IS 2541:1991 is the Indian Standard (BIS) for preparation and use of lime concrete. This standard outlines the code of practice for the preparation, laying, and curing of lime concrete in building construction. It provides essential guidelines on material selection, proportioning, and mixing techniques, primarily for use in foundation bases, under-floors, and roof terracing.
Code of practice for preparation and use of lime concrete
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Lime Classification | Class A (Eminently hydraulic), Class B (Semi-hydraulic), Class C (Fat lime) | Natural Hydraulic Lime (NHL 2, 3.5, 5), Formulated Lime (FL), Calcium Lime (CL 70, 80, 90) | BS EN 459-1 |
| Primary Pozzolana Type | Surkhi (burnt clay powder) and Cinders | Fly Ash, Raw or Calcined Natural Pozzolan | ASTM C593 |
| Minimum Curing Period (Moist) | At least 10 days for lime-surkhi concrete; 7 days for lime-cinder concrete | Generally longer, context-dependent; guidance often suggests protecting and dampening for several weeks. | Historic England Technical Guidance |
| Maximum Coarse Aggregate Size | Generally 40 mm for mass concrete | Specified by nominal size fractions (D/d), e.g., 20/40 mm. Dmax depends on application and element size. | BS EN 12620 |
| Slaking of Quicklime | Specifies methods for pit slaking and platform slaking. | Modern practice predominantly uses industrially produced pre-slaked hydrated lime or NHL powders, avoiding on-site slaking. | General practice based on BS EN 459-1 materials |
| Compressive Strength Test | Specifies 15 cm cubes tested at 28 days and 90 days. | For NHL mortars, typically 40x40x160mm prisms tested at 28 days. | BS EN 459-2 (Test Methods) |