NON-DESTRUCTIVE EXPERIMENTS AND MODELING OF CALCIUM CARBONATE FORMATION IN SOILS

Efflorescence phenomenon on concrete is not new and found in the form of white deposits on surfaces of concrete. Incorporation of Finely Ground Mineral Admixture (FGMA) in concrete to prevent occurrence of efflorescence is based on reduction of portlandite, densified microstructure and thus enhanced watertightness. The magnitude of efflorescence in term of percentage of calcium carbonate formation of FGMA modified mortar were evaluated at water-cement ratio of 0.3, 0.4 and 0.5 with 10%, 20%, and 30% of cement replacement by weight. The samples were tested with chemical analysis at 7, 14, 21, 28, 60 and 90 days. The FGMA additions into mortar were comparing with ordinary mortar to evaluate enhanced performance of FGMA modified mortar toward efflorescence. The results of this experiment showed that addition of FGMA into mortar caused less formation of calcium carbonate as partial replacement of cement with certain w/c ratio and percentage of cement replacement.

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Structural characterization of amorphous calcium carbonate-binding protein: an insight into the mechanism of amorphous calcium carbonate formation

Biochemical Journal ◽

10.1042/bj20130285 ◽

2013 ◽

Vol 453 (2) ◽

pp. 179-186 ◽

Cited By ~ 14

Author(s):

Jingtan Su ◽

Xiao Liang ◽

Qiang Zhou ◽

Guiyou Zhang ◽

Hongzhong Wang ◽

...

Keyword(s):

Calcium Carbonate ◽

Binding Sites ◽

Binding Protein ◽

Homology Modelling ◽

Size Exclusion ◽

Structural Basis ◽

Amorphous Calcium Carbonate ◽

Carbonate Formation

ACC (amorphous calcium carbonate) plays an important role in biomineralization process for its function as a precursor for calcium carbonate biominerals. However, it is unclear how biomacromolecules regulate the formation of ACC precursor in vivo. In the present study, we used biochemical experiments coupled with bioinformatics approaches to explore the mechanisms of ACC formation controlled by ACCBP (ACC-binding protein). Size-exclusion chromatography, chemical cross-linking experiments and negative staining electron microscopy reveal that ACCBP is a decamer composed of two adjacent pentamers. Sequence analyses and fluorescence quenching results indicate that ACCBP contains two Ca2+-binding sites. The results of in vitro crystallization experiments suggest that one Ca2+-binding site is critical for ACC formation and the other site affects the ACC induction efficiency. Homology modelling demonstrates that the Ca2+-binding sites of pentameric ACCBP are arranged in a 5-fold symmetry, which is the structural basis for ACC formation. To the best of our knowledge, this is the first report on the structural basis for protein-induced ACC formation and it will significantly improve our understanding of the amorphous precursor pathway.

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Non-Destructive Analysis of 14th–19th Century European Handmade Papers

Restaurator International Journal for the Preservation of Library and Archival Material ◽

10.1515/res-2015-0017 ◽

2016 ◽

Vol 37 (2) ◽

Cited By ~ 4

Author(s):

Timothy Barrett ◽

Mark Ormsby ◽

Joseph B. Lang

Keyword(s):

Calcium Carbonate ◽

19Th Century ◽

Calcium Concentration ◽

Natural Ageing ◽

Destructive Analysis ◽

Non Destructive ◽

Over Time

AbstractNon-destructive analysis of 1,578 paper specimens made between the fourteenth and the nineteenth centuries was undertaken in an effort to better understand changes in paper composition over time and how these variations might affect paper stability during long term natural ageing. Gelatine content and colour were determined using UV/Vis/NIR spectrometry. Residual metals were measured using XRF. These components included potassium and sulfur as elements indicative of alum concentration; iron as a typical paper contaminant; and calcium, which is often associated with compounds such as calcium carbonate that can serve as alkaline reserves. The research demonstrated that papers that are lighter in colour (closer to white) are associated with higher levels of gelatine and calcium, and lower levels of iron. The survey also showed significant decreases in gelatine and calcium concentration over time with the largest differences coinciding with the rise of printing around 1500. The drop in pH over the centuries observed by other researchers is explained by the decreases in these two components rather than by a rise in alum concentration, which remained fairly stable. The craftsmanship of the specimens was evaluated using materials and workmanship ratings which showed better quality paper associated with higher gelatine and calcium concentrations and colour closer to white. Poorer quality papers were associated with higher iron levels and greater thickness.

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