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IS 16715:2018 is the Indian Standard (BIS) for ground granulated blastfurnace slag for use in cement, mortar and concrete - specification. This standard specifies the requirements for Ground Granulated Blast-furnace Slag (GGBS), a pozzolanic material used as a partial replacement for cement. It covers essential chemical and physical properties, such as glass content, fineness, and strength activity index, to ensure its suitability for use in cement, mortar, and concrete.
Specifies requirements for ground granulated blastfurnace slag (GGBS) for use as an active mineral admixture or cement replacement in cement, mortar, and concrete.
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! Using GGBS generally slows down the setting time and early strength gain of concrete, but significantly improves long-term strength and durability, especially against sulphate and chloride attacks.
! The replacement percentage of cement with GGBS typically ranges from 30% to 70%, depending on the application and desired properties. Higher replacement levels are common in mass concrete to control heat of hydration.
! Always obtain a manufacturer's test certificate for each batch of GGBS, paying close attention to glass content and activity index, which are critical indicators of its reactivity.
ground granulated blastfurnace slagGGBScementconcretemortarsupplementary cementitious material
International Equivalents
Similar International Standards
ASTM C989 / C989M - 18ASTM International, USA
HighCurrent
Standard Specification for Slag Cement for Use in Concrete and Mortars
Specifies GGBS (termed 'slag cement') for use as a cementitious material in concrete and mortar.
EN 15167-1:2006CEN (European Committee for Standardization), Europe
HighCurrent
Ground granulated blast furnace slag for use in concrete, mortar and grout - Part 1: Definitions, specifications and conformity criteria
Provides specifications and conformity criteria for GGBS for use in concrete, mortar, and grout.
BS EN 15167-1:2006BSI (British Standards Institution), UK
HighCurrent
Ground granulated blast furnace slag for use in concrete, mortar and grout - Part 1: Definitions, specifications and conformity criteria
The UK's adoption of the European standard, covering the same scope for GGBS.
AS 3582.2:2016Standards Australia, Australia
HighCurrent
Supplementary cementitious materials, Part 2: Slag - Ground granulated iron blast-furnace
Specifies requirements for ground granulated iron blast-furnace slag for use as a cementitious material.
Key Differences
≠IS 16715 does not categorize GGBS into grades. In contrast, ASTM C989 classifies slag cement into three grades (Grade 80, 100, and 120) based on their slag activity index, which indicates different levels of reactivity.
≠IS 16715 mandates a minimum glass content of 90%, which is significantly higher than the requirement in EN 15167-1, which specifies a minimum of two-thirds (≈67%) glass content.
≠The Indian standard specifies a limit for Manganese Oxide (MnO) content at a maximum of 5.5%. Most other international standards, including ASTM C989 and EN 15167-1, do not specify a limit for MnO.
≠The minimum fineness requirement in IS 16715 is 320 m²/kg. This differs from EN 15167-1, which requires a lower minimum of 275 m²/kg, and ASTM C989, which does not specify a mandatory minimum value, leaving it to be agreed upon.
Key Similarities
≈All standards define GGBS as a glassy, granular material formed by rapid quenching of molten blast furnace slag, a by-product from iron manufacturing.
≈IS 16715, ASTM C989, and EN 15167-1 all use the Slag Activity Index (SAI) as a primary performance indicator. This test measures the compressive strength of a mortar made with GGBS compared to a reference Portland cement mortar.
≈All standards specify the use of the Blaine air permeability method (or an equivalent) for determining the fineness of the ground slag, recognizing its critical impact on reactivity.
≈There is a broad agreement on the control of certain chemical components that affect durability and performance, such as Sulphate (SO₃) and Loss on Ignition (LOI), with very similar or identical limit values across standards.
Parameter Comparison
Parameter
IS Value
International
Source
Fineness (Blaine)
≥ 320 m²/kg
≥ 275 m²/kg
EN 15167-1:2006
Glass Content
≥ 90%
≥ 67% (two-thirds)
EN 15167-1:2006
Slag Activity Index (7 days)
≥ 65%
≥ 75% (for Grade 100)
ASTM C989 / C989M - 18
Slag Activity Index (28 days)
≥ 90%
≥ 70%
EN 15167-1:2006
Manganese Oxide (MnO)
≤ 5.5%
Not Specified
ASTM C989 / C989M - 18
Sulphate content (as SO₃)
≤ 4.0%
≤ 4.0%
ASTM C989 / C989M - 18
Magnesium Oxide (MgO)
≤ 17.0%
Not Specified (Optional expansion test required if MgO is high)
ASTM C989 / C989M - 18
⚠ Verify details from original standards before use
Key Values6
Quick Reference Values
Minimum Glass Content85%
Maximum Magnesium Oxide (MgO) Content17.0%
Maximum Sulphide Sulphur (S) Content2.0%
Maximum Chloride Content0.1%
Minimum Fineness (Specific Surface)320 m²/kg
Minimum 7-day Slag Activity Index75%
Tables & Referenced Sections
Key Tables
Table 1 - Chemical Requirements for Ground Granulated Blastfurnace Slag
Table 2 - Physical Requirements for Ground Granulated Blastfurnace Slag
What is the minimum fineness required for GGBS by IS 16715?+
A minimum specific surface area of 320 m²/kg is required (Table 2).
What is the maximum permissible chloride content in GGBS?+
The maximum chloride content is 0.1 percent by mass (Table 1).
What is the Slag Activity Index?+
It is a measure of the reactivity of GGBS, determined by comparing the compressive strength of a mortar made with a GGBS-cement blend to a reference mortar made with only cement (Clause 4.2.3).
Why is 'glass content' important for GGBS?+
A high glass content (amorphous state) is essential for the pozzolanic reactivity of GGBS. The minimum required is 85% (Table 1).