Introduction: 

Business pathology defines two major work processes include Producing information that will assist in the effective management of service loss and developing methodologies for assessment of defects and failures and consequential service loss. Three types of deteriorations can be found in any construction namely, Dampness, Bio-decay and Cracking (Kumar & Gardoni, 2013). The purpose of the inspection is to identify the causes and provide remedy to secure the building from potential hazards. This systematic assessment includes five stapes mainly Symptom, Condition, Causes, Hazard identification and remedy (Lerma et al., 2014). In this report two case studies about building deterioration have been presented while assessing their problems with proper inspection and diagnosis tools of building pathology. The report also provides the remedies and further required assessment for these two building. 

Building A is a housing building situated in residential area near Quarry Bay Park, Hong Kong. The apartment is at 7^th floor sharing a common passage or corridor with other 4 apartments. The floor plan of the chosen apartment is presented below. The building was founded in 2006.

The internal wall of the bed room had some issues regarding damping and tarmac surface. The damp is highly concentrated at one of the wall of the bedroom. Besides, different scattered damp was present across the interior wall of the kitchen as well. These damps were not depends on the exterior weather or atmosphere. However, these spots and tarmac increase when the residents stay in the house constantly more than 24 hours.

Initial analysis and assumption

Damp causes because of the increased moisture in concrete or in other internal layer of the walls, such as bricks, metallic foundation, cladding and others. In this case the damp varies depending on the utilisation of the house in spite of raining or other external causes. Therefore, the problem could be caused because of the faults in plumbing system or other internal cladding issues.

For the initial testing 2 types of investigation procedure has been used including the visual investigation and the instrumental investigation. For instrumental investigation a measurement tape and a moisture meter have been used. For further assessment other investigation methods will be used as per the requirement (Karagiannis et al., 2016). 

Initially the internal wall has been investigated From visual inspection of indoor and outdoor many issues has been found which may and may not be contribute to the damp of wall. The major finding is the position of the damp which has been identified at the intermediate wall between bedroom and toilet.

The bath room and toilet has been investigated to find any clue of source. The concealed water line for shower and water tap is situated at the other side of the damped wall. From the visual inspection it can be said that internal dispute of water system can cause leakage of water within the wall.

From the moisture measurement readings the following readings has been found at the damp area of wall. The moisture test has been conducted by considering both horizontal and vertical test. The vertical test was conducted by taking 4 moisture values at the period of 50 cm. The horizontal testing has been conducted with same procedure. The following table presents the detail value

From the instrumental data about moisture level it is clear that the mean moisture level of both horizontal and vertical area is higher than the ideal value that is 5 to 14% Mc. At the same time the mean value of vertical points are bigger than the values found form horizontal measurement. The following diagram shows the estimated situation from the bedroom view.

As per the current assessment report it has not identified that if only the concealed pipeline is causing the damping issues or there are other internal concealed blockages are responsible. Therefore, to investigate further level NDI or non destructive investigation is not enough. The concealed pipelines have to be exposed by drilling through the brick layers of the wall

The durability of concealed pipeline depends on the quality of materials and the internal distance within two joints in plumbing work. As per the investigation it has been found that using the pipeline more causes more damping and moisture spreading. Besides, from the damp measurement analysis it has been clear that some of the vertical concealed pipelines of toilet-bedroom boundary wall are causing lockage (Kylili et al., 2014). From the following diagram the situation could be understood.

From the above diagram it can be seen that due to the thick layer of tiles on Toilet side, the moisture have not been exposed. However, old and weak concrete work helped the water and moisture to be exposed in bedroom side of the boundary wall.

Damp and moisture spreading can have devastating effect on the walls that can weaken the foundation of the building even further. According to the building history the apartment was built 9 years ago and no repairing and maintenance work has been done in the plumbing and other concealed lines. As a result of the weakening the walls other decays can be occur like crack or building movement. Damping because of the external water source can be resisted comparatively easily. However, moisture from internal layer can spread very faster while having multiple bad effect on the structural metals of the building as well (Moropoulou et al., 2013). Rapid internal spreading of moisture can reduce the load endurance of the wall causing structural defects. If the metallic structure of the building caches the moisture it will decay rapidly causing rapid weakening of building. Other apartments of this building will be affected from this. Long time moisture concrete can help to initiate bio-chemical degradation or decay. It could increase the impact exponentially leaving less option for repairing.

