Post on 28-Jul-2015
Concrete Mix Design
By Abhishek Khandelwal
Introduction
• Concrete Mix Design means, determination of the proportion of the concrete ingredients i.e. Cement, Water, Fine Aggregate, Coarse Aggregate which would produce concrete possessing specified properties such as workability, strength and durability with maximum overall economy.
Types of Concrete Mixes1. Nominal Mixes – • These mixes are of fixed cement-aggregate ratio. • These offer simplicity and under normal circumstances.• Have a margin of strength above that specified.
2. Standard Mixes – • The minimum compressive strength has been included by IS-
456:2000 in many specifications. These mixes are termed standard mixes.
• E.g.: M10, M15, M20, etc.
3. Designed Mixes -• In these mixes the performance of the concrete is specified by the
designer but the mix proportions are determined by the producer of concrete, except that the minimum cement content can be laid down.
Methods of Concrete Mix Design
• American Concrete Institute Method (ACI Method)
• Road Note Number 4 Method• DOE Method• Indian Standard Method (IS Method)
Indian Standard Recommended Method Of Concrete Mix Design
(IS 10262 - 2009)
Data Required:• Grade of Concrete• Slump required in mm• Degree of Site Control• Type of Exposure• Grade of Cement
Workability (Clause 7.1, IS:456-2000)
Degree of Site Control(Table 8, IS:456-2000)
Type of Exposure (Table 3, IS:456-2000)
Concrete Mix Design steps
IS - 10262 : 2009
Step1 Target Mean Strength
• Target mean strength
ft = fck+ k x s
ft = 30+1.65 x 5
ft = 38.25 N/
ft = target mean compressive strength at 28 days
fck = Characteristic compressive strength of concrete at 28 days,
k = usually 1.65 as per IS:456-2000
s = standard deviation.
Step2 Selection of water/cement ratio• Using graph
= 0.38
Step2 Selection of water/cement ratioBut from table – 5, IS-456:2000
Step2 Selection of water/cement ratio
Considering moderate exposure,
Max w/c = 0.5
Hence w/c = 0.38
w/c = 0.38
Step3 Selection Of Water Content.
• From table – 2, IS-10262:2009
(For 20mm nominal max. size of aggregate & 25 to 50mm slump)
Max WC = 186 kg/m3
# Correction for slump in water content (according to clause 4.2, IS:10262)
Slump = 100 mm
Correct WC for 100 mm slump = 186 + 6%
= 197.16 kg
197 kg of water per m3 of concrete
Step4 Calculation Of Cement Content
W/C = 0.38
C = = 518.42 kg/m3
Min CC = 300 kg/m3 concrete
(From table: 5, IS:456)
Hence, C = 518.42 kg/m3
518.42 kg of Cement per m3 of Concrete
Step 5: Selection of Proposition of Volume of Coarse Aggregate
From table 3,(IS-10262:2009) for zone IIIrd of F.A.
Maximum size of aggregate = 20 mm.
Vol. of CA per unit vol. of total aggregate = 0.64
# For 0.1 decrease in w/c & increase in CA by 0.02
Applying correction of 0.024
Vol. of CA = 0.64 + 0.024
=0.664m3
Total aggregate = 1
CA = 0.664m3
FA = 0.336m3
Step6 Mix Calculation Results:
Mass of Cement
Water F.A. C.A.
518.42 197 586.36 1161.76
1 0.38 1.13 2.24
Ratio Obtained
1 : 1.13 : 2.24
Thanks For
Hearing