Durability Improvement of Concrete in the Environment of Compound Salt and Freeze-Thaw Cycles by Incorporating Mineral Additives

2011 ◽  
Vol 477 ◽  
pp. 30-36 ◽  
Author(s):  
Ming Yu Hu ◽  
Jin Sheng Peng ◽  
Cheng Ping Ding ◽  
Jian Yi Chen
Keyword(s):  
Fly Ash ◽  
Orthogonal Array ◽  
Dominant Role ◽  
Complex Environments ◽  
Freeze Thaw ◽  
Chloride Sulfate ◽  
Mineral Additives ◽  
Durability Of Concrete ◽  
Array Testing

Durability improvement of concrete in the complex environments of chloride, sulfate and freeze-thaw, by incorporating compound mineral additives of fly ash, slag, diatomite and zeolite in concrete, was studied through the approach of orthogonal array testing and related analysis. The results show that zeolite and diatomite play a dominant role in improving the durability of concrete in the complex environments, but the role of fly ash and slag should not be ignored. A reasonable combination of the mineral additives can effectively improve the durability of concrete in the complex conditions without lowering or even increasing the early and later strength of concrete.

Study on the Influence of Freeze-Thaw on the Carbonation Property of Fly Ash Concrete

2013 ◽  
Vol 357-360 ◽  
pp. 939-943 ◽  
Author(s):  
Jian Gang Niu ◽  
Liang Yan ◽  
Hai Tao Zhai
Keyword(s):  
Fly Ash ◽  
Laboratory Simulation ◽  
Influence Coefficient ◽  
Carbonation Depth ◽  
Freeze Thaw ◽  
Fly Ash Concrete ◽  
Concrete Carbonation ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

Based on the coupling testing program of freeze-thaw and carbonation, the laboratory simulation test is carried out. The laws of carbonation depth of the fly ash concrete suffered the freeze-thaw cycle in different test modes and the influence of fly ash dosage on concrete carbonation depth after the freeze-thaw cycle are studied. Defining the influence coefficient of the freeze-thaw cycles on carbonation depth of concrete, the mechanism of coupling of freeze-thaw and carbonation is analyzed,and the role of freeze-thaw and carbonation in the coupling process are obtained.

Effect of silica fume on durability of concrete composites containing fly ash

2013 ◽  
Vol 20 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Peng Zhang ◽  
Qing-fu Li
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Shrinkage Strain ◽  
Carbonation Depth ◽  
Freeze Thaw ◽  
Slump Flow ◽  
Carbonation Resistance ◽  
Dry Shrinkage ◽  
Shrinkage Property ◽  
Durability Of Concrete

AbstractIn this paper, the effect of silica fume on the workability and durability of concrete composites containing fly ash, including water impermeability, dry shrinkage property, carbonation resistance and freeze-thaw resistance, are presented. Four different silica fume contents (3%, 6%, 9% and 12%) were used. The results indicate that the addition of silica fume has greatly improved the durability of water impermeability, the carbonation resistance and the freeze-thaw resistance of the concrete composites containing fly ash. With the increase in silica fume content, the length of water permeability and the carbonation depth of the specimens decrease gradually, and the relative dynamic elastic modulus of the specimens has a tendency to increase. However, the addition of silica fume has a little adverse effect on the workability and dry shrinkage property of concrete composites containing fly ash. With the increase in silica fume content, both the slump and the slump flow decrease gradually, and the dry shrinkage strain increases gradually.

Effect of fly ash on freeze–thaw durability of concrete in marine environment

2018 ◽  
Vol 19 (2) ◽  
pp. 146-161 ◽  
Author(s):  
Md. M. Islam ◽  
Mohammad Tarequl Alam ◽  
Md. S. Islam
Keyword(s):  
Fly Ash ◽  
Marine Environment ◽  
Freeze Thaw ◽  
Durability Of Concrete

scholarly journals Freeze-Thaw Resistance of Cement Screed with Various Supplementary Cementitious Materials

2019 ◽  
Vol 58 (1) ◽  
pp. 66-74 ◽  
Author(s):  
Pavel Reiterman ◽  
Ondřej Holčapek ◽  
Ondřej Zobal ◽  
Martin Keppert
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Frost Resistance ◽  
Blast Furnace Slag ◽  
Ceramic Powder ◽  
Supplementary Cementitious Materials ◽  
Partial Replacement ◽  
Freeze Thaw ◽  
Mineral Additives ◽  
Furnace Slag

