Study on Sulfate-Attack of Slag-Based Geopolymer Concrete

2011 ◽  
Vol 261-263 ◽  
pp. 142-146
Author(s):  
Qing Wang ◽  
Zhao Yang Ding ◽  
Lin Li ◽  
Jing Da ◽  
Zhi Tong Sui
Keyword(s):  
Mass Loss ◽  
Water Glass ◽  
Linear Expansion ◽  
Mass Loss Rate ◽  
Expansion Rate ◽  
Geopolymer Concrete ◽  
Commercial Applications ◽  
Resistance Performance ◽  
Better Than

Geopolymer has been attracted world attention as a potentially revolutionary material that is one of the ideal substitutes of portland cement. Fundamental studies on geopolymer are increasing rapidly because of its potential commercial applications. However, little work has been done on its erosion resistance of sulfate. In this paper, slag and metakaolin as source materials, different modules of water-glass as activator were used to prepare slag-based geopolymer which was then prepared to make slag-based geopolymer concrete. Linear expansion rate and mass loss of concrete were used as indicators to explore different erosion rules of slag-based geopolymer concrete which was long-term immersed in the 5% ( by mass ) Na2SO4 solution. Comparative experiments were also done between slag-based geopolymer concrete and ordinary cement concrete. The results showed that geopolymer concrete had excellent sulfate resistance performance, linear expansion rate and mass loss rate of geopolymer were 0.024% and 0.58% respectively at the soaking age of 49d as the water glass modulus was 1.4 and the water-glass content was 4%. It was also found that the anti-sulfate ability of geopolymer concrete is much better than that of ordinary concrete with the same strength grade.

scholarly journals Link between Mass-loss and Variability Type for AGB Stars?

1999 ◽  
Vol 191 ◽  
pp. 395-400 ◽  
Author(s):  
Željko Ivezić ◽  
Gillian R. Knapp
Keyword(s):  
Mass Loss ◽  
Time Scales ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Dust Emission ◽  
Agb Stars ◽  
Similar Time ◽  
Color Distribution ◽  
K 12

We find that AGB stars separate in the 25–12 vs. 12-K color-color diagram according to their chemistry (O, S vs. C) and variability type (Miras vs. SRb/Lb). While discrimination according to the chemical composition is not surprising, the separation of Miras from SRb/Lb variables is unexpected.We show that “standard” steady-state radiatively driven models provide excellent fits to the color distribution of Miras of all chemical types. However, these models are incapable of explaining the dust emission from O-rich SRb/Lb stars. The models can be altered to fit the data by postulating different optical properties for silicate grains, or by assuming that the dust temperature at the inner envelope radius is significantly lower (300–400 K) than typical condensation temperatures (800–1000 K), a possibility which is also supported by the detailed characteristics of LRS data. While such lower temperatures are required only for O- and S-rich SRb/Lb stars, they are also consistent with the colors of C-rich SRb/Lb stars.The absence of hot dust for SRb/Lb stars can be interpreted as a recent (order of 100 yr) decrease in the mass-loss rate. The distribution of O-rich SRb/Lb stars in the 25–12 vs. K-12 color-color diagram shows that the mass-loss rate probably resumes again, on similar time scales. It cannot be ruled out that the mass-loss rate is changing periodically on such time scales, implying that the stars might oscillate between the Mira and SRb/Lb phases during their AGB evolution as proposed by Kerschbaum et al. (1996). Such a possibility appears to be supported by recent HST images of the Egg Nebula obtained by Sahai et al. (1997), the discovery of multiple CO winds reported by Knapp et al. (1998), and long-term visual light-curve changes detected for some stars by Mattei (1998).

scholarly journals Decay of a long-term monitored glacier: Careser Glacier (Ortles-Cevedale, European Alps)

2013 ◽  
Vol 7 (6) ◽  
pp. 1819-1838 ◽  
Author(s):  
L. Carturan ◽  
C. Baroni ◽  
M. Becker ◽  
A. Bellin ◽  
O. Cainelli ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Mass Loss Rate ◽  
Regional Scale ◽  
European Alps ◽  
Systematic Observation ◽  
Average Mass ◽  
Observation Series ◽  
The 19Th Century

Abstract. The continuation of valuable, long-term glacier observation series is threatened by the accelerated mass loss which currently affects a large portion of so-called "benchmark" glaciers. In this work we present the evolution of the Careser Glacier, from the beginning of systematic observation at the end of the 19th century to its current condition in 2012. In addition to having one of the longest and richest observation records among the Italian glaciers, Careser is unique in the Italian Alps for its 46 yr mass balance series that started in 1967. In the present study, variations in the length, area and volume of the glacier since 1897 are examined, updating and validating the series of direct mass balance observations and adding to the mass balance record into the past using the geodetic method. The glacier is currently strongly out of balance and in rapid decay; its average mass loss rate over the last 3 decades was 1.5 m water equivalent per year, increasing to 2.0 m water equivalent per year in the last decade. Although these rates are not representative at a regional scale, year-to-year variations in mass balance show an unexpected increase in correlation with other glaciers in the Alps, during the last 3 decades. If mass loss continues at this pace, the glacier will disappear within a few decades, putting an end to this unique observation series.

scholarly journals iPTF14hls as a variable hyper-wind from a very massive star

2019 ◽  
Author(s):  
Takashi J Moriya ◽  
Paolo A Mazzali ◽  
Elena Pian
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Variable Mass ◽  
Stellar Winds ◽  
Spectral Evolution ◽  
Extreme Wind ◽  
Sudden Outburst ◽  
Bright Phase

