This study presents the application of encapsulated expansive powder minerals (magnesium oxide, bentonite and quicklime) for self-healing of cement-based mortars. A system of concentric glass macrocapsules was used to envelope the expansive minerals (outer capsule) and water (inner capsule). Mortar samples containing concentric macrocapsules with different mineral combinations were cracked and healed under three different curing regimes; ambient conditions, high humidity exposure and immersed in water. Self-healing was assessed based on visual crack sealing, mechanical strength recovery and improvement in durability investigated by means of capillary sorption tests. Micro-structural analysis of the healing materials was investigated using FT-IR, XRD and SEM-EDX for exploring self-healing kinetics. Immersed in water yielded the optimum healing efficiency with ~95% crack sealing and ~25% strength recovery in 28 days. Data showed an increasing trend in 56 days for both crack sealing and load recovery. The improvement in terms of capillary absorption of healed samples was also significant after 28 days of healing. Self-healing kinetics revealed that the expansive minerals were hydrated in the initial healing period and slowly carbonated over time until the peripheral crack zone became adequately water tight.This work was supported by the EPSRC [grant number EP/K026631/1 IDB. 600014435] and Islamic Development Bank (IDB)

Due to the strong in-plane but weak out-of-plane bonding, it is relatively easy to separate nanosheets of two-dimensional (2D) materials from their respective bulk crystals. This exfoliation of 2D materials can yield large 2D nanosheets, hundreds of micrometers wide, that can be as thin as one or a few atomic layers thick. However, the underlying physical mechanisms unique to each exfoliation technique can produce a wide distribution of defects, yields, functionalization, lateral sizes, and thicknesses, which can be appropriate for specific end applications. The five most commonly used exfoliation techniques include micromechanical cleavage, ultrasonication, shear exfoliation, ball milling, and electrochemical exfoliation. In this review, we present an overview of the field of 2D material exfoliation and the underlying physical mechanisms with emphasis on progress over the last decade. The beneficial characteristics and shortcomings of each exfoliation process are discussed in the context of their functional properties to guide the selection of the best technique for a given application. Furthermore, an analysis of standard applications of exfoliated 2D nanosheets is presented including their use in energy storage, electronics, lubrication, composite, and structural applications. By providing detailed insight into the underlying exfoliation mechanisms along with the advantages and disadvantages of each technique, this review intends to guide the reader toward the appropriate batch-scale exfoliation techniques for a wide variety of industrial applications.