International Journal of Scientific & Engineering Research, Volume 4, Issue 12, December-2013 850

ISSN 2229-5518

FLEXURAL BEHAVIOUR OF SELF COMPACTING AND SELF CURING CONCRETE

BEAMS

B.VI DIVELLI 1, T.KATHI RAVAN 2, and T.GOBI 3

2 Professor, Department of Civil & Structural Engineering, Annamalai University Chidambaram.

3 Research Scholar, Department of Civil & Structural Engineering, Annamalai University.

Assistant Professor, Department of ci vil engineering-V.R.S College of Engg & Tech, Vilupuram.

E-Mail:

kathir5070@gmail.com

Abstract: The objective of this study is comparing the flexure behaviour of self compacting concrete beams. This research is proposed to replace the constituent materials by mineral Admixtures and adding chemical admixtures. Also it is proposed to use self curing compound instead of conventional water curing. Many researchers studied about the self compacting concrete only and not for self compacting and self curing concrete, but this study proposed a methodology for self compacting and curing concrete beams. Mechanical properties such as com- pressive strength, split tensile strength, modulus of concrete have been found out and compared with controlled beams, self compacting con- crete beams, self curing concrete beams and admixture beams. Beams in size of 125mm×250mm×1000mm were cast and tested to analyze the behaviour. The ANN modelling has compared the flexural behaviour of beams at various stages such as yield load, ultimate load and de- flection.

Keywords: ANN, fly ash, Self compacting concrete, self curing concrete.
——————————  ——————————

1 INTRODUCTION

IJSER

The self-compacting concrete (SCC) is the newest innovat-
ing category of high performance concrete, characterized by its abil- ity to spread and self consolidation in the formwork exhibiting any significant separation of constituents. Elimination of vibration for compacting concrete during placing with the use of Self Compacting Concrete leads to substantial advantages related to better homogenei- ty, enhancement- of working-environment and improvement in the productivity by increasing the speed of construction. Replacement of cementanious material like fly ash has increased the paste content and hence enhance the fresh and strength properties. Partial replace- ment of metakaolin with silica fume helped attaining high earlier strength of around 50-70 Mpa of SCC. Contribution of steel fibers in SCC improve the durability properties like permeability, water ab- sorption, abrasion resistance, resistance to marine as well as a sul- phate attack. Fibers resists all type of attack with in tolerable limits and the optimum dosage of fibers have promoted the better perfor-
mance.
agent.
(iii) Studies are done in different ways for the development of SCC
with different materials. I
(iv)Flexure behaviour of beams and formulate the modelling by us- ing artificial neural network.

2. Materials used:

The percentage of all replacement materials has been worked out from the trial and error method .lime stone powder was replaced by
10%, class c-fly ash is 20%, silica fume5% with cement and quarry dust was replaced by20% of fine aggregates. Super plasticizer con- plast SP430, high range water reducing admixtures of 0.80 li- tres/100kg of cementitious material. viscosity modifying agent (VMA) is a self compacting admixture, no need external vibration. enfiiq was used as self curing admixtures to achieve the self curing effects.
In past decades, the effect of self curing concrete possesses improved properties while comparing to identically cured controls. It was found that, initial surface absorption, chloride ingress, carbona- tion, corrosion potential and freeze and thaw resistance characteris- tics were comparatively better by air cured self-cure concrete than the air cured control.
This paper presents the experimental work which includes the mate-
rials used and the testing procedure adopted comparison of analytical to experimental, discussion on test results.

1.1 Objectives: (i) In this study to evaluate the effectiveness of var- ious percentages of mineral and chemical admixtures in producing self compacting concrete and self curing concrete.

(ii)Its flowing characteristics depend on the correct proportioning of ingredients and dosage of super plasticizer/viscosity modifying

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3. Experimental work:

(a)Fresh properties:
The slump flow test is the most widely used method for evaluating concrete consistency in the laboratory and at construction sites. The consistency and workability were evaluated using the slump flow, U Box, L-Box, J-Ring, V funnel and fill box tests .The slump flow of SCC concrete was in the range of 650-800 mm, which is an indica- tion of a good deformability. The time to reached 500 mm slump was in the range of 3-5 s, the J Ring was in the range of 3-8mm, the fun- nel test flow time was in the range of 3-7 s ,the v funnel test flow after 5 minutes was in the range of 6-12 s, L-box is range in the of
0.8-1.0.The fresh properties of SCC are summarized.
(b) Mechanical properties:
The mechanical properties like compressive strength, flexural strength, split tensile and modulus of elasticity of SCC were obtained from 150 x 150 x 150 mm cubes, 100x 100 x 500 mm prism and 150 x 300 mm cylinders and the results are summarized in (Table 3)
The experimental work on casting the structural elements of the size of beam specimen 1000mm length, 125mm width, 250mm depth. Two beam of conventional concrete, two beam of admixtures con- crete, two beams self compacting concrete, and self curing concrete elements were casted and tested.

