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.

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.

Effects of Recycled Aggregate Replacement Rate on Compression Mechanical Behavior of Concrete Based on Base Force Element Method

2021 ◽  
Vol 894 ◽  
pp. 121-126
Author(s):  
Li Ping Ying ◽  
Yi Jiang Peng
Keyword(s):  
Failure Process ◽  
Strain Curve ◽  
Simple Algorithm ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Test Results ◽  
Force Element ◽  
Element Method

A meso-analysis method which is derived from the base force element method (BFEM) was proposed for recycled aggregate concrete (RAC). A simple algorithm was used to generate the convex recycled concrete aggregate (RCA) model. Uniaxial compression numerical simulations were carried out on the numerical specimens with different replacement rates of RCA. The model predictions were in a good agreement with the test results. The proposed method is very promising. It can totally predict the full stress-strain curve of RAC, as well as the failure process and failure mode, including strain softening and strain localization.

Mesoscopic numerical analysis of dynamic tensile fracture of recycled concrete

2020 ◽  
Vol 37 (6) ◽  
pp. 1899-1922 ◽  
Author(s):  
Liping Ying ◽  
Yijiang Peng ◽  
Mahmoud M.A. Kamel
Keyword(s):  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Failure Pattern ◽  
Recycled Aggregate ◽  
Tensile Fracture ◽  
Aggregate Model ◽  
Element Mesh ◽  
Content Type ◽  
Random Aggregate ◽  
Force Element

Purpose Based on the random aggregate model of recycled aggregate concrete (RAC), this paper aims to focus on the effect of loading rate on the failure pattern and the macroscopic mechanical properties. Design/methodology/approach RAC is regarded as a five-phase inhomogeneous composite material at the mesoscopic level. The number and position of the aggregates are modeled by the Walraven formula and Monte–Carlo stochastic method, respectively. The RAC specimen is divided by the finite-element mesh to establish the dynamic base force element model. In this model, the element mechanical parameters of each material phase satisfy Weibull distribution. To simulate and analyze the dynamic mechanical behavior of RAC under axial tension, flexural tension and shear tension, the dynamic tensile modes of the double-notched specimens, the simply supported beam and the L specimens are modeled, respectively. In addition, the different concrete samples are numerically investigated under different loading rates. Findings The failure strength and failure pattern of RAC have strong rate-dependent characteristics because of the inhomogeneity and the inertial effect of the material. Originality/value The dynamic base force element method has been successfully applied to the study of recycled concrete.

scholarly journals Discrete Element Simulation Analysis of Biaxial Mechanical Properties of Concrete with Large-Size Recycled Aggregate

2021 ◽  
Vol 13 (13) ◽  
pp. 7498
Author(s):  
Tan Li ◽  
Jianzhuang Xiao
Keyword(s):  
Mechanical Properties ◽  
Stress State ◽  
Strain Curve ◽  
Confining Pressure ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Model ◽  
Large Size

Concrete made with large-size recycled aggregates is a new kind of recycled concrete, where the size of the recycled aggregate used is 25–80 mm, which is generally three times that of conventional aggregate. Thus, its composition and mechanical properties are different from that of conventional recycled concrete and can be applied in large-volume structures. In this study, recycled aggregate generated in two stages with randomly distributed gravels and mortar was used to replace the conventional recycled aggregate model, to observe the internal stress state and cracking of the large-size recycled aggregate. This paper also investigated the mechanical properties, such as the compressive strength, crack morphology, and stress–strain curve, of concrete with large-size recycled aggregates under different confining pressures and recycled aggregate incorporation ratios. Through this research, it was found that when compared with conventional concrete, under the confining pressure, the strength of large-size recycled aggregate concrete did not decrease significantly at the same stress state, moreover, the stiffness was increased. Confining pressure has a significant influence on the strength of large-size recycled aggregate cocrete.

scholarly journals Micromechanical Numerical Modelling on Compressive Failure of Recycled Concrete using Discrete Element Method (DEM)

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4329
Author(s):  
Xin Tan ◽  
Zhengbo Hu ◽  
Wengui Li ◽  
Suhua Zhou ◽  
Tenglong Li
Keyword(s):  
Discrete Element Method ◽  
Numerical Simulations ◽  
Discrete Element ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Image Correlation ◽  
Recycled Aggregate ◽  
Nanoindentation Test ◽  
Aggregate Concrete ◽  
Element Method

