Comparative Study of Crushing Strength of Conventional and Self Compacting Concrete

Download Full-Text PDF Cite this Publication

Text Only Version

Comparative Study of Crushing Strength of Conventional and Self Compacting Concrete

Mitesh Patel

M Tech Scholar

Pacific University Udaipur Rajasthan

Abstract- This paper deals with comparison of self compacting concrete with conventional concrete. Various parametric tests were performed on samples prepared using both types of concrete. It was observed that the self compacting concrete has higher crushing strength than conventional concrete.

  1. INTRODUCTION

    Self-compacting concrete (SCC) can be described as a concrete which has the ability to compact itself only by means of its own self weight without the requirement of any type of vibrations. Self-compacting concrete can be also known as Self Consolidating Concrete or Self Leveling Concrete. Self compacting concrete is placed or poured in the same or the usual way as ordinary/normal concrete but the fact is without vibration. It comes in a form of a very fluid and can pass around obstructions and can automatically fill all the nooks and corners without any risk of either mortar or other ingredients of concrete without separation, at the same time there are no problems of appearing entrapped air or rock pockets. The result which we get from the surface finishing which is produced by self- compacting concrete is exceptionally good and there will no requirement of patching.

    Fig. 1. Nature of self compacting concrete

    Tanuj Uppal Assistant Professor

    Pacific University Udaipur Rajasthan

    Fig. 2 Comparison between SCC and conventional concrete

    SCC is characterized by a low yield stress, high deformability and moderate viscosity necessary to ensure uniform suspension of solid particles during transportation, placement (without external compaction), and thereafter until the concrete sets. Such concrete can be used for casting heavily reinforced sections, places where there can be no access to vibrators for compaction and in complex shapes of formwork which may otherwise be impossible to cast, giving a far superior surface than conventional concrete.

  2. METHODOLOGY

    The procedure for preparation of cube of concrete (M-25) is as follows:

    • Intial step in mould preparation is fixing and oiling

    • Then ensure that proper shape is there in mould or not

    • Preparation of concrete mixture in sufficient quantity to fill the cubical moulds

    • Filling and Compaction in 3 Equal layers with minimum of 35 strokes

    • Identification and marking of respective cube samples for tests

    • Removal of cube samples from mould with utmost care to ensure that no damage is done to the sample

    • Carrying and displacing cube samples must be done with proper care

      Fig. 3. Cube preparation

      Various steps that are involved in the study was:

      • Preparation phase

        • Preparation of conventional concrete mixture

        • Preparation of conventional concrete cube (M25)

        • Preparation of Self compacting concrete mixture

        • Preparation of Self compacting concrete cube (M25)

      • Testing phase

        • Slump flow test, L box apparatus test and J ring flow test were performed for all above types of mixtures

        • Compression tests were performed mainly using compression test machine on conventional concrete, Self compacting concrete and fiber reinforced concrete.

      • Analysis Phase

        • Crushing strength and crushing load of all type of samples were noted and calculated.

      • Reading were repeated to achieve repeatability of results

      • Crushing strength of self compacting concrete was compared to the crushing strength of conventional concrete

  3. RESULTS AND DISCUSSION

    Self compacting concrete and conventional concrete mixtures were used for preparing cube samples of same size (M25). Prepared cubes were subjected to compression tests under compression testing machine after weighing. Compression tests of prepared samples were carried out after 7 days, 14 days and 28 days respectively. It was a

    known fact that initial crushing strength was observed after 7 days while crushing attains its maximum and true value after 28 days due to proper setting of core structure and water.

    TABLE.I Cube Testing Results of Normal Concrete (7 Days) Grade of Concrete= M25

    Cube I.D

    Weight of Cube

    Crushing Load (kN)

    Compressive Strength (N/mm2)

    Average Compressive Strength

    NC-1

    8.740

    451

    20.04

    19.98(N/mm2)

    NC-1

    8.615

    422

    18.75

    NC-1

    8.518

    476

    21.15

    TABLE.II Cube Testing Results of Normal Concrete (14 Days) Grade of Concrete= M25

    Cube I.D

    Weight of Cube

    Crushing Load (kN)

    Compressive Strength (N/mm2)

    Average Compressive Strength

    NC-2

    8.580

    595

    26.44

    25.7(N/mm2)

    NC-2

    8.600

    599

    26.22

    NC-2

    8.720

    550

    24.44

    TABLE .III Cube Testing Results of Normal Concrete (28 Days) Grade of Concrete= M25

    Cube I.D

    Weight of Cube

    Crushing Load (kN)

    Compressive Strength (N/mm2)

    Average Compressive Strength

    NC-3

    8.455

    723

    32.13

    31.12(N/mm2)

    NC-3

    8.560

    628

    27.91

    NC-3

    8.495

    750

    33.33

    Self compacting concrete mixture was prepared and then poured into the constructed cubical mould in order to attain a cube of M25 grade since the cube was made based on ASTM standard all the dimension of the cube was known. Known dimensions were basically useful for calculating the area and volume of concrete cube. Various cube samples were prepared and cured. Samples were tested under compressive loads after 7, 14 and 28 days respectively. It can be observed from the below tables that with the increase in number of days crushing strength and crushing load carrying capacity of the structure continues to increase and attains maximum value after 28 days.

