Mechanical Properties of Fly Ash and Blast Furnace Slag Based Geopolymer Mortars in Thermal Curing Environment

Abstract

As a result of the clinker production of cement, CO2 emission, which harms the nature and causes global warming, occurs. For this reason, studies continue on the production of geopolymer mortar by using mineral additives instead of Portland cement in order to reduce CO2 emissions. In this study, 4M, 8M, 12M NaOH and Na2SiO3 (Sodium Silicate) were used as alkali activators. The ratio of Na2SiO3/NaOH was determined as 2 and kept constant in all experimental series. By producing blast furnace slag, fly ash and 50% hybrid geopolymer mortars from both, curing was carried out in the oven bag at 50 ℃, 75 ℃, 100 ℃ for 12 hours. In order to determine the mechanical properties of the samples after curing, tensile and compressive strength in bending and Scanning Electron Microscope (SEM) tests were carried out for microstructure analysis. According to the results obtained, the compressive strength for all samples provided the best performance at 100 ℃. The average bending tensile strength of the samples produced with 4M NaOH, Na2SiO3 and blast furnace slag was 5.4 MPa and the compressive strength was 60.05 MPa. It has been observed that the compressive and bending tensile strengths of the samples produced with fly ash are quite low compared to the blast furnace slag.

Keywords

• Geopolymer
• blast furnace slag
• fly ash
• sodium silicate
• sodium hydroxide

Uçucu Kül ve Yüksek Fırın Cüruf Esaslı Geopolimer Harçların Isıl Kür Ortamında Mekanik Özellikleri

Abstract

Çimentonun klinkeri üretimi sonucu, doğaya zarar veren ve küresel ısınmaya neden olan CO2 salınımı oluşmaktadır. Bu sebeple CO2 salınımını azaltmak için portland çimentosu yerine mineral katkı malzemeleri kullanılarak geopolimer harç üretimi üzerindeki çalışmalar devam etmektedir. Bu çalışmada alkali aktivatör olarak 4M, 8M, 12M NaOH ve Na2SiO3 (Sodyum Silikat) kullanılmıştır. Na2SiO3/NaOH oranı 2 olarak belirlenip bütün deney serilerinde sabit tutulmuştur. Yüksek fırın cürufu, uçucu kül ve her ikisinden %50 oranında hibrit geopolimer harçlar üretilerek 12 saat süresince fırın torbası içerisinde 50 ℃, 75℃, 100℃ etüvde kür uygulaması yapılmıştır. Kür uygulaması sonucunda mekanik özelliklerini belirlemek için numunelerin eğilmede çekme ve basınç dayanımı, mikroyapı analizleri için ise Taramalı Elektron Mikroskobu (SEM) deneyleri yapılmıştır. Elde edilen sonuçlara göre bütün numuneler için basınç dayanımı 100 ℃’de en iyi performansı sağlamıştır. 4M NaOH, Na2SiO3 ve yüksek fırın cürufu ile üretilen numunelerin ortalama eğilmede çekme dayanımı 5,4 MPa ve basınç dayanımı 60.05 MPa sonuçları elde edilmiştir. Uçucu kül ile üretilen numunelerde basınç ve eğilmede çekme dayanımları yüksek fırın cürufuna göre oldukça düşük olduğu görülmüştür.

Keywords

• Geopolimer
• Yüksek Fırın Cürufu
• Uçucu Kül

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