Eco-friendly concrete: Combining treated wastewater and recycled aggregates.

The concrete industry is a significant consumer of drinking water and natural aggregates, such as sand and gravel. However, the scarcity of water and aggregate resources and the challenges associated with the disposal of construction and demolition waste prompted the exploration of alternative materials. This study investigates the feasibility of incorporating secondary treated wastewater from UASB reactors followed by trickling filters and mixed recycled aggregates as potential alternatives. To assess the viability of these alternatives, the study considered the replacement of 100% potable water with treated wastewater, as well as varying proportions of recycled gravel (20, 40, 60, 80, and 100%) and recycled sand (10, 20, 30, 40, and 100%). Physical and mechanical properties were negatively affected, but it was possible to reach compressive results over 40 MPa and splitting tensile strength over 4 MPa for almost all mixes. Regarding physical properties, the use of alternative materials caused poorer outcomes for density, water absorption, and air-void ratio. The limited magnitude of these detrimental effects indicates the potential of manufacturing concrete with the addition of combined treated wastewater and recycled aggregate as a viable strategy while enhancing reuse practices.

Experimental dataset on the residual performance of fiber-reinforced cementitious composite subjected to high temperature.

The present dataset refers to the research article entitled "A multiscale investigation on the performance improvement of fiber-reinforced cementitious composites after exposure to high temperatures" [1]. Supplementary data on raw materials characterization, temperature recording, mass loss, water absorption, compressive strength, flexural behavior, pull-out response, fiber-matrix interface, and surface, microstructure and hardness of fibers are presented here. The continuous matrix was produced from cementitious grout containing Portland cement, sand, silica fume, superplasticizer, and water. The heating was carried out in an electric oven up to 260 °C. The bending tests was performed for fiber-reinforced cementitious composite (FRCC) with steel fiber contents of 1%, 3%, and 5% by volume, and for non-fibrous matrix. The pull-out test was performed using single fiber embedded in the matrix. The water absorption and axial compression tests was performed for non-fibrous matrix. The fiber-matrix analysis was performed from polished sections of fibers embedded in cementitious matrix. The fiber analysis was performed from steel fibers. The data refer to the residual properties after heating and slow cooling or to the reference condition without heating. The data can help in understanding residual performance of FRCC after exposure to high temperatures and may be useful for developing resilient building materials.

Utilization of Thermally Treated SiC Nanowhiskers and Superplasticizer for Cementitious Composite Production.

Nanomaterials are potential candidates to improve the mechanical properties and durability of cementitious composites. SiC nanowhiskers (NWs) present exceptional mechanical properties and have already been successfully incorporated into different matrices. In this study, cementitious composites were produced with a superplasticizer (SP) and 0-1.0 wt % SiC NWs. Two different NWs were used: untreated (NT-NW) and thermally treated at 500 °C (500-NW). The rheological properties, cement hydration, mechanical properties, and microstructure were evaluated. The results showed that NWs incorporation statistically increased the yield stress of cement paste (by up to 10%) while it led to marginal effects in viscosity. NWs enhanced the early cement hydration, increasing the main heat flow peak. NWs incorporation increased the compressive strength, tensile strength, and thermal conductivity of composites by up to 56%, 66%, and 80%, respectively, while it did not statistically affect the water absorption. Scanning electron microscopy showed a good bond between NWs and cement matrix in addition to the bridging of cracks. Overall, the thermal treatment increased the specific surface area of NWs enhancing their effects on cement properties, while SP improved the NWs dispersion, increasing their beneficial effects on the hardened properties.

Thin Slabs Made of High-Performance Steel Fibre-Reinforced Cementitious Composite: Mechanical Behaviour, Statistical Analysis and Microstructural Investigation.

The present study evaluated the mechanical behaviour of thin high-performance cementitious composite slabs reinforced with short steel fibres. For this purpose, slabs with 1%, 3% and 5% vol. of steel fibres were moulded using the slurry infiltration method. Fibres concentrated in the region subjected to traction during bending stresses. After curing for 28 days, all slabs underwent flexural testing. The slabs with 5% fibre showed significantly higher flexural strength, deflection and toughness compared to those of the control group without reinforcement. The dense fibre distribution, resulting from the production process, led to profiles with multiple random cracks in the region of failure of the slabs as the fibre content increased. The results of the statistical analysis showed the intensity of the correlation between the variables and revealed that the increase of the fibre content significantly influenced the parameters of mechanical behaviour (load, flexural strength, deflection, toughness and toughness factor). Images obtained by optical microscopy aided in understanding the fibre-matrix interface, showing the bonding surface between the constituents of the composite.