Saturday, 10 March 2018

High Density and High Strength Concrete

High Density Concrete

                                        The concrete whose density varies from 3360 to 3840 kg/m3 is known as high density concrete . However they can be produced with densities up to 5280 kg/m3  using iron both fine and coarse aggregates.The high density concrete is produced using the aggregates having specific gravity more than 3.5 .The commercially used aggregates are barite , magnetite, ilmenite, limonite etc . Steel and iron aggregates are also used to produce high density concrete. 

The grout used in this concrete should be richer than that used in normal concrete.Extra care must be taken with respect to segregation of heavy aggregates from the rest of the ingredients. The form work should be made stronger to withstand high load. 
The high density concrete is widely used in the construction of radiation shields in nuclear industry.


High Strength Concrete

                                          As per I.S recommended method of mix design , a concrete is said to be high strength concrete if its strength is more than 35 M.Pa . In the modern batching plants high strength concrete is produced mechanical manner. For production of high strength concrete due care should be taken about mix proportion shape of aggregates, use of supplementary cementitious materials, super plasticizers etc.
The special method adopted for making high strength concrete are
a)Seeding
b)Re-vibration 
c)High speed slurry 
d)Use admixtures
e)Inhibition of cracks 
f)Sulpher impregnation etc.

High strength concrete is generally used for construction pre-stressed concrete bridges, flyovers , high rise building, power project and other works of greater importance.
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