scholarly journals Impacts of Space Restriction on the Microstructure of Calcium Silicate Hydrate

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3645
Author(s):  
Yue Zhou ◽  
Zhongping Wang ◽  
Zheyu Zhu ◽  
Yuting Chen ◽  
Linglin Xu ◽  
...  
Keyword(s):  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Degree Of Polymerization ◽  
Hydration Products ◽  
Hydration Kinetics ◽  
Water To Cement Ratio ◽  
Microstructure Morphology ◽  
Water Filling ◽  
High Degree ◽  
Space Restriction

The effect of hydration space on cement hydration is essential. After a few days, space restriction affects the hydration kinetics which dominate the expansion, shrinkage and creep of cement materials. The influence of space restriction on the hydration products of tricalcium silicate was studied in this paper. The microstructure, morphology and composition of calcium silicate hydrate (C-S-H) were explored from the perspective of a specific single micropore. A combination of Raman spectra, Fourier transform infrared spectra, scanning electron microscopy and energy dispersive X-ray spectroscopy were employed. The results show that space restriction affects the structure of the hydration products. The C-S-H formed in the micropores was mainly composed of Q3 silicate tetrahedra with a high degree of polymerization. The C-S-H formed under standard conditions with a water to cement ratio of 0.5 mostly existed as Q2 units. Space restriction during hydration is conducive to the formation of C-S-H with silica tetrahedra of a high polymerization degree, while the amount of water filling the micropore plays no obvious role on the polymeric structure of C-S-H during hydration.

Xonotlite and Hillebrandite as Model Compounds for Calcium Silicate Hydrate Seeding in Cementitious Materials

2020 ◽  
pp. 036119812094320
Author(s):  
Elisabeth John ◽  
Christian Lehmann ◽  
Dietmar Stephan
Keyword(s):  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Model Compound ◽  
Hydration Product ◽  
Cementitious Materials ◽  
Nucleation Site ◽  
Hydration Products ◽  
Sem Images ◽  
Pit Formation ◽  
Nanoparticle Additives

The demand for more environmentally friendly cement with no disadvantages in relation to hydration activity has led to the development of various additives to accelerate cement hydration. As calcium silicate hydrate (C-S-H) is the major hydration product of cement and is responsible for its mechanical properties, it plays an outstanding role in the discussion of nanoparticle additives. Nevertheless, the investigation of its mechanism of action is complicated by the similarity of its properties to those of the C-S-H that forms as an initial hydration product. Crystalline C-S-H phases, on the other hand, can be easily distinguished from the original hydration products, which makes them a valuable model compound for studying the mechanisms of nucleation seeding in cementitious materials. In this paper, the effect of crystalline types of C-S-H as nucleation seeds are presented. Xonotlite and hillebrandite were thoroughly characterized using nuclear magnetic resonance, X-ray diffractometry (XRD), scanning electron microscopy (SEM), and infrared spectroscopy (IR) and were then used as an admixture for alite pastes. Low-vacuum SEM images of the hydrated pastes revealed that xonotlite can significantly promote the visible etch pit formation on C3S clinker particles, which was not found to be true for hillebrandite. Whether the phases act as a nucleation site is assumed to be strongly dependent on the mineralogy: hillebrandite appeared to be heavily overgrown, but xonotlite did not show any hydration products on its surfaces after the same hydration time of up to 24 h. The diverse effect of the minerals was confirmed by the accelerating behavior in isothermal heat flow calorimetry and by XRD.

scholarly journals Influence of Mortar Incorporating Silica Based Waste Material on the Formation of C-S-H and Mechanical Strength Properties

2014 ◽  
Vol 695 ◽  
pp. 647-650 ◽  
Author(s):  
Nafisa Tamanna ◽  
Norsuzailina Mohamed Sutan ◽  
Ibrahim Yakub ◽  
Delsye Teo Ching Lee ◽  
Ezzaq Farhan Ahmad
Keyword(s):  
Compressive Strength ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Glass Powder ◽  
Strength Properties ◽  
Particle Sizes ◽  
Replacement Level ◽  
Cement Ratio ◽  
Water To Cement Ratio ◽  
Partial Cement Replacement

Recent studies have been carried out to utilize waste glass in construction as partial cement replacement. This paper investigates the formation of Calcium Silicate Hydrate (C-S-H) and strength characteristics of mortar in which cement is partially replaced with glass powder by replacement level of 10%, 20% and 30%. Mortar cubes containing varying particle sizes in the ranges of 150-75μm, 63-38 μm and lower than 38 μm and in a water to cement ratio of 0.45 and 0.40 have been prepared. Replacement by 10% cement with glass powder reveals high compressive strength and produces more C-S-H at 28 days than other levels of replacement.

