The lime mortar is made by
Try it first: pick an option, then read the explanation.
Understanding Lime Mortar
Lime mortar is a traditional building material used to bond masonry units like bricks, stones, and blocks. It is made by mixing a binder (lime), a fine aggregate (sand), and water. The choice of lime is critical, as the mortar needs to develop sufficient strength and durability for the structure. For mortar, especially in structural applications, the ability to set and harden is paramount.
Detailed Analysis of the Options
C. Hydraulic lime
This is the correct answer. Hydraulic lime is the preferred choice for making lime mortar for masonry and structural work. Because it contains clay impurities, it has inherent hydraulic properties, meaning it can set and harden by reacting with water, similar to cement. This gives the mortar the necessary strength and durability, and allows it to be used in damp conditions or thick walls where air circulation is limited.
B. Fat lime / D. White lime
These are incorrect for making structural mortar. Fat lime (also called white lime or pure lime) has high plasticity and is excellent for plastering and whitewashing, but it lacks the inherent setting compounds of hydraulic lime. It hardens very slowly by absorbing CO₂ from the air and does not achieve the same strength, making it unsuitable for most masonry mortar applications.
A. Quick lime
This is incorrect. Quicklime is the raw, unslaked form of lime (CaO). It cannot be used directly to make mortar. It must first be slaked with water to produce hydrated lime before it can be mixed with sand.
Summary: Lime Types for Different Applications
| Lime Type | Key Property | Best Application |
|---|---|---|
| Hydraulic Lime | Strength, Hydraulic Set | Mortar, Foundations, Damp areas |
| Fat Lime (Pure/White) | Plasticity, Whiteness | Plastering, Whitewashing |
Study Tips
- Mortar needs Muscle: Think of mortar as the "muscle" holding the bricks together. It needs strength. Hydraulic lime provides that strength.
- Fat Lime is for Finishing: Fat lime is like the "skin" or "paint." It provides a smooth, white finish but isn't meant for heavy lifting.
- Hydraulic = Mortar: This is a key association to remember for exams. When you see "lime mortar," think "hydraulic lime."