Nevşehir Perlit Agregasının Alkali Silika Reaksiyonu Açısından İncelenmesi

Year 2022, Volume: 14 Issue: 2, 439 - 446, 31.07.2022

Osman Şimşek İlhami Demir Ozer Sevim

https://doi.org/10.29137/umagd.1012508

Abstract

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.

Keywords

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

Investigation of Nevşehir Perlite Aggregate in Terms of Alkali Silica Reaction

Abstract

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

References

• ASTM C1260-21. (2021) Standard test method for potential alkali reactivity of aggregates (Mortar-bar method), West Conshohocken, PA: ASTM International.
• ASTM C289-07. (2007) Standard test method for potential alkali-silica reactivity of aggregates (chemical method), West Conshohocken, PA: ASTM International.
• ASTM C618-19. (2019). Standard specification for coal fly ash and raw or calcined natural pozzolan for use as a mineral admixture in concrete, West Conshohocken, PA: ASTM International.
• Bouzoubaâ, N., Zhang, M.H., & Malhotra, V.M. (2001). Mechanical properties and durability of concrete made with high-volume fly ash blended cements using a coarse fly ash, Cement and Concrete Research, 31(10), 1393–1402.
• Demir, İ., & Arslan, M. (2013). The mechanical and microstructural properties of Li2SO4, LiNO3, Li2CO3 and LiBr added mortars exposed to alkali-silica reaction, Construction and Building Materials, 42, 64–77.
• Demir, İ., & Sevim, Ö. (2017) Effect of sulfate on cement mortars containing Li2SO4, LiNO3, Li2CO3 and LiBr, Construction and Building Materials, 156, 46–55.
• Demir, İ., Sevim, Ö., & Kalkan, İ. (2018). Microstructural properties of lithium-added cement mortars subjected to alkali–silica reactions, Sadhana, 43(7), 1-10.
• Demir, İ., Sivrikaya, B., Sevim, O., & Baran, M. (2020). A study on ASR mitigation by optimized particle size distribution. Construction and Building Materials, 261, 120492.
• Esteves, T.C., Rajamma, R., Soares, D., Silva, A.S., Ferreira, V.M., & Labrincha, J.A. (2012). Use of biomass fly ash for mitigation of alkali-silica reaction of cement mortars, Construction and Building Materials, 26(1), 687–693.
• Gökçe, H.S., & Şimşek, O. (2010). Perlit agregasının pesimum reaktif agrega oranının farklı yöntemlerle incelenmesi, Gazi Üniversitesi Mühendislik Mimarlık Fakültesi Dergisi, 25(4), 839- 846.
• Hasparyk, N.P., Monteiro, P.J., & Carasek, H. (2000). Effect of silica fume and rice husk ash on alkali-silica reaction, ACI Material Journal, 97(4), 486–492.
• Massazza, F. (1993). Pozzolanic cements, Cement and Concrete Composites, 15(4), 185– 214.
• Ravina, D., & Mehta, P.K. (1986). Compressive strength of flow cement/high fly ash concrete, Cement and Concrete Research, 18, 571–583.
• Saha, A.K., Khan, M.N.N., Sarker, P.K., Shaikh, F.A., & Pramanik, A. (2018). The ASR mechanism of reactive aggregates in concrete and its mitigation by fly ash: A critical review, Construction and Building Materials, 171, 743–758.
• Sata, V. Jaturapitakkul, C., & Kiattikomol, K. (2007). Influence of pozzolan from various by-product materials on mechanical properties of high-strength concrete, Construction and Building Materials, 21(7), 1589–1598.
• Shehata, M.H., & Thomas, M.D.A. (2002). Use of ternary blends containing silica fume and fly ash to suppress expansion due to alkali–silica reaction in concrete, Cement and Concrete Research, 32(3), 341–349.
• Swamy, R.N. (1986). Cement Replacement Materials. London: Surrey University Press.
• Thomas, M., Dunster, A., Nixon, P., & Blackwell, B. (2011). Effect of fly ash on the expansion of concrete due to alkali-silica reaction – exposure site studies, Cement and Concrete Composites, 33(3), 359–367.
• Vivian, H.E. (1951). Studies in Cement-Aggregate reaction, XIX: The Effect On Mortar Expansion of the Particle Size of the Reactive Component in the Aggregate, Australian Journal of Applied Science, 2, 108-113.