Influence of testing on permeability of compacted fine soils

The British standard constant-head triaxial test for measuring the permeability of fine-grained soils takes a relatively long time. A quicker test could provide savings to the construction industry, particularly for checking the quality of landfill clay liners. An accelerated permeability test has been developed, but the method often underestimates the permeability values compared owing to structural changes in the soil sample. This paper reports on an investigation
into the accelerated test to discover if the changes can be limited by using a revised procedure. The accelerated test is assessed and compared with the standard test and a ramp-accelerated permeability test. Four different finegrained materials are compacted at various water contents to produce analogous samples for testing using the three different methods. Fabric analysis is carried out on specimens derived from post-test samples using mercury intrusion porosimetry and scanning electron microscopy to assess the effects of testing on soil structure. The results show that accelerated testing in general underestimates permeability compared with values derived from the standard test, owing to changes in soil structure caused by testing. The ramp-accelerated test is shown to provide an improvement in terms of these structural changes.

Stress, eustress and the National Student Survey

The aim was to explore the relationship between sources of stress and a range of coping behaviours on student
satisfaction and motivation. Most research exploring sources of stress construes stress as distress, with little
attempt to consider positive, good stress or ‘eustress’ experiences. A cohort of first-year psychology students (N=88)
were surveyed on a range of stressors. These were amended from the UK National Student Survey (NSS, 2011).
Published university league tables draw heavily on student course satisfaction but study results suggest there was
also merit in measuring students’ intellectual motivation and the extent to which they felt part of a learning
community. Using multiple regression analyses, it was found that even the attributes that normally help one to adjust to change, such as self-efficacy, do little to help the new student adjust to university life, such was the acuteness of perceived stress in the first year. Social opportunities within the university were important to help new students integrate into university life and to help them network and build support. Educators need to consider how course experiences contribute, not just to potential distress but to potential eustress.