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Automatic mesoscopic fracture modelling of concrete based on enriched SBFEM space and quad-tree mesh

- Jiang, Shouyan, Sun, Liguo, Ooi, Ean Tat, Ghaemian, Mohsen, Du, Chengbin

  • Authors: Jiang, Shouyan , Sun, Liguo , Ooi, Ean Tat , Ghaemian, Mohsen , Du, Chengbin
  • Date: 2022
  • Type: Text , Journal article
  • Relation: Construction and Building Materials Vol. 350, no. (2022), p.
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  • Description: A novel approach for mesoscale modelling of concrete composites is proposed by combining enriched scaled boundary finite element methods with quad-tree mesh. The concrete meso-structures are comprised of randomly distributed aggregates, mortar matrix, and interface transition zone. An improved random aggregate generation technique is developed to construct digital images of mesoscale concrete models. Based on the quadtree decomposition algorithm, meshes can be generated automatically from the digital images of concrete mesostructure. The whole mesh generation process is highly efficient without any artificial interference and eliminates the issue of hanging nodes faced by standard finite elements. Additionally, local remeshing is unnecessary as crack propagates. Three numerical examples are modelled to demonstrate the performance of the proposed approach, and the effects of aggregate area fraction on the mechanical properties of concrete composites are also discussed. © 2022 Elsevier Ltd

Recycling timber waste into geopolymer cement bonded wood composites

- Gigar, Firesenay, Khennane, Amar, Liow, Jong-Leng, Tekle, Biruk, Katoozi, Elmira

  • Authors: Gigar, Firesenay , Khennane, Amar , Liow, Jong-Leng , Tekle, Biruk , Katoozi, Elmira
  • Date: 2023
  • Type: Text , Journal article
  • Relation: Construction and Building Materials Vol. 400, no. (2023), p.
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  • Description: Addressing critical societal challenges, such as climate change, resource depletion, and environmental protection, requires sustainable management of resources. This study reports on the results of an experimental program using waste wood, including chromium copper arsenic (CCA) treated wood, to produce ambiently cured geopolymer cement bonded wood composites (WGC), and the results are very encouraging. The composite exhibited a reasonable compressive strength, which ranged between 7 and 27 MPa inversely corresponding to the amount of wood per binder ratio ranging between 0.1 and 0.4, conferring it the possibility of being used as a building material. The compressive strength of the composite with 40% wood chips showed the lowest compressive strength with values of 9.79, 7.29, and 7.92 MPa for decontaminated, CCA-treated, and non-CCA-treated wood chips, respectively. The results indicated that for all the wood per binder ratios, the use of decontaminated wood chips significantly improves the compressive, flexural, and specific strength of the composites, as well as their ductility, compared to non-decontaminated CCA-treated and non-CCA-treated wood chips. This paves the way for using wood waste in sustainability oriented product development and manufacturing. © 2023 The Author(s)

A comparison between porosities measured from specimens with regular and irregular shapes and their accuracy in predicting the strength characteristics of carbonate building stones

- Jamshidi, Amin, Ajalloeian, Rassoul, Hashemi, Morteza, Aligholi, Saeed, Emami Mybodi, Mohammad

  • Authors: Jamshidi, Amin , Ajalloeian, Rassoul , Hashemi, Morteza , Aligholi, Saeed , Emami Mybodi, Mohammad
  • Date: 2024
  • Type: Text , Journal article
  • Relation: Construction and Building Materials Vol. 452, no. (2024), p.
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  • Description: Porosity is among the basic physical parameters widely used in evaluating the strength characteristics of building stones. Based on the geometric shape of the stone specimen, there are two procedures for determining the porosity: 1) measurements on specimens with regular shapes and 2) measurements on specimens with irregular shapes. The present study correlates the strength characteristics of stones and porosities measured from specimens with regular and irregular shapes. To this end, samples of carbonate stones were collected from different locations in Iran. The porosity of the samples was measured for specimens with regular (nr) and irregular (nir) shapes. Next, the strength characteristics of the samples, including uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), and point load index (PLI), were determined. Results revealed that for all samples, nr has lower values than nir. Based on the scanning electron microscope (SEM) micrographs, this difference is due to the filling of some pore spaces of the specimens with regular shapes during their preparation by the coring machine. UCS, BTS, and PLI(50) were correlated with nr and nir using simple regression analyses. The accuracy of the correlation equations was compared based on their determination coefficient (R2) and diagonal line (1:1) measures. The findings indicated that nir provides higher accuracy than nr in evaluating the UCS, BTS, and PLI(50) of the samples. The effect of dry density (

Experimental and finite element study of bond behavior between seawater sea-sand alkali activated concrete and FRP bars

- Cui, Yifei, Qu, Shihao, Tekle, Biruk, Ai, Weixia, Liu, Menghua, Xu, Nuo, Zhang, Yicong, Zhang, Peng, Leonovich, Sergei, Sun, Jianwei, Miao, Jijun

  • Authors: Cui, Yifei , Qu, Shihao , Tekle, Biruk , Ai, Weixia , Liu, Menghua , Xu, Nuo , Zhang, Yicong , Zhang, Peng , Leonovich, Sergei , Sun, Jianwei , Miao, Jijun
  • Date: 2024
  • Type: Text , Journal article
  • Relation: Construction and Building Materials Vol. 424, no. (2024), p.
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  • Description: The bond performance of fiber reinforced plastic (FRP) bars in seawater sea sand alkali activated concrete (SSASC) was investigated using pull-out test specimens. The effect of different concrete strengths, anchorage lengths, FRP bar types, and diameters on the bond performance were investiaged. Special emphasis was given to the applicability of the existing bond-slip constitutive models to FRP reinforced SSASC, which was investigated by calibrating well-known models to the experimental results. The correlation between the experimental curve and different bond-slip constitutive models is analyzed by calculating the R2 value. To verify the applicability of finite element analysis to SSASC and FRP bars system, numerical simulation was performed in ABAQUS finite element simulation software by setting the same conditions as the experimental variables. The results indicate that the Fan Xiaochun's model, which is the modifications of the MBPE model, has a high degree of correlation and is more suitable for SSASC and FRP bars system. The simulation results using ABAQUS finite element software are in good agreement with the experimental results. © 2024 Elsevier Ltd
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