Andrea Crețu

Technische Universität Ilmenau | TUI · Institute of Physics

Osteoarthritis (OA) as the main degenerative disease of articular cartilage in joints is accompanied by structural and compositional changes in the tissue. Degeneration is a consequence of a reduction of the amount of macromolecules, the so-called proteoglycans, and of a corresponding increase in water content, both leading to structural weakening...

The present work systematically investigates the influence of silica fume and organosilane addition on the hydration dynamics and the capillary pore formation of a cement paste. The cement samples were prepared with two water-to-cement ratios with increasing amounts of silica fume and of (3-Aminopropyl)triethoxysilane (APTES) organosilane. Low-fiel...

The hydration process of four different cement-based materials at different depths inside the sample was investigated using localised nuclear magnetic resonance relaxation measurements. All the samples are based on white Portland cement (CEM I 42.5 R), with a water-to-cement ratio of 0.5. One sample is a simple cement paste and the other three addi...

The influence of silanised silica fume addition on the pore size distribution and wettability of white cement paste was investigated using T1–T2 correlation nuclear magnetic resonance (NMR) relaxometry. Surface silanisation of silica fume particles was achieved by the hydrolysis reaction of APTES (3-Aminopropyltriethoxysilane) and condensation of t...

Fast Field Cycling (FFC) nuclear magnetic resonance (NMR) relaxometry is used to monitor the influence introduced on the hydration process by the addition of silica fume in a cement paste mixture, prepared with white Portland cement. The FFC relaxometry technique was implemented due to its sensitivity to a wider range of molecular motions, which gi...

Varying the amount of water in a concrete mix will influence its final properties considerably due to the changes in the capillary porosity. That is why a non-destructive technique is necessary for revealing the capillary pore distribution inside hydrated cement based materials and linking the capillary porosity with the macroscopic properties of t...

Available online xxxx Nuclear Magnetic Resonance (NMR) relaxation studies of liquids confined inside cement samples mostly refer to water molecules and saturated pores. Here we extend these studies to the ethanol and cyclohexane molecules partially saturating a white cement paste. The two filling liquids were selected as representatives of polar an...

Nuclear magnetic resonance (NMR) relaxometry is used here as a noninvasive tool to monitor the influence introduced by the addition of 3-Aminopropyltriethoxysilane (APTES) on the hydration of pure cement paste and a cement paste containing quartz powder. It is observed extension of the dormancy stage up to 12 h in the presence of the aminosilane an...

It is known that by adding a small amount of nanoparticles to the cement-based materials a strong influence on the workability, strength and durability is obtained. These characteristics of the material are fundamentally determined by the hydration process taking place after mixing the cement grains with water. In the present study the influence in...

The inflence introduced by the addition of nano-silica with silanized surfaces on the hydration process was investigated using low-fild nuclear magnetic resonance (NMR) relaxometry. The cement samples were prepared using gray cement at a water-to-cement ratio of 0.4 and a 5% addition of nanosilica. The surface of the nanoparticles was modifid using...

Adding silica nanoparticles is known to have a strong effect on the properties of hardened cement paste, as well as the rheology and hydration process of the fresh paste. In the present work the hydration process of cement pastes containing SiO2 nanoparticles, both silanized and unmodified, was monitored. Two complementary techniques, the low-field...