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Acoustic emission (AE) measurements performed during the compressive loading of concrete samples with three different microstructures (aggregate sizes and porosity) and four sample sizes revealed that failure is preceded by an acceleration of the rate of fracturing events, power law distributions of AE energies and durations near failure, and a divergence of the fracturing correlation length and time towards failure. This argues for an interpretation of compressive failure of disordered materials as a critical transition between an intact and a failed state. The associated critical exponents were found to be independent of sample size and microstructural disorder and close to mean-field depinning values. Although compressive failure differs from classical depinning in several respects, including the nature of the elastic redistribution kernel, an analogy between the two processes allows deriving (finite)-sizing effects on strength that match our extensive dataset. This critical interpretation of failure may have also important consequences in terms of natural hazards forecasting, such as volcanic eruptions, landslides, or cliff collapses. PACS: 62.20. 64.60.av, 89.75.Da, 83.80.Ab Classical fracture and failure theoretical frameworks or criteria, such as Griffith theory or the Coulomb failure criterion, do not consider material disorder. Consequently, they predict an abrupt global failure, without any precursory phenomenon. In that sense, failure can be interpreted as a firstorder transition from an intact to a failed state, as Griffith theory was inspired by the classical theory of nucleation [1,2]. Materials heterogeneity has been however considered for a long time, especially to account for failure strength variability and associated size effects [3]. Nevertheless, this weakestlink approach is based on strong assumptions such as the absence of mechanical interactions between defects and between rupture events, or a global failure dictated by the activation of the largest flaw (the weakest-link). These assumptions might appear reasonable for weakly disordered materials under tension, especially in the case of a pre-existing large crack or notch. However, in case of large enough disorder, the quasi-static propagation of such a crack can be interpreted as a dynamical critical transition [4,5]. The limitations of these classical frameworks appear even clearer for highly disordered systems without macro-scale heterogeneities [6] and/or loading conditions stabilizing crack propagation, such as compression (through the presence of friction). In those cases, it is known for a long time that failure is a process, involving the nucleation, interaction, propagation and coalescence of many microcracks [7,8], hence characterized by precursory phenomena. The presence/absence of

The characteristic compressive strength is one of the most important material property used in structural design and quality control of concrete. Here we show that the estimation of this characteristic strength following classical standard rules (e.g. EN 1992 or ACI-318) is sample size dependent, i.e. is not a characteristic of the material. From an extensive experimental dataset, an analysis of published strength data, and an interpretation of compressive failure as a critical phase transition from an intact to a failed state, we show that the compressive strength of concrete is characterized by a non-vanishing asymptotic mean strength, , but a vanishing associated variability towards very large system sizes. Consequently, the asymptotic strength can be regarded as the genuine characteristic compressive strength of concrete. Based on this, we propose a new procedure to evaluate this genuine characteristic strength as well as to check the conformity of concrete with strength requirements.

Crackling dynamics is characterized by a release of incoming energy through intermittent avalanches. The shape, i.e. the internal temporal structure of these avalanches, gives insightful information about the physical processes involved. It was experimentally shown recently that progressive damage towards compressive failure of quasi-brittle materials can be mapped onto the universality class of interface depinning when considering scaling relationships between the global characteristics of the microcracking avalanches, such as energy and duration. Here we show, for three concrete materials prepared from three different mixtures, and from a detailed analysis of the acoustic emission waveforms generated by microcracking events, that the shape of these damage avalanches is strongly asymmetric, characterized by a very slow decay. This remarkable asymmetry, at odds with mean-field depinning predictions, could be explained, in these quasi-brittle materials, by retardation effects induced by enhanced viscoelastic processes within a fracture process zone generated by the damage avalanche as it progresses.

The control of the concrete temperature to prevent cracking can be viewed as principal goal in the design and construction of mass concrete. This paper researched on a novel technique for minimizing both the difference and the peak value of the temperature in mass concrete. Following this technique, the mass concrete is divided horizontally into two parts of different concrete mixtures but having the same strength grade. While the upper part is the normal heat concrete, the lower part can be considered as the low heat concrete which generate lower hydration heat than the upper part does. The influences of (i) concrete proportions of the layers; and (ii) thickness of the upper layer on the thermal behavior in mass concrete are two important aspects of the technique. Therefore, these two points represent important objectives of our present research. For this purpose, some numerical simulations with finite element method (FEM) and an in-situ experiment on a mass concrete block were performed. As a result, the simulated temperature field was validated by comparing with the experimental result and the principles of layers’ mixtures and thickness were drawn.

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This data article provides a series of 492 stress-strain curves and compressive strength values obtained under the uniaxial compression of concrete samples fabricated from three different normal-weight concrete mixtures with four different cylindrical sample sizes ranging from 40 × 80 mm to 160 × 320 mm. These data are related to two research articles: “Revisiting statistical size effects on compressive failure of heterogeneous materials, with a special focus on concrete” (Vu et al., 2018) [1] and “Revisiting the concept of characteristic compressive strength of concrete” (Vu et al., 2020) [2] . In those papers, the strength values were used to (i) analyze and interpret statistical size effects on compressive strength of concrete (in ref. [1] ), and (ii) discuss and evaluate the genuine characteristic compressive strength of concrete when size effects on strength are taken into account (in ref. [2] ). This dataset could be reused for other statistical analyses on the mechanical behavior of concrete (e.g. elastic and strength properties) and associated possible mixture or size effects. In addition, the characteristic properties of the hardened concrete samples such as the apparent density, the moisture content, the modulus of elasticity as well as the internal microstructures are also provided.

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