Concrete Mix Design
Select the type of concrete
Description Mix Design can be defined as the process of selecting suitable ingredients of concrete and determining their relative proportions with the object of producing concrete of certain minimum strength and durability as economically as possible.Types of mix: 1. Nominal mix: In the past the specifications for concrete prescribed the proportions of cement, fine and coarse aggregates. These mixes of fixed cement-aggregate ratio which ensures adequate strength are termed nominal mixes. 2. Standard mix: The nominal mixes of fixed cement-aggregate ratio (by volume) vary widely in strength and may result in under- or over-rich mixes. For this reason, the minimum compressive strength has been included in many specifications. These mixes are termed standard mixes. 3. Design mix: 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. This is most rational approach to the selection of mix proportions with specific materials in mind possessing more or less unique characteristics.Concrete Grade:
Exposure Condition:
Aggregate Size:
Slump:
Concrete Placing:
Calculate the target strength for mix proportioning.
Characteristic strength The characteristic strength is defined as the strength of the concrete below which not more than 5% of the test results are expected to fall.
Target strength for mix proportioning, Fck = fck+1.65(S) N/mm2
Target strength for mix proportioning = ✔
Calculate the Water Cement ratio.
Calculate the water content.
Addition of super plasticizers reduces Water Content upto 20% and above.
Calculate the cement content.
Cement content (kg/m3)= Water Content⁄Selected W/C Ratio
Cement content = ✔
Calculate the volume of coarse aggregate and fine aggregate.
- Volume of coarse aggregate corresponding to 20mm size and fine aggregate of Zone I for w/c 0.5=0.6
- If w/c is less than 0.5 then volume of coarse aggregate is to be increased to decrease the fine aggregate content at the rate of ±0.01 for every ±0.05 change in w/c ratio
- If method of concrete placing is Pumping, then Volume has to be reduced by 10%
= m3✔
Mix calculations:
Variables used in calculations- Specific gravity of Cement = 3.15
- Specific gravity of Water = 1
- Specific gravity of Admixture = 1.145
- Specific gravity of Fine Aggregate = 2.7
- Specific gravity of Coarse Aggregate = 2.74
a) Volume of Concrete = 1m3
b) Volume of Cement =m3✔
Volume of Cement = Mass of Cement⁄Specific gravity of Cement x 1000c) Volume of Water =m3✔
Volume of Water = Mass of Water⁄Specific gravity of Water x 1000d) Volume of Admixture =m3✔
Volume of Admixture = Mass of Admixture⁄Specific gravity of Admixture x 1000e) Volume of all in aggregate =m3✔
Volume of all in aggregate = a - ( b + c + d )f) Mass of Coarse Aggregate =kg✔
Mass of Coarse Aggregate = e x Volume of Coarse Aggregate x Specific gravity of Coarse Aggregate x 1000g) Mass of Fine Aggregate =kg✔
Mass of Fine Aggregate = e x Volume of Fine Aggregate x Specific gravity of Fine Aggregate x 1000Mix Proportion:
