Valorisation of waste expanded polystyrene in concrete using a novel recycling technique

Abstract

This study examines the engineering properties of lightweight aggregate concretes (LWACs) incorporating a novel Expanded Polystyrene (EPS)-based lightweight aggregated called Stabilised Polystyrene (SPS). The SPS aggregate was produced by 80% waste EPS, 10% clay and 10% cement. The influence of the increasing incorporation of SPS on the workability, density, compressive strength, flexural strength, ultrasonic pulse velocity, drying shrinkage, expansion and water absorption (WA) of the different concretes has been investigated. The results showed that the use of SPS enabled to reduce the density of concrete by 8–52% compared to that of the control concrete. The reduction in density was due to the increase in total porosity in the lightweight concretes (LWCs), which also induced higher WA, drying shrinkage and expansion. The 28-day compressive strength of the LWAC was in the range of 4.6–16.4 MPa; thus, the concrete mixture with the higher performances almost satisfied the mechanical and density criteria of structural LWC. These results show that the utilisation of SPS for the manufacture of LWACs is possible

Combined Effects of Densified Polystyrene and Unprocessed Fly Ash on Concrete Engineering Properties

“…As the adhesion between EPS and the cement paste decreasing, the strength is decreasing as well. In the case of SPS in the present work, due to the coating of EPS with clay and cement the strength is higher than unmodified EPS particles [12]. It is well known that the density of concrete has a significant influence on the strength.…”

“…The density values in Figure 5, shows that the density of concretes decreased with increasing in SPS contents in concrete [12]. This is because the density of SPS aggregates was much less than that of natural aggregates (Table 2).…”

“…In order to achieve a uniform dispersion of the EPS particles in concrete, a new recycling technique has been used [12]. The waste EPS crushed into different sizes (gravel-and sand-sized EPS beads of 2-6 mm mean diameter, angular in shape with an average density of 30 kg/m 3 ) then mixed with the paste made from red clay, cement, and water, then formed into a palm-sized "cake", which was then dried in the controlled laboratory environment of 20 ± 2 • C and between 60% to 70% relative humidity (RH) for 14 days.…”

“…Therefore, it can be partially replaced with natural coarse and/or fine aggregates to produce lightweight aggregate concrete (LWAC). LWAC is an important material in reducing the dead-weight of concrete complying with special concrete structures of high-rise buildings [3][4][5][6][7][8][9][10][11][12].…”

“…Most research [3][4][5][6][7][8][9][10][11][12] on concrete containing unmodified expanded polystyrene (EPS) has revealed a decrease in the durability and mechanical properties of concrete with increasing the amount of EPS particles in concrete. These studies have also shown that an increase in strength can be obtained with smaller EPS bead size in concrete.…”