Expert Tips
BENEFITS OF WATERPROOFING
1- Waterproofing Protects the Structure
The damage caused by water to structures poses a threat to life and property safety, especially in areas with earthquake risks. Water that seeps into the building's reinforcement through any means can cause the reinforcement to lose its properties by freezing or undergoing chemical reactions. The loss of reinforcement properties negatively affects its strength and durability.
We usually cannot see the damage that water causes to the durability of our buildings with the naked eye, but we can notice it when we encounter the consequences. In a major earthquake, it is almost impossible for a corroded building to remain standing. Therefore, waterproofing is of vital importance, especially in countries located in earthquake zones like Turkey.
In general, concrete protects the embedded reinforcement against corrosion. As soon as the reinforcement is embedded in concrete, a thin film layer forms and adheres to the steel, creating resistance against corrosion. This resistance is directly related to the high alkaline environment and electrical resistance of the concrete. Ions in the moisture in the capillary pores of the concrete play a role in electrical conductivity. High electrical resistance can also mean durable concrete.
There are 4 main factors that cause and sustain the corrosion of reinforcement in structures:
• Deterioration of the protective passivation layer around the reinforcement due to reactions caused by carbon dioxide or chlorine,
• Water distributed in the capillary pores of the concrete, acting as an electrolyte,
• Oxygen entering through the pores of the concrete.
• Moisture due to condensation occurring inside the reinforced concrete if precautions are not taken.
One of the conditions that cause corrosion of the reinforcement by breaking the film layer on the concrete is carbonation. The chemical reaction between atmospheric carbon dioxide and cement in the concrete causes the concrete to shrink, thus increasing cracks. At the same time, the decrease in the pH value of the concrete (the pH value of normal concrete is between 12.5-13.5, which is sufficient to prevent corrosion) leads to a decrease in alkalinity at the interfaces and deterioration of the existing protective layer. Another reason for the deterioration of the protective layer is the presence of chloride ions. As a result, in both cases, the necessary conditions for the onset of corrosion are formed (pH value falling below 9), and the process begins. Depending on the environmental conditions, iron oxide formations occur on the reinforcement surface at a certain rate, with a volume 2.5 times that of the reinforcement.
The resulting rust cracks the existing concrete if there is also an insufficient concrete cover problem. With the spalling of concrete, the reinforcement is exposed. Due to contact with air, an increase in the rate of corrosion becomes inevitable.
The loss in the reinforcement cross-section due to corrosion causes the reinforcement to fail to meet the initially designed calculation values. This is an undesirable situation in terms of the load-bearing capacity of the building and, consequently, structural safety. While an S420b class Ø12 steel with a design strength of 365 MPa can initially carry a load of 41.3 kN, assuming a corrosion-induced reinforcement section loss of 0.25 mm/year, it can carry 25.9 kN after 5 years and 5.8 kN after 15 years. Under these conditions, the reinforcement will completely lose its load-bearing capacity after 24 years.
2- Waterproofing Provides Comfort
As indispensable as water is for us, it is equally essential to protect our structures from it. Soil moisture and non-pressurized water pass through the pores of structural elements, causing mold, black stains, and fungi to form on the interior surface. This leads to the decay of natural materials such as wood on the interior surface, the swelling and peeling of plaster, and the rusting of reinforcement in columns and shear walls, thus disrupting our comfort.
Moisture and the mold it causes lead to the formation of bad odors in spaces. This situation will disturb the people in the environment. By preventing moisture through waterproofing, the possibility of these bad odors spreading, which creates negativity in terms of human comfort, is also eliminated.
Waterproofing ensures comfortable structures by preventing water from dripping into our rooms while also preventing the formation of bacteria, mold, and other organisms.
3- Waterproofing Contributes to the Economy
Structures, whose economic values are increasingly important today, need to be long-lasting. Today, the average lifespan of a building is about 50 years. The adverse effects of water reduce the lifespan of structures. This is an economic loss. With waterproofing, this loss will also be eliminated.
92% of our country's surface area and 95% of its population density are in earthquake zones. According to data from the Ministry of Public Works and Settlement, earthquakes that have occurred in the last 58 years have caused the loss of 58,202 citizens' lives, injured 122,096 citizens, and resulted in the destruction or severe damage of approximately 411,465 buildings.
In a report prepared by Dünya newspaper, it was stated that in inspections carried out by the Istanbul Metropolitan Municipality Damage Assessment Commission on 55,651 residences and workplaces, 79% of the examined buildings were found to be damaged. According to the report, the causes of damage were determined as follows: corrosion (rusting) caused by moisture in 64% of the examined buildings, lack of materials in 41%, watering of concrete during the construction phase in 18%, aging and wear in 11%, and project errors in 3%. The same report stated that construction unsuitable for the ground was detected in 21% of the buildings, and issues such as removal and drilling of load-bearing elements were found in 6%.
The cost of waterproofing during the construction phase is approximately 3% of the building cost. The soundness of buildings is the most important factor to consider. Consequently, the benefit provided by waterproofing is much more important than its cost.