The Development of Durable Cementitious Materials for Use in a Nuclear Fuel Waste Disposal Facility

1985 ◽  
Vol 50 ◽  
Author(s):  
N. C. Burnett ◽  
R. D. Hooton ◽  
R. B. Heimann ◽  
M. Onofrei
Keyword(s):  
Silica Fume ◽  
Saline Solution ◽  
Cementitious Materials ◽  
Canadian Shield ◽  
Potassium Ions ◽  
Leaching Tests ◽  
Short Term ◽  
Supplementary Cementing Materials ◽  
Disposal Facility ◽  
Nuclear Fuel Waste

AbstractThis paper describes the work on cement paste development and short-term leaching tests in Standard Canadian Shield Saline Solution (SCSSS) in the presence of bentonite at 150°C. It has been found that:-supplementary cementing materials such as silica fume or fly ash could significantly improve the properties of sulphate resistant portland cement (SRPC), in particular, permeability to water and pore size distribution.-the addition of bentonite suppressed the normal tendency of the pH of groundwater to increase rapidly in the presence of cement.-the presence of bentonite increased the release of potassium ions from the cements.-– SRPC blended with 20% silica fume resulted in a groundwater pH lower than that of SRPC, with and without bentonite. Moreover, its cumulative fraction of release of potassium was significantly lower than that of SRPC.

scholarly journals Short-Term Performance of Sustainable Silica Fume Mortars Exposed to Sulfate Attack

2018 ◽  
Vol 10 (7) ◽  
pp. 2517 ◽  
Author(s):  
José Ortega ◽  
María Esteban ◽  
Mark Williams ◽  
Isidro Sánchez ◽  
Miguel Climent
Keyword(s):  
Silica Fume ◽  
Pore Network ◽  
Cementitious Materials ◽  
Short Term ◽  
Cement Production ◽  
Sustainable Environment ◽  
Sodium Sulfates ◽  
Term Performance ◽  
State Ionic

Nowadays, the reuse of wastes is essential in order to reach a more sustainable environment. The cement production results in CO2 emissions which significantly contribute to anthropogenic greenhouse gas emissions. One way to reduce them is by partially replacing clinker by additions, such as silica fumes or other wastes. On the other hand, the pore structure of cementitious materials has a direct influence on their service properties. One of the most popular techniques for characterizing the microstructure of those materials is mercury intrusion porosimetry. In this work, this technique has been used for studying the evolution of the pore network of mortars with different percentages of silica fume (until 10%), which were exposed to aggressive sodium and magnesium sulfate solutions up to 90 days. Between the results of this technique, intrusion-extrusion curves and logarithms of differential intrusion volume versus pore size curves were studied. This characterization of the pore network of mortars has been complemented with the study of their compressive strength and their steady-state ionic diffusion coefficient obtained from samples’ resistivity. Generally, silica fume mortars showed different performance depending on the aggressive condition, although the greatest deleterious effects were observed in the medium with presence of both magnesium and sodium sulfates.

The Effect of Silica Fume and Water/Cement Ratio on the Hydraulic Conductivity of Cement-Based Grout

1990 ◽  
Vol 212 ◽  
Author(s):  
A. A. Al-Manaseer ◽  
M. Onofrei ◽  
M. N. Gray ◽  
B. Shenton
Keyword(s):  
Hydraulic Conductivity ◽  
Silica Fume ◽  
High Performance ◽  
Fractured Rock ◽  
Laboratory Data ◽  
Field Work ◽  
Cementitious Materials ◽  
In Situ Experiments ◽  
Underground Research Laboratory ◽  
Nuclear Fuel Waste

ABSTRACTIn situ experiments at Atomic Energy of Canada Limited’s Underground Research Laboratory have demonstrated that a specially developed high-performance cement-based grout, called the reference grout, consisting of 90% sulphate-resistant cement (Canadian Type 50), 10% silica fume (SF) and superplasticizer can seal very fine fissures in granitic rock. Studies are now in progress to determine the longevity of these materials. This paper describes progress in studies of the hydraulic conductivity (i.e. coefficient of permeability), K, of the grout at water/cementitious materials ratios, w/c, between 0.4 and 0.8. The K was assessed with the grouts under compressive and tensile stress using specially designed radial flow permeameters. The results confirm that the K of the reference grout is two to three orders of magnitude lower than that typically observed for intact granite rock (10−12 m/s). Moreover, the data show that adding silica fume and reducing the w/c decreases K. The hydraulic conductivity data coupled with field work and other laboratory data strongly suggest that the reference grout can be successfully used to seal finely fractured rock in the vicinity of a nuclear fuel waste disposal vault.

scholarly journals Rotator Cuff Calcific Tendinitis: Does Warm Saline Solution Improve the Short-term Outcome of Double-Needle US-guided Treatment?

