İsmail Ağa GÖNÜL, Hatice ÇİÇEK

The size of portlandite crystals in ITZ and its relation with ratios of ingredients and properties of LWAC

In this experimental study, nine different lightweight aggregate concrete (LWAC) specimens - in which natural lightweight scoria aggregate was used as coarse aggregate - were prepared for investigating the size of portlandite crystals in their interfacial transition zone (ITZ). Scanning Electron Microscope (SEM) was used to determine the size of portlandite crystals in ITZ of LWAC specimens. The size of portlandite crystals in ITZ of these LWAC specimens was determined quantitatively in order to identify its relation with ratios of ingredients and properties of LWAC that were investigated. It was determined that the size of portlandite crystals in ITZ of nine LWAC specimens is in the range of (0.91-2.047) µm. The size of portlandite crystals in ITZ is found to be increased when the water/cement (W/C) and coarse aggregate/total aggregate (Ac/A) ratios of LWAC get increased. On the other hand, the compressive strength and the oven-dry density of LWAC are found to be decreased when the size of portlandite crystals in ITZ gets increased. The best way to make portlandite beneficial from mechanical, physical and durability points of view is to transform it into so-called secondary hydration products by making it react with materials that have proper chemical properties for this transformation. In this case, the small portlandite crystals dissolve entirely, and the large portlandite crystals become smaller. Lightweight scoria aggregate used in this study is thought to have chemical properties to assist such a transformation in ITZ.

Anahtar Kelimeler:

Lightweight aggregate concrete, scoria, interfacial transition zone, portlandite, compressive strength, oven-dry density

The size of portlandite crystals in ITZ and its relation with ratios of ingredients and properties of LWAC

Keywords:

Lightweight aggregate concrete, scoria, interfacial transition zone, portlandite, compressive strength, ven-dry density,

