VOLUME BATCHING OF CONCRETE –THEORY & EXAMPLE CALCULATION Suryakanta | June 17, 2016 | Building Construction, Concrete, Concrete Technology, Construction, How To, Materials, Road Construction | 4 Comments What Is Volume Batching of Concrete? Batching of concrete means measuring different ingredients of concrete (i.e. cement, sand, coarse aggregate and water) before mixing it. When this measurement is done on the basis of volume, we call it Volume Batching. Below are mentioned some of important points to remember before adopting volume batching method in field. Volume batching is not a good method for measuring concrete materials. It is not applicable in case of reinforced concrete structure. This method of concrete batching may not be economical. It can be only used for unimportant concrete or for small concrete works. How Volume Batching Is Done In Field? Before batching concrete ingredients in terms of volume, we need to know two things. 1. What is the relative proportion of concrete ingredients in terms of volume? 2. What is the water-cement ratio? After knowing these two things you can proceed to batch concrete ingredients in field. The table shown below can be used as a reference to find out relative proportion of different ingredients, for different grades of concrete. Grade of Concrete M 10 M 15 M 20 M 25 Relative Proportion of Ingredients by Volume Fine Coarse Cement Aggregate Aggregate 1 3 6 1 2 4 1 1.5 3 1 1 2 In General We Specify It As 1:3:6 1:2:4 1:1.5:3 1:1:2 The water-cement ratio to be used must be as per the contract. It should be completely filled with aggregates. 0. 35 litres). The box should not be too shallow.035m3). The following table gives the approximate surface moisture carried by aggregates as per IS456-2000.e. One bag of cement weighs 50 kg and has a volume of 35 litres (or. Inside Dimensions of gauge Capacity In box in cm Litres Length Breadth Depth 25 25 25 40 30 25 25 48 35 27 27 48 40 29 29 48 45 30 30 50 50 31 31 52 Note: The moisture present in aggregates and bulking of sand must be accounted for while volume batching is adopted. The ratio of materials of concrete decides the capacity of the box. Mostly it is used in terms of bags. Convenient sizes of gauge boxes to suit different proportions are given in the table below. Cement should not be batched by volume because its weight per unit volume varies according to the way the container is filled. Generally capacity of a gauge box is equal to the volume of one bag of cement (i. Step-2-Batching of aggregate (by volume) Gauge Box A gauge box is used (as shown in the picture) for batching of fine and coarse aggregate by volume. Condition of Aggregates Approximate Quantity of Surface Mositure Percent by Litre per m3 Mass .Step-1-Batching of cement Cement is always measured by weight. The top of the materials should be struck off level with a straight edge. the two units are same.A. as the density of water is one kg per litre. so that you become more confident in the field. =70*(6/100)=4.) =1.Very wet sand Moderately wet sand Moist sand Moist gravel or crushed rock 7.A.6 Moisture content in fine aggregate (i.5% by volume Bulking of fine aggregate is 20% Solution Step-1-Calculating Volume of Dry material Required Ratio of materials by volume =1:2:4 Volume of one bag of cement =35 litres Volume of dry fine aggregate required =35*2=70 litres Volume of dry coarse aggregate required =35*4=140 litres Water-cement ratio =0.3 litres F.5% Amount of moisture present in C. In this case.A & =4. .) =6% Amount of moisture present in F.60*50=30 litres Step-2-Applying Correction for Moisture Present in Aggregate Moisture percent in fine aggregate (F.25-2. Example Calculation Now let us solve an example.5 1.A.2+2.0 2.e.1 litres So extra amount of moisture present in C. =140*(1. The quantity of water required is calculated by multiplying water-cement ratio with weight of cement.5/100)=2. sand) is 6% by volume Moisture content in coarse aggregate is 1. Data Given Relative proportion of cement : sand : coarse aggregate is 1:2:4 Water-cement ratio is 0.A. how correction for bulking is applied and how correction of any surface moisture is applied.1=6.60 Total water required =0.2 litres Moisture percent in coarse aggregate (C. In this example I have also tried o show you.A.5 5.5 120 80 40 20-40 Step-3-Batching of water Water is measured either in kg or litres as may be convenient. =Total water-extra amount of water present as moisture content=30-6.A.3 Net water to be added =23.=70*(20/100) Bulking of fine aggregate Moist fine aggregate required =14 litres =70+14=84 litres .7 litres Step-3-Applying Correction for Bulking of fine aggregate =20% of total volume of F.