What Is the Durability Of Concrete?
What Is the Durability Of Concrete?
Concrete’s durability refers to its ability to withstand various destructive forces, such as weathering, chemical attacks, and abrasions, while maintaining its desired structural properties.
The specific requirements for durability will vary depending on the intended use and exposure environment of the concrete, with concrete intended for outdoor use in a marine environment having different requirements than indoor concrete.
Durability is often associated with the lifespan of concrete and its ability to perform without issues.
Durability is an important characteristic of concrete, as it determines the ability of the material to withstand various forms of damage such as weathering, chemical attack, and abrasion while maintaining its desired engineering properties.
The durability of concrete is influenced by a range of factors, including the type and proportion of ingredients used, the placing and curing methods, and the service environment.
Concrete is generally resistant to humidity, ultraviolet radiation, and vermin and insects, but it can be vulnerable to freezing and thawing, salt attack, and alkali-silica reaction.
The design service life of concrete structures is usually 30 years, although they often last much longer.
In order to ensure the durability of concrete, it is important to consider the relevant exposure conditions and deterioration mechanisms, and to select appropriate materials and mix design parameters.
How Do You Find The Durability Of Concrete?
Concrete is a durable material that can withstand weathering, chemical attack, and maintain its desired engineering properties.
However, poor construction practices, insufficient curing, and improper mix designs can lead to premature deterioration in structures, which is a global problem that costs billions of dollars each year.
To ensure the durability of a structure, it is important to consider a variety of factors, including a proper mix design.
One way to quantify the durability of a mix is to reduce the permeation of water into the concrete.
There are several tests that can be used to measure the permeability of concrete, including water absorption, surface absorption, water permeability, and chloride permeability.
The water absorption test, such as the BS1881 part 122 test, measures the water absorption by an immersed sample and is more relevant for applications where concrete is exposed to low or no hydrostatic pressure.
The permeability test, such as the BS12390/DIN1048 test, measures the resistance of concrete to the penetration of water under hydrostatic pressure and should be considered for situations where concrete is subjected to hydrostatic pressure.
The chloride permeability test, such as the ASTM 1202-RCP test, measures the ability of concrete to resist chloride ion penetration, but it is not always a reliable indicator of concrete durability.
In addition to permeability, the tendency of concrete to crack can also impact its durability, although this property is often overlooked.
Because concrete can be exposed to a variety of different environments, it is important to use a range of test methods to evaluate its durability.
Is Bulk Electrical Resistivity A Reliable Test To Determine The Durability Of Concrete?
Electrical resistivity is a faster and more affordable method for evaluating the quality and longevity of concrete.
It measures the concrete’s ability to resist the flow of electricity or the passage of chloride, which allows for the assessment of the concrete’s quality control and prediction of its service life.
The resistivity reflects the concrete’s permeability to fluids and its durability, particularly in relation to corrosion caused by chloride penetration.
The microstructure of the concrete, such as its porous network and interconnections, plays a significant role in its durability.
Concrete with low porosity and interconnections has lower conductivity and permeability. Electrical resistivity quantifies the conductive properties of concrete and can be used in both laboratory and field settings.
It can be used to compare changes in the mix design, such as modifications to the cement or the addition of other materials, by comparing resistivity values from lab specimens with field samples.
It can also be correlated with other characteristics, such as the chloride diffusion coefficient, water absorption, and corrosion rate of rebar in reinforced structures, to provide a quantitative assessment of the concrete’s condition.