Analysis of the weld strength of the High Density Polyethylene (HDPE) dam liner

An analysis was carried out to determine the strength of welded joints in High Density Polyethylene (HDPE) dam liners. Samples were collected of welded joints and subjected to tensile tests and creep test. It was observed that the welded joints from field welded samples were much weaker and had a very low straining capacity than the un-welded material. The field welded specimens registered average strengths of 5 MPa as compared to 12 MPa of un-welded specimens and a maximum strain at fracture of 0.5 as compared to 3.5 of un-welded specimens. As a result of the weak welds it was found necessary to conduct further research into the best welds possible and a protocol for hot air and hot knife welding was developed. It was shown that for hot air welding while holding the width of the weld, applied pressure and dwell time of the pressure constant at 2.6cm, 0.3 MPa and 60 s, the recommended temperature of the hot air to achieve the strongest weld was 176 and for hot knife welding the recommended temperature of the knife was 400°C

Rural structures in the tropics: Design and development

There is a growing awareness of the need for better rural structures and services in many developing countries. Here the FAO presents an up-to-date, comprehensive text focusing on structures for small- to medium-scale farms and, to some extent, village-scale agricultural infrastructure. The book will help to improve teaching on the subject of rural buildings in the tropics and will assist professionals engaged in providing technical advice. Importantly, it also provides guidance in the context of disaster recovery and rehabilitation, for rebuilding the sound rural structures and related services that are key to development and economic sustainability