EFFECT OF RECRON FIBRES ON FLEXURAL BEHAVIOR ON CONCRETE

G.SUBASH-13BCL0306 M.PRASANTH-13BCL0302 K.PALPANDI-12BCL0265

GUIDED BY: Prof.Dr.SOUNTHARAJAN V.M

GROUP MEMBERS:

To minimize the construction cost . Reduce the quantity of cement for using agriculture waste,

etc. Improve the compressive, flexural & tensile strength of

concrete. Cracking, shrinkage and failure modes of concrete should be

reduced.

OBJECTIVES:

This research is aimed at putting into effective use Rice Hush Ash,Marble powder,Fly ash,GGBS(Ground Granulated Blast-Furnace slag), local additive which has been investigated to be super pozzolanic in a good proportion to reduce the high cost of structural concrete. Rice Husk Ash (RHA) is an agricultural waste product, and how to dispose of it is a problem to waste mangers. While Concrete today has assumed the position of the most widely used building material globally. The most expensive concrete material is the binder (cement) and if such all-important expensive material is partially replaced with more natural, local and affordable material like RHA ,Fly Ash,GGBS,Marble powder will not only take care of waste management but will also reduce the problem of high cost of concrete and housing.

INTRODUCTION:

In this method we are introducing recron fibres to concrete to check the behaviour changes in concrete and also try to getting high strength like( compressive,flexural,split tensile strength).Because due to the following reasons,1.fibre reduces the water permeability.2.increase the flexural strength due to have higher modulus of elasticity compared to that concrete or mortar binder.3.its post cracking behaviour helps to continue to absorb energy as fiber pull out.

4.increases energy absorption capability of concrete.5.Improves homogeneity of the concrete by reducing segregation of aggregates.

M40 Design as per IS code 10262-2009

Mix proportion 1:1.65:2.42:0.4

DESIGN:

Cement opc-53 grade Coarse aggregate-(20mm size) Fine aggregate Recron Fiber-(0.5%,1%,1.5%,2%)

MATERIALS USED & EXPERIMENTAL METHOD:

Tenacity (adequate strength) Flexibility or pliability Uniformity. Fiber morphology Specific gravity Elongation and elastic recovery Resiliency Moisture regain` Electrical conductivity Abrasion resistance Chemical reactivity and resistance Sensitivity to environmental conditions.

PROPERTIES OF RECRON:

The compressive strength is the capacity of a material or structure to withstand loads tending to reduce size.

It can be measured by plotting applied force against deformation in a testing machine

Compressive strength is a key value for design of structures.

COMPRESSIVE STRENGTH:

σ=P/A P=Axial load (KN) A=Area of specimen (m²). σ=compressive stress(KN/m²).

Calculation for compressive strength:

Flexural strength, also known as modulus of rupture, bend strength, or fracture strength, a mechanical parameter for brittle material,

It is defined as a material's ability to resist deformation under load.

The transverse bending test is most frequently employed, in which a specimen having either a circular or rectangular cross-section is bent until fracture or yielding using a three point flexural test technique.

The flexural strength represents the highest stress experienced within the material at its moment of rupture.

FLEXURAL STRENGTH:

Flexural testing machine:

FB= PxL/(bxd²)Where, P=axial load (kN) L=length of specimen (m) b=breadth of specimen (m) d=depth of specimen (m)

Calculation for flexural test:

Split tensile strength-Placing cylinder horizontally between the load.

surfaces of a compression testing machine Load is applied until specimen fails along the

vertical diameter

SPLIT TENSILE STRENGTH:

Compressive loading machine:

Cube=100mmx100mmx100mmRectangular=500mmx100mmx100mmCylindrical=100mmx200mm Based on this the amount of concrete required for the cube or rectangular are calculated.

