Jayant Kulkarni SEFI Member
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Joined: 28 Feb 2012 Posts: 6
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Posted: Fri Mar 02, 2012 7:01 pmPost subject: Service life assesment--durability of concrete in buildings |
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Dear All,
很多研究文献报道评估ment of service life of concrete based on mathematical modelling involving various parameters. In all these studies, the most important parameter affecting service life is considered as `rate of chloride penetration`which is expected to affect the initiation of corrosion.
Of course, it is indeed the most important factor for those structures with marine environment or where deicing salts are used in cold countries. Also, it is predominantly applicable for the structures made in concrete alone like bridges etc.
But actually, large quantity of concrete is used in the buildings in which the concrete is invariably protected by some kind of cladding and coatings ( mostly plaster and paint at least in India) . Also, in majority of the area in India( except coastal area which is not more than 10-15%), chlorides in the atmosphere is not a major issue. In all these cases, it is difficult to apply the mathematical modelling based on rate of chloride penetration alone. Are there any guidelines available for such structures?
In my opinion, the following are going to be the important parameters ( apart from the quality of concrete itself) in formulating such guidelines:
1) The thickness and quality of protection available to concrete. 2) The level of maintainance of the building. 3) The difference between the max. and min. temperature, as over the years, this is expected to be the main cause of surface cracking in plaster as well as concrete. 4)振动/疲劳载荷的影响。 5) The quality and detailing of joints between concrete and masonry. 6)交货posure of building part/concrete element to rain and the intensity of rain itself, as severe rain washes away the loose particles. 7) Exposure of building part/ concrete element to wind and the wind intensity, as strong winds also take away the loose particles and widen the cracks. 8) The location of concrete element, whether in dry area or wet areas like bathroom and water closets. 9) And finally, the rate of carbonation penetration, which is indirectly the permeability of concrete again.
Although it may be very difficult to incorporate all the above parameters in any mathematical modelling , but some kind of qualitative guidelines can be formulated in the form of charts or grading incorporating all the above parameters, which can give the estimate of the magic figure of `service life` of a particular structure.
Jayant Kulkarni Consulting Structural engineer |
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