Abstract This paper describes a study of the effect of partial replacement of ordinary Portland cement (OPC) by various mineral additives in the screed mixtures. Ceramic powder, blast furnace slag and fly ash were gradually employed in increments of 12.5 wt.% up to 50 wt.% to replace OPC. The mixtures were designed to a constant consistency. The influence of mineral additives was evaluated in terms of the air content in the fresh mixtures, the compressive strength, the flexural strength and the freeze-thaw resistance and using non-destructive measurements after 28 and 90 days. The accompanied paste sampleswere analysed using thermogravimetry to monitor the hydration process by means of total bound water content. The decrease in the mechanical properties and the frost resistance of the mixtures with the mineral additives were recorded, because of the necessity for a larger addition of water. According to the valid standards for concrete screed related to the frost resistance, it could be concluded that maximal suitable cement replacement contents are 12.5, 37.5 and 50 wt.% for ceramic powder, fly ash and blast furnace slag, respectively. The freeze-thaw resistance of the studied materials was found to be strongly related to the content of CSH and CAH hydrates.

scholarly journals Study of Durability of Concrete with Fly Ash as Fine Aggregate under Alternative Interactions of Freeze-Thaw and Carbonation

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Mingjie Mao ◽  
Dongsheng Zhang ◽  
Qiuning Yang ◽  
Wenbo Zhang
Keyword(s):  
Fly Ash ◽  
Concrete Strength ◽  
Microstructural Analysis ◽  
Fine Aggregate ◽  
X Ray Diffraction ◽  
Carbonation Depth ◽  
Freeze Thaw ◽  
Water To Cement Ratio ◽  
Deterioration Mechanism ◽  
Durability Of Concrete

To study the durability of concrete with fly ash as fine aggregate subjected to alternative attacks of freeze-thaw and carbonation, the appearance, mass loss, relative dynamic modulus of elasticity, relative compressive strength, and carbonation depth of the concrete are investigated using cyclic tests under single carbonation, single freeze-thaw, and alternation of freeze-thaw and carbonation. In addition, microstructural analysis techniques including scanning electron microscope and X-ray diffraction are adopted to reveal the deterioration mechanism of alternating freeze-thaw and carbonation. Results show that carbonation is beneficial for refining the pore structure and increasing concrete strength in the initial alternative cycle, which delays the damage from freeze-thaw cycles. Damage from freeze-thaw causes crack propagation in concrete, which leads to carbonation intensification. Compared with other test modes, concrete under alternative freeze-thaw and carbonation causes the greatest degree of deterioration during the initial freeze-thaw cycles. The carbonation depth under alternative freeze-thaw and carbonation is positively correlated with the carbonation time and the water-to-cement ratio. However, as the reactant is continuously consumed due to the expansion of crystalline ice and CaCO3, alternative cycles result in the appearance of many more new cracks in the concrete.

Chronic Pain: Fundamental Scientific Considerations, Specifically for Legal Claims

2013 ◽  
Vol 18 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Robert J. Barth
Keyword(s):  
Health Outcomes ◽  
Pain Perception ◽  
Driving Forces ◽  
Psychological Treatment ◽  
Dominant Role ◽  
Meta Analysis ◽  
General Medicine ◽  
Pain Syndrome ◽  
Problematic Relationship

Abstract Scientific findings have indicated that psychological and social factors are the driving forces behind most chronic benign pain presentations, especially in a claim context, and are relevant to at least three of the AMA Guides publications: AMA Guides to Evaluation of Disease and Injury Causation, AMA Guides to Work Ability and Return to Work, and AMA Guides to the Evaluation of Permanent Impairment. The author reviews and summarizes studies that have identified the dominant role of financial, psychological, and other non–general medicine factors in patients who report low back pain. For example, one meta-analysis found that compensation results in an increase in pain perception and a reduction in the ability to benefit from medical and psychological treatment. Other studies have found a correlation between the level of compensation and health outcomes (greater compensation is associated with worse outcomes), and legal systems that discourage compensation for pain produce better health outcomes. One study found that, among persons with carpal tunnel syndrome, claimants had worse outcomes than nonclaimants despite receiving more treatment; another examined the problematic relationship between complex regional pain syndrome (CRPS) and compensation and found that cases of CRPS are dominated by legal claims, a disparity that highlights the dominant role of compensation. Workers’ compensation claimants are almost never evaluated for personality disorders or mental illness. The article concludes with recommendations that evaluators can consider in individual cases.

