High and Ultra-high Performance Concretes: A Solution to Reinforced Concrete Durability under Harsh Climate of Arabian Gulf

Reinforced concrete (RC) infrastructure in the Arabian Gulf region deteriorates under severe environmental conditions after only short service life. To overcome this problem, it is imperative to employ high-quality concretes and reinforce them with rebars that are corrosion resistant. This paper investigates the durability performance of newly developed high performance concretes (HPC) and ultra-high performance concretes (UHPC). The HPC and UHPC were manufactured using locally available materials in Qatar without employing any special treatment. The durability characteristics of HPC and UHPC in comparison to a normal strength concrete (NSC) were determined. Durability indicators such as concrete resistivity, sorptivity, porosity and resistance to chloride permeability were evaluated in order to access the durability of these concretes. These parameters were also compared to the concrete core samples taken from 30 to 50 years old RC structures in Doha city. The electrical resistivity of HPC and UHPC was 11 and 20 times higher than NSC, respectively. Sorptivity was 2 and 3 times less than NSC, respectively for HPC and UHPC. While the porosity of HPC and UHPC was 2.45 and 1.43% respectively. These newly fabricated concretes showed higher performance in durability testing than the concretes from real structures. With such attributes, the UHPC will be a useful tool in arresting the rapid deterioration of RC structures especially under harsh-climatic conditions of the Arabian Gulf.The funding for this research was provided by the National Priorities Research Program of the Qatar National Research Fund (a member of the Qatar Foundation) under the award no. NPRP 7-410-2-169. The statements made herein are solely the responsibility of the authors and do not necessarily reflect the opinions of the Sponsor

Thermal insitu analyses of multicomponent pyrophosphate cathodes materials

Development of secondary batteries based on abundant and inexpensive elements are vital. Amongvarious alternative choices, sodium-ion batteries (NIBs) are promising because of plentiful resourcesand low costs of sodium metal. Different types of cathode materials for NIBs have been designed andstudied to meet the challenging requirements. Among them pyrophosphate cathodes have shownpromising electrochemical performance and thermal stability in sodium ion batteries (SIBs). In thepresent study, we report synthesis and thermal behavior of a novel Na2Fe0.33Mn0.33Co0.33P2O7 cathodematerial developed for sodium rechargeable batteries. The material was developed through solid stateprocess. The structural analysis of Na2Fe0.33Mn0.33Co0.33P2O7 revealed that the substitution ofmulticomponent transition metals have achieved triclinic crystal structure (P1 space group). TGA/DTAand thermal in-situ XRD analyses (25~550oC) confirm decent thermal stability of this material up to550oC even in the desodiated state with negligible weight loss (5%). Owing to its promising thermalstability, Na2Fe0.33Mn0.33Co0.33P2O7, would be an attractive cathode for sodium ion batteries.Scopu

Cerium oxide loaded with Gum Arabic as environmentally friendly anti-corrosion additive for protection of coated steel

The depreciation of assets and safety threats because of corrosion has forced to develop eco-friendly and smarter corrosion protection strategies. In this study, natural Gum Arabic (GA) was used as a corrosion inhibitor and loaded into cerium oxide nanoparticles (CONPs) to develop an environment-friendly additive for corrosion protection of coated steel in the marine environment. This additive was uniformly dispersed into an epoxy formulation that was used to protect steel plates. Epoxy coatings containing CONPs, without GA, were also prepared as reference. High-Resolution Transmission Electron Microscopy (HR-TEM) and Fourier Transform infrared spectroscopy (FTIR) revealed the successful loading of GA into the CONPs. Thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET) techniques confirmed approximately ⁓30.0 wt% loading of GA into the CONPs. Electrochemical impedance spectroscopy (EIS) demonstrated the anticorrosion properties of the epoxy coatings modified with the GA loaded CONPs when compared to reference coatings. The corrosion protection mechanism postulates that GA loaded CONPs act as a filler material for epoxy coating and it can also aid the recovery of the protective properties of the epoxy coating leading to the formation of a stable protective layer.This publication was made possible by NPRP11S-1226-170132 from Qatar National Research Fund (a member of the Qatar Foundation). Statements made herein are solely the responsibility of the authors. The authors would like to thanks to the Central Laboratories Unit (CLU), Qatar University, 2713, Doha, Qatar for FE-SEM, and HR-TEM analyses. Authors from Portugal acknowledge FCT for the additional funding under the project UIDB/00100/2020 and UIDP/00100/2020. Open Access funding provided by the Qatar National Library. The raw data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.Scopu