Long-term performance of surface impregnation of reinforced concrete structures with silane

This is the author’s version of a work that was accepted for publication in the journal, Construction and Building Materials. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published at: http://dx.doi.org/10.1016/j.conbuildmat.2013.07.038Silanes can act as hydrophobic pore liners for reinforced concrete (RC) structures. They can significantly reduce the depth of chloride penetration, a major cause of steel reinforcement corrosion. However, there is little published information on their long-term performance. Thirty-two concrete cores were extracted from eight full-scale RC bridge supporting cross-beams that were treated with silane 20 years ago. Their water absorption by capillarity was measured and compared with sixteen control cores extracted from four non-silane treated RC cross-beams constructed at the same time. Results show that silanes may provide a residual protective effect against water even after 20 years of service

Influence of SCC on the effectiveness of controlled permeability formwork in improving properties of cover concrete

Controlled permeability formwork (CPF) is a system proven to enhance the durability of near-surface concrete significantly during the casting process. However, the use of CPF requires vibration energy to expel the excess water and air within the concrete mix. On the other hand, self-compacting concrete (SCC), as the name suggests, does not require any vibration effort for its compaction. As a result, the effectiveness of CPF to improve properties of the cover concrete in SCC couldbe different from that of the conventional concrete. Therefore, the influence of two types of SCC on the effectiveness of CPF was studied by comparing air permeability, sorptivity, water permeability and tensile strength of the cover concrete. Test results showed that compared to impermeable formwork (IF) the use of CPF improved the permeation properties of both conventional concrete and SCC mixes. The surface tensile strength also improved in both cases. The surface formed with CPF did not have any blowholes. Therefore, it is concluded that the use of CPF for manufacturing SCC could be recommended

Properties of fly ash concrete modified with hydrated lime and silica fume

This paper presents the results of an experimental investigation on the properties of fly ash concrete incorporating either hydrated lime or silica fume to improve the early strength of concrete. Test results indicated that the addition of lime and silica fume improved the early age compressive strength of fly ash concrete. The inclusion of silica fume was also found to increase the 28 days strength significantly. The air permeability of concrete containing lime and silica fume either decreased or remained almost the same when compared to the concrete without these. The addition of lime and silica fume also improved the sorptivity of concrete. Through the use of differential scanning calorimetry and thermogravimetric analysis (DSC/TG), it was demonstrated that the addition of hydrated lime increased the Ca(OH)2 content; whereas the addition of silica fume decreased the Ca(OH)2 content in the cement paste. The mercury intrusion porosimetry (MIP) data confirmed the beneficial action of hydrated lime and silica fume, towards decreasing the total pore volume of fly ash cement paste. © 2009 Elsevier Ltd. All rights reserved

Performance of silane impregnants for the protection of reinforced concrete

Silanes can act as hydrophobic pore liners for reinforced concrete (RC) structures. They can significantly reduce the depth of chloride penetration, a major cause of steel reinforcement corrosion. There is little published information however, on their long-term performance. For this study, 32 concrete cores were extracted from eight full-scale RC bridge supporting cross-beams which had been treated with silane 20 years ago. Their rate of water absorption by capillarity was measured and compared with 16 control cores extracted from four non-silane treated RC cross-beams constructed at the same time. Results show that these silanes provide a residual protective effect against water even after 20 years of service. The performance of silane impregnations on concrete incorporating blended cements, and the effects of different formwork, ages of concrete and curing conditions prior to impregnation were also investigated. Concrete specimens were cast with CEM III/A (Portland cement with 50% ground granulated blast furnace slag) cement. The performance of the silane impregnation was assessed by the rate of water absorption due to capillary action. The results indicate that improvements in performance were identified within the sample groups of lower w/c ratios, steel finishes, outside curing and double coatings of silane treatment. The findings from both research programmes indicate that silane impregnations can provide a significant reduction to the water absorption characteristics of both site retrieved and laboratory cast concrete samples. It was observed that performance was reduced with increasing the age of the silane impregnation service life. In addition, silane impregnations applied at specimens with plywood or tampered finish demonstrated a greater reduction on water absorption than specimens with a steel finish

Correction to: Polymer Nanocomposites in Biomedical Engineering

In the original version of the book, the following belated corrections have been incorporated: The co-editor names ''Basheer Ahmed'' has been changed to ''M. Basheer Ahamed'' and ''Al-Maadeed Mariam Ali S A'' has been changed to ''Mariam Ali S A Al-Maadeed''. In chapter ''Silver Nanoparticles and Its Polymer Nanocomposites Synthesis, Optimization, Biomedical Usage, and Its Various Applications'', the author name ''Snehal Kargirwar Bramhe'' has been changed to ''Snehal Kargirwar Brahme'' and the affiliations of authors ''Snehal Kargirwar Brahme'' and ''Subhash Kondawar'' were swapped. The correction book has been updated with the changes.Scopu