Investigation of asr effect in intermediate aggregates in the north of Van province

Alkali silica reactivity (ASR) is a complex chemical reaction that significantly effects the durability of concrete structures. It is possible to encounter ASR damage in reinforced concrete structures in our country and in many parts of the world. The work to be done in this resarch area is important to avoid the ASR damage. In this study, alkali silica reactivity properties of trachyte, tracyandesite and pumice aggregates in the North of Van province were investigated. To determine the alkali silica reactivity, accelerated mortar bar method and chemical method experiments were carried out on the samples. Instead of trachyte and trachyandesite, 10%, 20%, 30% pumice were replaced respectively and 32 mortar bars were prepared for the accelerated mortar bar test. Also, instead of cement, 30% pumice was replaced 6 mortar bar were prepared for accelereted mortar bar method. A total of 38 mortar bars were produced for the accelerated mortar bar method. The 3, 7, 14, 28 and 56 day length changes were measured according to the accelerated mortar bar method. In order to determine the ASR by chemical method, 3 samples of 25 gr aggregate, which is 0.250mm and 0.125mm in the range of sieve, were prepared. SEM analyzes were performed on the samples to see the difference between the mortar bar samples before and after the experiment. Some differences were observed in the SEM images obtained before and after the accelerated mortar bar method. As a result, according to the accelerated mortar bar mehod, it has been concluded that the expansion rates of trachyte and trachyandesite aggregates are larger than 0.2% and they are in the class of harmful aggregates. It was observed that instead of trachyte and trachyandesite, 20% and 30% by weight of pumice additions reduced the ASR effects. It was observed the instead of cement 30% by weight of pumice additions as a binder was reduced ASR effects. According to the result of the chemical analysis, pumice, trachyte and trachyandesite aggregates are classified as "harmfull aggregates" in terms of alkali silica reactivity as specified in ASTM C 289 standard III. is located within the region.