Introduction: Metakaolin (MK) is used as supplementary cementitious material to reduce the CO 2 footprint of Portland cements. However, early hydration cement (OPC) often retarded due its use. The present work investigates mechanisms this retardation. Focus laid on interaction MK with main clinker phase C 3 S (Ca SiO 5 , pure form alite) that known govern kinetics OPC. Methods: Hydration reacti...

Triphenylgermyl-lithium in diethyl ether/THF did not react with Al2Me6 to form [(Ph3Ge)AlMe3]Li(THF)n. Addition of TMEDA to this solution yielded crystalline Ph3GeLi(THF)TMEDA. The reaction of Ph3GeLi in diethyl ether/hexane solution with H3Al-NMe3 in diethyl ether/THF generated [Ph3GeAlH3]Li(THF)4 while the reaction with Me2AlCl led to Ph3GeAlMe2(OEt2) and the trigermyl-aluminate [(Ph3Ge)3AlMe...

The structural behavior of a chromate aluminate sodalite, Ca8[Al12O24](CrO4)2, at room pressure and on heating from 463 to 982°C was determined by using in situ synchrotron X-ray powder-diffraction data [ = 0.91997(4) Å] and Rietveld refinements. The sample was heated at a rate of about 9.5°C/min., and X-ray traces were collected at intervals of about 17°C. The structure at 463°C is a modulated...

The thermal conductivity of a series of complex aluminates, RE2SrAl2O7, with different rare-earth (RE) ions, has been measured up to 10001C. There is a strong dependence on the atomic number of the RE ion, ranging from an approximately 1/T dependence for the lanthanum strontium aluminate to an almost temperature-independent behavior of the dysprosium strontium aluminate. The latter conductivity...

OBJECTIVE The purpose of this study was to investigate and compare the crystalline structures of recently released MTA Plus (MTA-P), MTA Angelus (MTA-A), DiaRoot BioAggregate (BA) by X-ray diffraction (XRD) analysis. MATERIALS AND METHODS Phase analysis was carried out on powder and set forms of tested materials. The powder specimens placed into sample holders that were packed with a glass sl...

In the present work the internal sulfate attack on pastes made from pure clinker phases was studied. Two binders were produced: (a) a binder with 2% C3A and 18% C4AF content; (b) a binder with 10% C3A and C4AF content each. Gypsum was used as the sulfate bearing compound, while calcium carbonate added to differentiate the binders produced. The phases formed were identified by XRD analysis. The ...

External sulfate attack of concrete is a major problem that can appear in regions where concrete is exposed to soil or water containing sulfates, leading to softening and cracking of the concrete. Therefore, it is important that materials selection and proportioning of concrete in susceptible regions be carefully considered to resist sulfate attack. American Society for Testing Materials (ASTM)...

Mixtures of rare-earth zirconates and aluminates containing Y or + Gd that form a two-phase garnet–fluorite mixture exhibit much slower sintering than pure fluorite at 1400°C. An equivalent Y-free, Gd-containing composition forms perovskite aluminate instead garnet showed faster densification after the metastable decomposes. At 1500°C, Y-free sample also fastest initial rate, whereas there was ...