Concrete is used worldwide for it is an exceptionally durable construction material. However, severe exposure conditions, material limitations, and construction practices lead to concrete deterioration which later causes structural deficiencies. A variety of factors can be associated with concrete deterioration. Corrosion of steel reinforcement is considered to be the leading factor in this regard. In normal atmospheric conditions, steel and most of the others metals are thermodynamically unstable and tends to revert back to its original state.
Causes of concrete deterioration:
When reinforced concrete is exposed to chloride ions, it leads to premature corrosion of steel reinforcement. Chloride ions penetrate into concrete and cause steel corrosion only when moisture and oxygen are available to facilitate the reaction. In the presence of moisture and oxygen, steel becomes more vulnerable to corrosion when chloride content exceeds a certain limit.
Water expands about 9% when freezes. When water freezes inside concrete, it produces pressure in pores and capillaries, resulting in cracking, crumbling, and scaling of concrete. Concrete with minimum permeability resists the water penetration and perform better when exposed to perpetual freeze-thaw cycles.
Concrete is usually effective against environmental conditions, water, and chemicals. However, under some severe chemical conditions, it deteriorates rapidly. It can only withstand occasional acid attacks. Surface protective treatments can prevent acid attacks and help concrete structures achieve better resistance against chemicals.
Concrete usually perform well in heat and fire. However, when heat exceeds a certain point, it damages the strength of concrete. Exceptionally high temperature or fire decreases the stiffness and strength of a structure. Flexural strength, compressive strength, and modulus of elasticity are effected under highly elevated temperature.
Types of concrete deterioration:
One of the properties of concrete is that it contracts when cooled and expands when heated. Water-cement ratios, cement content, age, humidity are some of the factors that determine the contraction or expansion of concrete. Proper concrete detailing and design can prevent cracking. Formed surface, earthquake damage, and loss of support are some of the types of deterioration.
Without an effective reinforcement material, it is hard to build sustainable concrete buildings. Plenty of research has already been made to develop a reinforcement material that can minimize the limitations of concrete and make it effective against chemicals, water, salt, and other environmental conditions. Deterioration of buildings has serious economic and environmental impact. Sustainability and long service life of a project can be ensured by reinforcing concrete with material that can resist corrosive agents as well as natural calamities.