The feasibility of using electromagnetic waves in determining membrane failure through concrete

Concrete flat roof defects such as water leakage present a significant and common problem in large buildings, particularly in tropical countries, where rainfall is high. To monitor this condition, effective non-destructive test methods are required to detect problems at an early stage, especially hidden defects within the concrete roof, which are critical. This paper presents the potential use of electromagnetic (EM) waves for determining possible leakage of the concrete flat roof as a result of failure of the waterproof membrane layer. This study was assessed, experimentally by investigation of the propagation of EM waves through the roof and their interaction with water. Novel Microwave sensors described in the paper operate in the 6 GHz to 12 GHz frequency range using a Marconi 6200A microwave test set. A range of existing methods was reviewed and analysed. Results of experimental tests confirmed that microwaves could be used as an alternative non-destructive method for identifying water ingress caused by membrane failure into the concrete roof surface

Earth construction in Algeria between tradition and modernity

This paper was accepted for publication in the journal Proceedings of the Institution of Civil Engineers: Construction Materials and the definitive published version is available at http://dx.doi.org/10.1680/jcoma.15.00048.In the south of Algeria, many indigenous settlements have been built using local earth construction techniques; in the north, despite the availability of suitable earth, only a few rural contemporary settlements have been built using ‘improved’ earth construction. This paper adopts a case study approach to examine and compare structural deficiencies of two earth-built housing settlements in different regions in Algeria. In the indigenous earth settlement in the south, where adobe was used in combination with local timber and stones, the dwellings exhibit many structural defects. Stabilisation of the soil and introduction of modern materials in the contemporary rammed earth settlement in the north has not, however, helped produce structurally adequate dwellings. These dwellings also exhibited many cracks and debonding of rendering, and thus did not fulfil the requirements and aspirations of their occupants. The study concludes that for a potentially successful earth building scheme there are inter-related factors that should be considered: selection of an appropriate soil and construction technique, implementation of a suitable structural design, construction and post-completion processes, availability of relevant skills and provision of adequate training on the construction technique