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This Paper reports an experimental investigation to establish the influence of ambient CO2, concentration, exposure temperature and curing duration on the rate of carbonation in concrete. The test specimens were concrete cylinders 100 mm in diameter and 200 mm high. Of the parameters investigated, the standard 28-day compressive strength f28 was found to be effectively representative of the concrete quality in several carbonation models proposed. Index test results, i.e. water absorption and sorptivity, were also incorporated to depict the effects of the surface property of concrete. The proposed models agreed well with the experimental data.

A closed-loop servo-controlled hydraulic testing machine can be used to generate experimentally the complete stress–strain curves for concrete in compression. However, the deformation readings obtained from the built-in low-voltage displacement transducers or other transducers placed between the machine platens include not only deformations of the concrete but also those due to machine flexibility and end-restraint of the specimen. In this paper, a correction factor is proposed to account for these effects. This requires the use of a compressometer fixed directly to the test specimen and transducers placed between the machine platens. More realistic stress–strain curves for concrete with cylinder (100 × 200mm) compressive strengths of up to 130 MPa have thus been obtained for the entire loading range.

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To optimize learning in lectures, students need to maintain a sustained level of attention to the lecture material. Previous research has suggested, however, that student attention declines over the course of the lecture. One strategy suggested to improve sustained attention of students during the lecture is to encourage note-taking by students. The provision of partial notes, where parts of the lecture slide materials are removed, has been associated with improved academic outcomes of students. Few studies, however, have directly compared the effects of partial notes on student attention with the provision of complete notes or no notes at all. This study investigated the effects of the provision of these three types of lecture notes on note quality through the lecture, a proxy measure of sustained attention, and on subsequent short-term factual retention of the lecture material. In total, 41 students were randomly assigned to one of the three notes groups. They listened to a lecture while taking notes and then completed a multiple-choice quiz. Their notes were evaluated for note quality. No advantage of using partial notes was found on the measures of sustained attention or on the results of the multiple-choice quiz, contrary to previous findings. Student sustained attention did degrade over the course of the lecture; this degradation occurred for all note type groups. This study suggests that educators within the higher education system reconsider the use of partial notes in lectures.

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