Specific Gravities and Electrical Conductances of Some Calcium Sulfate Solutions and Mixtures of Sodium Chloride and Calcium Sulfate

1941 ◽  
Vol 63 (5) ◽  
pp. 1418-1422 ◽  
Author(s):  
Randall E. Hamm ◽  
Thomas G. Thompson
Keyword(s):  
Sodium Chloride ◽  
Calcium Sulfate ◽  
Electrical Conductances ◽  
Sulfate Solutions

Thermal Behavior of the Gypsum Binder in Dental Casting Investments

1986 ◽  
Vol 65 (6) ◽  
pp. 877-884 ◽  
Author(s):  
T. Mori
Keyword(s):  
Phase Transition ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Sodium Chloride ◽  
Thermal Behavior ◽  
Boric Acid ◽  
Atmospheric Pressure ◽  
Calcium Sulfate ◽  
Calcium Sulfate Dihydrate ◽  
Initial Stage

This study examined the thermal behavior of cast gypsum specimens, with and without additives, by means of simultaneous differential thermal analysis-thermogravimetry (DTA-TG) and dilatometry. Specimens were prepared from wet-calcined hemihydrates (Hydrocal and Den-site). The additives studied were boric acid (H3BO 3) and sodium chloride (NaCl), and these were added to the hemihydrate powders in concentrations of 2 wt% (in the case of H3BO3) and 0.5 wt% (in the case of NaCl). A large shrinkage was observed in the range of 300 to 500°C, and this was greatly reduced when either H3BO3 or NaCl was present. The dehydration of gypsum (calcium sulfate dihydrate) was not completed until the initial stage of this large shrinkage was reached, but the phase transition of calcium sulfate anhydrite (III-CaSO4 to II-CaSO4) was the major cause for the large shrinkage. This phase transition occurred over a much wider temperature range than that suggested by the DTA-TG results. Dehydration conditions similar to those employed in wet calcination of gypsum appeared to be produced under atmospheric pressure when NaCl was present.

scholarly journals SODIUM CHLORIDE (SALT) ITS ROLE AND USE IN ANCIENT IRAQ

2021 ◽  
Vol 03 (06) ◽  
pp. 451-457
Author(s):  
Shaymaa Issam Alawi ALBALDAWI ◽  
Faten Hameed Qasim AL SARRAJI
Keyword(s):  
Sodium Chloride ◽  
Sodium Silicate ◽  
Sodium Carbonate ◽  
Calcium Sulfate ◽  
Potassium Nitrate ◽  
Chemical Technology ◽  
Chloride Salt ◽  
Table Salt ◽  
Mineral Salts ◽  
Ancient Mesopotamia

Mineral Salts are One of the Most important Non-Metallic Chemicals that were widely available in ancient Iraq, and due to its many Uses in life Matters and for industrial purposes, it was Allocated in the Study of a Type of these Salts, which is Sodium Chloride salt (Table Salt), as there were Several Types, including: - Calcium Sulfate Sodium Silicate, Sodium Carbonate and Potassium Nitrate Because of the Importance of Sodium Chloride (salt) in Ancient Iraq and the lack of Studies that Dealt with it, we Chose it as a Subject for our Study, and we Relied on Many Arab, Translated and Foreign Sources, the most important of which are: -Levy, Martin, 1980 , Chemistry and Chemical Technology, translated by: Al-Mayahi and others, Dar Al-Rashid. - Potts ,D.,1987,'' ON Salt and salting gathering in Ancient Mesopotamia ''(JESHO), vol.27‎.

scholarly journals Estimators of the Impact of Climate Change in Salt Weathering of Cultural Heritage

Geosciences ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 401 ◽  
Author(s):  
Beatriz Menéndez
Keyword(s):  
Climate Change ◽  
Sodium Chloride ◽  
Cultural Heritage ◽  
Sodium Sulfate ◽  
Calcium Sulfate ◽  
Phase Changes ◽  
Salt Weathering ◽  
Sodium Calcium ◽  
Calcium Magnesium ◽  
The Impact

Changes induced by climate change in salt weathering of built cultural heritage are estimated in different ways, but generally as a function of phase changes phenomena of two common salts, sodium chloride and sodium sulfate. We propose to use not only these salts, but also other common salts as calcium sulfate, or mixtures of chlorides, sulfates, and nitrates of sodium, calcium, magnesium, and potassium. Comparisons between the predicted changes in salt weathering obtained for single salts and for combinations of different salts are presented. We applied the proposed methodology to 41 locations uniformly distributed in France. The results show that estimations of actual and evolution of future weathering depend on the selected salt or combination of salts. According to our results, when using a combination of different salts, weathering evolution is less favorable (more damage in the future) than when using a single salt.

Sign in / Sign up

Export Citation Format

Share Document