Abstract:ABSTRACT:The effect of strontium aluminate (SrAl 2 O 4 ) on the hydration process of a calcium sulphoaluminate (C 4 A 3 Ŝ ) cement was investigated. Cement pastes were prepared by mixing C 4 A 3 Ŝ , hemihydrate (CaSO 4 ·½H 2 O, CŜ H 0.5 ) and 0, 10 or 20wt% of SrAl 2 O 4 (SrA). The amount of CŜ H 0.5 was 15, 20 or 25wt% based on the C 4 A 3 Ŝ quantity. The cement pastes were hydrated using water to cement ratios (w/c) of 0.4 and 0.5. Samples were cured from 1 to 28 d. The compressive strength and setting time … Show more
“…Nano WMTA also consists of elements such as strontium salt and carbonate and zeolite, which are stabilizer agents (16, 17). Furthermore, scanning electron microscopic analysis of strontium aluminate in combination with gypsum showed that this component can reduce the size of ettringite, which in turn could decrease the void size between ettringite needlelike crystals (34). These findings are also consistent with previously published investigations (18, 20).…”
Introduction
The aim of this study was to evaluate the impact of radiopaque additive, bismuth oxide, particle size on the physical properties, and radiopacity of tricalcium silicate–based cements.
Methods
Six types of tricalcium silicate cement (CSC) including CSC without bismuth oxide, CSC + 10% (wt%) regular bismuth oxide (particle size 10 μm), CSC + 20% regular bismuth oxide (simulating white mineral trioxide aggregate [WMTA]) as a control, CSC + 10% nano bismuth oxide (particle size 50–80 nm), CSC + 20% nano-size bismuth oxide, and nano WMTA (a nano modification of WMTA comprising nanoparticles in the range of 40–100 nm) were prepared. Twenty-four samples from each group were divided into 4 groups and subjected to push-out, surface microhardness, radiopacity, and compressive strength tests. Data were analyzed by 1-way analysis of variance with the post hoc Tukey test.
Results
The push-out and compressive strength of CSC without bismuth oxide and CSC with 10% and 20% nano bismuth oxide were significantly higher than CSC with 10% or 20% regular bismuth oxide (P < .05). The surface micro-hardness of CSC without bismuth oxide and CSC with 10% regular bismuth oxide had the lowest values (P < .05). The lowest radiopacity values were seen in CSC without bismuth oxide and CSC with 10% nano bismuth oxide (P < .05). Nano WMTA samples showed the highest values for all tested properties (P < .05) except for radiopacity.
Conclusions
The addition of 20% nano bismuth oxide enhanced the physical properties of CSC without any significant changes in radiopacity. Regular particle-size bismuth oxide reduced the physical properties of CSC material for tested parameters.
“…Nano WMTA also consists of elements such as strontium salt and carbonate and zeolite, which are stabilizer agents (16, 17). Furthermore, scanning electron microscopic analysis of strontium aluminate in combination with gypsum showed that this component can reduce the size of ettringite, which in turn could decrease the void size between ettringite needlelike crystals (34). These findings are also consistent with previously published investigations (18, 20).…”
Introduction
The aim of this study was to evaluate the impact of radiopaque additive, bismuth oxide, particle size on the physical properties, and radiopacity of tricalcium silicate–based cements.
Methods
Six types of tricalcium silicate cement (CSC) including CSC without bismuth oxide, CSC + 10% (wt%) regular bismuth oxide (particle size 10 μm), CSC + 20% regular bismuth oxide (simulating white mineral trioxide aggregate [WMTA]) as a control, CSC + 10% nano bismuth oxide (particle size 50–80 nm), CSC + 20% nano-size bismuth oxide, and nano WMTA (a nano modification of WMTA comprising nanoparticles in the range of 40–100 nm) were prepared. Twenty-four samples from each group were divided into 4 groups and subjected to push-out, surface microhardness, radiopacity, and compressive strength tests. Data were analyzed by 1-way analysis of variance with the post hoc Tukey test.
