Evaluación ocupacional

An experimental program was conducted to investigate the influence of steel, glass and steel-glass hybrid fibres on the compressive strength, modulus of elasticity, indirect tensile strength and shear strength of RPC. Based on the experimental results of this study, the following main conclusions can be drawn.

33

1. The ratio of the compressive strength at 7 days to the compressive strength at 28 days for NF-RPC was 88%. The ratio of compressive strength at 56 days to the compressive strength at 28 days for NF-RPC was 113%. The ratio of compressive strength at 7 days to the compressive strength at 28 days for NF-RPC was found to be about 33% higher than that of normal strength concrete. The ratio of compressive strength at 56 days to the compressive strength at 28 days for NF- RPC was found to be similar to that of normal strength concrete. The addition of steel fibres in the RPC increased the average compressive strength by 6.6%, while the addition of the glass and the hybrid (steel plus glass) fibres in the RPC decreased the average compressive strength by 10% and 5.5%, respectively, compared to the average compressive strength of NF-RPC.

2. The average modulus of elasticity of NF-RPC was 39 GPa. The SFR-RPC achieved modulus of elasticity marginally higher than that of NF-RPC, and HFR-RPC achieved modulus of elasticity equals to that of NF-RPC. In contrast, the average modulus of elasticity for GFR-RPC was 5% lower than the modulus of elasticity for NF-RPC.

3. Average splitting tensile strength of NF-RPC increased by about 30% and 20% with the addition of the steel and hybrid steel-glass fibres, respectively. However, the average splitting tensile strength of NF-RPC decreased by 25% after the addition of the glass fibres.

4. The average shear strength of RPC under direct shear demonstrated a significant improvement with the addition of the fibres (steel, glass and steel-glass fibres). The SFR-RPC achieved average shear strength about 150% higher than that of NF-RPC. Also, the average shear strengths of GFR-RPC and HFR-RPC were about 60% and 120%, respectively, higher than that of NF-RPC.

34

Acknowledgements

The authors acknowledge the University of Wollongong, Australia, for the financial support to this experimental study. The authors acknowledge, Australasian (iron & steel) Slag Association for the free supply of the silica fume. The first author would like to acknowledge the Iraqi government for the full financial support to his PhD study. Special thanks to all technical staff in the Structural Engineering laboratories at the University of Wollongong, Australia.

References

[1] P. Richard, M. Cheyrezy, Composition of reactive powder concretes, Cement and concrete research 25(7) (1995) 1501-1511.

[2] M.-G. Lee, Y.-C. Wang, C.-T. Chiu, A preliminary study of reactive powder concrete as a new repair material, Construction and Building Materials 21(1) (2007) 182-189.

[3] Z. Yunsheng, S. Wei, L. Sifeng, J. Chujie, L. Jianzhong, Preparation of C200 green reactive powder concrete and its static–dynamic behaviors, Cement and Concrete Composites 30(9) (2008) 831-838.

[4] T. Chang, B. Chen, J. Wang, C. Wu, Performance of Reactive Powder Concrete (RPC) with different curing conditions and its retrofitting effects on concrete member, In: Alexander et al (Eds.), Concrete Repair, Rehabilitation and Retrofitting II, Taylor & Francis Group, London, UK, 2009, pp. 1203-1208.

[5] A.R. Malik, S.J. Foster, Carbon fibre-reinforced polymer confined reactive powder concrete columns-experimental investigation, ACI Structural Journal 107(03) (2010) 263-271.

35

[6] Lee N P, Chisholm D H, Reactive Powder Concrete, New Zealand, Study Report no. SR146 (2005), 1-29.

[7] C.M. Tam, K.M. Ng, V.W.Y. Tam, Optimal conditions for producing reactive powder concrete, Magazine of Concrete Research 62(10) (2010) 701-716.

[8] P.N. Hiremath, S.C. Yaragal, Effect of different curing regimes and durations on early strength development of reactive powder concrete, Construction and Building Materials 154 (2017) 72-87.

[9] A. Al-Tikrite, M.N. Hadi, Mechanical properties of reactive powder concrete containing industrial and waste steel fibres at different ratios under compression, Construction and Building Materials 154 (2017) 1024-1034.

[10] C.-T. Liu, J.-S. Huang, Fire performance of highly flowable reactive powder concrete, Construction and Building Materials 23(5) (2009) 2072-2079.

[11] S. Ahmad, A. Zubair, M. Maslehuddin, Effect of key mixture parameters on flow and mechanical properties of reactive powder concrete, Construction and Building Materials 99 (2015) 73-81.

[12] Y. Ju, Y. Jia, H. Liu, J. Chen, Mesomechanism of steel fibre reinforcement and toughening of reactive powder concrete, Science in China Series E: Technological Sciences 50(6) (2007) 815-832.