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J. J. Thomas and H. Jennings, “Materials of cement science primer: The science of concrete,” Northwestern University Infrastructure Technology Institute, USA, Rep. Project A474, 2009.
P. K. Mehta and P. J. M. Monteiro, Concrete - Microstructure, Properties, and Materials. Third ed., New York, NY, USA: McGraw-Hill, 2006.
K. M. Nemati, P. J. M. Monteiro, and K. L. Scrivener, “Analysis of compressive stress-induced cracks in concrete,” ACI Mater. J., vol. 95, no. 5, pp. 617-631, 1998.
L. Basheer, P. A. M. Basheer, and A. E. Long, “Influence of coarse aggregate on the permeation, durability and the microstructure characteristics of ordinary Portland cement concrete,” Constr. Build. Mater., vol. 19, pp. 682-690, 2005.
V. W. Y. Tam, X. F. Gao, and C. M. Tam, “Microstructural analysis of recycled aggregate concrete produced from two-stage mixing approach,” Cem. Concr. Res., vol. 35, pp. 1195-1203, 2005.
A. Cwirzen and V. Penttala, “Aggregate–cement paste transition zone properties affecting the salt–frost damage of high-performance concretes,” Cem. Concr. Res., vol. 35, pp. 671-679, 2005.
H. Gönül, “Bazalt skoriasının taşıyıcı yarı hafif beton üretiminde kullanımı / Use of basaltic scoria for produce of semi lightweight concrete,” Ph.D. dissertation, Dept. of Architecture, Gazi Univ., Ankara, 2008.
M. Ayhan, H. Gönül, İ. A. Gönül, and A. Karakuş, “Effect of basic pumice on morphologic properties of interfacial transition zone in load-bearing lightweight / semi-lightweight concretes,” Constr. Build. Mater., vol. 25, pp. 2507-2518, 2011.
E. Gallucci and K. Scrivener, “Crystallisation of calcium hydroxide in early age model and ordinary cementitious systems,” Cem. Concr. Res., vol. 37, pp. 492-501, 2007.
J. Skalny, J. Gebauer, and I. Odler, eds., Materials Science of Concrete: Calcium Hydroxide in Concrete. Westerville, USA: The American Ceramic Society, 2001.
C. Carde and R. François, “Effect of the leaching of calcium hydroxide from cement paste on the mechanical and physical properties,” Cem. Concr. Res., vol. 27, pp. 539-550, 1997.
N. Hernandez, J. Lizarazo-Marriaga, and M. A. Rivas, “Petrographic characterization of Portlandite crystal sizes in cement pastes affected by different hydration environments,” Constr. Build. Mater., vol. 182, pp. 541-549, 2018.
T. Sacki and P. J. M. Monteiro, “A model to predict the amount of calcium hydroxide in concrete containing mineral admixtures,” Cem. Concr. Res., vol. 35, pp. 1914-1921, 2005.
J. Marchand, D. P. Bentz, E. Samson, and Y. Maltais, “Influence of calcium hydroxide dissolution on the transport properties of hydrated cement systems,” in Materials Science of Concrete: Calcium Hydroxide in Concrete, J. Skalny, J. Gebauer, and I. Odler, eds., Westerville, USA: The American Ceramic Society, 2001, pp. 113-129.
Z. Yan-Rong, K. Xiang-Ming, L. Zi-Chen, L. Zhen-Bao, Z. Qing, D. Bi-Qin, and X. Feng, “Influence of triethanolamine on the hydration product of portlandite in cement paste and the mechanism,” Cem. Concr. Res., vol. 87, pp. 64-76, 2016.
T. Müller, C. Krämer, C. Pritzel, R. Bornemann, T. L. Kowald, R. H. F. Trettin, and P. H. Bolívar, “Influence of cocamidopropyl betaine on the formation and carbonation of portlandite – A microscopy study,” Constr. Build. Mater., vol. 163, pp. 793-797, 2018.
W. Kunther, S. Ferreiro, and J. Skibsted, “Influence of the Ca/Si ratio on the compressive strength of cementitious calcium–silicate–hydrate binders,” J. Mater. Chem. A, vol. 5, pp. 17401-17412, 2017.
S. Diamond, “The microstructure of cement paste and concrete––a visual primer,” Cem. Concr. Compos., vol. 26, pp. 919-933, 2004.
K. Wu, H. Shi, L. Xu, G. Ye, and D. G. Schutter, “Microstructural characterization of ITZ in blended cement concretes and its relation to transport properties,” Cem. Concr. Res., vol. 79, pp. 243-256, 2016.
J. S. Belkowitz and D. Armentrout, “An investigation of nano silica in the cement hydration process,” presented at the Concrete Sustainability Conference, USA, 2010.
Q. Ye, Z. Zhang, D. Kong, and R. Chen, “Influence of nano-SiO2 addition on properties of hardened cement paste as compared with silica fume,” Constr. Build. Mater., vol. 21, pp. 539-545, 2007.
P. C. Aitcin, “Portland cement,” in Science and Technology of Concrete Admixtures, P. C. Aitcin and R. J. Flatt, eds., UK: Woodhead Publishing, 2016, pp. 27-53.
T. Slamečka and F. Škvára, “The effect of water ratio on microstructure and composition of the hydration products of Portland cement pastes,” Ceram. Silik., vol. 46, no. 4, pp. 152-158, 2002.
Testing hardened concrete - Part 1: Shape, dimensions and other requirements for specimens and moulds, TS EN 12390-1, 2002.
Testing hardened concrete - Part 2: Making and curing specimens for strength tests, TS EN 12390-2, 2002.
Testing hardened concrete - Part 3: Compressive strength of test specimens, TS EN 12390-3, 2003.
Testing hardened concrete - Part 4: Compressive strength - Specification for testing machines, TS EN 12390-4, 2002.
Testing hardened concrete - Part 7: Density of hardened concrete, TS EN 12390-7, 2002.
L. Jiang, “The interfacial zone and bond strength between aggregates and cement pastes incorporating high volumes of fly ash,” Cem. Concr. Compos., vol. 21, pp. 313-316, 1999.
J. M. Gao, C. X. Qian, H. F. Liu, B. Wang, and L. Li, “ITZ microstructure of concrete containing GGBS,” Cem. Concr. Res., vol. 35, pp. 1299-1304, 2005.
J. Ren, Y. Lai, and J. Gao, “Exploring the influence of SiO2 and TiO2 nanoparticles on the mechanical properties of concrete,” Constr. Build. Mater., vol. 175, pp. 277-285, 2018.
The Concrete Countertop Institute, “The importance of water/cement ratio in concrete countertop mix design,” 2019. [Online]. Available: https://concretecountertopinstitute.com/free-training/the-importance-of-water-cement-ratio-in-concrete-countertop-mix-design/, Accessed on: 6 October 2019.
M. Ivanov and O. Shenderova, “Nanodiamond-based nanolubricants for motor oils,” Curr. Opin. Solid State Mater. Sci., vol. 21, pp. 17-24, 2017.
V. W. Y. Tam, X. F. Gao, and C. M. Tam, “Carbonation around near aggregate regions of old hardened concrete cement paste,” Cem. Concr. Res., vol. 35, pp. 1180-1186, 2005.
E. Lake, “Van Der Waals Forces & Static Electricity: How They Affect Bacillus Spores,” 2008. [Online]. Available: https://www.anthraxinvestigation.com/SporeInteraction.html, Accessed on: 6 October 2019.