4.1 Evaluation and prioritization of the degree of pathological manifestations of the Stone Chalet building
Following a joint analysis conducted by four professionals and researchers, the structural pathological manifestations of the historical building Stone Chalet were classified, resulting in the conclusion that it presents a high degree of risk. This diagnosis is based on the pathological manifestations that fall within the criteria of severity, urgency, and trend, reaching maximum and high degrees according to the GUT Matrix.
Thus, these manifestations are associated with the potential loss of human lives, significant environmental impacts, and imminent threats to the structural integrity of the building. Therefore, these events are ongoing or about to occur, with immediate or short-term evolution. Table 1 presents the list of pathological manifestations of the studied building and their respective scores in the GUT Matrix.
Table 1
– Result of the GUT Matrix for the Stone Chalet Building
Pathological manifestations | Engineer 1 | Engineer 2 | Building technician 1 | Building technician 2 |
Fragmentation of the guardrail structure | 1000 | 1000 | 1000 | 1000 |
Cracks in cement flooring | 640 | 640 | 640 | 640 |
Cracks in staircase steps (structure) | 384 | 384 | 384 | 384 |
Wear of the wooden lattice (roofing) | 384 | 384 | 384 | 384 |
Corrosion in metal structure (pillar) | 384 | 384 | 384 | 384 |
Cracks in masonry | 288 | 384 | 384 | 288 |
Pest infestation (termites) | 288 | 288 | 288 | 288 |
The presence of leakage in the slab | 288 | 288 | 288 | 288 |
Cracks in wooden flooring | 288 | 216 | 288 | 216 |
Mold on masonry | 108 | 108 | 108 | 108 |
Disintegration of mortar due to capillary rise of water | 108 | 108 | 216 | 216 |
Efflorescence on masonry | 108 | 108 | 108 | 108 |
Staining on the facade masonry | 108 | 108 | 108 | 108 |
Unprotected circuit breaker box | 80 | 80 | 80 | 80 |
Exposed hydraulic installation pipes | 54 | 54 | 54 | 54 |
Peeling of paint on masonry | 54 | 54 | 54 | 54 |
Peeling of paint on window frames | 54 | 54 | 54 | 54 |
Wear on wooden flooring | 54 | 54 | 54 | 54 |
Staining on the ceiling lining (leakage) | 54 | 108 | 54 | 54 |
Wear of wooden window frame components | 54 | 54 | 54 | 54 |
Grounded hydrosanitary junction box | 36 | 36 | 36 | 36 |
Damaged glass elements of the window frames | 9 | 9 | 9 | 9 |
It is observed that there are discrepancies in the scoring assignments for the pathological manifestations regarding each parameter, as analyzed by the evaluators. Additionally, it is highlighted that the GUT Matrix has limitations in prioritizing equal scores, resulting in the same order of priority. Therefore, the Delphi Method was employed to overcome this issue and assist in the decision-making process to establish priorities in corrective interventions in buildings.
For the application of the Delphi Method, iterations were conducted with the participation of the involved professionals, mediated by a moderator. After two rounds of discussions, a consensus was reached among the evaluators, resulting in the classification of the priority order for interventions regarding the pathological manifestations in the Stone Chalet building, as presented in Table 2.
Table 2
– Classification of priority order for interventions in the building
Pathological manifestations | Priority order |
Fragmentation of the guardrail structure | 1º |
Cracks in the cement floor | 2º |
Cracks in staircase steps (structure) | 3º |
Corrosion in metal structure (pillar) | 4º |
Wear on the wooden lattice (roofing) | 5º |
Cracks in masonry | 6º |
The presence of leakage in the slab | 7º |
Termite infestation | 8º |
Cracks in wooden floor | 9º |
Mold on masonry | 10º |
Disintegration of mortar due to capillary rise of water | 11º |
Efflorescence on masonry | 12º |
Stains on the facade masonry | 13º |
Exposed electrical wiring | 14º |
Staining of the ceiling lining (leakage) | 15º |
Exposed hydraulic installation pipes | 16º |
Wear on wooden flooring | 17º |
Wear of wooden window frame components | 18º |
Peeling of paint on masonry | 19º |
Peeling of paint on window frames | 20º |
Grounded hydrosanitary junction box | 21º |
Damaged glass elements of the window frames | 22º |
Thus, it can be observed that the highest intervention priorities are related to the pathological manifestations identified in the structural system of the building due to the critical risk they represent to the structure's integrity and the users' safety. Figure 7 presents images of the records of six priority pathological manifestations for intervention, according to their criticality.
It is important to emphasize that potential construction flaws directly associated with moisture and possible overload resulting from the loss of efficiency of structural elements have a significant impact on the health of the building, manifesting through cracks that compromise its stability, also having relevant intervention priorities.
4.2 Application of Infrared Thermography in the Stone Chalet Building
After classifying the pathological manifestations of the Stone Chalet building through visual inspection and following the intervention priority order determined by the GUT Matrix, it was decided to employ IRT as a non-invasive and non-destructive method to analyze its hidden pathological manifestations. The aim was to identify construction flaws directly related to moisture, as it was observed that its presence affects the efficiency of other analyzed construction systems.
