The durability of concrete has been of considerable scientific and technological interest over the last few decades.
A durable concrete is one that performs satisfactorily and retain original form, quality, and serviceability when exposed to different weather conditions.
Durability of Portland cement concrete is defined as its ability to resist weathering action, chemical attack, abrasion, fire or another process of deterioration. In other words, cement concrete will be termed durable, when it keeps its form and shape within the allowable limits to different environmental conditions.
Because of the above scientist and engineers across the globe are working very hard in search of different mechanism and admixtures to improve this particular aspect of concrete.
Once concrete looses its durability it also looses its strength and ultimately affects the life/integrity of the structure.
Durability of Concrete depends on the following factors: Aggregate Type, Cement Content, Water-Cement (W/C) Ratio, Cement Type, Air Entrainment, Carbonation Process, Quality of Mixing Water, Influence of Crack, Depth of Cover to the Reinforcement, Age of Immersion, Diffusion of Salts Under Pressure, Wetting and Drying Cycles, Freezing and Thawing Cycle
Dear Saleh
Durability is vital with regards to a structure's lifespan. It is the characteristic that dictates how long a structure can live to perform its desired function. Therefore it has a direct impact on strength. It cannot be underestimated. The durability is about the ability of the structure to resist action from the weather over time, fire, and any chemical attack, while maintaining the desired engineering properties. So, it is really vital.
That is why much research has been undertaken and still continuing to improve the durability of cement concrete. Also, the technology of concrete maintenance and repair is all aimed at extending the concrete lifespan, and hence improving its durability.
On top of the answers above, I would say that the importance of durability has been highlighted due to the aging of existing structures. This is particularly true for developed countries where the construction of infrastructures started about 50+ years ago. In the case of developing of countries, the focus is more (not that they are not concern) on building new infrastructures, i.e. there are less structures to maintain. And since the number of researchers from these developed countries are higher than developing countries, the importance of durability is foregrounded- which I believe is essential.
Concrete is termed durable when it keeps its form and shape within the allowable limits when exposed to different environmental conditions. The durability of concrete has been a major concern of civil engineering professionals. In addition, it has been of considerable scientific and technological interest over the last few decades. The effect of seawater on concrete deserves special attention because sea structures are exposed to the simultaneous action of chemical deterioration processes. Concrete exposed to seawater may deteriorate as a result of the combined effects of the chemical action of seawater constituents on cement hydration products and the corrosion of reinforcing steel.
"Durability of concrete may be defined as the ability of concrete to resist weathering action, chemical attack, and abrasion while maintaining its desired engineering properties". Response to the severity of the atmospheric/environmental conditions, safety of the reinforcement and the structural performance of any structure are primarily the function of the durability. The durability defines the endurance of concrete to resist the various undulating factors responsible for deterioration of the concrete and possibly the reinforcement resulting in weakening of the structure consequently. This is just a gist of the whole idea. For detailed study, please check the following:
http://www.cement.org/learn/concrete-technology/durability
http://onlinepubs.trb.org/onlinepubs/circulars/ec171.pdf
Dear Dr. Debasish Mondal
I completely agree with your answer which states that, the durability of Portland cement concrete is defined as its ability to resist weathering action, chemical attack, abrasion, fire or another process of deterioration. In other words, cement concrete will be termed durable, when it keeps its form and shape within the allowable limits to different environmental conditions.
All the best Regards Sincerely Yours, Prof. Dr. Saleh Abd El-Aleem Mohammed (Applied and Engineering Inorganic Chemistry) Vice-Dean Faculty of Science, Fayoum University, Fayoum, Egypt [email protected]
Many scientists and engineers are now looking for the right key for designing sustainable infrastructure systems that show higher durability and have a long maintenance-free performance with low repair costs. From the materials point of view, the effort to increase the service life of infrastructure can be made by using various advanced high-quality materials, including the newly emerging concepts of multifunctional structural and durable materials. One material that is undergoing such advancements is concrete.
Dear Dr. Saleh, To improve the capability of concrete to resist weathering action, chemical attack and abrasion while maintaining its desired engineering properties. It normally refers to the duration or lifespan of trouble-free performance. Different concretes require different degrees of durability depending on the exposure environment and properties desired. For example, concrete exposed to tidal seawater will have different requirements than indoor concrete. Best Wishes
The design life of any concrete structure member is always greater than 30 years. It is expected that in this span of time the important parameters such as compressive strength and flexural strength would resist the external and internal stresses arising due to loading and environmental changes. However, if any of the aforesaid condition (lower strength or higher loading condition) changes it may reduce the service life of the concrete significantly.
Almost all the structural concrete members are designed based upon their compressive strength whereas in case of concrete pavements, flexural strength is considered to be the design factor. The determination of compressive and flexural strength of aforesaid members is generally done in laboratory conditions at 28 days of moist curing. However, in actual site conditions, this ideal condition may or may not sustain which may reduce these important parameters. Moreover, two structural members with same compressive strength may behavior differently in same environmental conditions (owing to difference in voids configuration).
Due to aforesaid, the durability properties such as resistance to acidic environment, water absorption, abrasion resistance etc are always ascertained before designing the same based upon compressive and flexural strength.
Prof. Dr. Doha M Al Saffar
Your comment is very logic and interesting. I completely agree with you
Yes, all the structural concrete members are designed based upon their compressive strength whereas in case of concrete pavements, flexural strength is considered to be the design factor. The determination of compressive and flexural strength of aforesaid members is generally done in laboratory conditions at 28 days of moist curing. However, in actual site conditions, this ideal condition may or may not sustain which may reduce these important parameters. Moreover, two structural members with same compressive strength may behavior differently in same environmental conditions
Dear Surender Singh,
You are right, but the concrete mix design by ACI method and British method have limits for minimum compressive strength, maximum W/C ratio and type of used cement for the durability under environmental exposure conditions or sulfate attack. So, if you want to design a concrete mix you must take the surrounding environmental and durability to your consideration. Finally, we assume the ideal condition and deal with the durability at mix the design, except at some points of research we assume the attacking environment to investigate the reaction of concrete.
Kind regards,
because it's can join in active ingredients such as fine and aggregate. Also, hydration process lead to generate alkaline media (PH almost 12 to 13), so that, the steel reinforcement protected against rust. By the way, the new generation of geopolymer will achieve green concrete without any loss of traditional concrete benefits
The durability of concrete has been a major concern of civil engineering professionals. In addition, it has been of considerable scientific and technological interest over the last few decades.
The effect of seawater on concrete deserves special attention because sea structures are exposed to the simultaneous action of chemical deterioration processes. Concrete exposed to seawater may deteriorate as a result of the combined effects of the chemical action of seawater constituents on cement hydration products
First of all concrete is durable thats why it is widely used construction material, Durability is the ability of concrete to sustain all the types foreign agencies which comes in contact with concrete in its life span, the concrete which resist all the attacks from nature and made made hazards can be termed as Durable Concrete.
Coming to the question why durabilty of concrete has become major concern for civil engineers. it is because the climatic change which is happening at a faster rate, concrete is getting affected by the man made hazards rather than natural effect. For example: Industries leaving their exhausts contain large number of impurities which will have impact on concrete structures slowly, industries leaving their effluents in water will have impact on concrete structures which are built in water which already has to fight with chloride content in water. There are many issues which we as a civil engineer have to concentrate on durabilty of structures to protect from harmful chemicals which come in contact directly or indirectly on concrete structure, todays durability analysis have to be done rigorously compared to 50-60 years ago. Because of all these issues durabilty concept has gained more importance of scientific and technological interest
Regards...
Abhijeet Baikerikar
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