Probabilistic assessment of the impact of material properties on the risk of frost damage in masonry constructions

Klaas Calle,Nathan Van Den Bossche

doi:10.1051/matecconf/201928202084

Abstract

Historically valuable buildings often contain a huge energy saving potential due to their current lacking thermal performance of the building envelope. Next to this, unfortunately insulation measures, which normally occur at the inside, induce a decrease in the temperature and drying potential of the structure which results in a risk for frost damage. To validate this risk Heat, Air and Moisture simulations are a valuable tool. Heritage facades often consist of masonries, which are known to have a complex hygrothermal behaviour. Therefore nowadays a homogenization of the masonry, for example to a homogenous brick wall, is often assumed to save computational time. Nevertheless these homogenizations, which include neglecting mortars, can have a drastic impact on the hygrothermal behaviour of masonries. Hence this study compares the impact of basic material parameters for the brick, pointing mortar and bed mortar of a masonry separately under a constant indoor and outdoor climate based on probabilistic simulations. The evaluation is done for three frost related criteria. Generally, the main impact parameters for the one and a half brick construction are found to be quite similar for interior insulated and not insulated cases but diverse between the chosen criteria.

Highlights

Probabilistic analyses are highly valuable to investigate the dominant impact parameters for certain damage criteria
This paper investigates the dominant impact parameters on material level of a one and a half brick masonry constructioninsulated cases
The first criterion is the maximum amount of critical freeze-thaw cycles (FTC) [-] with the critical moisture content equal to 25% of the effective moisture content https://doi.org/10.10 51/matecconf /201928202084

Summary

Introduction

Probabilistic analyses are highly valuable to investigate the dominant impact parameters for certain damage criteria. During the renovation process of historically valuable brickwork facades with interior insulation, the question of risk inducement related to frost damage is quickly asked. Based on the basic principles behind frost damage [1] it is clear that both the moisture content and the temperature play an important role. This paper investigates the dominant impact parameters on material level of a one and a half brick masonry construction (un)insulated cases. One of the main challenges in probabilistic risk assessment with Heat, Air and Moisture(HAM) simulation is the computational time. Https://doi.org/10.10 51/matecconf /201928202084 solvers this can be partially overcome even for 2D construction, which allows us to implement a pointing mortar(PM), a bed mortar(BM) and brick(B) in the simulated section of a masonry construction

Construction

Sampling

Sample size

Evaluation criteria for frost damage

Results and discussion

Conclusion