A study on temperature rise in heterogeneous cement materials using the FE2 method

Resumo

The hydration reaction of ordinary Portland cement (OPC) is a complex process that initiates as soon as
the OPC meets water. During this process, hydration products are formed, changing the thermal and mechanical
properties and releasing heat. Massive structures of cement-based materials (CBMs) such as damns, bridges or
foundations of large buildings, tend to present a substantial increase of temperature due the great amount of heat
generated by the hydration reaction which together with the mechanisms of heat transfer trough the boundaries
can cause significative high temperature gradients and nonhomogeneous dilation/shrinkage, leading to cracking

during the early ages. To prevent these damages, the hydration process can be numerical predicted using multi-
scale models, once that the thermochemical response and increasing of temperature of the macroscale depends on

the microstructural changes due the hydration reaction. In this paper, the recent computational homogenization
approach direct FE2 method (dFE2) is applied to predict the adiabatic and semi-adiabatic temperature rising in
mortars, assuming a simple chemical kinetics law to describe the hydration of the OPC and several sand fractions.
The dFE2 method is a monolithic method in which the passage information macro to micro and micro to macro
is not required as in the usual FE2. Instead, by using the concepts of multipoint constrains the macro and micro

discretization are linked allowing the imposition of the boundary conditions (linear, periodic, etc.) to the represen-
tative volume element (RVE). The implementation was made on ABAQUS finite element software by developing

particular user-subroutines used to determine state of cure of cement-based materials. A example of macrostructure
under semi-adiabatic conditions, exchanging heat with its surroundings by convection, is presented. The results
show the adequacy of the proposed approach.