The tested specimen has different strength at 7&28 days are calculated using of the apparatus.The results are tabulated .The strength of recron fiber reinforced concrete is greater than the reinforced concrete observed from the results.GRAPH:X-axis=% of recron fiberY-axis=compressive, flexural, tensile (N/mm^2) 

RESULTS &GRAPH:

Compressive strength:

Type of concrete

load applied(KN)

7 days curing

load applied(KN)

28days curing

concrete 0.218 21.8 0.3575 35.750.5%

recron0.2234 22.34 0.3575 35.75

1% recron 0.231 23.10 0.3706 37.061.5%

recron0.2572 25.72 0.3880 38.80

2% recron 0.2616 26.16 0.3924 39.24

Compressive strength(N/mm^2)

Flexural strength:

Type of concrete

7 days curing

load applied(KN)

28 days curing

load applied(KN)

concrete

3.48 0.174 4.5 0.225

0.5% recron

3.78 0.189 4.86 0.243

1% recron

4.45 0.222 5.22 0.261

1.5% recron

4.62 0.231 5.4 0.27

2% recron

5.46 0.273 6.07 0.3035

Flexural strength (N/mm^2)

Split tensile strength:

Type of concrete 7 days

curingload

applied(KN)28 days

curingload

applied(KN)

concrete 2.64 0.3317 4.16 0.5227

0.5% recron 2.78 0.3493 4.44 0.5579

1% recron 3.05 0.3832 4.72 0.5931

1.5% recron 3.47 0.4360 4.85 0.6094

2% recron 3.75 0.4712 5.13 0.6446

Split tensile strength(N/mm^2)

Target Mean strength for mix design:The target means compressive (ḟck) strength at 28 days is given

by ḟck =fck+tSwhere as,S=standard deviation=5(As per IS code456 of 2000)t=1.65 a statical value depending on expected proportion of low

results (risk factor)as per IS code 456-2000 & IS code 1343-80.fck=characteristics of compressive strength at 28 days.

1.ḟck=35.75+(1.65x5)=44( N/mm^2).2. ḟck=37.06+(1.65x5)=45.31( N/mm^2).3. ḟck=38.8+(1.65x5)=47.05( N/mm^2).4. ḟck=39.24+(1.65x5)=47.49( N/mm^2). 

An experimental study was conducted on cubes, cylinders, beam, for compressive, split tensile strength, flexural test respectively by mixing various percentages of recron fiber. Based on the investigation the following conclusions were drawn. They areThe Compressive Strength of Reinforced Concrete was less than Recron Fiber Reinforced Concrete at all percentage of mix.The Split Tensile Strength of Reinforced Concrete was less than Recron Fiber Reinforced Concrete at all percentage of mix.The flexural strength of reinforced concrete was less than recron fiber reinforced concrete at all percentage of mix. Hence, Recron Fiber has greater strength in Compression, Split Tension and Flexure. 

CONCLUSION:

Shah RH, Mishra SV. Crack and deformation characteristics of SFRC dep beams.Institution of Engineers (India) Journal of Civil Engineering, 85(2004) 44-8.Sachan AK, Kameswara Rao CVS. Behaviour of fibre reinforced concrete deep beams.Cement & Concrete Composites, 12(1990) 211-8.

REFERENCES:

Shanmugam NE, Swaddiwuuhipong S. The ultimate load behaviour of fibre reinforced concrete deep beams. Indian Concrete Journal, No. 8, 58(1984) 207-11.Shanmugam NE, Swaddiwuuhipong S. Strength of fibre reinforced concrete deep beams containing openings. International Journal of Cement Composites and Lightweight Concrete, No. 1, 10(1988) 53-60.

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P.Baruah & S.Talukdar, (2007)”A Comparative study of compressive, flexural, and shear strength of concrete with fibres of different origins”, The Indian Concrete Journal, Vol.75,No. 4,pp 17-24. Arnon Bentur & Sidney Mindess, (1990) „„ Fibre reinforced Cementitious composites‟‟ Elsevie applied science London and Newyork Rathish Kumar P. et al Vibration characteristics of fibre reinforced self Compacting mortar (FRSCM) (2.7). Nataraja,M.C.,Dhang,N.,and Gupta,A.P. (2001),”Splitting tensile Strength of SFRC”,The Indian Concrete Journal, ,Vol.75,No.4,pp 287- 290. 

Indian Standard methods of tests for compressive strength and flexural strength of concrete ,IS 516:1959, Bureau of Indian Standards, New Delhi.Anthony J. et al, May-June 2001. Flexural Strengthening of R.C Beams Using Fasteners and Fibre Polymer Strips “ACI Structural Journal” Page No: 368 to 376 

 

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