НЕКОТОРЫЕ ОСОБЕННОСТИ РАСПРОСТРАНЕННОСТИ РЕСПИРАТОРНОЙ АЛЛЕРГИИ НА ЮГЕ РОССИИ

2019 ◽  
Author(s):  
D.Sh. Macharadze
Keyword(s):  
Dominant Role ◽  
Pollen Allergy ◽  
Respiratory Allergy ◽  
House Dust Mites ◽  
Dust Mites ◽  
The Past ◽  
Regional Features ◽  
Respiratory Allergies ◽  
Southern Russia

В обзорной статье приведены данные по распространенности респираторной аллергии - аллергического ринита и бронхиальной астмы на юге России, опубликованные за последние десятилетия. Показана доминирующая роль пыльцевой аллергии практически во всем южном регионе России. В Чеченской Республике у больных респираторной аллергией обнаружена сходная частота встречаемости сенсибилизации к клещам домашней пыли и пыльце злаковых трав (51,1 и 52,5 соответственно), тогда как сенсибилизация к пыльце амброзии и полыни встречалась в 3 раза реже (26,6 и 20,7 соответственно) по сравнению с соседними регионами юга России. Эти данные демонстрируют климатогеографические, экологические и другие региональные особенности в распространении респираторной аллергии.The review article presents data on the prevalence of respiratory allergy - allergic rhinitis and bronchial asthma in southern Russia, published over the past decades. The dominant role of pollen allergy is shown in almost the entire southern region of Russia. In the Chechen Republic, sensitization to house dust mites and grass pollen was found in patients with respiratory allergy equally (51.1 and 52.5, respectively), whereas ragweed and mugwort sensitization was 3 times less (26.6 and 20.7, respectively) compared with the neighboring regions of southern Russia. These data demonstrate climate-geographical, environmental and other regional features in the prevalence of respiratory allergies.

KEGAGALAN PRIVATISASI BUMN DI ERA REZIM ORDE BARU DALAM PERSPEKTIF EKONOMI POLITIK

Wacana Publik ◽  
2019 ◽  
Vol 12 (02) ◽  
Author(s):  
Syamsul Ma'arif
Keyword(s):  
Market Economy ◽  
Free Market ◽  
Dominant Role ◽  
The State ◽  
Early Years ◽  
New Order ◽  
Free Market Economy ◽  
Economic Sectors ◽  
Role Of The State

After had being carried out nationalization and hostility against west countries, the New Order regime made important decision to change Indonesia economic direction from etatism system to free market economy. A set of policies were taken in order private sector could play major role in economic. However, when another economic sectors were reformed substantially, effords to reform the State Owned Enterprises had failed. The State Owned Enterprise, in fact, remained to play dominant role like early years of guided democracy era. Role of the State Owned Enterprises was more and more powerfull). The main problem of reforms finally lied on reality that vested interest of bureaucrats (civil or military) was so large that could’nt been overcome. 

Conclusion

2018 ◽  
Author(s):  
Ildar Garipzanov
Keyword(s):  
Cultural History ◽  
Middle Ages ◽  
Late Antiquity ◽  
Western Europe ◽  
Dominant Role ◽  
Ninth Century ◽  
Sources Of Authority ◽  
History Of ◽  
Historical Periods

The concluding chapter highlights how the cultural history of graphic signs of authority in late antiquity and the early Middle Ages encapsulated the profound transformation of political culture in the Mediterranean and Europe from approximately the fourth to ninth centuries. It also reflects on the transcendent sources of authority in these historical periods, and the role of graphic signs in highlighting this connection. Finally, it warns that, despite the apparent dominant role of the sign of the cross and cruciform graphic devices in providing access to transcendent protection and support in ninth-century Western Europe, some people could still employ alternative graphic signs deriving from older occult traditions in their recourse to transcendent powers.

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