HYDROLOGICAL IMPACT OF EXPANDED CLAY MATERIAL INTRODUCED IN DIFFERENT SUDS: A LABORATORY-BASED ASSESSMENT

The philosophy of conventional urban drainage has been, for many decades, to convey runoff far away from the city center by using pipes and other subsurface methods, and therefore, giving rainfall a negative connotation, being concealed from the surface. Sustainable Urban Drainage Systems (SUDS) changed this paradigm by valuing water as a vital resource which improves our life whilst controlling floods, reducing diffuse pollution and enabling the reuse of runoff after being treated through their structures, amongst other benefits such as biodiversity and amenity. There are many

possible materials that could be used as part of SUDS structures, depending upon the intended function.

METHODOLOGY

HYDRAULIC TEST THERMAL TEST EVAPORATION TEST

RESULTS AND DISCUSSIONS

Three replicates of this design were used to determine the infiltration capacity of

different materials: expanded clay, limestone aggregate and blast furnace slag. The system has a 20 cm sub-base layer, geotextile, 5 cm base and a top

surface. The runoff simulation was carriedout with different intensities (267, 321 and

375 mm/h). Total of 27 trials of 40 min.

A box-platform with three layers of expanded clay and limestone aggregate of

different granulometries is used. The sides of the systems are thermally insulated and heat

flow is applied to the bottom. A stainless steel plate is used to homogenize the heat

transfer and temperature sensors are placed at different depths. Data is collected for 48

hours during the test period.

To determine the influence of the expanded clay on evaporation, 9 devices are prepared,

consisting of a 20 cm sub-base and a 5 cm base layer. Three different systems are

made: Terram 1000 geotextile, DanofeltPY150 geotextile and without geotextile.

The data were collected during the 21 days of the test with initial saturation condition

and identical environmental conditions.

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Sin Geotextil Geotextil Tenam 1000 Geotextil Danofelt PY150

Delay in the appearance of peak flow up to 7-8 minutes from the start and reduction of

maximum flow rates during the flood.

CONCLUSIONS REFERENCES

Carlos Costales Campa, Felipe P. Álvarez Rabanal, Dr. Luis Á. Sañudo Fontaneda,

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Expanded clay L Limestone Aggregate 20-40 mm Limestone aggregate 4-8 mm

Weight loss (kg)Thermal transmittance (W/m2·K)Runoff infiltration (L/m2)

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ARLITA CALIZA ESCORIA DE ALTO HORNO

Low thermal transmittance is equivalent to less heat flowing through the material and will

therefore act better as an insulator.

Terram 1000 geotextile further reduces evaporation. The presence of expanded clay

will delay evaporation over time.

The expanded clay introduced into the subbase layer significantly influences the infiltration rates. Its presence delays the peak flow period by almost two minutes compared to the other materials

tested, in addition to reducing surface runoff thanks to its hydraulic capabilities. From the thermal point of view, expanded clay has much higher insulation characteristics than other materials commonly used

in this type of drainage system, so it is considered to have a very interesting potential for use as a construction element that allows the

accumulation of thermal energy.

• Flores Moras, M.A. y Rodríguez Hernández, J. (2014). “Construcción delaparcamiento de firmes permeables de la guía, Gijón”. Univ. Cantabria.

• Sañudo Fontaneda, L.A., Castro Fresno, D., Rodríguez Hernández, J. (2014).“Análisis de la infiltración de agua de lluvia en firmes permeables con superficiesde adoquines y aglomerados porosos para el control en origen de inundaciones”.Univ. de Cantabria.

• Sañudo Fontaneda, L.A., Andrés Valeri, V. C., Costales Campa, C., CadenasFernández, F. (2018) “The long-term hydrological performance of permeablepavement systems in northern Spain: An approach to the ‘End-of-life’ concept”.Polytechnic School of Mieres, University of Oviedo, Spain.