Properties of Sustainable High Performance Lightweight Aggregate Concrete Reinforced with Fibers

Abstract

In this investigation, sustainable High Performance Lightweight Aggregate Concrete (HPLWAC) containing recycled crushed clay brick from construction and demolition waste as coarse lightweight aggregate (LWA) and reinforced with mono fiber, double and triple hybrid fibers in different types and aspect ratios were produced. High Performance crushed brick lightweight aggregate concrete mix with compressive strength of 41.2MPa, oven dry density of 1930 kg/m3 at 28 days were prepared. The Fibers used including, macro hooked steel fiber with aspect ratio 60 (type S1), macro crimped plastic fiber (P) with aspect ratio 63, micro steel fiber with aspect ratio 65 (type S), and micro polypropylene fiber (PP) with aspect ratio 667. Six HPLWAC mixes were prepared including, one plain concrete mix (without fiber), two mono fiber reinforced concrete mixes ( reinforced with either steel fiber type S or plastic fiber with 0.75% volume fraction), two double hybrid fiber reinforced concrete mixes (0.5% steel fiber type S +0.25% polypropylene fiber and 0.5% plastic fiber + 0.25% steel fiber type S), and one mix with triple hybrid fiber (0.25% steel fiber type S1+0.25% polypropylene fiber +0.25% steel fiber type S). Fresh (workability and fresh density) and hardened concrete properties (oven dry density, compressive strength, splitting tensile strength, flexural strength and absorption) were studied. In general mono and hybrid (double and triple) fiber reinforced HPLWAC specimens give significant increases in splitting tensile strength and flexural strength compared with plain HPLWAC specimens. The percentages increase in splitting tensile strength for specimens with mono steel fiber are 55.8%, 65.9%, 82% and 91.9%, while for specimens with mono plastic fiber the percentages increase are 34%, 45.5%, 61.5% and 71.2% at 7, 28, 60, 90 days age respectively relative to the plain concrete. The maximum splitting tensile and flexure strengths were recorded for triple hybrid fiber reinforced HPLWAC specimens. The percentages increase in splitting tensile strength for triple hybrid fiber reinforced specimens are 57.2%, 68.6%, 87.5% and 101.8%, while the percentages increase in flexure strength are 84%, 95.6%, 6665% and 7.67% at 7, 28, 60 and 90 days age respectively relative to the plain concrete specimens.