Experimental Investigation on Effect of Fire on Properties of Concrete with the Use of Admixture

IJSRD - International Journal for Scientific Research & Development| Vol. 3, Issue 08, 2015 | ISSN (online): 2321-0613

Experimental Investigation on Effect of Fire on Properties of Concrete with the use of Admixture 1

Ruchita Bawankar1 V.D. Vaidya2 Valsson Varghese3 M.Tech. Scholar 2Assistant Professor 3Professor & HOD 1,2,3 Department of Civil Engineering 1,2,3 K. D. K. College of Engineering, Nagpur, India

Abstract—Damage due to fire can cause in terms of loss of life, homes and livelihoods. One of the advantages of concrete over other building materials is its inherent fireresistive properties. However, concrete structures must still be designed for fire effects. Structural components must still be able to withstand dead & imposed loads without collapse even though the rise in temperature causes a decrease in the strength & modulus of elasticity for concrete. Fire resistance is measured in terms of structural stability, structural integrity and insulation. This Experimentation involve the study of residual strength in concrete after exposure to elevated temperatures for concrete in which coarse aggregate replace with (20%, 40% and 60%) blast furnace slag and additional 1% steel fiber is added to increase the tensile strength of concrete. The effect of elevated temperature at 200, 400, 600, 800, 1000 and 1200 for the exposure of 1hours are studied. Compressive strength, split tensile strength and flexural strength are obtained after exposure to elevated temperature. Also investigated colour change, area of colour spot, width of crack, types of crack, of samples when exposed to fire at different temperatures and exposure times.

Key words: Blast Furnace Slag, Steel Fiber, Elevated Temperature

use of various fuel types for open-flame cooking, lighting and heating in buildings. Fire-safety education and law and order can be the major factors in reducing the causes of fires.

Concrete is composite material that consists mainly of mineral aggregate bound by a matrix of hydrated cement paste. A matrix is highly porous and contains a relatively large amount of free water unless artificially dried. When expose to high temperature, concrete undergoes change in its chemical composition, physical structure and water content. This change occurs primarily in the hardened cement paste in unsealed condition. Such changes are reflected by changes in the physical and mechanical properties of concrete that are associated with temperature increases. Deterioration of concrete at high temperature may appear in two forms:  Local damage (cracks) in the material itself.  Global damage resulting in the failure of the elements.

I. INTRODUCTION Any engineering advancement is for betterment of human life. Shelter is considered as one of the basic needs for human beings. The buildings constructed should give protection from heat, cold, rain, and also from disasters like fire, floods and earthquakes. Fire is considered as one of the disastrous event which causes loss or damage to human life and property. When there is an accidental fire in a structure, the duration of fire will be less but the intensity of heat produced will be more, this heat causes damage to the structures. In addition to accidental fire there are some special structures which are subjected to high temperatures, like take-off areas of jet aircraft, rocket launching pads, nuclear reactors, chimneys, metallurgical or chemical industries, glass, cement industry, coke ovens, storage tanks for hot crude oil and hot water, where the localized areas of concrete are subjected to high temperatures, The material used for construction should be capable Of resisting high temperatures and it should also give minimum time for the inmates to escape.

The rapid growth of modern cities inspired much Speculative building and the structures usually were built close to one another because of the disorganized manner in which construction was proceeding. As more and more people congregate closer and closer together in settlements as urbanization increases, risks associated with fire increase.

If there, fire will be occur; it is difficult to save life of residents live in such places. Fire in human settlements is caused predominantly accidentally, usually in relation to the

Fig. 1: Surface cracking after subjected to high temperatures.

Fig. 2: Structural Failure A. Steel Fibre Cementitious matrices such as concrete have low tensile strength as concrete have low tensile strength and fail in brittle manner. Adding short needle like fiber to such matrices enhances their mechanical properties particularly their toughness, durability and energy absorbing capacity under impact.

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Experimental Investigation on Effect of Fire on Properties of Concrete with the use of Admixture (IJSRD/Vol. 3/Issue 08/2015/146)

II. LABORATORY TESTING A. Physical Properties of Cement

Fig. 3: Steel Fibre added in Concrete 1) Advantages and Benefits of Fibres in Concrete:  Fibres inhibit and controls the formation of intrinsic cracking in concrete caused both in the plastic and hardened stage of concrete, thus ensuring a more durable concrete construction.  Fibres reinforce concrete against impact forces, thereby improving the toughness characteristics of hardened concrete.  Fibres improve the resistance to shattering forces caused due to earthquake loads and vibrations induced in machine foundations, thus making concrete a more versatile material for such critical applications.  Fibres enhance the hardness of the surface of concrete against material loss due to abrading forces caused by frequent movement of wheel loads. This enhances the service life and safety of concrete pavements.  Fibres reduce the permeability and water migration in concrete, which ensures protection of concrete due to the ill effects of moisture.  Fibres reduce plastic shrinkage and settlement cracking when concrete is still green, thus enhancing the overall life of the structure and reducing the maintenance cost.  Fibres can replace the secondary reinforcement or crack control steel used in grade slabs, thereby reducing the overall cost of the structure.

