* BAMBOO REINFORCED CONCRETE Guided by PIJUS KANTI MANDAL LecturerPresented by PEKASO SADHUKHAN ROLL NO. 17776

It is estimated that about 20 million ha in 50 countries

are irrigated with raw or partially treated wastewater.

The area irrigated with waste water varies around 10 %

of the total world irrigated area

*What is Wastewater (WW) Wastewater (WW) is a combination of the liquid, or water carried wastes , removed from domestic , institutions, commercial and industrial establishments together with surface/ ground/storm water.

It is estimated that about 20 million ha in 50 countries are irrigated with raw or partially treated wastewater. The area irrigated with waste water varies around 10 % of the total world irrigated area

*Waste Water Categories Water treated after domestic & public uses Industrial Waste Water Saline agricultural drainage water Brackish ground water Sea water in coastal regions

*Components of Wastewater Suspended solids Soluble/ biodegradable organic matters Inorganic soluble salts Ca, Mg, Na, K, B, CL, carbonates and sulphides Plant micro-nutrients N, P, K Faecal pathogenic micro-organisms Trace elements: Heavy metals: As, Cd, Cr, Cu, Pb, Hg, Zn Inorganic elements: Al, Be, Co, F, Fe, Li, Mn, Mo,Se, Sn, Ti, W and V

*VARIOUS SPECIES OF BAMBOO

*PREPARATIONSizing

Splitting

Seasoning

Bending

Waterproof Coating

*CONSTRUCTION PRINCIPLES

Concrete Mix Proportions The same mix designs can be used as would normally be used with steel reinforced concrete. Concrete slump should be as low as workability will allow. Excess water causes swelling of the bamboo. High early-strength cement is preferred to minimize cracks caused by swelling of bamboo when seasoned bamboo cannot be waterproofed.

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Placement of bamboo

Bamboo reinforcement should not be placed less than 1 inches from the face of the concrete surface. The clear spacing between bamboo rods or splints should not be less than the maximum size aggregate plus inch.Reinforcement should be evenly spaced and lashed together on short sticks placed at right angles to the main reinforcement.The ties can be maid with vegetation strips.This embedded depth is approximately 10 times the diameter of whole culms or 25 times the thickness of inch wide splints. Spacing of the stirrups should not exceed 6 inches.

*DESIGN PRINCIPLES

Bamboo reinforced concrete design is similar to steel reinforcing design. Bamboo reinforcement can be assumed to have the following mechanical properties.

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Mechanical properties of bamboo reinforcementMechanical PropertySymbolValue (psi)Value (psi)Ultimate compressive strength---8,000Allowable compressive stresss4,000Ultimate tensile strength---18,000Allowable tensile stresss4,000Allowable bond stressu50Modulus of elasticityE2.5x106

*When design handbooks are available for steel reinforced concrete, the equations and design procedures can be used to design bamboo reinforced concrete if the above mechanical properties are substituted for the reinforcement.

*BEAMS AND GIRDERS Bamboo longitudinal reinforcement should be between 3 and 4 percent of the concrete cross section.It have the same bending moment resistance coefficient as a balanced steel reinforced beam, singly reinforced. Economy of concrete increases going to the left on the curve; therefore, deeper, narrower replacement beams are recommended. A minimum number of rods should be used to provide adequate spacing. The bamboo stirrup area should always be about 4 times the steel stirrup area.

*Example Design of Bamboo Reinforced Beam:Design a bamboo reinforced concrete beam to span 2.43m and to carry a uniform dead load plus live load of 450 KN/m and two concentrated loads of 108 KN each symmetrically located 0.6m each side of the center line of span. Assume the ultimate strength of the concrete is 240KN/m2; the allowable compression stress is 108 KN/m2 Allowable unit diagonal tension stress,V , in the concrete is 72 KN/m2. Allowable tension stress, s, in the bamboo is 400 KN/m2; the allowable unit bond stress between bamboo and concrete is 40 KN/m2.

* Solution

At the intersection of the allowable stress curves for concrete and bamboo, find R = 115 and p = 3.1 percent.

2. Maximum bending moment, M, is given by: M = [450(2.43)2(12)]/2.43 + 108(0.6)(12) =13899.6 KN m. R = M/bd2

3. From bd2 = 13899.6/115 = 120.86 m3

4. If b = 2.43m. is chosen, then d = (120.86(10)/2.43) = 7.05mm.

5. Bamboo reinforcement = pbd = 0.031(2.43)(7.05) = 4.75

6. Use -inch-thick splints, area = 0.563 m2. Number required = 4.75/0.563 = 8.4; round up to 9. Space evenly in three rows. Bend up top row randomly in the outer one-third ends of the beam.

