Contents lists available at ScienceDirect Cement and Concrete Composites journal homepage: www.elsevier.com/locate/cemconcomp Unified modelling of the temperature effect on the autogenous deformations of cement-based materials Jérôme Carette * , Stéphanie Staquet Université Libre de Bruxelles (ULB), Service BATir, Belgium ABSTRACT Temperature effects are of primary importance for designing concrete structures. Some of the early age temperature effects on the concrete behaviour can be accurately taken into consideration by well-known maturity functions. However, the effect of temperature on the autogenous deformations development is more complex, and results in contradictory evidence. This paper studies the influence of various isothermal curing temperatures from 10 °C to 30 °C on the autogenous deformations of concrete. Binary and ternary binders containing up to 30% of limestone filler and 70% of blast-furnace slag are studied. The amplitude of both the self-desiccation deformation and the early age swelling deformation are observed to decrease with increasing temperature, whatever the binder nature. Mechanisms for this observation are suggested, and a corresponding model is developed. The effect of the binder nature, age and temperature on the autogenous deformations is assessed with this model. Based on this new model, it is shown that the effect of temperature on the autogenous deformation development can be either beneficial or detrimental, depending on the nature of the binder. 1. Introduction Temperature effects are of primary importance for designing con- crete structures. Depending on the whole curing temperature history of the structure, a single concrete composition can result in variable ma- terial properties. This is especially important for massive concrete structures, which undergo important early age temperature variations. More importantly, in such structures, there exists a temperature history gradient, resulting in localized stresses. Such structures require specific engineering knowledge and processes in order to limit the concrete cracking potential [1]. In particular, the sensitivity of concrete to temperature is dependent on the nature of the binder. Mineral additions such as fly ash, blast- furnace slag or limestone filler each have an influence on the hydration kinetics, which is in term affected by temperature in a unique way. Some of these early age effects can be accurately taken into con- sideration. It is the case of most mechanical properties (setting time, elastic modulus, strength, Poisson's ratio), which are known to be mostly affected by temperature through the modification of the hy- dration kinetics. Well known maturity functions, such as the equivalent age expression in Eq. (1) are thoroughly used. It describes the accel- erating effect of a given temperature history T in comparison with a reference temperature T r . R is the universal gas constant (=8.314 J/ mol/K). The apparent activation energy (E a , expressed in kJ/mol) de- scribes the sensitivity of concrete to a temperature variation. ∑ = ⎡ ⎣ − ⎛ ⎝ − ⎞ ⎠ ⎤ ⎦ t e Δt e t E R T T 0 1 1 a r (1) The ultimate values of mechanical properties are also affected by the curing temperature. At higher temperature, the faster hydration results in a less homogenous matrix with coarser pores, and therefore to lower mechanical properties [2,3]. This explains the so-called crossover effect, which generally appears after several days, and is significant for high temperature variations. This effect is therefore not significant at early age for temperature between 10 °C and 30 °C, even for binders with high temperature sensitivity such as in presence of blast furnace slag [4]. For structural applications, the effect of temperature on other properties such as autogenous deformation is generally considered in numerical computations with a classical maturity-based approach, even when significant temperature rises are considered [5,6]. However, the effect of temperature on the delayed deformations (autogenous and drying deformation, creep) is more complex, and results in contra- dictory evidence, in particular for the autogenous deformation devel- opment [7–12]. More specifically, the effect of temperature on the autogenous deformation includes consequences on both the kinetic and the amplitude. The kinetic factor can be taken into account by an evolving apparent activation energy which significantly differs from the mechanical or chemical activation energy. The apparent activation energy with and without mineral additions is typically in the range of 30–60 kJ/mol for compressive strength or heat release measurements https://doi.org/10.1016/j.cemconcomp.2018.08.008 Received 8 March 2017; Received in revised form 12 June 2018; Accepted 13 August 2018 * Corresponding author. E-mail address: jecarett@ulb.ac.be (J. Carette). Cement and Concrete Composites 94 (2018) 62–71 Available online 15 August 2018 0958-9465/ © 2018 Elsevier Ltd. All rights reserved. T