Hydration and microstructural development of calcined clay cement paste in the presence of calcium-silicate-hydrate (C–S–H) seed

2021 ◽  
pp. 104162
Author(s):  
Diandian Zhao ◽  
Rahil Khoshnazar
Keyword(s):  
Cement Paste ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Microstructural Development ◽  
Calcined Clay

scholarly journals Effect of water/cement ratio on micro-nanomechanical properties of the interface between cementitious matrix and steel microfibers in ultra-high performance cementitious composites

2021 ◽  
Vol 14 (4) ◽  
Author(s):  
Vanessa Fernandes Cesari ◽  
Fernando Pelisser ◽  
Philippe Jean Paul Gleize ◽  
Milton Domingos Michel
Keyword(s):  
Transition Zone ◽  
Cement Paste ◽  
Calcium Silicate ◽  
High Performance ◽  
Calcium Silicate Hydrate ◽  
Interfacial Transition Zone ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Nanomechanical Properties ◽  
Cementitious Matrix

abstract: Ultra-high performance concretes with steel microfibers have been studied in depth with the aim of producing more efficient and durable structures. The performance of these materials depends on the characteristics of the interface between microfibers and cementitious matrix. This research investigates the micro-nanomechanical properties of the interfacial transition zone between the steel microfibers and the matrix of ultra-high performance cementitious composite. The effect of the water/cement ratio and distance from the microfiber were analyzed. The results confirm the formation of high-density calcium-silicate-hydrate (HD C-S-H) matrix at higher concentrations than low-density calcium-silicate-hydrate (LD C-S-H) for w/c ratios of 0.2 and 0.3. The properties in cementitious matrix interface with steel microfibers were very similar to that measured for the cement paste, and no significant difference was observed regarding the distance to the microfibers in relation to the elastic modulus, hardness and chemical composition. Thus, the authors can conclude that the formation of a less resistant region does not occur at the interfacial transition zone cement paste/microfibers.

Nanoscale investigation of the influence of water on the elastic properties of C–S–H gel by molecular simulation

2017 ◽  
Vol 233 (7) ◽  
pp. 1295-1306 ◽  
Author(s):  
Davoud Tavakoli ◽  
Amir Tarighat ◽  
Javad Beheshtian
Keyword(s):  
Molecular Dynamics ◽  
Young’S Modulus ◽  
Cement Paste ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Young's Modulus ◽  
Molecular Structures ◽  
Dynamics Simulation ◽  
Effect Of Water ◽  
The Impact

Calcium silicate hydrate (C–S–H) gel contains almost 50% to 70% of cement paste, which has a significant effect on the cement paste properties. An attempt is made to assess the atomistic structure of calcium silicate hydrate and the impact of water on it through molecular dynamics simulation. The most similar compositions (tobermorite 14Å, tobermorite 11Å, and jennite) are chosen and the effect of water thereof is studied. This study is presented in two phases: (1) water removal from the structure and simulating difference of water-to-calcium ratios through grand canonical Monte Carlo method. Next, the effect of water on the mechanical properties of C–S–H gel is examined through molecular dynamics method. (2) Defects in the existing molecular structures were introduced, which lead to newer Ca–Si proportions followed by the examination of the effect of water on the new structures. The obtained results revealed that as W/Ca ratio increases, the Young's modulus decreases. An increase in the Ca/Si ratio, owing to the defects in the structure, leads to the reduction in the Young's modulus.

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.

scholarly journals Characterization of Early Pozzolanic Reaction of Calcium Hydroxide and Calcium Silicate Hydrate for Nanosilica Modified Cement Paste

2013 ◽  
Vol 4 (3) ◽  
pp. 6-10
Author(s):  
J.Z. Chong ◽  
N.M. Sutan ◽  
I. Yakub
Keyword(s):  
Calcium Hydroxide ◽  
Cement Paste ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Pozzolanic Reaction ◽  
Pozzolanic Reactivity ◽  
Characterization Technique ◽  
Binder Ratio ◽  
Ft Ir

This  study  intends  to  investigate  the  early   pozzolanic  reaction  of  Nanosilica (nS)         modified cement paste (NMCP)  by  the characterization technique  of Calcium Hydroxide (CH) and Calcium Silicate Hydrate (C-S-H ) using Fourier Transform Infrared Spectroscopy (FT-IR). NMCP samples were prepared with water-binder ratio of 0.50. nS of 5-15nm particle size were used as 1%, 3% ,5% ,7% and 10% replacement of cement by weight. All samples were cured in the concrete laboratory at daily room temperature (T) and relative humidity (RH) in the range of 18-28oC and 65-90%, respectively. Powdered samples were prepared and tested at day 1,7,21 and 28. It was found that characterization technique used were able to give satisfactory qualitative indication of pozzolanic reactivity of NMCP by the presence and absence of C-S-H and C-H that can indicate which replacement has higher pozzolanicity. NMCP exhibited a higher pozzolanic reactivity compare to conventional cement paste by which cement performance was enhanced.

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