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Experimental procedures such as ASTM C1585, “Standard Test Method for Measurement of Rate of Absorption of Water by Hydraulic-Cement Concretes,” and ISO12572 have been recently developed to determine the rate of moisture transmission through hydrated cement systems. However, these methods do not provide an actual transport parameter that can be used in chloride ingress models to predict the service-life of concrete structures. This study focused on the development a reliable method to measure the nonlinear moisture diffusivity of concrete. The approach is based on the analysis of drying and wetting experiments performed with concrete samples of different thicknesses. The transport parameter is obtained by using Richards’ water transport model to analyze the mass variations measured during the tests. The method was tested over a wide range of different concrete mixtures produced with different water/cement ratios. Results indicate that the nonlinear function used to reproduce the mass variation curves must exhibit a strong increase for high water content values. The water diffusivity equation derived from this analysis allows reproducing the behavior of concrete during both the drying and absorption experiments using the same water transport model.

Construction time overrun is one of the common inefficiencies of public construction projects in Ethiopia. Laws and standard construction contracts stipulate different legal remedies against project time overrun. This paper is meant to unravel these legal remedies and their application to construction project time overrun in public construction projects in Ethiopia. To this end, the magnitude of time overrun, its common causes, and the practical implementation of legal remedies against it is exposed through literature review, primary data obtained from 18 roads and 10 public building projects, and interviews of 10 key informants. The result showed, although time is not the essence of construction contract in international standard conditions of contracts, it is a fundamental obligation the breach of which would give rise to termination of the contract under the laws and standard conditions of contracts applicable to public works in Ethiopia. However, the paper established that the practical implantation of these legal remedies against time overrun in public construction projects is very erratic although time overrun is a rampant challenge of the construction industry of the country in general and public construction projects in particular.