چكيده به لاتين
Abstract
Nowadays, lightweight concrete has found a lot of application in the buildings due to reduced dead load and low cost of construction. One of the methods for reducing the weight of concrete is replacement of sand with expanded polystyrene beads. In this research, recycled expanded polystyrene beads (EPS) in two types with diameters of 3-6 (type I) and 0-3 (type II) mm, and thermal modified expanded polystyrene beads (MEPS) with diameters of 0-3 mm, and surface functionalized EPS and MEPS for decreasing the concrete density, and silica fume to improve concrete compressive strength and reduce its water absorption (due to the covalent bonding caused by the reaction with water and cement) have been used. Since incorporation of EPS beads at different replavement levels resulted in significant losses (60 – 98%) in concrete compressive strengths at different curing ages due to its poor mechanical properties, low density, and inefficient compaction that leads to loss of concrete integrity, attempte were made to modify the microstructure of EPS (by thermal treatment) and improve its surface properties (by acid treatment) to avoid loss of concrete compressive strength as much as possible. Based on the obtained results, use of MEPS compared to EPS increased the compressive strength of lightweight concrete by about 12% - 40%. The use of surface functionalized EPS and MEPS at the replacement levels of 25%, 50%, 75% and 100% resulted in a significant increases (5% -25%) in compressive strength compared to the corresponding lightweight concretes incorporating EPS and MEPS at same density and replacement level.
Keywords: Light Weight Concrete, Expanded Polystyrene, Modified Expanded Polystyrene
