Factors Affecting Strength Of Concrete
While constructing any building, importance should be given to longevity and concrete strength.
Both the compressive & tensile strengths of the concrete are two major factors that influence the stability and the strength of concrete structure significantly.
The tensile stress of the structure is based on the reinforced bars & partly on the binding strength of the concrete itself, whereas the compressive strength of concrete is affected by the aggregate and cementitious material alias binder.
The environment-related conditions also reduce the compressive strength of concrete and erode the structure.
Indirectly, the tensile strength is also affected as the tensile strength is based on the concrete materials to some extent.
Given below, some of the vital factors which can directly or indirectly impact the strength of the concrete.
Permeability of the Structure:
If the structure is permeable, the water and different types of chemicals like acid rains, and sulfate can easily penetrate through the structure and consequently, the binding of the concrete material becomes weak.
So, the design of the concrete should be made in an efficient manner to reduce its permeability and stop the entering of the liquid from outside into the structure.
Alkali-Silica Reaction:
Alkali-Silica Reaction (ASR) belongs to the expansive chemical reactions with the existent chemicals in the concrete mixture.
Lots of Silica exist in the aggregate of concrete, whereas potassium and sodium alkalis exist in cement paste.
The silica of aggregate creates a reaction with potassium and sodium of cement. This reaction leads to an expansion in the concrete as well as forms a network of cracks, spalling of joints, and movement of specific portions of the structure.
The strength of the concrete structure is significantly reduced due to these reactions.
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Sulfate in Water:
Lots of sulfates prevail in water and soil. The sulfate of soil and water creates a reaction with the sodium and calcium of binding material (cement), as a result, Calcium Sulfate and Sodium Sulfate are produced.
The Sulfate causes the disintegration of concrete structure in the seashore and other areas. If the structure contains sulfate, it creates on the concrete structure and leads to degeneration.
Effect of Freeze-Thaw Cycle on Concrete:
The Freez-thaw cycle can also decrease the strength of the concrete. On a freezing, the existent water within the pores and cracks of the structure extends and creates pressure on the walls of the pores and cracks. It makes the cracking of the structure bigger.
Because of the high temperature, the ice and snow are melted and it is known as a thaw. The existent ice within the pores and cracks of the concrete structure is melt, and decreases its volume, as a result, the water is accumulated inside the spaces of the pores and cracks.
At night, the temperature is reduced significantly and the existent water within the pores again freezes and extends its volume to create extreme pressure on the walls/sides of the cracks, consequently, the structure is weakened.
Abrasion Resistance of the Concrete:
Due to friction & scratching, the resistance power of a surface is eroded and it is called abrasion.
It is entirely based on the durability of the concrete, exposure conditions, properties of aggregate, binder (cementing material), surface finishing, and the curing method.
So, it is necessary to take proper precautions to If the above precautionary steps are not taken, the erosion can erode the structure quickly.
Due to erosion, the reinforced material also erodes the concrete cover. The reinforcing bars have the ability to keep the structure stronger when they are firmly covered in the concrete.