3.1Compressive strength of specimens: Compressive strength tests were carried out on cubes of 150 mm size on a compressive testing machine of 2000 kN capacity as per IS516:1959

Fig 1. Specimen in compressive testing machine (cube)

Table 1. Compressive strength of specimen

Types of specimen	Weight of spec- imen in kg	Ulti- mate load in kN	Average Compres- sive strength N/mm2
Conventional con- crete	8211	733	32.59
Admixture concrete	8156	710	32.90
Self compacting Concrete	8043	841	37.40
Self-curing concrete	7860	766	34.07

3.2Tensile strength of specimens: Tensile strength tests were car- ried out on cubes of 150 mm size on a compressive testing machine of 2000 kN capacity as per IS516:1959.

Fig 2. Test setup for tensile strength of concrete cubes

types of spec- imen

Weight of specimen in kg

Ultimate load in kN

Average tensile strength N/mm2

Conventional concrete

8181

140

6.21

Admixture

concrete

8254

145

6.45

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3.3The modules of elasticity of concrete: compression

rests were carried out on cylinders of 150mm diameter and 300mm 15
height on a testing machine of 2000 kN capacity as per IS516:1959.

CB AC SCC SCU

0 0.2 0.4 0.6 0.8

Fig 4. Load deflection behaviour under compression

4.Test procedure:

Flexure strength tests were carried out on beams of size
125×250×1000mm on loading frame of capacity 500kN. All the beams were tested under centre single point load Condition. The beams are tested as simply supported beam. The beam designed as a under reinforced beam having 3 numbers of 12mm dia bar used as a

Fig 3 . Test set up for load deflection behaviour under compres-

sion

Table 3. Comparison of experimental value with IS code value for E for concrete

tension reinforcement and 2 numbers of 10mm dia bar used as a compression reinforcement. Two legged 8mm stirrups used as a shear reinforcement spacing of 170mm c/c. The deflectometer was set the bottom of the beam. Proving ring as placed the beam. While the load was applied from hydraulic jack the deflectometer in the proving ring indicates the load applied on the beam as shown as fig.

Fig. 5. Static load set up for beams

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Fig 6. load deflection Behaviour for all Beams

Table 4 Test results

IJSER

O 70

D 60

N 50

K 40

CB AC SCC SCU

0 1 2 3

DEFLECTION IN 'mm'

Fig 7. Failure Of All Specimens

Mode of failure: Figure 7 shows the cracking pattern of self com- pacting concrete beam (SCC), admixtures beam, self curing concrete beams, and conventional beam subjected to flexural load until fail- ure. During early stages of loading, fine vertical flexural crack ap- peared around the mid span of beams, as expected. With the increase in load, flexural cracks formed. With further increase in load, the flexural cracks started to propagate diagonally towards the loading point and other new diagonal cracks began to form separately in other locations. In general, SCC beams had slightly lower number of cracks than those other beams.

Discussion: The yield load and yield deflection for self compacting concrete beams was increased by 50% and 35%when compared with control beams. The ultimate load and ultimate deflection for self compacting concrete beams was increased by 36%and32.65%when compared with the control beams. The ultimate load for admixture concrete beams and self curing concrete beams was increased by

27.27%and 30.43% when compared with control beams. The ulti- mate deflection for admixture concrete beams and self curing con-

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crete beams was increased by 14.5% and 7.82% when compared with control beams.
The deflection ductility for self compacting concrete beams was
flection ductility for admixture. concrete beams and self curing con- crete beams was increased by 20.51% and 40.60% when compared with control beams. Based on the experimental results it was found that self compacting concrete beams shows better results.

Comparision of Ultimate

Load

150000

100000

An artificial neural network is an artificial intelligence technique. It is a simulation of human brain –like architecture. An artificial neural network is a massively distributed processor made up of interconnec- tion of simple processing elements i.e. neurons outputs are connect- ed, through weights, to all other neurons including themselves. Arti- ficial neural networks are simply a class of mathematical algorithms, since a network can be regarded essentially as a graphic notation for

50000

Experimental

ANN

the biological neural networks found in living organisms. Artificial

that are able to acquire, store and utilize the experiential knowledge that has been related to network capabilities and performance.

Comparision of Ultimate

Deflection

Comparision of Yield Load

2.5

80000

60000

1.5

0.5

Experimental

ANN

0.8

0.6

0.4

0.2

Comparision of Yield

Deflection

Experimental

ANN

Comparision of Deflection

Ductility

2 Experimental

0 ANN

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6. Conclusion:

SCC was designed and 12mixes with various replacements of con- stituent materials and addition of mineral and chemical admixtures were cast and tested. The self compatibility properties were tested in the fresh state and satisfied the SCC criteria. The experimental re- sults were compared with predicted values through ANN.
For the hardened properties the SCC were derived.
1. Compressive strength of self compacting concrete was increased
12.86% with comparing conventional concrete.
2. Tensile strength of self compacting concrete was increased 9.82 %
with comparing conventional concrete.
3. Compressive strength of self curing concrete and admixture was increased 8.9% and 12.03% with comparing conventional concrete.
4. Flexural capacity of self compacting concrete beams show better results.
5. The ultimate load and ultimate deflection for self compacting con- crete beam was increased 36% and 32.65% when compared control beams.
6. The predicted results ANN compared with the experimental results were quite satisfactory.
8. The percentage errors of predicted values through ANN when compared with the experimental results varies between 0.8% to
16.60%

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