What happens when calcium silicates hydrate?
Calcium silicate hydrate (also shown as C-S-H) is a result of the reaction between the silicate phases of Portland cement and water. This reaction typically is expressed as: 2 Ca 3SiO 5 + 7 H 2O → 3 CaO · 2 SiO 2 · 4 H 2O + 3 Ca(OH) 2 + 173.6 kJ.
Can FTIR detect calcium?
You can’t detect the Calcium band through FTIR. The OH- bands should be around 1600-1700 cm-1 and 3500-3700cm-1. While Phosphate bands normally at 550-570, 960-966 cm-1.
Where is FTIR water peak?
As is well known form FTIR spectra of water, there are three “peaks” in the spectra for water structure study (Max et al., 2007). The “peak” at 3200 cm− 1 corresponds to the complete hydrogen bonding between water molecules in tetrahedral coordination (the “ice-like” water structure).
What are peaks in FTIR?
The peaks, which are also called absorbance bands, correspond with the various vibrations of the sample’s atoms when it’s exposed to the infrared region of the electromagnetic spectrum. For mid-range IR, the wave number on the infrared spectrum is plotted between 4,000 to 400 cm-1.
Why is calcium silicate hydrate C-S-H called a gel?
1.1 Calcium Silicate Hydrate. Calcium silicate hydrate is produced by reaction of C3S or C2S with water. It is frequently described as a gel rather than a crystalline material because no consistent structure is discernible using X-ray diffraction.
What do you mean by C-S-H gel found during hydration process?
Calcium-silicate-hydrate
Calcium-silicate-hydrate(C-S-H) gel is a primary nano-crystalline phase present in hydrated Ordinary Portland Cement (OPC) responsible for its strength and creep behavior. Our reliance on cement for infrastructure is global, and there is a need to improve infrastructure life-times.
What are the physical properties of calcium carbonate?
Calcium carbonate is an odorless, fine white powder. It has a density of 2.71 g/mL ,and a melting point of 1,339°C in its calcite form. Calcium carbonate is insoluble in water and stable at normal temperatures. When heated to high temperatures, it decomposes to form calcium oxide with the release of carbon dioxide.
Where does water appear in IR?
Water has an IR spectrum with strong peaks in areas where we don’t want to see it. All alcohols, amines, and carboxylic acids, among other similar functional groups, have peaks in the 3500~3000cm−1 range. Using water would defeat the purpose of identifying those types of compounds.
What is the IR spectrum of water?
In the near-infrared range liquid water has absorption bands around 1950 nm (5128 cm−1), 1450 nm (6896 cm−1), 1200 nm (8333 cm−1) and 970 nm, (10300 cm−1).
What does a broad peak mean in IR?
A very broad peak in the region between 3100 and 3600 cm-1 indicates the presence of exchangeable protons, typically from alcohol, amine, amide or carboxylic acid groups (see further discussion of this below).
Why is the OH peak broad?
The H-bonding would cause there to be a lot of variance in the strength of the O-H bond of the and because the wavelength that is absorbed is partially dependent on the strength of the bond, this would cause there to a broad amount of wavelengths absorbed, thus the broad peak around 3500.
What are calcium silicate hydrates?
Calcium silicate hydrates are nanocrystalline porous materials of variable composition and poor crystallinity analogous to the compounds occurring in hydrated cements.
What is the molecular formula for calcium silicate?
Molecular Formula. CaH2O4Si. Synonyms. CALCIUM SILICATE HYDRATE. 1344-96-3. 14404-64-9. Ca.SO3i.H2O. DTXSID40932194.
What is the difference between C2S hydration and C3S hydrates?
However, in general the ratio of CaO to SiO 2 is close to that of C 2 S from the cement clinker and as a result C 2 S hydration produces predominantly C-S-H. However, when C 3 S hydrates there is excess CaO available so as well as forming C-S-H the extra CaO reacts with water to produce calcium hydroxide. A. Gmira,