Environmental and structural analysis of cement-based vs. natural material-based grouting mortars. Results from the assessment of strengthening works

This paper focuses on the environmental and structural implications of grouting by means of mortar, one of the most commonly used techniques in the repair, strengthening and retrofitting works of damaged masonry buildings. Masonry structures represent a significant percentage of the building stock, and to guarantee their structural safety, minimizing the environmental impact of the repair works, is a main concern. However, few researches analyse the environmental consequences of those works and repair materials. Besides, the selection of the most adequate repair grouting, is a difficult task and an open research field. From the analysis of a representative strengthening work (the grouting of XVIth century columns in the Divino Salvador church, Cortegana, Spain), this study analyses the environmental and structural performance of different grouting mortars, extrapolating the results to different and more general scenarios. The analysed building materials are cement-based, natural hydraulic lime-based with or without artificial pozzolans and hydrated lime-based grouts with natural pozzolan and w/wo cement. After performing structural analyses, Incompatibility Risk assessment and Life Cycle Assessment (Embodied Energy and Global Warming Potential) on the strengthening works, normalization and weight factors have been applied to the results. Those factors make possible to compare substrate/grouting mortar compatibility, safety structural requirements and environmental impact. The results show that the best global behaviour, both structurally and environmentally, is provided by those grouts which contain higher quantities of pozzolans in the mix. The manufacturing phase is the less environmental-friendly stage. Results from this research could be applied to use more eco-efficient strengthening materials.