Effect Of Elevated Temperature On Mechanical Properties Of High Strength Self Compacting Concrete

Effect Of Elevated Temperature On Mechanical Properties Of High Strength Self Compacting Concrete

ISSN: 2278-0181

Vol. 1 Issue 8, October – 2012

By

1. VASUSMITHA* Dr.P.Srinivasa Rao **

   *Research Scholar, J.N.T.U. College of Engineering. Hyderabad, A.P. India.

   **Professor and Head, Dept of Civil Engineering, J.N.T.U. College of Engineering. Hyderabad, A.P. India

   ABSTRACT – High-strength concrete is a material often used in the construction of high rise buildings. In the case of unexpected fire, the building concrete elements such as columns, slab and walls will be subjected to extreme temperatures. In order to assess the performance of high-rise concrete members it is important to understand the changes in the concrete properties due to extreme temperature exposure. The elimination of vibration for compacting concrete during placing through the use of Self compacting concrete leads to substantial advantages related to better Homogeneity, Enhancement of working environment and improvement in the productivity by increasing the speed of construction.

   This paper mainly concentrates on studying mechanical properties High Strength Self Compacting concrete subjected to Elevated Temperature of 200, 400 and 600oC with exposure duration of 4,8,12 Hours of Grade M80 Mix. The resulting concrete is characterized in the fresh state by methods used for Self compacted concrete, such as Slump flow, V-funnel and L-Box tests respectively

   Key words: High Strength concrete, Self compacting Concrete, Quartz powder , Quartz sand , Crushed basalt, Split tensile strength, Pulse velocity, Compressive strength.

   1. INTRODUCTION

      Concrete is a material often used in the construction of high rise buildings and in case of unexpected fire, the concrete properties are changes after fire. Hence, it is important to understand the change in the concrete properties due to extreme temperature exposures. As the concrete used for special purpose, the risk of exposing it to high temperature also increases. To be able to predict the response of structure after exposure to high temperature, it is essential that the strength properties of concrete subjected to high temperatures be clearly understood. High temperature can cause the development of cracks. These cracks like any other cracks propagation may eventually cause loss of structural integrity and shorting of service life. The influence of elevated temperatures on mechanical properties of concrete is of very much important for fire resistance studies and also for understanding the behavior of containment vessels, chimneys, nuclear reactor pressure vessels during service and ultimate conditions structures like storage tanks for crude oil, hot water , coal gasification, liquefaction vessels used in petrochemical industries, foundation for blast furnace and coke

      industries, furnace walls industrial chimney, air craft runway etc., will be subjected to elevated temperatures. So that the variation of compressive strength, performance are some of the important parameters to be investigated when concrete structures are subjected to temperatures.

      Self Compacting Concrete is defined as a category of high performance concrete that has excellent deformability in the fresh state and high resistance to segregation, and can be placed and compacted under its self weight without applying vibration.

   2. LITERATURE REVIEW

      Effect of transient high temperature of high strength concrete by Castillo, C and Durrant AJ (1990) (1) Castillo.C et. al carried out investigations to study the effect of transient high temperature on compressive strength and load deformation properties of high strength concrete under both in loaded and pre loaded conditions and to compare the behavior with that of normal strength concrete. Based on the results obtained on this study, it was concluded that when exposed to temperature in the range of 100o C to 300o C, high strength concrete showed a 15 to 20 % loss of compressive strength. After an initial loss of strength, the HSC recover its strength between 300oC to 400oC reaching a maximum value of 8 to 13 % above the room temperature.

      Elevated temperature effects on high residual strength by George C. Hoff et al (2000) (2) George C. Hoff et al conducted research to study the effect of elevated temperature on residual strength of High Strength Concrete. Twelve HSC concrete mixtures were made including three types of concrete: normal density (MND) concrete where 45 % by volume of the coarse aggregate was structural light weight aggregate with the remaining 55 % by volume being normal weight aggregate and two types aggregate were used. Each concrete made with a specific type of aggregate was made with and without the incorporation of polypropylene fibers. It was concluded that in residual strength at 200o C exposure when subjected to 100oC exposure. At constant temperatures of 300o C there is a significant loss of strength. Residual strengths of HSC at exposed temperatures of 300oC or higher are significantly different than residual strength for NSC.

