Bond-Slip Behavior of Steel Bar Embedded in Lightweight Concrete Using Sand Coated Polypropylene Coarse Aggregate

Plastic waste as coarse aggregates in concrete making is part of efforts to reduce environmental pollution. In one hand the use of plastic as aggregates can provide lighter weight of concrete than those using natural aggregates. Accordingly, a comprehensive experimental study on the concrete-steel bond behavior of structural waste polypropylene (PP) lightweight coarse aggregate concrete (WPPLAC) was carried out using different composition, aggregate gradation, type of bar and size diameter of bar. Pull out tests are conducted for three kind of plain and deformed steel bars having diameter 10, 12 and 16 mm respectively, which are embedded in concrete cubes made by the two mixtures to know local bond-slip relation. Two mixtures of sand coated polypropylene (PP) coarse plastic aggregates, sand as fine aggregates, water and Portland Composite Cement with a water-cement ratio of 0.264 are conducted. The first mixture contains 100% of 25 mm sand coated coarse aggregate while the second mixture contains 70% of 25 mm and 30% of 20 mm sand coated coarse aggregates. Bond strength versus steel displacements results in general show that higher bond strength is found for steel bar having larger diameter while steel displacements approximately follow the scale of bar diameter.