scholarly journals Alkali–silica reaction (ASR)—performance testing: Influence of specimen pre-treatment, exposure conditions and prism size on concrete porosity, moisture state and transport properties

2013 ◽  
Vol 53 ◽  
pp. 145-167 ◽  
Author(s):  
Jan Lindgård ◽  
Erik J. Sellevold ◽  
Michael D.A. Thomas ◽  
Bård Pedersen ◽  
Harald Justnes ◽  
...  
2013 ◽  
Vol 53 ◽  
pp. 68-90 ◽  
Author(s):  
Jan Lindgård ◽  
Michael D.A. Thomas ◽  
Erik J. Sellevold ◽  
Bård Pedersen ◽  
Özge Andiç-Çakır ◽  
...  

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2625 ◽  
Author(s):  
Miguel Barreto Santos ◽  
Jorge De Brito ◽  
António Santos Silva

Alkali-silica reaction (ASR) is one of the major degradation causes of concrete. This highly deleterious reaction has aroused the attention of researchers, in order to develop methodologies for its prevention and mitigation, but despite the efforts made, there is still no efficient cure to control its expansive consequences. The incorporation of recycled aggregates in concrete raises several ASR issues, mainly due to the difficult control of the source concrete reactivity level and the lack of knowledge on ASR’s evolution in new recycled aggregate concrete. This paper reviews several research works on ASR in concrete with recycled aggregates, and the main findings are presented in order to contribute to the knowledge and discussion of ASR in recycled aggregate concrete. It has been observed that age, exposure conditions, crushing and the heterogeneity source can influence the alkalis and reactive silica contents in the recycled aggregates. The use of low contents of highly reactive recycled aggregates as a replacement for natural aggregates can be done without an increase in expansion of concrete. ASR expansion tests and ASR mitigation measures need to be further researched to incorporate a higher content of recycled aggregates.


2017 ◽  
Vol 18 (4) ◽  
pp. 528-538 ◽  
Author(s):  
Colin Giebson ◽  
Katja Voland ◽  
Horst-Michael Ludwig ◽  
Birgit Meng

Author(s):  
Y.M Rao ◽  
Adukondalu Devandla ◽  
Shravan Kumar Yamsani

Many drug substances interact with each other and affect the CYP enzyme system and transport properties of other drugs.  The present study was aimed to investigate the effect of ketoconazole and rifampicin pre-treatment on the transport of carbamazepine across the intestine in rats. The transport of carbamazepine across different parts of intestine was studied by the everted and non-everted sac methods. The control and ketoconazole (80 mg/kg) and rifampicin (60 mg/kg) pre-treated rats were sacrificed and the intestine was harvested. The sacs of intestine were   prepared, treated with carbamazepine solution and then placed in Dulbecco’s buffer. Samples were collected periodically and the drug content was estimated using HPLC method. The results show that there was a significant (p<0.05) difference in the transport of carbamazepine from the intestinal sacs of pretreated with ketoconazole and rifampicin as compared to control. It appears that ketoconazole and rifampicin may affect the intestinal transport of carbamazepine and hence may result in pharmacokinetic interactions.  


2022 ◽  
Vol 151 ◽  
pp. 106641
Author(s):  
Krishna Siva Teja Chopperla ◽  
Thano Drimalas ◽  
Mengesha Beyene ◽  
Jussara Tanesi ◽  
Kevin Folliard ◽  
...  

2018 ◽  
Vol 163 ◽  
pp. 05009
Author(s):  
Daria Jóźwiak-Niedźwiedzka ◽  
Mariusz Dąbrowski ◽  
Karolina Gibas ◽  
Aneta Antolik ◽  
Michał A. Glinicki

Salt solutions are used to ensure safe driving conditions during winter. NaCl deicer is the most often used brine in Polish climatic zone. The chemical effects of this type of chloride-based deicer in wetting and drying (WD) and temperature cycles on concrete need to be better understood. This research was focus to study the microstructure of air-entrained pavement concrete after combined chemical (10% of NaCl) and physical (WD and 60°C) exposure conditions. The adopted WD and temperature regime was designed to verify the hypothesis that regularly alternating wetting and drying cycles with external alkali supply from deicer salt will provoke the Alkali-Silica Reaction (ASR). The aggregates varied their origin and mineralogical composition. The microscopic examination was carried out on concrete specimens using SEM with EDX. The microscopic analysis has shown that main reason for concrete deterioration during cyclic chemical and physical exposure conditions was both physical influence - WD cycles and the chemical influence – ASR (primarily, the fine aggregate which lead to form of alkali-silica gel). The expansive gel was shown to be capable of destroying the test specimens. Also differences in mineralogical composition of coarse aggregates influenced on the concrete prism expansion due to ASR.


Desalination ◽  
2006 ◽  
Vol 200 (1-3) ◽  
pp. 645-647 ◽  
Author(s):  
Vasco Silva ◽  
Valter Silva ◽  
Adélio Mendes ◽  
Luis Madeira ◽  
Suzana Nunes

1988 ◽  
Vol 102 ◽  
pp. 165-174
Author(s):  
C. de Michelis

AbstractImpurities being an important concern in tokamaks, spectroscopy plays a key role in their understanding. Techniques for the evaluation of concentrations, power losses and transport properties are surveyed, and a few developments are outlined.


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