Assessment of the potential alkali-reactivity of aggregates for concrete by image analysis petrography

Application of Image Analysis to Identify Quartz Grains in Heavy Aggregates Susceptible to ASR in Radiation Shielding Concrete

“…The distribution of quartz grain size was evaluated using the size categories. It is known that aggregates containing quartz with a small grain size will be more prone to develop deleterious ASR due to an increase in available surface, provided that the increased surface is sufficiently accessible for the pore solution [ 11 , 12 , 30 ]. When the petrographic texture of a rock is studied, the term microcrystalline is applied to a texture so fine-grained that a petrographic microscope is needed to resolve individual crystals (4–62 μm).…”

“…Different approaches, including petrographic study, chemical tests, dilatometric evaluation, and accelerated and long-term laboratory tests are used to evaluate the ASR potential of aggregates [ 10 , 11 , 12 , 13 , 14 ]. Since the early work by Stanton [ 15 ], numerous investigations have been conducted in order to design a quick and reliable method to establish the susceptibility of some rocks to developing alkali-aggregate reactions [ 16 ].…”

“…Thin section analysis is recommended as a routine part of the petrographic examination of aggregates [ 12 , 27 ], usually performed as the essential first stage in the classification of the alkali-reactivity potential of concrete aggregates. The use of image analysis is currently limited to rock types with grain sizes resoluble under the optical microscope and to quartz grains without a high degree of strain [ 11 ]. The advantage of image analysis in comparison to the traditional point-counting method can be the speed.…”

“…The point-counting method proposed by Wigum [ 28 ] would take several hours to assess ~200 quartz grains. With the image analysis method used in [ 11 ], the assessment of up to 27,606 quartz grains was possible during 10 to 120 minutes. It was found that petrographic image analysis allows the assessment of a higher number of quartz grains in a shorter time without compromising the precision of the results.…”

Bazalt ve Atık Cam Agregalı Betonlarda Alkali-Silis Reaksiyonu Genleşmeleri ve Alkali Sızıntısı Seviyeleri

“…gibi bazı silisli mineraller nedeniyle meydana gelmektedir. Higroskopik yapıdaki alkali-silis jelinin oluşumu ile çok fazla miktarda su emilmesi ve şişme olayı, betonun çekme dayanımı aşıldığında hasara yol açmaktadır [1][2][3].…”