[13] E. Shaheen, N. Shrive, Optimization of mechanical properties and durability of reactive powder concrete, ACI Materials Journal 103(6) (2006) 444-451.

[14] S. Sanchayan, S.J. Foster, High temperature behaviour of hybrid steel–PVA fibre reinforced reactive powder concrete, Materials and Structures 48(1) (2015) 1-15. [15] M. Canbaz, The effect of high temperature on reactive powder concrete, Construction and Building Materials 70 (2014) 508-513.

36

[16] J.P.J.G. Ferreira, F.A.B. Branco, The Use of Glass Fiber-Reinforced Concrete as a Structural Material, Experimental Techniques 31(3) (2007) 64-73.

[17] G R C A, Specifiers Guide to Glass Reinforced Concrete, Glass Reinforced Concrete Association, UK (2012) 1-4.

[18] AS 3972-2010, General purpose and blended cements, Australian Standards, Sydney, NSW, 2010.

[19] SIMCOA operations pty. ltd., Micro silica material safety data sheet,

http://www.simcoa.com.au/, 2018 (accessed 06.04.18).

[20] Australasian (iron & steel) Slag Association (ASA), Wollongong, NSW, Australia. http://www.asa-inc.org.au/, 2018 (accessed 06.04.18).

[21] BASF-Australia, Master Glenium® SKY 8700-technical data sheet.

http://www.BASF.cam.au/, 2018 (accessed 06.04.18).

[22] Ganzhou Daye Metallic Fibres Co.,Ltd, Micro steel fibre WSF0213 III specifications. http://www.gzdymf.com/, 2018 (accessed 06.04.18).

[23] Nippon Electric Glass Co., Ltd., (NEG), High Integrity chopped strand alkali resistant glass fibre. http://www.neg.co.jp/EN/common/image/header_logo.gif, 2018

(accessed 06.04.18).

[24] ASTM C230/C230M-14, Standard Specification for Flow Table for use in Tests of Hydraulic Cement, American Society for Testing and Materials, West Conshohocken, PA, United States, 2014.

[25] A.R. Malik, S.J. Foster, Behaviour of reactive powder concrete columns without steel ties, Journal of advanced concrete technology 6(2) (2008) 377-386.

[26] AS 1012.9, Compressive strength tests – concrete, mortar and grout specimen, Australian Standards, Sydney, NSW, 2014.

37

[27] AS 1012.17, Methods of testing concrete: Determination of the static chord modulus of elasticity and Poisson's ratio of concrete specimens, Australian Standards, Sydney, NSW, 2014.

[28] AS 1012.10, Determination of indirect tensile strength of concrete cylinders, Australian Standards, Sydney, NSW, 2014.

[29] JS SF6, Method of test for shear strength of steel fibre reinforced concrete, Japan Society of Civil Engineers (JSCE), Tokyo, Japan, 1999.

[30] R. Anderson, J. Dewar, Manual of ready-mixed concrete, 3thed, London, CRC Press, 2003.

[31] M.N.S. Hadi, Behaviour of eccentric loading of FRP confined fibre steel reinforced concrete columns, Construction and Building Materials 23(2) (2009) 1102- 1108.

[32] Y.-C. Ou, M.-S. Tsai, K.-Y. Liu, K.-C. Chang, Compressive behavior of steel- fiber-reinforced concrete with a high reinforcing index, Journal of Materials in Civil Engineering 24(2) (2011) 207-215.

[33] P. K. Mehta, P. J. M. Monteiro, Concrete: Microstructure, Properties, and Materials, 4th_{edn, New York, McGraw-Hill Education, 2014.}

[34] M. Maroliya, Behaviour of reactive powder concrete in direct shear, IOSR Journal of Engineering (IOSRJEN) 2(9) (2012) 76-79.

[35] B. Boulekbache, M. Hamrat, M. Chemrouk, S. Amziane, Influence of yield stress and compressive strength on direct shear behaviour of steel fibre-reinforced concrete, Construction and Building Materials 27(1) (2012) 6-14.

38

Summary

The purpose of the pilot study presented in this chapter was to examine the mechanical properties of NF-RPC and FR-RPC. This was done to determine the most suitable RPC mix to be used as an efficient jacketing material for RC columns. Based on the experimental results of this pilot study, the SFR-RPC mix was found to be the most efficient mix to be used as a jacketing material for RC columns from a structural perspective. However, GFR-RPC and HFR-RPC were proposed to be used as jacketing materials in further studies. The GFR-RPC and HFR-RPC can be considered as alternatives for the SFR-RPC in the corrosive environments. The next chapter presents an experimental preliminary study to investigate the axial and flexural behaviour of circular RC columns strengthened with SFR-RPC jacket and FRP wrapping.

39

3. Axial and Flexural Behaviour of Circular Reinforced