1,721,098 research outputs found
Metodi di prova non distruttivi per la valutazione della reattività alcali-silice di conglomerati cementizi
No full textAUTHOR BOOK TALK
Full text linkTim M. Berra: Wallace\u27s Acceptance of Darwin\u27s Priority in His Own Wordshttps://digitalcommons.rockefeller.edu/posters/1191/thumbnail.jp
New approach for assessing the potential alkali expansivity of slowly reactive siliceous aggregates in concrete
No full textThe combination of a petrographic analysis with the ASTM C1260-94 mortar-bar expansion test in a 1 M NaOH solution at 80°C and the current standard concrete prism expansion test at 38°C and 100% relative humidity (RH) appears to be the best guidance for evaluating the potential alkali reactivity of siliceous aggregates. To ascertain the reliability of this test methodology, concrete prism expansion tests are performed both in accordance with the standard test procedure and by varying the alkali content of the concrete in the range 2.3 to 9.0 kg Na 2O eq/m 3 of concrete. Based on the results, a modification of the test methodology is suggested for better evaluating the potential alkali reactivity of slowly expanding aggregates
Reazione alcali-silice nel calcestruzzo: valutazione del livello di soglia degli alcali mediante la misura del coefficiente di disordine dell’aggregato
No full textCorrosione delle armature in calcestruzzo. Prevenzione mediante rivestimenti a base di malta cementizia modificata con polimeri,
No full textAlkali-silica reactivity criteria for concrete aggregates
No full textIn this study, the suitability of the threshold alkali level, TAL, the kinetic parameter, In k, and the microstructural disorder coefficient, Cd, of the aggregates, taken as alkali-silica reactivity criteria, was assessed using different typologies of Italian natural ASR-susceptible aggregates of known field performance. The TAL, In k, and Cd were determined using a modified version of the RILEM AAR-3 concrete prism expansion test, the ASTM C1260 mortar-bar expansion test, and the infrared spectroscopy test, respectively. It was found that the three reactivity criteria are all appropriate for discriminating between reactive and innocuous aggregates. However, the TAL proves to be a more suitable criterion for interpreting the field performance data of the aggregates investigated. There exists a linear relationship between TAL and In k, or between TAL and Cd, which provides a rapid means of estimating the threshold alkali levels of ASR-susceptible aggregates from the results of the ultra-accelerated mortar-bar test and/or the infrared spectroscopy test. A TAL-based classification of the degree of reactivity of the aggregates, as well as some modifications of the reactivity domains established by the infrared spectroscopy method are also proposed. 1359-5997 © 2004 RILEM. All rights reserved
Corrosion prevention in reinforced concrete structures by means of polymer modified cementitious mortars
No full textUne nouvelle méthodologie de qualification des granulats silicieux vis-à-vis de l'alcalis-réaction dans le béton.
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