Some Properties of Hybrid Fibers High Strength Lightweight Aggregate Concrete

Abstract

This investigation aims to study some properties of high strength lightweight aggregate concrete (HSLWAC) reinforcedwith mono and hybrid fibers in different dimensions and types. High strengthporcelinite lightweight aggregate concretemix with compressive strength 41 MPa at 28 day age was prepared. The fibers used included macro hooked steel fiber with aspect ratio 100 (type S1), macro hooked steel fiber with aspect ratio 60 (type S2), micro polypropylene fiber (pp)and micro carbon fiber (CF). Eight HSLWAC mixes were prepared including, one plain concrete mix (without fibers), three mono (single) fiber reinforced concrete mixes (with 0.5% volume fraction of steel fiber type S1, 1% volume fraction of steel fiber type S1and 0.25% volume fraction of CF) and four double hybrid fiber reinforced concretes mixes [0.5% steel fiber type S1 +0.5% steel fiber S2 mix (HSF1), 0.75% steel fiber S1+ 0.25% steel fiber type S2mix ( HSF2), 0.75% steel fiber type S1+ 0.25% pp mix (HSPPF) and 0.75% steel fiber type S1+ 0.25% CF mix (HSCF)]. Fresh properties (workability and fresh density) and hardened properties (oven dry density, compressive strength, splitting tensile strength, flexural strength and thermal conductivity) of HSLWAC were studied. Generally mono and hybrid fiber reinforced HSLWAC specimens show significant increase in splitting tensile strength and flexural strength in comparison with plain HSLWAC specimen. All hybrid fiber HSLWAC specimens show significant increase in splitting tensile strength and flexural strength compared to concrete specimens reinforced with 1% volume fraction of mono steel fiber type S1. The percentage of increase in splitting tensile strength for hybrid fiber reinforced specimens prepared from HSLWAC mixes HSF1, HSF2, HSPPF and HSCF is 316.6%, 361.1%, 377.7% and 433.3%, while the percentage of increase in flexural strength is 29.43%, 59.89%, 26.56% and 64.58% respectively relative to the plain specimens.