Hydration and Dehydration of High Initial Strength Portland Cement Type CP V - ARI

2016 ◽  
Vol 869 ◽  
pp. 106-111
Author(s):  
Aloízio Geraldo de Araújo Jr. ◽  
Leandro José da Silva ◽  
Túlio Hallak Panzera ◽  
Adriano Galvão da Souza Azevedo ◽  
Kurt Strecker
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Elevated Temperatures ◽  
Morphological Changes ◽  
Heat Treating ◽  
Gravimetric Analysis ◽  
Hydrated Cement ◽  
Cement Pastes ◽  
Initial Strength ◽  
Hydration And Dehydration

It is known that the hydration of cement paste is influenced by a variety of factors, it is also known that some hydration products are gradually dehydrated at elevated temperatures. In doing so, different author studied the dehydration of hydrated cement pastes under different condition. In this work, samples of Hydrated Cement Paste (HCP) were prepared from Portland cement of high initial strength (CP V-ARI) with a water/cement ratio of 0.5. The morphological changes during hydration and dehydration by subsequent heat-treatments were analyzed by X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). Thermal Gravimetric Analysis (TGA) was used to study the thermal stability of the HCP. Dehydrated cement powder samples (DCP) were obtained heat treating samples of HCP at 300, 500, 700 and 900°C. After 7 days of curing HCP samples exhibited no significant changes in its structure. HCP dehydrated at 500°C showed the absence of Ca (OH)2 and calcium silicate hydrate. At 700°C the formation of β-2CaO.SiO2, 3CaO.SiO2 and CaO is observed. During heat treatment at 900°C the HCP revealed a significant mass loss of 36%.

Early carbonation curing effects on the microstructure of high initial strength Portland cement pastes

2019 ◽  
Vol 31 (8) ◽  
pp. 382-388 ◽  
Author(s):  
Alex Neves Junior ◽  
Romildo Dias Toledo Filho ◽  
Jo Dweck ◽  
Frank K. Cartledged ◽  
Eduardo de Moraes Rego Fairbairn
Keyword(s):  
Portland Cement ◽  
Cement Pastes ◽  
Initial Strength ◽  
Carbonation Curing

Interaction Between Naphthalene Sulfonate and Silica Fume in Portland Cement Pastes

1987 ◽  
Vol 114 ◽  
Author(s):  
Sidney Diamond ◽  
Leslie J. Struble
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
Cement Paste ◽  
Uv Spectrophotometry ◽  
Residual Concentration ◽  
Cement Pastes ◽  
High Ph ◽  
Substantial Concentration ◽  
Low Dosage

ABSTRACTPortland cement pastes were mixed with predissolved naphthalene sulfonate superplasticizer at normal water:cement ratios. Solutions were separated from the fresh pastes at intervals and the residual concentration of the superplasticizer determined by UV spectrophotometry. At low dosage levels essentially all of the superplasticizer was found to be removed from solution within a few minutes; at high dosage levels a substantial concentration was maintained in solution at least to approximately the time of set. In pastes in which silica fume replaced 10% by weight of the cement, it was found that the incorporation of silica fume significantly increased the uptake of superplasticizer. In separate trials it was found that the silica fume by itself adsorbed little superplasticizer, even from high pH solution simulating that of cement paste.

Mathematical modeling of cement paste microstructure by mosaic pattern. Part II. Application

1997 ◽  
Vol 12 (7) ◽  
pp. 1741-1746 ◽  
Author(s):  
Paul D. Tennis ◽  
Yunping Xi ◽  
Hamlin M. Jennings
Keyword(s):  
Mathematical Modeling ◽  
Spatial Distribution ◽  
Portland Cement ◽  
Cement Paste ◽  
Pattern Analysis ◽  
Mosaic Pattern ◽  
Cement Pastes ◽  
Multiphase Materials ◽  
Spatial Features ◽  
Complex Shapes

A model based on mosaic pattern analysis is shown to have the potential to describe the complex shapes and spatial distribution of phases in the microstructures of multiphase materials. Several characteristics of both micrographs of portland cement pastes and images generated using the few parameters of the model are determined and, for the most part, agreement is good. The advantage is that spatial features of the microstructures can be captured by a few parameters.

Estimation and Measurement of Porosity Change in Cement Paste

2010 ◽  
Author(s):  
Eunyong Lee ◽  
Haeryong Jung ◽  
Ki-jung Kwon ◽  
Do-Gyeum Kim
Keyword(s):  
Ionic Strength ◽  
Portland Cement ◽  
Cement Paste ◽  
Thermodynamic Model ◽  
Ordinary Portland Cement ◽  
Type I ◽  
Hydration Products ◽  
Cement Pastes ◽  
Porosity Change ◽  
Dissolution Reaction

Laboratory-scale experiments were performed to understand the porosity change of cement pastes. The cement pastes were prepared using commercially available Type-I ordinary Portland cement (OPC). As the cement pastes were exposed in water, the porosity of the cement pastes sharply increased; however, the slow decrease of porosity was observed as the dissolution period was extended more than 50 days. As expected, the dissolution reaction was significantly influenced by w/c raito and the ionic strength of solution. A thermodynamic model was applied to simulate the porosity change of the cement pastes. It was highly influenced by the depth of the cement pastes. There was porosity increase on the surface of the cement pastes due to dissolution of hydration products, such as portlandite, ettringite, and CSH. However, the decrease of porosity was estimated inside the cement pastes due to the precipitation of cement minerals.

Rectifying and thermocouple junctions based on Portland cement

2001 ◽  
Vol 16 (7) ◽  
pp. 1989-1993 ◽  
Author(s):  
Sihai Wen ◽  
D. D. L. Chung
Keyword(s):  
Carbon Fiber ◽  
Portland Cement ◽  
Cement Paste ◽  
Steel Fiber ◽  
Cement Pastes

Rectifying and thermocouple junctions have been achieved using electrically dissimilar Portland cement pastes. The preferred junction is a pn-junction involving steel fiber cement paste (n-type) and carbon fiber cement paste (p-type). For this junction, the thermocouple sensitivity is 70 εV/°C.

The effects of the early carbonation curing on the mechanical and porosity properties of high initial strength Portland cement pastes

2015 ◽  
Vol 77 ◽  
pp. 448-454 ◽  
Author(s):  
Alex Neves Junior ◽  
Romildo Dias Toledo Filho ◽  
Eduardo de Moraes Rego Fairbairn ◽  
Jo Dweck
Keyword(s):  
Portland Cement ◽  
Cement Pastes ◽  
Initial Strength ◽  
Carbonation Curing

Small-Angle Neutron Scattering from Hydrated Cement Pastes

1994 ◽  
Vol 376 ◽  
Author(s):  
L.P. Aldridge ◽  
W.K. Bertram ◽  
T.M. Sabine ◽  
J Bukowski ◽  
J.F. Young ◽  
...  
Keyword(s):  
Data Analysis ◽  
Neutron Scattering ◽  
Cement Paste ◽  
Small Angle ◽  
Calcium Silicate ◽  
Small Angle Neutron Scattering ◽  
Calcium Silicate Hydrate ◽  
Hydrated Cement ◽  
Cement Pastes ◽  
Hydrated Cement Paste

ABSTRACTSmall angle neutron scattering (SANS) has been used to examine hydrated cement pastes with water-to-cement ratios between 0.25 and 0.8 and cured for 28 days. Various methods of data analysis are applied to the pastes.Fitting the entire SANS spectra of the hydrated cement paste has suggested that there are two scattering entities in the paste. There is some evidence to suggest that one scattering entity is globules of calcium silicate hydrate formed in the hydrated paste.

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