# Development, Characterization, Application and Recycling of Novel Construction Materials
## 2 An Overview of Published Articles  
Recent advancements in the field of cementitious materials have focused on enhancing mechanical properties, sustainability, and durability through innovative approaches, such as incorporating waste materials, innovative additives, and recycled aggregates. One notable approach involves using waste rubber in cement-bound aggregates (CBAs) to reduce their traditionally high stiffness. By developing prediction models for compressive strength and the modulus of elasticity based on non-destructive ultrasonic pulse velocity (UPV) tests, it was found that incorporating rubber not only reduces stiffness but also simplifies the prediction of mechanical properties, especially compressive strength, which does not significantly depend on the curing period [19].  
Additionally, the incorporation of solid-solid phase change materials (SS-PCMs) into cementitious composites was studied due to their heat storage capabilities. While increasing porosity and reducing mechanical strength, SS-PCMs enhanced thermal insulation and shrinkage resistance, demonstrating superior stability over multiple thermal cycles despite their fast carbonation kinetics due to their high porosity. Research on concrete with crystalline hydrophilic additives (CAs) has focused on enhancing resistance to freeze-thaw cycles. Standard air-entraining agents have been found to be effective, but CAs, especially at a 1% dosage, can improve internal damage resistance.  
Another innovative study investigated the role of moisture in CO\({}_{2}\) diffusion and particle cementation in carbonated steel slag. Optimal moisture content was crucial for balancing CO\({}_{2}\) diffusion and particle cementation, enhancing the compressive strength and carbon sequestration capacity of the slag, and thus contributing to the development of effective carbon sequestration materials. These researchers also analyzed the mechanical performance of eco-concrete using recycled concrete aggregates. They found minimal strength decreases and increased permeability with higher concentrations of recycled content, demonstrating the viability of incorporating recycled aggregates into eco-concretes. In examining low-carbon cementitious materials, the effects of external sulfate attack (ESA) were assessed. It was found that a mix of CEM I, slag, and metakaolin exhibited the highest resistance to sulfate attack, while a 100% CEM I mix deteriorated significantly. This highlights the importance of using supplementary cementitious materials to increase durability in sulfate-rich environments [20].  
The use of flaxseed mucilage (FM) as a bio-admixture in ordinary Portland cement was explored. FM delayed the time taken for the cement to set but did not hinder its hydration properties. It increased the cement's porosity and carbonation while reducing its bulk density and thermal conductivity. FM's hygroscopic properties and controlled water release improved the mechanical properties of the cement over time, suggesting that it may confer potential self-healing capabilities. In another study, vegetal fabric-reinforcedcementitious matrix (FRCM) sandwich panels were investigated for their sustainable advantages. When using vegetal fabrics like hemp and sisal in combination with extruded polystyrene cores, these panels showed competitive strength compared to synthetic fibers, with steel connectors providing enhanced stiffness and shear strength [21].  
The recycling of 3D-printed concrete waste as aggregate in new concrete mixtures was also explored. It was found that replacing conventional aggregates with recycled ones from 3D-printed waste at a ratio of up to 67% did not significantly reduce the compressive strength of the concrete and sometimes even improved it, particularly in higher-strength classes like C40/50.  
These studies collectively highlight significant advancements in the field of cementitious materials, with the goal of enhancing mechanical properties, sustainability, and durability.