Enhancing Early Strength Development of Alkali-Activated Slag through Preheating of Materials

Year 2023, Volume: 38 Issue: 4, 1129 - 1138, 28.12.2023

Cemal Karaaslan

https://doi.org/10.21605/cukurovaumfd.1410789

Abstract

Alkali-activated cements have gained attention as sustainable alternatives to Portland cement-based concretes. This study aims to enhance the early strength development of alkali-activated slag (AAS) mortars by preheating the alkali activator, ground granulated blast furnace slag, and aggregates to temperatures reaching up to 65°C before their utilization. Preheating at 50°C enhances both early and ultimate strength of AAS, compared to specimens that were not subjected to preheating. Similarly, preheating at 65°C results in a substantial increase in early strength but leads to some strength reduction after three days. SEM and FTIR analyses reveal that preheating at 50°C improves the interfacial transition zone between paste and aggregate, reduces microcracks, and promotes alkali activation. Furthermore, FTIR analysis confirms the occurrence of hydration reactions in AAS upon contact with water.

Keywords

Alkali-activated slag, Preheating of materials, Early age concrete, Heat curing, Water resistance

Malzemelerin Isıtılarak Kullanılması ile Alkali-Aktive Cürufların Erken-dönem Dayanım Gelişimlerinin İyileştirilmesi

Abstract

Alkali ile aktive edilmiş çimentolar, Portland çimentosu esaslı betonlara sürdürülebilir alternatifler olarak dikkat çekmektedir. Bu çalışmada, alkali aktivatör, öğütülmüş granüle yüksek fırın cürufu ve agreganın 65°C’ye kadar ısıtılması yoluyla alkali ile aktive edilmiş cüruf (AAS) esaslı harçların erken yaştaki dayanım gelişimlerinin iyileştirilmesi amaçlanmıştır. Ön ısıtmaya tabi tutulmayan AAS ile kıyaslandığında, 50°C’lik ön ısıtma, AAS’nin hem ilk günlerdeki hem de nihai dayanımını artırırken 65°C’lik ön ısıtma, AAS’nin ilk saatlerdeki dayanımını önemli derecede artırırken 3 günden sonraki dayanımlarda bir miktar düşüşlere sebep olmuştur. 50°C’lik ön ısıtmanın hamur ile agrega arasındaki bağı arttırdığı, mikro çatlakları azaltarak daha yoğun bir matris oluşturduğu ve alkali aktivasyonu ilerlettiği SEM ve FTIR analizlerinden anlaşılmaktadır. Ayrıca FTIR analizleri, suyla temas eden AAS’lerde hidratasyon reaksiyonlarının gerçekleştiğini göstermektedir.

Keywords

Alkali-aktive cüruf, Malzemelerin ön-ısıtılması, Erken dayanımlı betonlar, Isıl kür, Suya dayanıklılık

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