CO2 Treatment of Hydrated Cement Powder: Characterization and Application Consideration

2021 ◽  
Vol 33 (4) ◽  
pp. 04021041
Author(s):  
Hamideh Mehdizadeh ◽  
Tung-Chai Ling ◽  
Xiongfei Cheng ◽  
Shu-Yuan Pan ◽  
Kim Hung Mo
Keyword(s):  
Hydrated Cement ◽  
Cement Powder ◽  
Powder Characterization ◽  
Co2 Treatment

scholarly journals Effects of Sugar and Hydrated Cement Powder on the Reduction in Heat of Hydration

2014 ◽  
Vol 14 (2) ◽  
pp. 135-142 ◽  
Author(s):  
Hoon Moon ◽  
Ji-Hyun Kim ◽  
Yong-Hun Cho ◽  
Jae-Yong Lee ◽  
Chul-Woo Chung
Keyword(s):  
Heat Of Hydration ◽  
Hydrated Cement ◽  
Cement Powder

Effect of particle size and CO2 treatment of waste cement powder on properties of cement paste

2020 ◽  
Author(s):  
Hamideh Mehdizadeh ◽  
Tung-Chai Ling ◽  
Xiongfei Cheng ◽  
Kim Hung Mo
Keyword(s):  
Particle Size ◽  
Cement Paste ◽  
Blended Cement ◽  
Hydration Products ◽  
Cement Powder ◽  
Effect Of Particle Size ◽  
The Impact ◽  
Blended Cement Paste ◽  
Co2 Treatment

This paper studies the role of CO2 treatment and the impact of particle size (<75 μm and 75-150 μm) of waste cement powder (WCP) with different cement replacement content (0%, 5%, 10%, 15%, 20%, and 30%) on the physical properties and microstructure of blended cement paste. The results show that carbonation of WCP can effectively increase the flowability of paste due to the formation of calcite and decrease the porosity of WCP microstructure, while the water demand to achieve the same workability decreases with increasing size of WCP particles. Cement paste containing decreased particles of carbonated waste cement powder (CWCP) possesses a higher 28-day compressive strength due to formation of a higher amount of calcite and hydration products, based on the thermogravimetric analysis.

Elucidation of block boundaries as the dissolution channels in hydrated cement

1978 ◽  
Vol 36 (1) ◽  
pp. 484-485
Author(s):  
N.V. Belov ◽  
U.I. Papiashwili ◽  
B.E. Yudovich
Keyword(s):  
Liquid Phase ◽  
Grain Boundaries ◽  
Benzoyl Peroxide ◽  
Phase Contrast ◽  
Active Role ◽  
Point Of View ◽  
Hardened Cement ◽  
Hydrated Cement ◽  
Hardened Cement Paste

It has been almost universally adopted that dissolution of solids proceeds with development of uniform, continuous frontiers of reaction.However this point of view is doubtful / 1 /. E.g. we have proved the active role of the block (grain) boundaries in the main phases of cement, these boundaries being the areas of hydrate phases' nucleation / 2 /. It has brought to the supposition that the dissolution frontier of cement particles in water is discrete. It seems also probable that the dissolution proceeds through the channels, which serve both for the liquid phase movement and for the drainage of the incongruant solution products. These channels can be appeared along the block boundaries.In order to demonsrate it, we have offered the method of phase-contrast impregnation of the hardened cement paste with the solution of methyl metacrylahe and benzoyl peroxide. The viscosity of this solution is equal to that of water.

Study Of Structure Formation Of Organic-Mineral Compositions With Fibrous Filler By Electron Microscopy Method

2019 ◽  
pp. 41-47
Keyword(s):  
Electron Microscopy ◽  
Structure Formation ◽  
Mineral Composition ◽  
Bending Strength ◽  
Cement Stone ◽  
Hydrated Cement ◽  
Fibrous Filler ◽  
Organic Mineral ◽  
Microscopy Method ◽  
Mineral Compositions

