What is coarseness factor?

Coarseness Factor was derived from the aggregate gradation to predict the workability of the concrete mix (Shilstone, 1990). Coarseness Factor is the proportion of plus 3/8″ coarse particles in relation to the total coarse particles, expressed as a percent.

How do you calculate coarseness?

Coarseness and Workability (Shilstone) Chart The coarseness and workability factors shall be calculated and plotted in a coarseness and workability (Shilstone) chart as shown in the figure above: Coarseness Factor = Combined Percent Passing 3/8 in. (9.5 mm) Sieve Combined Percent Passing No.

How do you calculate workability factor?

The workability factor is the cumulative combined percent passing the No. 8 sieve. Increase the workability factor by 2.5 percentage points for every 94 lb. per cubic yard of cementitious material used in excess of 564 lb.

What is workability and factors affecting workability?

Factors affecting the workability of concrete are materials such as water content, cement concrete, sand and aggregate properties such as size, shape, grading, mix design ratio and use of admixtures. Each and every process and materials involved in concrete mixing affects the workability of concrete.

What is a tarantula curve?

The Tarantula Curve method is a tool used to analyse and optimize aggregate gradings in concrete. This method was developed in the US specifically for use with concrete pavements.

What is combined gradation?

When the aggregate gradations for a PCC mixture are sampled and tested individually, the results must be mathematically combined to create a theoretical combined gradation. This combined gradation is based on their relative percent volume in the mixture.

What is the importance of aggregate sieve test?

The sieve analysis determines the gradation (the distribution of aggregate particles, by size, within a given sample) in order to determine compliance with design, production control requirements, and verification specifications.

What is fineness modulus used for?

The significance of fineness modulus (FM) is in specifying the proportions of fine and coarse aggregates when designing concrete mixes. The higher the value of FM, the coarser the aggregate. Generally, a lower FM results in more paste, making the concrete easier to finish.

What is meant by Workability?

Definition of workable 1 : capable of being worked a workable material. 2 : practicable, feasible a workable system.

What are the different factors affecting workability?

Factors Affecting Workability of Concrete

• Water Content : The amount of water content available in a volume of concrete will have a significant effect on the workability of concrete.
• Mix Proportions :
• Size of Aggregates :
• Shape of Aggregates :
• Surface Texture of Aggregates :
• Grading of Aggregates :
• Use of Admixtures :

How do you calculate combined gradation?

Determine the theoretical combined gradation from the individual gradations. This is done by multiplying the percent retained on each sieve for the individual gradations by the relative portion of the aggregate volumes. Then total the percent retained of each product for each sieve size.

What is combined grading of aggregate?

A. Combined fine and coarse aggregates grading is specified to ensure that a satisfactory amount of aggregate with a minimum amount of void spaces is obtained. This will enable the use of a minimum amount of paste (water and cementitious material) in concrete, improving the dimensional stability and the durability.

What is the advantage of sieve?

Advantages of the sieve analysis include easy handling, low investment costs, precise and reproducible results in a comparably short time and the possibility to separate the particle size fractions. Therefore, this method is an accepted alternative to analysis methods using laser light or image processing.

How fineness modulus is correlated to workability?

It also paints an accurate picture of the concrete’s workability, which is measured in terms of slump value. Generally speaking, the higher the fineness modulus, the higher the slump value — or in other words — the stiffer the concrete will be.

What is flakiness and elongation?

Flakiness Index is the percentage by weight of particles in it, whose least dimension (i.e. thickness) is less than three-fifths of its mean dimension. Elongation Index is the percentage by weight of particles in it, whose largest dimension (i.e. length) is greater than one and four-fifths times its mean dimension.

What is an example of workability?

Definition of ‘workability’ The workability of a substance, especially a metal, is how easily it can be changed into a new shape. The workability of a metal can usually be improved by increasing its temperature.

What is workability of a concrete?

Workability of Concrete is a broad and subjective term describing how easily freshly mixed concrete can be mixed, placed, consolidated, and finished with minimal loss of homogeneity.

What increases the workability of concrete?

Explanation: Workability of concrete can be improved by more cement and water with proper water cement ratio. Explanation: Workability should be obtained by the use of a well-graded aggregate which has the largest maximum particle size possible.