    TABLE.IV Cube Testing Results of Self Compacting Concrete (7 Days) Grade of Concrete= M25

    Cube I.D

    Weight

    of Cube

    Crushing

    Load (kN)

    Compressive

    Strength (N/mm2)

    Average

    Compressive Strength

    SCC-1

    8.590

    517

    22.97

    22.33(N/mm2)

    SCC-1

    8.660

    502

    22.31

    SCC-1

    8.725

    489

    21.73

    TABLE.V Cube Testing Results of Self Compacting Concrete (14 Days) Grade of Concrete= M25

    Cube I.D

    Weight of Cube

    Crushing Load (kN)

    Compressive Strength (N/mm2)

    Average Compressive Strength

    SCC-2

    8.710

    603

    26.8

    26.97(N/mm2)

    SCC-2

    8.690

    591

    26.26

    SCC-2

    8.645

    627

    27.86

    TABLE .VI Cube Testing Results of Normal Concrete (28 Days) Grade of Concrete= M25

    Cube I.D

    Weight of Cube

    Crushing Load (kN)

    Compressive Strength (N/mm2)

    Average Compressive Strength

    SCC-3

    8.510

    785

    34.88

    36.39(N/mm2)

    SCC-3

    8.740

    843

    37.46

    SCC-3

    8.645

    829

    36.84

    Conventional concrete and Self compacting concrete were compared to each other on the basis of crushing strength and crushing load carrying capacity. It was observed that fiber reinforced concrete has more crushing load than conventional concrete for same weight samples under all categories i.e. after 7 days curing, 14 days curing and 28 days curing respectively. It was also observed that mean compressive strength of fiber reinforced concrete was higher than that of conventional concrete.

    Crushing load (kN)

    600

    615

    Concrete

    610

    605

    600

    595

    590

    585

    580

    575

    8.71

    8.69

    8.645

    Approximate Weight (Kg)

    900

    800

    700

    600

    500

    Crushing Load (kN)

    Fig 5 Crushing load vs Weight of cube cured for 14 days

    500

    Crushing Load (kN)

    400

    300

    200

    8.51 8.74 8.645

    Approximate Weight (Kg)

    100

    CONCRETE

    400

    300

    200

    Concrete

    100

    0

    Self

    compacting concrete

    0

    8.59 8.66 8.725

    Approximate Wieght (kg)

    Fig 6 Crushing load vs Weight of cube cured for 28 days

    Fig 4 Crushing load vs Weight of cube cured for 7 days

    Concrete

    7

    14

    Number of days cured

    28

    30

    25

    20

    15

    10

    5

    0

    40

    35

    Compressive strength (N/mm2)

    Fig. 7 Comparison of compressive strength of concrete and Self compacting concrete

    It can be seen from the diagram below that self compacting concrete has higher strength on comparison with conventional concrete. It was observed that Self compacting concrete has 16.9% higher compressive strength on comparison with concrete.

  4. CONCLUSIONS

Some of the major observations of the study are:

  • Conventional concrete and self compacting concrete mixtures were prepared.

  • Compression test cubes for conventional concrete and self compaction concrete were prepared.

  • Slump test, L box apparatus test and J ring test for both types of concrete mixture were performed.

  • Self compacting concrete has higher crushing load than conventional concrete for all types of cured cube test

i.e. 7 days cured cube, 14 days cured cube and 28 days cured cube respectively.

REFERENCES

  1. Y. Xie, B. Liu, J. Yin, S. Zhou, Optimum mix parameters of high- strength self compacting concrete with ultra-pulverized fly ash, Cem. Concr. Res. 32 (3) (2002) 477480.

  2. K. Ozawa, K. Maekawa, H. Okamura, Development of the high performance concrete, Proc. Jpn. Concr. Inst. 11 (1) (1989) 699 704.

  3. J. Fernandez-Gomez, G.A. Landsberger, Evaluation of shrinkage prediction models for self-consolidating concrete, ACI Mater. J. 104 (5) (2007) 464473.

  4. W. Zhu, J.C. Gibbs, Use of different limestone and chalk powders in self compacting concrete, Cem. Concr. Res. 35 (8) (2005) 14571462.

  5. G. Heirman, L. Vandewalle, D.V. Gemert, V. Boel, K. Audenaert, G. De Schutter, et al, Time-dependent deformations of limestone powder type self-compacting concrete, Eng. Struct. 30 (10) (2008) 2945 2956.

  6. B. Felekoglu, Utilisation of high volumes of limestone quarry wastes in concrete industry (self-compacting concrete case), Resour. Conserv. Recycl. 51 (4) (2007) 770791.

Leave a Reply

Your email address will not be published. Required fields are marked *