      Mechanical properties of PENLY reactor envelope at temperatures up to 200o C by Janotka, Nurnbergurora T (1990), Thermo (3) Janotka, et al carried out experimental investigation to study the effects of high temperatures of up to 200o C on the phase composition, pore structure development and

      physico-mechanical properties of concrete at the PENLY nuclear plant in France. It was reported that the decrease in mechanical properties of the specimens and shrinkage / expansion development of PENLY concrete was influenced by the degradation through changes induced in basic processes of cement hydration at achieved temperature levels. The damage of bound water from hydration air voids evoking pore structure coarsening.

      Effects of test Conditions and Mixture proportions on Behavior of High Strength concrete Exposed to High Temperatures by Long T.Phan and Nicholas Carino J. (2002) (4) : Mechanical properties of high strength concrete exposed to elevated temperatures were measured by heating 100x200mm cylinders at 500 C / min to temperature up to 6000 C. Heating was carried out with and without a sustained stress, and properties were measured at elevated temperatures as well as after cooling to room temperature. Four mixtures with water-cementitioius materials and compressive strength ranging from 51 to 98 MPa were used. Two of the mixtures contained silica fume. The values of w/cm or the presence of silica fume affected the results. The influence of these variables on the tendency for explosive spelling was also examined by the authors. Results indicate that losses in relative strength due to high temperature exposure were affected by the test condition and w/cm, but there were significant interactions among the main factors that resulted in complex behaviors. The presence of silica fume does not appear to have a significant effect. Measurements of temperature histories in the cylinders revealed complex behaviors that are believed to be linked to heat-induced transformations and transport of free and chemically combined water.

      Effect of Elevated temperature on compressive strength on HSC made with OPC & PPC by Srinivasa Rao K., Potha Raju

      1. and Raju P.S.N. (2006) (5): The authors made an attempt to study the effects of elevated temperatures ranging from 500 C and 2500 C on the compressive strength of HSC made with both ordinary Portland cement (OPC) and Portland pozzolana cement (PPC). The residual compressive strengths were evaluated at different ages. The results showed that atlater ages HSC made with Portland pozzolana cement performed better by retaining more residual compressive strength compared to concrete made with ordinary Portland cement.

         Malhotra (1956), Zoldners (1960), Davis (1967), Abrams (1971),

         Faiyadh (1989), Khoury (1992), and Noumowe et. al. (1994) (6) had reported the effects of high temperature exposure on the properties of concrete. Several mechanisms have been identified for the deterioration of concrete due to high temperatures. These include decomposition of the calcium hydroxide into lime and water, expansion of lime on re-hydration, destruction of gel structure, phase transformation in some types of aggregate, and development of micro-cracks due to thermal incompatibility between cement paste matrix and aggregate phase. High strength concrete compared to medium strength concrete is more brittle; contains less water; and the solid particles are more compact. Hence, the effects of high temperature on high strength concrete will be different to those with the medium strength concrete.

         Sri Ravindrarajah et. al. (1998) (7) through their research concluded that the residual compressive and tensile strengths for high strength concrete with blended cement after heating to 800 C and water quenched were 31 % of its initial strengths whereas the corresponding residual strengths for concrete with ordinary Portland cement was 44%.

   3. EXPERIMENTAL PROGRAMME

      To study the Effect of Elevated Temperature on HighISSStNre:n2g27th8-0S1e8l1f Compacting Concrete and total No. of 30 CVuobl.e1s IossfueS8iz, eOc1to0b0erx- 2100102 mm and 30 Cylinder Specimens of size 100 x 200 mm were tested

      • The test specimens were subjected to temperatures ranging from 200 to 600 oC for exposure duration of 4,8,12 hours, their behavior was compared to that observed room temperature.

