Analysis of Compressive Strength of High Grade Glass Fibre Reinforced Self-Compacting Concrete

Analysis of Compressive Strength of High Grade Glass Fibre Reinforced Self-Compacting Concrete

Ujjwal goel1, Anjali Malik2

1,2 Puran Murti College of Engineering, Kamiaffiliated to DCRUST, Murthal Sonepat, India

Abstract A self-compacting concrete (SCC) is the one that can be placed in the form and can go through obstructions by its own weight and without the need of vibration. In this work an attempt has been made to analyse the compressive strength of Glass fibre SelfCompacting Concrete under confined and unconfined states with different percentages of confinement (in the form of hoops). Since the confinement provided by lateral circular-hoop reinforcement, is a reaction to the lateral expansion of concrete,

lateral reinforcement becomes effective only after considerable deformation in the axial direction.

Keywords Glass fibre, Reinforced self-compacting contrete, Admixtures, Compressive strength analysis.

1. INTRODUCTION

   Concrete is a vital ingredient in infrastructure development with its versatile and extensive application. It is the most widely used construction material because of its mouldability into required structural form and shape due to its fluid behavior at early ages. However thorough compaction, using vibration, generally essential for achieving the required strength and durability of concrete. Inadequate compaction of concrete results in large number of voids affecting performance of structures. Self compacting concrete provide solution to these problems. SCC is a recently developed concept in which the ingredients of the concrete mix are proportioned in such a way that it can flow under its own weight to completely fill the formwork and passes through the congested reinforcement without segregation and self consolidate without any mechanical vibration. In this work a attempt has been made to analyse the compressive strength of glass fibre self compacting concrete under confined and unconfined states with different percentage of confinements.

2. MATERIALS USED

1. Cement

   Ordinary Portland cement of 53 grade available in local market is used in the investigation. The Cement used has been tested for various proportions as per IS 4031- 1988 and found to be confirming to various specifications as per IS 12269-1987.The specific gravity was 3.03 and fineness was 2800cm2/gm.

   Physical properties of cement

   Chemical composition of cement

2. Fine aggregate

   River sand was used as fine aggregate is natural and obtained from local market. The physical properties like specific Gravity, bulk density, gradation fineness modulus are tested in accordance with IS 2386.

3. Coarse aggregate

   The crushed angular granite metal of coarse aggregate of 20 mm maximum size as well as 12mm size are obtained from the local crushing plant, is used in the present study. The physical properties of the coarse aggregate like specific gravity, bulk density, gradation fineness modulus are tested in accordance with IS 2386.

4. Fly ash

   In the present investigation work, Type-II fly ash was used as cement replacement material. The specific surface area of fly ash is found to be 484.20 m2/N by Blanes Apparatus. The properties of fly ash are confirming to I.S. 3812 -1981of Indian Standard Specification for Fly Ash for use as Pozzolana and admixture. & IS 456-2000 can be used to produce good quality concrete. Typical characteristics of good quality fly ash are as follows:

   • Fineness (Blaines): 48.42 m2/N (Min.)

   • Lime Reactivity: 4.5 N/mm2 (Min.)

   • Loss on ignition: 5% (Max.)

5. Chemical admixtures

   Super plasticizer (Glenium -B233) (With base material Poly Corboxylic Eather)

6. Viscosity modifying agent

   A Viscosity modified admixture for Glenium -2 (With base material Poly Corboxylic Eather) which is free flowing liquid Chloride Content was used as Viscosity Modifying Agent.

7. Glass fibres

   The glass fibres are of Cem-FIL Anti Crack HD (High Dispersion) Glass Fibres with Modulus of Elasticity 72 GPa, Filament Diameter 14 Microns, Specific Gravity 2.68, Filament length 12mm and having Aspect Ratio of 857: 1. The number of fibres per 1 kg is 212 million fibres.

   1. MODELS OF SPECIMENS

      Fig 1: Cylinder without confinement

      1. 0.798% confinement

      2. 1.062% confinement

         Properties of selected glass fibres

8. Water

   Confirming to IS 456-2000.

