How the size of aggregate affects the workability of concrete?
Surface area of aggregates depends on the size of aggregates. For a unit volume of aggregates with large size, the surface area is less compared to same volume of aggregates with small sizes. Hence, lower sizes of aggregates with same water content are less workable than the large size aggregates.
How would the maximum aggregate size affect concrete mix design?
Maximum Aggregate Size As the maximum size of coarse aggregate reduces, surface area of coarse aggregate increases. Higher the surface area, greater is the water demand to coat the particles and generate workability.
What is the maximum size of aggregate used for concrete?
The optimum compressive strength of concrete is reached by using aggregates of 9.5mm maximum size.
What is the effect of maximum size aggregate on strength?
A. 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 maximum and minimum size of aggregate for a workable concrete?
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.
Why is the nominal maximum aggregate size important?
Maximum aggregate size can affect HMA and base/subbase courses in several ways. In HMA, instability may result from excessively small maximum sizes; and poor workability and/or segregation may result from excessively large maximum sizes (Roberts et al. 1996).
What is the maximum aggregate size?
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”.
What does nominal maximum aggregate size mean?
Nominal maximum size. The largest sieve that retains some of the aggregate particles but generally not more than 10 percent by weight. Superpave defines nominal maximum aggregate size as “one sieve size larger than the first sieve to retain more than 10 percent of the material” (Roberts et al., 1996).
What is the effect of maximum size of aggregate on concrete strength?
The effect of maximum size of aggregate on concrete strength. 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. But in the high-strength range, over 40 MPa (5800 psi),…
How does the water content of concrete affect its workability?
The higher the water content per cubic meter of concrete, the higher will be the fluidity of concrete, which affect the workability. Water requirement is mainly associated with absorption by aggregates surface& filling up the voids between aggregates.
What is the effect of variation in the size of aggregates?
Variation in the size of Aggregates changes the water demand, cement content, micro-cracking (strength) in concrete. It also effects pumpability, and durability of concrete. When the particles are of uniform size the spacing is the greatest, but when a range of sizes is used the void spaces are filled and the paste requirement is lowered.
What are the disadvantages of adding extra water to concrete?
Water requirement is mainly associated with absorption by aggregates surface& filling up the voids between aggregates. However, Adding Extra Water to the Concrete Mix can be Disadvantageous, as Given Below: The strength of the concrete may get reduced.