      • To study the Effect of Elevated Temperature on Compressive strength, Split Tensile Strength , Weight loss of Specimens and Pulse velocity to observe the crack pattern with respect to Room Temperature

      Materials Used

      1. Cement

         Ordinary Portland cement of 53 grades 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 of IS 12269-1987. The specific gravity was 3.15 and fineness was 2800 cm2/gm

      2. Coarse Aggregate

         Basalt originates from "hot spot" volcanoes, massive basalt flows and mid oceanic ridges. Basalt is a dark-colored, fine-grained, igneous rock composed mainly of plagioclase and pyroxene minerals. In present investigation Crushed basalt metal of Size 2 to 5 mm is used as Coarse Aggregate with Specific gravity of 3.10 and is obtained from local source.

      3. Quartz Powder and Quartz Sand

         Quartz has a hardness of 7 on Mohs scale and a density of 2.65 g/cm³. Quartz is a common constituent of granite, sandstone, limestone, and many other igneous, sedimentary, and metamorphic rocks. It has a hexagonal crystal structure and is made of trigonal crystallized silica. In present investigations the size of quartz sand is 0.3 to 0.8 mm and Quartz powder is in order of 0 -10 µm. Quartz sand is used a fine aggregate with Specific gravity of 2.65 and Quartz powder is used as a cementitioius material with Specific gravity of 2.63. These are obtained from local source.

      4. Viscosity Modifying Agent

         A Viscosity modified admixture for Rheodynamic Concrete which is colorless free flowing liquid and having Specific of gravity 1.01+0.01 @ 250C and pH value as 8+1 and Chloride Content nil was used as Viscosity Modifying Agent.

      5. Admixture

         The Modified Polycarboxylated Ether based Super Plasticizer which is Brown Color and free flowing liquid and having Relative density 1.08+0.01 and pH value greater than 6 and Chloride Content nil was used was Super Plasticizer. Flow tests were carried out on pastes containing different water to powder ratios or different superplasticizer dosages with a flow cone as in conventional self-compacting concrete. Superplasticizer dosage of about 1.8% was determined in powder mass as the optimum dosage to above Mix.

      6. Micro Silica

      Commercially available Micro silica from Elkem Metallurgy, India Ltd. Mumbai having Specific gravity of 2.1 is used. Micro Silica (very fine non-crystalline silicon dioxide) is a by-product of the

      manufacture of silicon, ferrosilicon or the like, from quartz and carbon in electric arc furnace. The Specific surface area was 20000 cm2/gm

   4. EXPERIMENTAL INVESTIGATION

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      Vol. 1 Issue 8, October – 2012

      A. Mix proportion

      As there is no standard procedure available for designing the mix proportions for Self Compacting Concrete proportion based on the Experimental trail was adopted. Water to cementitioius material by weight was kept at about 0.215 for M 80 grade of concrete. The Mix proportion for M80 grade SCC is reported in Table No.1

      Table 1.0: Quantities of Materials Required Per 1 Cum Of High Strength Self Compacting Concrete

      B.Preparation of specimen & Testing Procedure

      o

      For the temperatures of 200 C and above, an electrically heated

      muffle furnace designed for a maximum temperature of 1200 was used. The furnace was heated by means of exposed heating elements laid on the refractory walls of the inside chamber, which was approximately 400 by 400 by 800mm in dimension. The test specimens of size 100 x 100 mm cubes and 100 x 200 mm cylinders were stacked with sufficient space between two adjacent specimens to obtain a uniform heating in each specimen. The test specimens were heated in batches due to limited capacity of the furnace. Extreme care was taken when handling the heated concrete specimens. The test Setup, testing and Specimens after Impact test are shown in (Fig.1).

      Fig .1 Tested Specimens

      1. Tests on Fresh Concrete

         Conventional workability tests devised for conventionally vibrated concrete mixes are not adequate of SCC as they are not sensitive to detect all the characteristics of SCC mix. Many different methods have been developed to characterize the properties of SCC. As no single method has been found till date that characterizes all the relevant workability aspects, the mix was tested by more than one test method for the different workability parameters. The following test methods were used to characterize the workability properties of SCC for the final acceptance of the SCC mix proportion. Deformability and Viscosity of fresh concrete is evaluated through the measurement of slump flow time and diameter, L-Box ratio test and V-funnel flow time are shown (Fig.2)

      2. Slump Flow Test

         The slump flow test is used to assess the horizontal free flow and the filling ability of SCC in the absence of obstructions. It is recommended to maintain slump flow value as 650 to 800 mm.

