Investigation of Alkaline Activator ratio on Geopolymer Concrete under Ambient Curing Regime

Yıl 2019, Cilt: 4 Sayı: 2, 89 - 100, 05.08.2019

Hayder Alı , Nildem Tayşi

Öz

Geopolymerisation
allows the reuse and refurbishment of an extensive range of waste materials
into building elements with excellent mechanical and durability properties,
giving it potential as an environmentally friendly alternative to conventional
concrete. In this paper, ground granulated blast furnace slag (GGBFS) was
blended with fly ash (FA) to form binder content (B) and combined at different
ratios with a solution of various alkaline activators (ALA) to make Geopolymer concrete
(GPC). The ALA solution consisted of a mixture of sodium silicate (Na₂SiO₃)
and sodium hydroxide (NaOH), with a stable NaOH concentration of 12 M (Molar) and
a Na₂SiO₃/NaOH mass ratio of 2.5. The GPC mixes were
prepared with different ALA/B ratios (0.33, 0.375, 0.40 and 0.42), and a
constant partial GGBFS/FA replacement ratio was used. All of the mixes were
cured under ambient conditions. To analyses the impact of the ALA/B ratio on
the GPC, the compressive and splitting tensile strengths of hardened GPC were
investigated and the density was measured at two different ages, 7 and 28 days.
The experimental results showed that varying the ALA/B ratio had an influence
on the compressive strength of GPC. Compressive strength was higher at an ALA/B
ratio of 0.375 than at both higher and lower ratios. At this optimum ALA/B
ratio, compressive strength of up to 57.76 MPa was recorded on the 28th day.
Additionally, the hardened density of GPC ranged between 2203 and 2279 kg/m³.
Finally, a relationship is proposed between compressive strength and tensile
strength.

Anahtar Kelimeler

Geopolymer concrete, Alkali-activate ratio, Compressive strength, Tensile strength, Ambient curing

Doğal Kürleme Şartlarında Alkali Aktivatör Oranının Jeo-Polimer Betona Etkisinin İncelenmesi

Öz

Jeo-polimerizasyon, çeşitli atık malzemeleri sıradan betona kıyasla daha
iyi mekanik ve dayanıklılık özelliklerine sahip yapı malzemelerine
dönüştürebilmektedir. Bu çalışmada, cüruf (GGBFS) Fly-Ash (FA) le
karıştırılarak ve farklı alkalin-aktivatörler (Al) farklı bağlayıcı aktivatör
oranları (AlA/B) ile harmanlanarak, geopolimer beton (GPC) hazırlanmasında
kullanılmıştır. Sodyum silikat (Na₂SiO₃) ve sodyum
hidroksit (NaOH) çözeltisi, 12 M lik sabit NaOH konsantrasyonu ve Na₂SiO₃/NaOH
oranı 2.5 ile alkalin aktivatörü olarak kullanılmıştır. GPC karışımları, farklı
AlA/B oranlarıyla (0.33, 0.37, 0.40 ve 0.42) hazırlanmış ve GPC ye aktivatör
oranının etkisinin incelenmesi açısından, sabit bir GGBFS/FA oranı
kullanılmıştır. Sertleşmiş GPC iki farklı yaşta (7, 28 gün) ve yoğunlukta
basınç ve çekme mukavemeti deneylerine tabi tutulmuştur. Bütün karışımlar doğal
kürleme şartlarında sertleştirilmiştir. Deneysel sonuçlar, çeşitli AlA/B
oranlarının GPC'nin basınç dayanımı üzerinde etkili olduğunu göstermiştir. AlA/B
oranını düşerken basınç dayanımı artmaktadır. 28 günde 57.76 MPa'ya kadar
basınç dayanımı gösteren 0.375 optimum AIA/B oranıdır. Ayrıca, GPC nin
yoğunluğu 2203 kg/m³ ila 2279 kg/m³ arasında
değişmektedir. Sonuç olarak, basınç dayanımı ve çekme dayanımı arasında bir
ilişki önerilmiştir.

Anahtar Kelimeler

Jeo-polimer beton, Alkali-aktivatör oranı, Basınç dayanımı, Cekme dayanımı, Doğal kürleme

