The 1963 edition of IS 2386 Part 1 outlines standardized procedures for evaluating the particle size distribution and shape characteristics of aggregates used in concrete. It details sieve analysis methods, determination of fine particles, and measurement of shape parameters like flakiness and elongation indices. This code is vital for engineers and material testers to verify that aggregates conform to prescribed quality standards for concrete applications in India.
Overview
The 1963 edition of IS 2386 Part 1 outlines standardized procedures for evaluating the particle size distribution and shape characteristics of aggregates used in concrete. It details sieve analysis methods, determination of fine particles, and measurement of shape parameters like flakiness and elongation indices. This code is vital for engineers and material testers to verify that aggregates conform to prescribed quality standards for concrete applications in India.
Audience
Contents
Structure
This section defines the extent of testing procedures for aggregates used in concrete, emphasizing particle size and shape analysis.
Key specifications include IS sieve sizes (both perforated plate and wire mesh types), thickness and length gauge dimensions, rounding rules per IS 2-1960, and balance accuracy requirements. A schematic diagram illustrates the aggregate testing workflow from sample preparation through sieve analysis and result plotting.
Lists the key IS sieve sizes for testing, thickness and length gauge dimensions for various aggregate sizes, and rounding off procedures to maintain consistency. Provides tables with sieve sizes and gauge dimensions based on aggregate size ranges.
Clarifies terms related to aggregate sizing and gauge measurements, specifies sieve sizes used for testing, and outlines reporting requirements according to the standard.
Describes the equipment needed such as metal cylinders (approx. 3 liters capacity), tamping rods with specified dimensions, balances with required accuracy, and scoops for sample handling. Visual diagrams summarize apparatus specifications.
Specifies minimum sample weights depending on maximum particle size, methods for reducing sample size (quartering or sample dividing), equipment accuracy, sieving arrangements, drying conditions, and general best practices to ensure representative and consistent samples.
Provides instructions for using thickness and length gauges, balance accuracy criteria, sieve specifications, sample drying and agitation requirements, and rounding off results. Includes flowcharts demonstrating the process from sample collection to reporting.
Explains the procedure for quantifying particles smaller than 75 microns by washing samples through a 75-micron sieve, drying the retained material, weighing, and calculating the percentage using a specified formula. Equipment specifications and graphical recording methods are also described.
Details sieve sizes used, minimum sample weights required for different maximum aggregate sizes, maximum allowable weight retained on sieves, thickness gauge calculation formula, and weighted percentage computations. Visual aids depict sieve hierarchy.
Describes how to calculate flakiness and elongation indices by measuring particle dimensions against thickness and length gauges, including formulae for weighted percentages. Notes amendments to shape factor values and explains the significance of shape characterization in concrete aggregate quality.
Outlines requirements for clear calculation and presentation of results in line with IS 2-1960 rounding rules, emphasizing matching significant figures to standard specifications. Includes examples and a flowchart illustrating the reporting workflow.
Highlights balance accuracy requirements, metal gauge conformity, usage of IS standard sieves, and rounding off protocols to guarantee reliable and reproducible measurement results.
Compiles key dimensional tables for thickness and length gauges, sieve specifications, material finer than 75 microns testing instructions, and rounding off guidelines. Provides summary diagrams for thickness gauge calculations.
Frequently Asked
The sieve analysis procedure involves: 1) Selecting a minimum sample weight based on the maximum aggregate size as per the standard's table; 2) Reducing the sample using quartering or a sample divider; 3) Drying the sample to air-dry condition; 4) Using IS standard sieves ranging from 80 mm to 75 microns; 5) Sieving the sample manually or mechanically ensuring no overloading of finer sieves; 6) Weighing the material retained on each sieve while adhering to maximum weight limits; 7) Calculating percentages retained and passing on each sieve; and 8) For all-in aggregates, computing weighted percentages if separation into coarse and fine fractions is performed.
According to IS 2386 Part 1, the fines content is determined by first weighing the dry aggregate sample, then washing it through a 75-micron sieve, drying the retained material, and weighing it again. The percentage finer than 75 microns is calculated using the formula: ((Original dry weight - Weight after washing) / Original dry weight) × 100. This method ensures removal of clay and soluble fines, providing an accurate measure of fine particles.
The standard requires: 1) Square hole perforated plate sieves with sizes ranging from 80 mm down to 4.75 mm; 2) Fine mesh wire cloth sieves sized from 3.35 mm down to 75 microns; all conforming to IS 460-1962; 3) Metal cylinders approximately 3 liters in capacity; 4) Tamping rods of circular cross-section with specified dimensions; 5) Balances capable of measuring up to 10 kg with 1 gram readability; and 6) Scoops sized for handling about 1 liter of sample. These ensure uniformity and accuracy in testing.
Flakiness index is determined by calculating the percentage by weight of particles whose least dimension (thickness) is less than 0.6 times their mean dimension, using thickness gauges for each sieve fraction. Elongation index is the percentage by weight of particles whose greatest dimension (length) exceeds 1.8 times their mean dimension. Both tests apply to aggregate sizes 6.3 mm and above. Weighted percentages are computed across sieve fractions to quantify shape characteristics influencing concrete quality.
Samples must be dried at a temperature between 100°C and 110°C (±5°C) for a minimum of 24 hours in shallow trays within a well-ventilated oven until constant weight is achieved. Weighing should be accurate to within 0.1%. Before sieving, samples should be brought to an air-dry state either by cooling or controlled drying. Post-drying, samples are weighed, sieved starting from the largest sieve, and then placed in water-filled containers for agitation as part of the testing process. This ensures moisture consistency and reliable test results.
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