Investigation of Activator Type on Alkali Silica Reaction in Alkali Activated Slag Cements

Nilgün Çirkin; Serdar Aydın

Makale detayları

Investigation of Activator Type on Alkali Silica Reaction in Alkali Activated Slag Cements

Yazarlar:

Nilgün Çirkin | Serdar Aydın

Yayıncı:

Dokuz Eylul University

Ana Başlıklar:

Yapı Malzemeleri

Dergi:

Dokuz Eylül Üniversitesi Mühendislik Fakültesi Fen ve Mühendislik Dergisi Vol.27 Issue 81, pp.349-358

Belge Tipi:

Makale

Yayın Tarihi:

9/2025

Belge Dili:

Türkçe

Document ID (Org No.):

2001358746

pISSN:

1302-9304

Anahtar kelimeler:

Özet:

 The activators used in the production of alkali-activated slag AAS binders contain high amounts of alkali. Therefore, if AAS binders are used together with aggregates containing reactive silica, damage due to Alkaline Silica Reaction ASR is possible. This issue needs to be evaluated in terms of important parameters such as raw material type, activator type and dosage. In this study, the effect of activator type on ASR was investigated by determining the ASR expansions of AAS mortar mixtures produced by activating blast furnace slag with various activators using binder and reactive aggregate using ASTM C1260 Accelerated Mortar Bar method. Sodium hydroxide, sodium silicate, sodium carbonate and sodium sulfate were used as activators. Weak activators sodium carbonate and sodium sulfate were used in hybrid form with calcium hydroxide and sodium hydroxide. Expansions of Portland cement PC mortars were also investigated for comparison. It was observed that the ASR expansions of the alkali-activated slag mortars were lower compared to those of PC. Except for the specimens produced using PC, no specimen exceeded the harmful expansion limit 0.1 given in ASTM C1260 standard in the 14th day measurements. The expansion values of the samples prepared using sodium silicate activator exceeded 0.1 on day 90. The expansion amounts of the samples prepared with sodium hydroxide activator remained below 0.1. At the end of 3 months, the sodium carbonate and sodium sulfate mixtures reached approximately 3 times 0.1. This shows that the 14-day period given in ASTM C1260 standard for alkali-activated mortars is short. According to the SEM images obtained, it was observed that cracks were formed at the aggregate, matrix and matrix-aggregate interface as a result of ASR, and ASR products with needle-like morphology were formed at the aggregate-matrix interface and voids.

 The activators used in the production of alkali-activated slag AAS binders contain high amounts of alkali. Therefore, if AAS binders are used together with aggregates containing reactive silica, damage due to Alkaline Silica Reaction ASR is possible. This issue needs to be evaluated in terms of important parameters such as raw material type, activator type and dosage. In this study, the effect of activator type on ASR was investigated by determining the ASR expansions of AAS mortar mixtures produced by activating blast furnace slag with various activators using binder and reactive aggregate using ASTM C1260 Accelerated Mortar Bar method. Sodium hydroxide, sodium silicate, sodium carbonate and sodium sulfate were used as activators. Weak activators sodium carbonate and sodium sulfate were used in hybrid form with calcium hydroxide and sodium hydroxide. Expansions of Portland cement PC mortars were also investigated for comparison. It was observed that the ASR expansions of the alkali-activated slag mortars were lower compared to those of PC. Except for the specimens produced using PC, no specimen exceeded the harmful expansion limit 0.1 given in ASTM C1260 standard in the 14th day measurements. The expansion values of the samples prepared using sodium silicate activator exceeded 0.1 on day 90. The expansion amounts of the samples prepared with sodium hydroxide activator remained below 0.1. At the end of 3 months, the sodium carbonate and sodium sulfate mixtures reached approximately 3 times 0.1. This shows that the 14-day period given in ASTM C1260 standard for alkali-activated mortars is short. According to the SEM images obtained, it was observed that cracks were formed at the aggregate, matrix and matrix-aggregate interface as a result of ASR, and ASR products with needle-like morphology were formed at the aggregate-matrix interface and voids.

 The activators used in the production of alkali-activated slag AAS binders contain high amounts of alkali. Therefore, if AAS binders are used together with aggregates containing reactive silica, damage due to Alkaline Silica Reaction ASR is possible. This issue needs to be evaluated in terms of important parameters such as raw material type, activator type and dosage. In this study, the effect of activator type on ASR was investigated by determining the ASR expansions of AAS mortar mixtures produced by activating blast furnace slag with various activators using binder and reactive aggregate using ASTM C1260 Accelerated Mortar Bar method. Sodium hydroxide, sodium silicate, sodium carbonate and sodium sulfate were used as activators. Weak activators sodium carbonate and sodium sulfate were used in hybrid form with calcium hydroxide and sodium hydroxide. Expansions of Portland cement PC mortars were also investigated for comparison. It was observed that the ASR expansions of the alkali-activated slag mortars were lower compared to those of PC. Except for the specimens produced using PC, no specimen exceeded the harmful expansion limit 0.1 given in ASTM C1260 standard in the 14th day measurements. The expansion values of the samples prepared using sodium silicate activator exceeded 0.1 on day 90. The expansion amounts of the samples prepared with sodium hydroxide activator remained below 0.1. At the end of 3 months, the sodium carbonate and sodium sulfate mixtures reached approximately 3 times 0.1. This shows that the 14-day period given in ASTM C1260 standard for alkali-activated mortars is short. According to the SEM images obtained, it was observed that cracks were formed at the aggregate, matrix and matrix-aggregate interface as a result of ASR, and ASR products with needle-like morphology were formed at the aggregate-matrix interface and voids.

