Journal Published Online: 26 June 2019
Volume 43, Issue 3

A Device for the Simultaneous Determination of the Water Retention Properties and the Hydraulic Conductivity Function of an Unsaturated Coarse Material; Application to a Green-Roof Volcanic Substrate

CODEN: GTJODJ

Abstract

The determination of the water retention curve (WRC) and hydraulic conductivity function (HCF) of a specific volcanic coarse granular material used as a substrate for urban green roofs in Europe was carried out on a newly developed specific device in which low suctions, typical of coarse granular materials, were controlled. Smaller suctions (up to 32 kPa) were imposed by using a hanging column system, and larger suctions (between 32 and 50 kPa) were imposed by using the axis translation technique in the same cell. The changes in suction during the tests were monitored by using a high accuracy differential pressure transducer. They were also used to determine the HCF by means of both Kunze and Kirkham’s and Gardner’s methods. The former technique was used at low suctions (<4 kPa) to account for the impedance effects due to the high air entry value ceramic porous disk and the latter was used between 4 and 50 kPa. Good comparability was observed in the data from both methods, demonstrating the good performance of the device. The mathematical expressions of the WRC of van Genuchten and Brooks and Corey were used, and a good fitting with our experimental data was obtained. Conversely, the HCFs derived from these expressions appeared to lead to a significant underestimation, confirming the need of an operational and simple device for the experimental determination of the HCF. Also, this material proved to be an appropriate material for green urban infrastructures, because of its lightweight, satisfactory water retention capability and hydraulic conductivity.

Author Information

Stanić, Filip
Ecole des Ponts ParisTech, Navier/CERMES, Marne-la-Vallée, Cedex 2, France Ecole des Ponts ParisTech, HM&Co, Marne-la-Vallée, Cedex 2, France
Cui, Yu-Jun
Ecole des Ponts ParisTech, Navier/CERMES, Marne-la-Vallée, Cedex 2, France
Delage, Pierre
Ecole des Ponts ParisTech, Marne-la-Vallée, France
De Laure, Emmanuel
Ecole des Ponts ParisTech, Navier/CERMES, Marne-la-Vallée, Cedex 2, France
Versini, Pierre-Antoine
Ecole des Ponts ParisTech, HM&Co, Marne-la-Vallée, Cedex 2, France
Schertzer, Daniel
Ecole des Ponts ParisTech, HM&Co, Marne-la-Vallée, Cedex 2, France
Tchiguirinskaia, Ioulia
Ecole des Ponts ParisTech, HM&Co, Marne-la-Vallée, Cedex 2, France
Pages: 18
Price: $25.00
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Details
Stock #: GTJ20170443
ISSN: 0149-6115
DOI: 10.1520/GTJ20170443