Development of a Model for Stormwater Runoff Prediction on Vertical Test Panels Coated with Plaster and Mortar

Abstract

Leaching outdoor tests (LOT) are commonly used to assess the leaching of substances from construction materials. In this context, the amount of stormwater in contact with the surface material is of special interest for analyzing the runoff loads of substances from building façades. A numerical model was developed in MATLAB on the basis of previous analytical models to calculate the collected stormwater runoff volumes from the vertical test panels (VTP) during LOT. In the model, wind-driven rain (WDR) is considered to be the main mechanism for determining the amount of water impinging on the VTP, so it is a crucial factor in the modeling for the façade runoff. The new model makes it possible to simulate the runoff volumes from VTP that are covered with a wide variety of plaster and mortar. Using the new model, it was possible to relate the VTP runoff volumes obtained during an 18-month sampling period for LOTs performed at the Fraunhofer Institute for Building Physics in Valley, Germany. When comparing the simulation results with the field test accumulated runoffs, the model exhibited a difference of no more than 3.5% for each of the analyzed materials. The simulation results are satisfying, and the paper demonstrates the feasibility of the modelling approach for the runoff assessment of VTP covered with a variety of plaster and mortar.

Entwicklung eines Modells zur Bewertung der Umwelteigenschaften üblicher Putze und Mörtel

“…-Wie können die unter Realbedingungen an einer mit einem bestimmten Produkt beschichten Fassade anfallenden und für Auslaugprozesse zur Verfügung stehenden Wassermengen rechnerisch abgebildet werden? -Ist eine Modellierung der stattfindenden Stofffreisetzung nicht nur durch mathematische Funktionen, Bild 1 Vertikale Probekörper mit jeweils 0,5 m 2 Fläche im Freilandversuch [4].…”

“…Für den Vormauermörtel (exemplarisch) betrug die in den Freilandversuchen nach 315 Tagen ermittelte kumulierte Abflussmenge 65,3 l, während das Fassadenabflussmodell für dasselbe Material 63,1 l als kumuliertes Abfluss ergebnis ergab. Der Tag mit dem höchsten gesammel-Gegenüberstellung von rechnerisch ermittelten und experimentell erhaltenen Abflussvolumina am Beispiel eines Vormauermörtels [4].Comparison of cumulative simulated and actual runoff volumes for the example of a facing masonry mortar[4].Quelle: P. Vega-Garcia/Fraunhofer IBP…”

Environmental Impact of Construction Products on Aquatic Systems—Principles of an Integrated Source–Path–Target Concept

“…Vega-Garcia et al [55] successfully applied a dynamic leaching model using the geochemical software PhreeQC [52,53] to describe the leaching of selected metals and sulfate for plasters and mortars in the field. In this example, the results of leaching tests, mineralogical composition and runoff data derived from a model are needed as input parameters [56]. The emissions of inorganic substances from concrete on a smaller scale can be described by functions derived from outdoor data by multiple regression.…”