An improved procedure for obtaining and maintaining well characterized partial water saturation states on concrete samples to be used for mass transport tests

A conditioning procedure is proposed allowing to install into the concrete specimens any selected value of water saturation degree with homogeneous moisture distribution. This is achieved within the least time and the minimum alteration of the concrete specimens. The protocol has the following steps: obtaining basic drying data at 50 °C (water absorption capacity and drying curves); unidirectional drying of the specimens at 50 °C until reaching the target saturation degree values; redistribution phase in closed containers at 50 °C (with measurement of the quasi-equilibrium relative humidities); storage into controlled environment chambers until and during mass transport tests, if necessary. A water transport model is used to derive transport parameters of the tested materials from the drying data, i.e., relative permeabilities and apparent water diffusion coefficients. The model also allows calculating moisture profiles during isothermal drying and redistribution phases, thus allowing optimization of the redistribution times for obtaining homogeneous moisture distributions.

Predicting water permeability in sedimentary rocks from capillary imbibition and pore structure

In this paper, absolute water permeability is estimated from capillary imbibition and pore structure for 15 sedimentary rock types. They present a wide range of petrographic characteristics that provide degrees of connectivity, porosities, pore size distributions, water absorption coefficients by capillarity and water permeabilities. A statistical analysis shows strong correlations among the petrophysical parameters of the studied rocks. Several fundamental properties are fitted into different linear and multiple expressions where water permeability is expressed as a generalized function of the properties. Some practical aspects of these correlations are highlighted in order to use capillary imbibition tests to estimate permeability. The permeability–porosity relation is discussed in the context of the influence of pore connectivity and wettability. As a consequence, we propose a generalized model for permeability that includes information about water fluid rate (water absorption coefficient by capillarity), water properties (density and viscosity), wetting (interfacial tension and contact angle) and pore structure (pore radius and porosity). Its application is examined in terms of the type of pores that contribute to water transport and wettability. The results indicate that the threshold pore radius, in which water percolates through rock, achieves the best description of the pore system. The proposed equation is compared against Carman–Kozeny's and Katz–Thompson's equations. The proposed equation achieves very accurate predictions of the water permeability in the range of 0.01 to 1000 mD.

Beyond megaprojects?. Water alternatives for mass tourism in coastal Mediterranean Spain

Water availability in adequate quantities and qualities is a fundamental requirement for tourism. In the Mediterranean, one of the world’s leading tourist destinations, water availability is subject to modest and erratic precipitation figures which may decline with climate change. The tourist industry therefore may have to assure future supplies by either recurring to new technologies such as desalination or increasing efficiency in water use. A third and yet little explored alternative would be to seek for complementary of uses with irrigation, the traditional user in many coastal Mediterranean areas and holder of substantial amounts of water. In this paper we present the example of the Consorcio de Aguas de la Marina Baja to show how Benidorm, in Mediterranean Spain and one of the most important tourist centers of the Mediterranean, obtains part of its water through agreements with farmers by which these trade their water with Benidorm and other towns’ treated wastewater of enough quality to be used for irrigation, and obtain several compensations in return. The advantages and disadvantages of the water trade between farmers and tourist interests in the Benidorm area are discussed and we argue that solutions to the pending water crisis of many coastal Mediterranean tourist areas may not need to rely uniquely on expensive technologies to generate new resources but may attempt other alternatives.