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Recent advances in the field of cement hydration and microstructure analysis

Cellular concrete review: New trends for application in construction

Printability is a key parameter that affects the application of foam concrete to 3D printing. In this study, the hydroxypropyl methylcellulose (HPMC) and silica fume (SF) were doped into foam concrete as a viscosity modifier and thixotropic agent, and their effects on the stability, rheological properties, and printability of 3D printing foam concrete were investigated. Both HPMC and SF effectively reduced the volume bleeding rate of foam concrete, while HPMC was beneficial for stabilizing the foam, and SF increased the wet density of foam concrete. With the increase in the dosage of HPMC and SF and resting time, the static yield stress, dynamic yield stress, and plastic viscosity of foam concrete increased continuously. SF increased the static yield stress considerably, while HPMC affected the dynamic yield stress and plastic viscosity considerably. It is suggested to combine tanθ and stack height of the printed foam concrete together to evaluate the buildability of 3D printing foam concrete. The suitable ranges of static yield stress, dynamic yield stress and plastic viscosity for 3D printable foam concrete with a wet density from 1550 to 1850 kg/m3 are 1113–1658 Pa, 66.4–230.1 Pa, and 2.08–3.71 Pa s, respectively. The compressive strength of the 3D printed foam concrete with dry density of 1815 kg/m3 in the testing direction Z, Y, and X reached 19.9 MPa, 28.5 MPa and 24.6 MPa, respectively.

Influence of hydroxypropyl methylcellulose and silica fume on stability, rheological properties, and printability of 3D printing foam concrete

3D-printable lightweight foamed concrete and comparison with classical foamed concrete in terms of fresh state properties and mechanical strength

/pdf/investigation-on-rheology-of-oil-well-cement-slurries-3sp0bwmvzm.pdf

Investigation on Rheology of Oil Well Cement Slurries

Rheology of foamed cement

Water Splitting by electrocatalysis is one method of attaining sustainable production of hydrogen as a clean and promising energy source. Previous studies have shown that perovskite can be effective electrocatalyst for overall water splitting. Herein, double perovskites being highly stable structures have been reported to perform exceptionally in harsh electrochemical environments. The Praseodymium (Pr) doped Strontium Titanium Ferrite (STF) electrocatalyst was tested as an electrocatalyst for water splitting with conductive nickel foam. Pr was doped both on A and B sites of the STF’s double perovskite structure, and the SrTiFe 0.9 Pr 0.1 O 6-δ (STFP01) showed the best results with an oxygen evolution reaction (OER) overpotential of 277.6 mV @ 5 mV/s and a hydrogen evolution reaction (HER) overpotential of 182.4 mV @ 5 mV/s with low Tafel slopes of 73 mV/dec and 77 mV/dec, respectively. The sponge-like structure of Pr-doped STF exhibits excellent potential to be a viable electrocatalyst while providing a stable structure. • Praseodymium doped double perovskite developed for hydrogen production. • The electrocatalysts were tested on 3-electrode and 2-electrode assemblies. • The material exhibited excellent performance for water splitting. • Performance can be attributed to the porous structure of the material. 

Praseodymium-doped Sr2TiFeO6-δ double perovskite as a bi-functional electrocatalyst for hydrogen production through water splitting

Nondestructive characterization of solid oxide fuel cell (SOFC) materials has drawn attention owing to the advances in instrumentation that enable in situ characterization during high-temperature cell operation. X-ray photoelectron spectroscopy (XPS) is widely used to investigate the surface of SOFC cathode materials because of its excellent chemical specificity and surface sensitivity. The XPS can be used to analyze the elemental composition and oxidation state of cathode layers from the surface to a depth of approximately 5–10 nm. Any change in the chemical state of the SOFC cathode at the surface affects the migration of oxygen ions to the cathode/electrolyte interface via the cathode layer and causes performance degradation. The objective of this article is to provide a comprehensive review of the adoption of XPS for the characterization of SOFC cathode materials to understand its degradation mechanism in absolute terms. The use of XPS to confirm the chemical stability at the interface and the enrichment of cations on the surface is reviewed. Finally, the strategies adopted to improve the structural stability and electrochemical performance of the LSCF cathode are also discussed.

/pdf/a-review-of-x-ray-photoelectron-spectroscopy-technique-to-1fl7918e.pdf

U.M. Khan

Papers

Rheology of foamed cement

Praseodymium-doped Sr2TiFeO6-δ double perovskite as a bi-functional electrocatalyst for hydrogen production through water splitting

A Review of X-ray Photoelectron Spectroscopy Technique to Analyze the Stability and Degradation Mechanism of Solid Oxide Fuel Cell Cathode Materials