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Advances in Concrete Construction
  Volume 11, Number 4, April 2021 , pages 299-306

Pozzolanic properties of trachyte and rhyolite and their effects on alkali-silica reaction
Vahiddin Alperen Baki, Safa Nay, Şakir Erdoğdu and İlker Ustabaş

    The alkali-silica reaction (ASR) is a highly complex chemical reaction which causes damage to concrete and thus adversely affects the durability and service life. Significant damage can occur in concrete structures due to cracking because of the chemical reactions taking place. Various mineral and chemical additives have been used so far to mitigate ASR and/or to reduce its adverse effects. In this study, ground trachyte and rhyolite provided from Rize-Çağrankaya region, Turkey, were used to investigate their effectiveness in controlling ASR-induced damage by substituting them with cement at certain ratios. In this context, initially the possible use of trachyte and rhyolite as pozzolanas was determined in accordance with BS EN 450-1 and TS 25 standards by considering their pozzolanic activities and then their effectiveness in mitigating the ASR was evaluated as per ASTM C 1567-13. In experimental study, blends of trachyte and rhyolite were prepared by substituting them by cement at 25%, 35%, and 50% percentage. Totally 7 mixes were prepared and three samples of 25 mm mortar bars were prepared from each batch. The length changes of the mortar bars were determined at the end of 3, 7, 14 and 28 days of exposure. SEM, along with XRD analyses were performed to examine and elementally determine the ASR products that have been formed. The results obtained have shown that ground trachyte and rhyolite used in this study can be used as pozzolanas in concrete and they can also significantly mitigate ASR-induced damage as the substitution ratio increases.
Key Words
    trachyte; rhyolite; alkali-silica reaction; pozzolanic properties; expansion
Vahiddin Alperen Baki: Department of Architecture and Civil Engineering, University of Bath, Bath, United Kingdom
Safa Nay: Department of Civil Engineering, Karadeniz Technical University, 61080, Trabzon, Turkey
Şakir Erdoğdu: Department of Civil Engineering, Karadeniz Technical University, 61080, Trabzon, Turkey
İlker Ustabaş: Department of Civil Engineering, Recep Tayyip Erdoğan University, 61080, Rize, Turkey

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