High moisture level caused by external source can be treated with external repairing through removing exterior cladding of the building and providing better water and moisture resistant claddings. However, in this case the moisture source is internal, which requires detailed inspection and detection of all plumbing failures and potential failures. After that the pipeline should be repaired or replaced by new pipeline with better concealing ability. Besides, the affected wall also require maintenance. The particular sections of the wall that grabbed the maximum amount of moisture should be reconstructed completely.

Restaurant R is a commercial building situated near high way of Quarry Bay Park, Hong Kong. The building was initially a very small warehouse and used as retail operation and storage. The main segment of the building was constructed in 1994. However in 2010 the main building has been extended aiming to build a hospitality premise. The following floor plan presents the 2d top down view of building.

Both internal and external wall of the dining room had some issues regarding cracking and fractured surface. The cracks are increasing rapidly across the exterior wall and the interior wall of the dining area. Some of the claddings of the exterior side of the wall even have even fallen apart. The cracks are net structured where both horizontal and vertical cracks are present. The cladding of interior side of the wall became fragile causing dislocation of cladding.

Initial analysis and assumption

Crack is a very common form of deterioration and structural failures. Crack can be horizontal or vertical. Horizontal crack could appear because of the moisture, chemical decay, weakening of cladding and others. However vertical cracks are rare and display major faults and potential risks. In this case both horizontal and vertical cracks have been identified in net structure. It is also known that this portion of the building older than 24 years. In such old buildings material weakening is usually found as the major cause of the crack. Therefore it can be assumed that the building material of the wall crossed the maximum time of durability and the load is causing more strain than its capability (Barbin et al., 2013).

To test the type of the crack the gap and depth of the crack should be measured. Due to lack of time the relative movement between walls could not be measured. 3 types of inspection have been conducted to identify the possible causes of this situation. First the visual inspection has been conducted to find any other symptoms of deteriorations and the expansion of the current deterioration. The gap of the cracks has been measured by vernier calliper to get a fine measurement of cracks. After the detection of the crack type the UPV or Ultrasonic Pulse Velocity testing has been used measure the condition of the concrete and the break work as well.

Both internal and external part of the building has been inspected. The following image is the photographic capture of internal wall of the dining space of the restaurant.

From the interior inspection it has been found the interior part of the wall has some shrinkage type cracks. Majorly the diagonal cracks has been fund with some vertical hair cracks. These cracks have been found on only the companied wall. The following picture shows the condition of exterior part of the wall.   

From the exterior it has been identified that the cladding of the exterior part is showing more cracks with better depth. The exterior part of that particular wall showed vertical, horizontal and diagonal crack. These net like structure clearly indicates underlying stress and even constructional defects.  

In next phase the crack measurement has been conducted and the following table presents the results of the measurement.

From the above results it is clear that cracks indentified both in internal and external side of the wall were not caused by the thermal expansion or minor stress in cladding or shrinkage. The mean value of exterior side is 4.1 mm which clearly indicates the structural disputes.

The results of the UPV or Ultrasonic Pulse Velocity testing have been presented in the following table. The test has been conducted in a linear direction from one side of the wall to other side to measure the difference in decay. The presented value of each record is the mean of exterior and interior material testing. The wall was 12 meter wide, therefore, the testing has been done periodically by placing 10 different position with 1.2 meter distance in each.

From the above results it has been found that the mean velocity of the UW or Ultrasonic wave through the wall material is 3.05 km/sec with the standard deviation of the 0.57 km. Therefore, the speed ranged from 2.48 to 3.42. As per the bandwidth of measurement, reading lower than 3 should be considered as the bad condition of the construction quality. The exact middle of the wall showed minimum value, which was 2. However, the terminal point has shown value greater than 3.5 km/sec. 