      3. T 50cm Slump Flow Test

         This test is used along with slump flow test to assess the flowability of SCC.

      4. V-Funnel

         This test is used to determine the filling ability, flow-ability and segregation resistance of SCC

      5. L-Box

      This test assesses the flow of the concrete in presence of reinforcement obstructions.

      The summary of test results of workability parameters of High Strength Self compacting Concrete are reported in Table 2.0.

      Table No 2.0 Workability properties

      4200 at 12 hrs, for 4000C varied from 3900 to 4090 IaStS4N:pr2s7,83-0510801

      Vol. 1 Issue 8, October – 2012

      to 3800 at 8 hrs, 3290 to 3470 at 12 hrs, for 6000C at 4, 8, 12 hrs

      concrete specimen were crushed

      It is observed from Table No.7, that, Split Tensile strength of High Strength Self Compacting Concrete Specimens at 28 days at Room Temperature varied from 7.32 to 7.77, for 2000 C varied from 7.25

      o 7.48 at 4 hrs, 6.99 to 7.32 at 8 hrs, 6.87 to 7.08 at 12 hrs, for

      4000C varied from 6.81 to 6.99 at 4 hrs, 6.69 to 6.87 at 8 hrs, 6.24

      to 6.51 at 12 hrs, for 6000C at 4, 8, 12 hrs concrete specimen were crushed

      Fig .2 Workability Tests on High Strength Self Compacting Concrete

   5. RESULTS AND DISCUSSIONS

1. Workability

   As it is observed from Table No.2, the basic requirements of high flowability and segregation resistance as specified by guidelines on Self Compacting Concrete by EFNARC (8) are satisfied.

2. Effect of Temperature with respect to Exposure Time on High Strength self compacting concrete

The results of elevated temperature on HSSCC were provided in Tables from 3.0 to 10.0 and Fig. 3.0 to 10.0

It is observed from Table No.3, that, Compressive Strength of High Strength Self Compacting Concrete Specimens 28 days at Room Temperature varied from 84.69 to 82.57 N/mm2, for 2000 C varied from 80.59 to 76.62 at 4 hrs, 76.59 to 73.62 at 8 hrs, 74.55 to 71.68

at 12 hrs, for 4000C varied from 71.68 to 68.02 at 4 hrs, 67.02 to

66.02 at 8 hrs, 64.65 to 61.95 at 12 hrs, for 6000C at 4, 8, 12 hrs concrete specimen were crushed

It is observed from Table No.4, that, Percentage decrease in Compressive Strength of High Strength Self Compacting Concrete Specimens at 28 days with respect to Room Temperature for 2000 C varied from 4.84 to 7.21 at 4 hrs, 8.56 to 10.84 at 8 hrs, 11.97 to

13.19 at 12 hrs, for 4000C varied from 14.36 to 16.62 at 4 hrs, 17.86 to 19.04 at 8 hrs, 20.66 to 23.97 at 12 hrs, for 6000C at 4, 8, 12 hrs concrete specimen were crushed

It is observed from Table No.5, that, Percentage weight loss of High Strength Self Compacting Concrete Cube Specimens at 28 days with respect to Room Temperature for 2000 C varied from 0.79 to 1.60 at 4 hrs, 1.96 to 2.43 at 8 hrs, 3.07 to 3.57 at 12 hrs, for

4000C varied from 3.92 to 5.05 at 4 hrs, 5.51 to 5.81 at 8 hrs, 6.98

to 7.96 at 12 hrs, for 6000C at 4, 8, 12 hrs concrete specimen were crushed

It is observed from Table No.6, that, Pulse Velocity (m/sec) of High Strength Self Compacting Concrete Cube Specimens at 28 days for Room Temperature varied from 4370 to 4430, for 2000 C

varied from 4270 to 4390 at 4 hrs, 4200 to 4230 at 8 hrs, 4120 to

It is observed from Table No.8, that, Percentage decrease in Split Tensile Strength of High Strength Self Compacting Concrete Specimens at 28 days with respect to Room Temperature for 2000 C varied from 2.96 to 4.01 at 4 hrs, 4.51 to 6.08 at 8 hrs, 6.15 to 8.66

at 12 hrs, for 4000C varied from 9.10 to 10.61 at 4 hrs, 11.61 to

13.89 at 8 hrs, 14.75 to 18.15 at 12 hrs, for 6000C at 4, 8, 12 hrs concrete specimen were crushed

