The Influence of Dry Hydrated Limes on the Fresh and Hardened Properties of Architectural Injection Grout.

Andreja Padovnik,Violeta Bokan-Bosiljkov

doi:10.3390/ma14195585

Andreja Padovnik, Violeta Bokan-Bosiljkov

Open Access

https://doi.org/10.3390/ma14195585

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Abstract

Dry hydrated lime is an air binder often used in architectural injection grouts. This study compared the influences of three commercially available dry hydrated limes on the injection grouts’ workability and mechanical properties. The main differences between the limes were in their chemical and mineralogical composition and Blaine specific surface area. The grouts were composed of dry hydrated lime, finely ground limestone filler, water, and super plasticiser. Subsequent results obtained revealed that the Blaine specific surface area is not directly related to the fresh grout properties. Grain size distribution and shape of lime particles and their aggregates in the water suspension are key parameters influencing the following fresh grout properties: fluidity, injectability, the mixture’s stability, and water retention capacity. However, the lime injection grouts’ mechanical strengths were higher in relation to an increase in the content of portlandite and the Blaine specific surface area of the dry hydrate.

Highlights

Hydrated lime was one of the prevailing binders for renders, plasters and masonry mortars up to the 20th century, when cement-based materials took the dominant role in the building sector
This study addresses the influence of three dry hydrated limes on architectural injection grouts’ fresh and hardened properties
The main differences between the hydrated limes could be found in their chemical and mineralogical compositions, particle density, and specific surface area values, which indicate that the industrial production and limestone composition were not the same for the studied limes

Summary

Introduction

Hydrated lime was one of the prevailing binders for renders (external wall mortar layers), plasters (internal wall mortar layers) and masonry mortars up to the 20th century, when cement-based materials took the dominant role in the building sector. Cement-based materials were applied to repair historic buildings where hydrated lime composites were used to bond the masonry units and protect masonry walls. Due to incompatibility with the historic masonry fabrics and additional unfavourable characteristics of the Portland cement binder—such as salt formation—the historic masonry buildings suffered new extensive damage. The hydrated lime binder that provides similar composition and properties as the original historical architectural fabrics has become widely used to repair and restore historic lime plasters and renders. Where consolidation or re-attachment of such architectural surfaces is needed, architectural injection grouts prepared using the hydrated lime binder are often used to ensure compatibility between the new and historical materials and components [1]. A comprehensive state of the art regarding the composition of architectural injection grouts used in restoration practise between 1950 and 2015 is given in [2]

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