# The influence of lime type on the properties of traditional lime-soil materials

## TL;DR

This study compares different types of lime in soil materials for repairing historic buildings, finding that powdered lime is more reliable while blocky lime needs careful use.

## Contribution

The study provides a systematic evaluation of blocky quicklime's performance in lime-soil materials, revealing its dosage-dependent behavior and unique hydration mechanisms.

## Key findings

- Hydrated lime showed inferior strength and durability compared to quicklime types.
- Blocky quicklime performed best at 15% content but declined beyond due to expansion stresses.
- Powdered quicklime provided consistent, dosage-dependent performance suitable for high-performance needs.

## Abstract

The conservation of historic earthen structures requires repair materials that are both high-performance and historically appropriate. While archaeological evidence indicates that the historical use of blocky quicklime to make lime-soil materials, modern research and conservation practice often focus on its powdered counterpart, creating a knowledge gap. Thus, this work systematically evaluated the physical properties, microstructure, and composition of lime-soil materials prepared with blocky quicklime, powdered quicklime, and hydrated lime (at 10–20% content). The results demonstrated that hydrated lime yielded inferior strength and durability. Although both types of quicklime enhanced performance, they functioned through distinct mechanisms. Powdered quicklime provided consistent, dosage-dependent improvement, making it reliable for high-performance requirements. In contrast, blocky quicklime exhibited a pronounced optimum at 15% content; beyond this, performance declined due to expansion stresses from excess, partially hydrated cores, as identified by FT-IR spectroscopy. This study concluded that the choice of lime form was critical: powdered quicklime was recommended for predictable, broad-spectrum enhancement, whereas blocky quicklime could be effective but required strict dosage control to harness its unique potential and avoid damage. These findings provided a scientific basis for selecting and applying lime materials in the repair of earthen architectural heritage.