Wednesday, August 31, 2016
Mix Design On The Basis Of Dry Condition
Ascertain or Identify Slump Value
The initial step is to identify the lowest and highest limit for slump of concrete that has been utilized. Often the designer identify slump for concrete mix, this is correctly based on some conditions, otherwise if the value of slump is not indicated Table 1 is applied to find out the lowest and highest slump value on the basis of the type of structure.
Note: The value of (Table 1) is dependent on applying vibrator for compaction of concrete, if there is other method for compaction like a tamping by rods or other method add (2 cm) for every selected value from table 1.
Step 2: Ascertain or State Maximum Aggregate Size
Highest Aggregate Size is considered as the most vital data to be ascertained or identified for their mix design. This value is acquired from sieving analysis test result of coarse aggregate. Coarse aggregate must be examined prior to utilize in concrete mixture preparation. This value is accessible even for comprehensive mix design process.
Value of Maximum Aggregate Size must be examined with the following three equations:
(a): Highest Aggregate Size must be identical or lesser than 1/5 (lowest distance among form work side).
(b): Highest Aggregate Size must be identical or lesser than 1/3 (thickness of concrete member).
(c): Highest Aggregate Size must be identical or lesser than 3/4 (slightest distance among reinforcement).
Note: Point (c) is very vital in checking process as if the aggregate size exceeds the spacing of reinforcement while casting, concrete fails to pass the rebar cage. It signifies that passing ability of concrete is considerably reduced.
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