The Quantitative Calculation the Volume Fraction of Cement Pastes

2010 ◽  
Vol 168-170 ◽  
pp. 156-160
Author(s):  
Zhi Yong Liu ◽  
Yun Sheng Zhang ◽  
Guo Wen Sun
Keyword(s):  
Volume Fraction ◽  
Cement Pastes ◽  
Volume Percentage ◽  
Cement Ratio ◽  
Degree Of Hydration ◽  
Quantitative Calculation ◽  
Water To Cement Ratio ◽  
Saturated Density ◽  
Experimental Values ◽  
Creep And Shrinkage

The knowledge of the microstructure is a point of major importance to understand the transport, mechanics, creep and shrinkage properties. The present work proposes a method to quantitatively predict the volume percentage of each of phases in Portland cement pastes. The saturated density of C-S-H is revised as a function of degree of hydration and water to cement ratio (w/c). The computed results are consistent with experimental values for cement paste that performed in this study.

scholarly journals Surface Roughness and Porosity of Hydrated Cement Pastes

10.14311/1374 ◽  
2011 ◽  
Vol 51 (3) ◽  
Author(s):  
T. Ficker ◽  
D. Martišek ◽  
H. M. Jennings
Keyword(s):  
The Other ◽  
Porous Solids ◽  
Surface Irregularity ◽  
Hydrated Cement ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Fracture Surfaces ◽  
Water To Cement Ratio ◽  
The One ◽  
Highly Porous

. Seventy-eight graphs were plotted to describe and analyze the dependences of the height and roughness irregularities on the water-to-cement ratio and on the porosity of the cement hydrates. The results showed unambiguously that the water-to-cement ratio or equivalently the porosity of the specimens has a decisive influence on the irregularities of the fracture surfaces of this material. The experimental results indicated the possibility that the porosity or the value of the water-to-cement ratio might be inferred from the height irregularities of the fracture surfaces. It was hypothesized that there may be a similarly strong correlation between porosity and surface irregularity, on the one hand, and some other highly porous solids, on the other, and thus the same possibility to infer porosity from the surfaces of their fracture remnants.

scholarly journals CO2 Curing Efficiency for Cement Paste and Mortars Produced by a Low Water-to-Cement Ratio

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3883
Author(s):  
Seong Ho Han ◽  
Yubin Jun ◽  
Tae Yong Shin ◽  
Jae Hong Kim
Keyword(s):  
Cement Paste ◽  
Pressure Vessel ◽  
Gas Pressure ◽  
Strength Development ◽  
Co2 Uptake ◽  
Cement Pastes ◽  
Co2 Gas ◽  
Cement Ratio ◽  
Mix Proportion ◽  
Water To Cement Ratio

Curing by CO2 is a way to utilize CO2 to reduce greenhouse gas emissions. Placing early-age cement paste in a CO2 chamber or pressure vessel accelerates its strength development. Cement carbonation is attributed to the quickened strength development, and CO2 uptake can be quantitatively evaluated by measuring CO2 gas pressure loss in the pressure vessel. A decrease in CO2 gas pressure is observed with all cement pastes and mortar samples regardless of the mix proportion and the casting method; one method involves compacting a low water-to-cement ratio mix, and the other method comprises a normal mix consolidated in a mold. The efficiency of the CO2 curing is superior when a 20% concentration of CO2 gas is supplied at a relative humidity of 75%. CO2 uptake in specimens with the same CO2 curing condition is different for each specimen size. As the specimen scale is larger, the depth of carbonation is smaller. Incorporating colloidal silica enhances the carbonation as well as the hydration of cement, which results in contributing to the increase in the 28-day strength.

scholarly journals Hydration processes of cement paste-an EPR study

2010 ◽  
Vol 7 (1) ◽  
pp. 215-219
Author(s):  
R. Gopalakrishnan ◽  
D. Govindarajan
Keyword(s):  
Setting Time ◽  
Electron Paramagnetic Resonance Study ◽  
Hydration Time ◽  
Time Intervals ◽  
Paramagnetic Resonance ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Final Setting Time ◽  
Water To Cement Ratio ◽  
Electron Paramagnetic

The present works reports the hydration processes of Portland cement through Electron paramagnetic resonance study. Cement pastes in a Water to cement ratio (W/C) of 0.4 at different hydration time intervals have been prepared. The g-factor of Fe(III) and Mn(II) impurities at different hydration ages has been related to changes in setting time of cement. Both gFe and gMn values are reach a maximum values at final setting time of OPC paste.