Abstract The origin of iPTF14hls, which had Type IIP supernova-like spectra but kept bright for almost two years with little spectral evolution, is still unclear. We here propose that iPTF14hls was not a sudden outburst like supernovae but rather a long-term outflow similar to stellar winds. The properties of iPTF14hls, which are at odds with a supernova scenario, become natural when interpreted as a stellar wind with variable mass-loss rate. Based on the wind hypothesis, we estimate the mass-loss rates of iPTF14hls in the bright phase. We find that the instantaneous mass-loss rate of iPTF14hls during the 2-year bright phase was more than a few M⊙ yr−1 (“hyper-wind”) and it reached as much as 10 M⊙ yr−1 . The total mass lost over two years was about 10 M⊙. Interestingly, we find that the light curve of iPTF14hls has a very similar shape to that of η Carinae during the Great Eruption, which also experienced a similar but less extreme brightening accompanied by extraordinary mass loss, shedding more than 10 M⊙ in 10 years. The progenitor of iPTF14hls is less than 150 M⊙ if it still exists, which is similar to η Carinae. The two phenomena may be related to a continuum-driven extreme wind from very massive stars.

scholarly journals Long-term evolution of AGB wind envelopes: Insights from hydrodynamical models

1999 ◽  
Vol 191 ◽  
pp. 379-388
Author(s):  
M. Steffen ◽  
D. Schönberner ◽  
R. Szczerba
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Alternative Mechanism ◽  
Agb Stars ◽  
Hydrodynamical Simulations ◽  
Thermal Pulses

Up to now, hydrodynamical models of dust-driven AGB winds do not generally take into account the ‘long-term’ changes of the stellar parameters (on stellar evolution time scales of 103 to 105 yrs), although it is well known that the luminosity and (very likely) the mass loss rate undergo significant variations when so called ‘thermal pulses’ occur on the upper AGB. In this review we demonstrate that time-dependent radiation hydrodynamics calculations are needed to understand the formation, structure, and spectral energy distribution of detached dust shells detected by IRAS and ISO. Combined with appropriate models, these observations can reveal part of the previous mass loss history on the AGB and allow an empirical check of presently adopted mass loss laws.Based on insights from hydrodynamical simulations, we discuss the two competing scenarios that have been put forward to explain the origin of the very thin molecular shells recently discovered around some carbon stars. We find that the signature of a short mass loss ‘eruption’ broadens quickly with time due to the related velocity gradient across the shell. Hence, this scenario is not considered a likely explanation of detached CO shells. On the other hand, the alternative mechanism, interaction of winds, is shown to be capable of producing very thin shells of greatly enhanced gas density in the dusty outflows from AGB stars by sweeping up matter at the interface between both type of winds.

scholarly journals Decay of a long-term monitored glacier: the Careser glacier (Ortles-Cevedale, European Alps)

2013 ◽  
Vol 7 (4) ◽  
pp. 3293-3335 ◽  
Author(s):  
L. Carturan ◽  
C. Baroni ◽  
M. Becker ◽  
A. Bellin ◽  
O. Cainelli ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
European Alps ◽  
Systematic Observation ◽  
Average Mass ◽  
Observation Series ◽  
Area And Volume

Abstract. The continuation of valuable, long-term glacier observation series is threatened by the accelerated mass loss which currently affects a large portion of so-called "benchmark" glaciers. In this work we present the evolution of the Careser glacier, from the beginning of systematic observation at the end of the nineteenth century to its current condition in 2012. In addition to having one of the longest and richest observation record among the Italian glaciers, Careser is unique in the Italian Alps for its 45 yr mass balance series started in 1967. In the present study, variations in the length, area and volume of the glacier since 1897 are examined, updating the series of direct mass balance observations and extending it into the past using the geodetic method. The glacier is currently strongly out of balance and in rapid decay; its average mass loss rate over the last three decades was −1.5 m water equivalent per year, increasing to −2.0 m water equivalent per year in the last decade. If mass loss continues at this pace, the glacier will disappear within a few decades, putting an end to this unique observation series.

Experimental Study of Sulfate Attack Resistance Performance on Cement Concrete Pavement

2014 ◽  
Vol 505-506 ◽  
pp. 270-273 ◽  
Author(s):  
Ji Feng Liang ◽  
Chao Zhang ◽  
Xin Yu Fang Wang
Keyword(s):  
Fly Ash ◽  
Mass Loss Rate ◽  
Immersion Test ◽  
Sulfate Attack ◽  
Concrete Pavement ◽  
Cement Concrete ◽  
Fly Ash Concrete ◽  
Cement Concrete Pavement ◽  
Resistance Performance

Airport concrete pavement in high latitude northwest area attacked by sulfate of different extent, which influence early strength and ultimate strength of cement concrete. In this paper, the double doped silica fume and fly ash concrete have been made long-term immersion test research. From the mass loss rate, compressive strength and flexural strength, effect on the corrosion resistance are studied with fly ash, silicon ash adding in a composite Portland cement. Methods to improve the performance of sulfate attack resistance are obtained by experiment.

Water accumulation as a function of temperature on specimens in an electron microscope cold stage

1986 ◽  
Vol 44 ◽  
pp. 114-115 ◽  
Author(s):  
M.K. Lamvik ◽  
D.A. Kopf ◽  
S.D. Davilla ◽  
J.D. Robertson
Keyword(s):  
Electron Microscope ◽  
Mass Loss ◽  
Liquid Helium ◽  
Liquid Nitrogen ◽  
Liquid Nitrogen Temperature ◽  
Liquid Helium Temperature ◽  
Helium Temperature ◽  
Cold Stage ◽  
Water Accumulation ◽  
Better Than

Last year we reported1 that there is a striking reduction in the rate of mass loss when a specimen is observed at liquid helium temperature. It is important to determine whether liquid helium temperature is significantly better than liquid nitrogen temperature. This requires a good understanding of mass loss effects in cold stages around 100K.

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