Fracture studies on synthetic fiber reinforced cellular concrete using acoustic emission technique

Abstract

Cellular lightweight concrete (CLC) is increasingly used for low strength non-structural and structural applications. The effects of synthetic fiber reinforcement on the fracture behavior of CLC is investigated. In particular, acoustic emission (AE) technique is employed to study the influence of macro (structural), micro polyolefin synthetic fibers and their combinations on the fracture behavior of CLC beams. Notched fiber reinforced CLC beams were tested to study the crack initiation and propagation characteristics using AE sensors. Different AE parameters are correlated with the crack growth and damage accumulation. An attempt has been made to correlate the crack mouth opening displacement (CMOD) with the number of AE hits. The variation of cumulative acoustic energy release of the cracks is studied with respect to applied load and CMOD. Three dimensional source location of cracks is carried out based on the AE events picked by the sensors bonded to the CLC specimens. The analysis of AE results indicates that the crack source location identification from AE is consistent with the actual crack development. Analysis of AE signals reveal that the CLC matrix cracking produces signals with less number of hits that lie in the notched plane in bending. Moreover, the signals from the post peak regime correspond to more number of hits which tend to be scattered around the plane of notch due to the fiber pull out.

Compressive behaviors of ultra-low-weight foamed cement-based composite reinforced by polypropylene short fibers

“…With advantageous properties like low specific density, energy absorbing, low thermal conductivity, and high acoustic insulation, lightweight foamed cement-based composites are increasingly used in various low strength structural and nonstructural applications (Rasheed et al., 2018). The foamed cement-based material is such a lightweight porous material which is prepared by chemical or physical foaming procedure (Krämer et al., 2015).…”

“…As extensively studied, the cementitious composites were quasi-brittle materials with brittle matrix and low strain capacity (Zhang et al., 2013). Short and randomly distributed fibers normally are used to improve the brittleness and poor resistance of crack initiation and propagation of composites (Park et al., 2017; Rasheed et al., 2018). The incorporation of fibers as the reinforcement in foamed cement-based composites is also proved an effective method to improve the mechanical strength and ductile properties (Rasheed et al., 2018).…”

“…Short and randomly distributed fibers normally are used to improve the brittleness and poor resistance of crack initiation and propagation of composites (Park et al., 2017; Rasheed et al., 2018). The incorporation of fibers as the reinforcement in foamed cement-based composites is also proved an effective method to improve the mechanical strength and ductile properties (Rasheed et al., 2018). One of the most important advantages of short fiber reinforcement in foamed cement-based composites has been demonstrated to enhance energy absorption and strain capacity during the structural cracking (Rasheed et al., 2018; Yan et al., 2019).…”

“…The incorporation of fibers as the reinforcement in foamed cement-based composites is also proved an effective method to improve the mechanical strength and ductile properties (Rasheed et al., 2018). One of the most important advantages of short fiber reinforcement in foamed cement-based composites has been demonstrated to enhance energy absorption and strain capacity during the structural cracking (Rasheed et al., 2018; Yan et al., 2019). The short synthetic fibers are noncorrosive and malleable, and they are widely used to strengthen the cement mortar or concrete (not lightweight) to prevent the crack and flaw propagating and coalescing (Yang and Deng, 2018; Yang et al., 2019).…”

Relation between the shear stress distribution and the resulting acoustic emission variation in concrete beams

“…Carpinteri et al evaluated the damage localisation of strengthened walls using AE technology and predicted the time to failure in fatigue tests. Rasheed et al employed an AE technique to study the influence of different polyolefin synthetic fibres and their combinations on the fracture behaviour of cellular lightweight concrete beams, and results indicated that the crack sources located by the technique were consistent with the actual crack development. Wang et al applied an AE analysis method to monitor the damage evolution of ultra‐high performance concrete (UHPC) specimens subjected to direct tension and concluded that the method provided great insight into the multiple cracking behaviour of UHPC during the strain‐hardening stage.…”