Mechanical and Flexural Behavior of Self Compacting Lightweight Concrete Containing Waste Plastic Fibers

Abstract

Self-compacting concrete (SCC) is any concrete material that can take form/shape without being mechanically aided, hence, SCC can be referred to as a ‘smart concrete’ material. The characteristics of SCC mix is highly influenced by the characteristics and proportions of the constituents. Therefore, it is important to find the right procedure for mixing the constituents of SCC. Similarly, Self-compacting lightweight Concrete (SCLWC) utilization is gaining more attention among researchers. Several studies have been conducted over the years on the utilization of lightweight aggregates (LWA) in SCC. Being that SCLWC is produced from renewable aggregates, it has a high chance of becoming an alternative material to the conventional concrete in the future. In this study, extensive research was conducted to develop SCLWC mixtures using locally-sourced waste materials such as Expanded Polystyrene Beads (EPS) and Waste Plastic Fibers (WPFs) which are all abundantly available in Republic of Iraq as Muncipal waste material which produce daily consumption. The fresh, hardened, mechanical, and bending behavior properties of these SCLWC were studied, followed by detailed results analysis. Six mixes of SCLWC were used in this investigation; One Ordinary Self-Compacting Concrete concrete (R mix) made of EPS content as a replacement of coarse aggregate, Six SCLWC mixtures made of EPS content as a replacement of coarse aggregate, and a different Volumetric ratio of WPFs (0, 0.25, 0.5, 0.75, 1.0, and 1.25 %) content. Also, the flexural behavior of SCLWC beams were investigated. The beams were made from same waste materials with three different reinforced bars (Ø12, Ø10, and Ø8) and denoted as Group A, Group B, and Group C, respectively. In the first part of the experiment, the fresh properties of SCLWC such as slump flow, T500, v-funel and L-Box were examined with the presence of various ratios of WPFs. The second part was transacting on the hardened properties of SCLWC mixes such as compressive strength, flexural strength, modulus of elasticity, flexural toughness, dry density, water absorption, voids content, thermal conductivity, scanning electron microscopy, and ultrasonic pulse velocity test. Adding WPFs showed slight improvement of the hardened and mechanical III properties of SCLWC. The final part of the experiment showed similar flexural behavior compared to the formation of crack patterns and width in addition to ductility index of all grouped beams. SCLWC beams showed lower post-cracking flexural resistance. Ultimate deflection of SCLWC beams increased with increasing amount of WPFs. Finally, the study showed that the density and thermal conductivity of SCLWC produced with these waste materials were decreased (29-38%)and (32–58%) respectively, lower than control specimen (R). due to the presence of EPS. The increase in WPFs content decreased the workability due to clumping that occurred in the mixing phase. The analysis of the SCLWC specimens showed that improvement in the mechanical properties Compressive Strength and Flexural Strength 25%and 33% respectively with fiber percentage of 1%. While SCLWC with 1 % WPFs provides the best flexural toughness performance. The results of flexural SCLWC beams for all groups showed typical structural behavior in flexure.