Mesoscale modeling of recycled aggregate concrete under uniaxial compression and tension using discrete element method

2021 ◽  
Vol 268 ◽  
pp. 121116
Author(s):  
Yong Yu ◽  
Yu Zheng ◽  
Xin-Yu Zhao
Keyword(s):  
Discrete Element Method ◽  
Uniaxial Compression ◽  
Discrete Element ◽  
Recycled Aggregate Concrete ◽  
Mesoscale Modeling ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Element Method

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 Discrete Element Mesoscale Modeling of Recycled Lump Concrete under Axial Compression

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3140 ◽  
Author(s):  
Yong Yu ◽  
Bo Wu
Keyword(s):  
Mechanical Properties ◽  
Axial Compression ◽  
Discrete Element ◽  
Relative Strength ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Ordinary Concrete ◽  
Coarse Aggregates ◽  
Spatial Locations

In the past decade, directly reusing large pieces of coarsely crushed concrete (referred to as demolished concrete lumps or DCLs) with fresh concrete in new construction was demonstrated as an efficient technique for the recycling of waste concrete. Previous studies investigated the mechanical properties of recycled lump concrete (RLC) containing different sizes of DCLs; however, for actual application of this kind of concrete, little information is known about the influence of the spatial locations of DCLs and coarse aggregates on the concrete strength. Moreover, the mechanical responses of such a concrete containing various shapes of DCLs are also not well illustrated. To add knowledge related to these topics, two-dimensional mesoscale simulations of RLC containing DCLs under axial compression were performed using the discrete element method. The main variables of interest were the relative strength of the new and old concrete, the distribution of the lumps and other coarse aggregates, and the shape of the lumps. In addition, the differences in compression behavior between RLC and recycled aggregate concrete were also predicted. The numerical results indicate that the influence tendency of the spatial locations of DCLs and coarse aggregate pieces on the compressive stress–strain curves for RLC is similar to that of the locations of coarse aggregates for ordinary concrete. The strength variability of RLC is generally higher than that of ordinary concrete, regardless of the relative strength of the new and old concrete included; however, variability has no monotonic trend with an increase in the lump replacement ratio. The mechanical properties of RLC in compression are little influenced by the geometric shape of DCLs as long as the ratio of the length of their long axis to short axis is smaller than 2.0. The compressive strength and elastic modulus of RLC are always superior to those of recycled aggregate concrete designed with a conventional mixing method.

Simulation of Uniaxial Compression for Flexible Fibers of Wheat Straw Using the Discrete Element Method

2021 ◽  
Vol 64 (6) ◽  
pp. 2025-2034
Author(s):  
Matthew W Schramm ◽  
Mehari Z. Tekeste ◽  
Brian L Steward
Keyword(s):  
Discrete Element Method ◽  
Wheat Straw ◽  
Young’S Modulus ◽  
Uniaxial Compression ◽  
Material Properties ◽  
Young's Modulus ◽  
Discrete Element ◽  
Flexible Fibers ◽  
Dem Model ◽  
Element Method

HighlightsSimulation of uniaxial compression was performed with flexible fibers modeled in DEM.Bond-specific DEM parameters were found to be sensitive in uniaxial compression.A calibration technique that is not plunger-dependent is shown and validated.Abstract. To accurately simulate a discrete element method (DEM) model, the material properties must be calibrated to reproduce bulk material behavior. In this study, a method was developed to calibrate DEM parameters for bulk fibrous materials using uniaxial compression. Wheat straw was cut to 100.2 mm lengths. A 227 mm diameter cylindrical container was loosely filled with the cut straw. The material was pre-compressed to 1 kPa. A plunger (50, 150, or 225 mm diameter) was then lowered onto the compressed straw at a rate of 15 mm s-1. This experimental procedure was simulated using a DEM model for different material properties to generate a simulated design of experiment (DOE). The simulated plunger had a travel rate of 40 mm s-1. The contact Young’s modulus, bond Young’s modulus, and particle-to-particle friction DEM parameters were found to be statistically significant in the prediction of normal forces on the plunger in the uniaxial compression test. The DEM calibration procedure was used to approximate the mean laboratory results of wheat straw compression with root mean square (RMS) percent errors of 3.77%, 3.02%, and 13.90% for the 50, 150, and 225 mm plungers, respectively. Keywords: Calibration, DEM, DOE, Flexible DEM particle, Uniaxial compression, Wheat straw.

Discrete element method simulations of fracture in concrete under uniaxial compression based on its real internal structure

2017 ◽  
Vol 27 (4) ◽  
pp. 578-607 ◽  
Author(s):  
Jan Suchorzewski ◽  
Jacek Tejchman ◽  
Michał Nitka
Keyword(s):  
Discrete Element Method ◽  
Uniaxial Compression ◽  
Three Dimensional ◽  
Discrete Element ◽  
Cement Matrix ◽  
Two Dimensional ◽  
Compression Tests ◽  
Digital Microscope ◽  
Complex Crack ◽  
Element Method

The paper describes experimental and numerical results of concrete fracture under quasi-static uniaxial compression. Experimental uniaxial compression tests were performed on concrete cubic specimens. Fracture in concrete was detected at the aggregate level by means of three non-destructive methods: three-dimensional X-ray microcomputed tomography, two-dimensional scanning electron microscope and manual two-dimensional digital microscope. The discrete element method was used to directly simulate experiments. Concrete was modelled as a random heterogeneous four-phase material composed of aggregate particles, cement matrix, interfacial transitional zones and macrovoids based on experimental images. Two- and three-dimensional analyses were carried out. In two-dimensional analyses, the real aggregate shape was created by means of clusters of spheres. In three-dimensional calculations, spheres were solely used. A satisfactory agreement between numerical and experimental results was achieved in two-dimensional analyses. The model was capable of accurately predicting complex crack paths and the corresponding stress–strain responses observed in experiments.

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