Implementation of rainwater infiltration measurements in hygrothermal modelling of non-insulated brick cavity walls

The watertightness of solid masonry walls is generally based on the concept of buffering and afterwards drying out the absorbed rainwater. In cavity walls, on the contrary, the air layer provides a capillary break between the inner and outer leafs allowing drainage of rainwater and preventing infiltration to the interior wall surface. For assessing moisture-related risks, heat, air and moisture models have proven to be a valuable tool, but in the case of cavity walls two problems arise: the degree of water infiltration into the cavity is unknown, and no consensus is available on the method that should be used to implement these infiltrations in a simulation. For example, for the existing buildings, it is worthwhile to investigate whether injecting cavity wall insulation induces an increase or decrease in moisture-related pathologies, in contrast to adopting a fixed performance criterion for assessment. However, to complete a thorough analysis of a brick cavity wall, it is first useful to review the hygrothermal behaviour of cavity walls as it has been previously described in the literature. As such, this article provides a summary of experimental water infiltration results for cavity walls as described in the literature, discusses experimental results of four test walls subjected to four test protocols and extracts from these results the water infiltration rate for implementation in heat, air and moisture models. Finally, several methods for implementing the infiltrations in heat, air and moisture simulations are presented and evaluated based on different damage criteria. In general, the new modelling approaches are considered to provide realistic results. Nonetheless, an in situ investigation on whether mortar bridges occur in the cavity due to poor workmanship remains crucial to understanding the hygrothermal response as mortar bridges are found to have a dominant impact on the risk of mould growth at the interior wall surface.

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Sensitivity analysis of the hygrothermal behaviour of homogeneous masonry constructions: Interior insulation, rainwater infiltration and hydrophobic treatment

Journal of Building Physics ◽

10.1177/17442591211009937 ◽

2021 ◽

Vol 44 (6) ◽

pp. 510-538

Author(s):

Klaas Calle ◽

Nathan Van Den Bossche

Keyword(s):

Infiltration Rate ◽

Frost Damage ◽

Water Infiltration ◽

Sensitivity Analyses ◽

Mould Growth ◽

Damage Potential ◽

Interior Surface ◽

High Dependency ◽

The Impact ◽

Damage Criteria

Historical masonry constructions are difficult to mimic in hygrothermal models. The material properties of the walls are often highly uncertain due to the natural origin of the aggregates and the various, manual production processes used through time. Therefore, sensitivity analyses based on probabilistic simulations are powerful tools to indicate the risks on damage in masonry constructions. Damage criteria for relevant pathologies such as frost damage, potential decay of wooden beam heads and mould growth at the interior surface are used. The assessment methods (Scatter plots, Classification trees and Sobol indices) are based on 1D Heat, Air and Moisture simulations, including realistic variations on climate parameters and wall properties. These methodologies are applied to probabilistic simulations in which a potential damage risk is expected in historic masonries. The application of interior insulation, the use of hydrophobic treatments, and the impact of potential water infiltrations through cracks are discussed. In most of these situations a high dependency of each of the damage criteria on the rain intensity, the trend of the moisture retention/liquid conductivity curve and the absorption coefficient is evident, but also additional insights are found. For example, the thermal impact of interior insulation is negligible compared to its reduction of the first phase drying potential towards the interior. For hydrophobic treatments, the risk for damage typically decreases, but in combination with a rain water infiltration rate above approximately 5% of the wind driven rain the risk on mould growth at the interior surface significantly increases.

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Infiltração de água e resistência do solo à penetração em sistemas de cultivos integrados e em área de pastagem degradada

Colloquium Agrariae ◽

10.5747/ca.2020.v16.n5.a397 ◽

2020 ◽

Vol 16 (5) ◽

pp. 82-95

Author(s):

Leonnardo Cruvinel Furquim ◽

Epitácio José de Souza ◽

Nelmício Furtado da Silva ◽

Daniel Noe Coaguila Nuñez ◽

Juliana Silva Rodrigues Cabral ◽

...

Keyword(s):

Infiltration Rate ◽

Water Infiltration ◽

Integration System ◽

Double Ring ◽

Degraded Pasture ◽

Pasture Area ◽

Stocking Rates ◽

Resistance To Penetration ◽

Degraded Pastures

The objective of this study was to quantify water infiltration and resistance to penetration in a Latossolo Vermelho Distrófico (Typic Haplustox) cultivated with different land use systems and in a degraded pasture area. The studied areas are located in Rio Verde, state of Goiás (Brazil), where seven treatments were evaluated: T1 -Degraded; T2 -Fertilized pasture; T3 -Conventional; T4 -Crop-forest integrationsystem(CFI); T5 -Livestock-forest integrationsystem(LFI); T6 -crop-livestock-forest integration system (CLFI -hay); and T7 -crop-livestock-forest integration system (CLFI-silage). The water infiltration speed curves and the respective basic infiltration rate (BIR) values for the areas under study were determined. The infiltration of water into the soil was determined “in situ” by the double ring infiltrometer method and empirically through models proposed by Kostiakov and Kostiakov-Lewis. The soil resistance to penetration, up to a depth of 0.3 m, was performed using an impact penetrometer. The greatest infiltration in relation to time occurred in treatment T7. The highest values of BIR occurred in treatment T5. The model proposed by Kostiakov showed greater adjustment to the infiltration speed data obtained in the field. The lower resistance of the soil to penetration is provided by the diversity of species in the T4 treatment. The different management systems for recovering degraded pastures influenced the soil quality indicators studied, but there is a need for further studies to adjust the stocking rates in integrated systems in order not to return to the degradation scenario.

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In situ investigation of the primary recrystallization of alpha titanium in HVEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100110313 ◽

1978 ◽

Vol 36 (1) ◽

pp. 634-635

Author(s):

S. Naka ◽

R. Penelle ◽

R. Valle

Keyword(s):

Dimensional Analysis ◽

Texture Evolution ◽

Cold Work ◽

Three Dimensional ◽

Primary Recrystallization ◽

Thin Foils ◽

In Situ Investigation ◽

Grain Growth Model ◽

Alpha Titanium

The in situ experimentation technique in HVEM seems to be particularly suitable to clarify the processes involved in recrystallization. The material under investigation was unidirectionally cold-rolled titanium of commercial purity. The problem was approached in two different ways. The three-dimensional analysis of textures was used to describe the texture evolution during the primary recrystallization. Observations of bulk-annealed specimens or thin foils annealed in the microscope were also made in order to provide information concerning the mechanisms involved in the formation of new grains. In contrast to the already published work on titanium, this investigation takes into consideration different values of the cold-work ratio, the temperature and the annealing time.Two different models are commonly used to explain the recrystallization textures i.e. the selective grain growth model (Beck) or the oriented nucleation model (Burgers). The three-dimensional analysis of both the rolling and recrystallization textures was performed to identify the mechanismsl involved in the recrystallization of titanium.

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