This special issue entitled “Quantitative visualization testing techniques applied to civil engineering structures and materials” follows the organization of a series of thematic workshops entitled “Techniques d'Imagerie pour la Caracté risation des Matériaux et des Structures du Génie Civil” (image-based techniques for the characterization of materials and structures in civil engineering). The different editions took place in France in the cities of Clermont-Ferrand (March 20–21, 2014), Grenoble (March 10–11, 2016) and Champs-sur-Marne (April 4–5, 2019), bringing together about 50 PhD students, post-doc, early career or senior researchers who gave oral or poster presentations in the field of the experimental mechanics applied to civil engineering structures and materials. The present special issue illustrates how much the quantitative measurement experimental techniques in that research field have progressed and diversified within the last decade. Among the quantitative testing techniques used in the presented papers, one may want to highlight the various full-field or multipoint measurement methods: 2D and 3D Digital Image Correlation, Grid method, Particle Image Tracking, Particle Imagery Velocimetry, Digital Volume Correlation, Sampling moiré, Reflection photoelasticity, Optical fibre sensors, among others. These test methods are applied to heterogeneous materials: concrete, fibre-reinforced concrete, textile-reinforced concrete, granular materials, etc., from the microscopic or nanoscopic scale to the metre or decameter scale when applied to concrete bridges or masonry walls in this present special issue. Applications concern various environmental conditions such as high temperatures, different moisture contents, or loading conditions like high strain-rates testing. The underlying damage mechanisms are investigated by different methods like X-ray microtomography, synchrotron radiation or rapid neutron tomography. The wealth of experimental evidence brings better understanding of the mechanical behaviour of these civil engineering materials and structures and leads to substantial progress in the identification and the development of predictive modelling using Finite or Discrete Element, damage, cohesive zone or mixed-mode fracture models. We would like to acknowledge the contribution from many people which made this special issue possible. We wish to express our warm thanks to our reviewers for their time and efforts in reviewing papers and the authors for their work in submitting and revising their manuscript. Our gratitude also goes to Pr. Fabrice Pierron, former editor-in-chief of STRAIN Journal, for his guidance and support throughout the entire process. Wishing you a pleasant and inspiring reading,