YÜK UYGULANMAMIŞ VE PLASTİK DEFORMASYONA UĞRATILMIŞ HTPP-ECC’LERİN TERMAL YALITIM PERFORMANSI ÜZERİNE KARŞILAŞTIRMALI BİR İNCELEME

Öz

Mühendislikçe geliştirilmiş çimentolu kompozitler (ECC) mikro-mekanik olarak tasarlanan geleneksel betona kıyasla yüksek performanslı kompozitlerdir. Mevcut literatürdeki önemli sayıda araştırma, ECC'lerin mekanik performansının ve sünekliğinin geliştirmesine odaklanmaktadır. Bu çalışmada, ECC'nin HTPP-ECC isimli özel bir türünün termal özellikleri araştırılmıştır. Bu amaç doğrultusunda, prizmatik kompozitler hazırlanmış ve termal iletkenlik deneyleri gerçekleştirilmiştir. Deney sonuçları mevcut literatürden elde edilen verilerle kıyaslanmıştır. Ayrıca, HTPP-ECC'lerin mekanik performansı ve çoklu çatlama yeteneği eğilme yükü altında test edilmiştir. Mevcut literatüre ek olarak, HTPP-ECC'lerin termal ısı yalıtım performansı, çatlamamış (eğilme testinden önce), çatlatılmış (tepe yüklemesinden sonra yük düşüşü % 10'a kadar) ve göçmüş (numunenin altında 5 mm genişliğinde büyük çatlak oluşana kadar) durumlarda gerçek saha koşullarını taklit eden bir yalıtım testi kurulumu kullanılarak test edilmiştir. Kararlı haldeki mikro-çatlakların HTPP-ECC'nin ısı yalıtım performansı üzerindeki etkisi değerlendirilmiştir. Sonuç olarak, bu çalışmada üretilen HTPP-ECC'lerin plastik olarak deforme olmuş halde bile çimento esaslı diğer materyallere kıyasla daha iyi bir termal iletkenlik performansı sergilediğini göstermiştir. Ayrıca, HTPP-ECC'ler mikro-çatlaklı halde bile gelişmiş mekanik özelliklere ve çoklu kırma yeteneğine sahip umut verici alternatif bir ısı yalıtım malzemesi olarak etkili bir ısı yalıtımı performansı sergilemiştir.

Anahtar Kelimeler

• Termal özellikler
• Mühendislikçe geliştirilmiş çimentolu kompozitler
• HTPP
• lif
• uzun dönem

A COMPARATIVE STUDY ON THE THERMAL INSULATION PERFORMANCE OF UNLOADED AND PLASTICALLY DEFORMED HTPP-ECC

Öz

Engineered Cementitious Composite (ECC) is a type of micro-mechanically designed, high performance composite compared to conventional concrete. A considerable number of research in the existing literature concentrate on mechanical performance and ductility improvement of ECCs. In this paper, thermal properties of special type of ECC incorporating high tenacity polypropylene fiber by 2% of total matrix volume (HTPP-ECC) have been investigated. For this purpose, prismatic composites were prepared and thermal conductivity tests were performed. Tests results were compared with the data obtained from existing literature. The mechanical performance and multiple cracking ability of HTPP-ECCs were also tested under bending load. In addition to the existing literature, thermal heat insulation performance of HTPP-ECCs have been tested at virgin (before bending test), cracked (up to 10% of load drop after peak load) and failed (up to 5 mm major crack width at the bottom of the specimen) state by using an insulation test setup which simulates actual site conditions. The effect of steady state micro-cracking on the thermal insulation performance of HTPP-ECC was evaluated. Results showed that, HTPP-ECCs produced in this study has better performance in terms of thermal conductivity when compared to other types of cement-based materials even at the plastically deformed state. Also, HTPP-ECCs exhibited an effective thermal insulation performance even in micro-cracked state as a promising alternative thermal insulation material with improved mechanical properties and multiple cracking ability.

Anahtar Kelimeler

• Thermal properties
• Engineered Cementitious Composites
• HTPP
• fiber
• long term

Kaynakça

1. ASTM C1113/C1113M-09, 2009, Standard Test Method for Thermal Conductivity of Refractories by Hot Wire (Platinum Resistance Thermometer Technique), ASTM International, West Conshohocken, PA, www.astm.org. doi: 10.1520/C1113_C1113M-09
2. ASTM C150/C150M-17, 2017, Standard Specification for Portland Cement, ASTM International, West Conshohocken, PA, www.astm.org. doi: 10.1520/C0150_C0150M-17
3. ASTM C323-56, 2016, Standard Test Methods for Chemical Analysis of Ceramic Whiteware Clays, ASTM International, West Conshohocken, PA, www.astm.org. doi: 10.1520/C0323-56R16
4. ASTM C325-81, 2007, Standard Test Method for Wet Sieve Analysis of Ceramic Whiteware Clays, ASTM International, West Conshohocken, PA, www.astm.org. doi: 10.1520/C0325-81R07
5. ASTM C371-09, 2014, Standard Test Method for Wire-Cloth Sieve Analysis of Nonplastic Ceramic Powders, ASTM International, West Conshohocken, PA, www.astm.org. doi: 10.1520/C0371-09R14
6. ASTM D854-14, 2014, Standard Test Methods for Specific Gravity of Soil Solids by Water Pycnometer, ASTM International, West Conshohocken, PA, www.astm.org. doi: 10.1520/D0854-14
7. ASTM E313-15e1, 2015, Standard Practice for Calculating Yellowness and Whiteness Indices from Instrumentally Measured Color Coordinates, ASTM International, West Conshohocken, PA, www.astm.org. doi: 10.1520/E0313-15E01
8. Chen, Z., Li, J. and Yang, E., 2016, High strength lightweight strain-hardening cementitious composite incorporating cenosphere. 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures (FraMCoS 9), V. Saouma, J. Bolander and E. Landis(Eds). doi:10.21012/FC9.130

