scholarly journals Use Of Olivine For The Production Of MgO-SiO2 Binders

2021 ◽  
Vol 7 ◽  
Author(s):  
Scott Allan Nye ◽  
Shah Vineet ◽  
Oze Christopher ◽  
Shanks Barnaby ◽  
Cheeseman Chris
Keyword(s):  
Silica Fume ◽  
Isothermal Calorimetry ◽  
Magnesium Silicate ◽  
Binder System ◽  
Hydration Products ◽  
Cementitious Binder ◽  
Binding Component

The potential for using MgO and SiO2, recovered from olivine, was investigated for use as a cementitious binder system. The MgO to SiO2 proportion for the binder was fixed at 1:1. The nature of the hydration products were characterized using a variety of techniques including isothermal calorimetry, XRD, FTIR, and SEM. The primary binding component of the paste was determined to be magnesium silicate hydrate (M-S-H). The recovered silica exhibited faster reactivity compared to commercially available silica fume. Compressive strengths in excess of 20 MPa were obtained using the materials recovered from olivine.

scholarly journals Stabilization/Solidification of Strontium Using Magnesium Silicate Hydrate Cement

Processes ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 163
Author(s):  
Tingting Zhang ◽  
Jing Zou ◽  
Yimiao Li ◽  
Yuan Jia ◽  
Christopher R. Cheeseman
Keyword(s):  
Magnesium Oxide ◽  
Silica Fume ◽  
Phase Formation ◽  
Magnesium Silicate ◽  
National Standard ◽  
Leaching Rate ◽  
Hydration Products ◽  
Hydrate Cement ◽  
Leaching Fraction ◽  
New Phase

Magnesium silicate hydrate (M–S–H) cement, formed by reacting MgO, SiO2, and H2O, was used to encapsulate strontium (Sr) radionuclide. Samples were prepared using light-burned magnesium oxide and silica fume, with sodium hexametaphosphate added to the mix water as a dispersant. The performance of the materials formed was evaluated by leach testing and the microstructure of the samples was also characterized. The stabilizing/solidifying effect on Sr radionuclide in the MgO–SiO2–H2O system with low alkalinity is demonstrated in the study. The leaching rate in a standard 42-day test was 2.53 × 10−4 cm/d, and the cumulative 42-day leaching fraction was 0.06 cm. This meets the relevant national standard performance for leaching requirements. Sr2+ was effectively incorporated into the M–S–H hydration products and new phase formation resulted in low Sr leaching being observed.

scholarly journals Control of Drying Shrinkage of Magnesium Silicate Hydrate Gel Cements

2016 ◽  
Vol 709 ◽  
pp. 109-113 ◽  
Author(s):  
Ting Ting Zhang ◽  
Xiao Min Liang ◽  
M. Lorin ◽  
Zhen Lin Wu ◽  
Chris Cheeseman ◽  
...  
Keyword(s):  
Portland Cement ◽  
Magnesium Oxide ◽  
Silica Fume ◽  
Drying Shrinkage ◽  
Magnesium Silicate ◽  
Hydration Products ◽  
Cement Ratio ◽  
Water To Cement Ratio ◽  
Order Of Magnitude ◽  
Forced Drying

Cracks were observed when the magnesium silicate hydrate gel cement (prepared by 40% MgO/ 60% silica fume) was dried. This drying cracking is believed to be caused when unbound water evaporates from the binder. The shrinkage upon forced drying to 200 °C of mortars made up from a reactive magnesium oxide, silica fume and sand was measured using dilatometry. The magnitude of the drying shrinkage was found to decrease when more sand or less water was added to the mortars and can be as low as 0.16% for a mortar containing 60 wt% sand and a water to cement ratio of 0.5, which is of a similar order of magnitude as observed in Portland cement based mortars and concretes. A simple geometrical interpretation based on packing of the particles in the mortar can explain the observed drying shrinkages and based on this analysis the drying shrinkage of the hydration products at zero added solid is estimated to be 7.3% after 7 days of curing.

scholarly journals Effect of the MgO/Silica Fume Ratio on the Reaction Process of the MgO–SiO2–H2O System