The Alkaline Activation of Calcium Oxide on Phosphorous Slag Powder Cementing Material in Autoclaved Curing

2011 ◽  
Vol 239-242 ◽  
pp. 2317-2322
Author(s):  
Jian Xin Cao ◽  
Lin Yang ◽  
Qian Lin ◽  
Guang Shan Bai ◽  
Fei Liu
Keyword(s):  
Calcium Oxide ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Mechanical Performance ◽  
Hydration Products ◽  
Alkaline Activation ◽  
Slag Powder ◽  
Autoclave Curing ◽  
Cementing Material ◽  
Phosphorous Slag

This research attempts to test the mechanical properties of calcium oxide-phosphorous slag powder cementing material under autoclave curing condition. X-ray diffraction, scanning electron microscope-energy dispersion scanner and differential scanning calorimetry-thermogravimetry were adopted to characterize the performance of the hydration products and microstructure of phosphorous slag powder cementing material autoclaved product. The research findings showed that under the condition of autoclave curing, doping calcium oxide would activate preferable property of hydration and hardening of phosphorous slag powder cementing material, and the best strength of the cementing material would be achieved with optimal doping of 15% (in mass) compound calcium oxide. With the effect of the alkaline activation of calcium oxide, there mainly remained the calcium silicate hydrate gel and Al-calcium silicate hydrate in hydration products of phosphorous slag powder cementing material. Excess calcium oxide made alkalinity of calcium silicate hydrate gel change from low to high, thus leading to the decline of mechanical performance of autoclave products.

Hydration Products, Microstructure and Durability of Concrete with Metakaolin Addition

2016 ◽  
Vol 680 ◽  
pp. 420-428
Author(s):  
Qiu Li ◽  
Hai Ning Geng ◽  
Yun Huang ◽  
Zhong He Shui
Keyword(s):  
Diffusion Coefficient ◽  
Calcium Hydroxide ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Analytical Techniques ◽  
Pozzolanic Reaction ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Hydration Products ◽  
Durability Of Concrete

The durability, microstructure and hydration products of concrete containing 0-6wt% metakaolin (MK) were studied by analytical techniques. The hydration products were calcium hydroxide (CH), ettringite and calcium silicate hydrate gels in the control concrete, and additional monocarboaluminate and hemicarboaluminate were identified in concrete containing MK. CH content decreased by 28 days hydration in concrete containing MK, due to the pozzolanic reaction between MK and CH. Chloride diffusion coefficient decreased with the increase of MK content. By addition of 6wt% MK, chloride diffusion coefficient decreased by 60%.

scholarly journals Effect of nano silica (SiO2) on the hydration kinetics of cement

2019 ◽  
Vol 39 (3) ◽  
pp. 248-260 ◽  
Author(s):  
Taher Abu-Lebdeh ◽  
Relly Victoria Virgil Petrescu ◽  
Moayyad Al-Nasra ◽  
Florian Ion Tiberiu Petrescu
Keyword(s):  
Compressive Strength ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Hydration Process ◽  
Strength Development ◽  
Hardened Cement ◽  
Nano Silica ◽  
Hydration Kinetics ◽  
Drastic Increase ◽  
Curing Method

This study investigated the influence of adding nano silica (SiO2) on the cement hydration process, particularly on the formation of calcium silicate hydrate (C-S-H) at different stages of hydration. The study investigated the effect of adding nano-silica on the mechanical properties of the hardened cement corresponding to the formation of C-S-H during the hydration process of a cement paste. Specimens made up of four different percentage of nano silica (0%, 1%, 3% and 5%) were tested at different stages of hydration ranging from 3 to 56 days. The effect of nano-silica on the compressive strength, stressstrain, and elastic modulus of nano-cement was examined using MTS and Forney testing machines. The signature phase and formation of C-S-H and calcium hydroxide (CH) were monitored using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The study also investigated the effect of curing method (vacuum and water curing) on the strength development. The experimental results show that the formation of calcium silicate hydrate (C-S-H) increases significantly during the early stages of hydration which correspond to the drastic increase in compressive strength. The formation of C-S-H continues to increase throughout the 56 days but at a moderate rate. The results reveal that 1% of nano silica by volume of cement is the optimum ratio that yields the maximum strength. The results also indicated that the strength of the traditional water cured specimens were higher than that of vacuum cured specimens.

Probing Nanostructure of Calcium Silicate Hydrate by AFM and Nanoindentation

2013 ◽  
Vol 539 ◽  
pp. 80-83
Author(s):  
Kang Liang ◽  
Wu Yao ◽  
Lin Jie Chen ◽  
Qun Gao
Keyword(s):  
Mechanical Properties ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Maximum Load ◽  
Force Microscopy ◽  
Atomic Force ◽  
Water To Cement Ratio ◽  
Binding Phase ◽  
Portland Cement Paste ◽  
Morphology And Mechanical Properties

It is important to study the nanostructure and mechanical properties of calcium silicate hydrate at the nanoscale for it is the main binding phase in Portland cement paste. In this paper, atomic force microscopy and nanoindentation (NI) were combine used to determine the morphology and mechanical properties of Calcium Silicate Hydrate (C-S-H) at microscale. It is found that C-S-H is made of globules from size of 50 nm to 300 nm irrelevant with water-to-cement ratio and ages in nanostructure, and we suggest that the maximum load for NI testing of the C-S-H is no more than 2 mN.

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