Properties of self-compacting lightweight concrete reinforced with steel and polypropylene fibers

The aim of this study is to investigate the effect of incorporating steel (ST) and polypropylene (PP) fibers and silica fume on the rheological properties, mechanical properties and microstructure of self-compacting lightweight concrete (SCLC). ST fiber combined with PP fiber in four volume fractions (ST/PP = 0.5%/0, 0.5%/0.5%, 0.5%/0.75%, 0.5%/1.0%) is introduced in this study. The self-compacting characteristic of concrete is evaluated by means of slump flow, V-funnel, L-box and U-box tests. Compression, splitting tensile and flexural tests are performed to characterize the mechanical properties of SCLC. In addition, a microscopic study on the aggregates/paste and fibers/paste interfaces were conducted using Scanning Electron Microscopy (SEM). The results of the workability test show that all of the mixes can be defined as SCLC with good flowability, viscosity and passing ability. An improvement in the mechanical properties of SCLC is observed following the incorporation of silica fume and fibers. In particular, ST and PP fibers in hybrid form effectively enhance the mechanical behavior of SCLC, and result in a positive synergy. Moreover, good bond behavior at aggregates/paste and fibers/paste interfaces is observed. (C) 2019 Elsevier Ltd. All rights reserved.