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

Year 2019, Volume: 4 Issue: 2, 89 - 100, 05.08.2019

Hayder Alı , Nildem Tayşi

Abstract

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.

Keywords

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

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

Abstract

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.

Keywords

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

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