This paper investigates the failure processes of recycled aggregate concrete by a model test and numerical simulations. A micromechanical numerical modeling approach to simulate the progressive cracking behavior of the modeled recycled aggregate concrete, considering its actual meso-structures, is established based on the discrete element method (DEM). The determination procedure of contact microparameters is analyzed, and a series of microscopic contact parameters for different components of modeled recycled aggregate concrete (MRAC) is calibrated using nanoindentation test results. The complete stress–strain curves, cracking process, and failure pattern of the numerical model are verified by the experimental results, proving their accuracy and validation. The initiation, growth, interaction, coalescence of microcracks, and subsequent macroscopic failure of the MRAC specimen are captured through DEM numerical simulations and compared with digital image correlation (DIC) results. The typical cracking modes controlled by meso-structures of MRAC are concluded according to numerical observations. A parameter study indicates the dominant influence of the macroscopic mechanical behaviors from the shear strength of the interfacial transition zones (ITZs).

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.

Seismic Test on a Damaged Structure with Recycled Concrete Blocks

2012 ◽  
Vol 517 ◽  
pp. 528-535
Author(s):  
Jian Zhuang Xiao ◽  
Chang Qing Wang
Keyword(s):  
Damage Model ◽  
Masonry Structure ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Shaking Table ◽  
Recycled Aggregate ◽  
Acceleration Response ◽  
Aggregate Concrete ◽  
The Wenchuan Earthquake ◽  
Concrete Blocks

A man-made damaged model of a one-storey block masonry structure with recycled aggregate concrete (RAC) was tested on a shaking table The Wenchuan earthquake wave, El Centro earthquake wave and Shanghai artificial wave were selected and input to the model with different earthquake levels in the shaking table tests. The recycled aggregate concrete (RAC) block masonry structure was damaged firstly by cutting the tie columns and its seismic behavior was experimentally investigated. The dynamic characteristics, the displacement response, the acceleration response were record. In comparison with the intact model, there is an obvious decrease in the seismic performance of the RAC block masonry man-made damage model.

scholarly journals Experimental Study on the Mechanical Properties and Compression Size Effect of Recycled Aggregate Concrete

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2323
Author(s):  
Yubing Du ◽  
Zhiqing Zhao ◽  
Qiang Xiao ◽  
Feiting Shi ◽  
Jianming Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Size Effect ◽  
Compressive Stress ◽  
Failure Modes ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Substitution Ratio ◽  
The Impact

To explore the basic mechanical properties and size effects of recycled aggregate concrete (RAC) with different substitution ratios of coarse recycled concrete aggregates (CRCAs) to replace natural coarse aggregates (NCA), the failure modes and mechanical parameters of RAC under different loading conditions including compression, splitting tensile resistance and direct shear were compared and analyzed. The conclusions drawn are as follows: the failure mechanisms of concrete with different substitution ratios of CRCAs are similar; with the increase in substitution ratio, the peak compressive stress and peak tensile stress of RAC decrease gradually, the splitting limit displacement decreases, and the splitting tensile modulus slightly increases; with the increase in the concrete cube’s side length, the peak compressive stress of RAC declines gradually, but the integrity after compression is gradually improved; and the increase in the substitution ratio of the recycled aggregate reduces the impact of the size effect on the peak compressive stress of RAC. Furthermore, an influence equation of the coupling effect of the substitution ratio and size effect on the peak compressive stress of RAC was quantitatively established. The research results are of great significance for the engineering application of RAC and the strength selection of RAC structure design.

Study on the Basic Mechanical Properties of Recycled Concrete Hollow Block Masonry

2013 ◽  
Vol 438-439 ◽  
pp. 749-755 ◽  
Author(s):  
Tong Hao ◽  
Dong Li
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Shear Behavior ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Test Results ◽  
Aggregate Concrete ◽  
Mortar Strength ◽  
Hollow Block

By the experimental studying on the basic mechanical properties of recycled concrete hollow block masonry, the compressive and shear behavior of recycled aggregate concrete hollow block masonry under different mortar strength were analyzed. Research indicated that the compressive and shear behavior of recycled aggregate concrete hollow block masonry was similar to that of ordinary concrete hollow block masonry. The normal formula was recommended to calculate the compressive strength of the masonry. The shear strength of the masonry was affected by the mortar strength. The shear strength calculation formula of recycled concrete hollow block masonry was proposed according to the formula of masonry design code. The calculating results were in good agreement with the test results.

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