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 80 ◽  
Author(s):  
Zhaoheng Li ◽  
Yudong Xu ◽  
Hao Liu ◽  
Jianwei Zhang ◽  
Jiangxiong Wei ◽  
...  
Keyword(s):  
Reaction Kinetics ◽  
Silica Fume ◽  
Main Product ◽  
Magnesium Silicate ◽  
Reaction Process ◽  
Reaction Products ◽  
Degree Of Reaction ◽  
Reaction Thermodynamics ◽  
Experimental Values ◽  
Kinetics Of

In order to clarify the effect of the MgO–silica fume (SF) ratio on the reaction process of the MgO–SiO2–H2O system, the reaction products and degree of reaction were characterized. Furthermore, the parameters of the reaction thermodynamics were calculated and the reaction kinetics were deduced. The results indicate that a large amount of Mg(OH)2 and small quantities of magnesium silicate hydrate (M–S–H) gels were generated upon dissolution of MgO. However, the M–S–H gels were continuously generated until the SF or Mg(OH)2 was consumed completely. For a MgO dosage less than 50% of the total MgO–SiO2–H2O system, the main product was M–S–H gel, while for a MgO dosage greater than 50%, the main product was Mg(OH)2. The results indicate that M–S–H gels have greater stability than Mg(OH)2, and the final reaction product was prone to be M–S–H gels. Based on the experimental values, an equation is proposed for the reaction kinetics of MgO.

Evaluation the Strength of Cement Systems, Modified by Accelerators

2014 ◽  
Vol 670-671 ◽  
pp. 339-343 ◽  
Author(s):  
Aleksey Adamtsevich ◽  
Andrey Pustovgar ◽  
Stanislav Pashkevich ◽  
Aleksey Eremin ◽  
Andrey Zhuravlev
Keyword(s):  
Heat Release ◽  
Experimental Research ◽  
Growth Kinetics ◽  
Cement Hydration ◽  
Integral Curve ◽  
Isothermal Calorimetry ◽  
Growth Dynamics ◽  
Binder System ◽  
Methods Development ◽  
Kinetics Of

Nowadays, there is a great demand for the accelerated hardening construction mixtures. That causes the necessity to the methods development for testing the effectiveness of accelerators, well as the analysis of kinetics of cement systems hydration in the early stages of hardening. This paper presents the results of an experimental research of interrelation between the growth kinetics of cement-based binder system strength and the heat release for pure cement hydration. How it was found, two compositions of construction mix, which are identical in mineral composition and differ in the presence of mono-functional accelerator, a comparison of strength growth dynamics can be carried out indirectly via the integral curve of heat release, obtained using the method of isothermal calorimetry.

Hydration Process of Portland Cement Blended with Silica Fume

2013 ◽  
Vol 699 ◽  
pp. 578-583 ◽  
Author(s):  
Neven Ukrainczyk ◽  
Jure Zlopasa ◽  
Eduard Koenders
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
Isothermal Calorimetry ◽  
Construction Materials ◽  
Radical Change ◽  
Sustainable Construction ◽  
Hydration Kinetics ◽  
Replacement Ratio ◽  
Cement Production ◽  
Ultrasound Bath

The enormous carbon footprint associated with the global cement production (5-7%) asks for a radical change in the use of sustainable replacement materials in concrete. Replacement of cement by pozzolanic waste materials, being a by-product from industrial processes, has been widely recognized as the most promising route towards sustainable construction materials. This paper presents experimental study on hydration of commercial Portland cement blended with silica fume in replacement ratio of 15 mass %. Isothermal calorimetry was employed to monitor the hydration kinetics. Thermogravimetric analysis coupled by differential scanning calorimeter (TG/DSC) was used to investigate the formed hydration products at 1, 3, 7, and 28 days of hydration. Two different approaches for a dispersion of silica fume in cement paste were compared: ultrasound bath and addition of superplasticizer (polycarboxylic ether based).

