Concrete in a drying environment inevitably experiences shrinkage arising from the physical and chemical loss of water. In this project, a comparative study was undertaken to investigate the drying shrinkage characteristics of concrete under different reinforcing regimes. Six types of reinforced concrete specimens were studied, comprising plain concrete and specimens which were reinforced with conventional steel mesh, steel fibres and a new concept involving steel rings. Hooked Dramix steel fibres used were used in three different ways, namely by conventional random distribution, by aligning using a machine and by aligning by hand on a horizontal layer of choice. Drying shrinkage of the concrete was measured for 90 days following a 28-day period of curing. It emerged that samples with machine aligned steel fibres and hand aligned steel rings performed as well as randomly aligned fibre samples, within the normal variations in such tests. These categories of reinforcement significantly out-performed conventional mesh and plain concrete, as expected. This conclusion will support the recent research into aligned fibre concrete, where significant ductility improvement in flexure has been established. It has now been shown that these improvements in flexure are not at the expense of a reduction in shrinkage performance.
展开▼
