When the size of aggregate is greater than 4.75 mm ( say 5 mm) it is called coarse aggregate. Graded aggregates are used for better particle packing. The larger the size of aggregate lesser the cement required for same strength up to certain grade of concrete. The constraints for Nominal Maximum Size of Aggregate (NMSA) are follows
Because maximum aggregate size can impact concrete properties such as shrinkage, and also the cost of concrete, the largest aggregate size consistent with the requirements of 26.4.2.1 should be permitted. With the w/cm fixed, the larger the nominal maximum size of aggregates, the lower the cement content for a given consistency.
Typically the aggregate is in three separate stockpiles and combined during the mixing process. There is two stock piles for coarse aggregate, one with a maximum particle size of 1 1/4”, the other pile with a maximum particle size of 3/4” and one stockpile for fines 100% passing a #4 sieve (sand). What are the grades of coarse aggregate?
There is two stock piles for coarse aggregate, one with a maximum particle size of 1 1/4”, the other pile with a maximum particle size of 3/4” and one stockpile for fines 100% passing a #4 sieve (sand). What are the grades of coarse aggregate? “Gradation”. The sieve analysis is conducted to determine this particle size distribution.
R608. 5.1. 3 Maximum Aggregate Size The nominal maximum size of coarse aggregate shall not exceed one-fifth the narrowest distance between sides of forms, or three-fourths the clear spacing between reinforcing bars or between a bar and the side of the form.
Conditions That Decide Maximum Size of Coarse Aggregate to be Used in Concrete. It should not be more than one fourth of the minimum thickness of the member provided that the concrete can be placed without difficulty so as to aurround all reinforcement thoroughly and fill the corner of the form.
20 mmThe slump at the point of delivery should be 20–120 mm and the maximum size of coarse aggregate should be 10, 14 or 20 mm.
Effect of coarse aggregate sizes in concrete : As the sizes of coarse aggregate increases then the compressive strength will also increase with constant water to cement ratio(w:c -0.5 and Mix proportion 1:2:4) The workability of concrete get improved after increasing larger sizes of aggregates in concrete.
In the majority of concrete works, aggregate sizes of 20 mm or smaller are used. To ensure good coarse aggregate compaction and higher concrete density, it is recommended to mix 20 mm and 10 mm coarse aggregates in the ratio of 70:30 or 60:40.
Coarse aggregates are any particles greater than 0.19 inch, but generally range between 3/8 and 1.5 inches in diameter.
When the aggregate is sieved through 4.75 mm size the aggregate is retained is known as coarse aggregate. Larger than 4.75mm size is coarse sand or aggregate, so coarse aggregate size arranging between 5mm to 256 mm or more.
The size of your coarse aggregates is your main factor in determining the strength of your concrete. Generally, you'll want smaller coarse aggregates for stronger concrete, with 20mm aggregates fulfilling the threshold for strong concrete, and 40mm aggregates the threshold for normal strength concrete.
The most popular field test to measure the quality of aggregate is the sieve test. It is not possible to measure shape characteristic and other parameters by sieve analysis. Therefore, it is essential to develop rapid assessment techniques for quality control of aggregate.
Rough textured and angular coarse aggregate provide greater mechanical bond and are generally more suitable for use in high strength concrete than smooth textured aggregates.
The usual range employed is between 9.5mm and 37.5mm in diameter. - Fine aggregates are usually sand or crushed stone that are less than 9.55mm in diameter. Typically the most common size of aggregate used in construction is 20mm. A larger size, 40mm, is more common in mass concrete.
Overall, concrete with the larger aggregates exhibited greater compressive strength than that of concrete with smaller aggregates. This is due to large aggregates being able to interlock within the mixture, providing strength based on its and the cement internal properties.
ASTM C 125 defines the maximum aggregate size in one of two ways: Maximum size. The smallest sieve through which 100 percent of the aggregate sample particles pass. Superpave defines the maximum aggregate size as “one sieve larger than the nominal maximum size” (Roberts et al., 1996).
Aggregate Size Nominal Maximum Size: The smallest sieve opening through which the entire amount of aggregate is permitted to pass. coarse aggregate MUST pass the 1.5” sieve but 95 - 100% MAY pass the 1” sieve, therefore # 57 aggregate is considered to have a Maximum size of 1.5” and an Nominal Maximum size of 1”.
The maximum nominal size of aggregate is determined by the sieve analysis and is designated by the sieve higher than the largest size on which 15% or more of the aggregate is retained. The maximum nominal size of aggregate to be used in concrete depends by the size of section and the spacing of reinforcement.
Generally the 9.5-37.5 mm diameter range aggregate are used in RCC concrete work. But Maximum size of aggregate generally on site used are 40 mm. For ease of compaction and workability sometimes on site 10-15 mm aggregate are used.
More specifically, a #57 aggregate is the combination of #5 and #7 aggregates ranging from 1 to 0.19 inch.
The term “aggregates” as used in the construction industry is a broad category of coarse and fine particulate material including sand, gravel, crushed stone, slag, recycled concrete, and geosynthetic aggregates and are actually the most mined materials in the world.
Coarse aggregate can be described as uncrushed, crushed, or partially crushed gravel or stone. This type of aggregate is described as how it is graded. For example, ¾” nominal size graded aggregate means that most of the aggregate passes a 3/4” sieve.
Aggregates can be categorized into three groups: fine aggregate, coarse aggregate, or all-in aggregate . Fine aggregate , such as concrete or masonry sand is defined as material that mostly passes through a 4.75 mm IS sieve.
All-in aggregate, similar to that of its name, is aggregate containing a proportion of material of all sizes from a pit, crushing plant or river bed. Also known as Ballast, this type of material is generally used to repair small cracks and pavement foundations.
Chaney Enterprises’ aggregate materials meet the ASTM C 33 Standard and can be found at our various locations throughout Maryland, Virginia, and Delaware.
When the size of aggregate is greater than 4.75 mm ( say 5 mm) it is called coarse aggregate. Graded aggregates are used for better particle packing. The larger the size of aggregate lesser the cement required for same strength up to certain grade of concrete. The constraints for Nominal Maximum Size of Aggregate (NMSA) are follows
Only 10mm size of aggregate is used in case of Self- Compacting concrete.
Even IRC 112:2011, the minimum permissible cement can be adjusted by - 30 kg when we move from 20 mm NMSA to 40 mm NMSA.
In general 20 mm is used as NMSA but use of 40 mm provides economy for substructures. For too congested structures 12.5 mm or 10 mm is also used. For PQC 31.5 mm and DLC 26.5 mm is considered. For mass concrete dams up to 150 mm is used. For shotcretes 8 mm is used.
In general 20 mm is used as NMSA but use of 40 mm provides economy for substructures. For too congested structures 12.5 mm or 10 mm is also used. For PQC 31.5 mm and DLC 2
For basement PCC and footing PCC-40mm aggregate is used (1.5 jalli in tamil)
It varies…But in general for PCC its 40 mm down nominal size and for standard RCC work its a mix of 20 mm down and 10 mm down aggregates.