The article presents the study of processes of structure formation of cement stone and products of hardening of organic-mineral compositions with fibrous filler (shavings) by the electronic scanning microscopy method. It is established that the additive-free cement stone at the age of 28 days has a dense and homogeneous structure, consists of calcium hydro-silicates, Portlandite and calcite - newgrowths characteristic for cement systems. Cellulose fibers, which make up the bulk of the substance of shavings, are sufficiently active, which determines the high adhesion of the hydration products of the cement binder to their surface. It is shown that the introduction of shavings into the organo-mineral composition leads to inhibition of cement hydration processes. Organo-mineral compositions with different shavings content (two compositions) were analyzed. The first composition is characterized by a fairly dense structure, the cement stone consists of globular nanoscale nuclei of hydrosilicates, Portlandite and calcite. The second composition has a loose porous structure, cement stone consists of non-hydrated cement grains, newgrowths are represented by calcite and vaterite. The structure of the contact zone "osprey fiber-cement stone" in the organo-mineral composition of the first composition indicates a good adhesion of the filler surface with the phases of hydrated cement. The use of shavings as a fibrous filler (the first composition) increases the tensile and bending strength, as well as the wear resistance of organo-mineral compositions. The data obtained by scanning electron microscopy are confirmed by the results of studying the processes of structure formation of cement stone by quantitative x-ray phase analysis.

Enhanced Electrical Characteristics of Ge nMOSFET by Supercritical Fluid CO2 Treatment with H2O2 Cosolvent

2021 ◽  
pp. 1-1
Author(s):  
Dun-Bao Ruan ◽  
Kuei-Shu Chang-Liao ◽  
Guan-Ting Liu ◽  
Yu-Chuan Chiu ◽  
Kai-Jhih Gan ◽  
...  
Keyword(s):  
Supercritical Fluid ◽  
Electrical Characteristics ◽  
Supercritical Fluid Co2 ◽  
Co2 Treatment

scholarly journals Inhaled H2 or CO2 Do Not Augment the Neuroprotective Effect of Therapeutic Hypothermia in a Severe Neonatal Hypoxic-Ischemic Encephalopathy Piglet Model

2020 ◽  
Vol 21 (18) ◽  
pp. 6801
Author(s):  
Viktória Kovács ◽  
Gábor Remzső ◽  
Valéria Tóth-Szűki ◽  
Viktória Varga ◽  
János Németh ◽  
...  
Keyword(s):  
Caudate Nucleus ◽  
Therapeutic Hypothermia ◽  
Neuroprotective Effect ◽  
Fold Increase ◽  
Hypoxic Ischemic Encephalopathy ◽  
Mrna Levels ◽  
Treatment Groups ◽  
Apoptosis Inducing Factor ◽  
Co2 Treatment ◽  
Ischemic Encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is still a major cause of neonatal death and disability as therapeutic hypothermia (TH) alone cannot afford sufficient neuroprotection. The present study investigated whether ventilation with molecular hydrogen (2.1% H2) or graded restoration of normocapnia with CO2 for 4 h after asphyxia would augment the neuroprotective effect of TH in a subacute (48 h) HIE piglet model. Piglets were randomized to untreated naïve, control-normothermia, asphyxia-normothermia (20-min 4%O2–20%CO2 ventilation; Tcore = 38.5 °C), asphyxia-hypothermia (A-HT, Tcore = 33.5 °C, 2–36 h post-asphyxia), A-HT + H2, or A-HT + CO2 treatment groups. Asphyxia elicited severe hypoxia (pO2 = 19 ± 5 mmHg) and mixed acidosis (pH = 6.79 ± 0.10). HIE development was confirmed by altered cerebral electrical activity and neuropathology. TH was significantly neuroprotective in the caudate nucleus but demonstrated virtually no such effect in the hippocampus. The mRNA levels of apoptosis-inducing factor and caspase-3 showed a ~10-fold increase in the A-HT group compared to naïve animals in the hippocampus but not in the caudate nucleus coinciding with the region-specific neuroprotective effect of TH. H2 or CO2 did not augment TH-induced neuroprotection in any brain areas; rather, CO2 even abolished the neuroprotective effect of TH in the caudate nucleus. In conclusion, the present findings do not support the use of these medical gases to supplement TH in HIE management.

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