Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 55 12 2024 02 20 An Experimental Investigation into the Mechanical Performance and Microstructure of Cementitious Mortars Containing Recycled Waste Materials Subjected to Various Environments An Experimental Investigation into the Mechanical Performance and Microstructure of Cementitious Mortars Containing Recycled Waste Materials Subjected to Various Environments 2365 2404 5271 10.22060/ceej.2023.21291.7677 FA Javad Mohseni Pour Asl MSc, Semnan University, Semnan, Iran. Majid Gholhaki Professor,, Civil Faculty, Semnan University, 0000-0002-9904-8623 Mohammad Kazem Sharbatdar Semnan University 0000-0001-6106-1235 Journal Article 2022 04 13 This paper deals with an experimental investigation into the mechanical performance and microstructure characteristics of cementitious mortars containing recycled waste materials subjected to acidic, neutral, and alkaline environments. The recycled waste materials include glass, eggshell, iron, and rubber powder in various amounts, namely 7, 14, and 21% by volume, as the replacement for ordinary Portland cement (OPC). In this respect, to examine the mechanical performance of the specimens, the compressive, tensile, and bending strength tests as well as water absorption tests were carried out at the ages of 7, 28, and 90 days. Moreover, to study the microstructure of the specimens, scanning electron microscopy (SEM) and x-ray diffraction (XRD) tests were conducted accordingly. For curing the specimens, three different environments with PH values of 2.5, 12.5, and 7 representing the acidic, alkaline, and neutral environments, were taken into account. Promisingly, it was observed that the inclusion of recycled waste materials significantly enhanced the mechanical properties of the mortar when exposed to acidic curing conditions. Lastly, the results derived from the microstructure tests revealed that as a result of replacing cement with glass, iron, and eggshell powders, the width of cracks and volume of the pores decreased by three times, and importantly, the bonding between the cement paste and additives was strengthened.     This paper deals with an experimental investigation into the mechanical performance and microstructure characteristics of cementitious mortars containing recycled waste materials subjected to acidic, neutral, and alkaline environments. The recycled waste materials include glass, eggshell, iron, and rubber powder in various amounts, namely 7, 14, and 21% by volume, as the replacement for ordinary Portland cement (OPC). In this respect, to examine the mechanical performance of the specimens, the compressive, tensile, and bending strength tests as well as water absorption tests were carried out at the ages of 7, 28, and 90 days. Moreover, to study the microstructure of the specimens, scanning electron microscopy (SEM) and x-ray diffraction (XRD) tests were conducted accordingly. For curing the specimens, three different environments with PH values of 2.5, 12.5, and 7 representing the acidic, alkaline, and neutral environments, were taken into account. Promisingly, it was observed that the inclusion of recycled waste materials significantly enhanced the mechanical properties of the mortar when exposed to acidic curing conditions. Lastly, the results derived from the microstructure tests revealed that as a result of replacing cement with glass, iron, and eggshell powders, the width of cracks and volume of the pores decreased by three times, and importantly, the bonding between the cement paste and additives was strengthened.     https://ceej.aut.ac.ir/article_5271_08aac6ac98e59e523995c161e57875f5.pdf