Efeitos físico-químicos e microestruturais de particulados na reologia e propriedades mecânicas de compósitos cimentícios

Abstract

The execution of rendering lime mortars services in public works, frequently subject to forensic analysis by the Federal Police, represents a significant cost in the context of the contracts examined. Given the recurrent scenario of fraud and irregularities in the execution of these services, there is a clear need for more robust and scientifically grounded methodologies to support forensic activities. In this context, this study aims to evaluate the main structural and microstructural parameters of rendering mortars and their correlation with the quantification of aggregates and binders present in the applied mixtures. This evaluation is carried out using advanced laboratory macro and microcharacterization tests, including techniques such as Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Multi-analysis Zonning Expert (MAZE) analysis, and X-Ray Diffraction (XRD). By defining characteristic parameters for a representative universe of rendering lime mortars with a volume ratio of 1:2:8 (cement:lime:sand), with special attention to the variation in aggregate granulometry, it was possible to establish criteria for identifying these materials. During the formation of this representative universe, detailed analyses of the packing of the aggregates used were conducted, as well as the influence of different particle size distribution curves on the behavior of the mortars. It was highlighted that the correct choice of aggregate can lead to lower cement consumption in the composite, generating both financial and ecological gains. It was also assessed that the legal cost reference for budgeting mortars in public works, SINAPI, effectively fulfills its role. The study proposes a methodology based on physicochemical parameters that assists in the analysis of overbilling due to poor quality execution of lime mortars, through the reconstitution of their mix design.