نوع مقاله : مقاله پژوهشی
استادیار، مرکز تحقیقات راه مسکن و شهرسازی، تهران، ایران
عنوان مقاله [English]
The aggregates as a prominent part of concrete mixture have significant impact on durability and strength of concrete pavements. One of the most important problems attributed to some part of aggregates in Iran are reported to possibly deleterious alkali silica reaction between the hydroxyl ions (OH−) in the pore solution and reactive silica in the aggregate over the time. So, investigation of alkali-silica reaction potential for aggregate in this area in addition to identifying appropriate preventive measures to minimize the risk of expansion is so invaluable because of high consumption of these suspicious materials in the construction of concrete pavements.
This study presents evaluation of alkali silica reactivity potential of Mazandaran and Guilan aggregates using petrography examination of aggregate according to ASTM C295, alkali silica reactivity mortar bar testing according to ASTM C1260 and determination of length change of concrete due to alkali silica reaction according to ASTM C1293. Selecting appropriate preventive measures to minimize the risk of expansion when deleterious reactive aggregates are used in concrete pavements are described in following. Based on results obtained in present study, it was observed that about 30 and 50 percentages of aggregates placed in two studied province of Mazandaran and Gilan respectively, has high alkali silica reactivity. Furthermore, preventive measures including limiting the alkali loading of the concrete to 1.8 kg/m3, substitution supplementary cementitious materials such as silica fume to amount of 7%, or a combination of these strategies was suggested for use of high alkali silica reactivity aggregates in concrete pavements.