Radiology ◽  
2012 ◽  
Vol 262 (2) ◽  
pp. 560-566 ◽  
Author(s):  
Luca Maria Sconfienza ◽  
Michele Bandirali ◽  
Giovanni Serafini ◽  
Francesca Lacelli ◽  
Alberto Aliprandi ◽  
...  
Keyword(s):  
Rotator Cuff ◽  
Saline Solution ◽  
Calcific Tendinitis ◽  
Short Term ◽  
Term Outcome ◽  
Short Term Outcome

Modeling of Alteration Behavior on Blended Cementitious Materials

2011 ◽  
Author(s):  
Hitoshi Owada ◽  
Tomoko Ishii ◽  
Mayumi Takazawa ◽  
Hiroyasu Kato ◽  
Hiroyuki Sakamoto ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Chemical Composition ◽  
Mineral Composition ◽  
Blast Furnace Slag ◽  
Fine Powder ◽  
Cementitious Materials ◽  
Leaching Tests ◽  
Measured Concentration ◽  
Furnace Slag

A “realistic alteration model” is needed for various cementitious materials. Hypothetical settings of mineral composition calculated based on the chemical composition of cement, such as Atkins’s model, have been used to estimate the alteration of cementitious material. However, model estimates for the concentration of certain elements such as Al and S in leachate have been different from experimental values. In a previous study, we created settings for a mineralogical alteration model by taking the initial chemical composition of cementitious materials from analysis results in experiments and applying their ratios to certain hydrated cement minerals, then added settings for secondary generated minerals in order to account for Ca leaching. This study of alteration estimates for ordinary portland cement (OPC) in groundwater showed that the change in Al and S concentrations in simulated leachate approached values for actual leachate[1]. In the present study, we develop an appropriate mineral alteration model for blended cementitious materials and conduct batch-type leaching experiments that use crushed samples of blast furnace slag cement (BFSC), silica cement (SC), and fly ash cement (FAC). The cement blends in these experiments used OPC blended with blast furnace slag of 70 wt.%, silica cement consisting of an amorphous silica fine powder of 20 wt.%, and fly ash of 30 wt.%. De-ionized water was used as the leaching solution. The solid-liquid ratios in the leaching tests were varied in order to simulate the alteration process of cement hydrates. The compositions of leachate and minerals obtained from leaching tests were compared with those obtained from models using hypothetical settings of mineral composition. We also consider an alteration model that corresponds to the diversity of these materials. As a result of applying the conventional OPC model to blended cementitious materials, the estimated Al concentration in the aqueous solution was significantly different from the measured concentration. We therefore propose an improved model that takes better account of Al behavior by using a more reliable initial mineral model for Al concentration in the solution.

scholarly journals Fresh and Mechanical Properties of Self-Consolidating Concrete Incorporating Silica Fume and Metakaolin

2021 ◽  
Author(s):  
Syed Ahmed
Keyword(s):  
Mechanical Properties ◽  
Construction Industry ◽  
Silica Fume ◽  
High Flow ◽  
Self Consolidating Concrete ◽  
Supplementary Cementing Materials ◽  
The Past

Self-consolidating concrete (SCC) has been gaining greater interest over the past decades with its excellent offerings of efficiency, beauty, and savings. Due to its high flow ability, resistance to bleeding, and non-segregating properties, SCC holds tremendous potential for use in the construction industry. SCC requires no vibration and can fill capacities, including the ones with even the most congested reinforcements. Since SCC can be obtained by incorporating supplementary cementing materials (SCMs) such as silica fume and metakaolin. It is crucial to develop and test different SCC mixtures with different volumes of SCMs to evaluate fresh and mechanical properties. Although silica fume is used in the production of SCC, the use of metakaoline in SCC is new. In this project, eleven SCC mixtures having different volumes of silica fume and metakaolin are developed. In addition, the influence of the above mentioned pozzolans (silica fume and metakaolin) on the fresh and mechanical properties are analyzed. Recommendations on fresh and mechanical properties of silica fume and metakaoline based SCC mixtures are also provided.

Packing Density Improvement for Improving Strength of Cement Paste

2019 ◽  
Vol 943 ◽  
pp. 124-128 ◽  
Author(s):  
Jian Jian Chen ◽  
Hong Niao Chen ◽  
Gu Li
Keyword(s):  
Silica Fume ◽  
Packing Density ◽  
Water Film ◽  
High Strength ◽  
Cementitious Materials ◽  
Maximum Strength ◽  
Depth Analysis ◽  
Fuel Ash ◽  
Pulverized Fuel ◽  
Pulverized Fuel Ash

To design a mix for high-strength concrete is not easy, one of the methods is to improve the packing density of the cementitious materials. To study the effect of packing density on strength, a comprehensive research program using superfine pulverized fuel ash and silica fume was carried out. Results showed that a high superfine pulverized fuel ash and silica fume ratios could result in a lower optimum W/CM ratio for maximum strength. Depth analysis illustrated that the optimum water film thickness for maximum strength is always at around 0.01 to 0.05 μm, regardless of the SPFA and SF ratios.

