IS 13077:1991 is the Indian Standard (BIS) for guide for preparation and use of mud mortar in masonry. This standard serves as a guide for selecting suitable soils and preparing mud mortar for use in masonry. It outlines the process from material selection, preparation, and application to the protection of finished mud masonry walls, primarily for low-cost and rural construction.
Guide for preparation and use of mud mortar in masonry
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Recommended Mortar Joint Thickness | 15 to 20 mm | 10 to 15 mm | NZS 4298:2020 |
| Soil Composition (Clay Content) | 10 - 15% | 10 - 25% (for adobe mortar soil) | NZS 4298:2020 |
| Compressive Strength of Mortar | Not specified in the standard. | ≥ 0.4 N/mm² (for unstabilised earth mortar Class U I) | DIN 18947:2013 |
| Linear Shrinkage Limit | Qualitative guidance only; no quantitative limit. | ≤ 2.0% | NZS 4298:2020 |
| Use of Organic Binders (e.g., Dung) | Permitted (cow dung is mentioned as a binder). | Prohibited (organic content limited to <1-5% by mass, excluding specified fibres). | DIN 18947:2013 |
| Durability Requirement (Water) | No quantitative test specified. | Performance test required (e.g., max erosion depth of 2mm in a standard spray test). | NZS 4298:2020 |
| Stabilizer (Cement/Lime) | Mentioned as an option (bitumen, cement). | Permitted, but with strict limits (e.g., typically < 10% by weight) to maintain vapour permeability. | NZS 4298:2020 |