بررسی پتانسیل واکنش قلیایی سیلیسی مصالح سنگی مورد استفاده در بتن در مناطق جنوبی استان سیستان و بلوچستان

abstract in aggregate, active forms of reactive silica with mineral names are sometimes associated with sand and gravel in concrete mixture. alkali hydroxides originated from alkalis in the cement or other resources form an alkaline silica gel with this reactive silica which becomes swallowed and expanded during time causing damage to concrete. there have been growing researches on alkaline reactions of aggregates in concrete structure in order to augment health coefficient of concrete structures and to prevent and reduce repair and replacement costs. the most common damage caused by alkaline reaction begins from surface cracks which become bigger in width direction and workshop repairing is often failed. reports of many international conferences held in different countries in the past years indicate the risk of global distribution of alkaline reaction in concrete structures. different forms of alkaline reactions caused damages to structures and it is common in tropical climates. for concrete structures specially the ones exposed to the conditions conductive to alkali reaction of aggregates (active aggregates, high alkaline and humidity) it is necessary to determine reactivity potential of aggregates. so before providing concrete mix design, the ability of alkaline reaction of aggregates should be investigated by catalyzed chemical tests considering aggregates in the region. domestic researches conducted are very rare especially in sistan and baluchestan which is performed for the first time. the present research can bring innovations about proposing appropriate mines of aggregates used in concrete. another implication is that if it is necessary to use potential active aggregates for some reasons (such as financial limitations, workshop location…), prevention measures should be considered to prevent alkaline reaction of aggregates. such measures are assessed beforehand in a lab to determine their effect on preventing the progress of aggregates alkaline reaction. considering hot and humid climate of the province of sistan and baluchestan and conducting several international projects in the region, aggregates of eight active mines in the region which are widely used were sampled. the chemical test astmc289 was used in order to determine silica alkaline reaction indicating non-reactivity of aggregates. the results were used to provide concrete durability and select appropriate mines of aggregates.