The Pozzolanic Reaction of Silica Fume

2012 ◽  
Vol 1488 ◽  
Author(s):  
Ole M. Jensen
Keyword(s):  
Silica Fume ◽  
High Performance ◽  
Cement Hydration ◽  
Theoretical Calculations ◽  
Pozzolanic Reaction ◽  
Interfacial Transition Zone ◽  
Strength Development ◽  
Micro Structure ◽  
Cementitious Binder ◽  
Portland Cement Hydration

ABSTRACTSilica fume is a very important supplementary cementitious binder in High-Performance and Ultra High-Performance Concretes. Through its pozzolanic reaction the silica fume densifies the concrete micro-structure, in particular it strengthens the paste-aggregate interfacial transition zone. In the present paper different aspects of the pozzolanic reaction of silica fume are investigated. These include chemical shrinkage, isothermal heat development and strength development. Key data for these are given and compared with theoretical calculations, and based on presented measurements the energy of activation of the pozzolanic reaction of silica fume is estimated. The results show that the pozzolanic reaction of silica fume has notable differences from Portland cement hydration.

scholarly journals An Investigation on Strength Development of Cement with Cenosphere and Silica Fume as Pozzolanic Replacement

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
K. Senthamarai Kannan ◽  
L. Andal ◽  
M. Shanmugasundaram
Keyword(s):  
Silica Fume ◽  
Strength Loss ◽  
Strength Reduction ◽  
Strength Development ◽  
Test Results ◽  
Hydration Products

In the detailed study presented in this paper, an attempt was made to study the strength of cement when cenosphere (CS) and silica fume (SF) were used as replacement. Tests were carried out on mix with cenosphere as replacement for cement which has 12% of constant replacement of silica fume to the mass of cement, and this is made to stabilize the strength which was lost due to addition of cenosphere. From the test results, it was concluded that the strength loss of binder due to replacement of cenosphere can be stabilized by silica fume and still a safe value of strength can be achieved. Furthermore, the strength reduction is due to the consumption of hydration products and cloggy microstructure as observed in this study.

scholarly journals Characterization of Magnesium Silicate Hydrate (MSH) Gel Formed by Reacting MgO and Silica Fume

Materials ◽  
2018 ◽  
Vol 11 (6) ◽  
pp. 909 ◽  
Author(s):  
Tingting Zhang ◽  
Jing Zou ◽  
Baomin Wang ◽  
Zhenlin Wu ◽  
Yuan Jia ◽  
...  
Keyword(s):  
Silica Fume ◽  
Magnesium Silicate

Hydration of sodium phosphate-modified high alumina cement

1994 ◽  
Vol 9 (5) ◽  
pp. 1291-1298 ◽  
Author(s):  
Weiping Ma ◽  
Paul W. Brown
Keyword(s):  
Isothermal Calorimetry ◽  
High Strength ◽  
High Alumina ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Alumina Cement ◽  
X Ray ◽  
Morphological Variations ◽  
High Alumina Cement ◽  
Sodium Phosphates

High strength can be achieved in high alumina cement (HAC) through the incorporation of phosphate-based additions at levels of 10 and 20 wt. %. In order to establish the mechanism that results in higher strength, the effects of a variety of condensed sodium phosphates (NaPO3)n, (NaPO3)n · Na2O, Na5P3O10, and (NaPO3)3 were studied. The influence of these additions on the kinetics of hydration was studied using isothermal calorimetry. The phosphatic additions enhanced reactivity, but x-ray diffraction analyses did not reveal evidence of new crystalline phosphate-containing hydration products. Microstructural evolution was examined in real time using environmental SEM, and hydration products exhibiting distinct morphologies were observed. The features exhibited ranged from amorphic to polygonal shapes, plates, and fibers. These frequently formed between crystalline calcium aluminate hydrate grains and by doing so appear to provide a means to enhance the strengths of these cements. In spite of the morphological variations, companion energy dispersive x-ray analysis showed that the compositions of these products did not vary widely. Their ranges of compositions are 52-60 wt. % Al2O3, 20-26 wt. % P2O5, and 20-24 wt. % CaO.

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.

Sign in / Sign up

Export Citation Format

Share Document