 Alkali ile aktifleştirilmiş cüruf AAS bağlayıcılarının üretiminde kullanılan aktivatörler yüksek miktarda alkali içermektedir. Bu sebeple, AAS bağlayıcılarının reaktif silis içeren agregalar ile birlikte kullanımı halinde Alkali Silika Reaksiyonu ASR kaynaklı hasar oluşma mevcuttur. Bu konunun; hammadde türü, aktivatör türü ve dozajı gibi önemli parametreler bakımından değerlendirilmesi gerekmektedir. Bu çalışmada, yüksek fırın cürufunun çeşitli aktivatörler ile aktive edilmesiyle üretilen bağlayıcı madde ve reaktif agrega kullanılarak üretilen AAS harç karışımlarının ASTM C1260 Hızlandırılmış Harç Çubuğu yöntemiyle ASR genleşmeleri belirlenerek, aktivatör tipinin ASR üzerindeki etkisi araştırılmıştır. Aktivatör olarak, sodyum hidroksit, sodyum silikat, sodyum karbonat ve sodyum sülfat kullanılmıştır. Zayıf aktivatörler sodyum karbonat ve sodyum sülfat; kalsiyum hidroksit ve sodyum hidroksit ile hibrit şekilde kullanılmıştır. Ayrıca, kıyaslama yapabilmek için Portland çimentosu PÇ harçlarının da genleşmeleri incelenmiştir. PÇ ile kıyaslandığında alkalilerle aktive edilmiş cüruf harçlarının ASR genleşmelerinin daha düşük olduğu görülmüştür. PÇ kullanılarak üretilen numuneler dışında 14. gün ölçümlerinde ASTM C1260 standardında verilen zararlı genleşme limitini 0,1 geçen numune olmamıştır. Sodyum silikat aktivatörü kullanılarak hazırlanan numunelerinin genleşme değerleri 90. günde 0,1i aşmıştır. Sodyum hidroksit aktivatörü ile hazırlanan numunelerin genleşme miktarları 0,1in altında kalmıştır. 3 ayın sonundaki ölçümlerde sodyum karbonatlı ve sodyum sülfatlı karışımlar 0,1in yaklaşık 3 katına ulaşmıştır. Bu durum alkalilerle aktive edilmiş harçlar için ASTM C1260 standardında verilen 14 günlük sürenin kısa olduğunu göstermektedir. Elde edilen SEM görüntülerine göre ASR sonucu agrega, matris ve matris-agrega ara yüzeyinde çatlakların oluştuğu, agrega-matris arayüzeyinde ve boşluklarda iğnemsi morfolojiye sahip ASR ürünlerinin oluştuğu görülmüştür.

Makale detayları

Investigation of Activator Type on Alkali Silica Reaction in Alkali Activated Slag Cements

Yazarlar:

Nilgün Çirkin | Serdar Aydın

Yayıncı:

Dokuz Eylul University

Ana Başlıklar:

Yapı Malzemeleri

Dergi:

Dokuz Eylül Üniversitesi Mühendislik Fakültesi Fen ve Mühendislik Dergisi Vol.27 Issue 81, pp.349-358

Belge Tipi:

Makale

Yayın Tarihi:

9/2025

Belge Dili:

Türkçe

Document ID (Org No.):

2001358746

pISSN:

1302-9304

Alkaline Activated Slag Mortars(AAS)

Alkaline Silica Reaction (ASR)

Alkaline Activators

ASTM C1260Anahtar Kelimeler: Alkali Aktive Cüruf Harçlar (AAS)

Alkali Silika Reaksiyonu (ASR)

Alkali Aktivatörler

ASTM C1260

Sayı

Makale detayları

Yazarlar: Nilgün Çirkin | Serdar Aydın

Yayıncı: Dokuz Eylul University

Ana Başlıklar: Yapı Malzemeleri

Dergi: Dokuz Eylül Üniversitesi Mühendislik Fakültesi Fen ve Mühendislik Dergisi Vol.27 Issue 81, pp.349-358

Belge Tipi: Makale

Yayın Tarihi: 9/2025

Belge Dili: Türkçe

Document ID (Org No.): 2001358746

pISSN: 1302-9304

Sayı

Yazarlar:

Nilgün Çirkin | Serdar Aydın

Yayıncı:

Dokuz Eylul University

Ana Başlıklar:

Yapı Malzemeleri

Dergi:

Dokuz Eylül Üniversitesi Mühendislik Fakültesi Fen ve Mühendislik Dergisi Vol.27 Issue 81, pp.349-358

Belge Tipi:

Makale

Yayın Tarihi:

9/2025

Belge Dili:

Türkçe

Document ID (Org No.):

2001358746

pISSN:

1302-9304