Abstract
This portfolio of work presents an investigation into the behaviour of a number of different pipe liner materials that can be used to improve the performance of the predominantly cast iron potable water supply infrastructure. A literature review was carried out, in order to clarify the most suitable directions for an experimental programme. Accordingly, two key strands of experimentation were developed. Firstly, the behaviour of unlined control, two interactive liners and one non-structural liner, the behaviour of liners under host-pipe failure was considered. This was done by initiating a controlled ring fracture in the host main, in order to assess the ability of the selected liners to withstand this event. Secondly, the response of a liner to a deformation that occurred after ring fracture was considered. This deformation was also carried out on some jointed sections of liner, to give an indication of total system performance. Alongside these investigations a series of material characterisation exercises were carried out, to determine the microstructure of the cast iron, its tensile properties and the creep performance of the polymer liner used in the second strand of the investigation. The response of unsupported liner sections to applied internal water pressure was also investigated. Both interactive liners survived the failure criterion applied in the first strand, whilst the non-structural liner, as expected, did not. A simple method was developed that allowed the bending moment-curvature relationship in a bend test to be modelled from tensile data; this gave satisfactory agreement with experimental data. In the second strand the liner was found to be able to withstand significant deformation (50 mm), for a substantial time period (two weeks) without apparent damage, the joints also seemed able to survive the application of deformations thought to be representative of the upper limit of those found in the UK. Both the observation that liners are able to withstand host-pipe fracture and the subsequent observation that they can withstand events that may occur afterwards are potentially significant to the UK water industry, offering a large number of potential benefits that may be environmental, economic or performance related.