To examine the source of structural weakening more in-depth examination will be required. The Thermal monitoring and X-ray vision inspection are required to find internal damages and decays. Apart from that other part of the building should be also investigated through visual and instrumental inspection.  

Possible Causes

From the historical analysis of the building it has been found that the building is at least 24 years old. Therefore, the particular wall has already lost it stress handling capacity. From the width measurement it is also clear that structural issues are causing this cracks. From the UPV testing it has been found the building material of the wall is getting weak and loosing tension handling quality (Regier & Hoult, 2015). At the same time it has been identified that the thickness of the exterior walls of the extended area is higher than the thickness of the exterior wall of dining space. Therefore different stress on the same wall is causing unequal load, which is causing rapid cracking and fracturing of internal and external layers of wall. 

Multiple types of cracks due to dispute in construction material can have devastating effect on the walls that can weaken the foundation of the building even further. As a result of the weakening the walls the vertical cracks have been occurred which have shown the risk of falling down of the wall. These risks can be more destructive in case of any building movement. Cracking because of material quality can also cause unequal load in other part of the building while causing extended weakening (Gucunski & National Research Council, 2013). If the metallic structure of the building experiences the unequal load the impact of the deterioration will be permanent. Total foundation of the building can collapse if it will remain unrepaired. 

Hair crack by poor cladding material or thermal expansion can be treated with external repairing through filling the cracks of repairing the cladding of the building and providing better thermal insulator claddings. However, in this case the decay of materials is causing the issues which requires compete reconstruction of the wall (He et al., 2013). After reconstruction the wall the other part of the building should be also investigated while making adequate arrangement to resist any natural movement of soil and foundation.

Conclusion: 

From the above report it has been found that Symptom, Condition, Causes, Hazard identification and remedy are the five major factors of above case studies. In these both studies the further assessment and diagnosis is required which may include the Destructive Inspection procedures. From the first case study has been found that some of the vertical concealed pipelines of toilet-bedroom boundary wall are causing lockage. From the case study 2 it has been found that the building material of the wall is getting weak and loosing tension handling quality.

References: 

Barbin, D. F., ElMasry, G., Sun, D. W., & Allen, P. (2013). Non-destructive determination of chemical composition in intact and minced pork using near-infrared hyperspectral imaging. Food chemistry, 138(2-3), 1162-1171.

Gucunski, N., & National Research Council. (2013). Nondestructive testing to identify concrete bridge deck deterioration. Transportation Research Board.

He, H. J., Wu, D., & Sun, D. W. (2013). Non-destructive and rapid analysis of moisture distribution in farmed Atlantic salmon (Salmo salar) fillets using visible and near-infrared hyperspectral imaging. Innovative Food Science & Emerging Technologies, 18, 237-245.

Karagiannis, N., Karoglou, M., Bakolas, A., & Moropoulou, A. (2016). Building materials capillary rise coefficient: Concepts, determination and parameters involved. In New Approaches to Building Pathology and Durability (pp. 27-44). Springer, Singapore.

Kumar, R., & Gardoni, P. (2013). Stochastic modeling of deterioration in buildings and civil infrastructure. In Handbook of seismic risk analysis and management of civil infrastructure systems (pp. 410-434).

Kylili, A., Fokaides, P. A., Christou, P., & Kalogirou, S. A. (2014). Infrared thermography (IRT) applications for building diagnostics: A review. Applied Energy, 134, 531-549.

Lerma, C., Mas, Á., Gil, E., Vercher, J., & Peñalver, M. J. (2014). Pathology of building materials in historic buildings. Relationship between laboratory testing and infrared thermography. Materiales de Construcción, 64(313), 009.

Moropoulou, A., Labropoulos, K. C., Delegou, E. T., Karoglou, M., & Bakolas, A. (2013). Non-destructive techniques as a tool for the protection of built cultural heritage. Construction and Building Materials, 48, 1222-1239.

Regier, R., & Hoult, N. A. (2015). Concrete deterioration detection using distributed sensors. Proceedings of the Institution of Civil Engineers-Structures and Buildings, 168(2), 118-126.