Therefore the total dry volume of the cement+sand + aggregate needed to prepare concrete should be more than the total volume of concrete. While mixing the ingredients, cement and sand will first fill the gaps between the coarse aggregate before taking their own space. Method:1 Calculation of Cement, Sand and Aggregate from Nominal mix ratio Method 2: Calculating the weight of sand and aggregate required per 50kgbag of cement using the Total weight of aggregate value given in the IS codebook.Method 1: Calculating cement, sand and coarse aggregate required in volume, and in weight from prescribed Nominal Concrete Mix Ratio.Hence it is not advisable to increase the fine aggregate content (river sand or M sand) more than 30% from the prescribed ratios in any case.Įngineers follow two simple ways to easily calculate cement, sand and aggregate needed to prepare concrete But, excess modification in sand and cement content will adversely affect the strength of concrete. For example, they may increase the sand content to increase the workability of concrete, or reduce the cement content to decrease the cost of concrete. However, sometimes, engineers might modify the above ratios based on their requirements. Design Mix ratios are in weight and they are used to prepare concrete in larger batches in places like RMC plants for ready mix concrete Nominal Concrete Mix Ratio for Different Grades of Concrete Concrete Grade Since Nominal Mix ratios are in volume and easy to follow, they are used in the construction sites to prepare different grades of concrete in concrete mixers. Nominal Mix ratios are prescribed concrete Mix ratios to get different grades of concrete, whereas Design Mix ratios are calculated through the Design mix procedures from IS10262 codebook. Difference between Nominal Mix Ratio and Design Mix Ratio
For example, the prescribed Nominal concrete mix ratio of M20 concrete is 1:1.5:3, hence for every 1 part of cement, 1.5 parts of sand and 3 parts of aggregate, in volume, is needed to prepare M20 grade concrete.
What is Concrete Mix Ratio?Ĭoncrete mix ratio is a relative proportioning of cement, sand, aggregate and other materials needed to prepare different grades of concrete. For example, M20 grade concrete will achieve its compressive strength of 20 N/mm 2 in 28 days after curing in water.