Influence of the slice position on chloride migration tests for concrete in marine conditions

Chloride migration tests are used to measure the concrete capacity to inhibit chloride attack. Many researchers carry out this test in a slice of concrete extracted from the central part of cylindrical specimens, discarding about 75% of the concrete used to mold the specimens. This fact generated the question: would it be possible to extract more slices from a same specimen without losing the confidence in the results? The main purpose of this work is to answer this question. Moreover, another aim of this study was to show the difference of chloride penetration between finished faces and the formwork surfaces of concrete beams and slabs. The results indicated that it is possible to use more slices of a single specimen for a chloride migration test. Moreover, it was demonstrated that there is a significant difference of chloride penetration between the finished surface and the formwork surface of the specimens.     

Merging ICT and informal transport in Jakarta's ojek system

This paper discusses how information and communication technologies (ICT) may influence travel behavior of an informal transport system, and whether and in which ways merging digital technologies represents disruption for a specific sociotechnical ensemble. For decades, ojek has been a form of informal passenger transport, based on motorcycles in Jakarta, and recently smartphone apps have become available in that sociotechnical arrangement. We randomly surveyed passengers and drivers in the central district, for both those who do and do not use these apps. Despite many similarities between both groups, the drivers who use smartphones for their trips reported higher daily incomes, longer average trip distances and a larger coverage area. Passengers using conventional ojek transport reported lower levels of both safety perception and satisfaction when compared to app-based ojek users. For both categories of user, ojek seems to compete with, complement, and be an alternative to bus rapid transit and the suburban rail system (KRL) in the area covered by our sample. The areas covered by regular buses and vans roughly match the origins and destinations of ojek trips.