Numerical simulation of fresh concrete flow: insight and challenges

Ksenija Vasilic,Annika Gram,Jon Elvar Wallevik

doi:10.21809/rilemtechlett.2019.92

Ksenija Vasilic, Annika Gram + Show 1 more

Open Access

https://doi.org/10.21809/rilemtechlett.2019.92

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Abstract

Recent developments in concrete technology are advancing into a scientific-based approach, where both experimental and numerical simulations are utilised to achieve an optimum mix design and an effective placement into formwork at the jobsite. Since the load carrying capacity and service life of concrete structures is fully dependent on the success of the placement process, researchers all over the world have started to work on casting prediction tools using different numerical software. However, a lot of work is still to be done in order to properly model the large-scale flow processes. This is because fresh concrete is a very complex material and its simulations involve complex material models and extensive computations. An exact material model of fresh concrete does not exist, and the researchers use diverse approximations to depict concrete flow. In this paper, we identify the main challenges for modelling fresh concrete and review the existing simulation methods. The advantages, disadvantages and application fields are discussed, including future perspectives for having numerical tools for practical use.

Highlights

The numerical simulations of fresh concrete flow have been increasing in popularity in the last decade [1,2,3,4,5,6,7,8]
There are several areas of concrete technology, where numerical flow simulations are applied. They can be used in computer‐aided rheometry and testing, enabling to better understand the material in the fresh state. This is of crucial interest for the modern flowable concretes, which must fulfil complex requirements in the fresh state and require additional tools to control and measure their rheology [13, 14]
We will give some examples of numerical simulations of the presence of grains, fibres or reinforcement in the concrete flow

Summary

Introduction

The numerical simulations of fresh concrete flow have been increasing in popularity in the last decade [1,2,3,4,5,6,7,8]. The compared CFD and DEM techniques gave very similar results and provided a good match with the analytical solutions [5] Both the continuous and the discrete approach have their limitations, and the choice of the method for the specific application depends on the type of concrete, on the process itself and on the scale of observation [59] (see Figure 7). DEM continuum assemble of particles fast, numerical complexity is moderate, input parameters can be measured simplification of material, no particles able to predict rotation and movement of single particle processor intensive, number of particles limited, numerical complexity scale of observation macroscopic particle scale type of concrete process flowable concretes slump concretes rheometry, basic tests, casting, pumping, segregation mixing, de‐airing, blocking, segregation, sedimentation

Advanced methods

Simulation of particle segregation

Findings

Simulation of shear‐induced particle migration