Analysis of mortars with old plastering waste using state-of-the-art method: nuclear magnetic resonance

Abstract One of the major problems we face today is the correct management of waste generated in all spheres of activity. Thus, the concept of sustainable development aims to develop strategies that prevent and solve problems already generated. Domain construction is the one that generates the most waste worldwide, according to recent studies, which requires the imposition of clear, effective, and future-proof measures to improve the environment and the health of the population. This paper is the continuation of a research program in which 3 types of mortar recipes are analyzed. The study involves replacement of aggregates, in different percentages (10% and 15%), with plaster waste from historic buildings. The obtained results show that the values fall within the limits stipulated in the norms in force, so the study will continue with the analysis of the samples using the state-of-the-art method: nuclear magnetic resonance. The paper aims to analyze the properties of the proposed mortars at the nanoscopic level, following the relationship between the plaster mortar matrix and the plaster waste introduced in different percentages in the samples. In addition, the impact of these wastes on the hydration of the cement and on the porosity of the composition of these mortars is also observed, being noticed that the relationship between the porosity of the samples and the mechanical resistances is inversely proportional, that is, the resistances decrease as the porosity increases. It will also be identified the location of hydrogen in the structure: in hydrated mineralogical compounds of cement and in large, medium and small pores. For each studied sample, the investigations were conducted at the age of 7, 14 and 28 days (even at 3 days for samples with 10% and 15% substitution of aggregates with old plastering mortars). The results for the proposed samples will be compared to the standard recipe.