9. Chwieduk, D.A., 2017, Towards modern options of energy conservation in buildings. Renew. Energy, 101, 1194–1202. doi:10.1016/j.renene.2016.09.061
10. Desai, D., Miller, M., Lynch, J.P. and Li, V.C., 2014, Development of thermally adaptive Engineered Cementitious Composite for passive heat storage. Construction and Building Materials, 67, 366–372. doi:10.1016/j.conbuildmat.2013.12.104
11. EN 196-1, 2005, Methods of testing cement–Part 1: Determination of strength. European Committee for standardization, 26. Felekoglu, B. and Keskinates, M., 2016 Multiple cracking analysis of HTPP-ECC by digital image correlation method, Computers and Concrete, 17(6), 831-848. doi:10.12989/cac.2016.17.6.831
12. Hanif, A., Diao, S., Lu, Z., Fan, T. and Li, Z., 2016, Green lightweight cementitious composite incorporating aerogels and fly ash cenospheres - Mechanical and thermal insulating properties. Construction and Building Materials, 116, 422–430. doi:10.1016/j.conbuildmat.2016.04.134
13. Huang, X., Ranade, R., Zhang, Q., Ni, W. and Li, V.C., 2013, Mechanical and thermal properties of green lightweight engineered cementitious composites. Construction and Building Materials, 48, 954–960. doi:10.1016/j.conbuildmat.2013.07.104
14. Iffat, S., 2015, Relation between density and compressive strength of hardened concrete. Concrete Research Letters, 6(4), 182-189.
15. Ikai, S., Reichert, J.R., Vasconcellos, A.R. and Zampieri, V.A., 2006, Asbestos-free technology with new high tenacity PP–polypropylene fibers in air-cured Hatschek process. In 10th Int. Inorganic-bonded Fiber Composites Conference (IIBCC 2006), Brazil. October 15 - 18, 2006. Universidade de Sao Paulo & University of Idaho: Sao Paulo, pp. 33-48.
16. Li, V.C. and Kanda, T., 1998 Innovations forum: engineered cementitious composites for structural applications, Journal of Materials in Civil Engineering, 10(2), 66-69.
17. Li, V.C., 1997, Engineered cementitious composites-tailored composites through micromechanical modeling., Proceedings of Fiber Reinforced Concrete: Present and the Future, N. Banthia, A. Bentur, A. Mufti (Eds.), Canadian Society of Civil Engineers (CSCE), Montreal, Canada, p. 38.
18. Li, V.C., Wang, S. and Wu, C., 2001, Tensile strain-hardening behavior of polyvinyl alcohol engineered cementitious composite (PVA-ECC), ACI Materials Journal-American Concrete Institute, 98(6), 483-492.
19. Li, V.C., Wu, H.C. and Chan, Y.W., 1996, Effect of plasma treatment of polyethylene fibers on interface and cementitious composite properties. Journal of the American Ceramic Society, 79(3), 700–704.
20. Mackinnon, I.D.R., Uwins, P.J.R., Yago, A. and Page, D., 1993, Kaolinite particle sizes in the <2 μm range using laser scattering. Clays & Clay Minerals, 41, 613–623. doi:10.1346/CCMN.1993.0410512
21. Muzenski, S., Flores-Vivian, I. and Sobolev, K., 2015, Hydrophobic engineered cementitious composites for highway applications, Cement and Concrete Composites, 57, 68-74. doi: 10.1016/j.cemconcomp.2014.12.009
22. Neville, A.M., 1995, Properties of Concrete, Longman Scientific and Technical, 844p.
23. Rokugo, K., Kanda, T., Yokota, H. and Sakata, N., 2009, Applications and recommendations of high performance fiber reinforced cement composites with multiple fine cracking (HPFRCC) in Japan. Materials and Structures, 42, 1197–1208. doi:10.1617/s11527-009-9541-8.
24. Xu, B. and Li, Z., 2014, Performance of novel thermal energy storage engineered cementitious composites incorporating a paraffin/diatomite composite phase change material. Applied Energy, 121, 114–122. doi:10.1016/j.apenergy.2014.02.007
25. Yang, E.H., 2006, Designing added functions in engineered cementitious composites, Ph.D. thesis (Civil Engineering), The University of Michigan, 276p.
26. Zhang, Q. and Li, V.C., 2015, Development of durable spray-applied fire-resistive Engineered Cementitious Composites (SFR-ECC). Cement and Concrete Composites, 60, 10–16. doi:10.1016/j.cemconcomp.2015.03.012