Nevşehir Perlit Agregasının Alkali Silika Reaksiyonu Açısından İncelenmesi

Alkali silika reaksiyonu (ASR) günümüzde betonarme elemanlarının dayanıklılığını olumsuz etkileyen oldukça karmaşık kimyasal reaksiyondur. Çimento içerisinde bulunan alkaliler ve agrega içerisinde bulunan reaktif silis miktarının bir araya gelmesi sonucu yeterli nem miktarına ulaştığında beton içerisindeki boşluklarda alkali silika jeli oluşur. Bu oluşum ile alkali silika reaksiyonu başlar. Alkali silika jellerinin su emmeleri sonucunda beton içsel gerilmeleri artar ve betonda kılcal çatlaklar meydana getirerek hasara yol açar. Bu çalışmada, Nevşehir bölgesinden elde edilen perlit agregasının alkali silika reaksiyonuna etkisi incelenmiştir. Bu kapsamda, hızlandırılmış harç çubuk deneyi (ASTM C 1260) metodu deneyleri yapılmıştır. Kırma kireçtaşı agregasına perlit agregası ağırlıkça %0, 10, 20, 30, 40, 50, 60 ve 70 oranlarında yer değiştirilmesi ile karışımlar hazırlanmıştır. Bu numuneler 7, 14 ve 28 günlük boy değişim değerleri ölçülmüştür. Harç çubuklarına Kireçtaşı agregası yerine ikame edilen perlitin alkali silika reaksiyonunu arttırdığı görülmüştür.

Anahtar Kelimeler:

Alkali silika reaksiyonu, perlit agregası, hızlandırılmış harç çubuğu metodu, boy değişim

Investigation of Nevşehir Perlite Aggregate in Terms of Alkali Silica Reaction

The alkali silica reaction (ASR) is a highly complex chemical reaction that adversely affects the durability of reinforced concrete elements today. Alkaline silica gel is formed in the pores in the concrete when sufficient moisture is reached as a result of the combination of the alkalis in the cement and the amount of reactive silica in the aggregate. With this formation, alkali silica reaction begins. As a result of the water absorption of alkali silica gels, the internal stresses of the concrete increase and it causes damage by creating capillary cracks in the concrete. In this study, the effect of perlite aggregate obtained from Nevşehir region on alkali silica reaction was investigated. In this regard, accelerated mortar bar test (ASTM C 1260) method was carried out. Mixtures were prepared by replacing the crushed limestone aggregate with the perlite aggregate at 0, 10, 20, 30, 40, 50, 60 and 70 wt.% ratios. The length change values of these samples at 7, 14 and 28 days were measured. It was observed that the perlite aggregate substituted for the limestone aggregate in the mortar bars increased the alkali silica reaction.

Keywords:

Alkali silica reaction, perlite aggregate, accelerated mortar bar test method, The length changes,

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