* 7. Check the bond stress. Maximum shear at the support, V, is determined as: V = 450(2.43)/2 + 108 = 860 KN/m2.The perimeter of one splint is 4(3/4) or 3 m.; the total perimeter of the longitudinal reinforcement, 0, is 9(3) = 27 m. The value of j = 0.925 u = V ojd = 654.7 27(0.925)(7.06) = 13 KN/m2This is less than the allowable bond stress of 40 KN/m2.8. Calculate the shear, V', taken by the concrete fromV' = bjd = 72(2.4)(0.925)(4.75) = 759.2 KN/m2Where is the allowable diagonal tension stress of the concrete.9. Provide 0.4 mm thick splints for stirrups. The area provided by one stirrup bent into a U-shape, A, is 4(0.4) = 1.6 mm2 (Stirrup area 4 times the dia). Maximum spacing, s, is given by:s = Ajd (V - V') = 1.6(400)(0.925)(4.75) (860 759.2) = 10.1mm.

Common practice is to include two additional stirrups past the point where diagonal tension reinforcement is not needed.

*COLUMNS Bamboo reinforcement in columns serves to resist a compression load equal to that taken by the concrete it displaces; it also will resist shear and tensile stresses. Of the full cross section of concrete, only 80 percent is considered effective in rectangular tied, columns. Allowable concrete stress should not exceed 0.225 f'c where f'c is the ultimate compressive strength of the concrete.Vertical reinforcement should be approximately 4 percent of the column cross section for rectangular columns. When bamboo is used as lateral tie reinforcement, the ties should be spaced not over 16 times the least dimension of the vertical reinforcement nor farther apart than the least dimension of the column.

*ExampleDesign of Bamboo Reinforced ConcreteColumn:Determine the cross section and bamboo reinforcement of a column required to carry an axial load of 700 KN. Ultimate compression strength of the concrete, 240.KN/m2Solution:1. For an unreinforced rectangular column the safe axial load, P, is given by:P = 0.8Ac (0.225 f'c)Where Ac is the cross-sectional area of the concrete column and f'c is the ultimate compressive strength of concrete. 2. The column should have a cross-sectional area of:Ac = 700 0.8 (0.225) (240)(10) 3 = 16.20 m2.

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3. If a square column is chosen, it will have face dimensions ofb = (16.20) = 4.0 m

4. The amount of vertical reinforcement should be 4 percent of the concrete area .These should be spaced evenly around the perimeter of 1 to 1 mm of cover. Provide each vertical splint with a 90-degree corner.

*COMPARISON OF BAMBOO AND STEELThe strength of bamboo is greater than steel.Bamboo is easily accessible. Bamboo lowers the cost of construction. Increases the strength of the buildings .Bamboo can crack and deflect more than steel reinforcement.

*Other Applications Of BambooBamboo bridge in the Amsterdam Woods

* Bamboo theatre during the Festival of Vision, Berlin, 2000

* Bamboo scaffolding at the top of a new high-rise building in Hong kong

*CONCLUSION

The environmental and financial comparison demonstrates that bamboo can compete with building material. Bamboo is a natural product and will therefore always have some extent of irregularity. It is therefore suggested that the bamboo culm should be used in functions were the measurement requirements are not entirely precise or fixed, as in temporary buildings (e.g., pavilions and tents) or small civil projects. Furthermore, bamboo can play a role as a non-supporting or finishing material.

*REFERENCES

1. H. E. Glenn. "Bamboo reinforcement in portland cement concrete," Engineering Experiment Station, Clemson Agricultural College, Clemson, South Carolina, Bulletin No. 4, May 1950. 2. U. S. Army Engineer Waterways Experiment Station. Technical Report No. 6-646: "Precast concrete elements with bamboo reinforcement," by E. F. Smith and K. L. Saucier. Vicksburg, Mississippi, May 1964. 3. S. R. Mehra and R. G. Ghosh. "Bamboo-reinforced soil-cement," Civil Engineering and Public Works Review, Vol. 60, no. 711, October 1965; vol. 60, no. 712. November 1965. 4. "Concrete floors on ground," Portland Cement Association Concrete Information, ST-51. 5. American Concrete Institute. "Building code requirements for reinforced concrete," (ACI 318-56). May 1956. 6. Department of the Navy, Bureau of Yards and Docks. Design Manual NAVDOCKS DM-2, Structural Engineering. October 1964.

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