Farklı Kökenli Doğal Kumların Betonda Alkali Silis Reaksiyonu Yönünden Değerlendirilmesi

Beton üretiminde yaygınca kullanılan doğal kumlar içerdikleri minerallerin türüne göre alkali-silis reaksiyonuna neden olabilirler. Bu çalışmanın amacı, farklı kökenli kumların alkali-silis reaktivitesini karşılaştırmaktır. Örnekler; Karadeniz Kıyısı-Akpınar, Trakya-Çorlu, Muratlı ve Sinekli, İstanbul-Ömerli ve Bursa-Mustafakemalpaşa bölgelerinde bulunan yedi farklı kum ocağından alınmıştır. Kumların alkali-silis reaktiviteleri petrografik, mineralojik, kimyasal incelemeler ve hızlandırılmış harç çubuğu deneyleri ile araştırılmıştır. Yapılan değerlendirmeler sonucunda çört, kalsedon vb. aktif silis mineralleri ile metamorfik kökenli kaya parçaları içeren kumların alkali-silis reaksiyonu açısından tehlikeli olabileceği saptanmıştır

The Effect of Feldspar, Mica and Clay Minerals on Compressive Strength of Mortar

The mineralogical composition of fine aggregates plays an important role when used in mortar production because they generally effect the strength and durability of mortar structures. In this work, some mechanical aspects are highlighted concerning the use of fine aggregates containing Na-feldspar, K-feldspar, mica and some clay minerals such as kaolinite, illite and montmorillonite. With in this scope, total of there series of mortar mixtures were made with different water/cement ratio. First mixture was referance mortar prepared by using standard sand. In second mixtures, standard sand was replaced with 20 % Na-feldspar, K-feldspar and mica. Third mixtures contained 4 % of kaolinite, illite and montmorillonite as partial replacement of standard sand. According to the results obtained, addition of mica and clay minerals such as illite and montmorillonite with different percentages in standard sand causes to increase water demand in mortar and therefore reduce the strength of mortar

Evaluation of alkali reactivity of natural sands

Natural sands may lead to alkali-silica reaction in concrete when the conditions are favorable. However, natural sands vary in composition and therefore may demonstrate different reaction characteristics. The aim of this study is to compare alkali-silica reactivity of seven different natural sands with different origin. The particle size distributions for sand samples were firstly obtained by sieving method. Petrographic examinations, mineralogical and chemical analyses were firstly conducted to determine the mineralogical and chemical composition of sands. Then, accelerated mortar bar tests, ASTM C 1260, were performed. Additionally, SEM observations were conducted on the mortar bars. According to the results obtained, sands containing active silica and silicate minerals, metamorphic and volcanic rock particles are found to be potentially dangerous for alkali-silica reaction (ASR). The SEM observations have supported the expansion data. (C) 2011 Elsevier Ltd. All rights reserved

The Effect of Feldpar, Mica and Clay Minerals on Compressive Strength of Mortar

The mineralogical composition of fine aggregates plays an important role when used in mortar production because they generally effect the strength and durability of mortar structures. In this work, some mechanical aspects are highlighted concerning the use of fine aggregates containing Na-feldspar, K-feldspar, mica and some clay minerals such as kaolinite, illite and montmorillonite. With in this scope, total of there series of mortar mixtures were made with different water/cement ratio. First mixture was referance mortar prepared by using standard sand. In second mixtures, standard sand was replaced with 20 % Na-feldspar, K-feldspar and mica. Third mixtures contained 4 % of kaolinite, illite and montmorillonite as partial replacement of standard sand. According to the results obtained, addition of mica and clay minerals such as illite and montmorillonite with different percentages in standard sand causes to increase water demand in mortar and therefore reduce the strength of mortar