According to the adopted methodology, measurements were taken during the daytime, at 8:00 a.m. and 4:30 p.m. It is emphasized that this factor is of paramount importance, as the thermal equilibrium between the masonry and the environment can impact the detection of pathological manifestations by the thermal camera, as can be observed in Fig. 8.
Thus, it is noted that, specifically under sunny conditions with higher temperatures in the late afternoon, moisture tends to manifest less evidently due to the thermal equilibrium between the wall and the environment. It is emphasized that such a phenomenon can affect the clarity and sharpness of the captured thermographic images. Additionally, factors such as weather, time of day, space limitations at the experiment site, and solar exposure and shading can influence the results obtained in the thermogram.
During the thermographic inspection of the analyzed building, 84 pairs of photo-thermal images were produced. To conduct a more detailed analysis, five specific areas of the building were selected as they presented thermograms with relevant temperature distribution profiles.
In the first area examined, a point with rising moisture was identified, disintegrating the plaster coating on the masonry, exposing the plumbing, and causing cracks, fissures, and paint peeling, as can be seen in Fig. 9, which illustrates the record of the pathological manifestation, as well as the thermographic images captured at the two designated times for the study.
Therefore, through IRT, points with rising moisture that was barely noticeable visually were identified. This conclusion is based on the temperature difference between the damp areas, due to capillarity, and the dry areas. The temperature tends to be lower in humid regions due to surface evaporation. From this perspective, IRT enabled highlighting these thermal differences, making it possible to identify the areas affected by rising moisture.
The second area analyzed encompasses the presence of infiltration and moisture on the wall, possibly originating from the building's water tank. It was observed that this manifestation extends throughout the entire length of the wall, resulting in mold, stains, paint peeling, cracks, dampening, and possible deterioration of the wooden elements of the roof. Figure 10 illustrates the described issue.
Upon analyzing the thermograms, it was observed that moisture typically manifests with lower temperatures, and thermal equilibrium can occur, as mentioned earlier. However, in the late afternoon, there is usually a reduction in temperature difference and less color contrast in the thermograms. Consequently, after a certain period when sun exposure ends, and the cooling process begins, moisture appears as a warmer region. This is due to heat retention by the water, which explains the reddish coloration observed in Fig. 9 (c).
Another area that aroused curiosity is related to a wall located on the main facade of the building. Several pathological manifestations were observed, such as paint peeling, cracks in the wall and floor, and mold spots. However, visually, it was not possible to determine whether there was ascending moisture in the masonry. Therefore, a thermogram was performed to investigate this issue, as shown in Fig. 11.
During the analysis of the images captured by the IRT in Figs. 10 (a) and (b), the existence of a temperature gradient on the lateral facade of the building was observed. It was found that conventional visual inspection, through the recording of familiar images, was not able to provide a clear distinction between the region affected by moisture, evidenced by bluish tones and lower temperatures, and the dry area with infiltration, visualized through warmer colors in shades of green, yellow, and orange, indicating higher temperatures.
In this scenario, based on the results obtained from the thermograms, it was possible to highlight these affected areas, thus confirming the presence of rising dampness in the masonry of the main facade of the Chalé da Pedra building. This finding reinforces the ability of thermography to detect moisture, even when it is not perceptible to the naked eye.
The walls of the main entrance also show signs of rising dampness. In Figs. 11 (a) and (b), it is possible to observe manifestations of problems such as efflorescence, stains, mold, and paint peeling caused by moisture. In turn, Figs. 11 (c) and (d) represent the thermograms obtained at 8:00 a.m., while Figs. 12 (e) and (f) depict the thermograms recorded at 4:30 p.m.
The analysis of the thermograms confirms the presence of moisture in the masonry in question. Observing the thermographic images at different times is noteworthy, clearly highlighting the areas with higher temperatures. However, it is necessary to emphasize that these areas do not exclude the possibility of moisture, as it may be linked to another construction flaw, such as the paint layer's deterioration. The latter may be responsible for the thermal anomaly in a yellowish tone recorded in the afternoon thermogram, escaping perception during visual inspection.
The internal region of the building revealed the presence of moisture spots on the slab, indicating a construction anomaly with the potential to affect other construction systems, as well as the safety of the building and its occupants. Thus, symptoms of this pathology, such as stains, paint peeling, and fissures, were identified during the visual inspection. In light of these indications, researchers and evaluators considered it pertinent to apply IRT to analyze the infiltration focus. Through Fig. 13, it is possible to observe both the construction pathology and the thermograms captured at the two measurement times.
Therefore, by using a temperature gradient, it was possible to identify the infiltration point, with the affected regions showing lower temperatures compared to the dry and intact areas of the slab. This temperature difference occurs due to the evaporation of water in the regions infiltrated, resulting in localized cooling, also known as a "cold spot."
It is relevant to mention that, after a conversation with the responsible administrator, it was reported that there was a recent incident involving the gutter and the roof of the cover in the area under analysis, which may have been the cause of the detected infiltration. Thus, the use of thermographic techniques allowed for a practical inspection of the building's condition, confirming that IRT is an excellent tool for detecting pathological manifestations, with an emphasis on moisture.
Furthermore, this non-invasive approach may also aim to assist in preventing more severe construction damage, avoiding additional repair costs. Additionally, IRT enables quick and efficient intervention, contributing to the conservation and durability of buildings, especially those of historical value.