Investigation of crack development in a fairfaced replacement screed based on fiber-reinforced concrete

In the present study, a design concept for unreinforced, cement-bound concrete floors
is presented. The work concentrates on cracking caused by shrinkage of the concrete
used. The central components of the work are a numerical model (Finite element model)
which, taking into account all time-dependent material parameters and with the aid of a
simple calculation approach, is able to predict crack paths on sharp edges. In addition,
with the help of the model, it is possible to simulate the curling of the corners of a float
mounted concrete floor.
For this purpose, the required material parameters (static elastic modulus, uniaxial tensile
strength) were investigated under laboratory conditions and compared with prognosis
values of an available prognosis software and with the analytical prognosis approach
of DIN EN 1992-1-1: 2011-01.
In a first step, the crack formation and crack development on a small, H-shaped concrete
sample were examined and a crack path was calculated using a first numerical approach.
This first numerical approach was subsequently validated on large-scale surfaces. On the
basis of the large-scale experiments, the numerical model was further developed with regard
to curling of concrete floors.
All experiments were calculated with the approach of element failure method (EFM)
using the commercial finite element software ANSYS.
The design concept is completed by a parameter study. By means of this parameter
study, it is possible to identify the parameters which decisively influences cracking.
The present work thus makes an important contribution to the numerical modelling
of damage in unreinforced concrete structures.