Concrete Mix Design

Concrete Mix Selection or Mix Design

The extensive use of concrete as construction material has lead to the use of mixes of a preset proportion, in places where there is no proper batching system and site control, and the preset ones gives a satisfactory strength. These mixes are called nominal mixes. They are simple and under normal circumstances, will give a strength just little above that specified.

But Nominal mix concrete has various limitations like, High consumption of cement, No scope of inputs for durability parameters, impractical of adjustments after Gradation of All in aggregate , Difficulties in attaining cohesive and workable mixes , limited to low grades, not suitable for Ready-mix concrete ,and other special concretes like High performance ,self compacting, lightweight etc. Considering above issues, a need arisen to Design a Concrete Mix to suit the various, types, Strength, Quality, and durability requirements and the international community worked out various methodologies to arrive the same.

Concrete mix design/Mix Selection is the process of selecting suitable ingredients of concrete and determining the relative quantities with the object of producing as economically as possible concrete of certain minimum properties, namely, consistence, and strength and durability-Adam neville

Various Methods of Concrete Mix Proportioning

• American Concrete Institute Method of Mix Design (ACI 211)
• British Research Establishments- Design of Normal Concrete Mixes Method
• Indian Road Congress , IRC 44 method & IS 10262 Method

Basic Considerations

• Cost-Plays vital role which decides the proportion
• Specification-The proportion are to be made according to the required specifications
• Workability-The Concrete mix to be workable such that it should be poured in ease
• Strength and Durability-The main purpose of the mix proportion

Meaning of C & 30 of a Concrete Type C30

•C refers to Mix Grade
• And 30 refers to characteristic compressive strength of a 150 mm cube at 28 days in N/mm2

Important Factors Influencing Choice of Mix Design

• Grade of Concrete-Which gives Characteristic Compressive strength
• Type of Cement-Cement type has a great influence in Strength, Durability and the Need of concrete type
• Size of Coarse Aggregate-Big/Optimum Size gives High strength
• Grading of Combined aggregate-Gradation Gives Cohesive and workable mix
• Water/ Cement Ratio-Low and Optimum Water Cement ratio will give good strength
• Workability- Measurable Parameter indicates the nature of concrete mixture for, transportation, placement, compaction and finish without harmful segregation and bleeding.
• Durability-Plays a Vital role in selecting cement, Aggregate proportion and Special Additions
• Quality Control-According to degree of control the Target mean strength differs and the need of cement Content.

Concrete Mix Design now provides an easy, fast way to arrive a Proper Concrete Mix selection. The app with various additions allows you to create proportions of the mix design using the absolute volume method and we can get the results both in weight and volume basis. Also the app has Standard deviation calculation of Concrete mixes and Gradation calculations of individual aggregate and All in Aggregate.
The application executes all the calculations in SI units, according to the BRE standard and its guidelines. Once the concrete mix design is complete, the app generates a Mix design sheet which can be printed and shared.