It is observed from Table No.9, that, Percentage weight loss of High Strength Self Compacting Concrete Cylinder Specimens at 28 days with respect to Room Temperature for 2000 C varied from 0.65 to 1.27 at 4 hrs, 1.53 to 1.97 at 8 hrs, 2.43 to 3.04 at 12 hrs, for

4000C varied from 3.37 to 4.02 at 4 hrs, 4.37 to 5.31 at 8 hrs, 6.07

to 6.81 at 12 hrs, for 6000C at 4, 8, 12 hrs concrete specimen were crushed

It is observed from Table No.10, that, Pulse Velocity (m/sec) of High Strength Self Compacting Concrete Cylinder specimens at 28 days at Room Temperature varied from 4730 to 4600, for 2000 C varied from 4650 to 4550 at 4 hrs, 4530 to 4500 at 8 hrs, 4450 to

4350 at 12 hrs, for 4000C varied from 4300 to 4200 at 4 hrs,4030 to

3850 at 8 hrs, 3280 to 3060 at 12 hrs, for 6000C at 4, 8, 12 hrs concrete specimen were crushed

Table 3.0.Compressive Strength of HSSCC Specimen with (w/b= 0.215) at 28 days at Room Temperature, 2000 C, 4000C and 6000C at 4, 8, 12 hours duration

Table 4.0 Percentage Decrease of Compressive Strength of HSCCC Specimen with (w/b=0.215) at 2000 C, 4000C and 6000C at 4, 8, 12 hours duration with respect to 28 days strength

Table 5.0 Percentage Weight Loss of HSSCC Cube Specimen with (w/b=0.215) at 2000 C, 4000C and 6000C at 4, 8, 12 hours duration

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Table 8.0 Percentage decrease of Split Tensile Strength of HSSCC Specimen with (w/b=0.215) at 2000 C, 4000C and 6000C at 4, 8, 12 hours duration with respect to 28 days strength

with respect to 28 days

Table 6.0 Pulse Velocity (m/sec) of HSSCC Cube Specimen with (w/b=0.215) at 28 days at Room Temperature, 2000 C, 4000C and 6000C at 4, 8, 12 hours duration

Table 7.0 Split Tensile Strength of HSSCC Specimen with (w/b=0.215) at 28 days at Room Temperature, 2000 C, 4000C and 6000C at 4, 8, 12 hours duration

Table 9.0 Percentage Weight Loss of HSSCC Cylinder Specimen with (w/b=0.215) at 2000 C, 4000C and 6000C at 4, 8, 12 hours duration with respect to 28 days

Table 10.0 Pulse Velocity (m/sec) of HSSCC Cylinder Specimen with (w/b=0.215) at Room Temperature ,2000 C, 4000C and 6000C at 4, 8, 12 hours duration at 28 days strength

Conclusions

1. The loss of Compressive Strength and Split Tensile strength were nearly 14 % and 9 % at 200 oC and 400 oC for 12 hrs and 24 % and 18 % at 200 oC and 400 oC for 12 hrs.

2. The percentage weight loss of Cube Specimens and Cylinder Specimens were nearly 4 % and 8 % at 200 oC and 400 oC for 12 hrs and 3 % and 7 % at 200 oC and 400 oC for 12 hrs.

3. The Pulse Velocity of Cube Specimens and Cylinder Specimens were nearly 4200 m/sec and 3470 m/sec at 200 oC and 400 oC for 12 hrs and 4350 m/sec and 3060 m/sec at 200 oC and 400 oC for 12 hrs.

4. The specimens when exposed to 600o C for 4, 8, 12 hours duration, all the specimens got totally powdered at this temperature.

