Rice water for the consolidation of lime mortar

Already hundreds of years ago rice water was used in China to mix mortar – which contributes to an enormous durability. The reason for this is the polysaccharide amylopectin.

Rice plantations laid out in terraces.
The durability of lime mortar is increased by the addition of rice water. Image source: Sasin Tipchai / Pixabay (Symbol image). -

For almost 1500 years, many ancient Chinese mortars have remained unaltered despite exposure to atmospheric agents. The main reason for this long-term durability is the addition of sticky rice water to the standard mortar ingredients (lime and sand) following traditional recipes.

In recent years, these mortars have been methodically studied leading to the conclusion that amylopectin, a polysaccharide in the sticky rice, plays a crucial role in regulating calcite crystals growth, creating a denser microstructure and providing the mortar with hydrophobic properties which contributed to their survival.

Consolidation of calcareous substrates

In recent decades, nanolime products based on Ca(OH)2 nanoparticles suspended in alcohol or hydro-alcoholic medium have been extensively used for the consolidation of calcareous substrates mainly due to their chemical affinity and absence of side effects. Nanolime products have resulted in successful superficial consolidations. However, in-depth consolidation still needs to be achieved, and research needs to focus on ways to attain this objective.

A new study focused on the effect sticky rice had when used as a pre-treatment before applying nanolime for consolidation of lime mortars. Results showed that the use of sticky rice in combination with nanolime yields a higher degree of consolidation increasing drilling resistance and delivering hydrophobic properties although prolonged exposure to high temperature and moisture can compromise treatment durability.

The study has been published in Journal of Materials Science. July 2019, Volume 54, Issue 14.

Image source: Pixabay.

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