The aim of this study is analyzing the self-healing effect of a crystalline admixture in four types of 11 environmental exposure comparing with a reference concrete. Healing was studied by means of permeability tests on 12 cracked specimens and physical closing of the crack was observed by optic microscope and quantified through crack 13 geometrical parameters. The studied crack openings were under 300 μm and the time set for healing was 42 days. The 14 results show a different healing behavior depending on the exposure and the presence of the crystalline admixture, 15 demonstrating that the presence of water is necessary for the healing reactions. 16

This paper analyzes the self-healing properties of early-age concretes, engineered using a crystalline admixture (4% by the weight of cement), by measuring the permeability of cracked specimens and their crack width. Two concrete classes (C30/37 and C45/55) and three healing exposure conditions have been investigated: water immersion at 15 °C, at 30 °C and wet/dry cycles. Specimens were pre-cracked at 2 days, to values of crack width in the range of 0.10–0.40 mm. The results show almost perfect healing capability for specimens healed under water at 30 °C, better than for specimens healed under water at 15 °C, while insufficient for the wet/dry exposure

No abstract

No abstract

ElsevierCuenca Asensio, E.; Serna Ros, P. (2013) AbstractHollow core slabs (HCS) are usually precast by extrusion and it is not easy to place stirrups; thus, it is difficult to guarantee shear resistance in some cases. This paper describes an experience using fiber- Different failure modes took place. Some of the main conclusions drawn were that fibers act as shear reinforcement, HCS with fibers achieved greater loads than HCS without fiber reinforcement and with a more ductile behavior.

No abstract

This paper presents the results are shown of a thorough characterization of the selfhealing capacity of High Performance Fibre Reinforced Cementitious Composites (HPFRCCs). The capacity of the material will be investigated to completely or partially re-seal the cracks, as a function of its composition, maximum crack width and exposure conditions. The analysis will also consider different flow-induced alignments of fibres, which can result into either strain-hardening or softening behaviour, whether the material is stressed parallel or perpendicularly to the fibres, respectively. Beam specimens, initially pre-cracked in 4-point bending up to different values of crack opening, were submitted to different exposure conditions, including water immersion, exposure to humid or dry air, and wet-and-dry cycles. After scheduled exposure times, ranging from one month to two years, specimens were tested up to failure according to the same test set-up employed for pre-cracking. Outcomes of the self-healing phenomenon, if any, were analyzed in terms of recovery of stiffness, strength and ductility. In a durability-based design framework, self-healing indices quantifying the recovery of mechanical properties were also defined and their significance crosschecked.

No abstract