Results
The push-out and compressive strength of CSC without bismuth oxide and CSC with 10% and 20% nano bismuth oxide were significantly higher than CSC with 10% or 20% regular bismuth oxide (P < .05). The surface micro-hardness of CSC without bismuth oxide and CSC with 10% regular bismuth oxide had the lowest values (P < .05). The lowest radiopacity values were seen in CSC without bismuth oxide and CSC with 10% nano bismuth oxide (P < .05). Nano WMTA samples showed the highest values for all tested properties (P < .05) except for radiopacity.
Conclusions
The addition of 20% nano bismuth oxide enhanced the physical properties of CSC without any significant changes in radiopacity. Regular particle-size bismuth oxide reduced the physical properties of CSC material for tested parameters.
“…This may be due to the generation of hydrogen gas under radiation, and the partial reaction of calcium sulphoaluminate particles with surrounding formed strontium aluminate. In these cement blocks ettringite is detected as smaller but needle shaped crystals; the presence of SrAl 2 O 4 inhibits the formation of ettringite crystals [33]. Also, as a result of carbonation, the cement blocks may undergo changes in the porosity of cement blocks.…”
Section: A-scanning Electron Microscopy (Sem)mentioning
confidence: 99%
“…Carbonation of cement blocks results from the reactions of (C 3 S) and (C 2 S) with Carbon Dioxide. These reactions result in formation of CaCO 3 and silica gel, as follows [21,33]: There is a shift in the basal spacing of the cement. This can be attributed to the energy transferred from the gamma rays to the molecules of water and the cement components.…”
Section: A-scanning Electron Microscopy (Sem)mentioning
Cement is an important material in radioactive waste management. It is used as a solidifying agent for the concentrated wastes resulting from the treatment process. The solidification process results in immobilized wastes. To protect the human and the environment for long periods of time, the solidified waste forms should withstand the operation and storage conditions. Hence, the cement blocks should have proper mechanical and chemical properties. Moreover, the effect of radiation on the blocks should be studied to assure the retention of radionuclides by the cement matrix under radiation fields. To carry out the study, cement blocks were irradiated by Gamma radiation at doses 40, 120 and 240 KGy. The morphology of the blocks was studied before and after irradiation using X-ray Diffraction Patterns (XRD), and Scanning Electron Microscopy (SEM). The results of morphology studies are presented. The morphology studies indicated an improvement in the fixation of radionuclides on the cement matrix after irradiation.
“…No obstante su empleo cada vez en crecimiento en las obras civiles ha demandado que se realicen estudios más detallados los cuales tienen como fin, entender el efecto de añadir el compuesto de aluminato de estroncio co-dopado con Eu,Dy (SrAl 2 O 4 :M, donde M=Eu 2+ , Dy 3+ .) en mezclas a base de Cemento Portland Ordinario (CPO) ( Velazco et al 2014) .…”
Section: Introductionunclassified
“…El artículo tiene como finalidad profundizar en el entendimiento del comportamiento físico y de las propiedades mecánicas de los compuestos cementantes fotoluminiscentes; así como también, analizar la influencia del SrAl 2 O 4 :M como parte de mezclas basadas en CPO a nivel macroscópico para su aplicación en la in-geniería civil. Se debe recalcar que el estudio a nivel físico-químico, atómico y molecular ha sido ya realizado en otras investigaciones anteriores (Ptáček et al, 2014;Velazco et al, 2014;Ptacek, 2014).…”
Hoy en día, la necesidad de desarrollar materiales que fomenten el ahorro de energía eléctrica de manera eficiente ha sido uno de los temas trascendentales estudiados alrededor del mundo. Con esta primicia, la presente investigación determinó que la inclusión de Aluminato de Estroncio co-dopado con Europio y Disprosio en mezclas a base de Cemento Portland; noolo produce el fenómeno de fotoluminiscencia, sino que mejora también sus propiedades mecánicas, mediante la realizacióne diversas pruebas de laboratorio físico-mecánicas como la resistencia a compresión en probetas, además de análisisuímicos con XRF en distintas muestras de mortero. La investigación encontró además que la proporciones 0.3:1 del compuesto/beneficio de aplicar el compuesto cementante fotoluminiscente comoseñalética vial a largo plazo es mucho más rentable que el empleo de la luminaria convencional.
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