Evaluation of fresh-state application performance of a coating mortar based on aerial lime and tuffeau powder from stone sawing waste

Abstract

To reduce the overexploitation of granular resources, minimize the environmental impact of fine mortars, and limit the heritage impact during the rehabilitation of old tuffeau stone buildings in the Loire Valley, France, a new coating mortar has been developed. Composed of aerial lime and tuffeau powder from sawn stone blocks, this mortar promotes the reuse of mineral waste. Due to its use as a finish coat on external insulation vertically, it requires specific characteristics in its fresh state to facilitate its application and accurately replicate the original stone's aesthetic appearance in the restored buildings. Different additives were used to optimize the material's performance: superplasticizer (SP), shrinkage-reducing agent (SRA), air-entraining agent (AEA), and rheology modifier (RM). This paper examines the fresh state behavior of the developed material by employing a methodology that combines flow table and fall cone tests. It provides an objective approach capable of assessing consistency and determining application requirements that align with the empirical properties recommended by professionals in the field. Additionally, the entrained air content and bulk density were determined. The flow table failed to identify the impact of adding AEA on application performance. However, the fall cone test revealed its influence, highlighting AEA’s role in facilitating mortar application. The SP predominantly reduced the water requirement needed to achieve specific flowability. Integrating RM with AEA enhanced the mortar’s ability to retain entrained air.