عنوان مقاله [English]
The idea of using paper wastes in concrete to reduce environmental pollution and Silica fume to improve the properties of concrete is a huge transformation in the building industry. In this study, the effect of waste paper ash along with silica fume on mechanical properties of concrete was investigated experimentally. The cement was replaced with different percentages of paper waste ash (0, 2.5, 5, 7.5, and 10%) and Silica fume (0, 2.5, 5, 7.5, and 10%). Then, 25 mix designs were prepared. Compressive strength, indirect tensile strength, flexural tensile strength, slump, ultrasonic pulse velocity, and impact tests are performed for all concrete specimens at different ages. Also, creep was presented for concrete-containing waste paper ash and silica fume based on existing equations and they were compared with the concrete code of USA and concrete code of Iran. These equations were suggested to predict the behavior of concrete-containing waste paper ash and silica fume. It was also observed that at a constant water cement ratio and for all ages, Silica fume and paper waste ash increased. Also, based on the results of this study, empirical relationships were presented for the relationship among indirect tensile strength and 28-days compressive strength of concrete, tensile strength due to flexural and 28-day compressive strength of concrete specimens, compressive strength and specific weight. Thus, these equations could be used to predict the behavior of concrete-containing paper waste ash and Silica fume. The tensile strength/compressive strength ratio of ordinary concrete was about 10. However, this ratio was between 13.55 and 17.79 in concrete specimens containing waste paper ash and silica fume. The compressive strength ratio of 28 days to 90 days was between 0.67 and 0.81. However, this ratio was between 0.55 and 0.65 in ordinary concrete, which indicates the higher initial strength of specimens containing waste paper ash and silica fume.