   III. MIX PROPORTIONS

   M50 grade SCC mix was designed based on Indian Standard Recommended Method of Concrete Mix Design (IS 10262-1982), and was further modified by fine tuning the relative proportions of fine and coarse aggregate, filler material like fly ash, glass fiber along with super plasticizers and viscosity modifying agents.

   1. 1.327% confinement

   2. 1.591% confinement

      Fig 2: Cylinder with confinement

      Steel as a confining material is used in Concrete and the properties of concrete was studied. The concrete bond strength should be sufficient to prevent bond failure. The effectiveness of bond is affected by the position of the embedded bars and the quality of concrete as cast. An adequate concrete cover is necessary in order to properly transfer bond stresses between steel and concrete. The main reasons for taking steel as a reinforcing material is:

      • its thermal coefficient of expansion is similar to that of concrete.

      • it develops good bond with concrete.

      • it is cheaply and easily available in the market.

      • it is economical comparing to all the aspects.

1. COMPRESSIVE STRENGTH

   In the present investigation the size of 100 x 100 x 100 mm are used. In the compressive test, the cube while cleaned to wipe of the surface water, is placed with the cast faces in contact with the planes of the testing machine, i.e. the position of the cube then tested is at right angles to that as cast.

   The specimens were removed from the moulds and submerged in clean fresh water until just prior to testing. The temperature of water in which the cylinders were submerged was maintained at 27o C+2o C and 90% relative humidity for 24 hours. The specimens were cured for 28 days.

2. RESULTS AND DISCUSSIONS

   The compressive strength values obtained by testing standard Cylinders of GFRSCC with and without confinement are tabulated in tables

   Compressive strength of cylinders tested at UTM

   Compressive strength of cubes tested under compression testing machine

   All the specimens with confinement have shown strength above 50 MPa, which is the required strength. The mix, with and without confinement, containing the mineral admixture of Fly ash (33%) has shown higher compressive strength compared to other SCC mixes. Further the GFRSCC with confinement compared to Plain GFSCC has shown an improvement in compressive strength by 7.52% to 44.30%.

3. CONCLUSION

IT HAS BEEN VERIFIED, BY USING THE SLUMP

FLOW AND U-tube tests, that selfcompacting concrete (SCC) achieved consistency and self-compactability under its own weight, without any external vibration or compaction. Also, because of the special admixtures used, SCC has achieved a density between 2400 and 2500 kg/m³, which was greater than that of normal concrete, 2370-2321 kg/m³.

Self-compacting concrete can be obtained in such a way, by adding chemical and mineral admixtures, so that its compressive strengths are higherthan those of normal vibrated concrete. An average increase in compressive strength of 60% has been obtained for SCC.

REFERENCES

1. Efnarc, specifications and guidelines for self-compacting concrete, efnarc, uk (www.efnarc.org), february 2002, pp. 1-32.

2. Kumar p., haq m. Ajazul and kaushik, s.k. (2004). Early age strength of scc with large volumes of fly ash, indian concrete journal, vol. 78, no. 6, p 25-29.

3. Limitations, concrete international, vol. 5, no. 51, pp.40-46 (1983).

4. Indian standard code is: 2386, method of test for aggregates for concrete, reprinted 1997.

5. Indian standard code is:383, method of sampling of aggregates for concrete.

6. Is: 5161956 (reaffirmed 1999), indian standard methods of tests for strength of concrete.

7. Efnarc guidelines for viscosity modifying agents.

8. Indian code of practice for plain & reinforced concrete is 456- 2000.

9. Indian code of practice for steel is 800-1984.

10. Subramanian s, chattopadyaya d. Experiments for mix proportioning of self-

11. Compacting concrete, indian concrete journal, january 2002,pp 13-20.

12. M.s.shetty, concrete technology, s.chand company ltd-2005,pp

    :573-576.

13. Softwares used : ms excel