Investigation of mechanical and physical properties of cement mortar reinforced with bagasse fiber pulp and rice husk ash Atefeh Halili a.halili@cv.iut.ac.ir Date of submission: september 19, 2020 Department of Civil Engineering Isfahan University of Technology, Isfahan 84156-83111, Iran Degree: M.Sc. Language: Farsi Supervisors: Davood Mostofinejad, eft@cc.iut.ac.ir Concrete is one of the most important and common building materials in the world; Its use has been widely accepted due to its compressive strength and high durability. In contrast, the major weakness of concrete is its low tensile strength, which has led to brittleness and lack of proper ductility. By reducing environmental pollution and economic issues, use of natural fibers can be a good idea to improve the energy absorption and ductility of concrete in order to overcome the mentioned limitation. Since previous studies have shown a reduction in compressive strength of concrete containing natural fibers and degradation of plant fibers in the alkaline environment of cement, using ash as a supplementary cementing material can reduce the alkaline environment to prevent the destruction of natural fibers in the environment and also can increase the strength of the mixture due to its pozzolanic properties. Thus, the presence of natural fibers and ash from agricultural waste in concrete can improve the flexural, tensile and compressive properties of concrete. In the present study, modified bagasse fiber pulp was added to cement mortar at 0, 4 and 8% and rice husk ash was substituted for cement in cement mortar at 0, 5, 10, 15 and 20%. Compressive strength, flexural strength, direct tensile strength and hydration degree tests have been performed. In order to study the energy absorption changes of cement mortar containing bagasse pulp fibers, the strength index has been calculated. According to experimental results, adding bagasse fiber pulp to cement by up to 8% has reduced the compressive strength by about 63%; But flexural and tensile strengths have increased by about 39% and 20%, respectively. After modification of the alkaline environment of cement mortar containing bagasse pulp by rice husk ash, an improvement of about 13% was obtained for compressive strength, about 19% for flexural strength and about 34% for tensile strength compared to cement mortar containing bagasse pulp. The rise moment of flexural failure has also increased by about 49 to 222% with the addition of bagasse pulp up to 8%. In the study of flexural strength, cement mortar containing 8% bagasse pulp and 10% rice husk ash had the highest flexural strength and increased by about 461% compared to the control sample. The results show that by adding bagasse pulp and rice husk ash to the cement mortar, the degree of hydration increased and the sample containing 8% bagasse pulp and 20% rice husk ash increased the degree of hydration by about 59% compared to the control sample. Keywords Cement mortar; Bagasse fiber pulp; Rice husk ash; Mechanical properties; Degree of hydratio