Grading Limit of All in Aggregate Sieve Size Percentage of Passing For All-in-Aggregate 40 mm Nominal Size 20 mm Nominal Size 80 mm 100 – 40 mm 95 – 100 100 20 mm 45 – 75 95 – 100 4.75 mm 25 – 45 30 – 50 600 micron 8 – 30 10 – … Read more
What is Fineness Modulus of Aggregate? Fineness modulus is an empirical factor obtained by adding the cumulative percentages of aggregate retained on each of the standard sieves ranging from 80 mm to 150 micron and dividing this sum by 100. Why to Determine Fineness Modulus? Fineness modulus is generally used to get an idea of … Read more
Our aim is to mix the fine aggregate & coarse aggregate in such a ratio so that the final combined aggregate gives the specified or desirable surface index. Follow the below mentioned steps to find the proportion of fine to coarse aggregate. Procedure Calculate the total surface index of fine aggregate (let it be x) … Read more
Total Surface Index of Aggregates In my previous post I discussed about surface index of aggregate for individual aggregate grading. But in actual practice we use combination of different aggregates having different sizes. So now the question that comes to our mind is whether we can represent surface index of mixed aggregates or not. The … Read more
Surface Index of Aggregates Surface index of aggregates is another way to represent the specific surface of aggregate. This method was suggested by Murdock. Murdock provided some empirical numbers to represent the specific surface of different aggregates grading (as shown in the table below). Surface Index Values for Different Aggregate Grading Sieve Size Within Which … Read more
Specific Surface of Aggregate The surface area per unit weight of the material is termed as specific surface. This is an indirect measure of the aggregate grading. Specific surface increases with the reduction in the size of aggregate particle. The specific surface area of the fine aggregate is very much more than that of coarse … Read more
Which One Is Better For Concrete-Rounded or Angular Aggregate Angular aggregate are superior to rounded aggregate from the following two points of view. Angular aggregate exhibit a better interlocking effect in concrete, which property makes it superior in concrete used for roads and pavements. The total surface area of rough textured angular aggregate is more … Read more
Aggregate impact value test gives an indication of aggregate’s toughness property (i.e. property of a material to resist impact) Aggregate impact values are used to classify the stone aggregates with respect to toughness property as given below. Aggregate impact value (%) Toughness Properties <10 Exceptionally tough / Strong 10 – 20 Very tough / Strong … Read more
According to size the aggregates are classified as: Fine Aggregate Coarse Aggregate All in Aggregate Fine Aggregate It is the aggregate most of which passes 4.75 mm IS sieve and contains only so much coarser as is permitted by specification. According to source fine aggregate may be described as: Natural Sand– it is the aggregate … Read more
One of the first field investigations for a concrete construction project is to search for sources of aggregates which will give material of good quality at economical rates. Suitability of aggregate will depend upon the geological history of the region. The aggregate as per nature of formation may be divided into two types. Natural Aggregates … Read more