Mechanical, Pore Structure and Microstructural Properties of Alkali-Activated Fly Ash Mortars Containing Silica Aerogel

Abstract

Inclusion of silica aerogels in cement matrix can lead to an enhancement in thermal and acoustic properties of cement – based materials due to the high porosity values of silica aerogel particles. Despite their high porosity values, silica aerogel particles can also show sufficient mechanical performance under stress. In this study, mechanical, pore structure and microstructure properties of alkali – activated fly ash mortars containing a small amount of silica aerogel powder (0.25% and 0.50% of binder, by weight) were investigated. The results obtained from the experimental study reveal that the compressive toughness and compressive post-peak toughness capacities of fly ash mortars with an average compressive strength of 20 MPa could increase by about 27% and 70%, respectively. Toughness development obtained via the change in the micro and capillary pore formation in the pore structure of the mortar samples presents an innovative design idea for the production of silica aerogel-incorporated mortar blocks with improved deformation behavior under equivalent compressive stress.

Keywords

• Silica Aerogel
• Fly Ash
• Alkali-Activated Mortar
• Toughness
• Porosity

Silika Aerojel katkılı Alkali-Aktive Edilmiş Uçucu Kül Harçlarının Mekanik, Por Yapısı ve Mikro Yapı Özellikleri

Abstract

Silika aerojeller, çimento matrisine dâhil edildiklerinde yüksek poroziteleri aracılığıyla çimento esaslı malzemelerin akustik ve termal yalıtım performanslarına katkı sunabilmektedirler. Silika aerojel partikülleri, yüksek porozitelerine rağmen mekanik zorlamalar altında ihmal edilemeyecek düzeyde mekanik özellikler de gösterebilmektedirler. Bu çalışmada çimento ağırlığınca düşük katkı oranlarında (%0.25 ve %0.50) çimento matrisine dâhil edilen silika aerojellerin alkali – aktive edilmiş uçucu kül harçlarının mekanik, por yapısı ve mikro yapı özelliklerine olan etkisi araştırılmıştır. Deneysel çalışmadan elde edilen sonuçlar, ortalama 20 MPa basınç dayanımına sahip uçucu kül harçlarının basınç etkisi altındaki tokluk ve pik – sonrası tokluk kapasitelerinin sırasıyla yaklaşık %27 ve %70 düzeylerinde artabileceğini ortaya koymaktadır. Harç numunelerinin por yapısında mikro ve kapiler boyuttaki por çaplarının değişimine bağlı olarak elde edilen tokluk kazancı, gelecekte eşdeğer basınç dayanımları altında deformasyon davranışı geliştirilmiş silika aerojel katkılı blok elemanların üretimi için yenilikçi bir tasarım fikrini ortaya koymaktadır.

Keywords

• Silika Aerojel
• Uçucu Kül
• Alkali-aktive Edilmiş Harç
• Tokluk
• Porozite

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