Abstract
In this investigation, sustainable High Performance Lightweight Aggregate Concrete (HPLWAC) containing artificial aggregate 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 artificial lightweight aggregate concrete mix with compressive strength of 47 MPa, oven dry density of 1828 kg/m3 at 28 days was prepared. The Fibers used included, macro hooked steel fiber with aspect ratio of 60 (type S1), macro crimped plastic fiber (P) with aspect ratio of 63, micro steel fiber with aspect ratio of 65 (type S), and micro polypropylene fiber (PP) with aspect ratio of 667. Four HPLWAC mixes were prepared including, one plain concrete mix (without fiber), one mono fiber reinforced concrete mixes (reinforced with plastic fiber with 0.75% volume fraction), one double hybrid fiber reinforced concrete mixes (0.5% plastic fiber + 0.25% steel fiber type S), and a 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, ultrasonic pulse velocity, splitting tensile strength, flexural strength, static modules of elasticity, thermal conductively, and water absorption) were studied. Generally, mono and hybrid (double and triple) fiber reinforced HPLWAC specimens give a significant increase in splitting tensile strength and flexural strength compared with plain HPLWAC specimens. The percentage increases in splitting tensile strength for specimens with mono plastic fiber are, 20.8%, 31.9%, 36.4% and 41%, while the percentage increases in flexure strength are 19.5%, 37%, 33.9% and 34.2% 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 percentage increases in splitting tensile strength for triple hybrid fiber reinforced specimens are 19.5%, 37%, 33.9% and 34.2%, while the percentage increases in flexure strength are 50.5%, 62.4. %, 66.8% and 62.2% at 7, 28, 60 and 90 days age respectively relative to the plain concrete specimens.
Highlights
High performance structural lightweight concrete (HPSLWC) is an advanced in concrete technology which has the properties of High Performance Concrete (HPC) and Lightweight Concrete (LWC) such as, high strength, low permeability, low density, and high thermal insulation properties which are appropriate for many applications
4.1 Selection of mix proportions for high performance LWAC Reference lightweight aggregate concrete mix was designed in accordance with ACI 211.2 [28] without any admixtures with compressive strength of 20 MPa at age 28 days
[3] The compressive strength of concrete specimens at different ages decreases with the addition of mono plastic fiber in the range from (6% -13%), while the inclusion of double and triple hybrid fiber slightly improves the compressive strength relative to the plain concrete specimens
Summary
High performance structural lightweight concrete (HPSLWC) is an advanced in concrete technology which has the properties of High Performance Concrete (HPC) and Lightweight Concrete (LWC) such as, high strength, low permeability, low density, and high thermal insulation properties which are appropriate for many applications. Splitting and flexural tensile strengths of single and hybrid fiber were increased in the range of 16% - 52% and 1% - 28% respectively compared to plain LWAC. Lightweight aggregate concrete containing mono and triple fiber showed higher splitting and flexural strengths when compared with double hybrid fibers. Compressive strength, modulus of elasticity, splitting tensile strength, modulus of rupture and the flexural load-displacement behavior of the lightweight aggregate concrete with hybrid fiber addition were studied. The splitting tensile strength and modulus of rupture for hybrid LWAC with 0.1% polypropylene + 1.5% steel fiber improved by about 222.28% and 187.47% respectively. Flexural performance is much better in hybrid fiber reinforced LWAC of 0.1% polypropylene +1.5% steel compared to the plain concrete mixes
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