Reolojik Parametreleri Ölçülebilen Farklı C3A Oranına Sahip Hamur Karışımlarında Optimum Su Azaltıcı Katkı Dozajının ve Su Muhtevasının Belirlenmesi


Karakuzu K., Kobya V., Mardani A.

Avrupa Bilim ve Teknoloji Dergisi, vol.37, pp.17-20, 2022 (Peer-Reviewed Journal)

Abstract

C3A ratio is one of the parameters that greatly affects the rheological properties of cementitious systems. With the increase in the C3A ratio, the water reducing admixtures and/or water requirement increases to achieve the target spread. Some parameters are taken into account such as the type of rheometer, application of the method, the homogeneous preparation of the mixture and the water reducing admixture content in determining the water/cement (w/c) ratio and water reducing admixture requirement in the mixtures produced for the measurement of the rheological parameters of paste mixtures. The mixture produced should not be too solid (it may exceed the measuring capacity of the rheometer / the mixture may not be homogeneous) and excessively fluid (there may be a risk of segregation). For this reason, it is of great importance to determine the optimum water reducing admixture requirement and water/cement (w/c) ratio in mixtures where rheological measurements can be taken. In this study, optimum polycarboxylate-based water reducing admixture (PCE) dosage and w/c ratio were investigated in paste mixtures having different C3A ratios. For this purpose, CEMI 42.5R type portland cement with 4 different C3A ratios as 2%, 3%, 6% and 9% was used. A total of 80 different paste mixtures with 4 different w/c ratios (0.30, 0.32, 0.35 and 0.40) were prepared by adding PCE (0, 0.05, 0.10, 0.15 and 0.20% by weight of cement) in 5 different dosages. According to the results, it was observed that the admixture requirement and w/c ratio increased with the increase in the C3A ratio of the mixtures. On the other hand, it was determined that the segregation tendency increased with the increase of PCE dosage and w/c ratio in mixtures with low C3A ratio. As a result, the optimum PCE dosage was determined as 0%, 0.10% and 0.15% in terms of rheological parameters in paste mixtures. Also, the optimum w/c ratio was obtained between 0.32 and 0.35.