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ÖzBu çalışmada, doğal anhidrit (CaSO 4 )'in beton karışımına değişik oranlarda eklenmesi ile oluşturulan beton örneklerinin fizikomekanik özellikleri değerlendirilmiştir. Hammadde olarak kullanılan doğal anhidrit Ulukışla (Niğde) bölgesinde yüzeyleyen Zeyvegediği anhidritinden; kırmataş agregası Karaisalı formasyonu (A. Miyosen) kireçtaşlarından derlenmiştir. Hazırlanan beton örnekleri tek eksenli basınç dayanımı ve ultrases hız deneylerine tabi tutulmuştur.Deney sonuçları beton karımı içinde mikronize edilmiş doğal anhidrit miktarı %27-42 aralığında iken beton dayanımının birbirine çok yakın en büyük değerlerine ulaştığını göstermektedir. Diğer taraftan %27-42 anhidrit içerik bandının dışına çıkıldığında dayanım değerleri ani olarak belirgin şekilde azalmaktadır.Beton örneklerinin ultrases hız değerleri ile doygun birim hacim ağırlıkları karşılaştırıldığında ters orantılı güçlü bir korelasyon ortaya çıkmaktadır. Bu sıra dışı durum 2,92 değerinde özgül ağırlığa sahip doğal anhidritin, beton karışımında kırmataş olarak kullanılan 2,72 özgül ağırlığındaki kireçtaşından daha küçük ultrases (UPV) değerine sahip olmasından kaynaklanmaktadır. Sonuçlar mikronize edilmiş doğal anhidritin betonda çimento gibi davranarak bağlayıcılık özelliği gösterdiğini ve belirli oranlarda kullanılması durumunda beton dayanımından önemli artışlar sağladığını ortaya koymaktadır. Anahtar kelimeler: Doğal anhidrit, Beton, Dayanım ve ultrases hızı Utilization of Natural Anhydrite as Concrete Component AbstractIn this study, the physicomechanical properties of concrete samples produced by adding of micronized natural anhydrite (CaSO 4 ) in various proportions to the concrete mix were evaluated.

This work is about the effect of fine aggregate properties on the physicomechanical characteristics of hardened mortars. The results indicated that the increase in grain-size of fine aggregate increases the bulk density of hardened mortars. The strength of mortars including limestone fine aggregate is higher than that of the silica-sand. Regardless of the aggregate origin, the strength of the mortars with well-graded fine aggregate for all grain-size is greater than of with uniform fine aggregate. This indicates that grading of fine aggregate increases the strength, while uniformity decreases it.The strength of mortars with well-graded fine aggregate increases as the grain-size increases. Regardless of the aggregate origin, the strength of mortars with uniform fine aggregate increases with increasing grain-size until the grain-size range of 425-1000 µm, but after this range it decreases with increasing grain-size. The thermal conductivity increases with the increase in the grain-size. Notedly, the relationship between thermal conductivity and maximum grain-size of well-graded fine aggregate has a very strong positive correlation. Further, the thermal conductivity value for mortars formed with uniform fine limestone aggregate is minimum at the grain-size range of 425-1000 µm, while it has greatest values close together from this grain-size range

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The effect of flakiness, one of the shape property of aggregate on concrete, is not an issue sufficiently clarified. In addition, there are no satisfactorily detailed limitations for flakiness on a global scale. This study, in which limestone was used as an aggregate, describes the dependence of flakiness on the concrete behaviour both in the fresh and hardened state. In this context, slump tests in the fresh state and compressive strength tests in the hardened state at 7, 28 and 60 days were carried out using concrete mixes prepared in the same design and with different fl akiness percentages. An increase of flaky particle fraction in coarse aggregate caused flocculation and segregation leading to the inhomogeneity of concrete mix. The slump of the mix decreased markedly as the flakiness increased, and an increase in flakiness by 25% resulted in an average reduction of 18 mm in the slump value. The test results indicated that the compressive strength of concrete decreased significantly with increasing flakiness. According to these negative linear relationships with strong correlation coefficients, an increase in the flaky coarse particles by 25% led to a decrease in compressive strength of average 0.9, 0.4 and 1.2 MPa for the curing times of 7, 28 and 60 days, respectively. Furthermore, the increase in flakiness enhanced particularly the range and standard deviation of compressive strength values with the same flakiness percentage, which this trend was most pronounced and meaningful at 60 days. This phenomenon exhibits that the differences and uncertainty in the compressive strength of the concrete specimens with the same flakiness percentage, increase distinctly with the increase in the flakiness.