Dulce Franco Henriques
3 CASE STUDY
3.1 Collection of information
This case study is an administrative building in the center of Lisbon in the neighborhood of Pe-na, lying in the vacant state since 2009. The building was built in 1990 with three basements be-low ground level and ten floors above (considering the attic), making a gross building area with about 5488 m2, and a rentable area with 5225 m2. The structure is in reinforced concrete with the constructive typification of a recent building. In Figure 2 it can be observed some compart-ments of the building in study.
The underground floors are characterized by peripheral shaped containment walls associated with simple 15 cm thick brick masonry plastered and painted.. The interior walls are constituted by a simple 11 cm thick brick layer, finding the same plastered and painted with plastic paint. The underground floors pavement is coated with floor screed on the parking places, and ceramic mosaic in the compartments and sanitary facilities.
The upper floors are characterized, in most situations, by partitioning walls of removable type, with the exception of sanitary facilities, where there are simple 11 cm thick brick masonry plastered and painted with plastic paint. The exterior walls are constituted by double 7 cm thick brick masonry, with a 10 cm air box, unventilated and without thermal isolation filling, finding the same plastered and painted with plastic paint on the interior envelopment. Regarding the ex-terior facades, they are coated with a pinkish limestone, stabilized with staples. The pavements of the main administrative compartments on the upper floors are, in most cases, constituted by wood parquet floor varnished, ceramic mosaics (in sanitary facilities) or granite stone mosaics (in hallways). Regarding the typology of frames used in the front and rear facades, it was used a dark brown aluminum frame, with double glaze bronze colored windows (5mm + 5mm) and without thermal cutting.
Figure 2. Representation set of most floors compartments inserted in the building.
Considering the building seismic behavior, the vertical elements of great rigidity that are re-sistant in seismic situations are generally the stairwells and lifts. In conclusive results during the methodology of the proposed work in this case study, was taken into account the information provided in the urban documentation and plants with a 1:100 scale representation. However it was not afforded access to structure projects and original specialties.
3.2 Inspection, Identification and Classification of Anomalies
Regarding the qualitative summary evaluation of anomalous situations evidenced in the eigh-teen inspections made to the building in study, it can be noted that there is a great variety of anomalies types per floor, which are repeated from the second floor up, inclusive. In the three basements it’s recurrent the observation of defined cracks at 45° in peripheral and partitioning walls (Fig. 3a), cracks without defined orientation, and in equal circumstances it can be ob-served efflorescence effect on interior walls (Fig. 3c).
Figure 3. Representation set of abnormal situations detectable in the building in study.
Referring to the first and ground floors it’s visible the permanence of anomalies in the wood pavement due to the flooding that occurred in 2011, leading to the degradation of the coating (Fig. 3d) and development of fungi. Also on the first floor its observable a punctual occurrence of plastic paint pellicle detachment (Fig. 3e) on a wall oriented south.
Given that the situations of exterior aluminum frame material degradation (Fig. 3h) are con-stant in all the above ground floors, such events tend to get worse from the second floor up, causing the walls plastering (Fig. 3f) detachment due to water infiltration.
Finally, it is important to mention the frequency of joints spectrums (Fig. 3b) in walls orien-tated north along the building, being also observable on the eighth floor terrace the deterioration and progressive detachment of the waterproof coating (Fig. 3g).
Given the immense diversity of anomalies present in the building, it was established an iden-tifying classificatory system taking into account the type of building elements, and in some situ-ations, the nature of the coating in which the anomalies were inserted (Tab. 1). As such, at this stage of anomalies identification it was sought the use of a clear and coherent classification
sys-tem, developed through a logical organization of information, trying to avoid an exhaustive and repeated detailing of the data acquired along the process.
Table 1. Representation of the classification of anomalies evidenced in the building analyzed.
Classification of the anomalies by
building elements Description of the anomalies Nomenclature Designation A.Anomalies in Interior and Exterior
Walls A.1 Structural Fissuration
A.2 Non Structural Fissuration A.3 Paiting Detachement / Dustiness A.4 Eflorescence in the final coating A.5 Plaster detachement
A.6 Appearance of joints spectrum in interior walls
B.Anomaly in Interior Wood
pave-ment B.1 Pavement detachement
B.2 Fungal growth
C.Anomaly in stone pavement C.1 Eflorescence in the surface
C.2 Plant growth
D.Anomaly in stone wall outside D.1 Eflorescence in the joints
D.2 Coating degradation
E.Anomaly in Exterior Aluminium Frame
E.1 Material degradation
F.Anomalies in roof and terrace F.1 Waterproof coating detachment G.Anomalies in Pillars G.1 Structural fissuration
G.2 Paiting detachement / dustiness G.3 Eflorescence in the final coating H.Anomalies in Pillars and
rein-forced concrete stairs support
H.1 Detachment and fissuration in Pillars H.2 Carbonation in Pillars
H.3 Chloride presence in Pillars
H.4 Fissuration on main stairs structure sup-port
3.3 Identification and Classification of Diagnosis Techniques
In the present case study, we used various diagnosis methods (Fig. 4), taking into account the different types of building elements existing in the building in question.
Figure 4. Representation set of the diagnosis techniques used in the building.
Thus in the exposed reinforced concrete construction elements it was used a esclerometer and ultrasound device (Figs. 4e, 4c) (for evaluating the mechanical resistance), a thermometer (Fig.
4f), an electrical resistivity measuring device (Fig. 4h) (to identify areas where the armatures corrosion is present or about to occur), the tests of phenolphthalein solution and silver nitrate (to investigate the phenomena of carbonation and the presence of chloride respectively), and a hu-midimeter (Fig. 4d). It’s important to note the use of the pachometer (Fig. 4b), in reinforced concrete elements, as an aid to the inspection procedure and other diagnosis techniques (e.g. ul-trasound). Regarding the exterior and interior walls of brick masonry, it was used essentially the fissure and/or cracks comparator (Fig. 4a) and a thermal camera (Fig. 4g), making also laborato-ry x-ray diffraction test, in order to identify the composition of salts from samples collected in situ.
