Fracture properties of hybrid fibre-reinforced roller-compacted concrete in mode I with consideration of possible kinked crack

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Pure mode I and mode II fracture toughness of asphalt mixture was investigated both experimentally and theoretically using vertical edge crack semicircular bend (SCB) specimen with symmetric and asymmetric bottom loading spans. The thickness of SCB specimen was considered in the range from 30 to 70 mm, and the fracture toughness tests were performed at three subzero temperatures (−5 C, −15 C and −25 C). The results showed that K Ic and K IIc are increased by reducing the test temperature. The thickness had no sound effect on the fracture toughness, but the thickness of 50 mm was more suitable for fracture study on this material. The fracture load of mode II specimen was significantly greater than the mode I fracture load at the same testing condition. The fracture toughness ratio (K IIc /K Ic) that varies in the range between 1 and 1.4 was predicted theoretically using three well-known stress/strainbased fracture criteria. K E Y W O R D S asphalt mixture, fracture toughness ratio prediction, K Ic and K IIc value, low temperature, symmetric and asymmetric SCB specimens, thickness effect

Section: Introductionmentioning

confidence: 99%

K_IcandK_IIcmeasurement for hot mix asphalt mixtures at low temperature: Experimental and theoretical study using the semicircular bend specimen with different thicknesses

Yuan

Tian

Liu

et al. 2020

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“…These specimens include the single edge notched bend beam (SENB) subjected to three or four point bend loading, 4,8,20,26,27,35,42 the modified indirect tension (IDT) specimen, 21,25,36,38 the edge notched disc bend (ENDB) specimen subjected to threepoint bend loading, 7 the edge notched diametrically compressed (ENDC) disc specimen, 7 the disc shape compact tension (DCT) specimen, 14,22-24 the centre cracked circular disc specimen subjected to diametral compression, 43 and the semi-circular bend (SCB) specimen subjected to three-point bend loading. These specimens include the single edge notched bend beam (SENB) subjected to three or four point bend loading, 4,8,20,26,27,35,42 the modified indirect tension (IDT) specimen, 21,25,36,38 the edge notched disc bend (ENDB) specimen subjected to threepoint bend loading, 7 the edge notched diametrically compressed (ENDC) disc specimen, 7 the disc shape compact tension (DCT) specimen, 14,22-24 the centre cracked circular disc specimen subjected to diametral compression, 43 and the semi-circular bend (SCB) specimen subjected to three-point bend loading.…”

Section: Fracture Specimenmentioning

confidence: 99%

“…There are different test specimens for fracture toughness study of asphalt mixtures. These specimens include the single edge notched bend beam (SENB) subjected to three or four point bend loading, 4,8,20,26,27,35,42 the modified indirect tension (IDT) specimen, 21,25,36,38 the edge notched disc bend (ENDB) specimen subjected to threepoint bend loading, 7 the edge notched diametrically compressed (ENDC) disc specimen, 7 the disc shape compact tension (DCT) specimen, 14,22-24 the centre cracked circular disc specimen subjected to diametral compression, 43 and the semi-circular bend (SCB) specimen subjected to three-point bend loading. 6,[8][9][10][11]31,34 The simple geometry and loading condition of the SCB specimen makes it one of the most popular test specimens for determining the fracture parameters of asphalt mixtures.…”

Section: Fracture Specimenmentioning

confidence: 99%

Heterogeneity effects on mixed‐mode I/II stress intensity factors and fracture path of laboratory asphalt mixtures in the shape of SCB specimen

Aliha

Ziari

Mojaradi

et al. 2019

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Edge cracked semi-circular shape specimen subjected to three point bend loading is a favourite test specimen for determining fracture toughness of asphalt mixtures. However, in the vast majority of previous experimental works, the homogeneous medium assumption has been considered for determining the stress intensity factor and geometry factors of asphalt mixtures tested with this test configuration. As a more realistic model and in order to consider the effects of heterogeneity on corresponding values of stress intensity factors, the asphalt mixture was modelled as a two-phase aggregate/mastic heterogeneous mixture and its fracture behaviour was investigated using numerical models of asymmetric semi-circular bend (ASCB) specimens. The generation and packing algorithm was employed to randomly distribute the aggregates with different shapes and sizes inside the mastic part. The effect of the mechanical properties of asphalt mixture (elastic modulus and the Poisson's ratios of aggregates and mastic), coarse aggregates distribution and crack length were studied on modes I and II geometry factors by means of extensive twodimensional finite element analyses. Moreover, the effect of the elastic modulus of asphalt mixture components was evaluated on the fracture path using the maximum tangential stress criterion. It was shown that crack tip location, elastic modulus of aggregates and mastic are the most important affecting parameters on the magnitude of modes I and II geometry factors. It was also shown that the geometry factors are not sensitive to the Poisson's ratios of aggregates and mastic. In addition, fracture cracking path is affected by the elastic modulus of the asphalt mixture components such that, depending on the difference between the stiffness of stiffer coarse aggregates and softer NOMENCLATURE: K I , K II , stress intensity factors of modes I and II; K Ic , K IIc , critical stress intensity factors of modes I and II; Y I , Y II , geometry factors of modes I and II; P, applied load; P c , critical fracture load; R, radius of the SCB specimen; t, thickness of the SCB specimen; E, Young's modulus; E agg , Young's modulus of aggregates; E mastic , Young's modulus of mastic; E interface , Young's modulus of interface; D, distribution of aggregates in the SCB sample; Xi, Yi, Cartesian coordinate of new generated aggregate; R i , radius of new generated aggregate; X j , Y j , Cartesian coordinate of generated aggregate in the previous steps; R j , radius of generated aggregate in the previous steps; a, crack length; S 1 , S 2 , bottom support distances; S 1 /R, S 2 /R, bottom support distances over the radius ratios; A ij , area of aggregate j in group i; A i max , maximum summation area of aggregates in group i; A i min , minimum summation area of aggregates in group i; SCB, semicircular bending sample; MTS, maximum tangential stress; HMA, hot mix asphalt; SIF, stress intensity factor

“…Generally, fibers play a main role in the postcracking zone; and the inclusion of fibers could increase the toughness and energy absorption capacity of concrete. The overall performance of concrete is enhanced with the addition of different fibers because the single fiber could only be effective in a single aspect based on fiber size and type 9,10 . Hybrid fiber concrete is produced using different characteristics (sizes, types, etc.)…”

Section: Introductionmentioning

confidence: 99%

Efficiency of basalt fiber length and content on mechanical and microstructural properties of hybrid fiber concrete

Khan

Cao

Xie

et al. 2021

Recently, multiscale hybrid fiber‐reinforced concrete is used instead of single fiber‐reinforced concrete to achieve better performance with hybrid fiber at their respective scale size. In this study, the fracture properties of multiscale hybrid fiber‐reinforced concrete are considered. This work aims to evaluate the effect of different basalt fiber (BF) lengths and contents on fracture parameters of fly ash–CaCO3 whisker–steel fiber‐reinforced concrete (FCSF). The measured fracture parameters are initial fracture toughness (KICini), unstable fracture toughness ( KICuns), fracture energy (GF) by various methods, and gain ratio (GR) of fracture parameters. Furthermore, the cracking mechanism and microstructural study are discussed. The different considerable amount of enhancement was indicated by FCSF‐BF for fracture characteristics as compared to that of plain concrete (PC).