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
Angularity Number Angularity number is used to give an indication of shape of aggregate. The concept of angularity number was suggested by Shergold. It gives a qualitative representation of shape of aggregate. Angularity Number Test Angularity number test gives an idea of how angular the aggregate is. This is based on the percentage of voids … 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
To describe an aggregate by its maximum and minimum size is not sufficient. It has to be graded from its minimum to maximum size. IS-383 recommends the following grading limit for fine aggregates. Grading Limits For Fine Aggregates Sieve Size Percentage of Passing For Grading Zone-I Grading Zone-II Grading Zone-III Grading Zone-IV 10 mm 100 … Read more
The grading of coarse aggregate may be varied through wider limits than that of fine aggregates, since it does not affect the workability, uniformity and finishing qualities of concrete mix. As per IS-383 the grading limit of coarse aggregate, both for single size as well as graded should be as per the table given below. … Read more