C T: Study and Uses of High Strength Concrete Unit 5 Part 1

Que5.1. What do you understand by high strength concrete?  Write down its advantages and disadvantages. 

Answer  High Strength Concrete For  fusions made with normal- weight   summations, high- strength concretes are considered to be those which  have compressive strengths in excess of 40 MPa. 

Advantages of HSC 

1. High compressive strength. 

2. Increases rental space. 

3. Reduces space  enthralled by columns. 

4. Reduces dead  cargo. 

5. Reduces  quantum of  sword. 

6. High rise  structures can be  make by reduced columns. 

7. To use the concrete service at early age,e.g., pavement in 3 days

C. Disadvantages of HSC 

1. Must be  moxie in selection of  constituents. 

2. Damaged at high temperature i.e.,  lower resistance to fire. 

Que5.2. bandy the guidelines to selection of accoutrements  for HSC. 

Answer  1. For the advanced target compressive strength of concrete, the  outside  size of concrete  named should be small, so that the concrete can come  more  thick and compact and less void  rate. 

2. Up to 70 MPa compressive strength can be produced with a good coarse   total of a maximum size ranging from 20 to 28 mm. 

3. To produce 100 MPa compressive strength  total with a maximum  size of 10 to 20 mm should be used. 

4. Concretes with compressive strengths of over 125 MPa have been  produced with 10 to 14 mm  outside size coarse  total. 

5. Using supplementary cementitious accoutrements ,  similar as blast- furnace sediment,  fly ash and natural pozzolanas, not only reduces the  product cost of  concrete, but also addresses the depression loss problem. 

6. The optimum negotiation  position is  frequently determined by the loss in 12 or  24 hour strength that’s considered  respectable, given climatic conditions  or the  minimal strength  needed. 

7. While silica cloud is  generally not really necessary for compressive strengths  under 70 MPa,  utmost concrete  fusions contain it when advanced strengths  are specified. 

Que5.3. What are the  colorful  styles to achieve high strength  in concrete? Also  bandy their  operations. 

Answer  styles to Achieve High Strength in Concrete Following are the  special  styles to achieve high strength in concrete 

1. sowing This involves adding a small chance of finely ground, completely  doused  Portland cement to the fresh concrete  blend. This  system may  not hold  important  pledge. 

2. Revibration Controlled revibration removes all the  blights like  bleeding, water accumulates, plastic  loss,  nonstop capillary  channels and increases the strength of concrete. 

3. High Speed Slurry Mixing This process involves the advance  medication of cement- water admixture which is  also blended with   total to produce concrete. 

4. Use of cocktails Use of water reducing agents are known to  produce increased compressive strength. 

5. Sulphur Impregnation Satisfactory high strength concrete have  been produced by  macerating low strength  pervious concrete by sulphur. 

6. Inhibition of Cracks If the propagation of cracks is inhibited, the  strength will be advanced. Concrete  cells made this way have yielded  strength up to 105MPa. 

Applications of High Strength Concrete 

1. High strength concrete is  needed in engineering  systems that have  concrete  factors that must  repel high compressive loads. 

2. High strength concrete is  generally used in the construction of high- rise  structures. 

3. It has been used in  factors  similar as columns( especially on lower   bottoms where the loads will be  topmost), shear walls, and foundations. 

4. High strengths are also  sometimes used in ground  operations as well. 

5. High strength concrete is  sometimes used in the construction of  trace  islands. 

6. Use of HSC in column section decreases the column size. 

7. Use of HSC in column decreases  quantum of  sword  needed for same  column. 

8. In high rise  structure, use of HSC increases the  bottom area for rental  purpose. 

9. In islands, use of HSC reduces the number of  shafts supporting the  arbor. 

Que5.4. What’s  tone compacting concrete? What are the   parcels, advantages and disadvantages of  tone compacting  concrete? 

Answer  tone Compacting Concrete It’s defined as “ a concrete that’s  suitable to  inflow under its own weight and  fully fill the formwork, while  maintaining unity indeed in the presence of congested   underpinning, and  also consolidate without the need for  wobbling    contraction ”.  Properties of SCC In fresh state, SCC have the following  parcels .

Filling Capability Flows  fluently at certain speed into formwork. 

2. Passing Capability Passes through  underpinning without blocking. 

3. isolation Resistance The distribution of aggregate  patches  remains homogeneous in both  perpendicular and vertical direction. 

Advantages of SCC Following are the advantages of SCC 

1. A faster rate of placing, without vibration. 

2. bettered pumpability. 

3. bettered  connection around  underpinning. 

4. Reduced permeability. 

5. Reduced wear and tear and gash on forms from vibration. 

6. Improves the quality,  continuity, and  trustability of concrete structures  due to better  contraction and unity of concrete. 

7. Ease of placement results in cost savings through reduced  outfit  and labour  demand. 

8. lower noise from vibrators and reduced  peril from hand- arm vibration  pattern( HAVS).

9. Improves working conditions and productivity in construction assiduity. 

10. Reduced construction period. 

11. Elimination of problems associated with vibration.  Disadvantages of SCC Following are the disadvantages of SCC 

1. More  strict conditions on the selection of accoutrements . 

2. Lack of encyclopedically accepted test  norms and mix designs. 

3. premium than conventional concrete grounded on concrete material cost  exception to placement cost). 

4. Requires  further trial batches at laboratory as well as at ready-mixed  concrete  shops. 

5. More precise  dimension and monitoring of the  element accoutrements .

Que5.5. Explain the accoutrements  used for  tone compacting concrete.  Also give its  operations. 

Answer  Material needed for SCC Following are the  colorful material   needed for making SCC 

1. Cement Ordinary Portland cement of 43 or 53 grade can be used. 

2. summations Well  canted boxy or rounded  summations are desirable. 

3. Water Quality Maintained same as  corroborated concrete. 

4. Chemical cocktails Super plasticizers particularly polycarboxylated  ethers are used in SCC. 

5. Mineral cocktails Following are the mineral  cocktails used is  SCC  Fly Ash It improves the quality and  continuity of concrete.

ii. GGBFS It improves rheological  parcels(semi-solid and liquid  state). 

iii. Silica Cloud It improves mechanical  parcels. 

iv. Stone Powder Finely crushed limestone, dolomite,  determinedness may  be added to increase greasepaint content. 

Application of SCC Self compacting concrete is ideal to be used in the  following  operations 

1. It has been used in islands and indeed onpre-cast sections. 

2. Drilled shafts. 

3. Column. 

4. Earth retaining systems. 

5. Areas with high  attention of rebar and pipes conduits,etc.

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