Knowledge gaps regarding the hygrothermal and long-term performance of aerogel-based coating mortars

Karim, Ali; Johansson, Pär; Kalagasidis, Angela Sasic

doi:10.1016/j.conbuildmat.2021.125602

Cited by 15 publications

(20 citation statements)

References 66 publications

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“…Aerogel-based coating mortars (ACMs), plasters, and renders are a class of thermal insulation coating mortars with thermal conductivities around 30–50 mW/(m·K) [ 1 ]. This range also applies for conventional thermal insulation materials while it is more than 10 times lower than for conventional coating mortars.…”

Section: Introductionmentioning

confidence: 99%

“…Because of their superior thermal insulation properties, ACMs provide new technical solutions for the energy retrofitting of uninsulated building envelopes, particularly in listed and culturally valuable masonry buildings [ 1 , 2 , 3 ]. For many of the listed buildings, restrictions related to the preservation of character-defining elements, admissible thickness of building envelopes, and existing (moisture-related) damage to the construction, reduce the number of possible retrofitting measures [ 1 , 4 ]. In such cases, the application of ACMs can result in increased energy efficiency and slimmer wall elements with moderate changes to the façades.…”

Section: Introductionmentioning

confidence: 99%

“…In a recent literature review we conducted [ 1 ], the state of the art of the research on ACMs was presented with the aim of identifying the existing knowledge gaps in the hygrothermal performance of ACMs. Information on ACMs was collected based on a search of the Scopus databases, Web of Science, and Google Scholar.…”

Section: Introductionmentioning

confidence: 99%

“…Reliable data on the long-term performance of ACMs in real-life applications is necessary to assess the risks and plan measures to avoid moisture-related damage in buildings. Furthermore, the relatively higher material and application cost for ACMs must be justified [ 1 ]. The material cost of a commercial ACM was declared to be around 32 €/m 2 /cm in 2020, i.e., multiple times higher than the same for conventional mortars.…”

Section: Introductionmentioning

confidence: 99%

“…The material cost of a commercial ACM was declared to be around 32 €/m 2 /cm in 2020, i.e., multiple times higher than the same for conventional mortars. A more in-depth review of the cost versus performance ratio of ACMs was reported in [ 1 ].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Increasing Water Absorptivity of an Aerogel-Based Coating Mortar in Subsequent Wetting and Drying

Karim

Johansson

Kalagasidis

2022

Gels

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Aerogel-based coating mortars are energy-efficient composites with thermal conductivities of 30–50 mW/(m·K). They are useful when retrofitting uninsulated building envelopes, particularly in listed masonry buildings, as shown in studies. Meanwhile, the long-term reliability of their hygrothermal properties, typically declared after a single laboratory measurement, is not confirmed. To illustrate the latter and by combining experimental and numerical methods, this study shows that (1) the capillary water absorptivity of a commercially available aerogel-based coating mortar increases after repeated drying and wetting cycles, and (2) leads to a higher moisture content in a masonry wall. After the third cycle, the measured water absorption was more than five times higher than after the first one. Based on numerical simulations, the increasing capillary water absorptivity results in 36% higher relative humidity in the wall if the aerogel-based coating mortar is applied externally and exposed to driving rain. Future research should investigate the reasons behind the observed deviations in the capillary water absorptivity and whether it applies to other types of aerogel-based coating mortars.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Increasing Water Absorptivity of an Aerogel-Based Coating Mortar in Subsequent Wetting and Drying

Karim

Johansson

Kalagasidis

2022

Gels

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Determination of the Effective Thermal Conductivity of Aerogel-Based Coating Mortars Using Numerical Simulations—Random Packing

Karim,

Hagentoft

2023

Environmental Science and Engineering

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Aerogel-based coating mortars have declared thermal conductivities of 0.03-0.05 W/(m • K), similar to those of conventional thermal insulation materials. Due to the high porosity and fragility of aerogel granules, the material obtains a reduced mechanical strength compared to conventional mortars. Recently, there has been a large research effort on developing new mixtures with improved thermal and mechanical properties. This paper presents and evaluates two-dimensional numerical simulations, based on the random packing technique, as an alternative method to laboratory measurements in predicting the effective thermal conductivity of these mortars. Experimental data from the literature, on thermal conductivity of aerogelbased coating mortars containing 50-90 vol% aerogels were used to validate the simulation results. In this preliminary validation study, a relative error of 6-10% was observed. Future work can focus on improving the accuracy and including the prediction of mechanical properties in the suggested model.

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Mathematical Expressions for Prediction of the Effective Thermal Conductivity of Perfectly Packed Two-Phase Mixtures

Hagentoft,

Karim

2023

Environmental Science and Engineering

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This paper introduces new and handy mathematical expressions for predicting and understanding the effective thermal conductivity of two-phase homogeneous mixtures. In a two-phase mixture, particles of the dispersed phase are mixed in the matrix of the second phase. A primary purpose of the proposed model is to predict and understand the effective thermal conductivity of high porous thermal insulation materials, for which many other similar analytical models offer less accuracy. The presented expressions assume a perfectly packed mixture and consider the thermal conductivity of the two phases, the proportion and the particle size of the dispersed phase. The proposed model includes non-dimensional heat loss factors, calculated by two and three-dimensional numerical simulations. In the continuation of the work presented, an experimental study is planned to evaluate the accuracy of the model, compared to other existing analytical solutions, and the validity of the assumptions made.

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Knowledge gaps regarding the hygrothermal and long-term performance of aerogel-based coating mortars

Cited by 15 publications

References 66 publications

Increasing Water Absorptivity of an Aerogel-Based Coating Mortar in Subsequent Wetting and Drying

Increasing Water Absorptivity of an Aerogel-Based Coating Mortar in Subsequent Wetting and Drying

Determination of the Effective Thermal Conductivity of Aerogel-Based Coating Mortars Using Numerical Simulations—Random Packing

Mathematical Expressions for Prediction of the Effective Thermal Conductivity of Perfectly Packed Two-Phase Mixtures

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