2 nd International Balkans Conference on Challenges of Civil Engineering, BCCCE, 23-25 May 2013, Epoka University, Tirana, Albania 495 Estimated the amount of air void in concrete using image processing technique Celalettin Başyiğit 1 , Bekir Çomak 2 , Şemsettin Kılınçarslan 3 1 Civil Engineering Department& Faculty of Engineering, Süleyman Demirel University, Türkiye 2 Civil Engineering Department& Faculty of Technology, Düzce University, Türkiye 3Civil Engineering Department& Faculty of Engineering Süleyman Demirel University, Türkiye Abstract Image processing methods have been widely used in civil engineering recently. Image processing is reproducing the processes people got via their own vision system by digitizing. The aim of this study is to define air void values of different concrete specifies with image processing methods. With this purpose seven different concrete series have been produced by using different water/cement rates. Physical and mechanical tests have been applied on the samples acquired. Additively air void ratios have been calculated after section images obtained from hardened concrete surfaces are processed. Relations between the results obtained as a result of image processing method and pressure resistance values of the acquired concrete samples have been examined. Consequentially it has been observed that air void values in the concrete obtained by using image processing techniques may be estimated with a high correlation. Introduction It is an inevitable factor that materials forming the concrete should have good quality, proper material rates should be used; fitting, densification and cure processes of concrete should be applied perfectly in order to obtain concrete, the most popular construction material, in a good quality. Even if concrete which is in touch with outside and has water in its voids has very good quality, it cannot show adequate resistance against iterant freezing-resolution phenomena [1]. Theoretically, minimum water amount necessary for hydration in Portland cement is approximately 25% of the cement’s weight. Added water after this process is necessary for penetrability and compressibility and adding water more than necessary reduces concrete’s quality by increasing porosity of hardened concrete. As a result additional water which is used in the concrete mixture comes up as air void in a hardened concrete [2]. Entrapped air voids are voids which are included involuntarily (by itself) in the concrete and in arbitrary forms and which range arbitrary while mixing and placing fresh concrete. Air voids entrapped in a firmly fixed concrete are generally less than 2% [3]. There may be a relation between entrapped air voids which are greater than entrained air voids. And in air contents greater than 5% in the