Effect of Fly Ash Incorporation on Rheology of Cement Pastes

1986 ◽  
Vol 86 ◽  
Author(s):  
M. Rattanussorn ◽  
D. M. Roy ◽  
R. I. A. Malek
Keyword(s):  
Fly Ash ◽  
Chemical Composition ◽  
Zeta Potential ◽  
Spherical Shape ◽  
Ash Content ◽  
Type I ◽  
Special Effect ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Water To Cement Ratio

ABSTRACTThe predominant spherical shape of fly ash particles combined with mainly glassy composition and texture of its surfaces have a special effect on rheology of cement pastes containing fly ash. The early ages rheological behavior of cement pastes (ASTM Type I) incorporating 30% low-calcium fly ash was monitored by measuring viscosity of the fresh pastes prior to initial hardening and stiffening (up to −2 hours) as a function of time. The viscosities were determined using a co-axial rotoviscometer (HAAKE). The effects of fly ash content, water to cement ratio, and presence and concentration of superplasticizer, were evaluated. In addition, the dispersivity of fly ash spheres was evaluated by determining the zeta-potential of fly ash suspensions in water using a microelectrophoresis technique and the results were correlated to the chemical composition of fly ash as well as the viscosities of fresh pastes.

Nuclear Magnetic Resonance Studies on Microstructure of Cement Pastes

2010 ◽  
Vol 177 ◽  
pp. 518-521 ◽  
Author(s):  
Dan Jin ◽  
Wu Yao ◽  
An Ming She ◽  
Xiao Yan Liu
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Fast Diffusion ◽  
Cement Pastes ◽  
Bulk Fluid ◽  
Cement Ratio ◽  
Water To Cement Ratio ◽  
The Difference ◽  
Nuclear Magnetic

For water filled porous materials, the difference between the relaxation time of molecules at the pore surface and the relaxation time of molecules in the bulk fluid can be interpreted by a fast diffusion model. With this model, the nuclear magnetic resonance (NMR) can be applied to investigate the microstructure of cement pastes. The cement pastes we tested are two series, one is of same water to cement ratio (w/c=0.4) at different curing time (7d, 28d and 90d), the other is of different water to cement ratio (w/c=0.3, 0.4 and0.5, respectively) at the same curing day. Comparing results by NMR method with those by mercury intrusion porosimetry (MIP) shows that NMR is a convenient and nondestructive way to probe pore distribution of cement pastes.

scholarly journals Effect of Boron and Water-to-Cement Ratio on the Performances of Laboratory Prepared Belite-Ye’elimite-Ferrite (BYF) Cements

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4862
Author(s):  
Raquel Pérez-Bravo ◽  
Alejandro Morales-Cantero ◽  
Margherita Bruscolini ◽  
Miguel A. G. Aranda ◽  
Isabel Santacruz ◽  
...  
Keyword(s):  
Particle Size ◽  
Rietveld Method ◽  
Phase Assemblage ◽  
Calorimetric Study ◽  
Cement Ratio ◽  
Degree Of Hydration ◽  
Rheological Measurements ◽  
Water To Cement Ratio ◽  
Mechanical Strengths ◽  
Heat Released

The effect of superplasticiser, borax and the water-to-cement ratio on BYF hydration and mechanical strengths has been studied. Two laboratory-scale BYF cements—st-BYF (with β-C2S and orthorhombic C4A3S¯) and borax-activated B-BYF (with α’H-C2S and pseudo-cubic C4A3S¯)—have been used, and both show similar particle size distribution. The addition of superplasticiser and externally added borax to BYF pastes has been optimised through rheological measurements. Optimised superplasticiser contents (0.3, 0.4 and 0.1 wt % for st-BYF, B-BYF and st-BYF with externally added 0.25 wt % B2O3, respectively) result in low viscosities yielding homogeneous mortars. The calorimetric study revealed that st-BYF is more reactive than B-BYF, as the values of heat released are 300–370 J/g and 190–210 J/g, respectively, after 7 days of hydration; this fact is independent of the water-to-cement ratio. These findings agree with the higher degree of hydration at 28 days of β-C2S in st-BYF (from 45 to 60%) than α’H-C2S in B-BYF (~20 to 30%). The phase assemblage evolution has been determined by LXRPD coupled with the Rietveld method and MAS-NMR. The formation of stratlingite is favoured by increasing the w/c ratio in both systems. Finally, the optimisation of fresh BYF pastes jointly with the reduction of water-to-cement ratio to 0.40 have allowed the achieving of mortars with compressive strengths over 40 MPa at 7 days in all systems. Moreover, the st-BYF mortar, where borax was externally added, achieved more than 70 MPa after 28 days. The main conclusion of this work does not support Lafarge’s approach of adding boron/borax to the raw meal of BYF cements. This procedure stabilises the alpha belite polymorph, but its reactivity, in these systems, is lower and the associated mechanical strengths poorer.

Effect of water-to-cement ratio induced hydration on the accelerated carbonation of cement pastes

2021 ◽  
Vol 280 ◽  
pp. 116914
Author(s):  
Hamideh Mehdizadeh ◽  
Xiaoxiao Jia ◽  
Kim Hung Mo ◽  
Tung-Chai Ling
Keyword(s):  
Accelerated Carbonation ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Effect Of Water ◽  
Water To Cement Ratio
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