In order to systematize the selection of the diagnosis methods used in the inspection, it is rec-ommended that there is a classification of them (Tab. 2), in which, beyond the visual observa-tion and the complementary means are also included the in situ nondestructive assays and the laboratory tests. The classification criterion recommended is the working principle of the tech-nique, instead of the type of anomaly diagnosed or the location of the procedure.
Table 2.Representation of the classification of diagnosis techniques in the building analyzed.
Classification of anomalies by build-ing elements
Description of anomalies Nomenclature Designation Visual Inspection – Assisted Visual
Analysis TD-1-AVA-1 Fissures Comparator
Nondestructive in situ tests TD-2-ND-1 Humidimeter TD-2-ND-2 Thermography
TD-2-ND-3 Armatures Detector (Pachometer) TD-2-ND-4 Test of silver nitrate placement TD-2-ND-5 Thermometer
TD-2-ND-6 Esclerometer TD-2-ND-7 Ultrasound
TD-2-ND-8 Phenolphthalein test
TD-2-ND-9 Electrical Resistivity Measurement Laboratory Tests - Identifying the
Presence of Salts TD-3-IPS-1 X-Ray Diffraction
Given the information provided in Table 1 and Table 2 it will be presented bellow an exam-ple of a representation (Fig. 5), relatively to the location of anomalies and diagnosis techniques implemented on the second floor of the building in study.
Figure 5. Designation and location of anomalies and diagnosis techniques, present on the second floor of the building in study.
3.4 Selection of Intervention Measures
Rehabilitation and maintenance techniques should also be subject to classification that takes into account two aspects: prevention (eliminating the anomaly) and correction (eliminating the cause). As such, in an early stage of the selection of intervention measures more suited for each
anomaly evidenced, it was privileged the options for intervention of corrective nature, although in some situations it was appealed the use of preventive measures.
During the phase of guidelines establishment for the strategy of intervention of each anomaly evidenced it has been produced documents that contain the identification, description and loca-tion of the anomaly in quesloca-tion as well as the designaloca-tion of the various diagnosis techniques used, the cause (s) associated with and finally some brief description (s) of the intervention pro-posal (s).
4 CONCLUSIONS
Regarding the results obtained from the inspections conducted on all floors of the building in study, it was found a total of 373 anomalous situations.
Given the division of anomalous situations by constructive elements, from Figure 6, it’s poss-ible to verify that localized anomalies in the interior and exterior walls are the most assiduous in the building, reaching 50% frequency of occurrence, in contrast with the anomalies present in the terrace and roof, which meet only 1 % frequency of circumstance. However the more ob-served anomalous situation in the development of the above ground floors in the building it’s ef-fectively the degradation of the exterior aluminum frames material, where such condition was assessed on 64 occasions, with an average observation frequency by floor equal to 7.
Figure 6. Representation of the proportion of anomalies evidenced by constructive elements.
Regarding the identification of the causes of the anomalies highlighted, about 30.56% of all anomalies emerged due to the poor quality of materials employed, in opposition to the occurring casualties during the utilization phase, only 0.80% (Fig. 7a). Despite such facts, it should be noted that, from all the anomalies, about 14.75% of them occurred derivative to human caused accidents (flooding on the first and ground floors). Regarding the frequency of the typology of diagnosis techniques (Fig. 7b), held in most building, the in-situ non-destructive tests were the most performed (72%). However , it was in the second floor where it was performed the largest number of diagnosis tests, about 46 in total, unlike the third lower floor, where it was held only 10.
Figure 7. a. Representation of the distribution of causes associated with the observable anomalies; b.
Usage distribution of the three types of diagnosis techniques.
Given the testing frequency, the measurement of moisture content on the walls coating and on the reinforced concrete surfaces was the most used diagnosis technique (Fig. 8), over all the floors of the building. It’s relevant to mention that the visual inspection supplemented by pho-tographic and video graphic inspection was the most used inspection method, where in some anomalies, served as a diagnosis method.
Figure 8. Representation of the utilization frequency of the diagnosis techniques.
It can be concluded that with the establishment of a plan of inspection and diagnosis in recent buildings (characterized by objectivity and consistency in the collection and organization of in-formation available and acquired), provides in the long term, a range of advantages for the ac-tual and future owners, since they can be aware of the causes/sources and effects of the anoma-lies, being able to choose with fundament the strategy measures of intervention more adjusted for each anomalous situation found in the analyzed buildings.
REFERENCES
Aguiar, J., Paiva, J., Pinho, A. 2006. Guião de apoio à reabilitação de edifícios habitacionais. Lisboa:
Laboratório Nacional de Engenharia Civil.
Brito, J. 2009. Sistemas de inspecção e diagnóstico em edifícios. Actas do 3º Encontro sobre patologia e reabilitação de edifícios 1: 13-23.
Gaspar, P. & Brito, J. 2009. Tipos de vida útil das construções. Actas do 3º Encontro sobre patologia e reabilitação de edifícios 1: 301-302.
Haapio, A. & Viitaniemi, P. 2008. How workmanship should be taken into account in service life plan-ning. 11DBMC: 1466-1482.
Ribeiro, T. & Cóias, V. 2003. “”Construdoctor”: Um serviço de pré- diagnóstico via internet”. 3º Encon-tro sobre Conservação e Reabilitação de Edifícios (Tema III: Parque Edificado Recente) 2: 1037 – 1046.
1 INTRODUCTION