Toughness behaviour of high‐performance lightweight foamed concrete reinforced with hybrid fibres

Abstract

Lightweight foamed concrete (LWFC) is.Foamed concrete is produced either by a prefoaming or a mixed foaming method. The prefoaming method involves the separate production of base mix cement slurry (cement paste or mortar) and a stably preformed (foaming agent with water) and then the thorough blending of this foam into a base mix. In mixed foaming, the surface-active agent is mixed with the base mix ingredients and foam is produced during the mixing process, resulting in a cellular structure in the concrete [3]- [5]. Structural lightweight concrete (SLWC) is similar to normal-weight concrete except that it has a lower density [6]. SLWC is defined as a concrete having a compressive strength of up to 17 MPa with a bulk density less than 1950 kg/m 3 ; structural lightweight concrete can be 25 % lighter than normal-weight concrete but have a compressive strength of up to 60 MPa [7]. The term high-performance concrete (HPC) is used for concrete mixes that possess the following three properties: highworkability, highstrength and high durability [8].Plain concrete is a brittle material, which results in poor fracture toughness, poor resistance to crack propagation and low impact strength. This inherent brittleness has limited its application in fields requiring high impact, vibration and fracture strengths. Fibres are used to modify the tensile and flexural strengths, toughness, impact resistance and fracture energy, and to arrest crack formation and propagation and thus improve strength and ductility [9]-[12]. Glass fibres improve the strength of the material by increasing the force required for deformation and enhance the toughness by increasing the energy required for crack propagation [13]. Ghorpade [14] investigated the effect of glass fibre on high-performance concrete with silica fume as an admixture. The maximum percentage increase in compressive strength was observed at 1 % fibre and 10 % silica fume content. The flexural strength increases with up to 1 % of fibre volume, thus, the strength decreases. Polypropylene fibres are the most popular of the synthetics. They are chemically inert, hydrophobic and lightweight. Polypropylene fibres reduce plastic shrinkage cracking and subsidence cracking over steel reinforcement [6]. Banthia and Gupta [15] investigated the influ-

Fibre-Reinforced Foamed Concretes: A Review

“…FC’s compressive strength commonly decreases gradually as the entrapped bubbles increased; however, its strength may be enhanced by adding fibres into the concrete matrix. Massive research [ 29 , 31 , 169 ] has shown that various fibres can enhance FC properties [ 6 , 7 , 8 ]. Also, it has been proven that these fibres can enhance its hardened properties (including fresh, physical properties, toughness and elasticity) with experimental evidence [ 8 , 23 , 38 , 170 , 171 , 172 ] ( Table 7 ).…”

“…High-strength foamed concrete is obtained by introducing polypropylene (PP) fibre into the raw mix [ 2 , 18 ]. Many of the currently used fibres have been investigated, including PP [ 29 , 30 ], blend of polypropylene with glass [ 31 ], cellulose [ 32 ], kenaf [ 27 , 33 ], steel [ 26 ], palm oil, coconut [ 34 ], and other fibres [ 2 , 18 , 35 ]. In the previously listed studies, these fibres were introduced in an amount of 0.2–1.5% volume of the concrete mixture; however, in this article, the fibre content ranges upper limit has been extended to 5%.…”

Effect of ceramic waste powder as partial fine aggregate replacement on properties of fiber‐reinforced aerated concrete

“…Inasmuch the concrete deemed a brittle material and poor tensile strength, the fibers were used in concrete to enhance the tensile strength properties of concrete. Fibers enhance and modify the tensile strength, flexural toughness, impact resistance, fracture energy, arrest cracks formation and propagation, and improve the strength and ductility . Aerated concrete (AC) is one of the LWC types formed by creating gas bubbles within a conventional concrete that aluminum powder reacts with the calcium hydroxide created by cement hydration to generate hydrogen gas bubbles .…”

“…Fibers enhance and modify the tensile strength, flexural toughness, impact resistance, fracture energy, arrest cracks formation and propagation, and improve the strength and ductility. 2,4 Aerated concrete (AC) is one of the LWC types formed by creating gas bubbles within a conventional concrete that aluminum powder reacts with the calcium hydroxide created by cement hydration to generate hydrogen gas bubbles. 5 Supplementary cementitious materials (SCM) used as a replacement by weight of cement or fine aggregate to obtain sustainable concrete by reducing the cement consuming.…”

Behavior of foamed concrete reinforced with hybrid fibers and exposed to elevated temperatures

“…The percentage of increase in splitting tensile strength for hybrid fiber (0.75 SF + 0.25 CF) up to 433%, while the percentage of increase in flexural strength is about 65% compared with the plain specimens. Dawood and Hamad [7], have also studied the LWFC reinforced with hybrid fibers using different percentages of glass and polypropylene fibers. The authors have found that the use of "0.4% glass fiber + 0.6% polypropylene fiber" has shown the best performance of LWFC.…”