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IS 7325:1974 is the Indian Standard (BIS) for apparatus for determining constituents of fresh concrete. This standard specifies the requirements for the apparatus used to determine the constituents of a fresh concrete mix. It covers two primary methods: the buoyancy method and the siphon-can method, detailing the dimensions, materials, and construction of the necessary equipment to ensure consistent and accurate testing.
Specification for apparatus for determining constituents of fresh concrete
Overview
Status
Current
Usage level
Specialized
Domain
Materials Science — Cement, Concrete, Aggregates and RCC
! This standard has been superseded and merged into IS 1199 (Part 3):2018. Always refer to the latest standard for current practices and compliance.
! The accuracy of the test results is highly dependent on the precise dimensions and calibration of the apparatus as specified in this code.
! These methods provide a physical means to verify the actual proportions of materials in a fresh concrete batch, serving as a crucial quality control check.
BS EN 12350-7:2019BSI / CEN (United Kingdom / European Committee for Standardization)
HighCurrent
Testing fresh concrete - Part 7: Air content - Pressure methods
Specifies the apparatus and method for determining air content using a pressure meter, which is one component covered by IS 7325.
ASTM C231 / C231M - 17aASTM International (USA)
HighCurrent
Standard Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method
Directly equivalent to the air content apparatus (pressure meter) portion of IS 7325, based on the same physical principle (Boyle's Law).
BS 1881: Part 2: 1970BSI (United Kingdom)
HighWithdrawn
Methods of testing fresh concrete
Historically specified a washout/buoyancy apparatus for fresh concrete analysis, which is the direct conceptual precursor to the main apparatus in IS 7325.
ISO 1920-2:2016ISO (International Organization for Standardization)
MediumCurrent
Testing of concrete - Part 2: Properties of fresh concrete
A normative standard that references methods like those in the EN 12350 series for testing fresh concrete properties, including air content.
Key Differences
≠IS 7325 combines apparatus for both constituent analysis (washout/buoyancy) and air content determination in one standard. Modern international standards like ASTM and EN have separate, dedicated standards for each test method.
≠The physical separation (washout) method for determining all concrete constituents, for which the main IS 7325 apparatus is designed, is largely considered obsolete and is not included in current major EN or ASTM standards due to concerns about accuracy and precision.
≠IS 7325 provides highly prescriptive dimensional drawings for the apparatus. In contrast, modern standards like ASTM C231 and EN 12350-7 are more performance-based, specifying volumes, pressure ranges, and calibration criteria, allowing for more variation in apparatus design.
≠IS 7325 is a 1974 specification and has not been revised, reflecting the technology of that era. Equivalent international standards are frequently updated to incorporate new research, improved calibration techniques, and material advancements.
Key Similarities
≈The principle for determining air content via the pressure meter ('Air Indicator' in IS 7325) is based on Boyle's Law, which is identical to the principle used in ASTM C231 (Type B Meter) and BS EN 12350-7.
≈The fundamental components of the pressure air meter, including a sealed measuring bowl, a cover assembly with an air chamber, a pressure gauge, and a pump, are functionally identical across IS 7325, ASTM C231, and EN 12350-7.
≈All standards mandate the use of a rigid, watertight measuring bowl made of a metal not easily corroded by cement paste.
≈The requirement for regular calibration of the apparatus, including verification of the pressure gauge and determination of the apparatus's intrinsic expansion factor, is a common and critical requirement in all related standards.
Parameter Comparison
Parameter
IS Value
International
Source
Minimum Capacity of Measuring Bowl (Air Meter)
0.005 m³ (5 litres)
≥ 5 litres
BS EN 12350-7:2019
Minimum Capacity of Measuring Bowl (Air Meter)
0.005 m³ (5 litres)
≥ 0.20 ft³ (approx. 5.7 litres)
ASTM C231 / C231M - 17a
Tamping Rod Diameter
16 mm (via reference to IS 10086)
16 mm ± 1 mm
BS EN 12350-1 (for 12350-7)
Tamping Rod Diameter
16 mm (via reference to IS 10086)
5/8 in. (16 mm)
ASTM C231 / C231M - 17a
Pressure Gauge Graduations
In divisions of 0.1 percent air
Smallest division shall be 0.1 % air content or less
BS EN 12350-7:2019
Material of Measuring Bowl
Cast aluminium alloy or other suitable metal
Steel, or other hard metal not readily attacked by cement paste
ASTM C231 / C231M - 17a
⚠ Verify details from original standards before use
Key Values6
Quick Reference Values
Buoyancy method container internal diameter350 ± 25 mm
Buoyancy method container internal height350 ± 25 mm
No, it has been superseded and merged into IS 1199 (Part 3):2018. The new standard should be used.
What are the two main types of apparatus specified in this code?+
The code specifies apparatus for the Buoyancy Method (Clause 2) and the Siphon-Can Method (Clause 3).
What is the purpose of the apparatus described in IS 7325?+
The apparatus is used to determine the actual quantities of cement, water, and aggregates in a sample of fresh concrete, also known as concrete analysis or cube testing.
What is the specified size of the container for the buoyancy method?+
The internal diameter and height should both be approximately 350 mm, with a tolerance of ±25 mm, as per Clause 2.1.