Synergistic effects of three-dimensional graphene and silica fume on mechanical and chloride diffusion properties of hardened cement paste

2022 ◽  
Vol 316 ◽  
pp. 125756
Author(s):  
Jingwei Ying ◽  
Zhijun Jiang ◽  
Jianzhuang Xiao
Keyword(s):  
Silica Fume ◽  
Cement Paste ◽  
Synergistic Effects ◽  
Three Dimensional ◽  
Chloride Diffusion ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Diffusion Properties

NMR T1–T2 correlation analysis of molecular absorption inside a hardened cement paste containing silanised silica fume

2018 ◽  
Vol 117 (7-8) ◽  
pp. 1000-1005 ◽  
Author(s):  
Calin Cadar ◽  
Andrea Cretu ◽  
Marioara Moldovan ◽  
Carlos Mattea ◽  
Siegfried Stapf ◽  
...  
Keyword(s):  
Correlation Analysis ◽  
Silica Fume ◽  
Cement Paste ◽  
Hardened Cement ◽  
Molecular Absorption ◽  
Hardened Cement Paste

scholarly journals Effect of Ultrafine Additives on the Morphology of Cement Hydration Products

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1002
Author(s):  
Grigory Yakovlev ◽  
Rostislav Drochytka ◽  
Gintautas Skripkiunas ◽  
Larisa Urkhanova ◽  
Irina Polyanskikh ◽  
...  
Keyword(s):  
Silica Fume ◽  
Cement Paste ◽  
Cement Hydration ◽  
Chemical Reactivity ◽  
Xrd Analysis ◽  
Hardened Cement ◽  
Hydration Products ◽  
Hardened Cement Paste ◽  
X Ray ◽  
Strong Adhesion

The present research is focused on the investigation of the influence of ultrafine additives on the structure formation of hardened cement paste and the establishment of the mechanisms of the morphological transformations, which determine the properties of hydrated products. In the course of the research, the modification of ordinary Portland cement was performed by the suspension of multi-walled carbon nanotubes (MWCNTs), carbon black (CB) paste, and silica fume (SF). Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) microanalysis, X-ray diffraction (XRD) analysis, thermal analysis, and Fourier-transform infrared (FTIR) spectroscopy were used to study cement hydration products. The morphology of hardened cement paste depends on the chemical reactivity of additives, their geometry, and their genesis. The action mechanism of the inert carbon-based additives and pozzolanic silica fume were considered. The cement hydration products formed in the process of modification by both types of ultrafine additives are described. In the case of the modification of cement paste by inert MWCNTs and CB paste, the formation of cement hydration products on their surface without strong adhesion was observed, whereas in the case of the addition of SF separately and together with MWCNTs, the strong adhesion of additives and cement hydration products was noted.

scholarly journals Flexural strength of silica fume, fly ash, and metakaolin of hardened cement paste after exposure to elevated temperatures

2021 ◽  
Author(s):  
Nabil Abdelmelek ◽  
Eva Lubloy
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Cement Paste ◽  
Elevated Temperatures ◽  
The Other ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Structural Element ◽  
Pozzolanic Material ◽  
Pozzolanic Materials

AbstractThe mechanical properties of concrete based mainly on flexural and compressive bearing capacity. Generally, researchers have an interest in the evaluation of compression property through the importance of the flexural performance of the material in the constructions, namely the significance of each mechanical property based upon the position of the structural element. The present experimentally work is directed toward improving the flexural strengths performance of ordinary hardened cement paste (HCP) at ambient and after elevated temperatures exposure. The used parameters were different pozzolanic materials with different replacements ratios to cement mass and different levels of temperature. Results proved the significant contribution of pozzolanic material to enhance the flexural properties of HCP after being exposed to elevated temperatures. The low content of CaO, the high grinding fineness, and the physical morphology of the used pozzolanic materials, made their adoption effective to HCP after exposure to elevated temperatures. Using 3%, 12%, and 15% of silica fume (SF), metakaolin (MK), and fly ash (FA), respectively, showed the highest heat endurance among the other replacements. However, the optimum replacement of MK has shown a better heat endurance than the optimum replacements of SF and FA. On the other hand, the spalling has occurred at high replacements of SF. Finally, the results are supported by means of thermo-gravimetric, SEM, and computed tomography investigations.

On Effect of Superplasticizers and Mineral Additives on Creep Factor of Hardened Cement Paste and Concrete

2017 ◽  
Vol 265 ◽  
pp. 109-113 ◽  
Author(s):  
G.V. Nesvetaev ◽  
I.V. Korchagin ◽  
Y.Y. Lopatina
Keyword(s):  
Silica Fume ◽  
Cement Paste ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
White Ash ◽  
The Relationship ◽  
Mineral Additives

The relationship between the creep factor of concrete and hardened cement paste and the E-modulus of aggregate and evaluation of the effects of some modifiers on the creep factor of the hardened cement paste was determined. The influence of the SP on the creep factor of hardened cement paste is ambiguous: SP may increase, decrease, or not change the creep factor. The possible deviation of creep factor of hardened cement paste with the SP in certain cases can be up to 4 times. The average statistical increase in the creep factor of hardened cement paste may be 7 to 35%. The creep factor of regular concrete is equal 0.43 - 0.9 value of the creep factor of hardened cement paste. Superplasticizers may increase the creep of concrete up to 30% and in some cases - up to 3 times. Silica fume, metakaolin, white ash, including when used with the superplasticizers, may reduce the creep of concrete from 15 to 50%. An equation was suggested to calculate the E-modulus of concrete with the volume of hardened cement paste of 0.27 - 0.35 as a function of E-modulus of hardened cement paste and E-modulus of the aggregates.

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