Impedance Spectroscopy and the Role of Admixtures in the Hydration of Portland Cement Pastes

1991 ◽  
Vol 245 ◽  
Author(s):  
Bruce J. Christensen ◽  
Thomas O. Mason ◽  
Hamlin M. Jennings
Keyword(s):  
Electrical Properties ◽  
Impedance Spectroscopy ◽  
Portland Cement ◽  
Silica Fume ◽  
Pore Fluid ◽  
Microstructural Development ◽  
Portland Cements ◽  
Cement Pastes ◽  
Degree Of Hydration

ABSTRACTMeasurements of the bulk electrical properties of cement pastes were made using impedance spectroscopy (IS) and are useful for studying hydration. Normalization of these quantities by dividing out changes in the pore fluid reveals information pertinent to the microstructural development of these materials. In this study, observations are made on the influence of accelerators, retarders and silica fume (SF) on pastes of white and ordinary portland cements (OPC). All systems show variations in the normalized electrical properties at the same degree of hydration, as compared to a control. Changes in the microstructure that are implied by these measurements are consistent with the observations of others.

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.

Microstructure of Cement Blends Including Fly Ash, Silica Fume, Slag and Fillers

1986 ◽  
Vol 86 ◽  
Author(s):  
Micheline Regourd
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Silica Fume ◽  
Blended Cement ◽  
Cement Clinker ◽  
Microstructural Development ◽  
Limestone Filler ◽  
Portland Cement Clinker

ABSTRACTThe hydration of a blended cement through hydraulic or pozzolanic reactions results in heterogeneous polyphase materials. Because portland cement clinker is the major component in most cement blends, the microstructural development of portland cement hydrates, including C-S-H and pore structures, is first discussed. Slag, fly ash, silica fume and limestone filler cements are then compared to portland cement with regards to C-S-H morphology and composition, aluminate crystallization, cement paste interfaces and pore size distribution.

Effect of Heat Treatment on Properties of Portland Cement Pastes: Determination through Ultra-Microhardness Test

2015 ◽  
Vol 820 ◽  
pp. 492-496
Author(s):  
D.C.S. Garcia ◽  
Roberto Braga Figueiredo ◽  
Maria Teresa Paulino Aguilar
Keyword(s):  
Heat Treatment ◽  
Portland Cement ◽  
Optical Microscopy ◽  
Silica Fume ◽  
Ordinary Portland Cement ◽  
Cement Pastes ◽  
Microhardness Test ◽  
Material Hardness ◽  
Binder Ratio ◽  
Water Binder Ratio

The aim of this paper was to investigate the influence of heat treatment on hardness evolution of cement pastes containing silica fume. The specimens were prepared with Ordinary Portland Cement, water/binder ratio of 0,40 and 25% wt. silica fume. The specimens were cast at room temperatures and after 24 hours, they were placed in a furnace for 24 hours, with heat regimes of 100°C, 200°C and 300°C and then submitted to the ultra-microhardness test. The microstructure was analyzed using optical microscopy. The results showed that the silica fume prevents the production of calcium hydroxide and the heat treatment increases the material hardness.

Estimations of degree of hydration of portland cement pastes

1993 ◽  
Vol 23 (2) ◽  
pp. 399-406 ◽  
Author(s):  
J.E. Ash ◽  
M.G. Hall ◽  
J.I. Langford ◽  
M. Mellas
Keyword(s):  
Portland Cement ◽  
Cement Pastes ◽  
Degree Of Hydration

The role of metakaolin in pore structure evolution of Portland cement pastes revealed by an impedance approach

2021 ◽  
Vol 119 ◽  
pp. 103999
Author(s):  
Rongjin Cai ◽  
Zushi Tian ◽  
Hailong Ye ◽  
Zhen He ◽  
Shengwen Tang
Keyword(s):  
Portland Cement ◽  
Pore Structure ◽  
Structure Evolution ◽  
Cement Pastes

Small-angle scattering studies of the pore structure of polymer-modified portland cement pastes

1990 ◽  
Vol 5 (6) ◽  
pp. 1281-1284 ◽  
Author(s):  
V. M. Castaño ◽  
P. W. Schmidt ◽  
H. G. Hörnis
Keyword(s):  
Portland Cement ◽  
Neutron Scattering ◽  
Pore Structure ◽  
Small Angle ◽  
Small Angle Scattering ◽  
Cement Pastes ◽  
X Ray ◽  
Angle Scattering ◽  
Gel Porosity

Small-angle x-ray and neutron scattering experiments were performed in several polymer-containing portland cement pastes with the same w/c ratio. The nature of the results is discussed in terms of the role of the polymer upon the properties of the materials. A comparison with other works seems to indicate that the capillary pores are strongly affected whereas the gel porosity remains unchanged by the polymer solutions.

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