5. Ultrasonic pulse velocity measurement can be used to estimate the temperature-related damage in concrete.

References

1. Castilo, C and Durrani A J (1990) Effect of transient high temperature on High strength Concrete,ACI Materials Journal, Jan- February1990, pp 47-53

2. George C. Hoff et.al (2000) elevated temperature effects HSC residual strength, Concrete International,

   April 2000, pp 41-47

3. Janotka, Nurnbergurora T (1990), Thermo- Mechanical properties of PENLY reactor envelop at temperatures up to 200oC, Materials and structures Vol.32, December 1999, pp 719-726

4. Long T. Phan and Nicholas J.Carino Effects of test Conditions and Mixture proportions on Behavior of High Strength concrete Exposed to High Temperatures, ACI Materials Journal, January- February 2002 PP 54-62

5. Srinivasa Rao K, Potha Raju M. & Raju P.S.N Effect of Elevated temperature on compressive strength on HSC made with OPC & PPC, The Indian Concrete Journal, August 2006, PP 43-48

6. Abrams, M.S. 1971, Compressive strength of concrete at temperatures to 166oF, ACI Special Publication SP25, USA, pp. 33-58.

   Davis, H.S.1967,Effects if high-temperature exposure on concrete, Materials Research & Standards, pp.452-459.

   Faiyadh, F.I. & Al-Alusi, M.A. 1989,

   Effect of elevated temperature on splitting tensile strength of fibre concrete, The International Journal of Cement Composites and Lightweight Concrete, 11(3), pp. 175-178.

   Khoury, G.A. 1992, Compressive strength of concrete at high temperatures: a reassessment, Magazine of Concrete Research, 44(161), pp. 291- 309.

   Malhotra, H.L. 1956, The effect of high- temperature on compressive strength, Magazine of Concrete Research, 8(3), pp. 85-94.

   Marshall, A.L. 1972, The thermal properties of concrete, Building Science, 7, pp.167-174. Noumowe, A.N., Clastres, P., Debicki, G. & Bolvin, M. 1994, High temperature effect on high performance concrete (70-600oC) strength and porosity, ACI Special Publication SP145, pp.154-172.

7. Sri Ravindrarajah, R., Residual Compressive and Tensile strengths for High strength Concrete Exposed to High-Temperature up to 800°C, Proceedings nternational Conference on HPHSC, Perth, Australia, August 1998, 633- 645

8. EFNARC, Specifications and guidelines for self compacting concrete, www.efnarc.org

9. Saad M, Abo-EI-Enein S.A, Hanna G.B and Kolkata

   M.F Effect of Temperature on Physical and Mechanical Properties of Concrete Containing Silica Fume, Cement and Concrete Research, VoI.26,No.5, 669-675.

10. Shirley T Scott, Ronald G.Burg and Anthony E. Fiorato, Fire Endurance of High-Strength Concrete Slabs,

    ACI Materials Journal, March-April 1988, 102-108

11. Shirley T Scott, Ronald G.Burg and Anthony E. Fiorato, Fire Endurance of High-Strength Concrete Slabs,

    ACI Materials Journal, March-April 1988, 102-108

12. Bai, Sharada Bai, Swamy, Jagadish (1998) Effect of elevated temperature on high strength concrete, National seminar on advances in special concretes, 1998. pp 294-304

13. NAN S., KUNG C., and CHAI H., A simple mix design method for self-compacting concrete Cement and Concrete Research Vol. 31, PP. 1799-1807, 2001.

14. J. R. Lawson, L.T. Phan, and F. Davis, "Mechanical Properties of High Performance Concrete after Exposure to Elevated Temperatures", March 2000.

15. J. R. Lawson, L.T. Phan, and F. Davis, "MechanicalISSN: 2278-0181 Properties of High Performance Concrete afterVEolx. 1poIsssuuere8, October – 2012 to Elevated Temperatures", March 2000.

16. M. A. Helal and Kh. M. Heiza "Effect of aggregate type on the behavior of thermally treated SCC", Egyptian Journal of Applied Science, Vol. 21, pp .68-82, 2006

17. NASSIF A. Y., BURLEY E. and RIGDEN S., A new quantitative method of assessing fire damage to concrete structures Magazine of Concrete Research,

    Vol.47, No. 172, PP. 271-278 Sept.1995

18. H. Yang, Y. Lin, C. Hsiao, J. Liu, Evaluating residual compressive strength of concrete at elevated temperatures using ultrasonic pulse velocity, Fire Safety J.

