Natural pozzolanas should be evaluated in terms of sustainability as well as their contribution to concrete durability. Therefore, the use of such materials in the production of cement as well as concrete industry has been gaining importance recently. In this study, the pozzolanic activities of ground trachyte and rhyolite, known as volcanic tuffs, were investigated in accordance with TS 25 standard. Pozzolanic properties of such materials, along with their pozzolanic activity indices, are investigated comparatively by the Frattini method, strength activity index, X-ray diffraction and thermogravimetric analysis. The morphologies of ground trachyte and rhyolite were also studied using SEM analysis. Based on the results obtained, the mortar samples containing blast furnace slag (BFS), fly ash (FA), trachyte and rhyolite were met the acceptable pozzolanic activity index at the end of 28 days with values of 90, 87, 89, 87, respectively. On the other hand at the end of 90 days, while the mortar samples containing BFS, FA and trachyte were met the acceptable pozzolanic activity index, that of containing rhyolite did not meet the acceptable pozzolanic activity index, with values of 93, 85, 87, 80, respectively. The pozzolanic activity index of the rhyolite was found to be quite close to that of the FA; however, the trachyte had a pozzolanic activity index close to the BFS. Comparisons of the methods implemented in the analyses were also conducted. According to the statistical evaluation of the test methods, it has been found that the relationships obtained using the direct methods as well as the indirect methods independently are highly correlated. Overall, it can be concluded that the ground trachyte may be utilized as a pozzolanas in the cement industry; however, the ground rhyolite does not meet some limits prescribed by the related standard.

中文翻译：

---

粗面岩和流纹岩的火山灰活性的测定以及所实施的测试方法的比较

应根据可持续性及其对混凝土耐久性的贡献来评估天然火山灰。因此，这种材料在水泥生产和混凝土工业中的使用最近变得越来越重要。在这项研究中，根据 TS 25 标准研究了地面粗面岩和流纹岩（称为火山凝灰岩）的火山灰活动。通过弗拉蒂尼法、强度活性指数、X 射线衍射和热重分析，对此类材料的火山灰性质及其火山灰活性指数进行了比较研究。还使用 SEM 分析研究了地面粗面岩和流纹岩的形态。根据所得结果，砂浆样品含有高炉矿渣（BFS）、粉煤灰（FA）、粗面岩和流纹岩在 28 天结束时达到可接受的火山灰活性指数，分别为 90、87、89、87。另一方面，在 90 天末，含 BFS、FA 和粗面岩的砂浆样品达到可接受的火山灰活性指数，而含有流纹岩的砂浆样品不符合可接受的火山灰活性指数，分别为 93、85、87 , 80 分别。发现流纹岩的火山灰活性指数与 FA 非常接近；然而，粗面岩的火山灰活性指数接近 BFS。还对分析中实施的方法进行了比较。根据试验方法的统计评价，已经发现，使用直接方法以及独立方法获得的关系是高度相关的。总的来说，可以得出结论，磨碎的粗面岩可以用作水泥工业中的火山灰；但是，地面流纹岩不符合相关标准规定的某些限制。