scholarly journals Numerical Studies on Damage Behavior of Recycled Aggregate Concrete Based on a 3D Model

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 355
Author(s):  
Yao Wang ◽  
Huawei Zhao ◽  
Minyao Xu ◽  
Chunyang Wu ◽  
Jiajia Fu ◽  
...  
Keyword(s):  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Energy Principle ◽  
Aggregate Concrete ◽  
Numerical Studies ◽  
Weak Points ◽  
Force Element ◽  
Gaussian Integral ◽  
Major Factors ◽  
Weak Zones

This paper develops a 3D base force element method (BFEM) based on the potential energy principle. According to the BFEM, the stiffness matrix and node displacement of any eight-node hexahedral element are derived as a uniform expression. Moreover, this expression is explicitly expressed without a Gaussian integral. A 3D random numerical model of recycled aggregate concrete (RAC) is established. The randomness of aggregate was obtained by using the Monte Carlo random method. The effects of the recycled aggregate substitution and adhered mortar percentage on the elastic modulus and compressive strength are explored under uniaxial compression loading. In addition, the failure pattern is also studied. The obtained data show that the 3D BFEM is an efficient method to explore the failure mechanism of heterogeneous materials. The 3D random RAC model is feasible for characterizing the mesostructure of RAC. Both the substitution of recycled aggregate and the percentage of adhering mortar have a non-negligible influence on the mechanical properties of RAC. As the weak points in the specimen, the old interfacial transition zone (ITZ) and adhered mortar are the major factors that lead to the weakened properties of RAC. The first crack always appears in these weak zones, and then, due to the increase and transfer of stress, approximately two-to-three continuous cracks are formed in the 45°direction of the specimen.

scholarly journals Application of Base Force Element Method to Mesomechanics Analysis for Recycled Aggregate Concrete

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Yijiang Peng ◽  
Yinghua Liu ◽  
Jiwei Pu ◽  
Lijuan Zhang
Keyword(s):  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Triangular Element ◽  
Aggregate Model ◽  
Energy Principle ◽  
Aggregate Concrete ◽  
Tension Tests ◽  
Random Aggregate ◽  
Force Element ◽  
Element Method

The base force element method (BFEM) on potential energy principle is used to analyze recycled aggregate concrete (RAC) on mesolevel. The model of BFEM with triangular element is derived. The recycled aggregate concrete is taken as five-phase composites consisting of natural coarse aggregate, new mortar, new interfacial transition zone (ITZ), old mortar, and old ITZ on meso-level. The random aggregate model is used to simulate the mesostructure of recycled aggregate concrete. The mechanics properties of uniaxial compression and tension tests for RAC are simulated using the BFEM, respectively. The simulation results agree with the test results. This research method is a new way for investigating fracture mechanism and numerical simulation of mechanics properties for recycled aggregate concrete.

scholarly journals Modeling the Failure Pattern of Prenotched Recycled Aggregate Concrete Using FEM on Complementary Energy Principle

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Yao Wang ◽  
Gang Zong ◽  
Juan Liu ◽  
Chunyang Wu ◽  
Minyao Xu ◽  
...  
Keyword(s):  
Crack Path ◽  
Numerical Models ◽  
Recycled Aggregate Concrete ◽  
Failure Pattern ◽  
Recycled Aggregate ◽  
Complementary Energy ◽  
Energy Principle ◽  
Compliance Matrix ◽  
Aggregate Concrete ◽  
Complementary Energy Principle

The reuse of recycled aggregate concrete (RAC) is being researched all over the world and lots of works are focused on the notched specimen to study the crack path of RAC. A mathematical algorithm of RAC meshing was presented to explore the failure pattern in RAC. According to this algorithm, the interfacial transition zone can be defined to be an actual thickness at the micron level. Further, a new finite element method (FEM) on the complementary energy principle was introduced to simulate the mechanical behavior of RAC’s mesostructure. The compliance matrix of the element with any shape can be calculated and expressed to be a uniform and explicit expression. Several numerical models of RAC were established, in which the effecting factors of the prenotch size, thickness of ITZ, and the distance from the prenotch to the aggregate were taken into account. Hereafter, these RAC models were subjected to uniaxial tension. The effect of the aforementioned factors on the crack path was simulated. The simulated data manifest that both the mesh mode of RAC and the FEM on complementary energy principle are effective approaches to explore the failure pattern of RAC. The size of the prenotch, thickness of ITZ, and distance from the prenotch to the recycled aggregate have a powerful influence on the path and distribution of the isolated crack, width and length of the crack path, and the shape and path of continuous cracks, respectively.

scholarly journals Numerical Simulation of Recycled Concrete Using Convex Aggregate Model and Base Force Element Method

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Yijiang Peng ◽  
Hao Chu ◽  
Jiwei Pu
Keyword(s):  
Damage Model ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Model ◽  
Energy Principle ◽  
Force Element ◽  
Damage Processes ◽  
Random Convex ◽  
Element Method

By using the Base Force Element Method (BFEM) on potential energy principle, a new numerical concrete model, random convex aggregate model, is presented in this paper to simulate the experiment under uniaxial compression for recycled aggregate concrete (RAC) which can also be referred to as recycled concrete. This model is considered as a heterogeneous composite which is composed of five mediums, including natural coarse aggregate, old mortar, new mortar, new interfacial transition zone (ITZ), and old ITZ. In order to simulate the damage processes of RAC, a curve damage model was adopted as the damage constitutive model and the strength theory of maximum tensile strain was used as the failure criterion in the BFEM on mesomechanics. The numerical results obtained in this paper which contained the uniaxial compressive strengths, size effects on strength, and damage processes of RAC are in agreement with experimental observations. The research works show that the random convex aggregate model and the BFEM with the curve damage model can be used for simulating the relationship between microstructure and mechanical properties of RAC.

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