Kaynakça

• [1] V. M. Malhotra, “Introduction: sustainable development and concrete technology,” Concrete International, vol. 24, no. 7, 2002.
• [2] K. L. Scrivener and R. J. Kirkpatrick, “Innovation in use and research on cementitious material,” Cement and concrete research, vol. 38, no. 2, pp. 128–136, 2008.
• [3] V. M. Malhotra, “Making concrete‘ greener’ with fly ash,” Concrete international, vol. 21, no. 5, pp. 61–66, 1999.
• [4] ACI Committee 232, “Use of Raw or Processed Natural Pozzolans in Concrete,” American concrete institute, pp. 1–24, 2001.
• [5] ACI Committee 211, “ACI 211.4R-93 Guide for Selecting Proportions for High-Strength Concrete with Portland Cement and Fly Ash,” Manual of Concrete Practice, vol. 93, no. Reapproved, p. 13, 1998.
• [6] ACI Committee 233, “Slag Cement in Concrete and Mortar,” American Concrete Institute, no. ACI 233R-03, pp. 1–19, 2003.
• [7] A. Nazari and J. G. Sanjayan, Handbook of Low Carbon Concrete. 2017.
• [8] J. Davidovits, “The need to create a new technical language for the transfer of basic scientific information,” Transfer and Exploitation of Scientific and Technical Information, EUR, vol. 7716, pp. 316–320, 1982.
• [9] J. Davidovits, “Geopolymers - Inorganic polymeric new materials,” Journal of Thermal Analysis, vol. 37, no. 8, pp. 1633–1656, 1991.
• [10] J. Davidovits, Geopolymer chemistry and applications. Geopolymer Institute, 2008.
• [11] P. Duxson, A. Fernández-Jiménez, J. L. Provis, G. C. Lukey, A. Palomo, and J. S. J. Van Deventer, “Geopolymer technology: The current state of the art,” Journal of Materials Science, vol. 42, no. 9, pp. 2917–2933, 2007.
• [12] A. Fernández-Jiménez and A. Palomo, “Composition and microstructure of alkali activated fly ash binder: Effect of the activator,” Cement and Concrete Research, vol. 35, no. 10, pp. 1984–1992, 2005.
• [13] P. R. Vora and U. V Dave, “Parametric Studies on Compressive Strength of Geopolymer Concrete,” Procedia Engineering, vol. 51, pp. 210–219, 2013.
• [14] R. R. Lloyd, J. L. Provis, and J. S. J. Van Deventer, “Microscopy and microanalysis of inorganic polymer cements. 1: Remnant fly ash particles,” Journal of Materials Science, vol. 44, no. 2, pp. 608–619, 2009.
• [15] M. S. Muñiz-Villarreal et al., “The effect of temperature on the geopolymerization process of a metakaolin-based geopolymer,” Materials Letters, vol. 65, no. 6, pp. 995–998, 2011.
• [16] Al-Rawi Saad and Tayşi Nildem, “Performance of self-compacting geopolymer concrete with and without GGBFS and steel fiber,” Advances in Concrete Construction, vol. 4, no. 6, pp. 323–344, 2018.
• [17] M. N. S. Hadi, N. A. Farhan, and M. N. Sheikh, “Design of geopolymer concrete with GGBFS at ambient curing condition using Taguchi method,” Construction and Building Materials, vol. 140, pp. 424–431, 2017.
• [18] H. S. Shiu, K. L. Lin, S. J. Chao, C. L. Hwang, and T. W. Cheng, “Effects of foam agent on characteristics of thin-film transistor liquid crystal display waste glass-metakaolin-based cellular geopolymer,” Environmental Progress and Sustainable Energy, vol. 33, no. 2, pp. 538–550, 2014.
• [19] J. G. Jang, N. K. Lee, and H. K. Lee, “Fresh and hardened properties of alkali-activated fly ash/slag pastes with superplasticizers,” Construction and Building Materials, vol. 50, pp. 169–176, 2014.
• [20] A. Onefile, “Título: The fresh and engineering properties of alkali activated slag as a function of fly ash replacement and alkali concentration Autor(es): Wei­Chien Wang, Her­Yung Wang and Ming­Hung Lo Fonte:,” Construction and Building Materials, vol. 84, pp. 1–7, 2015.
• [21] C. Ruiz-Santaquiteria, J. Skibsted, A. Fernández-Jiménez, and A. Palomo, “Alkaline solution/binder ratio as a determining factor in the alkaline activation of aluminosilicates,” Cement and Concrete Research, vol. 42, no. 9, pp. 1242–1251, 2012.
• [22] J. J. Zheng, C. Q. Li, and X. Z. Zhou, “Characterization of microstructure of interfacial transition zone in concrete,” ACI Materials Journal, vol. 102, no. 4, pp. 265–271, 2005.
• [23] ACI3636R, “Guide to Quality Control and Testing of High-Strength Concrete Reported by ACI Committee 363,” 1998.
• [24] ACI committee 318, Building Code Requirements for Structural Concrete ACI Committee 318. 2014.
• [25] Eurocode 2: Design of concrete structures, vol. 1992-1–2. 1992.
• [26] FIB Model Code, Interface Characteristics. 2013.
• [27] F. A. Oluokun, E. G. Burdette, and J. H. Deatherage, “Splitting Tensile Strength and Compressive Strength Relationships at Early Ages,” ACI Materials Journal, vol. 88, no. 2, pp. 115–121, 1991.
• [28] M. Sofi, J. S. J. van Deventer, P. A. Mendis, and G. C. Lukey, “Engineering properties of inorganic polymer concretes (IPCs),” Cement and Concrete Research, vol. 37, no. 2, pp. 251–257, 2007.
• [29] G. S. Ryu, Y. B. Lee, K. T. Koh, and Y. S. Chung, “The mechanical properties of fly ash-based geopolymer concrete with alkaline activators,” Construction and Building Materials, vol. 47, no. 2013, pp. 409–418, 2013.
• [30] N. K. Lee and H. K. Lee, “Setting and mechanical properties of alkali-activated fly ash/slag concrete manufactured at room temperature,” Construction and Building Materials, vol. 47, pp. 1201–1209, 2013.
• [31] N. Zabihi and Ö. Eren, “Compressive strength conversion factors of concrete as affected by specimen shape and size,” Research Journal of Applied Sciences, Engineering and Technology, vol. 7, no. 20, pp. 4251–4257, 2014.