ANY NATURAL SAND PARTICLES WON FROM THE LAND THROUGH THE MINING PROCESS
When the aggregate is sieved through a 4.75mm sieve, the aggregate passed through it called fine aggregate. Natural sand is generally used as fine aggregate, silt and clay also come under this category. The soft deposit consisting of sand, silt, and clay is termed as loam. The purpose of the fine aggregate is to fill the voids in the coarse aggregate and to act as a workability agent.
We know that aggregate is derived from naturally occurring rocks by blasting or crushing etc., so, it is difficult to attain required shape of aggregate. But, the shape of aggregate will affect the workability of concrete. So, we should take care about the shape of aggregate. This care is not only applicable to parent rock but also to the crushing machine used.
Aggregates are classified according to shape into the following types
(i) Rounded aggregates
(ii) Irregular or partly rounded aggregates
(iii) Angular aggregates
(iv) Flaky aggregates
(v) Elongated aggregates
(vi) Flaky and elongated aggregates
(i) Rounded aggregates :
The rounded aggregates are completely shaped by attrition (the resistance of a granular material to wear) and available in the form of seashore gravel. Rounded aggregates result in the minimum percentage of voids (32 – 33%) hence gives more workability. They require a lesser amount of water-cement ratio. They are not considered for high-strength concrete because of poor interlocking behavior and weak bond strength.
The irregular or partly rounded aggregates are partly shaped by attrition and these are available in the form of pit sands and gravel. Irregular aggregates may result 35- 37% of voids. These will give lesser workability when compared to rounded aggregates. The bond strength is slightly higher than rounded aggregates but not as required for high strength concrete .
(iii) Angular Aggregates:
The angular aggregates consist well defined edges formed at the intersection of roughly planar surfaces and these are obtained by crushing the rocks. Angular aggregates result maximum percentage of voids (38-45%) hence gives less workability. They give 10-20% more compressive strength due to development of stronger aggregate-mortar bond. So, these are useful in high strength concrete manufacturing.
(iv) Flaky Aggregates:
When the aggregate thickness is small when compared with width and length of that aggregate it is said to be flaky aggregate, or on the other, when the least dimension of aggregate is less than the 60% of its mean dimension then it is said to be flaky aggregate.
(v) Elongated Aggregates:
When the length of aggregate is larger than the other two dimensions then it is called elongated aggregate or the length of aggregate is greater than 180% of its mean dimension.
(vi) Flaky and Elongated Aggregates:
When the aggregate length is larger than its width and width is larger than its thickness then it is said to be flaky and elongated aggregates. The above 3 types of aggregates are not suitable for concrete mixing. These are generally obtained from the poorly crushed rocks.
When the aggregate length is larger than its width and width is larger than its thickness then it is said to be flaky and elongated aggregates. The above 3 types of aggregates are not suitable for concrete mixing. These are generally obtained from the poorly crushed rocks.
Date : 16/07/2024
Time : 02 : 25 PM
When the length of aggregate is larger than the other two dimensions then it is called elongated aggregate or the length of aggregate is greater than 180% of its mean dimension.
Time : 04:11 PM
Date :12/07/2024
When the aggregate thickness is small when compared with width and length of that aggregate it is said to be flaky aggregate, or on the other, when the least dimension of aggregate is less than the 60% of its mean dimension then it is said to be flaky aggregate.
Flaky aggregates have more surface area and thus require more cement paste, thereby making concrete uneconomical. On the other hand, rounded aggregates have lesser surface area and hence require less lubricating paste as compared to flaky ones .
Date : 12/07/2024
Time : 02:28 PM
The angular aggregates consist well defined edges formed at the intersection of roughl planar surfaces and these are obtained by crushing the rocks. Angular aggregates result maximum percentage of voids (38-45%) hence gives less workability. They give 10-20% more compressive strength due to development of stronger aggregate-mortar bond. So, these are useful in high strength concrete manufacturing.
Date : 12/07/2024
Time : 11:01 AM
Shaped by attrition , But are not fully rounded .
The irregular or partly rounded aggregates are partly shaped by attrition and these are available in the form of pit sands and gravel. Irregular aggregates may result 35- 37% of voids. These will give lesser workability when compared to rounded aggregates. The bond strength is slightly higher than rounded aggregates but not as required for high strength concrete.
Date : 11/07/2024
Time : 03:30 PM
The rounded aggregates are completely shaped by attrition (the resistance of a granularmaterial to wear) and available in the form of seashore gravel. Rounded aggregates result in the minimum percentage of voids (32 – 33%) hence gives more workability. They require alesser amount of water-cement ratio. They are not considered for high-strength concrete because of poor interlocking behavior and weak bond strength .
Classification, Physical and mechanical properties, soundness, alkali-aggregate reaction, thermal properties of aggregate
Aggregates are the important constituents of the concrete which give body to the concrete andalso reduce shrinkage. Aggregates occupy 70 to 80 % of total volume of concrete. So, we can say that one should know definitely about the aggregates in depth to study more about concrete.
Classification of Aggregates as per Shape and Size: Aggregates are classified based on so many considerations, but here we are going to discuss about their shape and size classifications in detail.
Classification of Aggregates Based on Shape:
We know that aggregate is derived from naturally occurring rocks by blasting or crushing etc.,so, it is difficult to attain required shape of aggregate. But, the shape of aggregate will affect the workability of concrete. So, we should take care about the shape of aggregate. This care is not only applicable to parent rock but also to the crushing machine used. Aggregates are classified according to shape into the following types
Aggregates are classified according to shape into the following types Rounded aggregates
Irregular or partly rounded aggregates
Angular aggregates
Flaky aggregates
Elongated aggregates
Flaky and elongated aggregates
Time : 12 :08 AM
Date : 10/01/2024
ANY NATURAL SAND PARTICLES WON FROM THE LAND THROUGH THE MINING PROCESS When the aggregate is sieved through a 4.75mm sieve, the aggregate ...
