Table of Contents
- 1 What is the effect of size of aggregate on concrete?
- 2 What are the effects of aggregate size on the compressive strength of concrete?
- 3 Why aggregate proportioning is important?
- 4 Why is grading of aggregates important?
- 5 What is the meaning of 20mm down aggregate?
- 6 What is the size of NMSA in concrete?
What is the effect of size of aggregate on concrete?
As the nominal maximum size of the aggregate is increased, the amount of water needed for the same workability is reduced. At the same cementitious material content, strength is therefore greater because the w/cm is lower.
What is the purpose of small aggregate in concrete?
Key points Aggregates make up some 60 -80\% of the concrete mix. They provide compressive strength and bulk to concrete. Aggregates in any particular mix of concrete are selected for their durability, strength, workability and ability to receive finishes.
What are the effects of aggregate size on the compressive strength of concrete?
strengths than the larger sized coarse aggregate. Cook observed that the difference in compressive strengths due to aggregate size is increasingly larger with a decreasing water-to-cement ratio and increasing test age. The smaller sized coarse aggregate also increases the flexural strength of the concrete.
How does aggregate size affect slump?
A.: If the quantities of coarse aggregate, fine aggregate, cement and water are the same for both mixes, the mix with l l/2-inch aggregate will have greater slump and will probably bleed more. If both mixes are plastic the resulting strengths of the two mixes will probably be about the same.
Why aggregate proportioning is important?
The aggregate suspension method of mixture proportioning (ACI 211.6) provides a way to satisfy everyone. This method allows the engineer to fine-tune the proportions of the various aggregate size fractions to optimize the particle-size grading for high performance concrete.
How does aggregate size affect water demand and cement content?
Higher the surface area, greater is the water demand to coat the particles and generate workability. Smaller maximum size of coarse aggregate would require greater fine aggregate content to coat particles and maintain cohesiveness of concrete mix.
Why is grading of aggregates important?
The grading or size distribution of aggregate is an important characteristic because it determines the paste requirement for workable concrete. The more these voids are filled, the less workable the concrete becomes, therefore, a compromise between workability and economy is necessary.
Why grading of aggregate is important in concrete?
What is the meaning of 20mm down aggregate?
20mm down aggregate/ coarse aggregate means most of the particle will pass through 20mm sieve and the particles of smaller size will retain in 4.75mm sieve. The stone dust particle (less than 150 micron) are generally not recommended since it affects workability of concrete (Subsequently quantity of cement has to be increased)
What is the maximum size of aggregate in a concrete slab?
Size of aggregate should not greater than 1/16 of least dimension of member,then only aggregate will be filled in all corners. Usually 20 mm aggregate is preferred. For reducing voids we have to use combination of 20 mm and 10 mm aggregate.
What is the size of NMSA in concrete?
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.
What is the difference between 10mm and 20mm coarse aggregate?
When you use a smaller aggregate, such as the 10mm as your nominal coarse aggregate size, the specific surface area of the total volume of coarse aggregate is much higher than for the 20mm aggregate.