Fracture in concrete structures is generally accompanied by progressive cracking. This process is very complex and can be identified by associated crack parameters such as crack openings and crack length. These parameters are the direct indicators of the local failure in the material microstructure and can completely describe the fracture process of the concrete structure. The purpose of this article is to monitor experimentally the crack openings in geometrically similar concrete beams with different sizes. An experimental approach is used to estimate the effective crack length from the crack opening profile. For this, the digital image correlation technique is applied on the specimen surface to capture crack propagation. Size effect on the crack propagation is also investigated.

This paper presents a study on cracking risk due to shrinkage of self-compacting concrete (SCC). Cracking of SCC was investigated through a comparison of material properties, such as shrinkage, modulus of elasticity, creep, and fracture parameters, between SCC mixtures and ordinary concrete (OC) mixtures. Restrained shrinkage tests (ring tests) were also performed on the same mixtures. Numerical simulations were then used to assess the correlation between material properties and results of restrained shrinkage tests. SCC and OC were found to have equivalent shrinkage cracking tendency, provided that compressive strength is kept the same and that SCC has adequate segregation resistance.

Geopolymers have gained much interest recently as a promising alternative to cementitious materials in some applications. However, research is still needed to use this technology for soil reinforcement grouts. The specifications of grouts mainly consist in rheological properties, strength and permeability. Grouting actually requires a low viscosity, and thus higher water content. The influence of relatively high water content on the other properties of the material, i.e. strength and microstructure, has been investigated. This effect highly depends on the concentration of the activator (sodium silicate solution) and the precursor (metakaolin, fly ash or blast furnace slag) associated with the activator. This paper deals with the main effects of high water content on the microstructure and mechanical properties of the materials, looking at physical and chemical aspects. Scanning electron microscopy and chemical phase analysis were used to highlight the nuances that are related to the precursors used, especially regarding the microstructure and kinetics of the geopolymerisation process.