Mechanical and shrinkage performance of steel fiber reinforced high strength self-compacting lightweight concrete

This study investigated the effects of mixture proportion on the mechanical and shrinkage behaviors of steel fiber reinforced high strength self-compacting lightweight concrete (SHSLC) mixtures incorporating bottom ash aggregates for internal curing. In this study, different types of fine aggregates, fine aggregate ratios, supplementary materials such as silica fume (SF) and colloidal nano-silica (CNS), and four types of steel fibers were considered to develop SHSLC. The self-compacting characteristics of concrete were evaluated by means of slump flow, J-ring flow, and V-funnel tests. The test results indicate that incorporation of SF and CNS had a positive effect on the mechanical properties, but 4% incorporation of CNS decreased workability and strength due to the agglomeration of mixture. The addition of steel fibers improved compressive strength, and flexural toughness of SHSLC, but reduced the flowability and passing ability with increased fiber contents. Due to the internal curing from coarse bottom ash, significant reduction of autogenous shrinkage up to 33% was observed, whereas 7% for drying shrinkage. The incorporation of fibers reduced the autogenous and drying shrinkage up to 31% and 22% compared with non-fiber reinforced concrete, respectively. Finally, the autogenous shrinkage behavior was simulated with several models in the literature, and a model for high strength self-compacting lightweight concrete with and without fibers considering equivalent age was proposed.