Influence of substrate pore structure and nanolime particle size on the effectiveness of nanolime treatments

Nanolime is a promising consolidation treatment for the conservation of historic structures thanks to its high compatibility with carbonate-based substrates. Nanolime products can effectively reduce the porosity and restore the mechanical properties of treated surfaces. Whilst the popularity of nanolime has been growing, its consolidation mechanism still needs to be fully understood when applied to porous substrates. The aim of this paper is to determine the influence of nanolime particle size and substrate pore structure on the effectiveness of nanolime treatments. Results suggest that nanolime products with larger particle size tend to close predominantly large sized pores, while nanolime with smaller particle size tends to fill both large and small pores equally. These results suggest that for a consolidation treatment, the nanolime product must be chosen taking into consideration the substrate pore structure

Behavior to Salt Crystallization of Repointing by Ready-Mix Mortars: Experimental Data and Application of a Probabilistic Model

reserved3Luigia Binda; Elsa Garavaglia; Cristina TedeschiBinda, Luigia; Garavaglia, Elsa; Tedeschi, Cristin

Thermo-poro-mechanics Modelling of Gypsum Dehydration

Understanding the behaviour of natural calcium sulphates is important to ensure the sustainable integrity of civil structures. The phase transitions of these minerals are associated with considerable volume variations, creation of porosity with local defects, and water exchanges. Such changes can jeopardise the integrity of structures when the conditions that trigger the phase transitions are encountered. This paper uses advanced poromechanics to investigate the dehydration of gypsum when subjected to heating. The proposed approach includes the fundamental principles of non-equilibrium thermodynamics as well as the coupled multi-physics of thermal, hydraulic, mechanical and chemical (THMC) processes. A novel mathematical formulation is introduced to describe the coupled constitutive relationships in the reversible and dissipative regimes as well as the consequent partial differential equations that describe the THMC processes. The governing equations are integrated numerically using the finite element method. The obtained results show a significant correlation between gypsum dehydration and creation of fluid pathways. The proposed model can be generalised to describe the effects of dehydration in other minerals carrying water in their crystal structures.</p