Self-healing concrete holds promising benefits to reduce the cost for concrete maintenance and repair as cracks are autonomously repaired without any human intervention. In this study, the application of a carbonate precipitating bacterium Bacillus sphaericus was explored. Regarding the harsh condition in concrete, B. sphaericus spores were first encapsulated into a modified-alginate based hydrogel (AM-H) which was proven to have a good compatibility with the bacteria and concrete regarding the influence on bacterial viability and concrete strength. Experimental results show that the spores were still viable after encapsulation. Encapsulated spores can precipitate a large amount of CaCO3 in/on the hydrogel matrix (around 70% by weight). Encapsulated B. sphaericus spores were added into mortar specimens and bacterial in-situ activity was demonstrated by the oxygen consumption on the mimicked crack surface. Specimens with free spores added showed no oxygen consumption. This indicates the efficient protection of the hydrogel for spores in concrete. To conclude, the AM-H encapsulated carbonate precipitating bacteria have great potential to be used for crack self-healing in concrete applications.

Nowadays, a wide range of wound dressings is already commercially available. The selection of the dressing is of paramount importance as inappropriate wound management and dressing selection can delay the wound healing process. Not only can this be distressing for the patient, but it can also contribute to complications such as maceration and subsequent infection. Many researchers are targeting the design of dressings with superior properties over existing commercial dressings. However, reported results in the state-of-the-art are rarely benchmarked against commercial dressings. The aim of this study was to determine several characteristics of a large variety of the most frequently used commercial wound dressings, providing an overview for both practitioners and researchers. For this comparative study, 11 frequently used commercial wound dressings were selected, representing the different types. The morphology was studied using scanning electron microscopy. The dressings were characterized in terms of swelling capacity (water, phosphate buffered saline and simulated wound fluid), moisture vapour transmission rate (MVTR) and moisture uptake capacity (via dynamic vapour sorption) as well as mechanical properties using tensile testing and texturometry. The selected dressings showed distinctive morphological differences (fibrous, porous and/or gel) which was reflected in the different properties. Indeed, the swelling capacities ranged between 1.5 and 23.2 g/g (water), 2.1 and 17.6 g/g (phosphate buffered saline) or 2.9 and 20.8 g/g (simulated wound fluid). The swelling capacity of the dressings in water increased even further upon freeze-drying, due to the formation of pores. The MVTR values varied between 40 and 930 g/m²/24 h. The maximal moisture uptake capacity varied between 5.8% and 105.7% at 95% relative humidity. Some commercial dressings exhibited a superior mechanical strength, due to either being hydrophobic or multi-layered. The present work not only offers insight into a valuable toolbox of suitable wound dressing characterization techniques, but also provides an extensive landscaping of commercial dressings along with their physico-chemical properties, obtained through reproducible experimental protocols. Furthermore, it ensures appropriate benchmark values for commercial dressings in all forthcoming studies and could aid researchers with the development of novel modern wound dressings. The tested dressings either exhibited a high strength or a high swelling capacity, suggesting that there is still a strong potential in the wound dressings market for dressings that possess both.

Cracking is a major concern in building applications. Cracks may arise from shrinkage, freeze/thawing and/or structural stresses, amongst others. Several solutions can be found but superabsorbent polymers (SAPs) seem to be interesting to counteract these problems. At an early age, the absorbed water by the SAPs may be used to mitigate autogenous and plastic shrinkage. The formed macro pores may increase the freeze/thaw resistance. The swelling upon water ingress may seal a crack from intruding fluids and may regain the overall water-tightness. The latter water may promote autogenous healing. The use of superabsorbent polymers is thus very interesting. This review paper summarizes the current research and gives a critical note towards the use of superabsorbent polymers in cementitious materials.

Superabsorbent polymers (SAP) are a new, promising class of chemical admixtures which offer new possibilities in respect of influencing the properties of cement-based materials in the fresh, hardening, and hardened states. Much research work has been done in the last two decades to set the stage for introducing this truly multipurpose agent into the practice of construction. In particular, three RILEM Technical Committees: 196-ICC, 225-SAP and 260-RSC contributed considerably to the related progress by coordinating and combining the efforts of international experts in the field. The major product of the RILEM TC 225-SAP work was the State-of-the-Art Report published in 2012. This comprehensive document covered all topics relevant to the application of SAP as a concrete admixture. Since then further important progress has been made in understanding the working mechanisms of SAP in concrete and the effects of SAP-addition on various concrete properties. The article at hand presents an update on the state-of-the-art and is the concluding document delivered by the RILEM TC 260-RSC.