IS 8047:1989 is the Indian Standard (BIS) for low heat portland cement - specification. This standard specifies the requirements for the manufacture, chemical composition, and physical properties of Low Heat Portland Cement. It is intended for use in mass concrete structures where controlling the heat of hydration is critical to prevent thermal cracking, such as in dams and large foundations. The code sets limits for heat generation, strength development, setting times, and soundness.
Specifies requirements for low heat portland cement, suitable for mass concrete structures to minimize thermal cracking.
Key reference values — verify against the current code edition / project specification.
| Reference | Value | Clause |
|---|---|---|
| Defining property | Capped heat of hydration (7-day & 28-day limits) | Critical |
| Chemistry | Lower C₃A/C₃S, higher C₂S (slow phase) | Concept |
| Early strength | Low by design; accept at later age | Caution |
| Heat measured by | IS 4031 Part 10 / IS 11262 calorimeter | Cross-ref |
| Use for | Mass concrete, thick rafts/blocks, dams | Application |
| Pair with | IS 457 controls (lift/pre-cool/cooling pipes) | Cross-ref |
| Sibling spec | IS 12600 (low-heat Portland cement) | Cross-ref |
| Verify | Heat limit by test — not the label | Caution |
IS 8047:1989 is a specification for low-heat Portland cement — OPC formulated for a low heat of hydration, used in mass concrete (dams, thick rafts, large foundation blocks) to control thermal cracking. It is closely related to IS 12600 (the other low-heat Portland cement specification) and is the cement-side partner of the IS 457 mass-concrete construction code.
It sits in the cement / mass-concrete stack:
Like all low-heat Portland cements, IS 8047 cement limits the high-heat clinker phases (lower C₃A/C₃S, higher C₂S) to cap the heat of hydration, with the inherent consequence:
The engineering point is identical to IS 12600: low-heat cement trades early strength for low heat on purpose, which is exactly right for mass concrete (where heat, not early strength, governs) and wrong for fast-cycle structural work. It is a *system* component — it reduces heat but does not replace the IS 457 construction controls (lean mix, limited lift height, pre-cooling, cooling pipes, placing-temperature limit). For practical purposes engineers should treat IS 8047 and IS 12600 as the low-heat Portland cement option and specify the current/appropriate one with verified heat figures.
Scenario: a thick foundation block / dam-type mass pour where thermal cracking governs.
Step 1 — cement choice: low-heat Portland cement (IS 8047 / IS 12600) or PPC — confirm the heat-of-hydration limit by test (IS 11262/IS 4031).
Step 2 — minimise heat further: lowest cement content for the (modest) required strength, large well-graded aggregate per IS 457.
Step 3 — construction controls: limited lift height, pre-cooling / placing-temperature limit, embedded cooling pipes for large blocks, contraction joints.
Step 4 — accept on later strength: judge strength at the specified later age, allow extended formwork/loading times.
Step 5 — cure long & avoid rapid surface cooling.
Cement choice + lean mix + IS 457 controls together cap the peak temperature and ΔT — that, not the cube, protects the massive structure.
1. Using it in fast-cycle structural work. Slow early strength stalls formwork cycles — low-heat cement is for mass concrete.
2. Judging it on OPC early-strength timelines. 7-day strength is low by design; accept at the specified later age.
3. Relying on the cement alone for mass concrete. It reduces heat but does not replace the IS 457 lift/pre-cooling/cooling-pipe controls.
4. Not verifying the heat limit. The defining property is heat of hydration — confirm by IS 11262/IS 4031 test, not the label.
5. Over-cementing to recover early strength. Re-introduces the heat the cement was chosen to avoid.
IS 8047 is reaffirmed and, with IS 12600, defines the low-heat Portland cement option — and the practitioner takeaway is the same conceptual one: cement selection for mass concrete is a deliberate trade of early strength for low heat, the correct trade where heat-of-hydration cracking governs and the wrong one for fast structural cycles. Two disciplines matter: confirm the heat limit by measurement (IS 11262/IS 4031), not by the bag label; and remember the cement is only the chemistry half of a system completed by the IS 457 construction controls. In modern practice PPC/slag is often used to obtain a low-heat effect, with a specified low-heat Portland cement where the heat limit must be guaranteed. Choose it for the heat problem, accept it on late strength, and pair it with mass-concrete construction discipline.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Heat of Hydration (7 days) | ≤ 65 cal/g (≈ 272 J/g) | ≤ 250 J/g | ASTM C150 (Type IV) |
| Heat of Hydration (28 days) | ≤ 75 cal/g (≈ 314 J/g) | ≤ 290 J/g (Optional) | ASTM C150 (Type IV) |
| Compressive Strength (7 days) | ≥ 16 MPa | ≥ 8.0 MPa | ASTM C150 (Type IV) |
| Compressive Strength (28 days) | ≥ 35 MPa | ≥ 17.0 MPa | ASTM C150 (Type IV) |
| Fineness (Blaine Air Permeability) | ≥ 320 m²/kg | ≥ 260 m²/kg | ASTM C150 (Type IV) |
| Initial Setting Time (Vicat) | ≥ 60 minutes | ≥ 45 minutes | ASTM C150 (Type IV) |
| Final Setting Time (Vicat) | ≤ 600 minutes | ≤ 420 minutes | ASTM C150 (Type IV) |
| Tricalcium Aluminate (C3A) % by Bogue | ≤ 5% | ≤ 7% (Optional) | ASTM C150 (Type IV) |