B. Blast Furnace Slag Throughout the world there is an increasing focus on the need to recycle and to more fully utilise co-products of manufacturing processes in an attempt to conserve our finite natural resources. Technical evaluation supported by field experience has shown that co-products such as blast furnace slag have, in many applications, properties suitable to replace or supplement and improve traditional materials used.

Table 1: Physical Properties of Cement B. Physical Properties of Fine Aggregates

Table 2: Physical Properties of Fine Aggregates C. Physical Properties of Coarse Aggregates (mm)

Table 3: Physical Properties of Coarse Aggregates (mm) D. Physical Properties of Steel Fibre

Table 4: Physical Properties of Steel Fibre E. Physical Properties of BFS Fig. 4: Blast Furnace Slag 1) Benefit of Blast Furnace Slag Use in Concrete  Environmentally friendly energy by product  Enhances concrete durability  Continued strength gain  Reduces heat in concrete  Early age plastic and hardened concrete property.

Table 5: Physical Properties of BFS

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Experimental Investigation on Effect of Fire on Properties of Concrete with the use of Admixture (IJSRD/Vol. 3/Issue 08/2015/146)

F. Chemical Properties of BFS

B. Compressive Strength (N/mm2)

Table 9: Compressive Strength (N/mm2) Table 6: Chemical Properties of BFS G. Adapted Mix Design

Table 7: Adapted Mix Design III. FURNACE SPECIFICATIONS The electric furnace is used to heat the specimens. The maximum temperature attained in this furnace is 1000°C. There are mainly three components of furnace are as follows,  Furnace Door  Connection Box  Heating Coils

Fig. 6: Compressive Strength (N/mm2) C. Split Tensile Strength (N/mm2)

Table 10: Split Tensile Strength (N/mm2)

Fig. 7: Split Tensile Strength (N/mm2) Fig. 5: Rectangular Type Electric Heating Furnace.

D. Flexural Strength (N/mm2)

IV. HARDENED CONCRETE TEST A. Testing Report of Conventional Concrete

Table 11: Flexural Strength (N/mm2)

Table 8: Testing Report of Conventional Concrete

Fig. 8: Flexural Strength (N/mm2)

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Experimental Investigation on Effect of Fire on Properties of Concrete with the use of Admixture (IJSRD/Vol. 3/Issue 08/2015/146)

V. CONCLUSION  

        

Based on the limited experimental work carried out in this particular study, The Following conclusions may be drawn out, After elevated temperatures test and analysis it was found that with the increasing temperature the compressive strength, tensile strength and flexural strength of concrete gets reduced.

As temperature and exposure time increases the effect of fire on concrete increases.

Effect of fire can be observed on the surface of concrete in the form of deep cracks.

Between 400-600°C temperature Strength loss starts.

Above 6000C temperature concrete is not functioning at its full structural Capacity.

At elevated temperature the concrete becomes more & more brittle and the loss of strength is more than 30%.

At 600°C temperature whitish colour and at 800°C temperature dark brown colour appears on the surface of cubes.

At 1000°C temperature hair cracks developed on specimen.

At 1200°C temperature blast furnace slag in concrete started to melt, so it gives negligible strength.

At elevated temperature BS1 (20%blast furnace slag +1% steel fibre) found suitable combination.

REFERENCES

[1] Rafat Siddique, Deepinder Kaur “Properties of concrete containing ground granulated blast furnace slag (GGBFS) at elevated temperatures”. Journal of Advanced Research (2012) 3, 45–51Civil Engineering Department, Thapar University, Patiala, Punjab 147004, India Received 21 July 2010; revised 16 December 2010; accepted 7 March 2011 [2] Alaa A. Bashandy “Influence of Elevated Temperatures on the Behavior of Economical Reactive Powder Concrete” Journal of Civil Engineering Research 2013, Civil Engineering Department, Faculty of Engineering, Menoufiya University, Egypt [3] B G Buddhdev, Dr. H R Varia “Feasibility Study on Application of Blast Furnace Slag in Pavement Concrete” IJIRSET (An ISO 3297: 2007 Certified Organization) Vol. 3, Issue 3, March 2014 [4] P. Jyotsna Devi, Dr. K. Srinivasa Rao “A Study on the Flexural and Split Tensile Strengths of Steel Fibre Reinforced Concrete at High Temperatures” Dept. of Civil Engg. Andhra University, Visakhapatnam, AP, India IJEAR Vol. 4, Issue Spl-2, Jan - June 2014 [5] Khaled Mohammed Nassar Prof. Samir “Improving Fire Resistance of Reinforced Concrete Columns” Islamic University of Gaza Higher Education Deanship Faculty of Engineering Civil Engineering Department Design and Rehabilitation of Structures 2011 [6] Concrete Technology by M. S. Shetty.

[7] IS: 1641-1988 (Code of Practice for Fire Safety of Building (General): General Principles of Fire Grading and Classification)

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