Improvements on Mechanical Property and Microstructure of Cementitious Composite Incorporated with Silica Fume and Carbon Nanotube

2019 ◽  
Vol 298 ◽  
pp. 167-171
Author(s):  
Gu Yue Han ◽  
Jian Lin Luo
Keyword(s):  
Compressive Strength ◽  
Carbon Nanotube ◽  
Silica Fume ◽  
Cementitious Materials ◽  
Filler Loading ◽  
Cement Matrix ◽  
Ultrasonic Dispersion ◽  
Integrated Network ◽  
Positive Effects ◽  
Ultrafine Silica

Nano-size fillers (ultrafine silica fume (USF) or/and multi-walled carbon nanotube (MWCT)) were incorporated into cement matrix to fabricate nano-fillers reinforced cementitious materials (NFRCs) with surfactant ultrasonic dispersion and subsequently mix cast process. The flexural and compressive strengths of four groups NFRCs with varied nano-filler loading were comprehensively investigated. Results show, there are positive effects on the flexural and compressive strength of NFRCs with nano-fillers loading, especially when USF and MWCT are incorporated simultaneously, and the correspondent maximal flexural and compressive strength can increase by above 17%, 28% with respect to the baseline, respectively. The pozzolan infilling effect of USF and the crack-bridging effect of dispersed MWCT result in the dense and integrated network microstructures of cured NFRC.

scholarly journals The dissolution of simulant vitrified intermediate level nuclear waste in young cement water

MRS Advances ◽  
2020 ◽  
Vol 5 (3-4) ◽  
pp. 131-140
Author(s):  
Colleen Mann ◽  
Jeremy R. Eskelsen ◽  
Donovan N. Leonard ◽  
Eric Pierce ◽  
Claire L Corkhill
Keyword(s):  
Nuclear Waste ◽  
Alkaline Earth ◽  
Water Solution ◽  
Cementitious Materials ◽  
Intermediate Level ◽  
Short Term ◽  
Alkaline Earth Elements ◽  
Altered Layer ◽  
Safety Case ◽  
The Uk

AbstractIt is pertinent to the safety case for geological disposal in the UK that the behaviour of vitrified wastes in proximity to cementitious materials is understood. In this study, vitrified simulant intermediate level nuclear waste (ILW) was subject to dissolution in a synthetic cement water solution to simulate disposal conditions. Results show that the presence of alkali / alkaline earth elements in the cementitious solution can be favourable, at least in the short-term, leading to lower dissolution rates associated with incorporation of these elements into the altered layer of the glass.

Propolis and Commonly Used Intracanal Irrigants. Comparative Evaluation of Inflammatory Potential

2013 ◽  
Vol 37 (4) ◽  
pp. 373-376 ◽  
Author(s):  
M Jolly ◽  
N Singh ◽  
M Rathore ◽  
S Tandon ◽  
S Sharma
Keyword(s):  
Calcium Hydroxide ◽  
Optical Density ◽  
Saline Solution ◽  
Short Term ◽  
Model Method ◽  
Short Term Evaluation ◽  
Term Evaluation ◽  
Physiologic Saline ◽  
The Mean ◽  
Mean Optical Density

The present study evaluated the inflammatory/irritant potential of propolis in comparison with commonly used intracanal irrigants such as chlorhexidine and calcium hydroxide, with normal saline solution as control using an animal (Wistar rats) model. Method: 2% Evans blue was intravenously injected into the lateral caudal vein. 0.1 ml each of the test solutions was intradermally injected into the experimental sites designed on their shaved backs. The animals were then sacrificed after 1½ and 3 hours respectively. Each piece of skin containing the injected solution was excised, immersed in 4ml formamide and incubated at 45°C for 72 hours. After filtration with glass wool, optical density(OD) was measured using a spectro-photometer and analyzed statistically. Results: At 620 nm irrespective of time, the mean optical density with Calcium Hydroxide was found to be maximum (0.197±0.095) while that with DMSO Propolis was found to be minimum (0.070±0.016). Both at 90 min and 180 min, the mean optical density with Calcium Hydroxide was found to be maximum. Conclusions: On short term evaluation, maximum inflammation was seen with calcium hydroxide followed by chlorhexidine and DMSO extract of propolis. Minimum inflammation was seen with sterile physiologic saline. With progress of time, maximum inflammation was seen with calcium hydroxide followed by chlorhexidine and DMSO extract of propolis which was non-significant.

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