Design a concrete mix for the following performances and ingredients: • Compressive strength at 28 days = 32 MPa, slump 80 mm • Crushed coarse aggregate of max size 20 mm readily available • Fine aggregate is river sand, fineness modulus = 2.5 • Specific gravity of combined aggregate =2.6 • Water absorption of fine aggregate = 0.5% • Water absorption of coarse aggregate = 0.8% • Air-dry moisture content of coarse aggregate = 0.2% • Air-dry moisture content of fine aggregate = 0.4%
Design a concrete mix for the following performances and ingredients:
• Compressive strength at 28 days = 32 MPa, slump 80 mm
• Crushed coarse aggregate of max size 20 mm readily available
• Fine aggregate is river sand, fineness modulus = 2.5
• Specific gravity of combined aggregate =2.6
• Water absorption of fine aggregate = 0.5%
• Water absorption of coarse aggregate = 0.8%
• Air-dry moisture content of coarse aggregate = 0.2%
• Air-dry moisture content of fine aggregate = 0.4%
Note: the constant k used to find the margin, which is in turn used to determine the target compressive strength is as shown the table below:
k for 10 % defectives = 1.28
k for 5% defectives = 1.64
k for 2.5% defectives= 1.96
k for 1% defectives= 2.33
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