting requirements of flow and cohesion, avoiding potential problems with retardation, segregation and air entrainment.

33 PCE Admixture Side Chain Length Charge Center Main Chain Length

34 SCC- Requirements The workability of SCC is higher than the highest class of consistence described within EN 206 and canbe characterised by the following properties: Filling ability. Passing ability. Segregation resistance. A concrete mix can only be classified as Self-compacting Concrete if the requirements for all three characteristics are fulfilled.

35 Test Methods and Acceptability Criteria

36 SCC Mix Key characteristics and Needs High fines content, 500 to 650 kg/cum Consequently high water demand, exceeding 30% Coarse aggregates needed to keep in floatation Excess water eliminated Use of VEA or VMA

37 Fine Content in SCC 500 to 650 Kgs/M 3 of fines Particle passing 125 microns Can contain Flyash, Silica Fume etc Will require powerful admixture Poly Carboxylic Ether (PCE)

38 Network action of VMA Absence of a VMA in very fluid concrete Segregation Presence of a VMA in very fluid concrete Homogeneity

39 Viscosity Modifying Admixtures Viscosity-modifying admixture (VMA) - A material added to concrete that changes its viscosity and improves the stability of the mixture. Increasing Viscosity

40 The VMA Difference Rolling edge vs. Flat edge Aggregate particles have separated from mixture Aggregate particles are suspended within the mixture and are present all the way to the perimeter.

41 Self Consolidating Concrete Low fines approach possible Less shrinkage and lower creep Lower viscosity concrete than high fines Provides dynamic and static stability Paste Layer No VMA Aggregate at top With VMA

42 Tests on SCC Critical Properties Flowability Stability Passing ability There are a number of test methods: Slump- flow V-funnel L-box U-box J-ring Filling vessel test

43 Slump-flow FLOWING ABILITY STABILITY ( VIDEO)

44 V-FUNNEL FLOWING ABILITY STABILITY. (VIDEO)

45 L-BOX TEST Passing ability thro Obstruction (VIDEO -1) (VIDEO-2 )

46 U BOX TEST (VIDEO)

47 Application & Usage Places of Congested Reinforcement Difficulty of Placing Architectural Shapes Elimination Vibration Beam Column joints Columns & Walls Faster Construction (5 mtr-12 Mtr Lifts) Foundations & Basement water tightness Eliminate Cold Joints Faster Construction Overall Durability

48 SCC -Advantages Easily placed in thin-walled elements or elements with limited access. Can flow considerable distance horizontally and upwards to fill vertical elements from the bottom. Ease of placement can result in cost saving, through reduced equipments and labour requirements.

49 SCC -Advantages Reduced noise and vibrations during placement, resulting in high productivity. Improved surface finish no extra cost of making good. Highly durable concrete can be produced. More innovative designs, more complex shapes, thinner sections, etc. are possible.

50 SCC Vs conventional concrete

51 SCC Vs Conventional Concrete Mix

52 SCC VS Conventional concrete

53 SCC - WALLS

54 Traditional concrete to Self Compacting Concrete consolidated not consolidated consolidated not consolidated consolidated not consolidated plasticized concrete superplasticized concrete Self Compacting Concrete

55 Smooth Finish

56 DMRC, DELHI

57 DMRC -STATION DOME

58 Pre-Cast Panels for BIAL SCC with Glenium SKY

59 Finish achieved with SCC BIAL video

60 Second Vivekananda Bridge, Kolkata

61 The Second Vivekanada Bridge

62 MANERIBHALI HEPP

63 MANERIBHALI HEPP Top view of Surge Shaft

64 NPCIL, KAIGA

65 SCC - COLUMN

66 NPCIL, KOTA (RAPP) SCC in IDCT- shear walls, beams, columns & slab

67 RAPP, Kota Video

68 The two extremes Traditional Vibrated Concrete Self-Compacting Concrete High stability (+) Difficult to place (-) Poor consolidation (-) Highly flowable (+) High fines, hence shrinkage (-) High material cost (-)

69 Hurdles to use SCC SCC is ordered for its rheology. Its strength class is usually >35 because of the high cement content needed to maintain some stability (no segregation, no bleeding). In reality, the most requested classes of strength, are 20 to 35 MPa, corresponding to 86% of the total volume produced In India. Rheological properties have an extra cost due to 10 to 20 MPa in excess

70 Fluid Concrete Stability: This is the Problem In order to obtain stable and fluid concrete high content of fine particles is necessary: Usually not less than 550 to 580 kg of fines, fillers and cement. Usually not less than 400 to 450 kg / m 3 of cement contribute to the fines part of the concrete mix.

71 Smart Dynamic Concrete (SDC) Self Compacting Concrete of Up To M 40 SCC: Min 500kg C/m 3 i.e., high strength -> 40MPa Most concretes M20-M35, with lower cement SDC: Min 300kg C/m 3 Low to medium strength 20-40MPa All the benefits of SCC low W/C, no honeycombs, large pours, tall lifts (minimal joints), etc! Ordinary concrete made extraordinary! 71

72 SDC - Highly Sustainable And Economical Very durable W/C < 0.35 impermeable to most corrosive fluids -H 2 O, CO 2, Cl -, etc, ( Can be minimized ) Protects environment Allows high cement replacement with fly ash / GGBFC 1MT of cement clinker releases 1MT of CO 2 Utilises fly ash a dangerous pollutant Saves precious resources Over 50% water (W/C 0.45 to 0.30) Energy and labour Pumped long distances 2.7km, single stage pumping! e.g. in vibrating 72

73 18/06/

74 Thank You!