    44 (2009) 121130

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20. Valiasis, P.T., Residual mechanical properties of concrete incorporating different pozzolanic materials , Materials and Structures,

    Vol. 24, 1991, pp. 115-121

21. Al-Owaisy, S.R., and Al-Chalabi, N.N., Non destructive tests on concrete exposed to temperatures up to 700o C, Journal of Engineering and Development , Vol. 8 , No. 1 , 2004 , pp. 29-37

22. M. Mazloom, A.A. Ramezanianpour, J.J. Brooks, Effect of silica fume on mechanical properties of high-strength concrete, Cem. Concr. Comp. 26 (2004) 347357.

23. C. Poon, S. Azhal, M. Anson, Y. Wong, Comparison of the strength and durability performance of normal-and high-strength pozzolanic concretes at elevated temperatures, Cem. Concrete. Res. 31 (2001) 12911300.

24. Felicetti, R.; Gambarova, P.G.; Rosati, G.P.; Corsi, F.; Giannuzzi, G.; Residual Mechanical Properties of HSC Subjected to High-Temperature Cycles, Proceedings, 4th International Symposium on Utilization of High-Strength/High- Performance Concrete, Paris, France, 1996, pp. 579-588

25. Furumura, F.; Abe, T.; Shinohara, Y.; Mechanical Properties of High Strength Concrete at High Temperatures, Proceedings, Fourth Weimar Workshop on High strength Concrete: Material Properties and Design. Hochschule für Architektur und Bauwesen (HAB), Weimar, Germany, October 4th and 5th, 1995, pp. 237 – 254

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236

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Fig. 3.0.Variation of Compressive Strength at Room Temperature, 200, 400, 6000 C for exposure duration of 4, 8, 12 hrs at 28 days

Fig. 4.0.Percentage decrease in Compressive Strength at 200, 400, 6000 C for exposure duration of 4, 8, 12 hrs with respect to Room Temperature at 28 days

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Fig. 5.0.Percentage weight loss of cube specimens at 200, 400, 6000 C for exposure duration of 4, 8, 12 hrs with respect to Room

Temperature at 28 days

Fig. 6.0. Variation of Pulse Velocity (m/sec) of Cube Specimens at Room Temperature, 200, 400, 6000 C for exposure duration of

4, 8, 12 hrs at 28 days

Fig. 7.0. Variation of Split Tensile Strength at Room Temperature, 200, 400, 6000 C for exposure duration of 4, 8, 12 hrs at 28 days

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Fig. 8.0.Percentage decrease in Split Tensile Strength at 200, 400, 6000 C for exposure duration of 4, 8, 12 hrs with respect to Room Temperature at 28 days

Fig. 9.0.Percentage weight loss of cylinder specimens at 200, 400, 6000 C for exposure duration of 4, 8, 12 hrs with respect to Room Temperature at 28 days

Fig. 10.0. Variation of Pulse Velocity (m/sec) of Cylinder Specimens at Room Temperature, 200, 400, 6000 C for exposure duration of 4, 8, 12 hrs at 28 days

ABOUT THE AUTOHRS

R. Vasusmitha is currently working as Senior Manager (Designs) in M/s Afcons Infrastructure limited, Mumbai. She has about 15 years of Industrial experience in various fields of Marine structures, Bridges, Industrial Buildings etc., Graduated and Post Graduated from J.N.T.U College of Engineering, Hyderabad in Civil Engineering. Research Scholar under esteemed guidance of Dr.P.Srinivasa Rao, Head of Department, Civil Engineering J.N.T.U Hyderabad.

Vol. 1 Issue 8, October – 2012

Dr P. Srinivasa Rao is currently working as Professor in the Department of Civil Engineering, J.N.T University College of Engineering, Kukatpally, Hyderabad. He has about 25 years of experience in Teaching and Research. He is presently Head of Department, Civil Engineering J.N.T.U Hyderabad. He has guided many PhDs and involved in R& D activities. Apart from general Structural Engineering, the Special Concretes like Self Compacting Concrete, SFR- SCC, and HPC are the fields of his special interest.